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Ecological paradigms, species interactions, and primary succession on phosphate-mined land

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Ecological paradigms, species interactions, and primary succession on phosphate-mined land
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Dunn, William James, 1954-
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Ecological succession ( jstor )
Ecosystems ( jstor )
Germination ( jstor )
Marshes ( jstor )
Paradigms ( jstor )
Seedlings ( jstor )
Soil science ( jstor )
Species ( jstor )
Vegetation ( jstor )
Wetlands ( jstor )
Dissertations, Academic -- Environmental Engineering Sciences -- UF
Ecological succession ( fast )
Environmental Engineering Sciences thesis Ph. D
Phosphate mines and mining -- Environmental aspects ( fast )
Plant succession ( fast )
Reclamation of land ( fast )
Revegetation ( fast )
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bibliography ( marcgt )
theses ( marcgt )
non-fiction ( marcgt )

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Thesis:
Thesis (Ph. D.)--University of Florida, 1989.
Bibliography:
Includes bibliographical references (leaves 182-192).
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Typescript.
General Note:
Vita.
Statement of Responsibility:
William James Dunn.

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ECOLOGICAL PARADIGMS, SPECIES INTERACTIONS, AND
PRIMARY SUCCESSION ON PHOSPHATE-MINED LAND












by

WILLIAM JAMES DUNN




















A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMEMT
OF THE REQUIREMENTS FOR THE DEGREE OF
DOCTOR OF PHILOSOPHY

UNIVERSITY OF FLORIDA 1989














ACKNOWLEDGMENTS


I thank my faculty committee members Dr. G. Ronnie Best, Dr. H. T. Odum, Dr. Clay Montague, Dr. Steve Humphrey, and Dr. Warren Viessman for their guidance.

The research was supported by Florida Institute of Phosphate Research grant number 81-03-008, "Enhanced Ecological Succession Following Phosphate Mining," G. R. Best and H. T. Odum, principal investigators.

Several mining companies provided support and information. Marsh studies at Fort Green were in part supported by Agrico Mining Company. Mobil Chemical Company, International Minerals and Chemical Company, Gardinier Phosphate Company, and W. R. Grace and Company provided access to study sites.

Special thanks go to those who assisted with field work, Pete Wallace, Mel Rector, Alfonso Hernandez, Juan Hernandez, Bob Tighe, Jim Feiertag, and Tim King. The late Bill Coggins ran all the SAS analyses. Dr. Ron Myers allowed the use of unpublished data on seed banks at Lake Kanapaha.

Marla Mittan helped with technical editing. I wish to thank CH2M HILL for making its resources available during the final phases of this dissertation.




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I sincerely thank my wife, Buffy, for her eternal patience and support during this degree. Finally, I thank my two sons Charlie and Sam for making life bearable during the "crunch."














































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TABLE OF CONTENTS


ACKNOWLEDGMENTS ...........................................ii

ABSTRACT.....................................................vi

INTRODUCTION...............................................1

Previous Studies of Succession on Mined Land.............2
Background and Concepts................................... 3
Succession Theory...................................... 3
Wetland Succession.....................................9
Role of Consumers .................. ............13
Competing Paradigms of Succession .......................20
Initial Floristics....................................20
Inhibition ............................................20
Relay Floristics........................................24
Coevolution.............................................24
Self-organization .....................................24
Changes in Paradigms.................................... 24
Hypotheses and Objectives.................................27
Marsh Development..................................... 28
Upland Forest Development .............................29
Mound-building Ants and Ecosystem Development.........30
Description of Study Sites.............................. 33


METHODS ...................................................43

Marsh Development.......................................43
Seed Bank Survey.......................................43
Marsh Transect Study..................................45
Upland Forest Studies...................................47
Direct-seeded Plots...................................50
Seedling Transplant Plots............................51
Mound-building Ants and Upland Succession...............53
Survey of Mound Density............................... 53
Physical Soil Analyses................................53
Chemical Soil Analyses ................................ 55
Plant Growth Study ....................................57
Statistical Analysis...................................58





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RESULTS ...................................................59

Marsh Development.......................................59
Seed Bank Survey................................... . 59
Marsh Transect Study ..................................72
Upland Forest Succession Plots...........................90
Seed Germination and Survival .........................90
Height Growth in Seed Plots...........................105
Height Growth in Transplant Plots ....................112
Mound-building Ants..................................... 114
Mound Survey..........................................114
Plant Growth Study....................................114
Chemical Soil Analyses.................................116
Physical Soil Analyses............................... 120

DISCUSSION ...............................................124

Marsh Development......................................124
Seed Bank Formation................................. 124
Formation and Stability of Macrophyte Communities....126
Wetland Succession Model ............................. 132
Role of Life History Characteristics................. 132
Importance of Allogenic and Autogenic Factors ........ 132 Eclectic Wetland Succession Paradigm.................135
Upland Forest Succession Plots..........................139
Seed Germination and Survival.......................139
Height Growth........................................ 146
Species Removal...................................... 150
Competition........................................... 153
Succession ...........................................155
Caveats .....................................................157
Mound-Building Ants......................................158
Mound Survey...........................................158
Ant Mound Roles.......................................159
Ant Model..............................................166
Eclectic Synthesis of Paradigms and Implications for
Reclamation Design......................................168
Inhibition.............................................170
Initial Floristics...................................172
Relay Floristics .....................................174
Coevolution..........................................174
Self-organization ....................................176

CONCLUSIONS.............................. ...............179

REFERENCES............................ .................. 182

BIOGRAPHICAL SKETCH......................................193





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Abstract of Dissertation Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy



ECOLOGICAL PARADIGMS, SPECIES INTERACTIONS, AND
PRIMARY SUCCESSION ON PHOSPHATE-MINED LANDS By

WILLIAM JAMES DUNN

May 1989


Chairman: Dr. G. Ronnie Best Major Department: Environmental Engineering Sciences


Field studies on phosphate-mined lands were undertaken to evaluate several paradigms for explaining succession, including inhibition, initial floristics, relay floristics, coevolution, and self-organization. Primary objects of study were wetland seed bank formation, formation and stability of wetland macrophyte communities, interactions between colonizing species and trees on upland sites, and the role of mound-building ants in upland succession.

A survey of natural and post-mining wetlands showed seed banks develop rapidly, but contain only wind-dispersed early successional species. Late successional marsh species can be added as an instant seed bank through muck material from a donor or, in some cases, by planting.


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The development of a reclaimed marsh was monitored over its first four growing seasons. Results showed that while very different plant communities developed with the application of muck from a donor marsh as compared to natural succession, both types of initially established macrophyte communities remained stable throughout the monitored period.

Upland succession was enhanced with direct seeding and seedling transplants in four treatments: natural colonization, enhancement of natural colonizers, enhancement with legumes, and weeding. Tree seedlings had better height growth in plots in which the colonizing weeds were removed. Tests indicated that the five paradigms investigated operated concurrently during primary succession.

Fire ants (Solenopsis invicta) were the most commonly observed invertebrate species on mined lands, with well established populations within the first year after mining. Mound densities on 1- to 5-year old sites ranged from 560 to 2,000 per hectare. Mound soils had higher concentrations of sodium, potassium, total nitrogen, and organic matter than the adjacent non-mound soils. In greenhouse experiments, a grass and a woody plant exhibited enhanced growth on mound soils. Water infiltration rates were 5 to 100 times greater on mound soils than non-mound soils.

The view of the competing paradigms as mutually exclusive was not supported. A unifying paradigm may be possible from a more eclectic synthesis of the inhibition, initial


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floristics, relay floristics, coevolution, and selforganization models.
















































viii














INTRODUCTION


The pattern and process of ecosystem development, usually called succession, are a main focus of the science of ecology. The paradigms used to understand succession are still in controversy, and the pattern and process of ecosystem development are still much debated. A clear understanding of succession provides an opportunity for forming rational and cost-effective land reclamation techniques and policies that will enhance the successional process on disturbed lands. It is not possible to predict the long-term development of created and restored ecosystems without a clear understanding of the natural processes of ecosystem development. Unfortunately, the ecological literature remains divided on the fundamentals of succession, especially the interactions between early colonizing plant species and late successional species and the role of non-trophic interactions between producers and consumers.

The establishment of vegetation is one of the first stages of primary succession on an abiotic substrate, whether the succession results from geologic uplift, glacial retreat, volcanic lava flow, landslide, or strip-mining. The postmining landscape is a relatively simple ecosystem of few








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species but provides a rich environment for testing paradigms describing the pattern and process of succession. Detailed ecological studies of the recovery process on mined lands may also identify some solutions to existing reclamation problems. The succession and human-managed reclamation of phosphatemined lands in central Florida provides and opportunity to evaluate successional theory and use the knowledge to facilitate reclamation. This dissertation examines successional processes on phosphate-mined lands, especially marsh development, upland forest development, and the roles played by seed banks and mound-building ants.

In a few cases an understanding of wetland succession has been translated into a successful technique for wetland creation and restoration. In the Tampa Bay area it was observed that formerly unvegetated intertidal areas were quickly colonized and stabilized by smooth cordgrass (Spartina alterniflora) which presumeably helped mangrove seedlings to become established years later (Lewis 1982). In 15 to 20 years the mangroves eventually shaded out the cordgrass and became dominant. Lewis developed a technique for establishing a nurse crop of cordgrass which has since become a common practice for mangrove establishment.


Previous Studies of Succession on Mined Lands


Many studies of unreclaimed mined lands have documented the paucity of late successional species on upland sites








3

(Humphrey et al., 1978; Schnoes and Humphrey, 1987; Wallace, 1988) and wetland sites (Clewell, 1981; Rushton, 1983, 1988). Vegetation studies of phosphate clay settling ponds reported an initial cover of cattails (Tvyha sp.) and water hyacinths (Eichhornia crassipes) followed by primrose-willow (LudwiQia peruviana) and willow (Salix caroliniana). Wax-myrtle (Myrica cerifera) and vines dominated sites as they continued to dry (Zellars-Williams and Conservation Consultants, 1980; King et al. 1980; Rushton, 1983). These studies generally describe an arrested succession in which the initial species composition of primary invading species is perpetuated. In contrast, other studies (Kangas 1979, 1983) have described older sites where succession did not appear to be arrested or inhibited. In cases with a nearby seed source, sites were invaded by hardwood species such as red maple (Acer rubrum), laurel oak (Quercus laurifolia), and live oak (Quercus virginiana) (Zellars-Williams and Conservation Consultants, 1980; Rushton, 1983).


Background and Concepts

Succession Theory


Clements (1916) described succession as a universal, orderly process of progressive change. He asserted that the community developed from diverse pioneer stages to converge on a single, stable, mesophytic community (monoclimax) under








4

the control of the regional climate. He held that in succession, the community repeated a sequence of stages, similar to the development of an individual organism from birth through death, that was an orderly directional process predictable in its development. As succession proceeded, the community increasingly controlled its own environment and, barring disturbance, became a self-perpetuating climax. Succession occurred as waves of plant populations made conditions suitable, or "prepared the way," for the next wave and often to the detriment of their own continued survival.

To other ecologists of the time, the plant community was less well defined and succession less orderly, directional, and predictable than Clements suggested. Alternative concepts of succession voiced by Gleason (1917, 1926, 1939) advocated an individualistic, population-based approach in which the plant association is seen as a coincidence rather than an interdependent entity. The distribution of a particular species in the landscape depends on its migration characteristics and environmental requirements, and the plant community is an artifact solely dependent on the grouping of species with overlapping environmental requirements. Given sufficient time, all species had equal access to all sites, but species were found only on those sites with the appropriate environmental conditions. According to this allogenic theory, a particular species grows in the company of any other species with similar requirements and eventually








5

disappears from areas where environmental conditions are no longer favorable.

Egler (1954) also found fault with Clements' view of succession, but stressed the role of autogenic processes in old-field community succession. He applied the name "relay floristics" to Clements' sequential appearance and disappearance of groups of species and posed an alternative mechanism he termed "initial floristics" in which old-field plant community development after abandonment unfolds from an initial flora already residing within the soil, without additional increments by further invasion. As each successive species or group subside, another that has been present from the beginning, assumes dominance. In a forest succession sequence, eventually only the trees are left. Egler noted that the actual development of vegetation in an old-field is a function of both autogenic processes but that in secondary succession, initial floristics determined the composition of the resulting community and relay floristics played a relatively minor role. He also noted that allogenic factors were important determinants of community composition.

The Clementsian and Gleasonian views of succession define opposite poles within the field of ecology. In the modern analogs, the arguments have been refined but many of the key issues and differences have remained intact. The Clementsian tradition has a modern synthesis in systems ecology, while the modern proponents of the Gleasonian view are typically aligned








6
with the discipline of population ecology. Dichotomies still center on questions of holism versus reductionism, the evolutionary unity of communities, and whether ecosystems possess emergent properties.

E.P. Odum (1969) provided a modern ecosystem reformulation of Clementsian succession. Odum noted the similarity of succession to the development of individual organisms and converged with Clements' description of succession as an orderly process that is reasonably directional and therefore predictable, resulting from modification of the physical environment by the community (autogenic) and culminating in a stabilized (climax, mature) ecosystem with homeostatic properties.

Confusion developed when some ecologists described the ecosystem as having an evolutionary unity. Patten (1975) called the ecosystem a "coevolutionary unit." Webster et al. (1974) stated that a basic assumption of ecosystem analysis is that ecosystems are units of selection and evolve from systems of lower selective value to ones of higher selective value that optimize utilization of essential resources. Other ecologists did not view communities or ecosystems as evolutionary units because inheritance of genes is passed separately by the many species.

H.T. Odum (1983) describes succession as a selforganizing process by which ecosystems develop structure and processes from the available choices supplied by seeding. The








7

organization develops new programs for succession with which species prevail that are reinforced by controls and material cycles of the next larger system. This view has maximum power as a self-design principle, in that there is survival of those combinations of components that contribute most to the collective power of the system. Species combinations are reinforced that divide up and optimize the use of resources to collectively maximize productivity, and species substitutions occur through time as new choices are offered and selected. Some Darwinian selfish selection is involved but is regarded as secondary. Emphasis is on selection of relationships that make the system perform, with evolution ultimately occurring but on a longer time interval.

Modern proponents of the Gleasonian individualistic view (McCormick, 1968; Drury and Nisbet, 1971, 1973; Horn 1971, 1974, 1975; Pickett, 1976; Connell and Slatyer, 1977) find the classical Clementsian paradigm and its modern incarnation, the holistic-ecosystem representation, unpalatable. McIntosh (1982) points out that the studies by these researchers share at least three characteristics:

1. They are commonly cited in recent discussion of
succession as providing "new" insights for successional
theory.

2. They are explicitly critical of Clements' holistic,
organism theory of succession and of what they interpret as the successional theory ofthe organismic, holistic,
ecosystem ecology expressed by ecosystem ecologists.

3. The alternative models of succession proposed advocate
an individualistic, population-based approach emphasizing life history attributes of organisms and the consequence








8

of natural selection as the essential basis of a modern
theory of succession.

Connell and Slatyer (1977) described three models by which species may replace each other in a successional sequence. They assumed no further changes in the abiotic environment and that certain species usually appear first because they have the ability to produce large numbers of easily dispersed seeds, which are not adapted to germinating and growing on occupied sites.

Model 1 assumes only certain early successional species are able to colonize a site immediately after disturbance, as in the "relay floristics" model of Egler and the classical Clementsian view.

Models 2 and 3 assume that any arriving species may be able to colonize, even those that typically appear late in the sequence. These are alternative forms of Egler's "initial floristics" model. In model 2, early colonists neither increase nor reduce the rates of recruitment and growth of later successional species. Species that "appear" later in the successional sequence are those that arrived either initially or later but grew very slowly. In Connell and Slatyer's model of initial floristics, the sequence of species is determined solely by life history characteristics. In contrast, model 3 (termed inhibition) holds that once early colonists secure the available space and resources, they inhibit invasion by subsequent species and suppress the growth








9

of those already present. Invasion is only possible when the dominating species are damaged or killed, thus releasing resources. In model 3, the tolerance of late successional species is important, as it allows them to survive long periods of suppression.


Wetland Succession


Much of the debate on succession focuses on the factors controlling the course of community development. Controlling factors are typically grouped as autogenic, those generated by the biological community itself, or allogenic, coming from outside the biological community.

In some views of succession (Clements, 1916, 1920) wetlands were considered a transient stage between aquatic communities and a terrestrial forest climax. In this concept, aquatic areas may gradually fill from sediment deposition and organic peat formation. Emergent macrophytes, shrubs, and trees gradually appear, and the community continues to transform the wetland site into a terrestrial one. Where sediment accumulation raises the ground elevation above water levels, a change to drier vegetation is observed.

In wetlands where inorganic sediments are not being added and land is not being elevated, peat formation may not proceed beyond water levels (Odum, 1984). In warm climates, organic matter oxidizes or burns in dry weather, arresting succession. Many wetland ecosystems in this sense are a form of climax.








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A major influence of Clements' ideas on wetland ecology was the tendency to interpret zonation patterns in wetlands as indicators of future successional trends. Succession in wetlands was viewed as a directional, autogenically-driven process leading inevitably to some terrestrial climax. Evidence leads to the conclusion that both allogenic and autogenic processes act to change wetland vegetation and that the Clementsian idea of a regional terrestrial climax for wetlands is often inappropriate.

Van der Valk (1981) claims that Pearsall (1920) was one of the first to apply Clements' concept of succession to wetlands. The concept of the monoclimax was eventually replaced by Whittaker's concept of pattern climax (Whittaker, 1953), which was based on gradient analysis studies that documented the independent distribution of species along environmental gradients. The effect was to de-emphasize the successional interpretation of seres, or vegetative zones in the case of wetlands, and to focus on the correlation of plant species with specific types of environmental conditions.

Van der Valk (1981) proposed a "new" definition of wetland succession, based on the ideas of H.A. Gleason (1917, 1926, 1939), that did not presuppose the existence of a climax vegetation. Van der Valk defined succession as a change in the floristic composition of the vegetation of an area from one year to another which, is narrower than Gleason's definition of it as any change, quantitative or qualitative,








11

in the vegetative cover of an area. In the van der Valk model, succession occurs whenever a new species becomes established or an existing one is extirpated.

The model is based on the life history characteristics of the wetland species and the interaction of the species with the prevailing environmental conditions (see Figure 1). Van der Valk classified wetland plant species into 12 life history strategies based on potential life span, propagule longevity, and propagule establishment requirements. Under this scheme, each life history type has its own unique set of characteristics and associated responses to prevailing environmental conditions, which act as a "sieve" in determining the species composition of the wetland. As environmental conditions change, so does the action of the sieve and, therefore, the species present.

The van der Valk model focuses on the wetland seed bank as the key biological component. The functional significance of seed banks lies in providing the plant community with an in situ means of regenerating from naturally occurring disturbances (Grime, 1978). Van der Valk (1981) and van der Valk and Davis (1976, 1978) have aptly documented and demonstrated the role seed banks play in the vegetation dynamics of prairie glacial marshes that undergo cyclic patterns of flooding-drawdown-drought. In prairie glacial marshes and other marsh systems (Keddy and Reznicek, 1982;


























Figure 1. General model of Gleasonian wetland succession proposed by Van der Valk (Source: after Van der Valk 1981)










Environmental Sieve (State: Drawdown)


AD-I -
AD-II .--- - AD-II
PD-I----, . IAS-II
WETLAND ASPD-II ,.--- -- PD-II
VD-I F" VEGETATION " . PS-II VD-IP----+*1
VO- 1l
SPotentially
: Extirpated
.. .. .. .. . s .. . .. .. .. .. . .. .. ** *** Soecies


AS- AS- PS- PS- VS- VSI II II II Ii


KEY
A-Annual
P-Perennial with Limited Life Span V-Vegetatively Progated Perennial
D-Dispersal Dependent Species - Short-Lived Seeds
S-Seed Bank Species - Long-Lived Seeds
I -Species Established Only in Absence
of Standing Water
II-Species That Can Be Established In Standing
Water








14

Leck and Graveline, 1979), seeds remain dormant, yet viable, in the seed bank during periods in which environmental conditions are unfavorable for germination, growth, and development of the population. In wetland and upland communities, seed banks provide a mechanism for rapid recovery from catastrophic mortality resulting from fire (Johnson, 1975), clear-cutting (Marks, 1974), and drought (Myers, 1983). Marks (1974) has shown that the rapid response of pin cherry to clear-cutting in the Hubbard Brook ecosystem helped minimize the effect of canopy removal on nutrient losses from the ecosystem. Egler's initial floristic hypothesis portrays old-field succession as a seed bank response.

The van der Valk wetland model can be reformulated using energy circuit language (Figure 2). Van der Valk's 12 life history categories are simplified to mudflat annuals, emergent macrophytes, and aquatic macrophytes. The actual composition of the wetland is determined by the interaction between the existing plant community, the propagules present, and environmental conditions. Logic switches are used to indicate the actions of the "environmental sieve."


Role of Consumers

Various roles are attributed to consumers in ecosystems beyond simple trophic relationships of herbivory and predation. These non-trophic interactions typically involve

















Conditions





Environmental
"Siewe II Annual









Sun Seed
Flat
Annuals


Emergent







& -( Aquatic Seed *A1.Seed




Aquatics Bank AU- Seed




















Figure 2. An energy circuit diagram of a Gleasonian model of wetland succession (redrawn from Van der Valk 1981).








16

hypothesized feedback loops between species, termed indirect effects. Non-trophic interactions are concerned with ecosystem structure and function, which, according to the individual selection theories of traditional population ecology, are not subject to adaptive evolution.

It has been suggested that heterotrophs regulate autotrophs and thereby control the rate of energy production ( O'Neil et al., 1975; Lee and Inman, 1975). Owen and Weigert (1976) asked the question, whether consumers maximize plant fitness, and developed a hypothesis that consumers, like pollinators, have a mutualistic relationship with plants. They suggested that plants may exploit consumers to increase fitness. If, through the action of consumers, a nutrient that is in short supply is made more available to the plant, the relatively small amount of photosynthate lost may be more than compensated.

Mutualistic interactions may involve a direct trophic link, such as those just described, but other non-trophic interactions between species very much affect fitness but do not involve competition or predation. For example, intensive fiddler crab (Uca pugnax) activity in the tall-form of saltmarsh cordgrass (Spartina alterniflora) stands improves soil drainage, oxygenates marsh sediments, and increases belowground decomposition of plant-generated debris (Bertness, 1985), all of which can affect the growth rate of the cordgrass.








17

Population ecologists view non-trophic interactions as byproducts of the evolutionary process. Wilson (1980) described the problem as one in which traditional investigators within the discipline of population ecology assumed that the community structure was already in place. They then focused on relatively superficial forms of competition and predation, while ignoring the structure that actually determined the parameter values of the models.

Productivity in ecosystems depends on recycling and conservation of nutrient resources. The actions of consumers may cause a nutrient in short supply to become relatively more available. When primary production is nutrient-limited, heterotrophic activity, which accelerates mineralization, may help increase it. The importance of heterotrophs as regulators of ecosystem processes far outweighs their importance as measured by calories or grams of matter, but rather lies in how their characteristics affect or regulate ecosystem processes (Chew, 1974; Odum, 1982).

Numerous examples can be found of the regulatory role played by consumers. Vertebrate herbivores have been shown to increase productivity of grasslands (McNaughton, 1975). Platt (1975) showed the influence that badger mounds have on soil properties and the pattern and distribution of some plant species. Burrowing rodents can act as nutrient pumps, bringing materials to the surface from below (Abaturov, 1972). In forest soils, litter accumulated and decomposition slowed








18
when earthworms were removed (Witkamp, 1971). Earthworms stimulated the growth of potted barley seedlings, possibly by increases in vitamin B12 (Atlavinyte and Dacinlyte, 1969). Dung beetle activity was found to be almost as effective as mechanical mixing in enabling plants to benefit from the nutrient storages in dung (Bornemissza and Williams, 1970). Leaf cutter ants (genus Atta) reduced primary productivity by reducing leaf area, but more than made up for that loss by returning materials to the soil (Lugo et al., 1973).

Mound-building ants can produce localized concentrations of organic matter and nutrients, resulting in changes in densities of bacteria, fungi, and plants (Czerwinski et al., 1971). They can affect the physical and chemical aspects of soil as well as the distribution of plants, bacteria, and fungi, and are important in making channels and burrows. Hopp and Slater (1948) felt ants could be as effective as earthworms in creating conditions for improved plant growth, while Thorpe (1949) indicated that ants may produce greater effects than earthworms. Shrikhande and Pathak (1948) reported that ants increased the organic matter content of soils second only to earthworms.

Numerous studies have shown chemical differences between mound and nearby non-mound soils, with evidence of higher levels of exchangeable cations, micronutrients, nitrogen, phosphorus, and organic matter, as well as differences in pH and conductivity (Czerwinski et al., 1969, 1971; Gentry and








19

Stiritz, 1972; Rogers and Lavigne, 1974; Wali and Kannowski, 1975; King, 1977; Petal, 1978; Levan and Stone, 1983; Culver and Beattie, 1983). Enhanced nutrient levels in mound soils are attributed to microbially-mediated mineralization of organic waste products in the mound (Petal, 1978). This is supported by the work of Czerwinski et al. (1971), who showed the abundance of bacteria and fungi in ant mounds is higher than in the surrounding soil.

Mound-building ants profoundly alter the soil profile characteristics at their nest sites ( Baxter and Hole, 1967; Salem and Hole, 1968; Wiken et al., 1976; Wali and Kannowski, 1975; Alvarado et al., 1981; Levan and Stone, 1983). Mound soil has been shown to differ from nearby soil in bulk density, porosity, and infiltration capacity (Rogers and Lavigne, 1974; Rogers, 1972; Wali and Kannowski, 1975).

Through their influence on soils, ants can affect microtopographic heterogeneity, which can influence species composition, standing crop, and successional status of the local vegetation (Petal, 1978; Rogers, 1974; Gentry and Stiritz, 1974; King, 1977; Culver and Beattie, 1983). Herbs flourish on abandoned nest sites of harvester ants (Gentry and Stiritz, 1972) and are known to affect seed distribution. Ants are known to alter seed shadows in deserts (Bullock, 1974; O'Dowd and Hay, 1980), mesic environments (Beattie and Lyons, 1975; Handel, 1987; Beattie and Culver, 1981), and tropical forests (Roberts and Heithaus, 1986). Some plant








20

species known as myrmeccochores have a food body on their seed that is eaten by ants, which then disperse the seeds while returning food materials to the mound.


Competing Paradigms of Succession


The preceding discussions have revealed five competing paradigms of succession: two individualistic, life historybased models (initial floristics and inhibition) and three holistic ecosystem models (relay floristics, coevolution, and self-organization). An energy circuit language diagram of succession is shown in Figure 3a that includes early and late stage plants, seeding, and nutrient recycle. Additional controls and pathways are added to represent various paradigms for the interactions between early and late successional species (Figures 3b-3f). The concept of each paradigm is briefly summarized below.

Initial floristics. Early and late successional species coexist with the same resources (Figure 3b). The early species modify the site so that it is not suitable for their continued reproduction, but have no effect on the recruitment of late species.

Inhibition. Early and late successional species compete for available space and resources, such as light, nutrients, and moisture (Figure 3c). Rapidly dispersing, fast growing early species colonize available open space and capture available resources, inhibiting the establishment of later
























Figure 3. Energy systems diagram of succession: (a) with some of the main pathways of organization, seeding, and nutrient cycle; (b) control in "initial floristics"; (c) control with inhibition; (d) control with "relay floristics"; (e) control with coevolution, pathways permanent; and (f) controls from self-organization and reinforcement from animals and larger surrounding system.





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In I f I I/ I

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24

species. Slower growing late successional species can only become established when the early colonizers have been killed or disturbed.

Relay floristics. Late successional species are unable to become established on bare ground; they arrive and become established only after some critical level of development has been reached (Figure 3d). Late successional species gradually displace the early colonizing species. Competition for light results in poor growth and reproduction by early colonizing species, when later successional species are established.

Coevolution. An expanded version of the relay floristics model that also recognizes a long-term relationship between species (e.g., feedback relationships between and among trophic levels) (Figure 3e).

Self-organization. Producers, consumers, and decomposers are linked in a dynamic feedback network in which each trophic level is composed potentially of many species. Actual species composition of the community is a function of the system's self-organizing choices, which reinforce those combinations that optimize the use of resources and maximize productivity (Figure 3f). Controls and reinforcement are shown from animals and larger scale phenomena of the surrounding system.

Changes in Paradigms


The continuing contradictions about succession after many decades of study suggest that more may be involved than a








25

straightforward, objective, scientific consideration. Ecology and the succession concept may be in the midst of a revolution (McIntosh, 1983) and specifically a change in paradigms, which Kuhn (1970) has described as the way a scientific discipline progresses.

A common and idealized image of a scientific discipline is that it is universal, objective, and unbiased, with free communication and mutual comprehension among its members. Historians of science show this to be a simplistic and inaccurate view, and discuss the hypothesis of the "invisible college" as the basis of the organizational patterns associated with major advances and changes in paradigms within a scientific discipline (Crane, 1972; Griffin and Mullins, 1972). The invisible college hypothesis argues that any discipline, especially one in a state of change, is subdivided into loose networks of scientists with varying degrees of cohesiveness and continuity. According to Griffin and Mullins (1972) such networks conform to the following criteria:

1. Their members believe they are making major changes in
concept or methodology and the word revolution is much
in evidence.

2. Members do not consistently observe the attitude of
disinterested objectivity typically associated with scientists and may be passionate and one-sided advocates
of a "ruling theory."

3. There is commonly a close, even somewhat closed, informal
communication network within the network.

4. One or more outgroups are typically recognized and
increasingly opposed as the network becomes more tightly
organized.








26

5. A network is commonly identified with a leader who may
provide intellectual and/or organizational coherence.
The work that the network associates itself with generally has originated, or is centered on a particular place with a more or less well defined origin and time
span.


Some of the confusion and contradictions concerning succession may be attributed to a lack of understanding of the history and sociology of the succession concept and the origins and evolution of the competing paradigms, or conceptual models. Confusion often arises from ignorance, as proponents of a "new" view may be unfamiliar with early work in the field, current thinking within other groups in the field, or their nomenclature and terminology. The invisible college hypothesis may help explain the divergent positions in ecology specifically concerned with succession.

A scientific community upholds an old paradigm in spite of its inadequacies and contradictions until a new and better one emerges and is accepted. The paradigms of succession appear to be flawed and a new paradigm will likely emerge from a more eclectic synthesis. It is clear that an explanation of the cause and mechanism of succession, and development of a reasonable consensus on a paradigm of succession, will require a careful analysis of the historical background, biases and premises, and philosophy of the idea and its practitioners, critics, and proponents.

As a framework for formulating this bridging paradigm, McIntosh (1981) provided a number of questions to be answered:








27

1. Do the extended observations of succession support a
general theory of the successional process that is (a) orderly, directional and predictable; (b) controlled by biotic factors, (ie., autogenic); and (c) leads toward an equilibrium state in either or both its biotic or
abiotic attributes?

2. Is the claim of some ecologists that successional
phenomena are reducible to theories of natural selection justified? How do population theory and life history
strategies explain and predict ecosystem attributes?

3. What are the emergent properties claimed to justify
ecosystems theory? If population phenomena are not
additive, what is the measure of integration?

4. Does the evolution of ecosystems have any reasonable
explanation in evolutionary theory?

5. Is the reduction of ecosystem to trophic numbers, seen
by Hutchinson (1942) and Ulanowicz and Kemp (1979) as the essence of the genius of Lindeman, holistic or simply a collective property as stated by Salt (1979)? In what sense is the ecosystem approach to succession holistic?

6. Can reasonably explicit distinctions be made between a
small-scale disturbance initiating the traditional serule within the community and a large scale disturbance initiating an earlier stage of a sere? Can autogenic and allogenic disturbances be clearly distinguished or are
they interdependent, as suggested by White (1979)?

7. Can a theory of succession be developed to incorporate
a sere regularly reaching an equilibrium over an extended area, as argued by Bormann and Likens (1979) and Franklin and Henstrom (1981), and a sere that is largely interrupted by disturbance as described by Raup (1957) and by Heinselman (1981)? Can the achievement of equilibrium be related to a trajectory toward
equilibrium?


Hypotheses and Obiectives

Research for this dissertation involved nearly 4 years

of field work on mined lands in Polk County, Florida. The

main objectives were (1) to evaluate the process of initial








28

plant community establishment in wetland and terrestrial communities and interpret the results and observations through competing paradigms of succession (initial floristics, inhibition, relay floristics, coevolution, and selforganization), (2) to determine the role played by moundbuilding ants in the developing community and assess this role with the prevailing paradigms, and (3) identify possible techniques for enhancing succession on strip-mined land. These overall research objectives were addressed in three separate but related field studies.


Marsh Development


Seed bank survey. As an initial step in understanding and enhancing the design of self-maintaining ecosystems, seed bank dynamics were examined. A survey was made (1) to assess the size and species composition of seed banks in selected marsh ecosystems from natural and post-mining landscapes, (2) to identify the ecological role and significance of seed banks in marsh community dynamics, and (3) to evaluate the feasibility of establishing marsh ecosystems by helping form seed banks.


Marsh transect study. Transects were used to compare the herbaceous component of the wetland that developed from natural processes to that created by spreading muck from an onsite donor marsh. Stages of vegetation establishment were








29

examined to test the hypotheses that (1) differences in the initial floristics in the two treatment areas (mucked versus unmucked) result in communities of very different species composition and (2) differences in the perennial macrophytes of the two different treatment areas would be maintained through time.

Both seedbank and transect studies were used to evaluate the Gleasonian model of wetland succession proposed by van der Valk (1981).


Upland Forest Development


Upland forest studies examined the relationships between early colonizing plants and late successional trees on an unvegetated upland site. The colonizing annuals, biennials, perennials, and low shrubs found on old fields were designated early successional species. The interactions between early and late species were examined to determine which paradigms explained ecosystem development (inhibition, initial floristics, or relay floristics). Field plot experiments using species removal and addition were designed to determine the effect, if any, of colonizing vegetation on establishment, growth, and survival of tree species.

Four treatments were used: (1) natural colonization, (2) enhanced colonization with seeds of several common old-field weeds, (3) addition of legume species, and (4) periodic weeding to keep the plots generally free of any colonizing








30

vegetation. In both the enhanced colonization and enhanced legume treatments, the natural colonization process was also allowed to occur. Criteria for accepting or rejecting the competing paradigms are given below.

1. If seedlings grew better with either the enhanced
colonization, natural colonization or legume treatments, then the initial floristics and inhibition paradigms were
rejected in favor of the relay floristics paradigms.

2. If seedlings grew better in weeded plots, then the
initial floristics and relay floristics paradigm were
rejected in favor of the inhibition model.

3. If seedlings grew about the same in the weeded plot as
in other treatment plots, then the relay floristics and inhibition paradigms were rejected in favor of the
initial floristics.


Mound-Building Ants and Ecosystem Development


Early successional mined lands provide an opportunity to investigate interactions between species as the community is developing in a simple system with a few producers and a few consumers. Three field observations aroused interest in the role and effects of mound-building ants in such a system.

First, fire ants (Solenopsis invicta) are one of the earliest arriving invertebrate consumers on young strip-mined lands. In central Florida, fire ant populations were usually well established in the first year after mining ceased.

Second, herbaceous plants, especially grasses, growing on ant mounds were typically more robust, with a richer green color than plants found on adjacent non-mound soil. This








31

observation led to the hypothesis that mound soils were more fertile because of the ants.

Third, it was noted that overburden soils high in clay formed surface crusts that inhibited water infiltration, but mound building and tunneling by ants broke the surface crust and maintained the soil in a more friable condition.

Fire ants are omnivorous scavengers who forage the landscape, gathering food materials and returning with them to the mound. This activity concentrates otherwise dilute nutrient materials, which may be one of the primary functions of ants in the ecosystem. If ant mounds represent a localized concentration of nutrients in the form of insect parts, plant parts, feces, and waste products, then they are also likely to be foci of microbial activity mineralizing organically bound nutrients. The ant colony and mound system may recycle materials that are scarce in the developing ecosystem.

Mound-building ants may alter the soil profile and influence particle size distribution, bulk density, porosity, and infiltration capacity. These soil alterations may affect primary production.

Relationships are shown in diagrammatic form. Arrows on a causal loop diagram of the ant model indicate pathways of influence (Figure 4). A "+" used at an arrowhead indicates an increase in the adjacent item. For example, a larger concentration of food materials in the mound leads to a higher level of microbial decomposers. A "-" indicates a











H20 Infiltration
into Soil
++ +
Consumers 4r Plants

Inorganic Nutrients


Microbial
Changes in + Decomposers
Soil Structure
+ + + Concentration of Ants and --Food Materials Mound Building






Figure 4. Causal loop diagram showing feedback relationships between mound-building ants, plants, other consumers, water infiltration, soil development and nutrient cycle.








33
decrease in the item at the arrowhead. The ant model depicts two positive feedback loops, one linking plants-ants-microbes and one linking mounds-soil-water infiltration. The arrows represent causal relationships that can be experimentally evaluated.

An energy circuit language formulation of the ant model (Figure 5) also provided a summary of ecosystem components and energy/material pathways for directing research efforts. Research questions were:

1. Do mound-building ants concentrate nutrients in the
landscape?

2. If they do concentrate nutrients, does this provide a
feedback to the primary producers (plants), establishing a non-trophic interaction or indirect effect and
eventually a feedback to themselves?

3. What function does mound-building work serve for the
developing ecosystem?

4. If ants are found to provide positive feedback to the
developing ecosystem, are there ways to further stimulate
feedbacks and enhance succession?



Description of Study Sites


Eight study sites in central Florida were used in the three phases of the research (see Table 1 and Figure 6). Seven of the sites were within Polk County and one in the northeast Manatee County in the Four Corners area. A brief description of each site is provided below.

Pasture Marsh. This marsh was approximately 1.0 hectare in size and located on the Mobil Chemical Company's





























Figure 5. Energy circuit language diagram of ant model.





35























I\








36

Table 1. Sites used in marsh study, upland forest study, and
ant study.




Upland
Marsh Forest Ant Sites Study Study Study


Sanlan Marsh X Tiger Creek X
Reclamation Area

Clearsprings Wetland X X
Demonstration Project

Whidden Creek X
Reclamation Area

Four Corners Wetland X
Demonstration Project

Fort Green Wetland X X
Demonstration Project

Natural Marsh X Peace River Bay Swamp X







37


\A


Lake Kanapaha










i LAKELAND .92


:::Hancock
ii
9817

Sanian Mine BARTOW Clear Springs Mine Tiger Bay MineA 64

37

FORT MEADE
-630 * e* Whidden A Pasture Marsh ACreek A Bay Swamp A Pt Green Mine Mine

2 Pok count
Four Hardee County
CornersA "


~I
Mine C





Figure 6. Location of study sites in Polk and Manatee
Counties.








38

South Fort Meade Mine tract. The vegetation within the marsh was dominated by softrush (Juncus effusus), pickerelweed (Pontederia cordata), Saqittaria lancifolia, and smartweed (Polygonum punctatum). The marsh was selected as typical of the freshwater marshes within the study area, most of which are subject to grazing.

Peace River Bayhead. This bay swamp is located on a seepage slope draining to the Peace River on Mobil's South Fort Meade Mine tract. The swamp had an overstory of sweetbay magnolia (Magnolia virginiana), red bay (Persea palustris), and dahoon holly (Ilex cassine). The groundcover consisted primarily of lizard's-tail (Saururus cernuus). The substrate consisted of a layer of finely decomposed muck overlying fibrous peat. The depth of the organic soil averaged approximately 1 m.

Sanlan Marsh. This marsh developed on an unreclaimed clay settling area that was mined in the early 1950's. The site was selected because it was one of the few old, unreclaimed clay settling ponds that was not dominated by cattail, primrose-willow, or willow.

Four Corners Demonstration Project. W.R. Grace Company initiated a wetland reclamation demonstration project at its Four Corners Mine site in 1979. Four 0.16-ha depressions were excavated to a maximum depth of 1.2 m in a pine-palmetto flatwoods adjacent to Alderman Creek in 1978. The area was not mined, but overburden was removed to a depth below the










minimum design grade and then backfilled, simulating reclamation. Four test plots were established as follows:

1. Plot 1. Control plot, graded and left for natural
revegetation.
2. Plot 2. Hand-planted with plant material taken from
nearby natural marsh, including maidencane (Panicum hemitomon), pickerelweed (Pontederia cordata), and Juncus
effusus.

3. Plot 3. Mulched 30 cm deep with donor muck from a nearby
marsh.

4. Plot 4. Tree plot where 95 trees comprising 16 different
species were transplanted from a donor site on Alderman
Creek.

Whidden Creek Reclamation Area. The Whidden Creek area was mined by Gardinier Phosphate in 1982 and 1983. The area was reclaimed in 1983 using an integrated landscape approach, that sought to create a small drainage basin discharging to Whidden Creek.

Tiger Bay Reclamation Area. The Tiger Bay area was mined by International Chemicals and Minerals, Inc. (IMC) in 1982 and 1983. The area was reclaimed in 1983 as a land-and-lakes area typical of the industry's reclamation practice.

ClearsDrings Wetland Demonstration Project. Work on this 18-ha wetland demonstration project began in 1978. The project was a joint effort of IMC, the Florida Game and Freshwater Fish Commission, and the U.S. Fish and Wildlife Service. The site adjoins the Peace River and was designed to establish physical site characteristics similar to those that produce and maintain floodplain wetlands. Basins were








40

created to encourage emergent plants, store water onsite, and create fish and wildlife habitat. Test plantings of 15 different tree species, planted as bare root seedlings were done in 26 plots with 400 trees per plot. Freshwater macrophytes were also planted in the basins.

Fort Green Wetland Demonstration Project. This wetland project is part of a 148-hectare reclamation project carried out by Agrico Mining Company at its Fort Green Mine in southwestern Polk County (Figure 6). The site, which was mined in 1978 and 1979, was recontoured to create 61 ha of wetlands and 87 ha of uplands (Figure 7). The reclamation began in 1981 and was completed by May 1982. The project sought to create open water, freshwater marsh, freshwater swamp, and upland habitat.

The site is gently sloping with a range of 40.23 m down to 35.40 m mean sea level (msl) in the wetland basin. The wetland basin receives runoff and baseflow from the surrounding uplands. The basin has a highwater discharge to the adjacent floodplain of Payne Creek when the surface water elevation reaches approximately 36.58 m msl. Within the wetland basin are several deep holes that serve as deep water habitat and aquatic refuge during times of drought. These deep pools have spot elevations ranging from 31.85 to 35.36 m msl.

The donor muck was transported from a nearby donor marsh and spread in the littoral zone with depth varying from 2.5









41

to 30 cm. Approximately 15 percent of the littoral zone received the muck treatment.



















Pond



Transida Zon








Transition Zone wswad I Trani o oZon




Wagend





ZonEde Much Zone 0 100m 200m soonlow aas



Figure 7. Fort Green wetland reclamation area showing marsh transect locations, approximate vegetation zones, and muck treatment zones.














METHODS


Marsh Development

Seed Bank Survey


The seven wetland sites sampled in the seed bank survey include natural wetlands, and unreclaimed and reclaimed wetlands on mined lands (Table 2 and Figure 6). At each site, one to several major vegetation zones were sampled with a 5-cm diameter, hand core sampler that was pushed into the substrate to the mineral soil layer. The depth of any overlying organic layer was noted, and only the upper 10 cm of the core was retained. Four individual cores were combined to yield a composite sample, with three composite samples taken in each vegetation zone selected. Samples were stored in sealed plastic bags at 4*C until they were processed.

All live plant material was removed from the samples to prevent confusing in seed germination results with any vegetative regeneration. Once the plant material was removed, the samples were placed in wooden flats (25 cm x 25 cm) containing approximately 4 cm of sterilized gravel mixed with tailings sand; the samples were approximately 2 cm deep when spread out evenly in the flats. The flats were then placed




43





Table 2. Sample locations and site characteristics.


Site County Vegetation Zone Substrate


Unreclaimed Mine Site

Sanlan marsh (30 yr old) Polk Juncus-Polygonum Clay Eichhornia Clay

Reclaimed Mine Sites

Clearsprings (4 yr old) Polk Polvqonum-Ludwiia Clay-overburden Fort Green (2 yr old) Polk Pontederia (Muck zone) Muck-overburden Open water (Muck zone) Muck-overburden Open water Overburden Four Corners Marsh Manatee Pontederia (Muck zone) Muck-sand
(5 yr old) Pontederia (Planted) Sand Eleocharis (Control) Sand Polvygonum-Ludwiqia Sand

Natural Wetlands

Pasture marsh Polk Pontederia-Juncus Muck-sand
Peace River bayhead Polk Sayurrus Peat
Lake Kanapaha * Alachua Amaranthus Muck-sand Echinochloa Muck-sand Open water Muck-sand Four Corners marsh Manatee Pontederia-Juncus Muck-sand


* Lake Kanapaha not sampled in this study, results from previous study provided by Dr. Ronald Myers








45

outdoors in large plastic tubs containing sufficient water to maintain a saturated soil condition.

Seedling emergence by species was monitored through time. Unidentified seedlings were counted, transplanted to flower pots, and allowed to mature until they could be identified.



Marsh Transect Study


Six permanently marked transects were established in October 1982: three each randomly located within the muck treatment areas and the unmucked, overburden areas (see Figure 7). All transects began in the shallow littoral zone and extended upslope through the transition zone to the upland edge. The three muck treatment transects totaled 309 m and the three overburden transects totaled 275 m. The difference in total length of the two treatment groups was a result of the slope differences at the random locations.

The plant communities along the transects were monitored using a modification of the standard line-intercept method (Phillips, 1959; Smith, 1980; Canfield, 1941) to record the percent cover by species along each transect. The standard method consists of taking observations along a transect line and noting the identity of any plant touched by an imaginary plane extending vertically above and below the transect line. The distance, or interval, of the planar intercept is also recorded. The individual intervals are totaled for each








46

species to yield total cover, which can be standardized to percent cover.

The modification of the standard method used in this study consisted of identifying patches or intervals of species occurrence even when the cover by the particular taxa within the patch was less than 100 percent. With this modified lineintercept technique, the interval distance as well as the percent cover by the taxa within the interval was recorded. The modification provided a more rapid method of measurement that was also relatively accurate and well adapted to measuring changes in vegetation across zones and following changes through time.

The transects were sampled over four growing seasons: November 1982; May, July, and November 1983; March, July, and November 1984; and June 1985.

Elevations along each transect were measured on 1.5 m intervals. These elevations were converted to mean sea level (msl) based on a reference to the measured surface water level in the wetland basin that day. A continuous water level record was provided by a surveyed, permanently mounted water level recorder. The daily summary values for the period of study were supplied by Agrico Mining Company.








47

Upland Forest Studies


An upland area on the west side of Parcel 6 at Gardinier Phosphate Company's Whidden Creek Mine (Figure 6) was cleared in late October 1983. The cleared area was 63 m by 63 m with a gentle slope from the south to the north. Seedling and direct-seeded plots were located in early December 1983 and two experiments were set up adjacent to each other (Figure 8). The experimental design was a nested analysis of variance with four experimental treatments: colonizing species allowed, colonizers weeded out, colonizers added, and legumes added. Within each of the two experiments were four replicates for each treatment, for a total of 32 plots. All treatments were randomly assigned to plots.

The experimental treatments used in both the seedling and direct-seeded plots were the addition of seed of four colonizing species, the addition of seed of four legume species, the removal of all colonizing species through weeding, and a natural invasion of colonizing species. The first two treatments involved the application of seed, which was completed just prior to planting the tree seeds or seedlings. The initial site clearing in October left all plots free of vegetation at planting time.

The enhanced colonizer treatment included four of the most common species found on old fields and abandoned mine lands in central Florida: natal grass (Rhvnchelvtrum revens),






48



Seedling plots Seed plots

E E C W E L W E C W E L
C W L C W C L
L C L L E W L E C E

C W E Enhanced colonizers
L Legumes added
C Natural colonizers allowed
W Weeded





Seed plo wis wbt Figure 8. Schematic layout of seed and seedling transplant plots on upland study site at Gardinier's Whidden Creek Mine area.








49

groundsel (Baccharis halimifolia), dogfennel (Eupatorium capillifolium), and broomsedge (AndropoQon virginicus).

Four species were added in the enhanced legume treatment: Cassia obtusifolia , Sesbania macrocarpa, Sesbania punicea, and Sesbania vesicaria. In the direct-seeded plots, 50 seeds of each legume were added for a total of 200 seeds per plot; 110 seeds per legume, totaling 440 seeds per plot, were added to seedling plots receiving this treatment. In both cases, the seeding rate gave a density of 22 legume seeds/m2.

Seeds for the enhanced colonizer and enhanced legume treatments were applied by mixing the seeds with some overburden soil from the plot and hand broadcasting the mixture onto the plots. The soil was disturbed by hand with rakes and cultivators, to mitigate the effects wind would have on surface spread seeds of these wind-dispersed species. All plots were subsequently disturbed as part of a preplanting treatment. Planting and preplanting treatments were carried out in December 1983.

The weeding treatment was administered quarterly in March, May, June, and September for both the transplanted and direct-seeded plots. All colonizing plants were hand-weeded and removed from the plots.

Heavy rains in the first month after planting created several erosion rills running through the plots. To prevent cross contamination by seeds washing out of one plot and into another, hay was spread on the magins of all plots that had








50

downslope neighbors. All major erosion rills on the site were mapped as an aid to interpreting results. In addition, several rills that had developed through the seed plots were diverted to interplot areas with a shallow, diversion trench. Once colonizing vegetation began to appear in early spring of 1984, it afforded a modest degree of soil stabilization and the severity of the erosion diminished considerably.


Direct-Seeded Plots.


Seeds of seven species were used in the direct-seeded test plots seeds: sweetgum (Liquidambar styraciflua), cabbage palm (Sabal palmetto), live oak (Quercus virginiana), laurel oak (Quercus laurifolia), southern magnolia (Magnolia Qrandiflora), sugarberry (Celtis laevicata), and pignut hickory (Carva glabra). These seven taxa were considered representative of common mesic hardwood species of central Florida.

The seeding rate per plot was 50 seeds per species, yielding 350 seeds per plot. Each plot planting area was 9 m2 (3 m by 3 m), resulting in a density of 39 seeds/m2.

The plots were arranged in a 6 by 3 grid with two of the plots remaining unused (see Figure 8). Treatments were assigned randomly to the plot grid. Each total plot was 7 m by 7 m, which allowed for a 2-m buffer all around the 9m2 planting area. The seed mix was hand broadcast onto the plots after the soil was disturbed, and the treatment seeds were








51

added if required were. The plots were then raked lightly to incorporate the seeds into the substrate.

The seed plots were measured in March and October 1984 and the species, height, and growth condition of each seedling in each plot was recorded. The location of each seedling was recorded as well so the fate of individuals could be followed.


Seedling Transplant Plots

In the seedling test plots, three mesic hardwood species were used: sweetgum, live oak, and cabbage palm. The planting stock for sweetgum and cabbage palm was 8-month-old containerized seedlings grown in overburden soil. The oak seedlings were 1-month-old bare root seedlings.

Ten individuals of each species were used in each of the 16 seedling plots, yielding 30 trees per plot and 480 seedlings total. Tree seedlings were planted after the soil was disturbed and any treatment seeds were added. The 30 trees were randomly assigned to the grid, and the same planting schematic was used in all the plots (see Figure 9).

The total area of each seedling plot was 8 m by 9 m, allowing for a 2-m buffer around an actual planted area of 4 m by 5 m. Seedlings were planted on approximately 1-m centers.

The severe winter freezes of December 1983, and January February 1984 killed many of the planted seedlings. As the





52






S C L L C S L C S S C S L S S L L L C S C L L C C S C S C L

Seedlings planted on im centers

C Cabbage Palm
S Sweetgum
L Live Oak



Figure 9. Schematic for planting in Gardinier seedling plots.








53

freezes occurred before any possible treatment effects could have been exerted, all of the freeze-killed seedlings were replanted on March 27, 1984, which was then used as the starting date for growth measurements on the seedling plots. The plots were measured again in September 1984. At the time of measurement, the height of each seedling and growth condition were recorded.

Mound-building Ants and Upland Succession


Survey of Mound Density

Mound densities on the 1-year old IMC Tiger Bay site, the 2-year old Agrico Fort Green site, and the 5-year old IMC Clearsprings site were sampled. Replicate 5 m by 5 m plots were semi-randomly located at each site, and the location, diameter at base, height, general condition, and level of ant activity of each mound within each plot were recorded. Physical Soil Analyses


Bulk density. Bulk density of mound and non-mound soils at the Fort Green Payne Creek site was sampled with a bulk density core sampler. Seven mound and seven non-mound samples were taken. The samples were oven dried at 1030 C until a constant weight was attained, and the density was determined based on the volume of the sampler and its oven-dried weight.








54

Infiltration tests. Soil water infiltration differences were measured at the Fort Green site using the paired infiltrometer technique (Bertrand, 1965). A metal cylinder, 16.5 cm in diameter and filled with water, was used to measure the rate of water intake of the soil. The metal cylinder was placed on the ground and driven into the soil with a rubber mallet to a depth of approximately 5 cm. A circular berm approximately 10 cm high and 60 cm in diameter was then created around the metal cylinder. The area enclosed by the berm served as the outer cylinder. Both cylinders were maintained at approximately constant head, or depth, by the addition of water. The amount of water lost through the inner cylinder over a measured time interval provided an estimate of the infiltration rate. The infiltrometer test was not designed to measure absolute infiltration rates but rather as a measure of relative infiltration rates in side-by-side comparisons. Three such comparisons were made. The first used three infiltrometers, with one placed over an ant mound, one on an adjacent grassed area typical of the site, and a third on a bluegreen algae flat. This test was run for 120 minutes. The second test, which lasted 60 minutes, compared the rates of another ant mound and another "typical" grassed area. The third test, which lasted 20 minutes, paired another mound and "typical" grassed area.








55

Chemical Soil Analyses


To test the hypothesis that the activity of the fire ants changes the chemistry of the mound soil relative to the nearby soil, paired soil samples were taken at the Tiger Bay, Fort Green, and Clearsprings reclamation sites. Each reclamation area consisted of recontoured overburden. Six paired samples were taken, each pair consisting of a mound sample and nonmound sample from 1 m away, were taken at each site. All samples were taken with a bucket auger and stored in plastic bags at 50 C.

Samples were air dried and sifted through a No. 20 mesh sieve to remove ants from the mound soils. A subsample of approximately 100 g was taken from the sieved samples to be used for chemical analysis. The remaining soil was composited to yield single mound and non-mound sample from each of the three sites. The composite samples were used for greenhouse experiments assaying growth differences between the two soils.

Individual soil samples were analyzed for pH, organic matter content, total kjeldahl nitrogen (TKN), and selected cations (calcium, magnesium, potassium, sodium, and manganese).

pH measurements were made with a pH meter with glass electrode in a 2:1 deionized water to soil dilution, using 10 g of air-dried soil mixed with 20 ml of distilled water.








56

Soil organic matter was determined by the Walkey-Black wet digestion method (Black, 1965).

Nitrogen was measured as TKN by the semi-micro kjeldahl procedure, a 1-g sample of air dried soil 7 ml of sulfuricsalicylic acid was added. After each sample was allowed to set for 30 minutes, 1 g of sodium thiosulfate was added and 2 g of catalyst were added. The samples were then heated in a block digester for 5 hours. After digestion, 20 ml of NaOH, 15 ml of boric acid, and 2 drops of indicator were added to each sample. The samples were then distilled to 60 ml, and titrated with 0.05 normal sulfuric acid.

A dilute double acid solution (0.025 N H2SO4 + 0.050 N HCl) was used to determine extractable levels of calcium, magnesium, manganese, potassium, and sodium. Cation levels in the extracts were measured by atomic absorption-emission on a Perkin-Elmer model 500 using standard operating techniques (Perkin Elmer, 1980). One ml of a 10,000 ppm (1%) lanthanum chloride (LaCls) solution was added to each dilution series of extract, which resulted in a 1000 ppm solution (.1%) in each sample. This procedure was necessary to control for interferences by silicon, aluminum, phosphate, and sulfate, which depress sensitivity in analyses for these cations. Equal amounts of lanthanum chloride were also added to standards and controls before analysis.








57

Plant Growth Study


Several greenhouse experiments were set up to evaluate a potential growth difference between plants grown on mound and non-mound soils. The tests used a common early colonizing grass, vaseygrass (Paspalum urvillei), and a woody plant, sweetgum (Liquidambar styraciflua), as the assay organisms.

The composite soil samples, as described above, were used in the growth experiments. Ten plastic seedling tubes were filled from each of the six composite samples ten plastic. In each group of ten seedling tubes, five received a seedling of vasey grass and five received sweetgum. The tubes were placed in a greenhouse.

At the end of 60 days, the seedlings were harvested and dried at 1030 C to a constant weight. Each vasey grass seedling was subsequently divided into above- and belowground portions that were weighed separately. The sweetgum seedlings were divided into root, stem, and leaf components, each of which was weighed separately. Leaf area of each sweetgum seedling was determined by making a xerographic image of the leaves, cutting out the individual images, and measuring leaf area with an automatic area meter.








58

Statistical Analyses


All statistical analyses were run with the Statistical Analysis System (SAS). Data expressed as percent were transformed by the arcsine function.













RESULTS


Marsh Development


Seed Bank Survey


Results are presented in four general areas: seed bank density, species importance values, floristic similarity between samples, and species diversity of samples.

Seed bank densities. The mean number of seeds germinating in samples from natural, reclaimed, and unreclaimed marshes in central Florida ranged from 1877 to 72,500/m2 (Table 3). For comparison, seed bank studies of natural wetlands from Florida, Iowa, New Jersey, and Ontario have shown a range of density from 6,000 to 156,000 seeds/m2 (Table 4). The overall range of seed bank size (density) covers three orders of magnitude; the lowest density is 1877/m2 in the sample mucked-unvegetated zone at Fort Green and the high value is 156,000/m2 from the Sacciolepis striata zone at Lake Kanapaha, Florida.

The range for natural wetlands samples is 4,000 to 156,000 seeds/m, with the lowest value from the Peace River bay swamp (the only forested wetland sample) and the high value again for the Sacciolepis zone at Lake Kanapaha. A trend evident in the results from studies at Lake Kanapaha is


59









Table 3. Mean number of germinating seeds per m2* by species for natural wetlands and reclaimed and unreclaimed marshes in central Florida phosphate district.


four Sanlan four Corners Clear Sorinsa fort Green
Coraers
Bay lateral Pasture JncII- Topsoiled Planted Control Pleated South South lorth Topsoiled, Topsoiled, Seanp larsh larsh oalatan lichania larsh larsh larsh S Saop Basis II Basis 12 Basisle letated havegetated Iaenlched

ar ahlat --. --- --- --- -- --- --- --- --- 416 50 21 --- --hckalL ikfil --l- --- --- --- --- --- -- ...-- 125 42 22 --- -Cwra sp. --- --- --- --- 125 --- --- -- --- ... ... ... --- --- --M n cl igJ i --- ..... 1 ... --- --- 14 --- ... . --- --...C p. --- --- --- - --- --- ...-- --- ----.. --- - --. 915 334 6
ClmaratLud an 4 --- --- 41 3,150 16 --- --- 500 1,66 1,.125 1,500 --- --ra t 1 --- --- --- --- ... -- --- --- --- -- --- --Ichlockla s ...i. --- --- --- --- --- --- --- --- -- --- --- --- --- 125
killl k --- --- --- 125 --- --- --- --- --- 250 541 42 --- --- --IutAiIcopoalitifolini 84 --- --- 541 --- --- --- 125 46 125 251 315 --- 42 84
rahAhls obta ialiolln --- --- --- --- --- ... ... ... ... ... .....
ralsses, ahos --- --- 42 --- --- --- -- --- --- 125 --- --- ... .........
12 --- --- --- --- --- ... -- --- 42 --- --- --- --- --83 --- --- --- --- ... .. 14 ... ... ... ...--- --- ......
I4 42 --- --- --- --- --- --- --- --- --- 25 125 --- --I5 --- --- --- ... ... ....-- --- ---1,6 --- --- --- 1,25--I6 --- 42 84 --- --- ... ... ... --- --- ... --- --- --- --Irdllcola verticillata (2 --- --- --- ... ..- --- --- --- ... ---...
~riam utila 42 --- --- --- --- --- --- --- --- --- --- 1 ...
ans ffllauu 292 67,210 40,132 58,625 1,25 32,150 31,016 1,500 10,625 1,815 1,815 1,16 146 20 42 1,210 si hafoalat 125 ..--- --- 42 --- 42 .. --- --- ... --- --- --- --AIiI ll 292 --- --- --- --- -- --- --- 500 416 2,666 1,834 1,315 1,416
LAdhW allsri 33 --- --- -- .... . ... 42 - --- --- ......
LhdAl t latDtCA --- --- --- --- ...- - -... --- --- 4 210 --- --- ...
PAIIONani nactia --- 5,250 292 2,460 125 42 126 --- 42 42 125 84 Eilaiein evllacea --- --- --- --- -...... 12 1,142 84 --- --lMu wertieillates .--- --- - ... .. --- --- 42 --- --- ---...
salaI p artilotr 25 --- --- --- --- --- --- --- --- --- --- 42 ...... --Srolalarlacea ? --- --- --- ... ... --- --- --..- --- 42 ...
ltallait tiA --- --- ...--- ---... --- ...--- ---... 331 ... . --- --- ---...
lakho species $1 --- --- --- --- --- --- --- --- --- 3715 1,134 2,150 315
12 --- ..--- --- --- --- --- I4 250 42 ... --- --- --- ... ...
3 2,541 ---.. --- -- --- ---.. --- --- --- ..--- --- 14 12

lean 8 seeds/a2 4,125 12,502 41,2l 82,255 12,04 12,04 33,0 31,710 2,210 11,40 1,315 11,300 ,l8 3,334 1,11 3,120 1 species 11 3 4 S 5 4 4 4 1 IS 13 14 4 5 6


Results fron core samples 1i Cs deep ilth actual area sampled corrected to steadard reference area of I m, 0









61
Table 4. Seed bank densities, species richness, and
Shannon-Weaver diversity index from Florida
wetlands and selected marsh studies from
temperate North America.

Mean # Number of Shannon-Weaver seeds/ Species Diversityf' Source

Natural Systems. Florida

Bay Swamp 4,125 12 1.45 This study Lake Kanapaha
Saccioleoiszone 156,000 38 2.64 Myers 1983 Amaranthus zone 28,000 17 1.72 Myers 1983 Echinochloa zone 30,000 13 0.98 Myers 1983 Pond zone 9,000 8 1.17 Myers 1983 Four Corners Marsh
Juncus-Pontederiazone 72,502 3 0.06 - This study Pasture Marsh
Juncus-Pontederia zone 41,250 4 0.26 This study Unreclaimed Systems
Sanlan
Juncus-PolvoonumMarsh 62,250 6 0.30 This study EichhorniaMarsh 12,040 5 0.86 This study Reclaimed Systems
Four Corners Reclamation Project Mulched plot 33,000 4 0.05 This study Planted plot 31,710 4 0.05 This study Control plot 2,210 4 0.95 This study Planted swamp plot 11,460 4 0.30 This study Clearsprings Reclamation Project South Basin #1 7,375 16 2.03 This study South Basin #2 11,300 13 1.92 This study NorthBasin 9,880 14 1.88 This study

Fort Green Reclamation Project
Mulched, vegetated 3,334 4 1.11 This study Mulched, unvegetated 1,877 5 0.84 This study Unmulched 3,920 6 1.38 Thisstudy

Other Natural Systems
Iowa, Prairie
glacial marsh 20-40,000 7-16 Not calculated van der Valk and Davis (1976, 1978)
Ontario, Lakeshore
marsh 9-20,000 31 Not calculated Keddy and Reznicek (1982)
New Jersey, Freshwater
tidal marsh 6-32,000 12-20 Not calculated Lock and Graveline -(1979)








62

that the species richness and size of the seed bank appear to decrease as the water depth increases in the Sacciolepis zone-Amaranthus zone-Echinochloa zone-Pond zone (Table 4). For the wetland samples cited from outside Florida, the densities range from 6,000 to 40,000/m 2, and for the three natural systems sampled in this study, the range of densities is 8,000 to 72,000/m2. The two marsh samples (Four Corners natural marsh and pasture marsh) had densities of 41,000/m2 and 72,500/m2, respectively.

The unreclaimed wetland sampled, the Sanlan marsh, had densities of 12,000/m2 and 62,000/m2 from the Eichhornia and Juncus marshes, respectively. As with the Kanapaha samples, seed bank size apparently decreases with depth (water depth is more than a meter in the Eichhornia marsh). The Sanlan samples, especially the Juncus-Polygonum zone with 62,000/m2, fall in the range of the natural wetlands already discussed, thus representing some of the higher densities encountered. This indicates that sizeable seed banks can develop in the absence of any reclamation efforts in post-mining wetlands.

Wetland samples from reclaimed mine lands had a range of 1,800 to 33,000/m2, which is low to moderate by comparison to natural wetland systems. Samples from the three basins at Clearsprings ranged from 7,000 to 11,000/m2; at the Four Corners project, the range was 2,200 to 33,000/m2. More specifically, the treated plots had densities well within the range of the natural systems: topsoiled (peat) marsh plot








63

(33,000/m2), planted marsh plot (31,000/m2), and swamp planted plot (11,300/m2). The lowest density found at the Four Corners project came from the control plot (2,200/m2), indicating that seed bank establishment is facilitated by reclamation efforts.

Samples from the Fort Green project had the lowest and narrowest range of densities (1,800 to 3,900/m 2), but it should be remembered that this project is only in its second growing season. Surprisingly, the lowest density value from Fort Green, and for all samples, came from an unvegetated topsoiled (peat) area with open water. This may be a result of the vagaries of sampling; alternatively, the seed bank in the peat at this spot may be dominated by short-lived seeds or species that only germinate under flooded conditions (which were not duplicated in this study) or the topsoil material (peat) may have been stockpiled (as is known to have occurred with some peat material at this site).


Species importance values. As an estimate of the overall influence or importance of each species in the seed bank survey, modified importance value were calculated from the density and frequency totals (Table 5). The importance value is calculated by adding relative density and relative frequency for each species, where relative density as the density of the species divided by the sum of all densities, and where relative frequency is defined as the frequency of









64

Table 5. Seed bank density data from Table 3 summarized across sites for species totals of density, relative density, frequency, relative frequency, and importance value.





Density % Sampling % Total Relative Site Relative Importance (mean #/aZ) Density Frequency Frequency Value

Aster subulata 1,126 0.36 0.20 2.80 3.16 Baccharis
halimifolia 459 0.15 0.20 2.80 2.95 Career sp. 125 0.04 0.07 0.95 0.99 Cynerus brevifolius 500 0.16 0.13 1.90- 2.06 CYDerus sp. 2,209 0.70 0.20 2.80 3.50 C Yerus rotundus 12,207 4.00 0.53 7.50 11.50 Cyeraceae ? 84 0.03 0.07 0.95 0.98 Echinochloa walteri 125 0.04 0.07 0.95 0.99 Eclita A= 958 0.30 0.27 3.80 4.10
Euatorium
comoositifolium 1,672 0.50 0.60 8.50 9.00 Grachalium
obtusifolim 84 0.03 0.07 0.95 0.98 Grasses, unknown #1 167 0.05 0.13 1.90 1.95 Grasses, unknown #2 42 0.02 0.07 0.95 0.97 Grasses, unknown #3 84 0.03 0.07 0.95 0.98 Grasses, unknown #4 417 0.13 0.20 2.80 2.93 Grasses, unknown #5 1,625 0.50 0.07 0.95 1.45 Grasses, unknown #6 126 0.04 0.13 1.90 1.94 Hvdrocotvle
verticillata 42 0.02 0.07 0.95 0.96 HYDericum mutilum 206 0.07 0.13 1.90 1.97 Juncus effusus 257,587 84.00 1.00 14.00 98.00 Juncus bufonius 209 0.07 0.20 2.80 2.87 Ludwiaia virgata 8,499 3.00 0.47 6.60 9.60 Ludwiaia palustris 376 0.12 0.13 1.90 2.00 Ludwiaia lentocarna 294 0.09 0.13 1.90 2.00 Polvaonum punctatua 8,588 3.00 0.67 9.50 12.50 Ptilianium
capillaceum 1,168 0.40 0.20 2.80 3.20 Rmex verticillatus 42 0.02 0.07 0.95 0.97 Samolus arvilorus 292 0.09 0.13 1.90 2.00 Scrohulariaceae ? 42 0.02 0.07 0.95 0.95 Stellaria medla 334 0.10 0.07 0.95 1.00 Unknown species #1 5,334 1.70 0.27 4.00 5.50
#2 376 0.10 0.20 2.80 2.90 #3 2,750 0.90 0.20 2.80 3.70

Column total 308,000 100.00 7.07 100.00 200.00








65

occurrence of the species divided by the sum of all species frequencies. Both relative density and frequency were connected. With this type of calculation, both relative frequency and relative density are constrained to values between 0 and 100 percent, which produces an importance value for each species in the range 0 to 200.

The most striking aspect of the calculations was the numerical dominance of soft rush (Juncus effusus), which accounted for 84 percent of the germinating seeds in the study. It was also the only species found in all samples, yielding an absolute frequency of 1.0.

The 20 species of highest importance value account for 92.5 percent of the total importance value (see Table 6). In fact, the four species of highest importance value soft rush, smartweed (Polygonum punctatum), Cvyperus rotundus, and Ludwigia virgata account for 94 percent of the relative density and 66 percent of the total importance value. These four species can be considered the dominant species in this study and serve in general to characterize the seed banks sampled from central Florida.

Floristic similarity. Floristic similarity of seed bank samples was measured using the similarity index of Czekanowski for binary data. The index is defined as follows: Czekanowski's index = 2a/(2a + b + c) where a = species common to sites 1 and 2, b = species found at site 1 but absent at site 2, and c = species found at site








66

Table 6. Twenty species with highest importance values (IV) along with the relative density and relative frequency values used to calculate the IV. All data taken from Tables 3 and
4.



% %
Relative Relative Importance Species Density Frequency Value

Juncus effusus 84.00 14.00 98.00 Polygonum punctatum 3.00 9.50 12.50 Cvperus rotundus 4.00 7.50 11.50 LudwiQia virqata 3.00 6.60 9.60 Eupatorium compositifolium 0.50 8.50 9.00 Unknown 1 1.70 3.80 5.50 Eclipta alba 0.30 3.80 4.10 Unknown 3 0.90 2.80 3.70 Cyperus sp. 0.70 2.80 3.50 Ptilimnium capillaceum 0.40 2.80 3.20 Aster subulata 0.36 2.80 3.16 Baccharis halimifolia 0.15 2.80 2.95 Grass 4 0.13 2.80 2.93 Unknown 2 0.10 2.80 2.90 Juncus bufonius 0.07 2.80 2.87 Cyperus brevifolius 0.16 1.90 2.06 Ludwigia palustris 0.12 1.90 2.02 Ludwigia leptocarpa 0.09 1.90 1.99 Samolus parviflorus 0.09 1.90 1.99 Hvyericum mutilum 0.07 1.90 1.97

185.00








67

but absent at site 1. The index has a range of 0 to 1.0, where 0 represents complete dissimilarity and 1.0 represents complete similarity.

There were few cases of high floristic similarity (Figure 10). One was a comparison between the two natural marshes sampled and another between the Sanlan Juncus marsh and the Four Corners mulched plot, both of which compare samples of with low species richness. The other cases of high floristic similarity are within-site sample comparisons, one from Clearsprings and one from Fort Green.

The Clearsprings samples had the largest number of species and had moderately high to high within-site floristic similarity. The species assemblage at Clearsprings had several unique or less frequently encountered species, including Aster subulata, Baccharis halimifolia, Eclipta alba, and Ptilimnium caDillaceum. The samples from Fort Green also exhibited moderately high to high within-site floristic similarity, largely due to three species (soft rush, Ludwigia virgata, and a species of Cvperus).

Many comparisons of low to moderate similarity are noted, primarily because of the near ubiquity of soft rush and smartweed in all samples (Figure 10).


Species diversity. Species richness and species diversity were compiled from data from this study and from Lake Kanapaha (Myers, 1983) (Table 4). Diversity was
























Figure 10. Summary matrix of floristic similarity between seed bank samples.
















BAY SWAMP-.

FOUR CORNER MARSH

PASTURE MARSH ......


SANLAN- g . . .......


FOUR CORNERS MULCHED ......... FOUR CORNERS PLANTED ......... . PERCENT FLORISTIC SIMILARITY FOUR CORNERS CONTROL . . . . . . . . . ..................

:: :80-100 high
FOUR CORNERS SWAMP ..................................

CLEARSPRINGS SOUTH BASIN I ......... . 60-79 mod. high

CLEARSPRINGS SOUTH BASIN 2 459.. .
40-59 moderole
CLEARSPRINGS NORTH BASIN... ....................................

FORT GREEN MULCHED VEGET . . . ................mod. low............

FORT GREEN MULCHED UNVEGET ....... ............... . . ........ 0-19 low
L__*J0








70

calculated using the Shannon-Weaver diversity index, given as H' and defined as

H' = - (Pi In Pi)

where Pi is the ratio of the number of individuals of the ith species divided by the total number of individuals in the sample. The value of H' is influenced by two factors: the number of species, known as species richness, and the equitability with which the individuals of the population are apportioned among the species. The greater the species richness or the equitability the greater the value of H'.

The overall range of H' values was 0.05 to 2.64; the lower value was from the mulched, vegetated plot at Fort Green and the highest from the Sacciolepis-zone at Lake Kanapaha. The latter sample also had the highest seed density (156,000/m2) and the highest species richness (38).

The samples with the greater number of species typically had H' values in the upper range (see Table 4). The most diverse natural wetland samples came from Lake Kanapaha and the bay swamp, while the highest diversity in the mined wetlands group was in the Clearsprings samples. In several cases (Four Corners natural marsh, pasture marsh, Four Corners mulched plot, Four Corners planted plot, and Sanlan Juncus-zone, the seed bank had relatively few species and was dominated numerically by soft rush. This situation more or less defined the low end of the H' range.








71

Seed bank samples from all but the youngest sites in the post-mining landscape fall within or just below the range of densities and species diversity found in natural wetlands of Florida, Iowa, New Jersey, and Ontario. The indications from the results in this study are that it is possible for nature to reestablish a seed bank of approximately the same size and diversity as that occurring in some natural marshes, such as with the Juncus-Polygonum marsh at Sanlan (30 years old). The time required for the seed bank to become a "reasonable facsimile" of a natural marsh as yet may be undefined. The results at Clearsprings indicate that modest sized seed banks with higher diversity can develop in 4 years with little actual marsh reclamation. With some reclamation efforts, seed banks that compare very favorably in size with natural marshes can develop in 5 years, as demonstrated at Four Corners.

The seed banks in some of the post-mining wetlands do not appear to be different in size and species composition from the natural marshes sampled in this study. However, the actual vegetation present is not always as diverse, dense, or well developed, except in cases where muck (topsoil) from a donor wetland was applied. As an example, the results of lineintercept transects in mucked and unmucked areas of the marsh at Fort Green showed that the mucked areas to have 100 percent cover, while the unmucked areas had less than 30 percent cover.








72

Marsh Transect Study


Water levels and hydroperiod. Daily water levels in the Fort Green wetland were summarized as mean monthly values for the period of the study, August 1982 to December 1985 (Figure 11). Evident trends include the typical annual hydroperiod cycle and the drought that began in late-1984 and continued through late summer of 1985.

The typical annual hydroperiod cycle began with low water in early winter followed by a rise in late winter or early spring and a spring peak. The cycle continued with a summer decline, a late summer peak, and a fall decline. With the exception of the 1985 drought cycle, the annual hydroperiod in the basin has typically varied about 0.3 m between lows of approximately 36.42 m msl to peaks of about 36.67 m msl.

From the fall of 1984 through the spring 1985 a drought occurred that was unrelieved by spring rains. Water levels in the basin declined steadily from August 1984 to June 1985, when they reached a monthly low of 35.37 m msl. The late summer rains of 1985 brought the water level up to the typical late summer peak by August.

The transect elevation data were used to generate individual transect profiles (see Figures 12 and 13). Four of the transects (97, 115, 125, and 130) began at elevations between 36.06 and 36.27 m, while transect 105 started at a lower elevation (35.60 m msl) and transect 139 started at a
















36.5



















A S O N D J F M AM J J A S O N D J F MA M J A S O N D J F M A M J J A S O N D
1982 1983 1984 1985 Month



Figure 11. Hydrograph of surface water elevation in Fort Green wetland based on average monthly values for the period August 1982 through December 1985.
I.)









74










Muck Treatment Zone




37.0



TRANSECT 97








35.5 - Treatment:.
0 30 60 90 120 150 180 Trnw Dbnce (m) 37.0











139 with muck treatment zones indicated.
36-0




0 30 60 90 120 150 180 Tmtw Dblen (m) 37.0











TRANSECT 139

0 30 60 90 120 150 180 Tmwo" Dkbrm (m)





Figure 12. Elevation profiles of marsh transects 97, 105 and 139 with muck treatment zones indicated.








75














TRANSECT 115

0 30 (0 90 120 150 180 Truma Dilmbo (m)
37.0









TRANSECT 125
35.5
0 30 60 90 120 150 18 37.0



'





TRANSECT 130

0 30 e0 90 120 180 180 Trag Disnce (M)




Figure 13. Elevation profiles of marsh transects 115, 125, and 130.








76

higher elevation (36.45 m msl). Four of the transects ended at approximately the same elevation of 36.60 m msl. The remaining two transects (130 and 139) ended at approximately 36.80 m msl.

The daily basin water levels for the period August 1982 to December 1985 were used to generate a depth exceedance relationship (Figure 14) showing percent of the time a given elevation was inundated. The graph shows a 1.2 m variation in water level during the study period; elevations below 35.51 m msl were inundated 100 percent of the time and areas above 36.73 m msl were never inundated. The curve slopes gently in the 80 to 100 percent inundation, range which covers a relatively broad range of elevations from 35.51 to 36.33 m msl. The 70 to 80 percent inundation zone covers a relatively narrower elevation range (36.33 to 36.45 m msl). The slope of the depth exceedance curve is fairly steep in the 0 to 70 percent inundation range (elevation 36.33 to 36.73 m msl) then flattens at the maximum inundation of 36.73 m msl.


Emergent Macrophytes. The changes in cover of pickerelweed (Pontederia cordata) and cattail (Tvpha latifolia and T. domingensis) on each of the six transects through each of the eight sampling periods were summarized from the lineintercept data. Pickerelweed and cattail were used because each was initially the dominant perennial emergent macrophyte in the mucked and unmucked zones, respectively. This










100

90 80 70


60

50

4030 2010

0 -1..I _ LL1 1 I 1.L1 IL
35.5 36.0 36.5 37.0
ElevaUtion (m mal)




Figure 14. Depth exceedance curve for Fort Green wetland indicating the percent inundation for each elevation over the time period August 1982 through December 1985.








78
dominance was consistent throughout the study (see detailed vegetation data in Appendix B).

The time series of cover changes for the two taxa (Figures 15a through 15f) illustrate several aspects of the biology of the two species and differences in the marsh community development in mucked and unmucked areas. Pickerelweed became well established in the mucked zones of transects 97 and 105, but failed to reach the same level of development on any of the other four transects, including mucked transect 139. Conversely, cattail became well established on the overburden transects but lagged in colonizing those areas with well established stands of pickerelweed (transects 97 and 105).

Also, through the first few sampling periods, the sequence of stand establishment is evident for both taxa:

(1) initial establishment of individual plants or clumps, (2) expansion of initial clumps, and (3) consolidation of clumps into larger patches or stands. Following the consolidation phase, most of the large clumps remained stable up to the drought of 1985. After the establishment phase, some movement and adjustment to other areas of the transect took place, especially in the case of cattail. This sequence of establishment is well demonstrated on transects 97 and 105 for pickerelweed (Figures 15a and 15b) and transects 115, 125, 130, and 139 for cattail (Figures 15c, 15d, 15e, and 15f). One particular difference between the two taxa is the vagility

























Figure 15. Percent cover by Pontederia cordata and TvPha latifolia on marsh transects at Fort Green in fall 1982; spring, summer, and fall 1983; spring, summer and fall 1984; and summer 1985 at (a) transect 97, (b) transect 105, (c) transect 139, (d) transect 115, (e)transect 125, and (f) transect 130.





O

Wt
(i) PSus.L (mu) .o( uq n,,,L091 Wf I (El (3 09 m 0 ( (31 (el (3 09 oG 0






loo?2
I~ t ' J' rPL-~~I[I






1 11'14 llUU pa I 2 U
iIi I 'iii 1? 1L Pud

[iNIi llIl' 1 T !!1I iobcO O 6i, I -*


I If j
liU ' 1 NII I I 0,,-,

L~P U~C tpuul
M L9 l~L~s PMUNAL
[iF wolI AL I FflUJW] cmiRo


















9'
ml *1~ 9'
~ I I

I I'M
Cover (%) Cow (%) Cow (%) Cow (%) Cow (%)
~c ~a Be jo Cover (%) Cow (%) Cow (%) �~ ~ ~e S



S

[A





4- I' i


EL~E


0 U,

S

[A


















LB










(w) OUgo e iwj (w) soqeo sm
a st S as o o0 6 S a , o 0 t o a0 munts










a Ja


t l'1r [_ ________t___'im 1 ..i ' 0 �




ETI [flF ___ll_ "-L I II I [ IV.


ac P =l s a miw - - "







(m) oLsl pemmulj (w) *oueIIUO PIeMuI
06 SL 9)% 0 06 L o oc St 0
SL i o r uu

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r'Tr l"1I T r U 0 MU Oun


UIII] liJ'iUL ' I i __I_' _ lo PA_-ao





agospg 1 agIpm a sspu
l 1II LI lli] f__l 7 II L ,-,'III 94 pIVlI
I=MP= 8PP~911 qSuod







(W) sqo a iosMJus (u) utIoseu s-L
Oct 901 0 W 00 910 oc 9t 0 01 t 0 9L 09 9p o st 0








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S'001
o



I I I _ _ _ _ _ _ _ _ I 06 00 21 P c0 0 p 004







eggagg legm se gJooa


[H II1 cu 1-I t
ue~~I~s~y. I isuw

I F I lo ant od








86

of the propagules. Cattail has a very small, wind-dispersed seed; pickerelweed has a heavier, water/animal-dispersed fruit. On several of the transects, cattail was able to colonize new areas as they became available with the falling water levels of the drought of 1985. Cattail appeared more successful at expanding into open habitat than pickerelweed, but other taxa were equally opportunistic, especially bulrush (Scirpus californicus) and dogfennel (Eupatorium capillifolium).

Major changes in the littoral zone vegetation resulted from the drought. The overall species richness and total cover values within the wetland were within the range found in previous periods, but the manner in which the cover was apportioned over the various taxa was significantly different. For both the topsoiled and overburden areas, the cover of many common species declined and dramatic increases in cover were shown by other taxa, especially dogfennel and bulrush.

Dogfennel increased profoundly in cover percentages (25 percent and 18 percent for muck treatment and overburden areas respectively) (Table 7), especially in the deeper areas of the wetland as the water levels receded. At the peak of the drought, most of the area that typically had standing water was vegetated with a well established, monospecific stand of dogfennel by April of 1985. The timing of the dogfennel germination means that the seeds would have had to have been lying dormant in the substrate; as the water level receded,





I I I M









87

Table 7. Percent cover of Rupatorium caDillifollium and Scirous californicus on suck treatment and overburden transects, Fort Green marsh,eight sampling periods between fall 1982 and summer 1985.





Eu~atorigx canillifolina Sciruna californicu

Sampling Muck Overburden Muck Overburden
Period Transects Transects


Fall 1982 6 - - Spring 1983 0.2 -- -Summer 1983 0.4 0.1 -- Fall 1983 0.1 <0.1 - -Spring 1984 0.1 0.2 -- 0.2 Summer 1984 0.3 0.2 0.2 0.3 Fall 1984 1 0.3 0.9 0.9 Summer 1985 25 18 6 9








88

the dogfennel seedbank responded and a complete cover developed.

Bulrush also increased in cover at the north end of the basin, as seen in 1985 results from transects 125, 130, and 139. As with dogfennel, the increase occurred in normally flooded areas lacking established emergent vegetation. The area of bulrush invasion was also a site of noticeable invasion by Saqittaria lancifolia and dogfennel. These areas showed little to no invasion by cattail, which was well established in the vicinity and had been spreading vegetatively for the previous two seasons. Bulrush was able to colonize and establish in an area that appeared to be ideal for cattail invasion.

The transect specific elevation profiles and inundation frequencies were used to compare the zones of establishment of cattail and pickerelweed (Table 8). The two taxa do occupy roughly the same zone within the wetland based on the patch establishment (Figures 15a through 15f), from approximately elevation 36.33 to 36.58 m msl and with an inundation range of 40 to 80 percent. The results from transect 105 are particularly interesting because the mulch was spread in deeper areas, down to elevation 35.51 m msl, that were permanently flooded. These deepwater stands were neither invaded nor encroached upon by cattail during the study period. They were also not ephemeral in nature, remaining constant throughout the study although they showing similar









Table 8. Summary of transect distance, elevation range, and inundation frequency of
establishment zones for Pontederia cordata and Typha sp. on marsh transects at Fort Green wetland reclamation demonstration project; and summary of transect distance, elevation range, and inundation frequency of muck treatment
zones on transects 97, 105, and 139.





luck Troateat Trassects Ovrhbrde Soil Transects

o7 10 139 115 125 130 Pontederia cordata

Initial Appearance distancee a) So to IS I to 104 67 to 7 52 1 62 225 12 Istablishl ut loes (distas co ) so to IS10 to 184 T7 to 81 21 to 64 225 i 31 12
location lune (a ul) 36.11 to 36.33 35.58 to 36.39 36.5 to 36. 8 36.36 to 36.45 36.4 A 36.51 36.41
lasedation fre cl ecy to 865 I to f160 I to 35 1 to 7SI 6 to 75 T151

Typha up.

Initial Appearance (distance a) 115 to Ill 75 to II TO i t0 45 to Is TS to21 SI to 5 lstablishnet le (dista ee a) I to 125 I6 to Ill to II 32 to 65 I4 to 122 8 to 62
Ilevati laqo (a asl) 36.27 to 36.36 36.36 to 36.42 36.46 to 36.56 36.40 to 36.60 36.36 to 36.51 3).30,to 36.5
laudatlon i re teIl SM 1t to Il$ 4s to 76 6 to 1T6 4t to Ut 56 to Is

lack Treatent Area

Treuteot one (distance a) 6I to III 5 to 115 to I ----------- ----------- ----------Elevation luae (a al) 36.1l to 36.45 35.66 to 36.31 36.45 to 36.85 ----------- ----------- ----------Inadation Ireancy Ts to 865I t to 1t A to T ----------- ----------- ----------toD








90

drought response. This indicates that macrophytes like pickerelweed can become established in deep water areas and muck application should be extended down to elevations with an average depth of flooding of up to 1 m or more.

Large stands of pickerelweed developed only in the muck treatment areas. Though it produced large numbers of seeds, pickerelweed did not spread far from the areas of initial establishment during the first four growing seasons.

Upland Succession Plots


Seed Germination and Survival


The experiment was originally designed as a nested analysis of variance with a balanced design (i.e., equal replications for each treatment). A sampling mistake during the second weeding event (May) changed this plan, when plot 15 was weeded instead of plot 18. The error was not discovered until the third weeding (June), at which time it was decided to continue weeding plot 15. This change created some difficulties as to the treatment status of plots 15 and 18. To incorporate plots 15 and 18 into the analysis, the analysis of variance (ANOVA) for each species was carried out using two different assignments for the plots: one analysis with plot 15 assigned to weeded treatment and plot 18 dropped and a second analysis with both plots dropped. Analyzing the data following the original plot assignments (15 to enhanced








91

colonizer and 18 to weeded) was clearly inappropriate, as plot 15 could be no longer be considered as part of the enhanced colonizer treatment after it was weeded, but a simpler solution seemed to be to drop plots 15 and 18 from the statistical analysis altogether. Although an unbalanced design may result, any problems of equivocation over the treatment status of plots 15 and 18 are eliminated. An ANOVA configuration in which plot 15 is assigned to the weeded treatment and plot 18 is dropped is also a fairly clearcut case. As plot 15 was weeded during the later part of the growing season, the seedlings were growing under weeded conditions beyond the germination stage.

The seed plots yielded information on germination, the survival of the germinating seeds, and the growth of the surviving seedlings. Total germination was estimated with data from the two sampling periods in March and October 1984 (Table 9). Because the location of each seedling in the plot was recorded at the time of sampling, the fate of any given seedling could be followed through time. Thus, the mortality of germinating seedlings could be estimated and an idea developed of the phenology of germination (Table 10 and Figure 16).

Overall, 20 percent of the seeds planted did germinate and percent of those germlings survived through the first growing season. The individual species showed a full range of response in both germination and survival. Magnolia was









Table 9. Seed germination in Gardinier seed plots as measured by seedling counts in
March and October 1984 along with the total cumulative germination. Data
given by species and treatment.





Caltia laevimata L idihar straifla Caria labra Sahal ualaatto Dearcs lanolia randiflora Total
Tut.et hClaiEtin Cumlative Ceolatin Cuulatin Calatie Calelatti Caselaltin
and plot arch Oct Total larc Oct Total larch Oct Total arch Oct Total larc Oct Total arck Oct to arhOt Total

5 12 3 3 623 23 T 12 ft
3 1 3 1 2 47 8 1 1 28


Cololsed 2 5 2 1 5 1 44 1 1 32 15
1 i I 3 3 1 3 I 22 I II 3 1 8 451 I6
3 21 I II 1 2 23 4 48 I 1 I 2 2

Leeded
3 6 7 2 1 2 3 � 6 13 41 5 I 1 0 22 51 6
S4 4 0 t 10 I 41 I I 1 " 28 I 11
1 13 13 13 1 42 48 I 1 0 216 2
S I ii 1 I 1 1 1 1 I I f. I1 I1 t It if 1?
31 21 36I 11 5 14 1 21 23 1 4 41 66 111 1$ $ I I 111 246 2)3


4 1 I 1 2 1 3 1 3 4 5 5 1 5 42 0 I 2 6 44 il 1 5 11 1 1 1 4 4 5 7 1 II 4 4 I I 21 5It 11I 1 1 6 12 0 I I 5 6 3 3 11 I42 41 5 S 1 11 56 I 12 IL 2 14 3 I 3 3 1. 4 I I II 4 I51 I I 1 41 51 If
3U I1 44 5 1 I 6 13 i 1 23 23 11 166 111 S 0 111 211 I21
135 47 154 31 Is 45 32 61 SI S 1t5 115 217 4It 131 i 0 491 69 1125






ha




Full Text
190
Rogers, L. E., and R. J. Lavingne. 1974. Environmental
effects of western harvester ants on the shortgrass plains
ecosystem. Env. Entomol. 3:994-997.
Rushton, B. T. 1983. Examples of natural wetland succession
as a reclamation alternative. In D. J. Robertson (ed.),
Symposium on Reclamation and the Phosphate Industry.
Florida Institute of Phosphate Research, Bartow, Florida.
. 1988. Wetland reclamation by accelerating
succession. Ph.D. Dissertation. University of Florida,
Gainesville.
Salem, M. Z., and F. D. Hole. 1968. Ant (Formica exsectoides)
pedoturbation in a forested soil. Soil Sci. Soc. Amer.
Proc. 32:563-567.
Salt, G. W. 1979. A comment on the term emergent properties.
Amer Nat. 11:13-18.
Schnoes, R. S., and S. R. Humphrey. 1987. Terrestrial plant
and wildlife communities on phosphate-mined lands in
central Florida. Bulletin of the Florida State Museum
30:53-116.
Shrikhande, J. G., and A. N. Pathak. 1948. Earthworms and
insects in relation to soil fertility. Curr. Sci. 17:327-
328.
Shuey, A. G., and L. J. Swanson, Jr. 1979. Creation of
freshwater marshes in west-central Florida. In D. P. Cole
(ed.), Sixth Annual Conference: Restoration and Creation
of Wetlands. Hillsborough Community College, Tampa,
Florida.
Smith, R. L. 1980. Ecology and Field Biology. Harper & Row
Publishers, New York. 835 pp.
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direct-seeding of tree species on surface mines spoil after
years. In D. H. Graves, and R. W. DeVore (eds.),
Proceedings of 1983 symposium on Surface Mining, Hydrology,
Sedimentology, and Reclamation. University of Kentucky,
Lexington, Kentucky.
Thorpe, J. 1949. Effect of certain animals that live in
soils. Sci. Monthly. 68:180-191.
Tourney, J. W. and C. F. Korstian. 1942. Seeding and planting
in the practice of forestry. John Wiley and Sons, New
York.


65
occurrence of the species divided by the sum of all species
frequencies. Both relative density and frequency were
connected. With this type of calculation, both relative
frequency and relative density are constrained to values
between 0 and 100 percent, which produces an importance value
for each species in the range 0 to 200.
The most striking aspect of the calculations was the
numerical dominance of soft rush (Juncus effusus), which
accounted for 84 percent of the germinating seeds in the
study. It was also the only species found in all samples,
yielding an absolute frequency of 1.0.
The 20 species of highest importance value account for
92.5 percent of the total importance value (see Table 6). In
fact, the four species of highest importance value soft rush,
smartweed (Polygonum punctatum), Cvoerus rotundus. and
Ludwiaia virqata account for 94 percent of the relative
density and 66 percent of the total importance value. These
four species can be considered the dominant species in this
study and serve in general to characterize the seed banks
sampled from central Florida.
Floristic similarity. Floristic similarity of seed bank
samples was measured using the similarity index of Czekanowski
for binary data. The index is defined as follows:
Czekanowski's index = 2a/(2a + b + c)
where a = species common to sites 1 and 2, b = species found
at site 1 but absent at site 2, and c = species found at site


121
rates were 5, 17, and 120 times higher than rates on the
adjacent non-mound soils for tests 1, 2, and 3, respectively.
Mound soils had infiltration rates of 0.1 to 6.0 cm/min versus
0.02 to 0.05 for the non-mound soils.


192
Webster, J. R., J. B. Wade, and B. C. Patten. 1974. Nutrient
cycling and the stability of ecosystems, pp 1-27 In F.G.
Howell, J. B. Gentry, and M. H. Smith (eds.), Mineral
Cycling in Southeastern Ecosystems. CONF-740513. NTIS,
Springfield, Virginia.
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Minnesota Press, Minneapolis, Minnesota. 146pp.
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in vegetation. Bot. Rev. 45:229-299.
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Ecol Monog 23:41-78.
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1976. Biosynthetic alteration in a British Columbia soil
by ants (Formica fusca Linne). Soil Sci. Soc. Amer. Proc.
40:422-426.
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Communities. Benjamin Cummings, Menlo Park, California.
186 pp.
Wilson, N. L. J. H. Collier, and G. P. Markin. 1971.
Foraging territories of imported fire ants. Ann. Entomol.
Soc. Amer. 64:660-665.
Witkamp, M. 1971. Soils as components of ecosystems. Ann.
Rev. Ecol. Syst. 2:85-110.
Wolf, R. W. 1986. Seed dispersal and wetland restoration.
M.S. Thesis. University of Florida, Gainesville.
Zellars-Williams and Conservation Consultants. 1980.
Evaluation of pre-July 1, 1975 disturbed phosphate lands.
Florida Department of Natural Resources, Tallahassee,
Florida. 107pp.
Zimmerman, D. M. and J. L. VanKat. 1984. Effects of species
removals on an old field community: A five-year examination
of successional mechanisms. Bull. Ecol. Soc. Am.
65(2):65.


2
species but provides a rich environment for testing paradigms
describing the pattern and process of succession. Detailed
ecological studies of the recovery process on mined lands may
also identify some solutions to existing reclamation problems.
The succession and human-managed reclamation of phosphate-
mined lands in central Florida provides and opportunity to
evaluate successional theory and use the knowledge to
facilitate reclamation. This dissertation examines
successional processes on phosphate-mined lands, especially
marsh development, upland forest development, and the roles
played by seed banks and mound-building ants.
In a few cases an understanding of wetland succession has
been translated into a successful technique for wetland
creation and restoration. In the Tampa Bay area it was
observed that formerly unvegetated intertidal areas were
quickly colonized and stabilized by smooth cordgrass (Spartina
alterniflora) which presumeably helped mangrove seedlings to
become established years later (Lewis 1982). In 15 to 20
years the mangroves eventually shaded out the cordgrass and
became dominant. Lewis developed a technique for establishing
a nurse crop of cordgrass which has since become a common
practice for mangrove establishment.
Previous Studies of Succession on Mined Lands
Many studies of unreclaimed mined lands have documented
the paucity of late successional species on upland sites


177
self-organizing choices. It is believed that diversity
stabilizes many ecosystem during environmental fluctuations
or other periods of potential stress, buffering the system by
providing more self-organizational choices, that extend the
range of environments in which community structure and
processes, such as energy flow, can be maintained.
Seed/propagule banks and accumulated below-ground
structures (e.g., roots, rhizomes) provide a storage of
"choices" for all environmental contingencies, providing some
support for the self-organization paradigm. In wetland and
upland communities, seed banks provide a mechanism for rapid
recovery from catastrophic mortality resulting from fire,
clear-cutting, and drought. The rapid response of seed banks
to environmental change minimizes interruptions to the energy
flow in the community helping to maximize overall primary
production. A relatively continuous flow of energy through
an ecosystem, even during recovery periods, prevents an
uncoupling of the above-ground and below-ground components,
since many rhizosphere processes depend upon energy inputs
from the above-ground community.
It appears that many mature, self-maintaining wetland and
upland systems contain a sufficient number of "choices" to
meet a variety of environmental contingencies. Duplicating,
or mimicking the "choices" found in many natural ecosystems
by incorporating diversity into reclamation may prove to be
a valuable design principle for creating self-maintaining


Figure 4. Causal loop diagram showing feedback relationships between mound-building
ants, plants, other consumers, water infiltration, soil development and nutrient cycle.
u>
to


and
self-
floristics, relay floristics,
organization models.
coevolution,
viii


129
and create patch disturbances of varying size within the
wetland. The affected areas are typically disturbed down to
the subsoil, with all vegetation removed. The hog activity
observed during the marsh study was generally restricted to
the wetland/upland transition zone. Bersok (1986) found the
impact of the foraging hogs in this marsh was limited to
monospecific stands of cattail, and patches opened by hogs
were recolonized by vegetative expansion of the surrounding
cattail plants. This type of disturbance may be similar,
although less extensive, to the muskrat "eatouts" described
by van der Valk and Davis (1976) and Weller (1981) in marshes
in the midwest. The effect is to create a shifting mosaic of
open areas available for colonization.
Effect of Hvdroperiod and Drought. The hydroperiod factors
of depth, duration and seasonal pattern of flooding have a
broader impact than hog activity on the marsh. The water
level fluctuations provide a seasonal dynamic. Of more
importance though are the events with periods longer than a
year, such as the regional drought cycle that occurred from
fall 1984 through summer 1985.
As the drought cycle is a natural part of the climatic
regime, it is one to which a wetland must be adapted. The
reaction to the 1984-85 drought showed that the marsh had
developed a mechanism to respond to environmental change.
Drought conditions exposed previously flooded but unvegetated


DISCUSSION
Marsh Development
Seed Bank Formation
The formation of a seed bank appears to be a relatively
rapid process, beginning almost immediately after the land
surface has been exposed. Seed bank samples from all but the
youngest mine sites fall within or just below the range of
seed density and species diversity found in natural wetlands
in Florida, Iowa, and New Jersey.
The species present in the seed bank samples are largely
the wetland ruderal species characteristic of environments
subject to disturbances such as water level fluctuations.
They are the initial colonizing species, the annuals and
short-lived perennials of exposed mudflats, wetland transition
zones, and shallow littoral zones. Notably absent are the
late successional marsh species: the emergent macrophytes,
submergent macrophytes, and free-floating aquatic species.
A possible reason is the germination conditions used in the
seed bank tests, which were similar to those of an exposed
mudflat, but the absence of the seeds of the late successional
species from the samples is a more likely cause. The seeds
124


53
freezes occurred before any possible treatment effects could
have been exerted, all of the freeze-killed seedlings were
replanted on March 27, 1984, which was then used as the
starting date for growth measurements on the seedling plots.
The plots were measured again in September 1984. At the time
of measurement, the height of each seedling and growth
condition were recorded.
Mound-building Ants and Upland Succession
Survey of Mound Density
Mound densities on the 1-year old IMC Tiger Bay site,
the 2-year old Agrico Fort Green site, and the 5-year old IMC
Clearsprings site were sampled. Replicate 5 m by 5 m plots
were semi-randomly located at each site, and the location,
diameter at base, height, general condition, and level of ant
activity of each mound within each plot were recorded.
Physical Soil Analyses
Bulk density. Bulk density of mound and non-mound soils
at the Fort Green Payne Creek site was sampled with a bulk
density core sampler. Seven mound and seven non-mound samples
were taken. The samples were oven dried at 103 C until a
constant weight was attained, and the density was determined
based on the volume of the sampler and its oven-dried weight.


176
derived. Further study and analysis will be required to make
that determination, as the issue was not addressed in this
dissertation.
In addition to seed dispersal, animals serve many other
functions in the community such as pollination, nutrient
cycling, and substrate turnover. The fire ant study
demonstrated the beneficial effects of soil fauna on chemical
and physical properties of overburden soils. Recovery of
ecosystems after severe disturbance includes re-establishing
the below-ground community and processes, and coupling the
above-ground succession with the below-ground succession.
Reclamation activities should encourage the formation of a
diverse soil fauna. Factors likely to contribute to the
return of a rich soil fauna which can be easily incorporated
into a reclamation design include: (1) vegetation of high
species richness, (2) a high plant cover, and (3) a widespread
and thick litter layer over at least part of the area, and the
presence of some logs and standing dead wood. For example,
specific plantings can help with the first two items and
trees, topsoil, litter and woody debris from the pre-mining
land-clearing operations can be stockpiled and reused later
to create litter patches, brush-piles and downed logs.
Self-Organization
In the self-organization paradigm, the actual species
composition of the community is a function of the system's


161
animals. Although mound construction is localized, a larger
area affected is altered rapidly and extensively. Channelling
below the mound produces an extensive interconnected network
that penetrates the parent material. Deep channeling and
vertical transport of soil material lead to an alteration of
the soil.
Some of the changes may persist for some time after mound
abandonment. The channel system gradually collapses and the
mound slumps, but soil alterations and nutrient availability
may selectively favor certain plant species long after the
mound has been abandoned. Levan and Stone (1983) estimate
that pedoturbation by ants can be quite significant when
viewed over the long term. Assuming an average mound density
of 2,000/ha and an average mound basal area of 25 cm mounds
occupy approximately 5 percent of the landscape. If it can
be further assumed that the average life of a mound is
approximately 2 years (Lofgren et al., 1975), then all the
soil in a given area may be affected in 40 years time.
Infiltration. An increase in infiltration rates
beneficially alters the water balance of a developing
community by preventing the loss of that scarce commodity,
water. Water infiltration rates were higher in mound soils
than non-mound soils in all measurements. The most obvious
differences in the soil types were the pore space, texture,
and bulk density.


Figure 11. Hydrograph of surface water elevation in Fort Green wetland based on average
monthly values for the period August 1982 through December 1985.
-j
u


BAY SWAMP
FOUR CORNER MARSH
PASTURE MARSH
SANLAN JUNCUS
SANLAN EtCHHQflNtA
FOUR CORNERS MULCHED
FOUR CORNERS PLANTEO
FOUR CORNERS CONTROL
FOUR CORNERS SWAMP
CLEARSPRINGS SOUTH BASIN I
CLEARSPRINGS SOUTH BASIN 2
CLEARSPRINGS NORTH BASIN '
FORT GREEN MULCHED VEGET
FORT GREEN MULCHED UNVEGET
PERCENT
FLORISTIC SIMILARITY
80-100 high
60 79 mod high
40-59 moderle
20 59 mod low
0 19 low
o\
o


Fail 1982
Spring 1963
Summer 1963
Fall 1963
Spring 1964
£,ooin
U
too n
100
Summer 1964 $
J
Fall 1964
Summer 1985
100
Pontederia cordata
Traneect 105
4L
1
n
-L-rLj-V-
100
J.
*! 1
JZ
11
15 30 45 60 75 SO 106 120
Traneect Distance (m)
0
Typha latttolla
Transect 105

, T ,
r.zL
i ~i r I I | |
30 45 60 75 80 105 120
Transect Distance (m)
o
15


TABLE OF CONTENTS
ACKNOWLEDGMENTS
ABSTRACT vi
INTRODUCTION 1
Previous Studies of Succession on Mined Land 2
Background and Concepts 3
Succession Theory 3
Wetland Succession 9
Role of Consumers 13
Competing Paradigms of Succession 20
Initial Floristics 20
Inhibition 20
Relay Floristics 24
Coevolution 24
Self-organization 24
Changes in Paradigms 24
Hypotheses and Objectives 27
Marsh Development 28
Upland Forest Development 29
Mound-building Ants and Ecosystem Development 30
Description of Study Sites 33
METHODS 43
Marsh Development 43
Seed Bank Survey 43
Marsh Transect Study 45
Upland Forest Studies 47
Direct-seeded Plots 50
Seedling Transplant Plots 51
Mound-building Ants and Upland Succession 53
Survey of Mound Density 53
Physical Soil Analyses 53
Chemical Soil Analyses 55
Plant Growth Study 57
Statistical Analysis 58
IV


57
Plant Growth Study
Several greenhouse experiments were set up to evaluate
a potential growth difference between plants grown on mound
and non-mound soils. The tests used a common early
colonizing grass, vaseygrass (Pasoalum urvillei), and a woody
plant, sweetgum (Liouidambar stvraciflua), as the assay
organisms.
The composite soil samples, as described above, were used
in the growth experiments. Ten plastic seedling tubes were
filled from each of the six composite samples ten plastic.
In each group of ten seedling tubes, five received a seedling
of vasey grass and five received sweetgum. The tubes were
placed in a greenhouse.
At the end of 60 days, the seedlings were harvested and
dried at 103 C to a constant weight. Each vasey grass
seedling was subsequently divided into above- and belowground
portions that were weighed separately. The sweetgum seedlings
were divided into root, stem, and leaf components, each of
which was weighed separately. Leaf area of each sweetgum
seedling was determined by making a xerographic image of the
leaves, cutting out the individual images, and measuring leaf
area with an automatic area meter.


149
addressing the pattern and process of ecosystem development
becomes inextricably more complicated. However, the very low
levels of germination/survival of sweetgum in the seed plots
caution against giving strong support to the results.
Like sweetgum, cabbage palm also showed an opposite
response to treatment effects from the seed and transplant
plots. The seed plot data favored the acceptance of the
initial floristics model, while the transplant plot results
were not clearly weighed toward either the inhibition or relay
floristics models.
The two experiments can be seen to address the same
fundamental issues of earliest succession at two succeeding
stages of development. The direct-seeded plots simulated the
critical period during the first growing season after
propagules arrive at an open, uncolonized landscape. The
proper cues must be made for germination, establishment
depends on a suitable microenvironment, and adequate resources
must be continually available for survival. The transplant
plots mimicked the second growing season, the next stage in
woody plant life, which is less precarious than germination
and establishment but still heavily dependent on the quality
of the microenvironment. The results of the experiments are
strikingly similar for these two stages; in no case was
germination or growth (as measured by height change) enhanced
or increased by the presence of the natural or enhanced
colonizer treatments. The results appear to offer strong


78
dominance was consistent throughout the study (see detailed
vegetation data in Appendix B).
The time series of cover changes for the two taxa
(Figures 15a through 15f) illustrate several aspects of the
biology of the two species and differences in the marsh
community development in mucked and unmucked areas.
Pickerelweed became well established in the mucked zones of
transects 97 and 105, but failed to reach the same level of
development on any of the other four transects, including
mucked transect 139. Conversely, cattail became well
established on the overburden transects but lagged in
colonizing those areas with well established stands of
pickerelweed (transects 97 and 105).
Also, through the first few sampling periods, the
sequence of stand establishment is evident for both taxa:
(1) initial establishment of individual plants or clumps, (2)
expansion of initial clumps, and (3) consolidation of clumps
into larger patches or stands. Following the consolidation
phase, most of the large clumps remained stable up to the
drought of 1985. After the establishment phase, some movement
and adjustment to other areas of the transect took place,
especially in the case of cattail. This sequence of
establishment is well demonstrated on transects 97 and 105 for
pickerelweed (Figures 15a and 15b) and transects 115, 125,
130, and 139 for cattail (Figures 15c, 15d, 15e, and 15f) .
One particular difference between the two taxa is the vagility




Environmental
i Conditions J
Figure 2. An energy circuit diagram of a Gleasonian model of wetland succession
(redrawn from Van der Valk 1981).


4
the control of the regional climate. He held that in
succession, the community repeated a sequence of stages,
similar to the development of an individual organism from
birth through death, that was an orderly directional process
predictable in its development. As succession proceeded, the
community increasingly controlled its own environment and,
barring disturbance, became a self-perpetuating climax.
Succession occurred as waves of plant populations made
conditions suitable, or "prepared the way," for the next wave
and often to the detriment of their own continued survival.
To other ecologists of the time, the plant community was
less well defined and succession less orderly, directional,
and predictable than Clements suggested. Alternative concepts
of succession voiced by Gleason (1917, 1926, 1939) advocated
an individualistic, population-based approach in which the
plant association is seen as a coincidence rather than an
interdependent entity. The distribution of a particular
species in the landscape depends on its migration
characteristics and environmental requirements, and the plant
community is an artifact solely dependent on the grouping of
species with overlapping environmental requirements. Given
sufficient time, all species had equal access to all sites,
but species were found only on those sites with the
appropriate environmental conditions. According to this
allogenic theory, a particular species grows in the company
of any other species with similar requirements and eventually


30
vegetation. In both the enhanced colonization and enhanced
legume treatments, the natural colonization process was also
allowed to occur. Criteria for accepting or rejecting the
competing paradigms are given below.
1. If seedlings grew better with either the enhanced
colonization, natural colonization or legume treatments,
then the initial floristics and inhibition paradigms were
rejected in favor of the relay floristics paradigms.
2. If seedlings grew better in weeded plots, then the
initial floristics and relay floristics paradigm were
rejected in favor of the inhibition model.
3. If seedlings grew about the same in the weeded plot as
in other treatment plots, then the relay floristics and
inhibition paradigms were rejected in favor of the
initial floristics.
Mound-Building Ants and Ecosystem Development
Early successional mined lands provide an opportunity to
investigate interactions between species as the community is
developing in a simple system with a few producers and a few
consumers. Three field observations aroused interest in the
role and effects of mound-building ants in such a system.
First, fire ants (Solenoosis invicta) are one of the
earliest arriving invertebrate consumers on young strip-mined
lands. In central Florida, fire ant populations were usually
well established in the first year after mining ceased.
Second, herbaceous plants, especially grasses, growing
on ant mounds were typically more robust, with a richer green
color than plants found on adjacent non-mound soil. This


7
organization develops new programs for succession with which
species prevail that are reinforced by controls and material
cycles of the next larger system. This view has maximum
power as a self-design principle, in that there is survival
of those combinations of components that contribute most to
the collective power of the system. Species combinations are
reinforced that divide up and optimize the use of resources
to collectively maximize productivity, and species
substitutions occur through time as new choices are offered
and selected. Some Darwinian selfish selection is involved
but is regarded as secondary. Emphasis is on selection of
relationships that make the system perform, with evolution
ultimately occurring but on a longer time interval.
Modern proponents of the Gleasonian individualistic view
(McCormick, 1968; Drury and Nisbet, 1971, 1973; Horn 1971,
1974, 1975; Pickett, 1976; Connell and Slatyer, 1977) find the
classical Clementsian paradigm and its modern incarnation, the
holistic-ecosystem representation, unpalatable. McIntosh
(1982) points out that the studies by these researchers share
at least three characteristics:
1. They are commonly cited in recent discussion of
succession as providing "new" insights for successional
theory.
2. They are explicitly critical of Clements' holistic,
organism theory of succession and of what they interpret
as the successional theory of the organismic, holistic,
ecosystem ecology expressed by ecosystem ecologists.
3. The alternative models of succession proposed advocate
an individualistic, population-based approach emphasizing
life history attributes of organisms and the consequence


97
Another way of analyzing the seed germination and
survival data is to compare at the end of season survivors as
a proportion of the seeds planted. The data on seedling
survival from the experimental plots were converted to
percentages for analysis. It is known from statistical theory
that proportions or percentages have binomial rather than
normal distributions, and that the deviation from normality
is greatest for small and large values. The data can be
transformed, however, to obtain a distribution that
approximates normal. The square root of each percentage was
transformed to its arcsine to give an underlying distribution
that is nearly normal. The percentages were so transformed
(Table 11) before conducting the ANOVA.
For the case where the data are summed over species
within each plot the results of two ANOVAs are similar (Table
11a) When data from plots 15 and 18 are neglected in the
analysis, the means for the weeded, natural colonizer, and
enhanced legume treatments are not significantly different,
but the enhanced colonizer treatment mean is lower and
significantly different from the other three. When plot 18
is dropped and plot 15 is assigned to the weeded treatment the
result is essentially the same.
The plot-by-plot survival results can also be examined
for individual species. The analysis assumes that there are
no interactions between species. Because this assumption
cannot be made for multi-species seed mixes any inferences


100
Table 11c. Sugarberry (Celtis laevigata).
Treatment Means
Plot Assignments
PR>F
Weeded
Natural
Enhanced
for ANOVA
(ANOVA)
Legume
Colonizers
Plots 15 & 18
17.693
8.892
12.420
5.847
Neglected
.0772
A
A
A
B
B
B
Plot 15 Weeded,
18.387
8.892
12.420
5.847
18 Neglected
.0297
A
A
B
B
B


52
Seedlings planted on 1m centers
C Cabbage Palm
S Sweetgum
L Live Oak
Figure 9. Schematic for planting in Gardinier seedling plots.


Table 3. Mean number of germinating seeds per m2* by species for natural wetlands and
reclaimed and unreclaimed marshes in central Florida phosphate district.
four
¡¡Mill
lour Cortera
Clear Sorlaaa
fort Greet
Coraera
Bap
lateral
Paeture
JU£U'
Topad led
Planted
Control
Plaited
South
South
lortb
Topsoiled,
Topaoiled,
Saaap
la rah
larab
Polranaut
iichhoraii
larab
larab
larab
Saaap
Baa la 11 Baala 12
Baila
leietated
Oaieietated
Ooaulched
later aubulata
...
416
500
210
Bacckarli hiiiiiMii
...

...
...
...
...
...
...
...
125
42
292
...
...
...
Carer ap.
...
...
...
125
...
...
...

...
...
...
...
...
Croerua breilfollua
...
...
...
...
<16
...
...
...
...
11
...
...
...
...
...
Croeroa ap.
...
...
...
...
...
...
...
...
...
...
...
...
915
334
960
ClP4I1U rotnndua
ID
...
...
<16
3,750
166
...
...
500
1,666
4,125
1,500
...
...
...
Cmricrn 1
...
...
...
...
...
...
...
...
...
...
...
04
...
...
...
ItilllcHil aalterl
...
...
...
...
...
...
...
...
...
...
...
...
...
...
125
Idiota alba
...

...
125
...
...
...
...
...
250
541
42

...
...
loaatoriai cobpos1t1fo1iua
ID
...
511
...
...
125
16
125
250
375
...
42
14
fimhilini obtaalfollm
...
...
...
...
...
11
...
Graaaea, ookaoaa It
12
:::

12
...
...
...
...
...
125
42
...
...
...
...
...
...
13
ID
D2
...
...

...
...
61
...
...
250
125
...

15
IB
Ifdracntili rerticillata
...
12
11
...
...
...
...
...

1,625

...
...
---
...
D2
...
...
...
...
...
...
...
...
...
...
Iroerlcm autilna
D2
...
...
...
...
...
...
...
...
...
...
166
...
...
...
Jnacna effoana
292
67,211
11,132
51,625
7,625
32,750
31,116
1,500
10,625
1,675
1,916
1,160
209
42
1,210
Jiiacna bofoaloa
125
...
...
12
...
12
...
...
...
...
...
...
...
...
...
Idlilitil rlrrata
292

...
...
...
...
...
...
...
500
416
2,666
1,834
1,375
1,416
LudtitU taloatria
33D
...
...
...
...
...
...
...
...
42
...
...
...
...
...
Ladaliia leotocaroa
...
...
...
...
...
...
...
...
...
14
210
...
...
...
...
Polieoiut ouactatna
...
5,250
292
2,160
125
<2
126
...
<2
42
125
14

--
...
hlllltiat caolllaceut
...
...
...
...
...
...
...
...
...
42
1,042
04
...
...
Luti mhicillttm
...
...
...
...
...
...
...
...
...
<2
...
...
...

¡¡ililui parilfloma
251
...
...
...
...
...
...
...
...
...
...
<2
...
...
...
ScmhlUfllCtlt ?
...
...
...
...
...
...
...
...
...
42
...
...

...
...
Sltllull aedla
...
...
...
...
...
...
331
...
...
...
...
...
...
...
Oaktoat apeciea 11
...
...
...
...
...
...
...
...
...
375
1,134
2,750
375
...
...
12
...
...
...
...
...
...
14
250
42
...
...
...
...
...
IS
2,511
...

...
...
...
...
...
...
...
---
...
...
14
125
leaa 1 aeeda/a2
1,125
72,512
11,250
62,250
12,010
33,000
31,710
2,210
11,460
7,375
11,300
9,680
3,334
1,117
3,920
1 apeciea
11
3
1
6
5
1
4
4
7
16
13
14
4
5
6
ieiulU froi cor* eaaplea ID ci deep alth actual area aaapled corrected to ataadard refereace area of 1 i1.
Q\
O


11
in the vegetative cover of an area. In the van der Valk
model, succession occurs whenever a new species becomes
established or an existing one is extirpated.
The model is based on the life history characteristics
of the wetland species and the interaction of the species with
the prevailing environmental conditions (see Figure 1). Van
der Valk classified wetland plant species into 12 life history
strategies based on potential life span, propagule longevity,
and propagule establishment requirements. Under this scheme,
each life history type has its own unique set of
characteristics and associated responses to prevailing
environmental conditions, which act as a "sieve" in
determining the species composition of the wetland. As
environmental conditions change, so does the action of the
sieve and, therefore, the species present.
The van der Valk model focuses on the wetland seed bank
as the key biological component. The functional significance
of seed banks lies in providing the plant community with an
in situ means of regenerating from naturally occurring
disturbances (Grime, 1978). Van der Valk (1981) and van der
Valk and Davis (1976, 1978) have aptly documented and
demonstrated the role seed banks play in the vegetation
dynamics of prairie glacial marshes that undergo cyclic
patterns of flooding-drawdown-drought. In prairie glacial
marshes and other marsh systems (Keddy and Reznicek, 1982;


(a)


130
areas that were colonized subsequently and rapidly by a
variety of species. The timing of the drought and the species
composition on the exposed flats demonstrated that the source
of the colonizing species was the seed bank. The wetland had
developed its own seed bank, which is one of the principal
response mechanisms of wetlands to wide fluctuations in water
level.
Mature wetland systems respond to change with an in situ
mechanism that includes the seedbank as a major component.
In a short period, the Fort Green wetland has developed its
own seed bank. The muck applied in 1982 provided an instant
seed bank to certain areas, but the vegetation dynamics
highlighted during the drought occurred in areas where no muck
had been applied. Even on the muck treatment transects (97,
105, and 139) the rise of dogfennel and bulrush was confined
to those portions that had not received the muck treatment.
The establishment of bulrush and Saqittaria on drought-
exposed flats at the north end of the site is particularly
interesting, as the propagule source was undoubtedly from
within the wetland itself, and highlights the autogenic aspect
of community development in seedbank formation. Bulrush and
Saqittaria were planted; initially established plants spread
vegetatively, produced seed, and now act as seed sources for
further colonization. The formation of an internally
generated seed bank may be one indicator of ecosystem
maturity.


108
Table 12c. Sugarberry (Celtis laevigata).
Treatment Means
Plot Assignments PR>F
for ANOVA (ANOVA)
Weeded Natural Enhanced
Legume Colonizers
Plots 15 & 18
Neglected
NS
8.5 7.0
A A
6.5 8.0
A A
Plot 15 Weeded,
18 Neglected
NS
8.3 7.0
A A
6.5 8.0
A A


160
A reduction in bulk density may make the soil a better
rooting medium for established plants and possibly for
germinating seeds, as soil aggregates will be broken down.
Probably more important than absolute density differences is
the effect of breaking the surface crust. This may be
especially true on overburden soils, which tend to form very
hard surface crusts, because of a higher clay content than
native soils. Density changes are primarily a result of the
movement of individual soil particles or grains, which
increases pore space. Increased pore space can facilitate
gas exchange, evaporation, and water infiltration.
Mound building breaks up the crust aggregate, thereby
increasing the pore space in the surface horizon. Concomitant
with the surface effects of mound building is the creation of
an elaborate subsurface system of chambers and tunnels.
Tunnel systems extend as much as a meter or more below the
mound and lateral channels may extend outward from the mound
typically for a distance of several meters. The extensive
tunnel system creates an anastomosing network of
interconnected soil macropores that is maintained for the life
of the mound. Some of the soil profile alterations resulting
from ant activities may be lost temporarily during intense
rainfall, but the mound and tunnel system are guickly repaired
by the colony.
Nest construction may cause more rapid alteration of the
soil profile than would biogeochemical processes without


8
of natural selection as the essential basis of a modern
theory of succession.
Connell and Slatyer (1977) described three models by
which species may replace each other in a successional
sequence. They assumed no further changes in the abiotic
environment and that certain species usually appear first
because they have the ability to produce large numbers of
easily dispersed seeds, which are not adapted to germinating
and growing on occupied sites.
Model 1 assumes only certain early successional species
are able to colonize a site immediately after disturbance, as
in the "relay floristics" model of Egler and the classical
Clementsian view.
Models 2 and 3 assume that any arriving species may be
able to colonize, even those that typically appear late in
the sequence. These are alternative forms of Egler's "initial
floristics" model. In model 2, early colonists neither
increase nor reduce the rates of recruitment and growth of
later successional species. Species that "appear" later in
the successional sequence are those that arrived either
initially or later but grew very slowly. In Connell and
Slatyer's model of initial floristics, the sequence of species
is determined solely by life history characteristics. In
contrast, model 3 (termed inhibition) holds that once early
colonists secure the available space and resources, they
inhibit invasion by subsequent species and suppress the growth


CONCLUSIONS
The following points summarize the major conclusions relating
to the wetland and upland field studies and their implications
for reclamation and the paradigms of succession:
1. The application of muck from a donor wetland provides not
only a propagule bank of seeds and rhizomes but structure
in the form of the organic material itself and its
attendant microbial and microfaunal component.
2. The development of the seed bank within the wetland, as
seen by the spread of bulrush and Sagittaria.
demonstrates the workings of an autogenic process and
may provide one measure of community maturity. The
spread of bulrush and Sagittaria also indicates that
emergent macrophyte species other than cattail are
capable of invading open mineral soils in reclaimed
marshes.
3. The studies of wetland community development at Fort
Green show that the marsh communities resulting from the
muck treatment had a different species composition than
those arising by natural succession. These community
differences also proved to be stable for the first four
growing seasons.
179


Figure 1. General model of Gleasonian wetland succession
proposed by Van der Valk (Source: after Van der Valk 1981)


147
results as the analysis for all species summed. The vastly
greater number of oak seedlings masks the responses of the
other species, which, if examined separately or at least apart
from the oak data, lead to a much different conclusion.
The results of the height growth analysis for the other
four species are surprisingly uniform and contradictory to the
oak results. The ANOVAs for each show no significant
differences in mean seedling height among any of the four
treatment means, which supports rejection of the relay
floristics and inhibition models in favor of the initial
floristics model. This may indicate that individual species
do not show the same response.
In addition, the erosion problems encountered early in
the study provide support for the relay floristics model, by
showing that the early colonizing plants help stabilize soil.
Transplant plots. The transplant plot seedling growth
data can be considered to provide either clarity or more
confusion. Unlike the seed plot data, the transplant plots
did not have differing interpretations depending on whether
species were combined or treated separately. The result were
the same for three cases and barely dissimilar for the fourth
case. For sweetgum, oak, and all species combined only the
weeded treatment was shown to be significantly different and
it had the highest height growth. For cabbage palm, the mean
seedling growth in the weeded treatment was not clearly


148
superior but it was, along with the natural colonizer
treatment, significantly different from and higher than the
enhanced legume treatment mean.
Comparisons between seed and transplant plots. The
seedling height growth results from the seed and seedling
plots provide two views of the interaction between later-
arriving tree species and colonizing plants. Because the three
species used in the seedling transplant plots were also in the
seed plots, a valuable means of comparison was provided.
The oak seedlings exhibited the same height growth
response under experimental treatments in both the direct-
seeded and transplant plots. The increased height growth
under weeded conditions was common to both, as well as for
all species combined. These two cases provide some support
for the inhibition model, the oak bias in the seed plots must
be considered when all species are combined.
Sweetgum demonstrated an interesting contradiction in
response to treatments from the seed and transplant
experiments. Growth data from the seed plots favored the
initial floristics model, as none of the treatment means were
significantly different. In the transplant plots, however,
sweetgum growth was best in the weeded treatment, thus
favoring the inhibition model. The results indicate another
variable to consider; that is, that species may have different
life history stages that respond differently to early
colonizing species. If this is true, then the question of


54
Infiltration tests. Soil water infiltration differences
were measured at the Fort Green site using the paired
infiltrometer technique (Bertrand, 1965). A metal cylinder,
16.5 cm in diameter and filled with water, was used to measure
the rate of water intake of the soil. The metal cylinder was
placed on the ground and driven into the soil with a rubber
mallet to a depth of approximately 5 cm. A circular berm
approximately 10 cm high and 60 cm in diameter was then
created around the metal cylinder. The area enclosed by the
berm served as the outer cylinder. Both cylinders were
maintained at approximately constant head, or depth, by the
addition of water. The amount of water lost through the inner
cylinder over a measured time interval provided an estimate
of the infiltration rate. The inf iltrometer test was not
designed to measure absolute infiltration rates but rather as
a measure of relative infiltration rates in side-by-side
comparisons. Three such comparisons were made. The
first used three infiltrometers, with one placed over an ant
mound, one on an adjacent grassed area typical of the site,
and a third on a bluegreen algae flat. This test was run for
120 minutes. The second test, which lasted 60 minutes,
compared the rates of another ant mound and another "typical"
grassed area. The third test, which lasted 20 minutes, paired
another mound and "typical" grassed area.


183
Bertrand, A. R. 1965. Rate of water intake in the field. In
C.A. Black (ed.), Methods of Soil Analysis. American
Society of Agronomy, Madison, Wisconsin.
Best, G.R., and K. Erwin. 1984. Effects of hydroperiod on
survival and growth of tree seedlings in a phosphate
surface-mined reclaimed wetland. In 1984 Symposium on
Surface Mining, Hydrology, Sedimentology and Reclamation.
Univ. Of Kentucky, Lexington, Kentucky.
Bormann, F. H., and G. E. Likens. 1979. Pattern and Process
in a Forested Ecosystem. Springer Verlag, New York. 253
pp.
Bornemissza, G. F., and C. H. Williams. 1970. An effect of
dung beetle activity on plant yield. Pedobiologia
10:1-7.
Brown, B. J. 1982. The role of herbivory in high and low
diversity tropical agro-ecosystems. Ph.D. dissertation,
University of Florida, Gainesville.
Brown, J. H. 1973. Site factors and seeding methods affecting
germination and survival of tree species direct seeded or
surface-mined areas. West Virginia University Agriculture
Experimental Station Bulletin 620. 25 pp.
Bullock, S. H. 1974. Seed dispersal of Dendromecon by the
seed predator Poqonomvrex. Madrono 22:378-379.
Canfield, R. H. 1941. Application of the line interception
method in sampling range vegetation. J. Forestry 39:388-
394.
Chew, R. M. 1974. Consumers as regulators of ecosystems: an
alternative to energetics. Ohio J. Sci. 74:359-369.
Clements, F. E. 1916. Plant succession: An analysis of the
development of vegetation. Publication No. 242. Carnegie
Institution of Washington. Washington, D.C.
1920. Plant indicators: The Relation of
Plant Communities to Process and Practice. Publication No.
290. Carnegie Institution of Washington. Washington,
D.C.
Clewell, A. F. 1981. Vegetational restoration techniques on
reclaimed phosphate strip mines in Florida. J. Soc.
Wetland Sci. 1:158-170.


70
calculated using the Shannon-Weaver diversity index, given as
H' and defined as
H' = (Pi In P0
where P¡ is the ratio of the number of individuals of the ith
species divided by the total number of individuals in the
sample. The value of H1 is influenced by two factors: the
number of species, known as species richness, and the equit-
ability with which the individuals of the population are
apportioned among the species. The greater the species
richness or the equitability the greater the value of H'.
The overall range of H' values was 0.05 to 2.64; the
lower value was from the mulched, vegetated plot at Fort Green
and the highest from the Sacciolepis-zone at Lake Kanapaha.
The latter sample also had the highest seed density
(156,000/m2) and the highest species richness (38).
The samples with the greater number of species typically
had H1 values in the upper range (see Table 4) The most
diverse natural wetland samples came from Lake Kanapaha and
the bay swamp, while the highest diversity in the mined
wetlands group was in the Clearsprings samples. In several
cases (Four Corners natural marsh, pasture marsh, Four Corners
mulched plot, Four Corners planted plot, and Sanlan
Juncus-zone. the seed bank had relatively few species and was
dominated numerically by soft rush. This situation more or
less defined the low end of the H'
range.


45
outdoors in large plastic tubs containing sufficient water to
maintain a saturated soil condition.
Seedling emergence by species was monitored through time.
Unidentified seedlings were counted, transplanted to flower
pots, and allowed to mature until they could be identified.
Marsh Transect Study
Six permanently marked transects were established in
October 1982: three each randomly located within the muck
treatment areas and the unmucked, overburden areas (see Figure
7) All transects began in the shallow littoral zone and
extended upslope through the transition zone to the upland
edge. The three muck treatment transects totaled 309 m and
the three overburden transects totaled 275 m. The difference
in total length of the two treatment groups was a result of
the slope differences at the random locations.
The plant communities along the transects were monitored
using a modification of the standard line-intercept method
(Phillips, 1959; Smith, 1980; Canfield, 1941) to record the
percent cover by species along each transect. The standard
method consists of taking observations along a transect line
and noting the identity of any plant touched by an imaginary
plane extending vertically above and below the transect line.
The distance, or interval, of the planar intercept is also
recorded. The individual intervals are totaled for each


122
Table 17. Results of bulk density analysis of mound and
non-mound soils from 2-year old site (n=7).
Standard
Mean
Error
Range
P
Mound
1.19 g/cm3
0.0735
1.00
to
1.43
.05
Non-mound
1.74 g/cm3
0.0473
1.66
to
1.99


101
Table lid. Sweetgum (Liouidambar stvraciflua)
Treatment Means
Plot Assignments
for ANOVA
PR>F Weeded
(ANOVA)
Natural
Enhanced
Legume Colonizers
Plots 15 & 18
7.863
11.057
2.992 4.7
Neglected
NS A
A
A A
Plot 15 Weeded,
6.217
11.057
2.992
4.7
18 Neglected
NS
A
A
A
A


19
Stiritz, 1972; Rogers and Lavigne, 1974; Wali and Kannowski,
1975; King, 1977; Petal, 1978; Levan and Stone, 1983; Culver
and Beattie, 1983). Enhanced nutrient levels in mound soils
are attributed to microbially-mediated mineralization of
organic waste products in the mound (Petal, 1978) This is
supported by the work of Czerwinski et al. (1971), who showed
the abundance of bacteria and fungi in ant mounds is higher
than in the surrounding soil.
Mound-building ants profoundly alter the soil profile
characteristics at their nest sites ( Baxter and Hole, 1967;
Salem and Hole, 1968; Wiken et al., 1976; Wali and Kannowski,
1975; Alvarado et al., 1981; Levan and Stone, 1983). Mound
soil has been shown to differ from nearby soil in bulk
density, porosity, and infiltration capacity (Rogers and
Lavigne, 1974; Rogers, 1972; Wali and Kannowski, 1975).
Through their influence on soils, ants can affect
microtopographic heterogeneity, which can influence species
composition, standing crop, and successional status of the
local vegetation (Petal, 1978; Rogers, 1974; Gentry and
Stiritz, 1974; King, 1977; Culver and Beattie, 1983). Herbs
flourish on abandoned nest sites of harvester ants (Gentry and
Stiritz, 1972) and are known to affect seed distribution.
Ants are known to alter seed shadows in deserts (Bullock,
1974; O'Dowd and Hay, 1980), mesic environments (Beattie and
Lyons, 1975; Handel, 1987; Beattie and Culver, 1981), and
tropical forests (Roberts and Heithaus, 1986). Some plant


86
of the propagules. Cattail has a very small, wind-dispersed
seed? pickerelweed has a heavier, water/animal-dispersed
fruit. On several of the transects, cattail was able to
colonize new areas as they became available with the falling
water levels of the drought of 1985. Cattail appeared more
successful at expanding into open habitat than pickerelweed,
but other taxa were equally opportunistic, especially bulrush
(Scirpus californicus) and dogfennel (Eupatorium
capillifolium).
Major changes in the littoral zone vegetation resulted
from the drought. The overall species richness and total cover
values within the wetland were within the range found in
previous periods, but the manner in which the cover was
apportioned over the various taxa was significantly different.
For both the topsoiled and overburden areas, the cover of many
common species declined and dramatic increases in cover were
shown by other taxa, especially dogfennel and bulrush.
Dogfennel increased profoundly in cover percentages (25
percent and 18 percent for muck treatment and overburden areas
respectively) (Table 7) especially in the deeper areas of the
wetland as the water levels receded. At the peak of the
drought, most of the area that typically had standing water
was vegetated with a well established, monospecific stand of
dogfennel by April of 1985. The timing of the dogfennel
germination means that the seeds would have had to have been
lying dormant in the substrate; as the water level receded,


96
unique in that no seeds germinated regardless of plot or
treatment. Sweetgum had only 6 percent germination and only
33 percent of those survived. Sugarberry had 19 percent
germination, but only 30 percent survival.
The other three taxa had much higher survival rates.
Hickory had 10 percent germination with 75 percent survival.
Germination in cabbage palm was 13 percent with 100 percent
survival. Oak had both high germination (46 percent) and high
survival (87 percent). Because of the difficulty in
accurately distinguishing between young laurel oak and young
live oak seedlings, the two are treated as a single taxon.
The species showed interesting combinations of
germination phenology and survival. The majority of
sugarberry and sweetgum germination occurred before the March
sampling. Additional seeds germinated between March and
October, but mortality in both cases was so high that the
total number of live seedlings was lower in October than in
March (see Figure 16) Germination of hickory and oak had
germination occurred throughout the growing season, with a
larger number of seeds germinating after March. For these two
taxa, the germination phenology combined with low mortality
resulted in a greater number of live seedlings at the second
sampling period than the first. Finally, cabbage palm
demonstrated a different germination pattern, with all
germination occurring after March (see Figure 16).


104
regarding the results will lack some degree of statistical
rigor. In spite of this inability to meet all assumptions
required by theory, the analysis by individual species may
provide valuable insight to the hypotheses being tested that
might otherwise be ignored. Therefore, an ANOVA was run on
the transformed survival data for each species. Magnolia was
not included in the analysis because none germinated in any
plots. The results are again presented in two ways depending
on how plots 15 and 18 were assigned.
Hickory (Table lib) and sweetgum (Table lid) are the
simplest cases; no significant differences were seen among any
of the treatment means in either of the two ways plots 15 and
18 were assigned.
Sugarberry (Table 11c) and oak (laurel oak and live oak
summed) (Table lie) showed similar patterns in response to
two different ANOVA situations and both had significant
differences in at least some of the treatment means. When
plots 15 and 18 were neglected, the two taxa exhibited
slightly differing results. For sugarberry, the weeded,
enhanced legume, and natural colonizer means were not
significantly different, but weeded and enhanced colonizer
means were. For oak, the weeded, natural colonizer and
enhanced legume means were not significantly different from
each other but were all different from the enhanced colonizer
mean, which was also lower.


71
Seed bank samples from all but the youngest sites in the
post-mining landscape fall within or just below the range of
densities and species diversity found in natural wetlands of
Florida, Iowa, New Jersey, and Ontario. The indications from
the results in this study are that it is possible for nature
to reestablish a seed bank of approximately the same size and
diversity as that occurring in some natural marshes, such as
with the Juncus-Polvgonum marsh at Sanlan (30 years old). The
time required for the seed bank to become a "reasonable
facsimile" of a natural marsh as yet may be undefined. The
results at Clearsprings indicate that modest sized seed banks
with higher diversity can develop in 4 years with little
actual marsh reclamation. With some reclamation efforts, seed
banks that compare very favorably in size with natural marshes
can develop in 5 years, as demonstrated at Four Corners.
The seed banks in some of the post-mining wetlands do not
appear to be different in size and species composition from
the natural marshes sampled in this study. However, the actual
vegetation present is not always as diverse, dense, or well
developed, except in cases where muck (topsoil) from a donor
wetland was applied. As an example, the results of line-
intercept transects in mucked and unmucked areas of the marsh
at Fort Green showed that the mucked areas to have 100 percent
cover, while the unmucked areas had less than 30 percent
cover.


Ponlederia cordata
Fall 1082
Spring 1983
Summar 1963
FaN 1983
Spring 1964
Summar 1984
FaB 1984
Summar 1985
Typha latHoUa
Transad 97
1
1. ^
L
Dill
ri
i
i 1 1
60 90 120 ISO
Transad Dtstanca (m)
o
30
180


189
Owen, D. F., and R. G. Weigert. 1976. Do consumers maximize
plant fitness? Oikos 27:486-492.
Patten, B. C. 1975. Ecosystems as a coevolutionary unit: A
theme for teaching systems ecology. In G. Innis (ed.), New
Directions in the Analysis of Ecological Systems.
Simulation Council Proc. Vol. 5, Society for Computer
Simulation. La Jolla, California.
Pearsall, W. H. 1920. The aquatic vegetation of the English
Lakes. J. Ecol. 8:163-201.
Peet, R. K., and N. L. Christianson. 1980. Succession: a
population process. Vegetatio 43:131-140.
Perkin Elmer Corporation. 1980. Analytical methods for the
atomic adsorption spectrophotometry. Perkin Elmer Corp.,
Norwalk, Connecticut. 569 pp.
Petal, J. 1978. The role of ant in ecosystems. In M. V.
Brian (ed.), Production Ecology of Ants and Termites.
Cambridge University Press, Cambridge, England.
Phillips, E. A. 1959. Methods of Vegetation Study. Henry
Holt and Co., New York. 105 pp.
Pickett, S. T. A. 1976. Succession: An evolutionary
interpretation. Am. Nat. 110:107-119.
Pinder, J. E. 1975. Effects of species removal on an old
field plant community. Ecol. 56:747-751.
Platt, W. J. 1975. The colonization and formation of
equilibrium plant species associations on badger mounds in
tail-grass prairie. Ecol. Monog. 45:285-305.
Raup, H. M. 1957. Vegetational adjustments to the instability
of site. pp. 36-48. In Proc 6th Technical Meeting,
International Union for Conserving Nature and Natural
Resources, Edinburgh, Scotland
Rice, E. 1978. Allelopathy. Academic Press, New York, New
York. 352 pp.
Roberts, J. T., and E. R. Heithaus. 1986. Ants rearrange the
vertebrate-generated seed shadow of a neotropical fig tree.
Ecol. 67:1046-1051.
. 1974. Foraging activities of the western harvester
ant in the short grass plains ecosystem. Env. Entomol.
3:420-424.


100
Fa> 1982
Spring 1983
o
100
I
o
100
Summer 1963
I
o
100
FaM 1963
Spring 1984
Summer 1964
I
o
10
J
0
100
I
0
100
FaM 1984
I
0
100
Summer 1985
I
Pontederta corrala
Tranaecl 139
Ti la
Ilk.
30 45 60
Tranaecl Distance (m)
o
15
75
90
Typha iatiloMa
Transect 139
30 45 60
Transect Distance (m)
o
15
75
90


METHODS
Marsh Development
Seed Bank Survey
The seven wetland sites sampled in the seed bank survey
include natural wetlands, and unreclaimed and reclaimed
wetlands on mined lands (Table 2 and Figure 6). At each site,
one to several major vegetation zones were sampled with a 5-cm
diameter, hand core sampler that was pushed into the substrate
to the mineral soil layer. The depth of any overlying organic
layer was noted, and only the upper 10 cm of the core was
retained. Four individual cores were combined to yield a
composite sample, with three composite samples taken in each
vegetation zone selected. Samples were stored in sealed
plastic bags at 4C until they were processed.
All live plant material was removed from the samples to
prevent confusing in seed germination results with any vegeta
tive regeneration. Once the plant material was removed, the
samples were placed in wooden flats (25 cm x 25 cm) containing
approximately 4 cm of sterilized gravel mixed with tailings
sand; the samples were approximately 2 cm deep when spread out
evenly in the flats. The flats were then placed
43


91
colonizer and 18 to weeded) was clearly inappropriate, as plot
15 could be no longer be considered as part of the enhanced
colonizer treatment after it was weeded, but a simpler
solution seemed to be to drop plots 15 and 18 from the
statistical analysis altogether. Although an unbalanced
design may result, any problems of equivocation over the
treatment status of plots 15 and 18 are eliminated. An ANOVA
configuration in which plot 15 is assigned to the weeded
treatment and plot 18 is dropped is also a fairly clearcut
case. As plot 15 was weeded during the later part of the
growing season, the seedlings were growing under weeded
conditions beyond the germination stage.
The seed plots yielded information on germination, the
survival of the germinating seeds, and the growth of the
surviving seedlings. Total germination was estimated with
data from the two sampling periods in March and October 1984
(Table 9). Because the location of each seedling in the plot
was recorded at the time of sampling, the fate of any given
seedling could be followed through time. Thus, the mortality
of germinating seedlings could be estimated and an idea
developed of the phenology of germination (Table 10 and Figure
16) .
Overall, 20 percent of the seeds planted did germinate
and percent of those germlings survived through the first
growing season. The individual species showed a full range
of response in both germination and survival. Magnolia was


144
among tree seedlings and herbaceous plants may have been more
intense in the enhanced treatment plots, thus reducing
survival and possibly germination. Allelopathic inhibition of
either growth or germination of woody plants by the species
added is also possible. One of the enhanced colonizers,
Andropogon virainicus. has been reputed to produce allelo-
chemicals that inhibit the growth of other plant species
(Rice, 1978).
Effect of Erosion. When the major erosion problems began
in early January 1984, the extent and degree of erosion on
site were assessed and mapped. An examination of the map and
field notes from this time show that eight seed plots were
affected by erosion rills. By chance, the affected plots were
evenly distributed among the four treatments. Several plots
affected by erosion exhibited low survival and others showed
high values. Only in two cases were seeds observed to have
been washed out of plots (numbers 12 and 13) and these were
replaced by hand. However, this does not preclude the
possibility of some seeds having been lost completely from
some plots or washed from one plot into a down-slope plot.
One indication that there was no significant movement of seed
between plots is that no individuals of any of the planted
legume species were ever found in plots other than the ones
in which they were placed.
The germination and survival results for the individual
species were varied and less clear in support of one of the


41
to 30 cm. Approximately 15 percent of the littoral zone
received the muck treatment.


140
sugarberry and sweetgum, since these species produce a rather
delicate seedling.
Effect of site conditions. Seeds respond to
environmental cues to germinate. In some cases, dormancy must
be overcome. It is possible that the conditions in the field
plots were more generally suited for some species than others.
Effect of seed predation. Losses of seed and young
seedlings could also bias the germination results. Seed
losses to birds and small mammals are always a danger to any
direct-seeding operation and are one of the primary causes of
low germination in natural conditions, but for large-seeded
species, this is also a necessary cost of dispersal. Freshly
disturbed soil often attracts animals that consume seeds as
part of their diet. Armadillos were observed on the study
plots and raccoons, field mice, and feral hogs were also
present in the reclamation area.
Two factors were observed to lower the germination
potential of hickory, one physical and the other biological.
The hickory nut is very large and was easily winnowed out of
the soil during heavy rain. This process may have been aided
by the removal of hickory nuts by armadillos. Tracks and
signs of soil disturbance in the plots by these animals were
seen on several occasions, and the signs were usually
associated with the presence of only the outer husks of the
hickory nut.


39
minimum design grade and then backfilled, simulating
reclamation. Four test plots were established as follows:
1. Plot 1. Control plot, graded and left for natural
revegetation.
2. Plot 2. Hand-planted with plant material taken from
nearby natural marsh, including maidencane (Panicum
hemitomon) pickerelweed (Pontederia cordata) and Juncus
effusus.
3. Plot 3. Mulched 30 cm deep with donor muck from a nearby
marsh.
4. Plot 4. Tree plot where 95 trees comprising 16 different
species were transplanted from a donor site on Alderman
Creek.
Whidden Creek Reclamation Area. The Whidden Creek area
was mined by Gardinier Phosphate in 1982 and 1983. The area
was reclaimed in 1983 using an integrated landscape approach,
that sought to create a small drainage basin discharging to
Whidden Creek.
Tiger Bay Reclamation Area. The Tiger Bay area was mined
by International Chemicals and Minerals, Inc. (IMC) in 1982
and 1983. The area was reclaimed in 1983 as a land-and-lakes
area typical of the industry's reclamation practice.
Clearsprinas Wetland Demonstration Project. Work on this
18-ha wetland demonstration project began in 1978. The
project was a joint effort of IMC, the Florida Game and
Freshwater Fish Commission, and the U.S. Fish and Wildlife
Service. The site adjoins the Peace River and was designed
to establish physical site characteristics similar to those
that produce and maintain floodplain wetlands. Basins were


139
Upland Forest Plots
Seed Germination and Survival
The germination results and accompanying survival rates
for the seed highlight several points. First, germination
rates between species differ widely under field conditions,
as shown by the two extremes of magnolia with no seeds
germinating and oaks with nearly 100 percent germination.
Germination was low for hickory, sugarberry, sweetgum and
cabbage palm. Factors apparently affecting germination
success include seed quality, site condition, seed predation,
and seed size. The survival of individuals that germinated
exhibited interesting species-specific trends that appear
related to seed size and seedling adaptations.
Effect of Seed Quality. Sugarberry, sweetgum, hickory,
cabbage palm, and magnolia seeds had been collected a year
before the study and stored dry at 4C; oak acorns were
collected the month before planting and stored outside in
potting soil. The storage regime, as well as the initial
quality of the seed, could have had an effect on germination
potential. Many of the acorns were nearly germinating when
planted. Also, because germination was determined only from
the two sampling periods in March and October, any seeds that
germinated but survived only a short time for would have been
overlooked. This factor would have been more critical for


Figure 5. Energy circuit language diagram of ant model.


170
forming rational and cost-effective land reclamation
techniques and policies that will enhance and direct the
successional process on mined lands.
Using the five individual paradigms as design principles,
some of the implications of each for the reclamation of strip
mined land are discussed in the following section.
Inhibition
There are many documented examples of inhibited or
arrested succession on mined lands. These studies generally
describe an arrested succession in which the initial species
composition of primary invading species is perpetuated. The
Fort Green marsh study indicated that in the absence of
disturbance, the initial vegetation pattern and species
composition are maintained for some time, possibly even long
term.
Initially established vegetation may be able to resist
invasion by other species through maximum performance for
existing environmental conditions. Under appropriate
conditions, even slow-dispersing, late successional species
are able to become established and occupy the available space.
Once the available space is filled, opportunity for invasion,
even by aggressive species capable of inhibiting succession,
is limited. Consequently, it is feasible to establish
self-maintaining, stable, wetland and upland communities


72
Marsh Transect Study
Water levels and hvdroperiod. Daily water levels in the
Fort Green wetland were summarized as mean monthly values for
the period of the study, August 1982 to December 1985 (Figure
11) Evident trends include the typical annual hydroperiod
cycle and the drought that began in late 1984 and continued
through late summer of 1985.
The typical annual hydroperiod cycle began with low water
in early winter followed by a rise in late winter or early
spring and a spring peak. The cycle continued with a summer
decline, a late summer peak, and a fall decline. With the
exception of the 1985 drought cycle, the annual hydroperiod
in the basin has typically varied about 0.3 m between lows of
approximately 36.42 m msl to peaks of about 36.67 m msl.
From the fall of 1984 through the spring 1985 a drought
occurred that was unrelieved by spring rains. Water levels
in the basin declined steadily from August 1984 to June 1985,
when they reached a monthly low of 35.37 m msl. The late
summer rains of 1985 brought the water level up to the typical
late summer peak by August.
The transect elevation data were used to generate
individual transect profiles (see Figures 12 and 13) Four
of the transects (97, 115, 125, and 130) began at elevations
between 36.06 and 36.27 m, while transect 105 started at a
lower elevation (35.60 m msl) and transect 139 started at a


152
two studies imply that the colonizing herbs had little effect
on perennial herb species.
None of the four studies found any support for the relay
floristics model, but all dealt with only herbaceous plants
in an old-field succession sequence. As noted earlier, relay
floristics may be most appropriate for describing primary
succession and the establishment and growth of late
successional woody plants.
The relay floristics model predicts that later
successional woody species only enter the developmental cycle
after harsh conditions have been ameliorated by the colonizing
vegetation. The pioneer plant community is commonly assumed
to play a role in the accumulation of soil organic matter,
development of soil profiles, building of vegetation structure
to provide shade and reduction of erosion from raindrops,
buildup of soil nutrient levels, development of recycling from
consumers, and development of symbiotic relations
(plant/mycorrhizae, for example). Evidence in support of the
relay floristics model comes from studies of primary
succession on newly exposed surfaces. Crocker and Major (1955)
and Lawrence et al. (1967) have suggested that the
characteristics of soils newly exposed by a retreating Alaskan
glacier make the establishment of plants extremely difficult.
Pioneer species that are able to colonize will ameliorate
these conditions, reducing pH, increasing nitrogen, adding a
layer of organic matter over the hardpan, and reducing


Figure 3. Energy systems diagram of succession: (a) with some of the main pathways of
organization, seeding, and nutrient cycle; (b) control in "initial floristics"; (c)
control with inhibition; (d) control with "relay floristics"; (e) control with
coevolution, pathways permanent; and (f) controls from self-organization and
reinforcement from animals and larger surrounding system.


25
straightforward, objective, scientific consideration. Ecology
and the succession concept may be in the midst of a revolution
(McIntosh, 1983) and specifically a change in paradigms, which
Kuhn (1970) has described as the way a scientific discipline
progresses.
A common and idealized image of a scientific discipline
is that it is universal, objective, and unbiased, with free
communication and mutual comprehension among its members.
Historians of science show this to be a simplistic and
inaccurate view, and discuss the hypothesis of the "invisible
college" as the basis of the organizational patterns
associated with major advances and changes in paradigms within
a scientific discipline (Crane, 1972; Griffin and Mullins,
1972). The invisible college hypothesis argues that any
discipline, especially one in a state of change, is subdivided
into loose networks of scientists with varying degrees of
cohesiveness and continuity. According to Griffin and Mullins
(1972) such networks conform to the following criteria:
1. Their members believe they are making major changes in
concept or methodology and the word revolution is much
in evidence.
2. Members do not consistently observe the attitude of
disinterested objectivity typically associated with
scientists and may be passionate and one-sided advocates
of a "ruling theory."
3. There is commonly a close, even somewhat closed, informal
communication network within the network.
One or more outgroups are typically recognized and
increasingly opposed as the network becomes more tightly
organized.
4.


106
Table 12. Comparison of mean seedling height growth
four experimental treatments (weeded,
colonizers, legume, enhanced colonizers),
compare following an ANOVA, using Duncan's
range test. Means with the same letter
significantly different (p <.05).
Table 12a. All species summed
(cm) for
natural
. Means
multiple
are not
Treatment
Means
Plot Assignments PR>F
Weeded Natural
Enhanced
for ANOVA (ANOVA)
Legume Colonizers
Plots 15 & 18
Neglected
.0001
7.78 6.4
A
6.26
5.8
B
B
B
Plot 15 Weeded,
18 Neglected
.0001
8.02 6.4
A
6.26
5.8
B
B
B


17
Population ecologists view non-trophic interactions as
byproducts of the evolutionary process. Wilson (1980)
described the problem as one in which traditional
investigators within the discipline of population ecology
assumed that the community structure was already in place.
They then focused on relatively superficial forms of
competition and predation, while ignoring the structure that
actually determined the parameter values of the models.
Productivity in ecosystems depends on recycling and
conservation of nutrient resources. The actions of consumers
may cause a nutrient in short supply to become relatively more
available. When primary production is nutrient-limited,
heterotrophic activity, which accelerates mineralization, may
help increase
it. The
importance
of
heterotrophs
as
regulators
of
ecosystem
processes
far
outweighs their
importance
as
measured by
calories or
grams of matter,
but
rather lies in how their characteristics affect or regulate
ecosystem processes (Chew, 1974; Odum, 1982).
Numerous examples can be found of the regulatory role
played by consumers. Vertebrate herbivores have been shown
to increase productivity of grasslands (McNaughton, 1975).
Platt (1975) showed the influence that badger mounds have on
soil properties and the pattern and distribution of some plant
species. Burrowing rodents can act as nutrient pumps,
bringing materials to the surface from below (Abaturov, 1972) .
In forest soils, litter accumulated and decomposition slowed


Pontederia cordata
Transact 115
Fall 1982
Spring 1963
Summer 1983
Fall 1983
Spring 19M
Summer 1964
FaM 1984
Summer 1985
Tranaect Distance (m)
Tvpha latHoUa
Tranaect 115
Tranaect Distance (m)
oo


109
Table 12d. Sweetgum (Licmidambar stvraciflua)
Treatment Means
Plot Assignments
PR>F
Weeded
Natural
Enhanced
for ANOVA (ANOVA)
Legume Colonizers
Plots 15 & 18
6.0
5.0
4.0 4.5
Neglected
NS
A
A
A A
Plot 15 Weeded,
o

VO
o

in
4.0 4.5
18 Neglected
NS
A
A
A A


ACKNOWLEDGMENTS
I thank my faculty committee members Dr. G. Ronnie Best,
Dr. H. T. Odum, Dr. Clay Montague, Dr. Steve Humphrey, and
Dr. Warren Viessman for their guidance.
The research was supported by Florida Institute of
Phosphate Research grant number 81-03-008, "Enhanced
Ecological Succession Following Phosphate Mining," G. R. Best
and H. T. Odum, principal investigators.
Several mining companies provided support and information.
Marsh studies at Fort Green were in part supported by Agrico
Mining Company. Mobil Chemical Company, International
Minerals and Chemical Company, Gardinier Phosphate Company,
and W. R. Grace and Company provided access to study sites.
Special thanks go to those who assisted with field work,
Pete Wallace, Mel Rector, Alfonso Hernandez, Juan Hernandez,
Bob Tighe, Jim Feiertag, and Tim King. The late Bill Coggins
ran all the SAS analyses. Dr. Ron Myers allowed the use of
unpublished data on seed banks at Lake Kanapaha.
Marla Mittan helped with technical editing. I wish to
thank CH2M HILL for making its resources available during the
final phases of this dissertation.
ii


50
downslope neighbors. All major erosion rills on the site were
mapped as an aid to interpreting results. In addition,
several rills that had developed through the seed plots were
diverted to interplot areas with a shallow, diversion trench.
Once colonizing vegetation began to appear in early spring of
1984, it afforded a modest degree of soil stabilization and
the severity of the erosion diminished considerably.
Direct-Seeded Plots.
Seeds of seven species were used in the direct-seeded
test plots seeds: sweetgum (Licruidambar stvraciflua) cabbage
palm (Sabal palmetto), live oak (Ouercus virginiana), laurel
oak (Ouercus laurifolia), southern magnolia (Magnolia
grandiflora), sugarberry (Celtis laevigata), and pignut
hickory (Carva glabra). These seven taxa were considered
representative of common mesic hardwood species of central
Florida.
The seeding rate per plot was 50 seeds per species,
yielding 350 seeds per plot. Each plot planting area was 9 m2
(3 m by 3 m), resulting in a density of 39 seeds/m2.
The plots were arranged in a 6 by 3 grid with two of the
plots remaining unused (see Figure 8) Treatments were
assigned randomly to the plot grid. Each total plot was 7 m
by 7 m, which allowed for a 2-m buffer all around the 9m2
planting area. The seed mix was hand broadcast onto the plots
after the soil was disturbed, and the treatment seeds were


169
1980) but it is clear that the synthesis is far from
complete. The continuing contradictions about succession
after many decades of study suggest that ecology and the
succession concept may be in the midst of a change in
paradigm. The single concept paradigms of succession
(inhibition, initial floristics, relay floristics in
particular) appear to be flawed and a new paradigm will likely
emerge from a more eclectic synthesis that incorporates and
unifies the concepts of several paradigms. It is clear that
an explanation of the cause and mechanism of succession, and
development of a reasonable consensus on a paradigm of
succession, will require a careful analysis of the historical
background, biases and premises, and philosophy of the idea
and its practitioners, critics, and proponents.
Until such time that a unifying paradigm of succession
is constructed and widely accepted, it is also clear that the
five competing paradigms examined in this dissertation can
provide a theory-based guide for the reclamation of disturbed
land. Reclamation should be viewed as type of engineering
design based on ecological principles. The five paradigms
reviewed in this dissertation can be used as ecological
principles for guiding reclamation design. Using the
paradigms to guide our reclamation design efforts should help
us create functional, self-maintaining ecosystems that
integrate with the surrounding landscape. A clear
understanding of succession also provides an opportunity for


87
Table 7. Percent cover of Eupatorium capillifolllum and
Scirpua callfornicus on muck treatment and overburden
transects, Fort Green marsh,eight sampling periods between
fall 19S2 and summer 1985.
Eupatorios capillifoliua Scirpus callfornicus
Sampling
Period
Muck
Transects
Overburden
Muck
Transects
Overburden
Fall 1982
6



Spring 1983
0.2



Summer 1983
0.4
0.1


Fall 1983
0.1
<0.1


Spring 1984
0.1
0.2

0.2
Summer 1984
0.3
0.2
0.2
0.3
Fall 1984
1
0.3
0.9
0.9
Summer 1985
25
18
6
9


135
Another example of the process is found with cypress domes
which may influence the shape and depth of their own basins
through the production of acid waters, that percolate down and
cause solution of the underlying limestone (Odum, 1984).
Also, the sawgrass marshes of the Florida Everglades are fire-
adapted communities whose continued survival depends upon fire
(Wade et al., 1980). The sawgrass plants accumulate fuel in
the form of standing-dead leaf litter, and when sufficient
litter has accumulated and conditions are right, a fire may
occur. Fire is an allogenic process, but the timing,
frequency, and severity of the fire are influenced by the
growth characteristics of the sawgrass.
Another excellent example of this kind of feedback loop
is discussed by Weller (1981). In midwestern prairie pothole
marshes, the vegetation is periodically destroyed by muskrats.
New emergent vegetation cannot become established until a dry
year exposes the substrate. A typical succession follows
until cattails out-compete the other plant species. This sets
the stage for another muskrat population explosion. The cycle
has a 6- to 8-year frequency that depends on both the biotic
vegetation-muskrat interaction and the abiotic water level-
climate cycle.
Eclectic Wetland Succession Paradigm
Evidence supports the conclusion that both allogenic and
autogenic forces act to change wetland vegetation. A paradigm


187
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impact of the leaf cutter ant Atta colombica on the energy
flow of a tropical wet forest. Ecol. 54:1292-1301.
Majer, J. D., J. E. Day, E. D. Kabay, and W. S. Perriman.
1984. Recolonization by ants in bauxite mines
rehabilitated by a number of different methods. J. Appl.
Ecol. 21:355-375.
Marks, P. L. 1974. The role of pin cherry (Prunus
pennsvlvanica) in the maintenance of stability in northern
hardwood ecosystems. Ecol. Monog. 44(l):73-88.
May, J. T., C. L. Parks, and H. F. Perkins. 1973.
Establishment of grasses and tree vegetation on spoil from
kaolin clay strip mining. In R. J. Hutnik and G. Davis
(eds.), Ecology and Reclamation of Devastated Land, vol.
2. Gordon and Breach, New York.


134
effects of changes in depth frequency and duration of
flooding. The organic sediments also provide a rooting
medium, seed storage medium, and microfaunal habitat that is
quite different from the underlying mineral substrate.
The model fails to recognize that wetlands tend to change
with time from "young" to "older," more mature stages (Mitch
and Gosseklink, 1986). Young stages after establishment are
characterized by (1) plant species that are opportunistic,
early colonizers capable of being established from seed and
growing in a variety of different habitats, (2) soils that are
typically mineral in nature with low organic matter content,
and (3) subsurface hydrology and chemistry controlled by the
mineral soil. As the system ages, it becomes more "mature":
(1) the plant community may become dominated by species more
characteristic of mature wetland systems, (2) the wetland
soils may gradually change and gain an increasing amount of
organic matter, and (3) the subsurface hydrology and chemistry
may change in response to the changes in wetland soils.
Maturation is to a large extent the action of the
autogenic processes within the wetland. The accumulation of
sediments and the formation of an organic soil is due to
litter production, decomposition, and the depth and duration
of flooding. By building the soil structure, the biological
community provides a feedback to the environmental sieve and
modifies its effects. The mature community has a greater
degree of internal control than the young community.


14
Leek and Graveline, 1979), seeds remain dormant, yet viable,
in the seed bank during periods in which environmental
conditions are unfavorable for germination, growth, and
development of the population. In wetland and upland
communities, seed banks provide a mechanism for rapid recovery
from catastrophic mortality resulting from fire (Johnson,
1975), clear-cutting (Marks, 1974), and drought (Myers, 1983).
Marks (1974) has shown that the rapid response of pin cherry
to clear-cutting in the Hubbard Brook ecosystem helped
minimize the effect of canopy removal on nutrient losses from
the ecosystem. Egler's initial floristic hypothesis portrays
old-field succession as a seed bank response.
The van der Valk wetland model can be reformulated using
energy circuit language (Figure 2). Van der Valk's 12 life
history categories are simplified to mudflat annuals, emergent
macrophytes, and aquatic macrophytes. The actual composition
of the wetland is determined by the interaction between the
existing plant community, the propagules present, and
environmental conditions. Logic switches are used to indicate
the actions of the "environmental sieve."
Role of Consumers
Various roles are attributed to consumers in ecosystems
beyond simple trophic relationships of herbivory and
predation. These non-trophic interactions typically involve


I certify that I have read this study and that in my
opinion it conforms to acceptable standards of scholarly
presentation and is fully adequate, in scope and quality, as
a dissertation for the degree of Doctor of Philosophy.
G. Ronnie Best, Chairman
Associate Research
Scientist,
Environmental Engineering
Sciences
I certify that I have read this study and that in my
opinion it conforms to acceptable standards of scholarly
presentation and is fully adequate, in scope and quality, as
a dissertation for the degree of Doctor of Philosophy.
Howard T. Odum
Graduate Research
Professor,
Environmental Engineering
Sciences
I certify that I have read this study and that in my
opinion it conforms to acceptable standards of scholarly
presentation and is fully adequate, in scope and quality, as
a dissertation for the degree of Doctor of Philosophy.
Environmental Engineering
Sciences
I certify that I have read this study and that in my
opinion it conforms to acceptable standards of scholarly
presentation and is fully adequate, in scope and quality, as
a dissertation for the degree of Doctor of Philosophy.
Professor,
Forest Resources and
Conservation


126
mechanism. The third regenerative strategy employed by
wetland plants, the production of numerous wind-dispersed
seeds, is useful in colonizing near and distant open areas,
especially those that lack a seed bank.
Many species employ more than one strategy. Seeds of
most wind-dispersed species remain viable at least for short
periods of time in a seed bank. Cattail uses all three
regenerative strategies; it is capable of rapid vegetative
growth and produces prodigious amounts of wind-dispersed
seeds, which are also capable of lying dormant in a seed bank.
The perennial macrophytes present within the wetland
zones sampled may rely on vegetative expansion as their
primary regenerative strategy. Alternatively, their seeds may
have been present but in relatively scarce amounts or a
patchy distribution. As noted earlier, all root and rhizome
material was removed from the samples. In hindsight, it would
have been instructive to retain the root/rhizome material and
check for sprouting.
Even for species that use vegetative expansion as the
primary regenerative strategy, the production of viable seed
represents an essential component of the total regenerative
strategy.
Formation and Stability of Macrophyte Communities
In regard to the pattern of succession observed at the
Fort Green marsh, the vegetation dynamics described in this


28
plant community establishment in wetland and terrestrial
communities and interpret the results and observations through
competing paradigms of succession (initial floristics,
inhibition, relay floristics, coevolution, and self
organization) (2) to determine the role played by mound
building ants in the developing community and assess this role
with the prevailing paradigms, and (3) identify possible
technigues for enhancing succession on strip-mined land.
These overall research objectives were addressed in three
separate but related field studies.
Marsh Development
Seed bank survey. As an initial step in understanding
and enhancing the design of self-maintaining ecosystems, seed
bank dynamics were examined. A survey was made (1) to assess
the size and species composition of seed banks in selected
marsh ecosystems from natural and post-mining landscapes, (2)
to identify the ecological role and significance of seed banks
in marsh community dynamics, and (3) to evaluate the
feasibility of establishing marsh ecosystems by helping form
seed banks.
Marsh transect study. Transects were used to compare the
herbaceous component of the wetland that developed from
natural processes to that created by spreading muck from an
onsite donor marsh. Stages of vegetation establishment were


Table 10. Summary of germination and survival results from Gardinier seed plots. The
percentage survival is here defined as the percentage of all seeds that
germinated which survive to the end of the growing season.
Mill UuUutor £uu Sibil imoli totrcii ToUl
Cuiolatlie Sorilial Caanlatlie Surilial Coaulaliie Survival Cuaalative Survival Cuiulative Survival emulative Survival emulative Survival
Treatueit leraiaatioa leruiiatloa feniiatioi (eriiaatiou feriluatiou lenliatloi (eraluatiou
i m > m i m m i m id o m i to i m i 10 i it) i to i id i m
Iibauced
42
(21)
1
(10
11
(10
2 (10
If
( 0
10
(62)
22
111)
22 (100)
0
0
If 4
(91)
141 (07)
2S7 IOS (72)
Coloulied
22
(10
S
(10
It
(0
1 (SO
24
(12)
11
(TS)
20
(10)
20 (100)
0
0
20S
10)
171 (01)
297 222 (7S)
Needed
](
(10
21
(SO
14
(7)
S (10
21
(US)
20
(11)
40
(20)
40 (100)
0
0
100
(4S)
167 (91)
291 24f (04)
Lefuaed
44
(22)
1)
(20
(
(1)
1 07)
U
I 0
11
(72)
21
(11.S)
21 (100)
0
0
190
(47)
Iff (07)
201 216 (77)
1S4
00
47
(10
49
(0 1
if (10
0
(10
0
(7S)
10S
(ID
10S (100)
0
0
739
(40
647 (07) 1120 (20) 069 (77)
VO
u>


171
dominated by late successional species able to resist invasion
by aggressive colonizers.
The arrested, or inhibited, succession observed on mined
lands may be largely attributable to restrictions on
dispersal. It is apparent from the field studies reported
here that late successional plant species can become
established, grow, and survive under early successional
conditions. The successional process on disturbed lands can
be influenced and enhanced by facilitating the dispersal and
establishment of the more slowly arriving, later successional
components.
For reclamation, the emphasis should be on: (1)
predicting the soil type and soil moisture conditions
(hydroperiod in wetlands) of the reclaimed system and using
these as guides for determining the type of vegetation that
could be supported; (2) controlling aggressive species capable
of inhibiting succession; and (3) overcoming the dispersal
limitation of many late successional species to get these
species established at the start. On wetland sites, the
application of peat or muck from donor marshes has been
successful in these areas but may not always be feasible
because of the quality of donor material or budgetary
constraints in transporting the material. In such situations,
planting an array of long-lived perennials in patches can
accomplish these goals. At Fort Green large stands of
cattail, pickerelweed, and bulrush developed from individual


Fiqure 16. Number of germinated seeds on tree
Seeds planted in fall of 1983 and plots sampled
species planted at Gardinier plots,
in spring and fall of 1984.


188
McClanahan, T. R. 1984. The effects of dispersal on
ecological succession and optimal island size. M. S.
Thesis. University of Florida, Gainesville.
McCormick, I. 1968. Succession. Via 1:1-16.
McIntosh, R. P. 1980. The relationship between succession and
the recovery process in ecosystems. In J. Cairns (ed.),
The Recovery Process in Damaged Ecosystems. Ann Arbor Sci.
Pub., Ann Arbor, Michigan.
. 1981. Succession and ecological theory. In
D. C. West, H. H. Shugart, and D. B. Botkin (eds.), Forest
Succession:Concepts and Application. Springer-Verlag, New
York.
McNaughton, S. J. 1979. Grazing an optimization process:
grass-ungulate relationships in the Serengeti. Am. Nat.
113:691-703.
Mitch, W. J., and J. G. Gosselink. 1986. Wetlands. Van
Nostrand Rheinhold Co., New York. 537pp.
Myers, R. 1983. Unpublished seed bank data from Lake
Kanapaha, Alachua County, Florida. University of Florida,
Gainesville.
Odum, E. P. 1969. The strategy of ecosystem development.
Science 164:262-270.
Odum, H. T. 1983. Systems Ecology: An Introduction. John
Wiley & Sons, New York.
. 1984. Summary: Cypress swamps and their regional
role. In K. C. Ewel and H. T. Odum (eds.), Cypress Swamps.
University Presses of Florida, Gainesville.
Odum, W. E. 1988. Predicting ecosystem development following
creation and restoration of wetlands. In J. Zelazny and
J.S. Feierabend (eds.), Increasing our Wetland Resources.
Proceedings of Conference. National Wildlife Federation,
Washington, D.C.
O'Dowd, D. J., and M. E. Hay. 1980. Mutualism between
harvester ants and a desert ephemeral:seed escape from
rodents. Ecol 61:531-540.
Olson, J. S. 1958. Rates of succession and soil changes on
southern Lake Michigan sand dunes. Bot Gaz. 119:125-170.
O'Neil, R. V. 1976. Ecosystem persistence and heterotrophic
regulation. Ecol. 54:1244-1253.


165
grams per kilogram in overburden soils (Wallace, 1988). The
heterogenous nature of overburden soils led to considerable
variation among samples.
No clear differences in pH were observed between the two
soil groups. Wali and Kannowski (1975) found ant activity
increased pH in predominantly acid soils and decreased pH in
predominantly alkaline soils. It is likely that there has
not been sufficient time for ant activities to have an effect
on the young overburden soils at the three sites studied.
Also, the heterogeneous nature of these soils may contribute
to a large statistical variance. It is expected that a pH
reduction attributable to activities of the colony will become
apparent through time.
Plant growth enhancement. The results of the two
plant growth experiments demonstrate that elevated nutrient
levels in mound soil can translate into enhanced plant growth.
The higher cations and nitrogen in mound soil enhanced growth
for both a grass (Paspalum urvillei) and woody plant
(Liquidambar stvraciflua). This supports the field
observation that herbaceous plants, especially grasses,
growing on mounds were more robust than those on adjacent non
mound soils. Indirect evidence is also provided to support
the existence of non-trophic feedbacks as shown in the
feedback loop between plants and ants (see Figures 4 and 5).


Environmental Sieve (State: Drawdown)
WETLAND
VEGETATION
fit
" AD-II
A S II
-PD-II
- PS-II
t
Potentially
Extirpated
Species
AS- AS- PS- PS- VS- VS-
I II II II It
HEJY
A-Annual
P-Perennial with Limited Life Span
V-Vegetatively Progated Perennial
D-Dispersal Dependent Species Short-Lived Seeds
S-Seed Bank Species Long-Lived Seeds
I -Species Established Only in Absence
ol Standing Water
11-Species That Can Be Established In Standing
Water


Environmental
I Conditions J


56
Soil organic matter was determined by the Walkey-Black
wet digestion method (Black, 1965).
Nitrogen was measured as TKN by the semi-micro kjeldahl
procedure, a 1-g sample of air dried soil 7 ml of sulfuric-
salicylic acid was added. After each sample was allowed to
set for 30 minutes, 1 g of sodium thiosulfate was added and
2 g of catalyst were added. The samples were then heated in
a block digester for 5 hours. After digestion, 20 ml of NaOH,
15 ml of boric acid, and 2 drops of indicator were added to
each sample. The samples were then distilled to 60 ml, and
titrated with 0.05 normal sulfuric acid.
A dilute double acid solution (0.025 N H2S04 + 0.050 N
HCl) was used to determine extractable levels of calcium,
magnesium, manganese, potassium, and sodium. Cation levels
in the extracts were measured by atomic absorption-emission
on a Perkin-Elmer model 500 using standard operating
techniques (Perkin Elmer, 1980). One ml of a 10,000 ppm (1%)
lanthanum chloride (LaCls) solution was added to each dilution
series of extract, which resulted in a 1000 ppm solution (.1%)
in each sample. This procedure was necessary to control for
interferences by silicon, aluminum, phosphate, and sulfate,
which depress sensitivity in analyses for these cations.
Equal amounts of lanthanum chloride were also added to
standards and controls before analysis.


125
and fruiting bodies of many macrophytes (pickerelweed, water
hyacinth, cow-lily (Nuphar luteum), white water-lily (Nvmphaea
odorata)/ Saaittaria. and Peltandra virginica are large enough
to be easily seen, and no large seeds were observed in any of
the samples.
The question arises of how pickerelweed, Saaittaria. cow-
lily, and white water-lily could be present in at least a few
of the wetlands sampled, if none of their seeds were detected
in this assay. It may be beneficial to discuss the species
present in the seed bank samples versus those conspicuous by
their absence in terms of successional status and life history
characteristics of the adult, established phase and juvenile,
regenerative phase. Regenerative strategies may be related
to successional status.
Formation of a persistent seed bank represents only one
of three regenerative strategies used by wetland plants; the
others are vegetative expansion and production of numerous
wind-dispersed seeds. Generally, vegetative expansion, is
successful where the adult plant is already established. Most
long-lived macrophytes are capable of vegetative expansion
which allows for rapid colonization of open space, such as
small patch disturbances within a large existing stand of
marsh vegetation. In habitats characterized by chronic but
unpredictable disturbance (fire, flood, or drought), where
vegetative structure is destroyed over large areas, the
persistent seed bank is typically the primary regenerative


88
the dogfennel seedbank responded and a complete cover
developed.
Bulrush also increased in cover at the north end of the
basin, as seen in 1985 results from transects 125, 130, and
139. As with dogfennel, the increase occurred in normally
flooded areas lacking established emergent vegetation. The
area of bulrush invasion was also a site of noticeable
invasion by Saaittaria lancifolia and dogfennel. These areas
showed little to no invasion by cattail, which was well
established in the vicinity and had been spreading
vegetatively for the previous two seasons. Bulrush was able
to colonize and establish in an area that appeared to be ideal
for cattail invasion.
The transect specific elevation profiles and inundation
frequencies were used to compare the zones of establishment
of cattail and pickerelweed (Table 8) The two taxa do occupy
roughly the same zone within the wetland based on the patch
establishment (Figures 15a through 15f) from approximately
elevation 36.33 to 36.58 m msl and with an inundation range
of 40 to 80 percent. The results from transect 105 are
particularly interesting because the mulch was spread in
deeper areas, down to elevation 3 5.51 m msl, that were
permanently flooded. These deepwater stands were neither
invaded nor encroached upon by cattail during the study
period. They were also not ephemeral in nature, remaining
constant throughout the study although they showing similar


33
decrease in the item at the arrowhead. The ant model depicts
two positive feedback loops, one linking plants-ants-microbes
and one linking mounds-soil-water infiltration. The arrows
represent causal relationships that can be experimentally
evaluated.
An energy circuit language formulation of the ant model
(Figure 5) also provided a summary of ecosystem components and
energy/material pathways for directing research efforts.
Research guestions were:
1. Do mound-building ants concentrate nutrients in the
landscape?
2. If they do concentrate nutrients, does this provide a
feedback to the primary producers (plants), establishing
a non-trophic interaction or indirect effect and
eventually a feedback to themselves?
3. What function does mound-building work serve for the
developing ecosystem?
4. If ants are found to provide positive feedback to the
developing ecosystem, are there ways to further stimulate
feedbacks and enhance succession?
Description of Study Sites
Eight study sites in central Florida were used in the
three phases of the research (see Table 1 and Figure 6) .
Seven of the sites were within Polk County and one in the
northeast Manatee County in the Four Corners area. A brief
description of each site is provided below.
Pasture Marsh. This marsh was approximately 1.0
hectare in size and located on the Mobil Chemical Company's


51
added if required were. The plots were then raked lightly to
incorporate the seeds into the substrate.
The seed plots were measured in March and October 1984
and the species, height, and growth condition of each seedling
in each plot was recorded. The location of each seedling was
recorded as well so the fate of individuals could be followed.
Seedling Transplant Plots
In the seedling test plots, three mesic hardwood species
were used: sweetgum, live oak, and cabbage palm. The
planting stock for sweetgum and cabbage palm was 8-month-old
containerized seedlings grown in overburden soil. The oak
seedlings were 1-month-old bare root seedlings.
Ten individuals of each species were used in each of the
16 seedling plots, yielding 30 trees per plot and 480
seedlings total. Tree seedlings were planted after the soil
was disturbed and any treatment seeds were added. The 30
trees were randomly assigned to the grid, and the same
planting schematic was used in all the plots (see Figure 9).
The total area of each seedling plot was 8 m by 9 m,
allowing for a 2-m buffer around an actual planted area of 4
m by 5 m. Seedlings were planted on approximately 1-m
centers.
The severe winter freezes of December 1983, and January
February 1984 killed many of the planted seedlings. As the


26
5. A network is commonly identified with a leader who may
provide intellectual and/or organizational coherence.
The work that the network associates itself with
generally has originated, or is centered on a particular
place with a more or less well defined origin and time
span.
Some of the confusion and contradictions concerning
succession may be attributed to a lack of understanding of the
history and sociology of the succession concept and the
origins and evolution of the competing paradigms, or
conceptual models. Confusion often arises from ignorance,
as proponents of a "new" view may be unfamiliar with early
work in the field, current thinking within other groups in the
field, or their nomenclature and terminology. The invisible
college hypothesis may help explain the divergent positions
in ecology specifically concerned with succession.
A scientific community upholds an old paradigm in spite
of its inadeguacies and contradictions until a new and better
one emerges and is accepted. The paradigms of succession
appear to be flawed and a new paradigm will likely emerge from
a more eclectic synthesis. It is clear that an explanation
of the cause and mechanism of succession, and development of
a reasonable consensus on a paradigm of succession, will
require a careful analysis of the historical background,
biases and premises, and philosophy of the idea and its
practitioners, critics, and proponents.
As a framework for formulating this bridging paradigm,
McIntosh (1981) provided a number of questions to be answered:


67
but absent at site 1. The index has a range of 0 to 1.0,
where 0 represents complete dissimilarity and 1.0 represents
complete similarity.
There were few cases of high floristic similarity (Figure
10). One was a comparison between the two natural marshes
sampled and another between the Sanlan Juncus marsh and the
Four Corners mulched plot, both of which compare samples of
with low species richness. The other cases of high floristic
similarity are within-site sample comparisons, one from
Clearsprings and one from Fort Green.
The Clearsprings samples had the largest number of
species and had moderately high to high within-site floristic
similarity. The species assemblage at Clearsprings had
several unique or less frequently encountered species, includ
ing Aster subulata. Baccharis halimifolia. Eclipta alba. and
Ptilimnium capillaceum. The samples from Fort Green also
exhibited moderately high to high within-site floristic
similarity, largely due to three species (soft rush, Ludwiqia
virgata, and a species of Cvperus).
Many comparisons of low to moderate similarity are noted,
primarily because of the near ubiquity of soft rush and
smartweed in all samples (Figure 10).
Species diversity. Species richness and species
diversity were compiled from data from this study and from
Lake Kanapaha (Myers, 1983) (Table 4). Diversity was


3
(Humphrey et al., 1978; Schnoes and Humphrey, 1987; Wallace,
1988) and wetland sites (Clewell, 1981; Rushton, 1983, 1988).
Vegetation studies of phosphate clay settling ponds reported
an initial cover of cattails (Tvpha sp.) and water hyacinths
(Eichhornia crassipes) followed by primrose-willow (Ludwiaia
peruviana) and willow (Salix caroliniana). Wax-myrtle (Mvrica
cerfera) and vines dominated sites as they continued to dry
(Zellars-Williams and Conservation Consultants, 1980; King et
al. 1980; Rushton, 1983). These studies generally describe
an arrested succession in which the initial species
composition of primary invading species is perpetuated. In
contrast, other studies (Kangas 1979, 1983) have described
older sites where succession did not appear to be arrested or
inhibited. In cases with a nearby seed source, sites were
invaded by hardwood species such as red maple (Acer rubrum),
laurel oak (Ouercus laurifolia), and live oak (Ouercus
virginiana) (Zellars-Williams and Conservation Consultants,
1980; Rushton, 1983).
Background and Concepts
Succession Theory
Clements (1916) described succession as a universal,
orderly process of progressive change. He asserted that the
community developed from diverse pioneer stages to converge
on a single, stable, mesophytic community (monoclimax) under


118
Table 16. Results of paired-difference comparisons between
mound and non-mound soils for selected chemical parameters
from Tiger Bay (1 year-old), Fort Green (2 year-old) and
Clearsprings (5 year-old) reclamation areas.
Difference
(Mound -
Non-mound)
Site
Age
(Years) Mean Error
Range P
Calcium
1
315.0
227.4
- 250 to 1250
NS
(mg/X)
2
-198.5
343.5
-1370 to 970
NS
5
-93.3
366.7
-510 to 340
NS
Magnesium
1
108.3
121.8
-90 to 700
NS
(mg/X)
2
-38.3
51.6
-260 to 90
NS
5
48.3
15.1
-10 to 100
.05
Manganese
1
1.2
0.79
0.0 to 5.0
NS
(mg/X)
2
0.0
0.26
- 1.0 to 1.0
NS
5
2.5
0.5
2.0 to 5.0
.01
Potassium
1
94.2
25.8
37 to 206
.05
(mg/X)
2
55.5
9.9
29 to 86
.01
5
79.3
14.5
52 to 141
.01
Sodium
1
28.3
10.7
8 to 72
.01
(mg/X)
2
24.8
9.3
4 to 54
.01
5
7.0
2.0
0 to 14
.05
Nitrogen
1
1902
288
1260 to 3220
.01
(mg/X)
2
764
188
350 to 1575
.01
5
1843
378
210 to 2730
.01
Organic
1
0.51
0.18
.06 to 1.37
.05
Matter
2
0.27
0.15
-.39 to 0.65
.2
(%)
5
0.15
0.09
-.13 to 0.52
.2
PH
1
0.73
1.212
.26 to 1.56
NS
2
-0.33
1.326
-.93 to 0.56
NS
5
0.11
0.561
-.21 to 1.12
NS


155
Succession
The preceding discussion of the field test results
effectively illustrates the uncertainties and contradictions
impeding interpretation of ecosystem development. The three
paradigms of succession (relay floristics, initial floristics,
and inhibition) are too rigidly and narrowly constructed. The
field tests used in this study, which followed the
experimental design of Connell and Slatyer (1979), assume that
the paradigms are mutually exclusive and that the pattern and
course of succession is determined by only one. It is more
likely that all three operate at some level during the course
of succession. Hils and Vankat (1982) reached the same
conclusion, finding that more than one model of succession may
apply in one old-field at the same time reflecting the spatial
heterogeneity of the old-field community.
Connell and Slatyer's (1977) approach appears to address
only secondary succession. By omitting primary succession
only implicitly, they further cloud the issue. As noted
above, temporal factors need to be considered, and it is also
likely that different paradigms may be appropriate at
different stages of development.
Role of fauna in succession. The Connell and Slatyer
(1977) approach is also deficient in not considering the role
of micro- and macrofauna in ecosystem development. Animals
serve such functions in the community as seed dispersal, and


76
higher elevation (36.45 m msl). Four of the transects ended
at approximately the same elevation of 3 6.60 m msl. The
remaining two transects (130 and 139) ended at approximately
36.80 m msl.
The daily basin water levels for the period August 1982
to December 1985 were used to generate a depth exceedance
relationship (Figure 14) showing percent of the time a given
elevation was inundated. The graph shows a 1.2 m variation
in water level during the study period; elevations below 35.51
m msl were inundated 100 percent of the time and areas above
36.73 m msl were never inundated. The curve slopes gently in
the 80 to 100 percent inundation, range which covers a
relatively broad range of elevations from 35.51 to 36.33 m
msl. The 70 to 80 percent inundation zone covers a relatively
narrower elevation range (36.33 to 36.45 m msl). The slope
of the depth exceedance curve is fairly steep in the 0 to 70
percent inundation range (elevation 36.33 to 36.73 m msl) then
flattens at the maximum inundation of 36.73 m msl.
Emergent Macrophytes. The changes in cover of
pickerelweed (Ppntederia cordata) and cattail (Tvpha latifolia
and T. dominqensis) on each of the six transects through each
of the eight sampling periods were summarized from the line-
intercept data. Pickerelweed and cattail were used because
each was initially the dominant perennial emergent macrophyte
in the mucked and unmucked zones, respectively. This


31
observation led to the hypothesis that mound soils were more
fertile because of the ants.
Third, it was noted that overburden soils high in clay
formed surface crusts that inhibited water infiltration, but
mound building and tunneling by ants broke the surface crust
and maintained the soil in a more friable condition.
Fire ants are omnivorous scavengers who forage the
landscape, gathering food materials and returning with them
to the mound. This activity concentrates otherwise dilute
nutrient materials, which may be one of the primary functions
of ants in the ecosystem. If ant mounds represent a localized
concentration of nutrients in the form of insect parts, plant
parts, feces, and waste products, then they are also likely
to be foci of microbial activity mineralizing organically
bound nutrients. The ant colony and mound system may recycle
materials that are scarce in the developing ecosystem.
Mound-building ants may alter the soil profile and
influence particle size distribution, bulk density, porosity,
and infiltration capacity. These soil alterations may affect
primary production.
Relationships are shown in diagrammatic form. Arrows on
a causal loop diagram of the ant model indicate pathways of
influence (Figure 4) A "+" used at an arrowhead indicates
an increase in the adjacent item. For example, a larger
concentration of food materials in the mound leads to a
higher level of microbial decomposers. A indicates a


75
37.0
1 36.5
E
36.0
35.5
37.0
| 36.5
E
35.5
s/
TF
ANSEC
T 115
30 50 90 120 150 180
i(m)
A
a y
y
TF
ANSEC
)T 125
I l
30 60 90 120 150 180
0 30 60 90 120 150 180
Transact DWanca (m)
Figure 13. Elevation profiles of marsh transects 115. 125,
and 130.


133
allogenic forces (the environmental sieve) on the wetland
vegetation. The model emphasizes, as did Gleason and others
(Drury and Nisbet, 1973; White, 1979), that the key to
vegetation dynamics lies in understanding the life history
characteristics of the species constituting the vegetation.
This suggests that succession can be explained entirely as a
disintegrated individualistic phenomenon.
A conceptual model with a focus limited to allogenic
factors and the life history strategies of the individual
species ignores many of the biological properties of the
wetland community. The model's focus on secondary succession
assumes that the community structure is already in place and
does not account for the processes that build that structure.
The model does not explicitly recognize the autogenic
processes and, therefore, lacks the feedback to show how the
environmental sieve can itself be modified to some extent by
the wetland vegetation.
An example of autogenic feedback is the formation of an
organic soil through peat deposition. Wetland succession can
occur on mineral soil, depending on the site conditions and
the nature of the disturbance that initiated the succession.
Certainly, in the case of unreclaimed mined land, the wetland
community will develop on mineral substrate. Through time,
an organic substrate accumulates as litterfall exceeds
decomposition. The accumulated organic sediments raise the
effective ground level in the wetland, thus altering the


74
O 30 60 90 120 150 180
Trancl Distance (m)
0 30 60 90 120 150 180
Transact Distance (m)
37.0
1 365
E,
| 36 0
35.5
MuckTre
itmentZc
me
TF
ANSEC
T 139
1
0 30 60 90 120 150 180
i(m)
Figure 12. Elevation profiles of marsh transects 97,
139 with muck treatment zones indicated.
105 and


127
study show that the plant communities that developed in the
two treatment areas differed in species composition and that
these differences remained stable through at least the first
four growing seasons. This stability suggests that initially
established vegetation can occupy the available open space and
resist invasion or encroachment by other taxa. Dense stands
of pickerelweed established in the muck treatment areas
remained stable and were not invaded by cattail, primrose
willow, or other aggressive weedy species typically associated
with arrested succession on unreclaimed phosphate-mined lands.
Similarly, dense stands of cattail have also remained stable,
resisting invasion. In contrast, open stands of cattail in
other portions of the wetland were invaded by bulrush in 1984
and 1985. Recent studies show that dense stands of bulrush
have since developed in these areas, competitively displacing
the cattail (G.R. Best, personal communication, 1988) .
Bulrush showed an ability for widespread dispersal of
waterborne seeds, colonization, and rapid vegetative
expansion.
The marsh transect studies indicated that the initial
floristic composition, sensu Egler, largely determined the
species composition within the marsh, and that in the absence
of disturbance, the initial vegetation pattern and species
composition are maintained for some time, possibly even long
term.


158
to the treatment levels selected and not to a population
of possible levels.
3. A limited number of tree species was used in the tests,
and although the responses of the species differ, results
are interpreted in terms of a whole forest.
4. Results are from a single set of tests carried out on one
soil type at one site, so conclusions about the process
of forest development must be couched in appropriate
scope and scale.
6. Allelopathic effects of herbaceous species on each other
and on woody plants may be important and were not
investigated.
7. The weeding treatment may provide indirect benefits by
disturbing the soil, increasing the rate of water
infiltration by breaking up soil crusts commonly found
on exposed overburden soils.
8. In the seeded plots it was easier to locate and measure
seedlings in the seed plots receiving the weeding
treatment. It is possible that some small seedlings were
overlooked in the other treatment plots. So, then
germination results would be biased in favor of the
weeded treatment.
Mound-Building Ants
Mound Survey
The mound densities measured in the survey ranged from
560/ha to 2,100/ha on 1 to 5-year old sites. Kangas (1983)
found ant mound density increased dramatically over the first
10 years on unreclaimed phosphate-mined land, from 2,000/ha
at 1 year to over 8,000/ha at a 10-year old site.
Adams et al. (1978) estimated fire ant mound density in
agricultural fields in Brunswick County, North Carolina, at
141 mature mounds per hectare. Baroni-Urbani and Kannowski


18
when earthworms were removed (Witkamp, 1971). Earthworms
stimulated the growth of potted barley seedlings, possibly by
increases in vitamin B12 (Atlavinyte and Dacinlyte, 1969).
Dung beetle activity was found to be almost as effective as
mechanical mixing in enabling plants to benefit from the
nutrient storages in dung (Bornemissza and Williams, 1970).
Leaf cutter ants (genus Atta) reduced primary productivity by
reducing leaf area, but more than made up for that loss by
returning materials to the soil (Lugo et al., 1973).
Mound-building ants can produce localized concentrations
of organic matter and nutrients, resulting in changes in
densities of bacteria, fungi, and plants (Czerwinski et al.,
1971). They can affect the physical and chemical aspects of
soil as well as the distribution of plants, bacteria, and
fungi, and are important in making channels and burrows. Hopp
and Slater (1948) felt ants could be as effective as
earthworms in creating conditions for improved plant growth,
while Thorpe (1949) indicated that ants may produce greater
effects than earthworms. Shrikhande and Pathak (1948)
reported that ants increased the organic matter content of
soils second only to earthworms.
Numerous studies have shown chemical differences between
mound and nearby non-mound soils, with evidence of higher
levels of exchangeable cations, micronutrients, nitrogen,
phosphorus, and organic matter, as well as differences in pH
and conductivity (Czerwinski et al., 1969, 1971; Gentry and


159
(1974) estimated the fire ant mound density of a Louisiana
pasture at 96/ha. The relatively lower mound densities in
these two studies may be a result of site-specific factors,
but are more likely due to the authors* focus on large mature
mounds.
Kangas (1983) also noted a general increase in size of
ant nests with increasing site age up to a point and then a
later decline. For example, few ants were seen on a 50-year-
old site. This observation may indicate a change or
succession in the ant fauna through time as the vegetation,
light levels, food quality, and physical and chemical
character of the soil profile change.
Ant Mound Roles
Soil development. Mound building affects soil bulk
density, particle size distribution, and the amount and
distribution of pore space. The bulk density of soils from
the 2-year old site showed mound values to be approximately
80 percent of the non-mound values, 1.19 g/cm3 versus 1.74
g/cm3. Wali and Kannowski (1975) measured the bulk density on
mounds of seven species of ants on prairies in northeastern
North Dakota and found the values to lie in a narrow range of
0.64 to 0.75 g/cm3 in comparison to 1.15 g/cm3 for non-mound
prairie soil. Levan and Stone (1983) measured the bulk
density of a black meadow ant (Formica fusca) mound as 0.51
g/cm3.


Pood
Upland
Figure 7. Fort Green wetland reclamation area showing marsh transect locations
approximate vegetation zones, and muck treatment zones.


184
. 1983. Riverine forest restoration efforts on
reclaimed mines at Brewster Phosphates, Central Florida.
In D. J. Robertson (ed.), Symposium on Reclamation and the
Phosphate Industry. Florida Institute of Phosphate
Research, Bartow, Florida.
Connell, J. H. and R. 0. Slatyer. 1977. Mechanisms of
succession in natural communities and their role in
community stability and organization. Am. Nat.
111:1119-1144.
Cowles, H. C. 1899. The ecological relations of the vegetation
of the sand dunes of Lake Michigan. Bot. Gaz. 27:95-117.
Crane, D. 1972. Invisible Colleges: Diffusion of Knowledge
in Scientific Communities. University of Chicago Press,
Chicago. 425 pp.
Crocker, R. L. and J. Major. 1955. Soil development in
relation to vegetation and surface age at Glacier Bay,
Alaska. J. Ecol. 43:427-448.
Culver, D. C., and A. J. Beattie. 1983. Effects of ant mounds
on soil chemistry and vegetation patterns in a Colorado
montane meadow. Ecol. 64:485-492.
Czerwinski, Z. 1971. The influence of ant hills on meadow
soils. Pedobiologia 11:277-285.
Czerwinski, Z., H. Jakubczyk, and J. Petal. 1969. The
influence of the ants of the genus Myrmica on the physico
chemical and microbiological properties of soil within the
compass of ant hills in Stzeleckie meadows. Polish Journ.
of Soil Science 3:51-58
Dixon, A. F. G. 1971. The role of aphids in wood formation.
I. The effect of the sycamore aphid, Drepanosiphum
platanoides (Schr.) (Aphididae) on the growth of sycamore,
Acer psuedoplatanus (L.). J. Appl. Ecol. 8:165-179.
Drury, W. H. and I. C. Nisbet. 1971. Interrelations between
developmental models in geomorphology, plant ecology, and
animal ecology. Gen. Syst. 16:57-68.
. 1973. Succession. J. Arnold
Arboretum. 54:331-368.
Edwards, W. M., R. R. van der Ploeg, and W. Ehlers. 1979. A
numerical study of noncapillary-sized pores upon
infiltration. Soil Sci. Soc. Amer. Journ. 43:851-856.


178
systems. The reclamation design principle then is to create
wetland and upland systems that contain (1) a variety of
habitat conditions with a variety of soil types and soil
moisture conditions, and some variation in microtopography;
(2) a diverse assemblage of plants with many representatives
of all life history strategies; (3) habitat conditions needed
to enhance the formation of a diverse soil fauna; and (4)
habitat conditions needed to enhance the use of the site by
a diverse assemblage of wildlife. Once the reclamation effort
has provided a diverse array of choices, then the system can
"choose" the actual species composition of the community.


INTRODUCTION
The pattern and process of ecosystem development, usually
called succession, are a main focus of the science of ecology.
The paradigms used to understand succession are still in
controversy, and the pattern and process of ecosystem
development are still much debated. A clear understanding of
succession provides an opportunity for forming rational and
cost-effective land reclamation techniques and policies that
will enhance the successional process on disturbed lands. It
is not possible to predict the long-term development of
created and restored ecosystems without a clear understanding
of the natural processes of ecosystem development.
Unfortunately, the ecological literature remains divided on
the fundamentals of succession, especially the interactions
between early colonizing plant species and late successional
species and the role of non-trophic interactions between
producers and consumers.
The establishment of vegetation is one of the first
stages of primary succession on an abiotic substrate, whether
the succession results from geologic uplift, glacial retreat,
volcanic lava flow, landslide, or strip-mining. The post
mining landscape is a relatively simple ecosystem of few
1


40
created to encourage emergent plants, store water onsite, and
create fish and wildlife habitat. Test plantings of 15
different tree species, planted as bare root seedlings were
done in 2 6 plots with 400 trees per plot. Freshwater
macrophytes were also planted in the basins.
Fort Green Wetland Demonstration Project. This wetland
project is part of a 148-hectare reclamation project carried
out by Agrico Mining Company at its Fort Green Mine in
southwestern Polk County (Figure 6) The site, which was
mined in 1978 and 1979, was recontoured to create 61 ha of
wetlands and 87 ha of uplands (Figure 7) The reclamation
began in 1981 and was completed by May 1982. The project
sought to create open water, freshwater marsh, freshwater
swamp, and upland habitat.
The site is gently sloping with a range of 40.23 m down
to 35.40 m mean sea level (msl) in the wetland basin. The
wetland basin receives runoff and baseflow from the
surrounding uplands. The basin has a highwater discharge to
the adjacent floodplain of Payne Creek when the surface water
elevation reaches approximately 36.58 m msl. Within the
wetland basin are several deep holes that serve as deep water
habitat and aquatic refuge during times of drought. These
deep pools have spot elevations ranging from 31.85 to 35.36
m msl.
The donor muck was transported from a nearby donor marsh
and spread in the littoral zone with depth varying from 2.5


136
or conceptual model of wetland succession must recognize both
these forces and the interplay or feedback between them. An
alternative formulation of the van der Valk model (Figure 16)
can be developed to include other system components, such as
the wetland substrate and consumers, and to show the feedback
relationships between the components and the environmental
sieve.
With regard to the competing paradigms (initial
floristics, inhibition, relay floristics, coevolution, and
self-organization), this work and other studies indicate that
all are operating at some time during wetland succession. The
formation of plant communities from seed/propagule banks
following disturbance is a case of initial floristics. Bersok
(1986) found no significant difference between tree seedling
success in cleared plots versus cattail plots. Pickerelweed
and cattail stands that remain stable in the absence of
disturbance and support to the inhibition model. Coevolution
and relay floristics are important in wetland tree dispersal;
bird and mammal species involved in seed dispersal must have
their habitat requirements satisfied before they will use the
site. Seed/propagule banks and accumulated belowground
structures (e.g., roots, rhizomes) provide a storage of
"choices" for all environmental contingencies, thus
supporting the self-organization model.




128
Patch dynamics. The use of permanent transects allowed the
fate of individual patches to be tracked through time. The
large stands of cattail and pickerelweed developed from
individual plants or patches that gradually coalesced into
larger units. A similar pattern of plant establishment can
occur on abandoned coal-mined land, as patches or islands that
grew individually and eventually coalesced (Game et al.,
1982) Some patches disappear and are replaced by an
individual or group of individuals of another species. This
suggests that a patch has to be of some critical size before
it can be successfully established, and that the "critical"
patch size probably changes as a function of the surrounding
vegetation and the growth rate of the species.
The vegetation pattern composition and species
composition of a marsh community appear to be largely a
function of the propagules available and the prevailing
environmental conditions which supports the seed
bank/environmental filter model described by van der Valk
(1981). The community responds to an array of environmental
factors that affect its composition. Major environmental
factors affecting wetland communities include depth, duration,
and seasonal pattern of flooding, and fire.
Effect of Herbivorv. Herbivory can also be an important
factor regulating species composition and productivity in
wetlands. Feral hogs are common in the Payne Creek floodplain


180
4. Under appropriate conditions, even slow-dispersing marsh
species are able to become established and occupy the
available space. Once the available space is filled,
opportunity for invasion, even by aggressive weedy
species like cattail, is limited.
5. Marsh studies at the Fort Green site have shown the value
of documenting specific site histories, beginning if
possible with an unvegetated substrate. Long-term
studies provide the best view of ecosystem development.
6. The Gleasonian model proposed by van der Valk (1981)
appears to have merit as a partial descriptive paradigm
of wetland species composition in secondary succession.
It does not recognize the autogenic processes that can
feedback to and influence the "environmental sieve."
7. Evidence was found in the upland tree seedling plots to
support the operation of all paradigms: inhibition,
initial floristics, relay floristics, coevolution, and
self-organization. A unified paradigm that the ideas of
all five paradigms will provide an eclectic resolution
to the controversy.
8. Field studies show that mound-building ants can influence
soil structure, runoff and soil infiltration, nutrient
cycling, plant growth, and plant species distribution.
Similar effects have been documented for the soil fauna
in other ecosystems.
The arrested succession observed by many researchers on
9.


62
that the species richness and size of the seed bank appear to
decrease as the water depth increases in the Sacciolepis
zone-Amaranthus zone-Echinochloa zone-Pond zone (Table 4).
For the wetland samples cited from outside Florida, the
densities range from 6,000 to 40,000/m2, and for the three
natural systems sampled in this study, the range of densities
is 8,000 to 72,000/m2. The two marsh samples (Four Corners
natural marsh and pasture marsh) had densities of 41,000/m2
and 72,500/m2, respectively.
The unreclaimed wetland sampled, the Sanlan marsh, had
densities of 12,000/m2 and 62,000/m2 from the Eichhornia and
Juncus marshes, respectively. As with the Kanapaha samples,
seed bank size apparently decreases with depth (water depth
is more than a meter in the Eichhornia marsh). The Sanlan
samples, especially the Juncus-Polvqonum zone with 62,000/m2,
fall in the range of the natural wetlands already discussed,
thus representing some of the higher densities encountered.
This indicates that sizeable seed banks can develop in the
absence of any reclamation efforts in post-mining wetlands.
Wetland samples from reclaimed mine lands had a range of
1,800 to 33,000/m2, which is low to moderate by comparison to
natural wetland systems. Samples from the three basins at
Clearsprings ranged from 7,000 to 11,000/m2; at the Four
Corners project, the range was 2,200 to 33,000/m2. More
specifically, the treated plots had densities well within the
range of the natural systems: topsoiled (peat) marsh plot


Pontederia cordata
FaM 1962
Spring 1963
100
Summarises |
o
!00
FaM 1963
Spring 1964
o
10
I.
/ 100
o
0
Summer 1964
FaM 1964
100
Summer1965 k
J .
i r-
i 1
15 30 45 60 75 90
Transect Distance (m)
Typha latifolia
Transect 130
1 1 1 1
n n [
1
1 i i
n moli
D C=L
O
0 15 30 45 60 75 90
Transect Distance (m)
oo
en


174
Relay Floristics
In a few cases relay floristics has been demonstrated.
The results from the Gardinier tree plots showed that during
primary succession areas subject to erosion and/or unstable
substrates require a cover crop or nurse crop of early
successional species in order to stabilize the substrate
before later successional species can become established. In
most areas, natural colonization by rapidly dispersing species
will typically provide a cover crop within the first growing
season. In areas subject to erosion, reclamation efforts
should enhance and accelerate establishment of a cover crop.
Seeding is one commonly used method. Spreading of
topsoil/muck from donor upland/wetland sites is another
method.
Coevolution
Within the constraints of resource supply or other
environmental factors the autogenic, biological system is
characterized by strong positive feedbacks among its
components. Classic mutualisms exist between plants and
mycorrhizal fungi, pollinators, and seed dispersers to name
a few examples, but there are also the extended mutualisms
that exist between plants and their rhizosphere, as well as
the interactions that may not fit the standard definition of
mutualism at all, but nonetheless are characterized by strong


Figure 10. Summary matrix of floristic similarity between seed bank samples.


172
plants or patches that gradually coalesced into larger units.
A patch has to be of some critical size before it can be
successfully established, and that the "critical" patch size
probably changes as a function of the surrounding vegetation,
the amount of open space available, and the growth rate of the
species. On upland sites, woody species characteristic of
later successional stages can be easily planted or seeded
during early revegetation efforts.
In some cases an arrested successional stage may be
desireable, such as along utility line rights-of-way. If so,
then revegetation efforts can be targeted at enhancing the
establishment of those species capable of arresting succession
on disturbed lands. The use of grazing, mowing, and periodic
burning can also be helpful tools for arresting succession.
For instance, fire may be needed for preventing the
encroachment of woody species into marsh systems.
Initial Floristics
Egler's initial floristic hypothesis portrays old-field
succession as a seed bank response to a change in
environmental conditions. Studies in this dissertation show
that initial floristics is also an important factor during
primary succession on upland and wetland sites. The initial
floristic composition is an important determinant of the type
of vegetation that develops following disturbance. The
vegetation pattern, and species composition of the marsh


146
treatment. The means for the other three treatments were not
significantly different. The oak results may be similar to
those of hickory, suggesting a causal relationship between
large food reserves in the seed and less treatment-related
mortality in the first growing season.
Height Growth
Seed plots. When seedling height data are summed for all
species, significantly different and greater height growth
appear to be a result of the weeding treatment. This result
seems clearcut and profound, as seedlings in the multi-species
plots grew significantly better under the weeding treatment,
and relay floristics and initial floristics models must
therefore be rejected in favor of the inhibition model.
Closer examination, however, indicates the results may
actually support more than one model.
When the growth data are summed over all species, the
resultant data set is heavily biased toward the oak; both
because the two oak species were combined to avoid skewing
results from misidentification of individual seedlings and
because oak had a higher level of germination and survival
than the other taxa. Oak seedlings made up 74 percent of all
seedlings found, whereas cabbage palm comprised 12 percent,
hickory 7 percent, and sugarberry and sweetgum 5 and 2
percent, respectively. It is therefore not surprising that
the height growth analysis for oak has exactly the same


6
with the discipline of population ecology. Dichotomies still
center on questions of holism versus reductionism, the
evolutionary unity of communities, and whether ecosystems
possess emergent properties.
E.P. Odum (1969) provided a modern ecosystem
reformulation of Clementsian succession. Odum noted the
similarity of succession to the development of individual
organisms and converged with Clements' description of
succession as an orderly process that is reasonably
directional and therefore predictable, resulting from
modification of the physical environment by the community
(autogenic) and culminating in a stabilized (climax, mature)
ecosystem with homeostatic properties.
Confusion developed when some ecologists described the
ecosystem as having an evolutionary unity. Patten (1975)
called the ecosystem a "coevolutionary unit." Webster et al.
(1974) stated that a basic assumption of ecosystem analysis
is that ecosystems are units of selection and evolve from
systems of lower selective value to ones of higher selective
value that optimize utilization of essential resources. Other
ecologists did not view communities or ecosystems as
evolutionary units because inheritance of genes is passed
separately by the many species.
H.T. Odum (1983) describes succession as a self
organizing process by which ecosystems develop structure and
processes from the available choices supplied by seeding. The


Ponlederia cordata
Transact Distance (m)
Typha latttoMa
Transact 125
03
4s


156
pollination. This study addresses the effect of mound
building ants in ecosystem development on mined lands; the
role of earthworms in soil turnover and nutrient cycling
provides another well-documented example of the influence of
animals on vegetation development.
Seed dispersal by animals, especially birds, is a
potentially very important means for trees to invade disturbed
areas. If the developing community provides the proper
habitat requirements for seed-dispersing agents, then the
invasion by later successional species may proceed much
faster. Evidence of tree seed dispersal by birds can be seen
in the woody flora found along almost any fence row, where
seedlings of berry-producing species like black cherry (Prunus
sertina), hercules-club (Zanthoxvlum clava-heuculis), and
sugarberry are quite common. In many of the central Florida
citrus groves abandoned after the severe winter freeze of
1983, laurel oak and black cherry seedlings invaded within the
first year or two, typically found beneath the standing-dead
citrus trees. This invasion pattern was a result of the perch
sites provided by the dead citrus trees and used by the seed
dispersing birds. Field studies by McClanahan (1984) and
Wolf (1986) indicate that seed dispersal to a large degree
determines the rate at which forested ecosystems recover from
catastrophic disturbances such as strip-mining. For animal-
dispersed seeds, site attractiveness appeared to be more
important than distance.


Cumulative Number of Seeds Germinated
Motete Oc lobar
o
O
E
3
E
3
o
200-1
too -
Carya globro
200-,
Magnolia grandiflora
October
March
too-
March
OcMhar
Dtd Individuals
Uv Individual
200
J9
m
a
* 100
o
Liquidombar
slyraciflua
March
October
200 n
a
a
1
3
X
- IOO-
3
c
Sobol palme Mo
October
VO
m


38
South Fort Meade Mine tract. The vegetation within the marsh
was dominated by softrush (Juncus effusus), pickerelweed
(Pontederia cordata), Sagittaria lancifolia. and smartweed
(Polygonum punctatum). The marsh was selected as typical of
the freshwater marshes within the study area, most of which
are subject to grazing.
Peace River Bavhead. This bay swamp is located on a
seepage slope draining to the Peace River on Mobil's South
Fort Meade Mine tract. The swamp had an overstory of sweetbay
magnolia (Magnolia virginiana), red bay (Persea palustris),
and dahoon holly (Ilex cassine). The groundcover consisted
primarily of lizard's-tail (Saururus cernuus) The substrate
consisted of a layer of finely decomposed muck overlying
fibrous peat. The depth of the organic soil averaged
approximately 1 m.
Sanlan Marsh. This marsh developed on an unreclaimed
clay settling area that was mined in the early 1950's. The
site was selected because it was one of the few old,
unreclaimed clay settling ponds that was not dominated by
cattail, primrose-willow, or willow.
Four Corners Demonstration Project. W.R. Grace Company
initiated a wetland reclamation demonstration project at its
Four Corners Mine site in 1979. Four 0.16-ha depressions were
excavated to a maximum depth of 1.2 m in a pine-palmetto
flatwoods adjacent to Alderman Creek in 1978. The area was
not mined, but overburden was removed to a depth below the


24
species. Slower growing late successional species can only
become established when the early colonizers have been killed
or disturbed.
Relay floristics. Late successional species are unable
to become established on bare ground; they arrive and become
established only after some critical level of development has
been reached (Figure 3d) Late successional species gradually
displace the early colonizing species. Competition for light
results in poor growth and reproduction by early colonizing
species, when later successional species are established.
Coevolution. An expanded version of the relay floristics
model that also recognizes a long-term relationship between
species (e.g., feedback relationships between and among
trophic levels) (Figure 3e).
Self-organization. Producers, consumers, and decomposers
are linked in a dynamic feedback network in which each trophic
level is composed potentially of many species. Actual species
composition of the community is a function of the system's
self-organizing choices, which reinforce those combinations
that optimize the use of resources and maximize productivity
(Figure 3f) Controls and reinforcement are shown from
animals and larger scale phenomena of the surrounding system.
Changes in Paradigms
The continuing contradictions about succession after many
decades of study suggest that more may be involved than a


164
Rogers and Levigne (1974), and Wali and Kannowski (1975). The
statistically significant, higher levels of potassium mound
soils are evidence of nutrient concentration by animals.
Potassium may also come indirectly from phloem exudates via
aphids (Levan and Stone, 1983), on which fire ants are known
to feed (Lofgren et al., 1975).
Elevated sodium levels in mound soils are more
perplexing. Sodium is a minor essential nutrient for animals
but not for plants. It is also a readily solubilized ion from
a variety of inorganic salts. It is possible that elevated
levels of potassium and sodium may be the result of
differences in evaporation rates between mound and non-mound
soils. The lower bulk density and greater pore space of mound
soils may facilitate evaporation of soil water, resulting in
salt deposition. It is also possible that elevated levels of
potassium and sodium in mound soils are caused by microbial
decomposition of the organic matter in the mounds. The
evaporation hypothesis remains one possible explanation of the
elevated cation levels, but elevated organic matter and
nitrogen levels provide additional support for the biological
concentration argument.
Lack of statistically significant differences for calcium
and magnesium is not surprising, as overburden soils
containing limestone and dolomite typically have high
concentrations of these cations. Concentrations of calcium
and magnesium ranged from several hundred to several thousand


I sincerely thank my wife, Buffy, for her eternal patience
and support during this degree.
Charlie and Sam for making life
Finally, I thank my two sons
bearable during the "crunch."
iii


112
(Table 12a). In both cases, the F-value was significant
(p =.0001) and the mean height growth for the weeded
treatment was significantly different and higher than the
other three treatment means. There were no significant
differences among the means for the natural colonizer,
enhanced legume, and enhanced colonizer treatments. Assigning
the height growth data by individual species reveals an
interesting trend. Generally, the oak results mimicked the
results from the combined species data, while hickory,
sugarberry, sweetgum, cabbage palm, and magnolia all had
similar results as a group that were quite different from oak.
As in the case with height data summed over species, the
oak data had a highly significant F-value for both ANOVA
regimes. The weeded treatment mean was found to be
significantly different from and higher than the other three
treatment means, which were not significantly different from
each other (Table 12e) For the most part, the growth
response of the other four species (hickory, sugarberry,
sweetgum, and cabbage palm) were similar. In all cases, no
statistically significant differences were seen among the
treatment means (Tables 12b, 12c, 12d, and 12f).
Height Growth in Transplant Plots
The three species (sweetgum, live oak, and cabbage palm)
were first treated separately in the analysis under the
assumption that the 1-m spacing between seedlings would


113
prevent any interaction between species. Analysis was also
performed summing growth data for all three species together.
The ANOVA of the height growth data for each of the three
species showed a significant F value (p < .05) (Table 13),
indicating that at least one of the treatment means was
significantly different from the rest. Duncan's multiple
range test was used to determine which treatment means were
significantly different (Table 13).
For sweetgum seedlings, the mean height growth for the
weeded treatment was significantly different and higher than
the mean height growth of the other three treatments, and
there was no significant difference among the means for the
natural colonize, enhanced colonizer, and enhanced legume
treatments.
The mean height change for the live oak seedlings was
also significantly different for the weeded treatment. The
live oak seedlings in the weeded plots had a higher mean
growth change over the first growing season. The analysis
again showed no significant difference among means in the
other three treatments.
The Duncan's multiple range test for the cabbage palm
data yielded different results. Weeded, enhanced legume, and
natural colonizer treatments were not significantly different
from each other and neither were the natural and enhanced
colonizer treatments. The weeded and legume treatment means


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151
areas with annuals. Using the decision criteria of Connell
and Slatyer (1977), this experiment supports the inhibition
model.
Pinder (1974) studied the effects of the presence of the
dominant grasses on the productivity of subordinate forbs
within a perennial-grass, old-field community. He found that
removing the dominants increased the net productivity of
almost all subordinate species.
Hils and Vankat (1983) used the species-removal approach
to test Connell and Slatyer's (1977) models in the first year
of old-field succession. Their experimental treatments
included removal of annuals, annuals and biennials, and
perennials. Results from the first growing season favored
acceptance of the initial floristics model, but the authors
cautioned that more than one model of succession may apply in
the same field at the same time, reflecting the spatial
heterogeneity of the old-field community. The same old-field
plots were further studied by Zimmerman and Vankat (1984).
The species-removal treatments were maintained in the second
year and the developing community was studied for the next
three years. The initial floristics model was still supported
at the end of 5 years because the authors found no
statistically significant differences between the biomass of
perennials grown with annuals and biennials and the biomass
of those grown alone. Succession resulted in the development
of nearly identical communities in the two treatments. The


ECOLOGICAL PARADIGMS, SPECIES INTERACTIONS, AND
PRIMARY SUCCESSION ON PHOSPHATE-MINED LAND
by
WILLIAM JAMES DUNN
A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMEMT
OF THE REQUIREMENTS FOR THE DEGREE OF
DOCTOR OF PHILOSOPHY
UNIVERSITY OF FLORIDA
1989

ACKNOWLEDGMENTS
I thank my faculty committee members Dr. G. Ronnie Best,
Dr. H. T. Odum, Dr. Clay Montague, Dr. Steve Humphrey, and
Dr. Warren Viessman for their guidance.
The research was supported by Florida Institute of
Phosphate Research grant number 81-03-008, "Enhanced
Ecological Succession Following Phosphate Mining," G. R. Best
and H. T. Odum, principal investigators.
Several mining companies provided support and information.
Marsh studies at Fort Green were in part supported by Agrico
Mining Company. Mobil Chemical Company, International
Minerals and Chemical Company, Gardinier Phosphate Company,
and W. R. Grace and Company provided access to study sites.
Special thanks go to those who assisted with field work,
Pete Wallace, Mel Rector, Alfonso Hernandez, Juan Hernandez,
Bob Tighe, Jim Feiertag, and Tim King. The late Bill Coggins
ran all the SAS analyses. Dr. Ron Myers allowed the use of
unpublished data on seed banks at Lake Kanapaha.
Marla Mittan helped with technical editing. I wish to
thank CH2M HILL for making its resources available during the
final phases of this dissertation.
ii

I sincerely thank my wife, Buffy, for her eternal patience
and support during this degree.
Charlie and Sam for making life
Finally, I thank my two sons
bearable during the "crunch."
iii

TABLE OF CONTENTS
ACKNOWLEDGMENTS
ABSTRACT vi
INTRODUCTION 1
Previous Studies of Succession on Mined Land 2
Background and Concepts 3
Succession Theory 3
Wetland Succession 9
Role of Consumers 13
Competing Paradigms of Succession 20
Initial Floristics 20
Inhibition 20
Relay Floristics 24
Coevolution 24
Self-organization 24
Changes in Paradigms 24
Hypotheses and Objectives 27
Marsh Development 28
Upland Forest Development 29
Mound-building Ants and Ecosystem Development 30
Description of Study Sites 33
METHODS 43
Marsh Development 43
Seed Bank Survey 43
Marsh Transect Study 45
Upland Forest Studies 47
Direct-seeded Plots 50
Seedling Transplant Plots 51
Mound-building Ants and Upland Succession 53
Survey of Mound Density 53
Physical Soil Analyses 53
Chemical Soil Analyses 55
Plant Growth Study 57
Statistical Analysis 58
IV

RESULTS
59
Marsh Development 59
Seed Bank Survey 59
Marsh Transect Study 72
Upland Forest Succession Plots 90
Seed Germination and Survival 90
Height Growth in Seed Plots 105
Height Growth in Transplant Plots 112
Mound-building Ants 114
Mound Survey 114
Plant Growth Study 114
Chemical Soil Analyses 116
Physical Soil Analyses 120
DISCUSSION 124
Marsh Development 124
Seed Bank Formation 124
Formation and Stability of Macrophyte Communities.... 126
Wetland Succession Model 132
Role of Life History Characteristics 132
Importance of Allogenic and Autogenic Factors 132
Eclectic Wetland Succession Paradigm 135
Upland Forest Succession Plots 139
Seed Germination and Survival 139
Height Growth 146
Species Removal 150
Competition 153
Succession 155
Caveats 157
Mound-Building Ants 158
Mound Survey 158
Ant Mound Roles 159
Ant Model 166
Eclectic Synthesis of Paradigms and Implications for
Reclamation Design 168
Inhibition 170
Initial Floristics 172
Relay Floristics 174
Coevolution 174
Self-organization 176
CONCLUSIONS 179
REFERENCES 182
BIOGRAPHICAL SKETCH 193
v

Abstract of Dissertation Presented to the Graduate School
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Doctor of Philosophy
ECOLOGICAL PARADIGMS, SPECIES INTERACTIONS, AND
PRIMARY SUCCESSION ON PHOSPHATE-MINED LANDS
By
WILLIAM JAMES DUNN
May 1989
Chairman: Dr. G. Ronnie Best
Major Department: Environmental Engineering Sciences
Field studies on phosphate-mined lands were undertaken
to evaluate several paradigms for explaining succession,
including inhibition, initial floristics, relay floristics,
coevolution, and self-organization. Primary objects of study
were wetland seed bank formation, formation and stability of
wetland macrophyte communities, interactions between
colonizing species and trees on upland sites, and the role of
mound-building ants in upland succession.
A survey of natural and post-mining wetlands showed seed
banks develop rapidly, but contain only wind-dispersed early
successional species. Late successional marsh species can be
added as an instant seed bank through muck material from a
donor or, in some cases, by planting.
vi

The development of a reclaimed marsh was monitored over
its first four growing seasons. Results showed that while
very different plant communities developed with the
application of muck from a donor marsh as compared to natural
succession, both types of initially established macrophyte
communities remained stable throughout the monitored period.
Upland succession was enhanced with direct seeding and
seedling transplants in four treatments: natural colonization,
enhancement of natural colonizers, enhancement with legumes,
and weeding. Tree seedlings had better height growth in plots
in which the colonizing weeds were removed. Tests indicated
that the five paradigms investigated operated concurrently
during primary succession.
Fire ants (Solenopsis invicta) were the most commonly
observed invertebrate species on mined lands, with well
established populations within the first year after mining.
Mound densities on 1- to 5-year old sites ranged from 560 to
2,000 per hectare. Mound soils had higher concentrations of
sodium, potassium, total nitrogen, and organic matter than
the adjacent non-mound soils. In greenhouse experiments, a
grass and a woody plant exhibited enhanced growth on mound
soils. Water infiltration rates were 5 to 100 times greater
on mound soils than non-mound soils.
The view of the competing paradigms as mutually exclusive
was not supported. A unifying paradigm may be possible from
a more eclectic synthesis of the inhibition, initial
vii

and
self-
floristics, relay floristics,
organization models.
coevolution,
viii

INTRODUCTION
The pattern and process of ecosystem development, usually
called succession, are a main focus of the science of ecology.
The paradigms used to understand succession are still in
controversy, and the pattern and process of ecosystem
development are still much debated. A clear understanding of
succession provides an opportunity for forming rational and
cost-effective land reclamation techniques and policies that
will enhance the successional process on disturbed lands. It
is not possible to predict the long-term development of
created and restored ecosystems without a clear understanding
of the natural processes of ecosystem development.
Unfortunately, the ecological literature remains divided on
the fundamentals of succession, especially the interactions
between early colonizing plant species and late successional
species and the role of non-trophic interactions between
producers and consumers.
The establishment of vegetation is one of the first
stages of primary succession on an abiotic substrate, whether
the succession results from geologic uplift, glacial retreat,
volcanic lava flow, landslide, or strip-mining. The post
mining landscape is a relatively simple ecosystem of few
1

2
species but provides a rich environment for testing paradigms
describing the pattern and process of succession. Detailed
ecological studies of the recovery process on mined lands may
also identify some solutions to existing reclamation problems.
The succession and human-managed reclamation of phosphate-
mined lands in central Florida provides and opportunity to
evaluate successional theory and use the knowledge to
facilitate reclamation. This dissertation examines
successional processes on phosphate-mined lands, especially
marsh development, upland forest development, and the roles
played by seed banks and mound-building ants.
In a few cases an understanding of wetland succession has
been translated into a successful technique for wetland
creation and restoration. In the Tampa Bay area it was
observed that formerly unvegetated intertidal areas were
quickly colonized and stabilized by smooth cordgrass (Spartina
alterniflora) which presumeably helped mangrove seedlings to
become established years later (Lewis 1982). In 15 to 20
years the mangroves eventually shaded out the cordgrass and
became dominant. Lewis developed a technique for establishing
a nurse crop of cordgrass which has since become a common
practice for mangrove establishment.
Previous Studies of Succession on Mined Lands
Many studies of unreclaimed mined lands have documented
the paucity of late successional species on upland sites

3
(Humphrey et al., 1978; Schnoes and Humphrey, 1987; Wallace,
1988) and wetland sites (Clewell, 1981; Rushton, 1983, 1988).
Vegetation studies of phosphate clay settling ponds reported
an initial cover of cattails (Tvpha sp.) and water hyacinths
(Eichhornia crassipes) followed by primrose-willow (Ludwiaia
peruviana) and willow (Salix caroliniana). Wax-myrtle (Mvrica
cerfera) and vines dominated sites as they continued to dry
(Zellars-Williams and Conservation Consultants, 1980; King et
al. 1980; Rushton, 1983). These studies generally describe
an arrested succession in which the initial species
composition of primary invading species is perpetuated. In
contrast, other studies (Kangas 1979, 1983) have described
older sites where succession did not appear to be arrested or
inhibited. In cases with a nearby seed source, sites were
invaded by hardwood species such as red maple (Acer rubrum),
laurel oak (Ouercus laurifolia), and live oak (Ouercus
virginiana) (Zellars-Williams and Conservation Consultants,
1980; Rushton, 1983).
Background and Concepts
Succession Theory
Clements (1916) described succession as a universal,
orderly process of progressive change. He asserted that the
community developed from diverse pioneer stages to converge
on a single, stable, mesophytic community (monoclimax) under

4
the control of the regional climate. He held that in
succession, the community repeated a sequence of stages,
similar to the development of an individual organism from
birth through death, that was an orderly directional process
predictable in its development. As succession proceeded, the
community increasingly controlled its own environment and,
barring disturbance, became a self-perpetuating climax.
Succession occurred as waves of plant populations made
conditions suitable, or "prepared the way," for the next wave
and often to the detriment of their own continued survival.
To other ecologists of the time, the plant community was
less well defined and succession less orderly, directional,
and predictable than Clements suggested. Alternative concepts
of succession voiced by Gleason (1917, 1926, 1939) advocated
an individualistic, population-based approach in which the
plant association is seen as a coincidence rather than an
interdependent entity. The distribution of a particular
species in the landscape depends on its migration
characteristics and environmental requirements, and the plant
community is an artifact solely dependent on the grouping of
species with overlapping environmental requirements. Given
sufficient time, all species had equal access to all sites,
but species were found only on those sites with the
appropriate environmental conditions. According to this
allogenic theory, a particular species grows in the company
of any other species with similar requirements and eventually

5
disappears from areas where environmental conditions are no
longer favorable.
Egler (1954) also found fault with Clements' view of
succession, but stressed the role of autogenic processes in
old-field community succession. He applied the name "relay
floristics" to Clements' sequential appearance and
disappearance of groups of species and posed an alternative
mechanism he termed "initial floristics" in which old-field
plant community development after abandonment unfolds from an
initial flora already residing within the soil, without
additional increments by further invasion. As each successive
d
species or group subside, another that has been present from
the beginning, assumes dominance. In a forest succession
sequence, eventually only the trees are left. Egler noted
that the actual development of vegetation in an old-field is
a function of both autogenic processes but that in secondary
succession, initial floristics determined the composition of
the resulting community and relay floristics played a
relatively minor role. He also noted that allogenic factors
were important determinants of community composition.
The Clementsian and Gleasonian views of succession define
opposite poles within the field of ecology. In the modern
analogs, the arguments have been refined but many of the key
issues and differences have remained intact. The Clementsian
tradition has a modern synthesis in systems ecology, while the
modern proponents of the Gleasonian view are typically aligned

6
with the discipline of population ecology. Dichotomies still
center on questions of holism versus reductionism, the
evolutionary unity of communities, and whether ecosystems
possess emergent properties.
E.P. Odum (1969) provided a modern ecosystem
reformulation of Clementsian succession. Odum noted the
similarity of succession to the development of individual
organisms and converged with Clements' description of
succession as an orderly process that is reasonably
directional and therefore predictable, resulting from
modification of the physical environment by the community
(autogenic) and culminating in a stabilized (climax, mature)
ecosystem with homeostatic properties.
Confusion developed when some ecologists described the
ecosystem as having an evolutionary unity. Patten (1975)
called the ecosystem a "coevolutionary unit." Webster et al.
(1974) stated that a basic assumption of ecosystem analysis
is that ecosystems are units of selection and evolve from
systems of lower selective value to ones of higher selective
value that optimize utilization of essential resources. Other
ecologists did not view communities or ecosystems as
evolutionary units because inheritance of genes is passed
separately by the many species.
H.T. Odum (1983) describes succession as a self
organizing process by which ecosystems develop structure and
processes from the available choices supplied by seeding. The

7
organization develops new programs for succession with which
species prevail that are reinforced by controls and material
cycles of the next larger system. This view has maximum
power as a self-design principle, in that there is survival
of those combinations of components that contribute most to
the collective power of the system. Species combinations are
reinforced that divide up and optimize the use of resources
to collectively maximize productivity, and species
substitutions occur through time as new choices are offered
and selected. Some Darwinian selfish selection is involved
but is regarded as secondary. Emphasis is on selection of
relationships that make the system perform, with evolution
ultimately occurring but on a longer time interval.
Modern proponents of the Gleasonian individualistic view
(McCormick, 1968; Drury and Nisbet, 1971, 1973; Horn 1971,
1974, 1975; Pickett, 1976; Connell and Slatyer, 1977) find the
classical Clementsian paradigm and its modern incarnation, the
holistic-ecosystem representation, unpalatable. McIntosh
(1982) points out that the studies by these researchers share
at least three characteristics:
1. They are commonly cited in recent discussion of
succession as providing "new" insights for successional
theory.
2. They are explicitly critical of Clements' holistic,
organism theory of succession and of what they interpret
as the successional theory of the organismic, holistic,
ecosystem ecology expressed by ecosystem ecologists.
3. The alternative models of succession proposed advocate
an individualistic, population-based approach emphasizing
life history attributes of organisms and the consequence

8
of natural selection as the essential basis of a modern
theory of succession.
Connell and Slatyer (1977) described three models by
which species may replace each other in a successional
sequence. They assumed no further changes in the abiotic
environment and that certain species usually appear first
because they have the ability to produce large numbers of
easily dispersed seeds, which are not adapted to germinating
and growing on occupied sites.
Model 1 assumes only certain early successional species
are able to colonize a site immediately after disturbance, as
in the "relay floristics" model of Egler and the classical
Clementsian view.
Models 2 and 3 assume that any arriving species may be
able to colonize, even those that typically appear late in
the sequence. These are alternative forms of Egler's "initial
floristics" model. In model 2, early colonists neither
increase nor reduce the rates of recruitment and growth of
later successional species. Species that "appear" later in
the successional sequence are those that arrived either
initially or later but grew very slowly. In Connell and
Slatyer's model of initial floristics, the sequence of species
is determined solely by life history characteristics. In
contrast, model 3 (termed inhibition) holds that once early
colonists secure the available space and resources, they
inhibit invasion by subsequent species and suppress the growth

9
of those already present. Invasion is only possible when the
dominating species are damaged or killed, thus releasing
resources. In model 3, the tolerance of late successional
species is important, as it allows them to survive long
periods of suppression.
Wetland Succession
Much of the debate on succession focuses on the factors
controlling the course of community development. Controlling
factors are typically grouped as autogenic, those generated
by the biological community itself, or allogenic, coming from
outside the biological community.
In some views of succession (Clements, 1916, 1920)
wetlands were considered a transient stage between aquatic
communities and a terrestrial forest climax. In this concept,
aquatic areas may gradually fill from sediment deposition and
organic peat formation. Emergent macrophytes, shrubs, and
trees gradually appear, and the community continues to
transform the wetland site into a terrestrial one. Where
sediment accumulation raises the ground elevation above water
levels, a change to drier vegetation is observed.
In wetlands where inorganic sediments are not being added
and land is not being elevated, peat formation may not proceed
beyond water levels (Odum, 1984). In warm climates, organic
matter oxidizes or burns in dry weather, arresting succession.
Many wetland ecosystems in this sense are a form of climax.

10
A major influence of Clements' ideas on wetland ecology
was the tendency to interpret zonation patterns in wetlands
as indicators of future successional trends. Succession in
wetlands was viewed as a directional, autogenically-driven
process leading inevitably to some terrestrial climax.
Evidence leads to the conclusion that both allogenic and
autogenic processes act to change wetland vegetation and that
the Clementsian idea of a regional terrestrial climax for
wetlands is often inappropriate.
Van der Valk (1981) claims that Pearsall (1920) was one
of the first to apply Clements' concept of succession to
wetlands. The concept of the monoclimax was eventually
replaced by Whittaker's concept of pattern climax (Whittaker,
1953), which was based on gradient analysis studies that
documented the independent distribution of species along
environmental gradients. The effect was to de-emphasize the
successional interpretation of seres, or vegetative zones in
the case of wetlands, and to focus on the correlation of plant
species with specific types of environmental conditions.
Van der Valk (1981) proposed a "new" definition of
wetland succession, based on the ideas of H.A. Gleason (1917,
1926, 1939) that did not presuppose the existence of a climax
vegetation. Van der Valk defined succession as a change in
the floristic composition of the vegetation of an area from
one year to another which, is narrower than Gleason's
definition of it as any change, quantitative or qualitative,

11
in the vegetative cover of an area. In the van der Valk
model, succession occurs whenever a new species becomes
established or an existing one is extirpated.
The model is based on the life history characteristics
of the wetland species and the interaction of the species with
the prevailing environmental conditions (see Figure 1). Van
der Valk classified wetland plant species into 12 life history
strategies based on potential life span, propagule longevity,
and propagule establishment requirements. Under this scheme,
each life history type has its own unique set of
characteristics and associated responses to prevailing
environmental conditions, which act as a "sieve" in
determining the species composition of the wetland. As
environmental conditions change, so does the action of the
sieve and, therefore, the species present.
The van der Valk model focuses on the wetland seed bank
as the key biological component. The functional significance
of seed banks lies in providing the plant community with an
in situ means of regenerating from naturally occurring
disturbances (Grime, 1978). Van der Valk (1981) and van der
Valk and Davis (1976, 1978) have aptly documented and
demonstrated the role seed banks play in the vegetation
dynamics of prairie glacial marshes that undergo cyclic
patterns of flooding-drawdown-drought. In prairie glacial
marshes and other marsh systems (Keddy and Reznicek, 1982;

Figure 1. General model of Gleasonian wetland succession
proposed by Van der Valk (Source: after Van der Valk 1981)

Environmental Sieve (State: Drawdown)
WETLAND
VEGETATION
fit
" AD-II
A S II
-PD-II
- PS-II
t
Potentially
Extirpated
Species
AS- AS- PS- PS- VS- VS-
I II II II It
HEJY
A-Annual
P-Perennial with Limited Life Span
V-Vegetatively Progated Perennial
D-Dispersal Dependent Species Short-Lived Seeds
S-Seed Bank Species Long-Lived Seeds
I -Species Established Only in Absence
ol Standing Water
11-Species That Can Be Established In Standing
Water

14
Leek and Graveline, 1979), seeds remain dormant, yet viable,
in the seed bank during periods in which environmental
conditions are unfavorable for germination, growth, and
development of the population. In wetland and upland
communities, seed banks provide a mechanism for rapid recovery
from catastrophic mortality resulting from fire (Johnson,
1975), clear-cutting (Marks, 1974), and drought (Myers, 1983).
Marks (1974) has shown that the rapid response of pin cherry
to clear-cutting in the Hubbard Brook ecosystem helped
minimize the effect of canopy removal on nutrient losses from
the ecosystem. Egler's initial floristic hypothesis portrays
old-field succession as a seed bank response.
The van der Valk wetland model can be reformulated using
energy circuit language (Figure 2). Van der Valk's 12 life
history categories are simplified to mudflat annuals, emergent
macrophytes, and aquatic macrophytes. The actual composition
of the wetland is determined by the interaction between the
existing plant community, the propagules present, and
environmental conditions. Logic switches are used to indicate
the actions of the "environmental sieve."
Role of Consumers
Various roles are attributed to consumers in ecosystems
beyond simple trophic relationships of herbivory and
predation. These non-trophic interactions typically involve

Environmental
i Conditions J
Figure 2. An energy circuit diagram of a Gleasonian model of wetland succession
(redrawn from Van der Valk 1981).

16
hypothesized feedback loops between species, termed indirect
effects. Non-trophic interactions are concerned with
ecosystem structure and function, which, according to the
individual selection theories of traditional population
ecology, are not subject to adaptive evolution.
It has been suggested that heterotrophs regulate
autotrophs and thereby control the rate of energy production
( O'Neil et al., 1975; Lee and Inman, 1975). Owen and Weigert
(1976) asked the question, whether consumers maximize plant
fitness, and developed a hypothesis that consumers, like
pollinators, have a mutualistic relationship with plants. They
suggested that plants may exploit consumers to increase
fitness. If, through the action of consumers, a nutrient that
is in short supply is made more available to the plant, the
relatively small amount of photosynthate lost may be more than
compensated.
Mutualistic interactions may involve a direct trophic
link, such as those just described, but other non-trophic
interactions between species very much affect fitness but do
not involve competition or predation. For example, intensive
fiddler crab (Uca pugnax) activity in the tail-form of
saltmarsh cordgrass (Spartina alterniflora) stands improves
soil drainage, oxygenates marsh sediments, and increases
belowground decomposition of plant-generated debris (Bertness,
1985) all of which can affect the growth rate of the
cordgrass.

17
Population ecologists view non-trophic interactions as
byproducts of the evolutionary process. Wilson (1980)
described the problem as one in which traditional
investigators within the discipline of population ecology
assumed that the community structure was already in place.
They then focused on relatively superficial forms of
competition and predation, while ignoring the structure that
actually determined the parameter values of the models.
Productivity in ecosystems depends on recycling and
conservation of nutrient resources. The actions of consumers
may cause a nutrient in short supply to become relatively more
available. When primary production is nutrient-limited,
heterotrophic activity, which accelerates mineralization, may
help increase
it. The
importance
of
heterotrophs
as
regulators
of
ecosystem
processes
far
outweighs their
importance
as
measured by
calories or
grams of matter,
but
rather lies in how their characteristics affect or regulate
ecosystem processes (Chew, 1974; Odum, 1982).
Numerous examples can be found of the regulatory role
played by consumers. Vertebrate herbivores have been shown
to increase productivity of grasslands (McNaughton, 1975).
Platt (1975) showed the influence that badger mounds have on
soil properties and the pattern and distribution of some plant
species. Burrowing rodents can act as nutrient pumps,
bringing materials to the surface from below (Abaturov, 1972) .
In forest soils, litter accumulated and decomposition slowed

18
when earthworms were removed (Witkamp, 1971). Earthworms
stimulated the growth of potted barley seedlings, possibly by
increases in vitamin B12 (Atlavinyte and Dacinlyte, 1969).
Dung beetle activity was found to be almost as effective as
mechanical mixing in enabling plants to benefit from the
nutrient storages in dung (Bornemissza and Williams, 1970).
Leaf cutter ants (genus Atta) reduced primary productivity by
reducing leaf area, but more than made up for that loss by
returning materials to the soil (Lugo et al., 1973).
Mound-building ants can produce localized concentrations
of organic matter and nutrients, resulting in changes in
densities of bacteria, fungi, and plants (Czerwinski et al.,
1971). They can affect the physical and chemical aspects of
soil as well as the distribution of plants, bacteria, and
fungi, and are important in making channels and burrows. Hopp
and Slater (1948) felt ants could be as effective as
earthworms in creating conditions for improved plant growth,
while Thorpe (1949) indicated that ants may produce greater
effects than earthworms. Shrikhande and Pathak (1948)
reported that ants increased the organic matter content of
soils second only to earthworms.
Numerous studies have shown chemical differences between
mound and nearby non-mound soils, with evidence of higher
levels of exchangeable cations, micronutrients, nitrogen,
phosphorus, and organic matter, as well as differences in pH
and conductivity (Czerwinski et al., 1969, 1971; Gentry and

19
Stiritz, 1972; Rogers and Lavigne, 1974; Wali and Kannowski,
1975; King, 1977; Petal, 1978; Levan and Stone, 1983; Culver
and Beattie, 1983). Enhanced nutrient levels in mound soils
are attributed to microbially-mediated mineralization of
organic waste products in the mound (Petal, 1978) This is
supported by the work of Czerwinski et al. (1971), who showed
the abundance of bacteria and fungi in ant mounds is higher
than in the surrounding soil.
Mound-building ants profoundly alter the soil profile
characteristics at their nest sites ( Baxter and Hole, 1967;
Salem and Hole, 1968; Wiken et al., 1976; Wali and Kannowski,
1975; Alvarado et al., 1981; Levan and Stone, 1983). Mound
soil has been shown to differ from nearby soil in bulk
density, porosity, and infiltration capacity (Rogers and
Lavigne, 1974; Rogers, 1972; Wali and Kannowski, 1975).
Through their influence on soils, ants can affect
microtopographic heterogeneity, which can influence species
composition, standing crop, and successional status of the
local vegetation (Petal, 1978; Rogers, 1974; Gentry and
Stiritz, 1974; King, 1977; Culver and Beattie, 1983). Herbs
flourish on abandoned nest sites of harvester ants (Gentry and
Stiritz, 1972) and are known to affect seed distribution.
Ants are known to alter seed shadows in deserts (Bullock,
1974; O'Dowd and Hay, 1980), mesic environments (Beattie and
Lyons, 1975; Handel, 1987; Beattie and Culver, 1981), and
tropical forests (Roberts and Heithaus, 1986). Some plant

20
species known as myrmeccochores have a food body on their seed
that is eaten by ants, which then disperse the seeds while
returning food materials to the mound.
Competing Paradigms of Succession
The preceding discussions have revealed five competing
paradigms of succession: two individualistic, life history-
based models (initial floristics and inhibition) and three
holistic ecosystem models (relay floristics, coevolution, and
self-organization). An energy circuit language diagram of
succession is shown in Figure 3a that includes early and late
stage plants, seeding, and nutrient recycle. Additional
controls and pathways are added to represent various paradigms
for the interactions between early and late successional
species (Figures 3b-3f). The concept of each paradigm is
briefly summarized below.
Initial floristics. Early and late successional species
coexist with the same resources (Figure 3b) The early
species modify the site so that it is not suitable for their
continued reproduction, but have no effect on the recruitment
of late species.
Inhibition. Early and late successional species compete
for available space and resources, such as light, nutrients,
and moisture (Figure 3c). Rapidly dispersing, fast growing
early species colonize available open space and capture
available resources, inhibiting the establishment of later

Figure 3. Energy systems diagram of succession: (a) with some of the main pathways of
organization, seeding, and nutrient cycle; (b) control in "initial floristics"; (c)
control with inhibition; (d) control with "relay floristics"; (e) control with
coevolution, pathways permanent; and (f) controls from self-organization and
reinforcement from animals and larger surrounding system.

(a)


24
species. Slower growing late successional species can only
become established when the early colonizers have been killed
or disturbed.
Relay floristics. Late successional species are unable
to become established on bare ground; they arrive and become
established only after some critical level of development has
been reached (Figure 3d) Late successional species gradually
displace the early colonizing species. Competition for light
results in poor growth and reproduction by early colonizing
species, when later successional species are established.
Coevolution. An expanded version of the relay floristics
model that also recognizes a long-term relationship between
species (e.g., feedback relationships between and among
trophic levels) (Figure 3e).
Self-organization. Producers, consumers, and decomposers
are linked in a dynamic feedback network in which each trophic
level is composed potentially of many species. Actual species
composition of the community is a function of the system's
self-organizing choices, which reinforce those combinations
that optimize the use of resources and maximize productivity
(Figure 3f) Controls and reinforcement are shown from
animals and larger scale phenomena of the surrounding system.
Changes in Paradigms
The continuing contradictions about succession after many
decades of study suggest that more may be involved than a

25
straightforward, objective, scientific consideration. Ecology
and the succession concept may be in the midst of a revolution
(McIntosh, 1983) and specifically a change in paradigms, which
Kuhn (1970) has described as the way a scientific discipline
progresses.
A common and idealized image of a scientific discipline
is that it is universal, objective, and unbiased, with free
communication and mutual comprehension among its members.
Historians of science show this to be a simplistic and
inaccurate view, and discuss the hypothesis of the "invisible
college" as the basis of the organizational patterns
associated with major advances and changes in paradigms within
a scientific discipline (Crane, 1972; Griffin and Mullins,
1972). The invisible college hypothesis argues that any
discipline, especially one in a state of change, is subdivided
into loose networks of scientists with varying degrees of
cohesiveness and continuity. According to Griffin and Mullins
(1972) such networks conform to the following criteria:
1. Their members believe they are making major changes in
concept or methodology and the word revolution is much
in evidence.
2. Members do not consistently observe the attitude of
disinterested objectivity typically associated with
scientists and may be passionate and one-sided advocates
of a "ruling theory."
3. There is commonly a close, even somewhat closed, informal
communication network within the network.
One or more outgroups are typically recognized and
increasingly opposed as the network becomes more tightly
organized.
4.

26
5. A network is commonly identified with a leader who may
provide intellectual and/or organizational coherence.
The work that the network associates itself with
generally has originated, or is centered on a particular
place with a more or less well defined origin and time
span.
Some of the confusion and contradictions concerning
succession may be attributed to a lack of understanding of the
history and sociology of the succession concept and the
origins and evolution of the competing paradigms, or
conceptual models. Confusion often arises from ignorance,
as proponents of a "new" view may be unfamiliar with early
work in the field, current thinking within other groups in the
field, or their nomenclature and terminology. The invisible
college hypothesis may help explain the divergent positions
in ecology specifically concerned with succession.
A scientific community upholds an old paradigm in spite
of its inadeguacies and contradictions until a new and better
one emerges and is accepted. The paradigms of succession
appear to be flawed and a new paradigm will likely emerge from
a more eclectic synthesis. It is clear that an explanation
of the cause and mechanism of succession, and development of
a reasonable consensus on a paradigm of succession, will
require a careful analysis of the historical background,
biases and premises, and philosophy of the idea and its
practitioners, critics, and proponents.
As a framework for formulating this bridging paradigm,
McIntosh (1981) provided a number of questions to be answered:

27
1. Do the extended observations of succession support a
general theory of the successional process that is (a)
orderly, directional and predictable; (b) controlled by
biotic factors, (ie., autogenic); and (c) leads toward
an equilibrium state in either or both its biotic or
abiotic attributes?
2. Is the claim of some ecologists that successional
phenomena are reducible to theories of natural selection
justified? How do population theory and life history
strategies explain and predict ecosystem attributes?
3. What are the emergent properties claimed to justify
ecosystems theory? If population phenomena are not
additive, what is the measure of integration?
4. Does the evolution of ecosystems have any reasonable
explanation in evolutionary theory?
5. Is the reduction of ecosystem to trophic numbers, seen
by Hutchinson (1942) and Ulanowicz and Kemp (1979) as the
essence of the genius of Lindeman, holistic or simply a
collective property as stated by Salt (1979)? In what
sense is the ecosystem approach to succession holistic?
6. Can reasonably explicit distinctions be made between a
small-scale disturbance initiating the traditional serule
within the community and a large scale disturbance
initiating an earlier stage of a sere? Can autogenic and
allogenic disturbances be clearly distinguished or are
they interdependent, as suggested by White (1979)?
7. Can a theory of succession be developed to incorporate
a sere regularly reaching an equilibrium over an extended
area, as argued by Bormann and Likens (1979) and Franklin
and Henstrom (1981), and a sere that is largely
interrupted by disturbance as described by Raup (1957)
and by Heinselman (1981)? Can the achievement of
equilibrium be related to a trajectory toward
equilibrium?
Hypotheses and Objectives
Research for this dissertation involved nearly 4 years
of field work on mined lands in Polk County, Florida. The
main objectives were (1) to evaluate the process of initial

28
plant community establishment in wetland and terrestrial
communities and interpret the results and observations through
competing paradigms of succession (initial floristics,
inhibition, relay floristics, coevolution, and self
organization) (2) to determine the role played by mound
building ants in the developing community and assess this role
with the prevailing paradigms, and (3) identify possible
technigues for enhancing succession on strip-mined land.
These overall research objectives were addressed in three
separate but related field studies.
Marsh Development
Seed bank survey. As an initial step in understanding
and enhancing the design of self-maintaining ecosystems, seed
bank dynamics were examined. A survey was made (1) to assess
the size and species composition of seed banks in selected
marsh ecosystems from natural and post-mining landscapes, (2)
to identify the ecological role and significance of seed banks
in marsh community dynamics, and (3) to evaluate the
feasibility of establishing marsh ecosystems by helping form
seed banks.
Marsh transect study. Transects were used to compare the
herbaceous component of the wetland that developed from
natural processes to that created by spreading muck from an
onsite donor marsh. Stages of vegetation establishment were

29
examined to test the hypotheses that (1) differences in the
initial floristics in the two treatment areas (mucked versus
unmucked) result in communities of very different species
composition and (2) differences in the perennial macrophytes
of the two different treatment areas would be maintained
through time.
Both seedbank and transect studies were used to evaluate
the Gleasonian model of wetland succession proposed by van der
Valk (1981).
Upland Forest Development
Upland forest studies examined the relationships between
early colonizing plants and late successional trees on an
unvegetated upland site. The colonizing annuals, biennials,
perennials, and low shrubs found on old fields were designated
early successional species. The interactions between early
and late species were examined to determine which paradigms
explained ecosystem development (inhibition, initial
floristics, or relay floristics). Field plot experiments
using species removal and addition were designed to determine
the effect, if any, of colonizing vegetation on establishment,
growth, and survival of tree species.
Four treatments were used: (1) natural colonization, (2)
enhanced colonization with seeds of several common old-field
weeds, (3) addition of legume species, and (4) periodic
weeding to keep the plots generally free of any colonizing

30
vegetation. In both the enhanced colonization and enhanced
legume treatments, the natural colonization process was also
allowed to occur. Criteria for accepting or rejecting the
competing paradigms are given below.
1. If seedlings grew better with either the enhanced
colonization, natural colonization or legume treatments,
then the initial floristics and inhibition paradigms were
rejected in favor of the relay floristics paradigms.
2. If seedlings grew better in weeded plots, then the
initial floristics and relay floristics paradigm were
rejected in favor of the inhibition model.
3. If seedlings grew about the same in the weeded plot as
in other treatment plots, then the relay floristics and
inhibition paradigms were rejected in favor of the
initial floristics.
Mound-Building Ants and Ecosystem Development
Early successional mined lands provide an opportunity to
investigate interactions between species as the community is
developing in a simple system with a few producers and a few
consumers. Three field observations aroused interest in the
role and effects of mound-building ants in such a system.
First, fire ants (Solenoosis invicta) are one of the
earliest arriving invertebrate consumers on young strip-mined
lands. In central Florida, fire ant populations were usually
well established in the first year after mining ceased.
Second, herbaceous plants, especially grasses, growing
on ant mounds were typically more robust, with a richer green
color than plants found on adjacent non-mound soil. This

31
observation led to the hypothesis that mound soils were more
fertile because of the ants.
Third, it was noted that overburden soils high in clay
formed surface crusts that inhibited water infiltration, but
mound building and tunneling by ants broke the surface crust
and maintained the soil in a more friable condition.
Fire ants are omnivorous scavengers who forage the
landscape, gathering food materials and returning with them
to the mound. This activity concentrates otherwise dilute
nutrient materials, which may be one of the primary functions
of ants in the ecosystem. If ant mounds represent a localized
concentration of nutrients in the form of insect parts, plant
parts, feces, and waste products, then they are also likely
to be foci of microbial activity mineralizing organically
bound nutrients. The ant colony and mound system may recycle
materials that are scarce in the developing ecosystem.
Mound-building ants may alter the soil profile and
influence particle size distribution, bulk density, porosity,
and infiltration capacity. These soil alterations may affect
primary production.
Relationships are shown in diagrammatic form. Arrows on
a causal loop diagram of the ant model indicate pathways of
influence (Figure 4) A "+" used at an arrowhead indicates
an increase in the adjacent item. For example, a larger
concentration of food materials in the mound leads to a
higher level of microbial decomposers. A indicates a

Figure 4. Causal loop diagram showing feedback relationships between mound-building
ants, plants, other consumers, water infiltration, soil development and nutrient cycle.
u>
to

33
decrease in the item at the arrowhead. The ant model depicts
two positive feedback loops, one linking plants-ants-microbes
and one linking mounds-soil-water infiltration. The arrows
represent causal relationships that can be experimentally
evaluated.
An energy circuit language formulation of the ant model
(Figure 5) also provided a summary of ecosystem components and
energy/material pathways for directing research efforts.
Research guestions were:
1. Do mound-building ants concentrate nutrients in the
landscape?
2. If they do concentrate nutrients, does this provide a
feedback to the primary producers (plants), establishing
a non-trophic interaction or indirect effect and
eventually a feedback to themselves?
3. What function does mound-building work serve for the
developing ecosystem?
4. If ants are found to provide positive feedback to the
developing ecosystem, are there ways to further stimulate
feedbacks and enhance succession?
Description of Study Sites
Eight study sites in central Florida were used in the
three phases of the research (see Table 1 and Figure 6) .
Seven of the sites were within Polk County and one in the
northeast Manatee County in the Four Corners area. A brief
description of each site is provided below.
Pasture Marsh. This marsh was approximately 1.0
hectare in size and located on the Mobil Chemical Company's

Figure 5. Energy circuit language diagram of ant model.


36
Table 1. Sites used in marsh
ant study.
study, upland forest
study, and
Sites
Upland
Marsh Forest
Study Study
Ant
Study
Sanlan Marsh
X
Tiger Creek
Reclamation Area
X
Clearsprings Wetland
Demonstration Project
X
X
Whidden Creek
Reclamation Area
X
Four Corners Wetland
Demonstration Project
X
Fort Green Wetland
Demonstration Project
X
X
Natural Marsh
X
Peace River Bay Swamp
X

37
Figure 6. Location of study sites in Polk and Manatee
Counties.

38
South Fort Meade Mine tract. The vegetation within the marsh
was dominated by softrush (Juncus effusus), pickerelweed
(Pontederia cordata), Sagittaria lancifolia. and smartweed
(Polygonum punctatum). The marsh was selected as typical of
the freshwater marshes within the study area, most of which
are subject to grazing.
Peace River Bavhead. This bay swamp is located on a
seepage slope draining to the Peace River on Mobil's South
Fort Meade Mine tract. The swamp had an overstory of sweetbay
magnolia (Magnolia virginiana), red bay (Persea palustris),
and dahoon holly (Ilex cassine). The groundcover consisted
primarily of lizard's-tail (Saururus cernuus) The substrate
consisted of a layer of finely decomposed muck overlying
fibrous peat. The depth of the organic soil averaged
approximately 1 m.
Sanlan Marsh. This marsh developed on an unreclaimed
clay settling area that was mined in the early 1950's. The
site was selected because it was one of the few old,
unreclaimed clay settling ponds that was not dominated by
cattail, primrose-willow, or willow.
Four Corners Demonstration Project. W.R. Grace Company
initiated a wetland reclamation demonstration project at its
Four Corners Mine site in 1979. Four 0.16-ha depressions were
excavated to a maximum depth of 1.2 m in a pine-palmetto
flatwoods adjacent to Alderman Creek in 1978. The area was
not mined, but overburden was removed to a depth below the

39
minimum design grade and then backfilled, simulating
reclamation. Four test plots were established as follows:
1. Plot 1. Control plot, graded and left for natural
revegetation.
2. Plot 2. Hand-planted with plant material taken from
nearby natural marsh, including maidencane (Panicum
hemitomon) pickerelweed (Pontederia cordata) and Juncus
effusus.
3. Plot 3. Mulched 30 cm deep with donor muck from a nearby
marsh.
4. Plot 4. Tree plot where 95 trees comprising 16 different
species were transplanted from a donor site on Alderman
Creek.
Whidden Creek Reclamation Area. The Whidden Creek area
was mined by Gardinier Phosphate in 1982 and 1983. The area
was reclaimed in 1983 using an integrated landscape approach,
that sought to create a small drainage basin discharging to
Whidden Creek.
Tiger Bay Reclamation Area. The Tiger Bay area was mined
by International Chemicals and Minerals, Inc. (IMC) in 1982
and 1983. The area was reclaimed in 1983 as a land-and-lakes
area typical of the industry's reclamation practice.
Clearsprinas Wetland Demonstration Project. Work on this
18-ha wetland demonstration project began in 1978. The
project was a joint effort of IMC, the Florida Game and
Freshwater Fish Commission, and the U.S. Fish and Wildlife
Service. The site adjoins the Peace River and was designed
to establish physical site characteristics similar to those
that produce and maintain floodplain wetlands. Basins were

40
created to encourage emergent plants, store water onsite, and
create fish and wildlife habitat. Test plantings of 15
different tree species, planted as bare root seedlings were
done in 2 6 plots with 400 trees per plot. Freshwater
macrophytes were also planted in the basins.
Fort Green Wetland Demonstration Project. This wetland
project is part of a 148-hectare reclamation project carried
out by Agrico Mining Company at its Fort Green Mine in
southwestern Polk County (Figure 6) The site, which was
mined in 1978 and 1979, was recontoured to create 61 ha of
wetlands and 87 ha of uplands (Figure 7) The reclamation
began in 1981 and was completed by May 1982. The project
sought to create open water, freshwater marsh, freshwater
swamp, and upland habitat.
The site is gently sloping with a range of 40.23 m down
to 35.40 m mean sea level (msl) in the wetland basin. The
wetland basin receives runoff and baseflow from the
surrounding uplands. The basin has a highwater discharge to
the adjacent floodplain of Payne Creek when the surface water
elevation reaches approximately 36.58 m msl. Within the
wetland basin are several deep holes that serve as deep water
habitat and aquatic refuge during times of drought. These
deep pools have spot elevations ranging from 31.85 to 35.36
m msl.
The donor muck was transported from a nearby donor marsh
and spread in the littoral zone with depth varying from 2.5

41
to 30 cm. Approximately 15 percent of the littoral zone
received the muck treatment.

Pood
Upland
Figure 7. Fort Green wetland reclamation area showing marsh transect locations
approximate vegetation zones, and muck treatment zones.

METHODS
Marsh Development
Seed Bank Survey
The seven wetland sites sampled in the seed bank survey
include natural wetlands, and unreclaimed and reclaimed
wetlands on mined lands (Table 2 and Figure 6). At each site,
one to several major vegetation zones were sampled with a 5-cm
diameter, hand core sampler that was pushed into the substrate
to the mineral soil layer. The depth of any overlying organic
layer was noted, and only the upper 10 cm of the core was
retained. Four individual cores were combined to yield a
composite sample, with three composite samples taken in each
vegetation zone selected. Samples were stored in sealed
plastic bags at 4C until they were processed.
All live plant material was removed from the samples to
prevent confusing in seed germination results with any vegeta
tive regeneration. Once the plant material was removed, the
samples were placed in wooden flats (25 cm x 25 cm) containing
approximately 4 cm of sterilized gravel mixed with tailings
sand; the samples were approximately 2 cm deep when spread out
evenly in the flats. The flats were then placed
43

Table 2. Sample locations and site characteristics.
Site
County
Vegetation Zone
Substrate
Unreclaimed Mine Site
Sanlan marsh (30 yr old)
Polk
Juncus-Polvaonum
Eichhornia
Clay
Clay
Reclaimed Mine Sites
Clearsprings (4 yr old)
Polk
Polvaonum-Ludwiaia
Clay-overburden
Fort Green (2 yr old)
Polk
Pontederia (Muck zone)
Open water (Muck zone)
Open water
Muck-overburden
Muck-overburden
Overburden
Four Corners Marsh
(5 yr old)
Manatee
Pontederia (Muck zone)
Pontederia (Planted)
Eleocharis (Control)
Polvaonum-Ludwiaia
Muck-sand
Sand
Sand
Sand
Natural Wetlands
Pasture marsh
Polk
Pontederia-Juncus
Muck-sand
Peace River bayhead
Polk
Saururus
Peat
Lake Kanapaha *
Alachua
Amaranthus
Echinochloa
Open water
Muck-sand
Muck-sand
Muck-sand
Four Corners marsh
Manatee
Pontederia-Juncus
Muck-sand
* Lake Kanapaha not sampled in this study, results from previous study provided
by Dr. Ronald Myers

45
outdoors in large plastic tubs containing sufficient water to
maintain a saturated soil condition.
Seedling emergence by species was monitored through time.
Unidentified seedlings were counted, transplanted to flower
pots, and allowed to mature until they could be identified.
Marsh Transect Study
Six permanently marked transects were established in
October 1982: three each randomly located within the muck
treatment areas and the unmucked, overburden areas (see Figure
7) All transects began in the shallow littoral zone and
extended upslope through the transition zone to the upland
edge. The three muck treatment transects totaled 309 m and
the three overburden transects totaled 275 m. The difference
in total length of the two treatment groups was a result of
the slope differences at the random locations.
The plant communities along the transects were monitored
using a modification of the standard line-intercept method
(Phillips, 1959; Smith, 1980; Canfield, 1941) to record the
percent cover by species along each transect. The standard
method consists of taking observations along a transect line
and noting the identity of any plant touched by an imaginary
plane extending vertically above and below the transect line.
The distance, or interval, of the planar intercept is also
recorded. The individual intervals are totaled for each

46
species to yield total cover, which can be standardized to
percent cover.
The modification of the standard method used in this
study consisted of identifying patches or intervals of species
occurrence even when the cover by the particular taxa within
the patch was less than 100 percent. With this modified line-
intercept technique, the interval distance as well as the
percent cover by the taxa within the interval was recorded.
The modification provided a more rapid method of measurement
that was also relatively accurate and well adapted to
measuring changes in vegetation across zones and following
changes through time.
The transects were sampled over four growing seasons:
November 1982; May, July, and November 1983; March, July, and
November 1984; and June 1985.
Elevations along each transect were measured on 1.5 m
intervals. These elevations were converted to mean sea level
(msl) based on a reference to the measured surface water level
in the wetland basin that day. A continuous water level
record was provided by a surveyed, permanently mounted water
level recorder. The daily summary values for the period of
study were supplied by Agrico Mining Company.

47
Upland Forest Studies
An upland area on the west side of Parcel 6 at
Gardinier Phosphate Company's Whidden Creek Mine (Figure 6)
was cleared in late October 1983. The cleared area was 63 m
by 63 m with a gentle slope from the south to the north.
Seedling and direct-seeded plots were located in early
December 1983 and two experiments were set up adjacent to
each other (Figure 8). The experimental design was a nested
analysis of variance with four experimental treatments:
colonizing species allowed, colonizers weeded out, colonizers
added, and legumes added. Within each of the two experiments
were four replicates for each treatment, for a total of 32
plots. All treatments were randomly assigned to plots.
The experimental treatments used in both the
seedling and direct-seeded plots were the addition of seed of
four colonizing species, the addition of seed of four legume
species, the removal of all colonizing species through
weeding, and a natural invasion of colonizing species. The
first two treatments involved the application of seed, which
was completed just prior to planting the tree seeds or
seedlings. The initial site clearing in October left all
plots free of vegetation at planting time.
The enhanced colonizer treatment included four of
the most common species found on old fields and abandoned mine
lands in central Florida: natal grass (Rhvnchelvtrum repens),

48
Seedling plots
Seed plots
ptot with buffer
Figure 8. Schematic layout of seed and seedling transplant
plots on upland study site at Gardinier's Whidden Creek Mine
area.

49
groundsel (Baccharis halimifolia), dogfennel (Eupatorium
capillifolium), and broomsedge (Andropogon virginicus).
Four species were added in the enhanced legume treatment:
Cassia obtusifolia Sesbania macrocarpa. Sesbania punicea,
and Sesbania vesicaria. In the direct-seeded plots, 50 seeds
of each legume were added for a total of 200 seeds per plot;
110 seeds per legume, totaling 440 seeds per plot, were added
to seedling plots receiving this treatment. In both cases,
the seeding rate gave a density of 22 legume seeds/m2.
Seeds for the enhanced colonizer and enhanced legume
treatments were applied by mixing the seeds with some over
burden soil from the plot and hand broadcasting the mixture
onto the plots. The soil was disturbed by hand with rakes and
cultivators, to mitigate the effects wind would have on
surface spread seeds of these wind-dispersed species. All
plots were subsequently disturbed as part of a preplanting
treatment. Planting and preplanting treatments were carried
out in December 1983.
The weeding treatment was administered quarterly in
March, May, June, and September for both the transplanted and
direct-seeded plots. All colonizing plants were hand-weeded
and removed from the plots.
Heavy rains in the first month after planting created
several erosion rills running through the plots. To prevent
cross contamination by seeds washing out of one plot and into
another, hay was spread on the magins of all plots that had

50
downslope neighbors. All major erosion rills on the site were
mapped as an aid to interpreting results. In addition,
several rills that had developed through the seed plots were
diverted to interplot areas with a shallow, diversion trench.
Once colonizing vegetation began to appear in early spring of
1984, it afforded a modest degree of soil stabilization and
the severity of the erosion diminished considerably.
Direct-Seeded Plots.
Seeds of seven species were used in the direct-seeded
test plots seeds: sweetgum (Licruidambar stvraciflua) cabbage
palm (Sabal palmetto), live oak (Ouercus virginiana), laurel
oak (Ouercus laurifolia), southern magnolia (Magnolia
grandiflora), sugarberry (Celtis laevigata), and pignut
hickory (Carva glabra). These seven taxa were considered
representative of common mesic hardwood species of central
Florida.
The seeding rate per plot was 50 seeds per species,
yielding 350 seeds per plot. Each plot planting area was 9 m2
(3 m by 3 m), resulting in a density of 39 seeds/m2.
The plots were arranged in a 6 by 3 grid with two of the
plots remaining unused (see Figure 8) Treatments were
assigned randomly to the plot grid. Each total plot was 7 m
by 7 m, which allowed for a 2-m buffer all around the 9m2
planting area. The seed mix was hand broadcast onto the plots
after the soil was disturbed, and the treatment seeds were

51
added if required were. The plots were then raked lightly to
incorporate the seeds into the substrate.
The seed plots were measured in March and October 1984
and the species, height, and growth condition of each seedling
in each plot was recorded. The location of each seedling was
recorded as well so the fate of individuals could be followed.
Seedling Transplant Plots
In the seedling test plots, three mesic hardwood species
were used: sweetgum, live oak, and cabbage palm. The
planting stock for sweetgum and cabbage palm was 8-month-old
containerized seedlings grown in overburden soil. The oak
seedlings were 1-month-old bare root seedlings.
Ten individuals of each species were used in each of the
16 seedling plots, yielding 30 trees per plot and 480
seedlings total. Tree seedlings were planted after the soil
was disturbed and any treatment seeds were added. The 30
trees were randomly assigned to the grid, and the same
planting schematic was used in all the plots (see Figure 9).
The total area of each seedling plot was 8 m by 9 m,
allowing for a 2-m buffer around an actual planted area of 4
m by 5 m. Seedlings were planted on approximately 1-m
centers.
The severe winter freezes of December 1983, and January
February 1984 killed many of the planted seedlings. As the

52
Seedlings planted on 1m centers
C Cabbage Palm
S Sweetgum
L Live Oak
Figure 9. Schematic for planting in Gardinier seedling plots.

53
freezes occurred before any possible treatment effects could
have been exerted, all of the freeze-killed seedlings were
replanted on March 27, 1984, which was then used as the
starting date for growth measurements on the seedling plots.
The plots were measured again in September 1984. At the time
of measurement, the height of each seedling and growth
condition were recorded.
Mound-building Ants and Upland Succession
Survey of Mound Density
Mound densities on the 1-year old IMC Tiger Bay site,
the 2-year old Agrico Fort Green site, and the 5-year old IMC
Clearsprings site were sampled. Replicate 5 m by 5 m plots
were semi-randomly located at each site, and the location,
diameter at base, height, general condition, and level of ant
activity of each mound within each plot were recorded.
Physical Soil Analyses
Bulk density. Bulk density of mound and non-mound soils
at the Fort Green Payne Creek site was sampled with a bulk
density core sampler. Seven mound and seven non-mound samples
were taken. The samples were oven dried at 103 C until a
constant weight was attained, and the density was determined
based on the volume of the sampler and its oven-dried weight.

54
Infiltration tests. Soil water infiltration differences
were measured at the Fort Green site using the paired
infiltrometer technique (Bertrand, 1965). A metal cylinder,
16.5 cm in diameter and filled with water, was used to measure
the rate of water intake of the soil. The metal cylinder was
placed on the ground and driven into the soil with a rubber
mallet to a depth of approximately 5 cm. A circular berm
approximately 10 cm high and 60 cm in diameter was then
created around the metal cylinder. The area enclosed by the
berm served as the outer cylinder. Both cylinders were
maintained at approximately constant head, or depth, by the
addition of water. The amount of water lost through the inner
cylinder over a measured time interval provided an estimate
of the infiltration rate. The inf iltrometer test was not
designed to measure absolute infiltration rates but rather as
a measure of relative infiltration rates in side-by-side
comparisons. Three such comparisons were made. The
first used three infiltrometers, with one placed over an ant
mound, one on an adjacent grassed area typical of the site,
and a third on a bluegreen algae flat. This test was run for
120 minutes. The second test, which lasted 60 minutes,
compared the rates of another ant mound and another "typical"
grassed area. The third test, which lasted 20 minutes, paired
another mound and "typical" grassed area.

55
Chemical Soil Analyses
To test the hypothesis that the activity of the fire ants
changes the chemistry of the mound soil relative to the nearby
soil, paired soil samples were taken at the Tiger Bay, Fort
Green, and Clearsprings reclamation sites. Each reclamation
area consisted of recontoured overburden. Six paired samples
were taken, each pair consisting of a mound sample and non
mound sample from 1 m away, were taken at each site. All
samples were taken with a bucket auger and stored in plastic
bags at 5 C.
Samples were air dried and sifted through a No. 20 mesh
sieve to remove ants from the mound soils. A subsample of
approximately 100 g was taken from the sieved samples to be
used for chemical analysis. The remaining soil was composited
to yield single mound and non-mound sample from each of the
three sites. The composite samples were used for greenhouse
experiments assaying growth differences between the two soils.
Individual soil samples were analyzed for pH, organic
matter content, total kjeldahl nitrogen (TKN), and selected
cations (calcium, magnesium, potassium, sodium, and
manganese).
pH measurements were made with a pH meter with glass
electrode in a 2:1 deionized water to soil dilution, using
10 g of air-dried soil mixed with 20 ml of distilled water.

56
Soil organic matter was determined by the Walkey-Black
wet digestion method (Black, 1965).
Nitrogen was measured as TKN by the semi-micro kjeldahl
procedure, a 1-g sample of air dried soil 7 ml of sulfuric-
salicylic acid was added. After each sample was allowed to
set for 30 minutes, 1 g of sodium thiosulfate was added and
2 g of catalyst were added. The samples were then heated in
a block digester for 5 hours. After digestion, 20 ml of NaOH,
15 ml of boric acid, and 2 drops of indicator were added to
each sample. The samples were then distilled to 60 ml, and
titrated with 0.05 normal sulfuric acid.
A dilute double acid solution (0.025 N H2S04 + 0.050 N
HCl) was used to determine extractable levels of calcium,
magnesium, manganese, potassium, and sodium. Cation levels
in the extracts were measured by atomic absorption-emission
on a Perkin-Elmer model 500 using standard operating
techniques (Perkin Elmer, 1980). One ml of a 10,000 ppm (1%)
lanthanum chloride (LaCls) solution was added to each dilution
series of extract, which resulted in a 1000 ppm solution (.1%)
in each sample. This procedure was necessary to control for
interferences by silicon, aluminum, phosphate, and sulfate,
which depress sensitivity in analyses for these cations.
Equal amounts of lanthanum chloride were also added to
standards and controls before analysis.

57
Plant Growth Study
Several greenhouse experiments were set up to evaluate
a potential growth difference between plants grown on mound
and non-mound soils. The tests used a common early
colonizing grass, vaseygrass (Pasoalum urvillei), and a woody
plant, sweetgum (Liouidambar stvraciflua), as the assay
organisms.
The composite soil samples, as described above, were used
in the growth experiments. Ten plastic seedling tubes were
filled from each of the six composite samples ten plastic.
In each group of ten seedling tubes, five received a seedling
of vasey grass and five received sweetgum. The tubes were
placed in a greenhouse.
At the end of 60 days, the seedlings were harvested and
dried at 103 C to a constant weight. Each vasey grass
seedling was subsequently divided into above- and belowground
portions that were weighed separately. The sweetgum seedlings
were divided into root, stem, and leaf components, each of
which was weighed separately. Leaf area of each sweetgum
seedling was determined by making a xerographic image of the
leaves, cutting out the individual images, and measuring leaf
area with an automatic area meter.

58
Statistical Analyses
All statistical analyses were run with the Statistical
Analysis System (SAS). Data expressed as percent were
transformed by the arcsine function.

RESULTS
Marsh Development
Seed Bank Survey
Results are presented in four general areas: seed bank
density, species importance values, floristic similarity
between samples, and species diversity of samples.
Seed bank densities. The mean number of seeds
germinating in samples from natural, reclaimed, and
unreclaimed marshes in central Florida ranged from 1877 to
72,500/m2 (Table 3). For comparison, seed bank studies of
natural wetlands from Florida, Iowa, New Jersey, and Ontario
have shown a range of density from 6,000 to 156,000 seeds/m2
(Table 4) The overall range of seed bank size (density)
covers three orders of magnitude; the lowest density is
1877/m2 in the sample mucked-unvegetated zone at Fort Green
and the high value is 156,000/m2 from the Sacciolepis striata
zone at Lake Kanapaha, Florida.
The range for natural wetlands samples is 4,000 to
156,000 seeds/m2, with the lowest value from the Peace River
bay swamp (the only forested wetland sample) and the high
value again for the Sacciolepis zone at Lake Kanapaha. A
trend evident in the results from studies at Lake Kanapaha is
59

Table 3. Mean number of germinating seeds per m2* by species for natural wetlands and
reclaimed and unreclaimed marshes in central Florida phosphate district.
four
¡¡Mill
lour Cortera
Clear Sorlaaa
fort Greet
Coraera
Bap
lateral
Paeture
JU£U'
Topad led
Planted
Control
Plaited
South
South
lortb
Topsoiled,
Topaoiled,
Saaap
la rah
larab
Polranaut
iichhoraii
larab
larab
larab
Saaap
Baa la 11 Baala 12
Baila
leietated
Oaieietated
Ooaulched
later aubulata
...
416
500
210
Bacckarli hiiiiiMii
...

...
...
...
...
...
...
...
125
42
292
...
...
...
Carer ap.
...
...
...
125
...
...
...

...
...
...
...
...
Croerua breilfollua
...
...
...
...
<16
...
...
...
...
11
...
...
...
...
...
Croeroa ap.
...
...
...
...
...
...
...
...
...
...
...
...
915
334
960
ClP4I1U rotnndua
ID
...
...
<16
3,750
166
...
...
500
1,666
4,125
1,500
...
...
...
Cmricrn 1
...
...
...
...
...
...
...
...
...
...
...
04
...
...
...
ItilllcHil aalterl
...
...
...
...
...
...
...
...
...
...
...
...
...
...
125
Idiota alba
...

...
125
...
...
...
...
...
250
541
42

...
...
loaatoriai cobpos1t1fo1iua
ID
...
511
...
...
125
16
125
250
375
...
42
14
fimhilini obtaalfollm
...
...
...
...
...
11
...
Graaaea, ookaoaa It
12
:::

12
...
...
...
...
...
125
42
...
...
...
...
...
...
13
ID
D2
...
...

...
...
61
...
...
250
125
...

15
IB
Ifdracntili rerticillata
...
12
11
...
...
...
...
...

1,625

...
...
---
...
D2
...
...
...
...
...
...
...
...
...
...
Iroerlcm autilna
D2
...
...
...
...
...
...
...
...
...
...
166
...
...
...
Jnacna effoana
292
67,211
11,132
51,625
7,625
32,750
31,116
1,500
10,625
1,675
1,916
1,160
209
42
1,210
Jiiacna bofoaloa
125
...
...
12
...
12
...
...
...
...
...
...
...
...
...
Idlilitil rlrrata
292

...
...
...
...
...
...
...
500
416
2,666
1,834
1,375
1,416
LudtitU taloatria
33D
...
...
...
...
...
...
...
...
42
...
...
...
...
...
Ladaliia leotocaroa
...
...
...
...
...
...
...
...
...
14
210
...
...
...
...
Polieoiut ouactatna
...
5,250
292
2,160
125
<2
126
...
<2
42
125
14

--
...
hlllltiat caolllaceut
...
...
...
...
...
...
...
...
...
42
1,042
04
...
...
Luti mhicillttm
...
...
...
...
...
...
...
...
...
<2
...
...
...

¡¡ililui parilfloma
251
...
...
...
...
...
...
...
...
...
...
<2
...
...
...
ScmhlUfllCtlt ?
...
...
...
...
...
...
...
...
...
42
...
...

...
...
Sltllull aedla
...
...
...
...
...
...
331
...
...
...
...
...
...
...
Oaktoat apeciea 11
...
...
...
...
...
...
...
...
...
375
1,134
2,750
375
...
...
12
...
...
...
...
...
...
14
250
42
...
...
...
...
...
IS
2,511
...

...
...
...
...
...
...
...
---
...
...
14
125
leaa 1 aeeda/a2
1,125
72,512
11,250
62,250
12,010
33,000
31,710
2,210
11,460
7,375
11,300
9,680
3,334
1,117
3,920
1 apeciea
11
3
1
6
5
1
4
4
7
16
13
14
4
5
6
ieiulU froi cor* eaaplea ID ci deep alth actual area aaapled corrected to ataadard refereace area of 1 i1.
Q\
O

Table 4
61
. Seed bank densities, species richness, and
Shannon-Weaver diversity index from Florida
wetlands and selected marsh studies from
temperate North America.
Mean #
seeds/m2
Number of
Species
Shannon-Weaver
Diversity Ji Source
Natural Systems. Florida
Bay Swamp
4,125
12
1.45
This study
Lake Kanapaha
SaccioleDis zone 156.000
38
2.64
Myers 1983
Amaranthus zone
28,000
17
1.72
Myers 1983
Echinochloa zone
30,000
13
0.98
Myers 1983
Pond zone
9,000
8
1.17
Myers 1983
Four Comers Marsh
Juncus-Pontederiazone
72,502
3
0.06
This study
Pasture Marsh
Juncus-Pontederiazone
41,250
4
0.26
This study
Unreclaimed Systems
Sanlan
Juncus-Polvaonum Marsh
62,250
6
0.30
This study
EichhorniaMarsh
12,040
5
0.86
This study
Reclaimed Systems
Four Comers Reclamation
Project
Mulched plot
33,000
4
0.05
This study
Planted plot
31,710
4
0.05
This study
Control plot
2,210
4
0.95
This study
Planted swamp plot
Clearsprings Reclamation
11,460
Project
4
0.30
This study
South Basin #1
7,375
16
2.03
This study
South Basin 42
11,300
13
1.92
This study
North Basin 9,880
Fort Green Reclamation Project
14
1.88
This study
Mulched, vegetated
3,334
4
1.11
This study
Mulched, unvegetated
1,877
5
0.84
This study
Unmulched
3,920
6
1.38
Thisstudy
Other Natural Systems
Iowa, Prairie
glacial marsh 20
-40,000
7-16
Not calculated van der Valk
and Davis (1976, 1978)
Ontario, Lakeshore
marsh 9
-20,000
31
Not calculated Keddy and
Reznicek (1982)
New Jersey, Freshwater
tidal marsh 6-
32,000
12-20
Not calculated
Leek and
Graveline (1979)

62
that the species richness and size of the seed bank appear to
decrease as the water depth increases in the Sacciolepis
zone-Amaranthus zone-Echinochloa zone-Pond zone (Table 4).
For the wetland samples cited from outside Florida, the
densities range from 6,000 to 40,000/m2, and for the three
natural systems sampled in this study, the range of densities
is 8,000 to 72,000/m2. The two marsh samples (Four Corners
natural marsh and pasture marsh) had densities of 41,000/m2
and 72,500/m2, respectively.
The unreclaimed wetland sampled, the Sanlan marsh, had
densities of 12,000/m2 and 62,000/m2 from the Eichhornia and
Juncus marshes, respectively. As with the Kanapaha samples,
seed bank size apparently decreases with depth (water depth
is more than a meter in the Eichhornia marsh). The Sanlan
samples, especially the Juncus-Polvqonum zone with 62,000/m2,
fall in the range of the natural wetlands already discussed,
thus representing some of the higher densities encountered.
This indicates that sizeable seed banks can develop in the
absence of any reclamation efforts in post-mining wetlands.
Wetland samples from reclaimed mine lands had a range of
1,800 to 33,000/m2, which is low to moderate by comparison to
natural wetland systems. Samples from the three basins at
Clearsprings ranged from 7,000 to 11,000/m2; at the Four
Corners project, the range was 2,200 to 33,000/m2. More
specifically, the treated plots had densities well within the
range of the natural systems: topsoiled (peat) marsh plot

63
(33,000/m2), planted marsh plot (31,000/m2), and swamp planted
plot (11,300/m2). The lowest density found at the Four
Corners project came from the control plot (2,200/m2),
indicating that seed bank establishment is facilitated by
reclamation efforts.
Samples from the Fort Green project had the lowest and
narrowest range of densities (1,800 to 3,900/m2), but it
should be remembered that this project is only in its second
growing season. Surprisingly, the lowest density value from
Fort Green, and for all samples, came from an unvegetated
topsoiled (peat) area with open water. This may be a result
of the vagaries of sampling; alternatively, the seed bank in
the peat at this spot may be dominated by short-lived seeds
or species that only germinate under flooded conditions (which
were not duplicated in this study) or the topsoil material
(peat) may have been stockpiled (as is known to have occurred
with some peat material at this site).
Species importance values. As an estimate of the overall
influence or importance of each species in the seed bank
survey, modified importance value were calculated from the
density and frequency totals (Table 5) The importance value
is calculated by adding relative density and relative
frequency for each species, where relative density as the
density of the species divided by the sum of all densities,
and where relative frequency is defined as the frequency of

64
Table 5. Seed bank density data from Table 3 summarized
across sites for species totals of density, relative density,
frequency, relative frequency, and importance value.
Density
Total
(mean #/m2)
%
Relative
Density
Sampling
Site
Frequency
%
Relative
Frequency
Importance
Value
Aster subulata
1,126
0.36
0.20
2.80
3.16
Baccharis
halimifolia
459
0.15
0.20
2.80
2.95
Carex sp.
125
0.04
0.07
0.95
0.99
Cvperus brevifolius
500
0.16
0.13
1.90
2.06
Cvperus sp.
2,209
0.70
0.20
2.80
3.50
Cvoerus rotundus 12.207
4.00
0.53
7.50
11.50
Cvperaceae ?
84
0.03
0.07
0.95
0.98
Echinochloa waiter!
125
0.04
0.07
0.95
0.99
Eclipta alba
958
0.30
0.27
3.80
4.10
Eupatorium
compositifolium
1,672
0.50
0.60
8.50
9.00
Graohalium
obtusifolium
84
0.03
0.07
0.95
0.98
Grasses, unknown #1
167
0.05
0.13
1.90
1.95
Grasses, unknown #2
42
0.02
0.07
0.95
0.97
Grasses, unknown #3
84
0.03
0.07
0.95
0.98
Grasses, unknown #4
417
0.13
0.20
2.80
2.93
Grasses, unknown #5
1,625
0.50
0.07
0.95
1.45
Grasses, unknown #6
126
0.04
0.13
1190
1.94
Hvdrocotvle
verticillata
42
0.02
0.07
0.95
0.96
Hypericum iwtilUffl
206
0.07
0.13
1.90
1.97
Junqus effUS.US 257,587
84.00
1.00
14.00
98.00
Juncus bufonius
209
0.07
0.20
2.80
2.87
mdwjgia Yiraata
8,499
3.00
0.47
6.60
9.60
Ludwjgia oalustris
376
0.12
0.13
1.90
2.00
Uidwiqia leptccarpa
294
0.09
0.13
1.90
2.00
Polygonum ounctatum
8,588
3.00
0.67
9.50
12.50
Ptilimnium
capillaceum
1,168
0.40
0.20
2.80
3.20
Ruroex verticillatus
42
0.02
0.07
0.95
0.97
Samclqg parviflorus
292
0.09
0.13
1.90
2.00
scrpBhulariaceas ?
42
0.02
0.07
0.95
0.95
stellaria madia
334
0.10
0.07
0.95
1.00
Unknown species #1
5,334
1.70
0.27
4.00
5.50
#2
376
0.10
0.20
2.80
2.90
#3
2,750
0.90
0.20
2.80
3.70
Column total 308,000
100.00
7.07
100.00
200.00

65
occurrence of the species divided by the sum of all species
frequencies. Both relative density and frequency were
connected. With this type of calculation, both relative
frequency and relative density are constrained to values
between 0 and 100 percent, which produces an importance value
for each species in the range 0 to 200.
The most striking aspect of the calculations was the
numerical dominance of soft rush (Juncus effusus), which
accounted for 84 percent of the germinating seeds in the
study. It was also the only species found in all samples,
yielding an absolute frequency of 1.0.
The 20 species of highest importance value account for
92.5 percent of the total importance value (see Table 6). In
fact, the four species of highest importance value soft rush,
smartweed (Polygonum punctatum), Cvoerus rotundus. and
Ludwiaia virqata account for 94 percent of the relative
density and 66 percent of the total importance value. These
four species can be considered the dominant species in this
study and serve in general to characterize the seed banks
sampled from central Florida.
Floristic similarity. Floristic similarity of seed bank
samples was measured using the similarity index of Czekanowski
for binary data. The index is defined as follows:
Czekanowski's index = 2a/(2a + b + c)
where a = species common to sites 1 and 2, b = species found
at site 1 but absent at site 2, and c = species found at site

66
Table 6. Twenty species with highest importance values (IV)
along with the relative density and relative frequency values
used to calculate the IV. All data taken from Tables 3 and
4.
% %
Relative Relative Importance
Species Density Frequency Value
Juncus effusus
Polygonum punctatum
Cyperus rotundus
Ludwigia virgata
Eupatorium compositifolium
Unknown 1
Eclipta alba
Unknown 3
Cyperus sp.
Ptilimnium capillaceum
Aster subulata
Baccharis halimifolia
Grass 4
Unknown 2
Juncus bufonius
Cyperus brevifolius
Ludwigia palustris
Ludwigia leptocarpa
Samolus parviflorus
Hypericum mutilum
84.00
14.00
98.00
3.00
9.50
12.50
4.00
7.50
11.50
3.00
6.60
9.60
0.50
8.50
9.00
1.70
3.80
5.50
0.30
3.80
4.10
0.90
2.80
3.70
0.70
2.80
3.50
0.40
2.80
3.20
0.36
2.80
3.16
0.15
2.80
2.95
0.13
2.80
2.93
0.10
2.80
2.90
0.07
2.80
2.87
0.16
1.90
2.06
0.12
1.90
2.02
0.09
1.90
1.99
0.09
1.90
1.99
0.07
1.90
1.97
185.00

67
but absent at site 1. The index has a range of 0 to 1.0,
where 0 represents complete dissimilarity and 1.0 represents
complete similarity.
There were few cases of high floristic similarity (Figure
10). One was a comparison between the two natural marshes
sampled and another between the Sanlan Juncus marsh and the
Four Corners mulched plot, both of which compare samples of
with low species richness. The other cases of high floristic
similarity are within-site sample comparisons, one from
Clearsprings and one from Fort Green.
The Clearsprings samples had the largest number of
species and had moderately high to high within-site floristic
similarity. The species assemblage at Clearsprings had
several unique or less frequently encountered species, includ
ing Aster subulata. Baccharis halimifolia. Eclipta alba. and
Ptilimnium capillaceum. The samples from Fort Green also
exhibited moderately high to high within-site floristic
similarity, largely due to three species (soft rush, Ludwiqia
virgata, and a species of Cvperus).
Many comparisons of low to moderate similarity are noted,
primarily because of the near ubiquity of soft rush and
smartweed in all samples (Figure 10).
Species diversity. Species richness and species
diversity were compiled from data from this study and from
Lake Kanapaha (Myers, 1983) (Table 4). Diversity was

Figure 10. Summary matrix of floristic similarity between seed bank samples.

BAY SWAMP
FOUR CORNER MARSH
PASTURE MARSH
SANLAN JUNCUS
SANLAN EtCHHQflNtA
FOUR CORNERS MULCHED
FOUR CORNERS PLANTEO
FOUR CORNERS CONTROL
FOUR CORNERS SWAMP
CLEARSPRINGS SOUTH BASIN I
CLEARSPRINGS SOUTH BASIN 2
CLEARSPRINGS NORTH BASIN '
FORT GREEN MULCHED VEGET
FORT GREEN MULCHED UNVEGET
PERCENT
FLORISTIC SIMILARITY
80-100 high
60 79 mod high
40-59 moderle
20 59 mod low
0 19 low
o\
o

70
calculated using the Shannon-Weaver diversity index, given as
H' and defined as
H' = (Pi In P0
where P¡ is the ratio of the number of individuals of the ith
species divided by the total number of individuals in the
sample. The value of H1 is influenced by two factors: the
number of species, known as species richness, and the equit-
ability with which the individuals of the population are
apportioned among the species. The greater the species
richness or the equitability the greater the value of H'.
The overall range of H' values was 0.05 to 2.64; the
lower value was from the mulched, vegetated plot at Fort Green
and the highest from the Sacciolepis-zone at Lake Kanapaha.
The latter sample also had the highest seed density
(156,000/m2) and the highest species richness (38).
The samples with the greater number of species typically
had H1 values in the upper range (see Table 4) The most
diverse natural wetland samples came from Lake Kanapaha and
the bay swamp, while the highest diversity in the mined
wetlands group was in the Clearsprings samples. In several
cases (Four Corners natural marsh, pasture marsh, Four Corners
mulched plot, Four Corners planted plot, and Sanlan
Juncus-zone. the seed bank had relatively few species and was
dominated numerically by soft rush. This situation more or
less defined the low end of the H'
range.

71
Seed bank samples from all but the youngest sites in the
post-mining landscape fall within or just below the range of
densities and species diversity found in natural wetlands of
Florida, Iowa, New Jersey, and Ontario. The indications from
the results in this study are that it is possible for nature
to reestablish a seed bank of approximately the same size and
diversity as that occurring in some natural marshes, such as
with the Juncus-Polvgonum marsh at Sanlan (30 years old). The
time required for the seed bank to become a "reasonable
facsimile" of a natural marsh as yet may be undefined. The
results at Clearsprings indicate that modest sized seed banks
with higher diversity can develop in 4 years with little
actual marsh reclamation. With some reclamation efforts, seed
banks that compare very favorably in size with natural marshes
can develop in 5 years, as demonstrated at Four Corners.
The seed banks in some of the post-mining wetlands do not
appear to be different in size and species composition from
the natural marshes sampled in this study. However, the actual
vegetation present is not always as diverse, dense, or well
developed, except in cases where muck (topsoil) from a donor
wetland was applied. As an example, the results of line-
intercept transects in mucked and unmucked areas of the marsh
at Fort Green showed that the mucked areas to have 100 percent
cover, while the unmucked areas had less than 30 percent
cover.

72
Marsh Transect Study
Water levels and hvdroperiod. Daily water levels in the
Fort Green wetland were summarized as mean monthly values for
the period of the study, August 1982 to December 1985 (Figure
11) Evident trends include the typical annual hydroperiod
cycle and the drought that began in late 1984 and continued
through late summer of 1985.
The typical annual hydroperiod cycle began with low water
in early winter followed by a rise in late winter or early
spring and a spring peak. The cycle continued with a summer
decline, a late summer peak, and a fall decline. With the
exception of the 1985 drought cycle, the annual hydroperiod
in the basin has typically varied about 0.3 m between lows of
approximately 36.42 m msl to peaks of about 36.67 m msl.
From the fall of 1984 through the spring 1985 a drought
occurred that was unrelieved by spring rains. Water levels
in the basin declined steadily from August 1984 to June 1985,
when they reached a monthly low of 35.37 m msl. The late
summer rains of 1985 brought the water level up to the typical
late summer peak by August.
The transect elevation data were used to generate
individual transect profiles (see Figures 12 and 13) Four
of the transects (97, 115, 125, and 130) began at elevations
between 36.06 and 36.27 m, while transect 105 started at a
lower elevation (35.60 m msl) and transect 139 started at a

Figure 11. Hydrograph of surface water elevation in Fort Green wetland based on average
monthly values for the period August 1982 through December 1985.
-j
u

74
O 30 60 90 120 150 180
Trancl Distance (m)
0 30 60 90 120 150 180
Transact Distance (m)
37.0
1 365
E,
| 36 0
35.5
MuckTre
itmentZc
me
TF
ANSEC
T 139
1
0 30 60 90 120 150 180
i(m)
Figure 12. Elevation profiles of marsh transects 97,
139 with muck treatment zones indicated.
105 and

75
37.0
1 36.5
E
36.0
35.5
37.0
| 36.5
E
35.5
s/
TF
ANSEC
T 115
30 50 90 120 150 180
i(m)
A
a y
y
TF
ANSEC
)T 125
I l
30 60 90 120 150 180
0 30 60 90 120 150 180
Transact DWanca (m)
Figure 13. Elevation profiles of marsh transects 115. 125,
and 130.

76
higher elevation (36.45 m msl). Four of the transects ended
at approximately the same elevation of 3 6.60 m msl. The
remaining two transects (130 and 139) ended at approximately
36.80 m msl.
The daily basin water levels for the period August 1982
to December 1985 were used to generate a depth exceedance
relationship (Figure 14) showing percent of the time a given
elevation was inundated. The graph shows a 1.2 m variation
in water level during the study period; elevations below 35.51
m msl were inundated 100 percent of the time and areas above
36.73 m msl were never inundated. The curve slopes gently in
the 80 to 100 percent inundation, range which covers a
relatively broad range of elevations from 35.51 to 36.33 m
msl. The 70 to 80 percent inundation zone covers a relatively
narrower elevation range (36.33 to 36.45 m msl). The slope
of the depth exceedance curve is fairly steep in the 0 to 70
percent inundation range (elevation 36.33 to 36.73 m msl) then
flattens at the maximum inundation of 36.73 m msl.
Emergent Macrophytes. The changes in cover of
pickerelweed (Ppntederia cordata) and cattail (Tvpha latifolia
and T. dominqensis) on each of the six transects through each
of the eight sampling periods were summarized from the line-
intercept data. Pickerelweed and cattail were used because
each was initially the dominant perennial emergent macrophyte
in the mucked and unmucked zones, respectively. This

Figure 14. Depth exceedance curve for Fort Green wetland indicating the percent
inundation for each elevation over the time period August 1982 through December 1985.
-j

78
dominance was consistent throughout the study (see detailed
vegetation data in Appendix B).
The time series of cover changes for the two taxa
(Figures 15a through 15f) illustrate several aspects of the
biology of the two species and differences in the marsh
community development in mucked and unmucked areas.
Pickerelweed became well established in the mucked zones of
transects 97 and 105, but failed to reach the same level of
development on any of the other four transects, including
mucked transect 139. Conversely, cattail became well
established on the overburden transects but lagged in
colonizing those areas with well established stands of
pickerelweed (transects 97 and 105).
Also, through the first few sampling periods, the
sequence of stand establishment is evident for both taxa:
(1) initial establishment of individual plants or clumps, (2)
expansion of initial clumps, and (3) consolidation of clumps
into larger patches or stands. Following the consolidation
phase, most of the large clumps remained stable up to the
drought of 1985. After the establishment phase, some movement
and adjustment to other areas of the transect took place,
especially in the case of cattail. This sequence of
establishment is well demonstrated on transects 97 and 105 for
pickerelweed (Figures 15a and 15b) and transects 115, 125,
130, and 139 for cattail (Figures 15c, 15d, 15e, and 15f) .
One particular difference between the two taxa is the vagility

Figure 15. Percent cover by Pontederia cordata and Tvnha latifolia on marsh transects
at Fort Green in fall 1982; spring, summer, and fall 1983; spring, summer and fall 1984;
and summer 1985 at (a) transect 97, (b) transect 105, (c) transect 139, (d) transect
115, (e)transect 125, and (f) transect 130.

Ponlederia cordata
Fall 1082
Spring 1983
Summar 1963
FaN 1983
Spring 1964
Summar 1984
FaB 1984
Summar 1985
Typha latHoUa
Transad 97
1
1. ^
L
Dill
ri
i
i 1 1
60 90 120 ISO
Transad Dtstanca (m)
o
30
180

Fail 1982
Spring 1963
Summer 1963
Fall 1963
Spring 1964
£,ooin
U
too n
100
Summer 1964 $
J
Fall 1964
Summer 1985
100
Pontederia cordata
Traneect 105
4L
1
n
-L-rLj-V-
100
J.
*! 1
JZ
11
15 30 45 60 75 SO 106 120
Traneect Distance (m)
0
Typha latttolla
Transect 105

, T ,
r.zL
i ~i r I I | |
30 45 60 75 80 105 120
Transect Distance (m)
o
15

100
Fa> 1982
Spring 1983
o
100
I
o
100
Summer 1963
I
o
100
FaM 1963
Spring 1984
Summer 1964
I
o
10
J
0
100
I
0
100
FaM 1984
I
0
100
Summer 1985
I
Pontederta corrala
Tranaecl 139
Ti la
Ilk.
30 45 60
Tranaecl Distance (m)
o
15
75
90
Typha iatiloMa
Transect 139
30 45 60
Transect Distance (m)
o
15
75
90

Pontederia cordata
Transact 115
Fall 1982
Spring 1963
Summer 1983
Fall 1983
Spring 19M
Summer 1964
FaM 1984
Summer 1985
Tranaect Distance (m)
Tvpha latHoUa
Tranaect 115
Tranaect Distance (m)
oo

Ponlederia cordata
Transact Distance (m)
Typha latttoMa
Transact 125
03
4s

Pontederia cordata
FaM 1962
Spring 1963
100
Summarises |
o
!00
FaM 1963
Spring 1964
o
10
I.
/ 100
o
0
Summer 1964
FaM 1964
100
Summer1965 k
J .
i r-
i 1
15 30 45 60 75 90
Transect Distance (m)
Typha latifolia
Transect 130
1 1 1 1
n n [
1
1 i i
n moli
D C=L
O
0 15 30 45 60 75 90
Transect Distance (m)
oo
en

86
of the propagules. Cattail has a very small, wind-dispersed
seed? pickerelweed has a heavier, water/animal-dispersed
fruit. On several of the transects, cattail was able to
colonize new areas as they became available with the falling
water levels of the drought of 1985. Cattail appeared more
successful at expanding into open habitat than pickerelweed,
but other taxa were equally opportunistic, especially bulrush
(Scirpus californicus) and dogfennel (Eupatorium
capillifolium).
Major changes in the littoral zone vegetation resulted
from the drought. The overall species richness and total cover
values within the wetland were within the range found in
previous periods, but the manner in which the cover was
apportioned over the various taxa was significantly different.
For both the topsoiled and overburden areas, the cover of many
common species declined and dramatic increases in cover were
shown by other taxa, especially dogfennel and bulrush.
Dogfennel increased profoundly in cover percentages (25
percent and 18 percent for muck treatment and overburden areas
respectively) (Table 7) especially in the deeper areas of the
wetland as the water levels receded. At the peak of the
drought, most of the area that typically had standing water
was vegetated with a well established, monospecific stand of
dogfennel by April of 1985. The timing of the dogfennel
germination means that the seeds would have had to have been
lying dormant in the substrate; as the water level receded,

87
Table 7. Percent cover of Eupatorium capillifolllum and
Scirpua callfornicus on muck treatment and overburden
transects, Fort Green marsh,eight sampling periods between
fall 19S2 and summer 1985.
Eupatorios capillifoliua Scirpus callfornicus
Sampling
Period
Muck
Transects
Overburden
Muck
Transects
Overburden
Fall 1982
6



Spring 1983
0.2



Summer 1983
0.4
0.1


Fall 1983
0.1
<0.1


Spring 1984
0.1
0.2

0.2
Summer 1984
0.3
0.2
0.2
0.3
Fall 1984
1
0.3
0.9
0.9
Summer 1985
25
18
6
9

88
the dogfennel seedbank responded and a complete cover
developed.
Bulrush also increased in cover at the north end of the
basin, as seen in 1985 results from transects 125, 130, and
139. As with dogfennel, the increase occurred in normally
flooded areas lacking established emergent vegetation. The
area of bulrush invasion was also a site of noticeable
invasion by Saaittaria lancifolia and dogfennel. These areas
showed little to no invasion by cattail, which was well
established in the vicinity and had been spreading
vegetatively for the previous two seasons. Bulrush was able
to colonize and establish in an area that appeared to be ideal
for cattail invasion.
The transect specific elevation profiles and inundation
frequencies were used to compare the zones of establishment
of cattail and pickerelweed (Table 8) The two taxa do occupy
roughly the same zone within the wetland based on the patch
establishment (Figures 15a through 15f) from approximately
elevation 36.33 to 36.58 m msl and with an inundation range
of 40 to 80 percent. The results from transect 105 are
particularly interesting because the mulch was spread in
deeper areas, down to elevation 3 5.51 m msl, that were
permanently flooded. These deepwater stands were neither
invaded nor encroached upon by cattail during the study
period. They were also not ephemeral in nature, remaining
constant throughout the study although they showing similar

Table
. Summary of transect distance, elevation range, and inundation frequency of
establishment zones for Pontederia cordata and Typha sp. on marsh transects
at Fort Green wetland reclamation demonstration project; and summary of
transect distance, elevation range, and inundation frequency of muck treatment
zones on transects 97, 105, and 139.
luck Treataeat Traaiecta Orerburdea Soil Traaaocta
97
10S
119
US
125
130
Poatederia cordata
Iaitial ippearaaca (dlataace )
90 to ISO
0 to 104
67 to 07
52 0 02
225
72
litabliikaeat loaa {dlataace )
90 to ISO
0 to 104
07 to 01
21 to 04
225 0 390
72
lleratioa laaia ( ail)
36.11 to 36.33
3S.S0 to 36.39
16.50 to 30. 00
36.36 to 36 45
16.4 0 30.51
30 40
Iaiadatloa Frequeacj
00 to 850
7S to 1000
0 to 350
70 to 750
00 to 750
750
Tjpba ap.
Iaitial ippearaace (diataace a)
US to 100
75 to US
70 1 00
45 to 00
75 to 120
02 to 05
latabllihaeat loaa (dlataace a)
9S to 12S
OS to US
0 to 01
32 to 05
49 to 122
0 to 62
lleratioa laife (a aal)
36 27 to 36 36
36 10 to 30.42
30.45 to 16.50
36.40 to 30.50
30 10 to 30.50
10.30. to 30.50
Iaoidatioa Irt(itac)
000
70 to no
45 to 700
00 to 700
40 to 000
50 to 000
luck Treataeat Area
Traataeat loaa (dlataace a)
90 to 100
S to US
50 to 00
lleratioa laafa (a aal)
36.10 to 10.OS
35 69 to 30.19
36 45 to 30.85
Iauadatioa Frequeacj
TO to 0S0
70 to 9S0
0 to 700
03
VO

90
drought response. This indicates that macrophytes like
pickerelweed can become established in deep water areas and
muck application should be extended down to elevations with
an average depth of flooding of up to 1 m or more.
Large stands of pickerelweed developed only in the muck
treatment areas. Though it produced large numbers of seeds,
pickerelweed did not spread far from the areas of initial
establishment during the first four growing seasons.
Upland Succession Plots
Seed Germination and Survival
The experiment was originally designed as a nested
analysis of variance with a balanced design (i.e., equal
replications for each treatment). A sampling mistake during
the second weeding event (May) changed this plan, when plot
15 was weeded instead of plot 18. The error was not
discovered until the third weeding (June), at which time it
was decided to continue weeding plot 15. This change created
some difficulties as to the treatment status of plots 15 and
18. To incorporate plots 15 and 18 into the analysis, the
analysis of variance (ANOVA) for each species was carried out
using two different assignments for the plots: one analysis
with plot 15 assigned to weeded treatment and plot 18 dropped
and a second analysis with both plots dropped. Analyzing the
data following the original plot assignments (15 to enhanced

91
colonizer and 18 to weeded) was clearly inappropriate, as plot
15 could be no longer be considered as part of the enhanced
colonizer treatment after it was weeded, but a simpler
solution seemed to be to drop plots 15 and 18 from the
statistical analysis altogether. Although an unbalanced
design may result, any problems of equivocation over the
treatment status of plots 15 and 18 are eliminated. An ANOVA
configuration in which plot 15 is assigned to the weeded
treatment and plot 18 is dropped is also a fairly clearcut
case. As plot 15 was weeded during the later part of the
growing season, the seedlings were growing under weeded
conditions beyond the germination stage.
The seed plots yielded information on germination, the
survival of the germinating seeds, and the growth of the
surviving seedlings. Total germination was estimated with
data from the two sampling periods in March and October 1984
(Table 9). Because the location of each seedling in the plot
was recorded at the time of sampling, the fate of any given
seedling could be followed through time. Thus, the mortality
of germinating seedlings could be estimated and an idea
developed of the phenology of germination (Table 10 and Figure
16) .
Overall, 20 percent of the seeds planted did germinate
and percent of those germlings survived through the first
growing season. The individual species showed a full range
of response in both germination and survival. Magnolia was

Table 9. Seed germination in Gardinier seed plots as measured by seedling counts in
March and October 1984 along with the total cumulative germination. Data
given by species and treatment.
Celtio laeiifata
Lieeidaebar atiracifloa Carta i labra
Sabal oalaetto
Oaercua
laliolia iraaditlora
Ml)
Treataeat
lid plot
Can lot lie
trek Oct Total
Ciialatiie Coaulatite
larck Oct Total lard Oct Total
Caaalatlte
lard Oct Total
Cuaolatiie
lard Oct Total
Coialatlto
lard Oct Total
Coialatlto
lore! Set Total
fikaiced
1
(
¡1
Coloiiied
11
14
15
+-li if
i H n
41
51
1} 11 43 0 t
MII
Heeded
1
5
1
11
t 3
1 5
3 t
15 1
1
1
6
It
2
3
i
0
3
1
1
2
5
4
1
1
2
4
3
2
4
6
a
3
4
1
1
1
1
1
|
f
It
13
11
f
11
11
11
13
15
IT
21
41
41
42
21
50
45
41
31
0
0
0
0
0
1
I
t
0
t
0
1
22 51
21 S2
21 (I
41 15
fl
|
11
31 21
It
11
5
14
11
20
21
0
41
40
ft
1ST
110
0
1
0
111 24f
231
Leioaed
4
7 0
7
2
1
3
1
3
4
0
5
5
If
35
42
0
0
0
26 44
fl
1
t 5
11
0
t
0
1
4
4
t
1
t
11
41
4i
0
0
1
21 51
11
It
S t
12
1
t
0
1
5
6
I
1
1
11
42
41
0
0
0
It 5f
f9
12
14 2
14
1
1
3
1
1
4
t
1
1
2(
11
51
1
1
1
4f 53
It
36 11
44
5
1
(
t
13
It
1
21
21
11
Iff
190
0
0
I
III 219
211
135 41
154
IT
If
41
12
fl
11
0
115
15
2TT
S47
131
0
0
0
111 Iff
1121
VO
K>

Table 10. Summary of germination and survival results from Gardinier seed plots. The
percentage survival is here defined as the percentage of all seeds that
germinated which survive to the end of the growing season.
Mill UuUutor £uu Sibil imoli totrcii ToUl
Cuiolatlie Sorilial Caanlatlie Surilial Coaulaliie Survival Cuaalative Survival Cuiulative Survival emulative Survival emulative Survival
Treatueit leraiaatioa leruiiatloa feniiatioi (eriiaatiou feriluatiou lenliatloi (eraluatiou
i m > m i m m i m id o m i to i m i 10 i it) i to i id i m
Iibauced
42
(21)
1
(10
11
(10
2 (10
If
( 0
10
(62)
22
111)
22 (100)
0
0
If 4
(91)
141 (07)
2S7 IOS (72)
Coloulied
22
(10
S
(10
It
(0
1 (SO
24
(12)
11
(TS)
20
(10)
20 (100)
0
0
20S
10)
171 (01)
297 222 (7S)
Needed
](
(10
21
(SO
14
(7)
S (10
21
(US)
20
(11)
40
(20)
40 (100)
0
0
100
(4S)
167 (91)
291 24f (04)
Lefuaed
44
(22)
1)
(20
(
(1)
1 07)
U
I 0
11
(72)
21
(11.S)
21 (100)
0
0
190
(47)
Iff (07)
201 216 (77)
1S4
00
47
(10
49
(0 1
if (10
0
(10
0
(7S)
10S
(ID
10S (100)
0
0
739
(40
647 (07) 1120 (20) 069 (77)
VO
u>

Fiqure 16. Number of germinated seeds on tree
Seeds planted in fall of 1983 and plots sampled
species planted at Gardinier plots,
in spring and fall of 1984.

Cumulative Number of Seeds Germinated
Motete Oc lobar
o
O
E
3
E
3
o
200-1
too -
Carya globro
200-,
Magnolia grandiflora
October
March
too-
March
OcMhar
Dtd Individuals
Uv Individual
200
J9
m
a
* 100
o
Liquidombar
slyraciflua
March
October
200 n
a
a
1
3
X
- IOO-
3
c
Sobol palme Mo
October
VO
m

96
unique in that no seeds germinated regardless of plot or
treatment. Sweetgum had only 6 percent germination and only
33 percent of those survived. Sugarberry had 19 percent
germination, but only 30 percent survival.
The other three taxa had much higher survival rates.
Hickory had 10 percent germination with 75 percent survival.
Germination in cabbage palm was 13 percent with 100 percent
survival. Oak had both high germination (46 percent) and high
survival (87 percent). Because of the difficulty in
accurately distinguishing between young laurel oak and young
live oak seedlings, the two are treated as a single taxon.
The species showed interesting combinations of
germination phenology and survival. The majority of
sugarberry and sweetgum germination occurred before the March
sampling. Additional seeds germinated between March and
October, but mortality in both cases was so high that the
total number of live seedlings was lower in October than in
March (see Figure 16) Germination of hickory and oak had
germination occurred throughout the growing season, with a
larger number of seeds germinating after March. For these two
taxa, the germination phenology combined with low mortality
resulted in a greater number of live seedlings at the second
sampling period than the first. Finally, cabbage palm
demonstrated a different germination pattern, with all
germination occurring after March (see Figure 16).

97
Another way of analyzing the seed germination and
survival data is to compare at the end of season survivors as
a proportion of the seeds planted. The data on seedling
survival from the experimental plots were converted to
percentages for analysis. It is known from statistical theory
that proportions or percentages have binomial rather than
normal distributions, and that the deviation from normality
is greatest for small and large values. The data can be
transformed, however, to obtain a distribution that
approximates normal. The square root of each percentage was
transformed to its arcsine to give an underlying distribution
that is nearly normal. The percentages were so transformed
(Table 11) before conducting the ANOVA.
For the case where the data are summed over species
within each plot the results of two ANOVAs are similar (Table
11a) When data from plots 15 and 18 are neglected in the
analysis, the means for the weeded, natural colonizer, and
enhanced legume treatments are not significantly different,
but the enhanced colonizer treatment mean is lower and
significantly different from the other three. When plot 18
is dropped and plot 15 is assigned to the weeded treatment the
result is essentially the same.
The plot-by-plot survival results can also be examined
for individual species. The analysis assumes that there are
no interactions between species. Because this assumption
cannot be made for multi-species seed mixes any inferences

98
Table 11. Comparison of mean percent germination/survival for
four experimental treatments (weeded, natural
colonizers, legume, enhanced colonizers) using arc
sine transformed data. Means compared following
an ANOVA, using Duncan's multiple range test.
Means with the same letter are not significantly
different (p =.05).
Table 11a. All species summed
Treatment Means
Plot Assignments
PR>F
Weeded
Natural Enhanced
for ANOVA
(ANOVA)
Legume Colonizers
Plots 15 & 18
25.017
23.567 22.857 19.027
Neglected
.0079
A
A A
B
Plot 15 Weeded,
25.510 23.567
22.857 19.027
18 Neglected
. 0031
A A
B
B
C

99
Table lib. Pignut hickory (Carya glabra)
Treatment Means
Plot Assignments
for ANOVA
PR>F
(ANOVA)
Weeded
1
Natural
Enhanced
Legume Colonizers
Plots 15 & 18
Neglected
NS
16.080
A
17.390
A
14.292
A
10.897
A
Plot 15 Weeded,
18 Neglected
NS
16.167
A
17.390
A
14.292
A
10.897
A

100
Table 11c. Sugarberry (Celtis laevigata).
Treatment Means
Plot Assignments
PR>F
Weeded
Natural
Enhanced
for ANOVA
(ANOVA)
Legume
Colonizers
Plots 15 & 18
17.693
8.892
12.420
5.847
Neglected
.0772
A
A
A
B
B
B
Plot 15 Weeded,
18.387
8.892
12.420
5.847
18 Neglected
.0297
A
A
B
B
B

101
Table lid. Sweetgum (Liouidambar stvraciflua)
Treatment Means
Plot Assignments
for ANOVA
PR>F Weeded
(ANOVA)
Natural
Enhanced
Legume Colonizers
Plots 15 & 18
7.863
11.057
2.992 4.7
Neglected
NS A
A
A A
Plot 15 Weeded,
6.217
11.057
2.992
4.7
18 Neglected
NS
A
A
A
A

102
Table lie. Oak (Ouercus)
Treatment Means
Plot Assignments
for ANOVA
PR>F Weeded Natural Enhanced
(ANOVA) Legume Colonizers
Plots 15 & 18
Neglected
42.127 41.105 39.645 33.930
.0604 A
A A
B
Plot 15 Weeded,
18 Neglected
42.127 41.105 39.645 33.930
0347
B

103
Table Ilf. Cabbage palm (Sabal palmetto).
Treatment Means
Plot Assignments
PR>F
Weeded
Natural
Enhanced
for ANOVA
(ANOVA)
Legume Colonizers
Plots 15 & 18
25.833
18.155
10.410
11.910
Neglected
.0841
A
A
B
B
B
Plot 15 Weeded,
27.040
18.155
10.410
11.910
18 Neglected
.0300
A
A
B
B
B

104
regarding the results will lack some degree of statistical
rigor. In spite of this inability to meet all assumptions
required by theory, the analysis by individual species may
provide valuable insight to the hypotheses being tested that
might otherwise be ignored. Therefore, an ANOVA was run on
the transformed survival data for each species. Magnolia was
not included in the analysis because none germinated in any
plots. The results are again presented in two ways depending
on how plots 15 and 18 were assigned.
Hickory (Table lib) and sweetgum (Table lid) are the
simplest cases; no significant differences were seen among any
of the treatment means in either of the two ways plots 15 and
18 were assigned.
Sugarberry (Table 11c) and oak (laurel oak and live oak
summed) (Table lie) showed similar patterns in response to
two different ANOVA situations and both had significant
differences in at least some of the treatment means. When
plots 15 and 18 were neglected, the two taxa exhibited
slightly differing results. For sugarberry, the weeded,
enhanced legume, and natural colonizer means were not
significantly different, but weeded and enhanced colonizer
means were. For oak, the weeded, natural colonizer and
enhanced legume means were not significantly different from
each other but were all different from the enhanced colonizer
mean, which was also lower.

105
In the second ANOVA configuration, in which plot 15 was
assigned to the weeded treatment and plot 18 was ignored,
sugarberry and oak showed similar but not identical patterns.
The means were not significantly different for sugarberry for
the weeded and enhanced legume treatments or among the legume,
natural colonizer, and enhanced colonizer treatments. The
weeded and enhanced means were different, with the enhanced
colonizer value the lower. For oak, the weeded, natural
colonizer, and enhanced legume treatment means were not
different from each other and all were significantly different
from and higher than the enhanced treatment mean.
Cabbage palm exhibited significant differences between
some treatment means, but the results were the same for both
ANOVA configurations (Table Ilf). The means for the weeded
and natural colonizer treatments were not significantly
different, and the natural colonizer, enhanced colonizer, and
enhanced legume means were not significantly different, but
the weeded mean was different from and higher than the legume
mean.
Height Growth in Seed Plots
Height growth data from the seed plots were analyzed in
the same manner as the survival data for each individual
species and for the sum of all species (Table 12). When the
height data were summed over species, the ANOVA results were
the same in both combinations of assigning plots 15 and 18

106
Table 12. Comparison of mean seedling height growth
four experimental treatments (weeded,
colonizers, legume, enhanced colonizers),
compare following an ANOVA, using Duncan's
range test. Means with the same letter
significantly different (p <.05).
Table 12a. All species summed
(cm) for
natural
. Means
multiple
are not
Treatment
Means
Plot Assignments PR>F
Weeded Natural
Enhanced
for ANOVA (ANOVA)
Legume Colonizers
Plots 15 & 18
Neglected
.0001
7.78 6.4
A
6.26
5.8
B
B
B
Plot 15 Weeded,
18 Neglected
.0001
8.02 6.4
A
6.26
5.8
B
B
B

107
Table 12b. Pignut hickory (Carva glabra)
Plot Assignments PR>F
for ANOVA (ANOVA)
Treatment Means
Weeded Natural Enhanced
Legume Colonizers
Plots 15 & 18
Neglected
NS
6.25 5.61 5.61 5.17
AAA A
Plot 15 Weeded,
18 Neglected
NS
5.87 5.61 5.61 5.17
A A A A

108
Table 12c. Sugarberry (Celtis laevigata).
Treatment Means
Plot Assignments PR>F
for ANOVA (ANOVA)
Weeded Natural Enhanced
Legume Colonizers
Plots 15 & 18
Neglected
NS
8.5 7.0
A A
6.5 8.0
A A
Plot 15 Weeded,
18 Neglected
NS
8.3 7.0
A A
6.5 8.0
A A

109
Table 12d. Sweetgum (Licmidambar stvraciflua)
Treatment Means
Plot Assignments
PR>F
Weeded
Natural
Enhanced
for ANOVA (ANOVA)
Legume Colonizers
Plots 15 & 18
6.0
5.0
4.0 4.5
Neglected
NS
A
A
A A
Plot 15 Weeded,
o

VO
o

in
4.0 4.5
18 Neglected
NS
A
A
A A

110
Table 12e. Ouercus.
Treatment Means
Plot Assignments
PR>F
Weeded
Natural
Enhanced
for ANOVA (ANOVA)
Legume Colonizers
Plots 15 & 18
7.81
6.26
6.19
5.63
Neglected
.0011
A
B
B
B
Plot 15 Weeded,
8.17
6.26
6.19
5.63
18 Neglected
.0001
A
B
B
B

Ill
Table 12f. Cabbage
palm
(Sabal
palmetto).
Treatment
Means
Plots 15 & 18
Neglected
NS
8.14
A
8.65
A
7.09 7.67
A A
Plot 15 Weeded,
18 Neglected
NS
8.23
A
8.65
A
7.09 7.67
A A

112
(Table 12a). In both cases, the F-value was significant
(p =.0001) and the mean height growth for the weeded
treatment was significantly different and higher than the
other three treatment means. There were no significant
differences among the means for the natural colonizer,
enhanced legume, and enhanced colonizer treatments. Assigning
the height growth data by individual species reveals an
interesting trend. Generally, the oak results mimicked the
results from the combined species data, while hickory,
sugarberry, sweetgum, cabbage palm, and magnolia all had
similar results as a group that were quite different from oak.
As in the case with height data summed over species, the
oak data had a highly significant F-value for both ANOVA
regimes. The weeded treatment mean was found to be
significantly different from and higher than the other three
treatment means, which were not significantly different from
each other (Table 12e) For the most part, the growth
response of the other four species (hickory, sugarberry,
sweetgum, and cabbage palm) were similar. In all cases, no
statistically significant differences were seen among the
treatment means (Tables 12b, 12c, 12d, and 12f).
Height Growth in Transplant Plots
The three species (sweetgum, live oak, and cabbage palm)
were first treated separately in the analysis under the
assumption that the 1-m spacing between seedlings would

113
prevent any interaction between species. Analysis was also
performed summing growth data for all three species together.
The ANOVA of the height growth data for each of the three
species showed a significant F value (p < .05) (Table 13),
indicating that at least one of the treatment means was
significantly different from the rest. Duncan's multiple
range test was used to determine which treatment means were
significantly different (Table 13).
For sweetgum seedlings, the mean height growth for the
weeded treatment was significantly different and higher than
the mean height growth of the other three treatments, and
there was no significant difference among the means for the
natural colonize, enhanced colonizer, and enhanced legume
treatments.
The mean height change for the live oak seedlings was
also significantly different for the weeded treatment. The
live oak seedlings in the weeded plots had a higher mean
growth change over the first growing season. The analysis
again showed no significant difference among means in the
other three treatments.
The Duncan's multiple range test for the cabbage palm
data yielded different results. Weeded, enhanced legume, and
natural colonizer treatments were not significantly different
from each other and neither were the natural and enhanced
colonizer treatments. The weeded and legume treatment means

114
were both significantly different from and higher than the
enhanced treatment mean.
When growth data were summed over species, the results
were the same as for sweetgum and live oak. The mean for the
weeded treatment was significantly different and higher than
the means for the other three treatments, which were not
significantly different from each other.
Mound-Building Ants
Mound Survey
The field surveys showed mound densities of 560/ha,
2,070/ha, and 2,100/ha for the 1-, 2-, and 5-year old sites,
respectively. Average mound volumes were 600 cm3, 2,420 cm3,
and 1,250 cm3 for the 1-, 2-, and 5-year old sites,
respectively.
Plant Growth Study
The results of the vasey grass growth test (Table 14)
show a uniform trend of significantly different and higher
growth rates for the plants grown on mound soil for all three
sites. A statistically significant growth enhancement was
found in all three cases for the aboveground, belowground, and
total plant biomass. For all comparisons, the mean biomass
value for the mound samples was higher and significantly
different (p < .01).

115
Table 14. Results of vasey grass growth bioassay on mound and
non-mound soils from 1-, 2-, and 5-year old sites.
Site
(age)
Seedling
Growth
Parameter
Mean
Mound
Soil
Non-mound
Soil
P
Tiger Bay
(1 year)
Below ground
biomass (g)
0.242
0.139
. 002
Above ground
biomass (g)
0.386
0.162
.0005
Total
biomass (g)
0.626
0.301
. 0006
Fort Green
(2 year)
Below ground
biomass (g)
0.233
0.145
.0003
Above ground
biomass (g)
0.226
0.153
.004
Total biomass
(g) 0.459
0.298
.0004
Clearsprings
(5 year)
Below ground
biomass (g)
0.284
0.172
.0001
Above ground
biomass (g)
0.308
0.160
.0003
Total
biomass (g)
0.592
0.332
.0001

116
The sweetgum growth bioassay also showed a uniform growth
enhancement on the mound soil (Table 15) For all growth
parameters measured (stem biomass, root biomass, leaf biomass,
total biomass, leaf area, and stem height), the mean for the
mound soil was significantly different (P < .05) and higher
than the non-mound mean. For biomass and leaf area growth
parameters, the means for the seedlings grown on the three
mound soils were at least twice those of the seedlings on the
non-mound soils.
Chemical Soil Analyses
Chemical analysis of mound and non-mound soils highlights
some differences in several of the chemical parameters
assayed. Because the sampling technique used was paired
samples, results are presented as mean differences of each
pair with the non-mound value subtracted from the mound value
(Table 16) Positive differences connote higher values for
the mound samples.
pH values exhibited a wide range at each of the three
sites but tended to be circumneutral as compared to the
characteristically acid soils native to the region. The mean
difference of pH values between pairs was not statistically
different at any of the three sites.
Calcium levels showed no statistically significant
differences between sample pairs from any of the three sites.
For magnesium and manganese, no statistically significant

117
Table 15. Results of sweetgum growth bioassay on mound and
non-mound soil from 1-year old site.
Seedling Growth
Parameter
Mean for
mound soil
(n=5)
Mean for
non-mound soil
(n=6)
P
Stem biomass (g)
0.41
0.14
. 0001
Root biomass (g)
0.99
0.42
.0002
Leaf biomass (g)
0.34
0.17
. 0003
Total biomass (g)
1.73
0.67
. 0001
Leaf area (cm2)
89.68
44.30
. 0003
Stem height (cm)
13.4
9.68 <
.03

118
Table 16. Results of paired-difference comparisons between
mound and non-mound soils for selected chemical parameters
from Tiger Bay (1 year-old), Fort Green (2 year-old) and
Clearsprings (5 year-old) reclamation areas.
Difference
(Mound -
Non-mound)
Site
Age
(Years) Mean Error
Range P
Calcium
1
315.0
227.4
- 250 to 1250
NS
(mg/X)
2
-198.5
343.5
-1370 to 970
NS
5
-93.3
366.7
-510 to 340
NS
Magnesium
1
108.3
121.8
-90 to 700
NS
(mg/X)
2
-38.3
51.6
-260 to 90
NS
5
48.3
15.1
-10 to 100
.05
Manganese
1
1.2
0.79
0.0 to 5.0
NS
(mg/X)
2
0.0
0.26
- 1.0 to 1.0
NS
5
2.5
0.5
2.0 to 5.0
.01
Potassium
1
94.2
25.8
37 to 206
.05
(mg/X)
2
55.5
9.9
29 to 86
.01
5
79.3
14.5
52 to 141
.01
Sodium
1
28.3
10.7
8 to 72
.01
(mg/X)
2
24.8
9.3
4 to 54
.01
5
7.0
2.0
0 to 14
.05
Nitrogen
1
1902
288
1260 to 3220
.01
(mg/X)
2
764
188
350 to 1575
.01
5
1843
378
210 to 2730
.01
Organic
1
0.51
0.18
.06 to 1.37
.05
Matter
2
0.27
0.15
-.39 to 0.65
.2
(%)
5
0.15
0.09
-.13 to 0.52
.2
PH
1
0.73
1.212
.26 to 1.56
NS
2
-0.33
1.326
-.93 to 0.56
NS
5
0.11
0.561
-.21 to 1.12
NS

119
differences were seen between sample pairs for the 1-year old
and the 2-year old sites, but a significant positive
difference was reported for the 5-year old Clearsprings site.
Magnesium values were an average of 48.3 g/kg higher in mound
soils than in non-mound soils. Manganese values were 2.5 g/kg
higher in the mound soils.
Potassium and sodium each had a statistically significant
and positive difference at each of the three sites. For
potassium, the mean difference was 94.5 g/kg for the 1-year
Tiger Bay site, 55.5 g/kg for the 2-year site, and 79.3 g/kg
for the 5-year site. The mean difference for sodium was 28.3
g/kg for 1-year site, 24.8 g/kg for 2-year site and 7.0 g/kg
for 5-year site.
Nitrogen values followed the same pattern as potassium
and sodium with statistically significant (P < .01) positive
differences at all three sites. Mean differences for the
mound and non-mound soils were 1,902, 764, and 1,843 g/kg for
the 1-, 2-, and 5-year sites, respectively. Tiger Bay mound
samples had a range of nitrogen levels from 2,429 to 4,039
g/kg as compared to 539 to 2,709 g/kg for the non-mound soils.
At the 2-year old Fort Green site, the ranges were 2,450 to
3,325 g/kg and 1,995 to 2,870 g/kg for the mound and non-mound
samples, respectively. For the 5-year old Clearsprings site,
the ranges were 3,899 to 6,699 g/kg for the mound soils and
1,869 to 5,089 g/kg for the non-mound soils.

120
The organic matter analysis was less determinate but
indicated some of the same trends. At the 1-year old Tiger
Bay site, the mean difference for soil organic matter was
significantly different (P < 0.5) and positive. Positive
differences were also shown for 2-year old Fort Green site (27
percent) and the 5-year old Clearsprings site (15 percent),
but these differences were only significant at marginal
levels (P < .20)
Physical Soil Analyses
Bulk density. Bulk density measurements (Table 17) on
soils from the one site that was sampled, the 2-year old Fort
Green site, showed a statistically significant difference
between the means for the mound and non-mound samples. The
mean bulk density of the mound samples was 1.19 g/cm3,
compared to 1.74 g/cm3 for the non-mound samples.
Mound volumes can be calculated from circumference and
height measurements, assuming a conical mound shape. Volumes
range from 50 to 2850 cm3. Based on a average bulk density of
1.2 g/cm3, a mound of average volume (approximately 1250 cm3*
has a soil mass of approximately 1,500 g.
Infiltration Tests. Results of the three water
infiltration tests at the Fort Green site (Table 18) showed
the infiltration rate on mound soils to be considerably higher
than on the adjacent non-mound soils. Mound soil infiltration

121
rates were 5, 17, and 120 times higher than rates on the
adjacent non-mound soils for tests 1, 2, and 3, respectively.
Mound soils had infiltration rates of 0.1 to 6.0 cm/min versus
0.02 to 0.05 for the non-mound soils.

122
Table 17. Results of bulk density analysis of mound and
non-mound soils from 2-year old site (n=7).
Standard
Mean
Error
Range
P
Mound
1.19 g/cm3
0.0735
1.00
to
1.43
.05
Non-mound
1.74 g/cm3
0.0473
1.66
to
1.99

Table 18. Results of water infiltration tests on mound and non-mound soils at the
Fort Green reclamation area.
Soil Type
Infiltration Rate
Test
#1
Mound
Non-mound
Non-mound
(grass)
(algal mat)
11 cm/120 minutes
2 cm/120 minutes
1.5 cm/120 minutes
(0.09 cm/min)
(0.017 cm/min)
(0.012 cm/min)
Test
#2
Mound
Non-mound
(grass)
26 cm/60 minutes
1.5 cm/60 minutes
(0.43 cm/min)
(0.025 cm/min)
Test
#3
Mound
Non-mound
(grass)
>120 cm/20 minutes
1 cm/20 minutes
(>6.0 cm/min)
(0.05 cm/min)
123

DISCUSSION
Marsh Development
Seed Bank Formation
The formation of a seed bank appears to be a relatively
rapid process, beginning almost immediately after the land
surface has been exposed. Seed bank samples from all but the
youngest mine sites fall within or just below the range of
seed density and species diversity found in natural wetlands
in Florida, Iowa, and New Jersey.
The species present in the seed bank samples are largely
the wetland ruderal species characteristic of environments
subject to disturbances such as water level fluctuations.
They are the initial colonizing species, the annuals and
short-lived perennials of exposed mudflats, wetland transition
zones, and shallow littoral zones. Notably absent are the
late successional marsh species: the emergent macrophytes,
submergent macrophytes, and free-floating aquatic species.
A possible reason is the germination conditions used in the
seed bank tests, which were similar to those of an exposed
mudflat, but the absence of the seeds of the late successional
species from the samples is a more likely cause. The seeds
124

125
and fruiting bodies of many macrophytes (pickerelweed, water
hyacinth, cow-lily (Nuphar luteum), white water-lily (Nvmphaea
odorata)/ Saaittaria. and Peltandra virginica are large enough
to be easily seen, and no large seeds were observed in any of
the samples.
The question arises of how pickerelweed, Saaittaria. cow-
lily, and white water-lily could be present in at least a few
of the wetlands sampled, if none of their seeds were detected
in this assay. It may be beneficial to discuss the species
present in the seed bank samples versus those conspicuous by
their absence in terms of successional status and life history
characteristics of the adult, established phase and juvenile,
regenerative phase. Regenerative strategies may be related
to successional status.
Formation of a persistent seed bank represents only one
of three regenerative strategies used by wetland plants; the
others are vegetative expansion and production of numerous
wind-dispersed seeds. Generally, vegetative expansion, is
successful where the adult plant is already established. Most
long-lived macrophytes are capable of vegetative expansion
which allows for rapid colonization of open space, such as
small patch disturbances within a large existing stand of
marsh vegetation. In habitats characterized by chronic but
unpredictable disturbance (fire, flood, or drought), where
vegetative structure is destroyed over large areas, the
persistent seed bank is typically the primary regenerative

126
mechanism. The third regenerative strategy employed by
wetland plants, the production of numerous wind-dispersed
seeds, is useful in colonizing near and distant open areas,
especially those that lack a seed bank.
Many species employ more than one strategy. Seeds of
most wind-dispersed species remain viable at least for short
periods of time in a seed bank. Cattail uses all three
regenerative strategies; it is capable of rapid vegetative
growth and produces prodigious amounts of wind-dispersed
seeds, which are also capable of lying dormant in a seed bank.
The perennial macrophytes present within the wetland
zones sampled may rely on vegetative expansion as their
primary regenerative strategy. Alternatively, their seeds may
have been present but in relatively scarce amounts or a
patchy distribution. As noted earlier, all root and rhizome
material was removed from the samples. In hindsight, it would
have been instructive to retain the root/rhizome material and
check for sprouting.
Even for species that use vegetative expansion as the
primary regenerative strategy, the production of viable seed
represents an essential component of the total regenerative
strategy.
Formation and Stability of Macrophyte Communities
In regard to the pattern of succession observed at the
Fort Green marsh, the vegetation dynamics described in this

127
study show that the plant communities that developed in the
two treatment areas differed in species composition and that
these differences remained stable through at least the first
four growing seasons. This stability suggests that initially
established vegetation can occupy the available open space and
resist invasion or encroachment by other taxa. Dense stands
of pickerelweed established in the muck treatment areas
remained stable and were not invaded by cattail, primrose
willow, or other aggressive weedy species typically associated
with arrested succession on unreclaimed phosphate-mined lands.
Similarly, dense stands of cattail have also remained stable,
resisting invasion. In contrast, open stands of cattail in
other portions of the wetland were invaded by bulrush in 1984
and 1985. Recent studies show that dense stands of bulrush
have since developed in these areas, competitively displacing
the cattail (G.R. Best, personal communication, 1988) .
Bulrush showed an ability for widespread dispersal of
waterborne seeds, colonization, and rapid vegetative
expansion.
The marsh transect studies indicated that the initial
floristic composition, sensu Egler, largely determined the
species composition within the marsh, and that in the absence
of disturbance, the initial vegetation pattern and species
composition are maintained for some time, possibly even long
term.

128
Patch dynamics. The use of permanent transects allowed the
fate of individual patches to be tracked through time. The
large stands of cattail and pickerelweed developed from
individual plants or patches that gradually coalesced into
larger units. A similar pattern of plant establishment can
occur on abandoned coal-mined land, as patches or islands that
grew individually and eventually coalesced (Game et al.,
1982) Some patches disappear and are replaced by an
individual or group of individuals of another species. This
suggests that a patch has to be of some critical size before
it can be successfully established, and that the "critical"
patch size probably changes as a function of the surrounding
vegetation and the growth rate of the species.
The vegetation pattern composition and species
composition of a marsh community appear to be largely a
function of the propagules available and the prevailing
environmental conditions which supports the seed
bank/environmental filter model described by van der Valk
(1981). The community responds to an array of environmental
factors that affect its composition. Major environmental
factors affecting wetland communities include depth, duration,
and seasonal pattern of flooding, and fire.
Effect of Herbivorv. Herbivory can also be an important
factor regulating species composition and productivity in
wetlands. Feral hogs are common in the Payne Creek floodplain

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and create patch disturbances of varying size within the
wetland. The affected areas are typically disturbed down to
the subsoil, with all vegetation removed. The hog activity
observed during the marsh study was generally restricted to
the wetland/upland transition zone. Bersok (1986) found the
impact of the foraging hogs in this marsh was limited to
monospecific stands of cattail, and patches opened by hogs
were recolonized by vegetative expansion of the surrounding
cattail plants. This type of disturbance may be similar,
although less extensive, to the muskrat "eatouts" described
by van der Valk and Davis (1976) and Weller (1981) in marshes
in the midwest. The effect is to create a shifting mosaic of
open areas available for colonization.
Effect of Hvdroperiod and Drought. The hydroperiod factors
of depth, duration and seasonal pattern of flooding have a
broader impact than hog activity on the marsh. The water
level fluctuations provide a seasonal dynamic. Of more
importance though are the events with periods longer than a
year, such as the regional drought cycle that occurred from
fall 1984 through summer 1985.
As the drought cycle is a natural part of the climatic
regime, it is one to which a wetland must be adapted. The
reaction to the 1984-85 drought showed that the marsh had
developed a mechanism to respond to environmental change.
Drought conditions exposed previously flooded but unvegetated

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areas that were colonized subsequently and rapidly by a
variety of species. The timing of the drought and the species
composition on the exposed flats demonstrated that the source
of the colonizing species was the seed bank. The wetland had
developed its own seed bank, which is one of the principal
response mechanisms of wetlands to wide fluctuations in water
level.
Mature wetland systems respond to change with an in situ
mechanism that includes the seedbank as a major component.
In a short period, the Fort Green wetland has developed its
own seed bank. The muck applied in 1982 provided an instant
seed bank to certain areas, but the vegetation dynamics
highlighted during the drought occurred in areas where no muck
had been applied. Even on the muck treatment transects (97,
105, and 139) the rise of dogfennel and bulrush was confined
to those portions that had not received the muck treatment.
The establishment of bulrush and Saqittaria on drought-
exposed flats at the north end of the site is particularly
interesting, as the propagule source was undoubtedly from
within the wetland itself, and highlights the autogenic aspect
of community development in seedbank formation. Bulrush and
Saqittaria were planted; initially established plants spread
vegetatively, produced seed, and now act as seed sources for
further colonization. The formation of an internally
generated seed bank may be one indicator of ecosystem
maturity.

131
Monitoring the fate of the drought-stressed or drought-
killed macrophyte communities will provide some additional
insight into community dynamics in future years. Major
patches of cattail and pickerelweed senesced in response to
the drought (Figures 15a through 15f). Only time will
indicate whether the whole plant was killed or only the
aboveground portions. If the latter is the case, then the
drought may have only hastened the annual fall senescence, as
the aboveground portions of both taxa annually die back and
the plants overwinter as leafless rhizomes. Even if large
patches were killed by the drought, species replacement may
be slowed or inhibited by the presence of standing dead plant
tissue; since as these studies have shown, an occupied space
is difficult to colonize.
The marsh transect study does not and cannot address the
long-term stability of created marsh communities like the Fort
Green site. There is no reason to believe that the marsh
system will not eventually develop into a forested wetland.
Tree seedlings planted within the wetland have done quite well
through the first four growing seasons (Best and Erwin, 1984;
Erwin et al., 1985). The mature marsh system may actually be
an immature swamp system.

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Wetland Succession Model
Role of Life History Characteristics
Regenerative strategies and other life history
characteristics are the foundation of van der Valk's wetland
succession model. The plant community's response to climatic
cycles of flood and drought and changing environmental
conditions is analyzed through the life history char
acteristics of the species residing in the seed bank. The
environmental factors in the model act as a "sieve" and
screen species from the seed bank. The life history
characteristics considered in the model include: propagule
longevity (short-lived dispersing or long-lived seed bank
forming), life span of the established plant (annual or
perennial), and propagule establishment requirements
(germination under drawdown or flooded conditions) The model
has generally been applied to succession in marsh systems, but
would seem to be equally appropriate for forested wetlands.
The addition of woody species could be easily accomplished by
incorporating the appropriate life history characteristics for
propagule longevity, propagule establishment requirements, and
life span of the established plant.
Importance of Allogenic and Autogenic Factors
The van der Valk model is useful in describing some
aspects of wetland succession and showing the importance of

133
allogenic forces (the environmental sieve) on the wetland
vegetation. The model emphasizes, as did Gleason and others
(Drury and Nisbet, 1973; White, 1979), that the key to
vegetation dynamics lies in understanding the life history
characteristics of the species constituting the vegetation.
This suggests that succession can be explained entirely as a
disintegrated individualistic phenomenon.
A conceptual model with a focus limited to allogenic
factors and the life history strategies of the individual
species ignores many of the biological properties of the
wetland community. The model's focus on secondary succession
assumes that the community structure is already in place and
does not account for the processes that build that structure.
The model does not explicitly recognize the autogenic
processes and, therefore, lacks the feedback to show how the
environmental sieve can itself be modified to some extent by
the wetland vegetation.
An example of autogenic feedback is the formation of an
organic soil through peat deposition. Wetland succession can
occur on mineral soil, depending on the site conditions and
the nature of the disturbance that initiated the succession.
Certainly, in the case of unreclaimed mined land, the wetland
community will develop on mineral substrate. Through time,
an organic substrate accumulates as litterfall exceeds
decomposition. The accumulated organic sediments raise the
effective ground level in the wetland, thus altering the

134
effects of changes in depth frequency and duration of
flooding. The organic sediments also provide a rooting
medium, seed storage medium, and microfaunal habitat that is
quite different from the underlying mineral substrate.
The model fails to recognize that wetlands tend to change
with time from "young" to "older," more mature stages (Mitch
and Gosseklink, 1986). Young stages after establishment are
characterized by (1) plant species that are opportunistic,
early colonizers capable of being established from seed and
growing in a variety of different habitats, (2) soils that are
typically mineral in nature with low organic matter content,
and (3) subsurface hydrology and chemistry controlled by the
mineral soil. As the system ages, it becomes more "mature":
(1) the plant community may become dominated by species more
characteristic of mature wetland systems, (2) the wetland
soils may gradually change and gain an increasing amount of
organic matter, and (3) the subsurface hydrology and chemistry
may change in response to the changes in wetland soils.
Maturation is to a large extent the action of the
autogenic processes within the wetland. The accumulation of
sediments and the formation of an organic soil is due to
litter production, decomposition, and the depth and duration
of flooding. By building the soil structure, the biological
community provides a feedback to the environmental sieve and
modifies its effects. The mature community has a greater
degree of internal control than the young community.

135
Another example of the process is found with cypress domes
which may influence the shape and depth of their own basins
through the production of acid waters, that percolate down and
cause solution of the underlying limestone (Odum, 1984).
Also, the sawgrass marshes of the Florida Everglades are fire-
adapted communities whose continued survival depends upon fire
(Wade et al., 1980). The sawgrass plants accumulate fuel in
the form of standing-dead leaf litter, and when sufficient
litter has accumulated and conditions are right, a fire may
occur. Fire is an allogenic process, but the timing,
frequency, and severity of the fire are influenced by the
growth characteristics of the sawgrass.
Another excellent example of this kind of feedback loop
is discussed by Weller (1981). In midwestern prairie pothole
marshes, the vegetation is periodically destroyed by muskrats.
New emergent vegetation cannot become established until a dry
year exposes the substrate. A typical succession follows
until cattails out-compete the other plant species. This sets
the stage for another muskrat population explosion. The cycle
has a 6- to 8-year frequency that depends on both the biotic
vegetation-muskrat interaction and the abiotic water level-
climate cycle.
Eclectic Wetland Succession Paradigm
Evidence supports the conclusion that both allogenic and
autogenic forces act to change wetland vegetation. A paradigm

136
or conceptual model of wetland succession must recognize both
these forces and the interplay or feedback between them. An
alternative formulation of the van der Valk model (Figure 16)
can be developed to include other system components, such as
the wetland substrate and consumers, and to show the feedback
relationships between the components and the environmental
sieve.
With regard to the competing paradigms (initial
floristics, inhibition, relay floristics, coevolution, and
self-organization), this work and other studies indicate that
all are operating at some time during wetland succession. The
formation of plant communities from seed/propagule banks
following disturbance is a case of initial floristics. Bersok
(1986) found no significant difference between tree seedling
success in cleared plots versus cattail plots. Pickerelweed
and cattail stands that remain stable in the absence of
disturbance and support to the inhibition model. Coevolution
and relay floristics are important in wetland tree dispersal;
bird and mammal species involved in seed dispersal must have
their habitat requirements satisfied before they will use the
site. Seed/propagule banks and accumulated belowground
structures (e.g., roots, rhizomes) provide a storage of
"choices" for all environmental contingencies, thus
supporting the self-organization model.

Figure 17. Energy circuit diagram of a revised van der Valk's wetland succession model
with feedback pathways added to indicate the influence of autogenic processed in
modifying the effects and action of the environmental sieve (see Figure 2 for
comparison).

Environmental
I Conditions J

139
Upland Forest Plots
Seed Germination and Survival
The germination results and accompanying survival rates
for the seed highlight several points. First, germination
rates between species differ widely under field conditions,
as shown by the two extremes of magnolia with no seeds
germinating and oaks with nearly 100 percent germination.
Germination was low for hickory, sugarberry, sweetgum and
cabbage palm. Factors apparently affecting germination
success include seed quality, site condition, seed predation,
and seed size. The survival of individuals that germinated
exhibited interesting species-specific trends that appear
related to seed size and seedling adaptations.
Effect of Seed Quality. Sugarberry, sweetgum, hickory,
cabbage palm, and magnolia seeds had been collected a year
before the study and stored dry at 4C; oak acorns were
collected the month before planting and stored outside in
potting soil. The storage regime, as well as the initial
quality of the seed, could have had an effect on germination
potential. Many of the acorns were nearly germinating when
planted. Also, because germination was determined only from
the two sampling periods in March and October, any seeds that
germinated but survived only a short time for would have been
overlooked. This factor would have been more critical for

140
sugarberry and sweetgum, since these species produce a rather
delicate seedling.
Effect of site conditions. Seeds respond to
environmental cues to germinate. In some cases, dormancy must
be overcome. It is possible that the conditions in the field
plots were more generally suited for some species than others.
Effect of seed predation. Losses of seed and young
seedlings could also bias the germination results. Seed
losses to birds and small mammals are always a danger to any
direct-seeding operation and are one of the primary causes of
low germination in natural conditions, but for large-seeded
species, this is also a necessary cost of dispersal. Freshly
disturbed soil often attracts animals that consume seeds as
part of their diet. Armadillos were observed on the study
plots and raccoons, field mice, and feral hogs were also
present in the reclamation area.
Two factors were observed to lower the germination
potential of hickory, one physical and the other biological.
The hickory nut is very large and was easily winnowed out of
the soil during heavy rain. This process may have been aided
by the removal of hickory nuts by armadillos. Tracks and
signs of soil disturbance in the plots by these animals were
seen on several occasions, and the signs were usually
associated with the presence of only the outer husks of the
hickory nut.

141
No other seed predators were ever in evidence, although
the freshly disturbed and seeded plots could have attracted
birds and small mammals alike. Seed loss from predation is
a process occurring regularly in natural systems.
Effect of Seed Size. The germination and survival data
(see Tables 9 and 10) highlighted some differences concerning
seed size and seedling growth form. The species used in the
seed plots fall into three categories based on seed size.
Sweetgum has a small winged seed adapted for wind dispersal,
and the small seed contains little food to nourish a young
seedling after germination. Both sugarberry and cabbage palm
have intermediate-sized seeds. The seeds have a fleshy
exocarp to attract birds and mammals as dispersal agents, and
both have modified cotyledons for food storage. Hickory,
laurel oak, and live oak produce large, heavy seeds that
obviously do not disperse far on their own. These species are
highly dependent on animals for that function. Acorns and
hickory nuts have large, starchy cotyledons that provide
nourishment to the developing seedling, as well as to
potential seed predators.
The relationship between the food reserve of modified
cotyledons and the survival rate of a germinated seed is
striking. The large-seeded species had high rates of
survival; 75 percent of all germinating hickories and 87
percent of all oaks survived. In contrast, only 33 percent
of the sweetgum individuals survived the first growing season.

142
In the intermediate seed-size group, sugarberry had low
survival while cabbage palm had the highest possible survival.
The cabbage palm results may be anomalous, both because
of the phenology of this species and the sampling schedule.
During the first sampling period in March, no cabbage palm
seedlings were present on any of the plots. All cabbage palm
seedlings present in the October census had germinated between
late spring and summer. Under this schedule cabbage palm
seedlings had 100 percent survival. This could be misleading,
because the cabbage palm seedling has a single, short, very
leathery leaf, that resists decay for some time, even if dead.
If cabbage palm seeds had germinated and the seedling later
succumbed, the leaf could have remained long enough to be
counted in the survey. Because there is no evidence to
support this possibility, it is assumed that there may have
been some slight mortality, but that survival rates for
cabbage palm were high.
The relatively superior performance of large-seeded
species in direct-seeding trials has been noted in other
studies. Tourney and Korstian (1942) noted that seeds
containing a large amount of reserve food and germinating in
early spring are better adapted for direct seeding than small
seeds that are slow to germinate and produce plants of slow
juvenile growth. Tackett and Grimes (1983) seeded three
large-seeded species (Ouercus rubra, Q. palustris. and Q.
macrocarpa) with two small-seeded species (Paulownia tomentosa

143
and Alnus glutinosa) and found that after 5 years, a greater
number of oak seedlings were established than seedlings of
the small-seeded species.
Seedling Adaptations to Drought Stress. Seedling growth
form can be especially important in determining the fate of
germinating seeds. Along with its tough, leathery leaf, the
cabbage palm seedling possesses a thick, leathery root system
and is well adapted to handling drought stress. The
aboveground and belowground tissues are strong enough not to
collapse under moisture tension. Conversely,the sugarberry
seedling has a delicate stem and root that are more rapidly
affected by moisture stress. It is thus reasonable to assume
that sugarberry mortality would be higher than that of cabbage
palm if dessication were a problem, as is the case on exposed,
unvegetated, overburden soils.
This analysis of seedling anatomy can be extended to the
other taxa in the study. Sweetgum, like sugarberry, produces
a seedling with delicate shoot and root and would be expected
to be killed more easily by drought stress. Hickory and oak
both produce a stout woody shoot and a tough fibrous root
system that makes them better adapted for coping with water
stress.
The survival data for all species summed together showed
that the enhanced colonizer treatment had the lowest values.
Several factors may have influenced this outcome. Competition

144
among tree seedlings and herbaceous plants may have been more
intense in the enhanced treatment plots, thus reducing
survival and possibly germination. Allelopathic inhibition of
either growth or germination of woody plants by the species
added is also possible. One of the enhanced colonizers,
Andropogon virainicus. has been reputed to produce allelo-
chemicals that inhibit the growth of other plant species
(Rice, 1978).
Effect of Erosion. When the major erosion problems began
in early January 1984, the extent and degree of erosion on
site were assessed and mapped. An examination of the map and
field notes from this time show that eight seed plots were
affected by erosion rills. By chance, the affected plots were
evenly distributed among the four treatments. Several plots
affected by erosion exhibited low survival and others showed
high values. Only in two cases were seeds observed to have
been washed out of plots (numbers 12 and 13) and these were
replaced by hand. However, this does not preclude the
possibility of some seeds having been lost completely from
some plots or washed from one plot into a down-slope plot.
One indication that there was no significant movement of seed
between plots is that no individuals of any of the planted
legume species were ever found in plots other than the ones
in which they were placed.
The germination and survival results for the individual
species were varied and less clear in support of one of the

145
three models. Hickory and sweetgum exhibited no significant
differences in survival under any of the four treatments,
which provides support for the initial floristics model. The
results may be influenced by the generally very low survival
values, as some plots had only a single individual or none at
all.
Germination and survival results for sugarberry do not
clearly favor any of the three models, and also may have been
affected by generally low numbers of seeds germinating and
surviving (less than 6 percent overall).
Cabbage palm germination results appear to reject the
relay floristics model but do not clearly favor either initial
floristics or inhibition. The weeded mean was higher than the
means for the two enhanced colonizer treatments (legumes and
old-field weeds) but the mean was not different from the
colonized treatment where the treatment seeds were added
naturally.
The results for oak also do not clearly support any of
the three models, although there is some support for rejecting
the relay floristics model. The weeded, natural colonizer,
and enhanced legume means were significantly different from
and higher than the enhanced colonizer mean, but the three
means were not different from each other. Once again, the
enhanced treatment came out lowest, raising the question of
whether competition, allelopathy, or another form of
inhibition was involved because of the species added in this

146
treatment. The means for the other three treatments were not
significantly different. The oak results may be similar to
those of hickory, suggesting a causal relationship between
large food reserves in the seed and less treatment-related
mortality in the first growing season.
Height Growth
Seed plots. When seedling height data are summed for all
species, significantly different and greater height growth
appear to be a result of the weeding treatment. This result
seems clearcut and profound, as seedlings in the multi-species
plots grew significantly better under the weeding treatment,
and relay floristics and initial floristics models must
therefore be rejected in favor of the inhibition model.
Closer examination, however, indicates the results may
actually support more than one model.
When the growth data are summed over all species, the
resultant data set is heavily biased toward the oak; both
because the two oak species were combined to avoid skewing
results from misidentification of individual seedlings and
because oak had a higher level of germination and survival
than the other taxa. Oak seedlings made up 74 percent of all
seedlings found, whereas cabbage palm comprised 12 percent,
hickory 7 percent, and sugarberry and sweetgum 5 and 2
percent, respectively. It is therefore not surprising that
the height growth analysis for oak has exactly the same

147
results as the analysis for all species summed. The vastly
greater number of oak seedlings masks the responses of the
other species, which, if examined separately or at least apart
from the oak data, lead to a much different conclusion.
The results of the height growth analysis for the other
four species are surprisingly uniform and contradictory to the
oak results. The ANOVAs for each show no significant
differences in mean seedling height among any of the four
treatment means, which supports rejection of the relay
floristics and inhibition models in favor of the initial
floristics model. This may indicate that individual species
do not show the same response.
In addition, the erosion problems encountered early in
the study provide support for the relay floristics model, by
showing that the early colonizing plants help stabilize soil.
Transplant plots. The transplant plot seedling growth
data can be considered to provide either clarity or more
confusion. Unlike the seed plot data, the transplant plots
did not have differing interpretations depending on whether
species were combined or treated separately. The result were
the same for three cases and barely dissimilar for the fourth
case. For sweetgum, oak, and all species combined only the
weeded treatment was shown to be significantly different and
it had the highest height growth. For cabbage palm, the mean
seedling growth in the weeded treatment was not clearly

148
superior but it was, along with the natural colonizer
treatment, significantly different from and higher than the
enhanced legume treatment mean.
Comparisons between seed and transplant plots. The
seedling height growth results from the seed and seedling
plots provide two views of the interaction between later-
arriving tree species and colonizing plants. Because the three
species used in the seedling transplant plots were also in the
seed plots, a valuable means of comparison was provided.
The oak seedlings exhibited the same height growth
response under experimental treatments in both the direct-
seeded and transplant plots. The increased height growth
under weeded conditions was common to both, as well as for
all species combined. These two cases provide some support
for the inhibition model, the oak bias in the seed plots must
be considered when all species are combined.
Sweetgum demonstrated an interesting contradiction in
response to treatments from the seed and transplant
experiments. Growth data from the seed plots favored the
initial floristics model, as none of the treatment means were
significantly different. In the transplant plots, however,
sweetgum growth was best in the weeded treatment, thus
favoring the inhibition model. The results indicate another
variable to consider; that is, that species may have different
life history stages that respond differently to early
colonizing species. If this is true, then the question of

149
addressing the pattern and process of ecosystem development
becomes inextricably more complicated. However, the very low
levels of germination/survival of sweetgum in the seed plots
caution against giving strong support to the results.
Like sweetgum, cabbage palm also showed an opposite
response to treatment effects from the seed and transplant
plots. The seed plot data favored the acceptance of the
initial floristics model, while the transplant plot results
were not clearly weighed toward either the inhibition or relay
floristics models.
The two experiments can be seen to address the same
fundamental issues of earliest succession at two succeeding
stages of development. The direct-seeded plots simulated the
critical period during the first growing season after
propagules arrive at an open, uncolonized landscape. The
proper cues must be made for germination, establishment
depends on a suitable microenvironment, and adequate resources
must be continually available for survival. The transplant
plots mimicked the second growing season, the next stage in
woody plant life, which is less precarious than germination
and establishment but still heavily dependent on the quality
of the microenvironment. The results of the experiments are
strikingly similar for these two stages; in no case was
germination or growth (as measured by height change) enhanced
or increased by the presence of the natural or enhanced
colonizer treatments. The results appear to offer strong

150
support for questioning the validity of the initial floristics
and especially the relay floristics paradigms.
It is somewhat surprising that the height growth results
most strongly reject the relay floristics paradigm, as it was
assumed at the outset to be important during the early stages
of primary succession on phosphate-mined lands. Unvegetated
overburden soils provide seeds and seedlings little
amelioration or insulation from extreme physical conditions
such as intense light, extremes of temperature, dessication,
and erosion, that are sources of stress or mortality. The
value of colonizing herbs in soil stabilization was
demonstrated in the early part of the field tests, but the
effect is not apparent in the results.
Species Removal
Several previous studies have examined the effects of
species removal on the course of old-field succession. As
with the seed and transplant plots of this study, research
tends to support the view that succession cannot be succinctly
explained by single-concept models. In a field experiment
designed to test whether annual plants were needed to "prepare
the way" for perennial plants, McCormick (1968) removed annual
plants from a portion of a first-year-old field in
Pennsylvania but allowed them to grow elsewhere. The
subsequent biomass of individual perennial plants on the
annual-free areas was many (15 to 82) times greater than on

151
areas with annuals. Using the decision criteria of Connell
and Slatyer (1977), this experiment supports the inhibition
model.
Pinder (1974) studied the effects of the presence of the
dominant grasses on the productivity of subordinate forbs
within a perennial-grass, old-field community. He found that
removing the dominants increased the net productivity of
almost all subordinate species.
Hils and Vankat (1983) used the species-removal approach
to test Connell and Slatyer's (1977) models in the first year
of old-field succession. Their experimental treatments
included removal of annuals, annuals and biennials, and
perennials. Results from the first growing season favored
acceptance of the initial floristics model, but the authors
cautioned that more than one model of succession may apply in
the same field at the same time, reflecting the spatial
heterogeneity of the old-field community. The same old-field
plots were further studied by Zimmerman and Vankat (1984).
The species-removal treatments were maintained in the second
year and the developing community was studied for the next
three years. The initial floristics model was still supported
at the end of 5 years because the authors found no
statistically significant differences between the biomass of
perennials grown with annuals and biennials and the biomass
of those grown alone. Succession resulted in the development
of nearly identical communities in the two treatments. The

152
two studies imply that the colonizing herbs had little effect
on perennial herb species.
None of the four studies found any support for the relay
floristics model, but all dealt with only herbaceous plants
in an old-field succession sequence. As noted earlier, relay
floristics may be most appropriate for describing primary
succession and the establishment and growth of late
successional woody plants.
The relay floristics model predicts that later
successional woody species only enter the developmental cycle
after harsh conditions have been ameliorated by the colonizing
vegetation. The pioneer plant community is commonly assumed
to play a role in the accumulation of soil organic matter,
development of soil profiles, building of vegetation structure
to provide shade and reduction of erosion from raindrops,
buildup of soil nutrient levels, development of recycling from
consumers, and development of symbiotic relations
(plant/mycorrhizae, for example). Evidence in support of the
relay floristics model comes from studies of primary
succession on newly exposed surfaces. Crocker and Major (1955)
and Lawrence et al. (1967) have suggested that the
characteristics of soils newly exposed by a retreating Alaskan
glacier make the establishment of plants extremely difficult.
Pioneer species that are able to colonize will ameliorate
these conditions, reducing pH, increasing nitrogen, adding a
layer of organic matter over the hardpan, and reducing

153
dessicating winds. Seedlings of spruce trees appear under the
new conditions, but seldom, if ever, on the original exposed
sites. Another example is the primary succession on sand
dunes on lake shores (Cowles, 1899; Olson, 1958). Pioneer
plants stabilize the moving sand, which otherwise would be
unsuitable for colonization by later-appearing species.
Competition
Three experimental treatments (enhanced legume, natural
colonizers, and enhanced colonizers) provided three levels of
examining the issue of relay floristics versus competition.
The natural colonizer treatment looks at relay floristics in
the classical sense. The enhanced colonizer treatment tests
the hypothesis that "more is better" for the establishment of
climax species. The enhanced legume treatment tests the role
of nitrogen-fixing species as colonizers. Tall, fast-growing
legumes like Sesbania macrocarpa. S. punicea. and S. vesicaria
could provide shade for young seedlings, attract pollinators,
and provide perches for birds and cover for small mammals.
It was assumed all these benefits could accelerate the rate
of ecosystem development.
With the exception of soil stabilization, none of these
presumed benefits was as influential as the reduction in
competition for resources during the first year of vegetation
development at this particular site. It may be that scarce
resources, such as moisture or soil nitrogen, limit vegetation

154
development and that the relatively slower-growing woody
species show less vigorous growth when faced with herbaceous
competitors. Because forest development is a long-term
process (on the order of 50 to several hundred years), the
experimental plots provide a very controlled view of only the
earliest stages. It is possible that the presumed benefits
of the early colonizers take time to accrue and have an
effect. The effect of litter may be an example.
Foresters have long noted competition as a factor
influencing successful reforestation. Tourney and Korstian
(1931) note that a low, dense cover of grasses and herbs is
a decided disadvantage to reforestation; not only does it pro
vide a retreat for rodents and other seed-eating animals but,
as soon as germination occurs, it directly competes with the
young seedlings. The roots of the herbaceous competitors draw
nutrients and water from the surface layers of the soil, and
the intensity of competition often proves fatal to the trees.
Competition has also been documented as a cause of
decreased establishment and growth of tree seedlings in
reclamation. Tackett and Graves (1983) cited competition by
an herbaceous cover crop as a significant factor in reducing
the height growth of tree seedlings. Vogel and Berg (1973)
also found competition from herbaceous plants could be
detrimental to growth of tree seedlings. Brown (1973) cited
competition from herbaceous plants as one of the factors
affecting germination and initial survival of seedlings.

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Succession
The preceding discussion of the field test results
effectively illustrates the uncertainties and contradictions
impeding interpretation of ecosystem development. The three
paradigms of succession (relay floristics, initial floristics,
and inhibition) are too rigidly and narrowly constructed. The
field tests used in this study, which followed the
experimental design of Connell and Slatyer (1979), assume that
the paradigms are mutually exclusive and that the pattern and
course of succession is determined by only one. It is more
likely that all three operate at some level during the course
of succession. Hils and Vankat (1982) reached the same
conclusion, finding that more than one model of succession may
apply in one old-field at the same time reflecting the spatial
heterogeneity of the old-field community.
Connell and Slatyer's (1977) approach appears to address
only secondary succession. By omitting primary succession
only implicitly, they further cloud the issue. As noted
above, temporal factors need to be considered, and it is also
likely that different paradigms may be appropriate at
different stages of development.
Role of fauna in succession. The Connell and Slatyer
(1977) approach is also deficient in not considering the role
of micro- and macrofauna in ecosystem development. Animals
serve such functions in the community as seed dispersal, and

156
pollination. This study addresses the effect of mound
building ants in ecosystem development on mined lands; the
role of earthworms in soil turnover and nutrient cycling
provides another well-documented example of the influence of
animals on vegetation development.
Seed dispersal by animals, especially birds, is a
potentially very important means for trees to invade disturbed
areas. If the developing community provides the proper
habitat requirements for seed-dispersing agents, then the
invasion by later successional species may proceed much
faster. Evidence of tree seed dispersal by birds can be seen
in the woody flora found along almost any fence row, where
seedlings of berry-producing species like black cherry (Prunus
sertina), hercules-club (Zanthoxvlum clava-heuculis), and
sugarberry are quite common. In many of the central Florida
citrus groves abandoned after the severe winter freeze of
1983, laurel oak and black cherry seedlings invaded within the
first year or two, typically found beneath the standing-dead
citrus trees. This invasion pattern was a result of the perch
sites provided by the dead citrus trees and used by the seed
dispersing birds. Field studies by McClanahan (1984) and
Wolf (1986) indicate that seed dispersal to a large degree
determines the rate at which forested ecosystems recover from
catastrophic disturbances such as strip-mining. For animal-
dispersed seeds, site attractiveness appeared to be more
important than distance.

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Development of critical structure during primary
succession. In primary succession on highly disturbed
landscapes, the dispersal, arrival, and successful
establishment of many late successional tree species may
require some degree of "site preparation." The site
attractiveness provides an excellent example of how seed
dispersal is constrained until the site is suitable for the
dispersal agent. Colonizing annuals, biennials, and
herbaceous perennials do not offer attractive perch sites for
many seed-dispersing birds.
Many tree species have obligate or facultative symbiotic
relationships with soil fungi, called mycorrhizae. The
successful establishment and growth of some late
successional tree species may be tied to presence of the
appropriate fungal symbiont (Wallace, 1988) The aboveground
succession may be linked to a belowground succession.
Caveats
Finally, some degree of caution is needed in interpreting
the first-year results from the Gardinier seed and seedling
plots. Some of the most obvious considerations are as
follows:
1. Results are from a single growing season but conclusions
are extrapolated to the long-term process of ecosystem
development.
2. Experimental treatments were fixed, not random;
therefore, statistical inferences are appropriate only

158
to the treatment levels selected and not to a population
of possible levels.
3. A limited number of tree species was used in the tests,
and although the responses of the species differ, results
are interpreted in terms of a whole forest.
4. Results are from a single set of tests carried out on one
soil type at one site, so conclusions about the process
of forest development must be couched in appropriate
scope and scale.
6. Allelopathic effects of herbaceous species on each other
and on woody plants may be important and were not
investigated.
7. The weeding treatment may provide indirect benefits by
disturbing the soil, increasing the rate of water
infiltration by breaking up soil crusts commonly found
on exposed overburden soils.
8. In the seeded plots it was easier to locate and measure
seedlings in the seed plots receiving the weeding
treatment. It is possible that some small seedlings were
overlooked in the other treatment plots. So, then
germination results would be biased in favor of the
weeded treatment.
Mound-Building Ants
Mound Survey
The mound densities measured in the survey ranged from
560/ha to 2,100/ha on 1 to 5-year old sites. Kangas (1983)
found ant mound density increased dramatically over the first
10 years on unreclaimed phosphate-mined land, from 2,000/ha
at 1 year to over 8,000/ha at a 10-year old site.
Adams et al. (1978) estimated fire ant mound density in
agricultural fields in Brunswick County, North Carolina, at
141 mature mounds per hectare. Baroni-Urbani and Kannowski

159
(1974) estimated the fire ant mound density of a Louisiana
pasture at 96/ha. The relatively lower mound densities in
these two studies may be a result of site-specific factors,
but are more likely due to the authors* focus on large mature
mounds.
Kangas (1983) also noted a general increase in size of
ant nests with increasing site age up to a point and then a
later decline. For example, few ants were seen on a 50-year-
old site. This observation may indicate a change or
succession in the ant fauna through time as the vegetation,
light levels, food quality, and physical and chemical
character of the soil profile change.
Ant Mound Roles
Soil development. Mound building affects soil bulk
density, particle size distribution, and the amount and
distribution of pore space. The bulk density of soils from
the 2-year old site showed mound values to be approximately
80 percent of the non-mound values, 1.19 g/cm3 versus 1.74
g/cm3. Wali and Kannowski (1975) measured the bulk density on
mounds of seven species of ants on prairies in northeastern
North Dakota and found the values to lie in a narrow range of
0.64 to 0.75 g/cm3 in comparison to 1.15 g/cm3 for non-mound
prairie soil. Levan and Stone (1983) measured the bulk
density of a black meadow ant (Formica fusca) mound as 0.51
g/cm3.

160
A reduction in bulk density may make the soil a better
rooting medium for established plants and possibly for
germinating seeds, as soil aggregates will be broken down.
Probably more important than absolute density differences is
the effect of breaking the surface crust. This may be
especially true on overburden soils, which tend to form very
hard surface crusts, because of a higher clay content than
native soils. Density changes are primarily a result of the
movement of individual soil particles or grains, which
increases pore space. Increased pore space can facilitate
gas exchange, evaporation, and water infiltration.
Mound building breaks up the crust aggregate, thereby
increasing the pore space in the surface horizon. Concomitant
with the surface effects of mound building is the creation of
an elaborate subsurface system of chambers and tunnels.
Tunnel systems extend as much as a meter or more below the
mound and lateral channels may extend outward from the mound
typically for a distance of several meters. The extensive
tunnel system creates an anastomosing network of
interconnected soil macropores that is maintained for the life
of the mound. Some of the soil profile alterations resulting
from ant activities may be lost temporarily during intense
rainfall, but the mound and tunnel system are guickly repaired
by the colony.
Nest construction may cause more rapid alteration of the
soil profile than would biogeochemical processes without

161
animals. Although mound construction is localized, a larger
area affected is altered rapidly and extensively. Channelling
below the mound produces an extensive interconnected network
that penetrates the parent material. Deep channeling and
vertical transport of soil material lead to an alteration of
the soil.
Some of the changes may persist for some time after mound
abandonment. The channel system gradually collapses and the
mound slumps, but soil alterations and nutrient availability
may selectively favor certain plant species long after the
mound has been abandoned. Levan and Stone (1983) estimate
that pedoturbation by ants can be quite significant when
viewed over the long term. Assuming an average mound density
of 2,000/ha and an average mound basal area of 25 cm mounds
occupy approximately 5 percent of the landscape. If it can
be further assumed that the average life of a mound is
approximately 2 years (Lofgren et al., 1975), then all the
soil in a given area may be affected in 40 years time.
Infiltration. An increase in infiltration rates
beneficially alters the water balance of a developing
community by preventing the loss of that scarce commodity,
water. Water infiltration rates were higher in mound soils
than non-mound soils in all measurements. The most obvious
differences in the soil types were the pore space, texture,
and bulk density.

162
Crusts commonly develop on the surface of overburden
soils as they are alternately exposed to wetting and drying.
The crust reduces infiltration and increases runoff relative
to those areas where the crust has been broken. Crusting
causes rainfall to pond on the soil surface, and blue-green
algal mats commonly form on the most frequently ponded areas.
Algal mats provide an additional barrier to water
infiltration.
Ehlers (1975) found that earthworm burrows reaching the
surface improve water drainage. Ursic and Esher (1988)
demonstrated that small mammal burrowing significantly
increased water detention-retention in a pine-covered
catchment and concluded that the numerous interconnected
surface and subsurface burrows created a system that could
accept and retain rain water until it was transmitted to
deeper layers or moved into the soil matrix. In simulated
rain study plots with short-tailed shrews (Blarina
carolinensis) and pine voles (Pitvmvs pinetorum), they showed
that burrowing activities decreased surface runoff by
approximately 25 percent.
Ant tunnels are soil macropores. Dixon (1971) concluded
that large pores can have a profound effect on the
infiltration of water into soils. In a model developed to
study pore size in relation to infiltration, Edwards et al.
(1979) demonstrated that surface-connected holes can

163
effectively transmit water when more water is applied than
can infiltrate.
Nutrient cycling. Results of the chemical analyses
support the hypothesis that foraging activity by ants elevates
levels of some nutrients in the mound relative to adjacent
non-mound areas. Confirmation of the nutrient concentration
role of mound-building ants is one of the central points of
a general model of the role of ants in ecosystem development
(see Figures 4 and 5).
Fire ants have been extensively documented because of
their status as nuisance pests. It is well established that
fire ants are general landscape foragers with a diet
consisting largely of protein from invertebrate prey
supplemented with oils and fats from some plant parts (Lofgren
et al., 1975). Foodstuffs are returned to the mound for
consumption by the colony. The conceptual model predicts that
because the ultimate fate of food materials is ant biomass and
waste products, the mound should have relatively higher levels
of organic matter and inorganic nutrients derived from
microbial breakdown of organic matter in the mound. Soil
chemical analyses showed enhanced nutrient pools in mounds
and, therefore, support that pathway in the conceptual model.
Generally higher levels of exchangeable cations,
particularly potassium, have been reported from ant mounds by
Czerwinski et al. (1969, 1971), Gentry and Stiritz (1972),

164
Rogers and Levigne (1974), and Wali and Kannowski (1975). The
statistically significant, higher levels of potassium mound
soils are evidence of nutrient concentration by animals.
Potassium may also come indirectly from phloem exudates via
aphids (Levan and Stone, 1983), on which fire ants are known
to feed (Lofgren et al., 1975).
Elevated sodium levels in mound soils are more
perplexing. Sodium is a minor essential nutrient for animals
but not for plants. It is also a readily solubilized ion from
a variety of inorganic salts. It is possible that elevated
levels of potassium and sodium may be the result of
differences in evaporation rates between mound and non-mound
soils. The lower bulk density and greater pore space of mound
soils may facilitate evaporation of soil water, resulting in
salt deposition. It is also possible that elevated levels of
potassium and sodium in mound soils are caused by microbial
decomposition of the organic matter in the mounds. The
evaporation hypothesis remains one possible explanation of the
elevated cation levels, but elevated organic matter and
nitrogen levels provide additional support for the biological
concentration argument.
Lack of statistically significant differences for calcium
and magnesium is not surprising, as overburden soils
containing limestone and dolomite typically have high
concentrations of these cations. Concentrations of calcium
and magnesium ranged from several hundred to several thousand

165
grams per kilogram in overburden soils (Wallace, 1988). The
heterogenous nature of overburden soils led to considerable
variation among samples.
No clear differences in pH were observed between the two
soil groups. Wali and Kannowski (1975) found ant activity
increased pH in predominantly acid soils and decreased pH in
predominantly alkaline soils. It is likely that there has
not been sufficient time for ant activities to have an effect
on the young overburden soils at the three sites studied.
Also, the heterogeneous nature of these soils may contribute
to a large statistical variance. It is expected that a pH
reduction attributable to activities of the colony will become
apparent through time.
Plant growth enhancement. The results of the two
plant growth experiments demonstrate that elevated nutrient
levels in mound soil can translate into enhanced plant growth.
The higher cations and nitrogen in mound soil enhanced growth
for both a grass (Paspalum urvillei) and woody plant
(Liquidambar stvraciflua). This supports the field
observation that herbaceous plants, especially grasses,
growing on mounds were more robust than those on adjacent non
mound soils. Indirect evidence is also provided to support
the existence of non-trophic feedbacks as shown in the
feedback loop between plants and ants (see Figures 4 and 5).

166
Ant Model
The importance of mound-building ants in a developing
ecosystem appears to lie in the capture and cycling of
potentially scarce resources, such as nutrients and water.
Growth and development can be stimulated in two ways: (1) by
additions or supplements of energy or resources and (2) by
concentrating and recycling existing resources at a faster
rate. It is the latter method that ants appear to facilitate.
The results of the storages and pathways investigated
support the ideas used to develop the conceptual ant model
(see Figures 4 and 5) Mounds were found to have elevated
nutrient levels that, in turn, produced enhanced plant growth
in greenhouse studies. Taken together, these results support
the existence of a positive feedback loop between ants and
primary producers. The existence of the other proposed
feedback, the effect of ant-mediated pedoturbation on primary
producers, appears to be supported by the infiltration tests.
Indirect evidence of microbial pathways was found
accumulations of organic matter and nutrients. Czerwinski et
al. (1971) showed that enhanced organic matter levels in ant
mounds increased activity of bacterial and fungal
decomposers.
Physical soil alterations resulting from mound building
were not directly linked to enhanced plant growth, but
indirect evidence comes from the beneficial effects of

167
biologically mediated soil turnover on plant growth (Gentry
and Stiritz, 1972; Platt, 1975).
The effects of ants in a developing post-mining landscape
will not be limited to the role of fire ants, as other soil
fauna with both similar and different life histories are also
present on these sites. In addition, the composition of the
soil faunal community will likely change through time.
Fire ants are an exotic species but do not appear to
serve an exotic function. While they are able to displace
other native species of ants, in their absence the native
species can occupy these sites and serve the same function.
Some other ant species may influence the developing ecosystem
in similar ways at different stages.
It is expected that as the post-mining landscape matures,
ants may decline in dominance while earthworms gradually
become more important components of the soil microfauna. Ants
and earthworms may perform much the same function at different
stages of succession. The two intensify different stages of
decomposition; ants mainly with the first stages of
mineralization and earthworms with humification. Petal (1978)
has argued that the contribution of these two groups of
animals to processes within the ecosystem and the range of
their influence are functionally equivalent in environments
with different fertility, plant productivity, rate of
decomposition, and trophic complexity. In infertile soils
with low organic matter and decomposition rates, like young

168
overburden soils, ants speed the return to the soil of
nutrients accumulated in the bodies of other animals. The
role of earthworms appears to be greater in fertile soils,
characteristic of more mature ecosystems, where they speed the
release of nutrients from the organic matter as it is being
decomposed.
Eclectic Synthesis of Paradigms and Implications for
Reclamation Design
Evidence reported in this dissertation supports the
conclusion that both allogenic and autogenic forces act to
change vegetation during primary succession on reclaimed
upland and wetland sites. An encompassing paradigm of
ecological succession must recognize the action of both forces
and the interplay or feedback between them. With regard to
the competing paradigms (initial floristics, inhibition, relay
floristics, coevolution, and self-organization), studies
reported here indicate that all are operating either
simultaneously or at some time during succession on mined
lands. It is likely that different paradigms may be
appropriate at different stages of ecosystem development.
There is no doubt that ecosystems can be studied either
by examining one mechanism at a time or with a holistic,
synthetic ecosystem approach and that valuable information is
contributed by both approaches. It is premature to assert
that a synthesis is not possible (Peet and Christianson,

169
1980) but it is clear that the synthesis is far from
complete. The continuing contradictions about succession
after many decades of study suggest that ecology and the
succession concept may be in the midst of a change in
paradigm. The single concept paradigms of succession
(inhibition, initial floristics, relay floristics in
particular) appear to be flawed and a new paradigm will likely
emerge from a more eclectic synthesis that incorporates and
unifies the concepts of several paradigms. It is clear that
an explanation of the cause and mechanism of succession, and
development of a reasonable consensus on a paradigm of
succession, will require a careful analysis of the historical
background, biases and premises, and philosophy of the idea
and its practitioners, critics, and proponents.
Until such time that a unifying paradigm of succession
is constructed and widely accepted, it is also clear that the
five competing paradigms examined in this dissertation can
provide a theory-based guide for the reclamation of disturbed
land. Reclamation should be viewed as type of engineering
design based on ecological principles. The five paradigms
reviewed in this dissertation can be used as ecological
principles for guiding reclamation design. Using the
paradigms to guide our reclamation design efforts should help
us create functional, self-maintaining ecosystems that
integrate with the surrounding landscape. A clear
understanding of succession also provides an opportunity for

170
forming rational and cost-effective land reclamation
techniques and policies that will enhance and direct the
successional process on mined lands.
Using the five individual paradigms as design principles,
some of the implications of each for the reclamation of strip
mined land are discussed in the following section.
Inhibition
There are many documented examples of inhibited or
arrested succession on mined lands. These studies generally
describe an arrested succession in which the initial species
composition of primary invading species is perpetuated. The
Fort Green marsh study indicated that in the absence of
disturbance, the initial vegetation pattern and species
composition are maintained for some time, possibly even long
term.
Initially established vegetation may be able to resist
invasion by other species through maximum performance for
existing environmental conditions. Under appropriate
conditions, even slow-dispersing, late successional species
are able to become established and occupy the available space.
Once the available space is filled, opportunity for invasion,
even by aggressive species capable of inhibiting succession,
is limited. Consequently, it is feasible to establish
self-maintaining, stable, wetland and upland communities

171
dominated by late successional species able to resist invasion
by aggressive colonizers.
The arrested, or inhibited, succession observed on mined
lands may be largely attributable to restrictions on
dispersal. It is apparent from the field studies reported
here that late successional plant species can become
established, grow, and survive under early successional
conditions. The successional process on disturbed lands can
be influenced and enhanced by facilitating the dispersal and
establishment of the more slowly arriving, later successional
components.
For reclamation, the emphasis should be on: (1)
predicting the soil type and soil moisture conditions
(hydroperiod in wetlands) of the reclaimed system and using
these as guides for determining the type of vegetation that
could be supported; (2) controlling aggressive species capable
of inhibiting succession; and (3) overcoming the dispersal
limitation of many late successional species to get these
species established at the start. On wetland sites, the
application of peat or muck from donor marshes has been
successful in these areas but may not always be feasible
because of the quality of donor material or budgetary
constraints in transporting the material. In such situations,
planting an array of long-lived perennials in patches can
accomplish these goals. At Fort Green large stands of
cattail, pickerelweed, and bulrush developed from individual

172
plants or patches that gradually coalesced into larger units.
A patch has to be of some critical size before it can be
successfully established, and that the "critical" patch size
probably changes as a function of the surrounding vegetation,
the amount of open space available, and the growth rate of the
species. On upland sites, woody species characteristic of
later successional stages can be easily planted or seeded
during early revegetation efforts.
In some cases an arrested successional stage may be
desireable, such as along utility line rights-of-way. If so,
then revegetation efforts can be targeted at enhancing the
establishment of those species capable of arresting succession
on disturbed lands. The use of grazing, mowing, and periodic
burning can also be helpful tools for arresting succession.
For instance, fire may be needed for preventing the
encroachment of woody species into marsh systems.
Initial Floristics
Egler's initial floristic hypothesis portrays old-field
succession as a seed bank response to a change in
environmental conditions. Studies in this dissertation show
that initial floristics is also an important factor during
primary succession on upland and wetland sites. The initial
floristic composition is an important determinant of the type
of vegetation that develops following disturbance. The
vegetation pattern, and species composition of the marsh

173
community at Fort Green was found to be a function of the
interplay between the propagules available and the prevailing
environmental conditions.
The formation of a seed bank in created wetlands appears
to be a relatively rapid process, beginning almost immediately
after the land surface has been exposed, but the species
present in the seed bank samples were predominantly the
initial colonizing species. Notably absent were seeds of the
late successional species: woody taxa, emergent macrophytes,
submergent macrophytes, and free-floating aquatic species.
The implication of the initial floristics paradigm for
reclamation design is that within certain constraints the
species composition of reclaimed upland and wetland
communities can be influenced, an in particular late
successional species can often be established from the start.
For wetland systems, design should focus on the seed/propagule
bank as a critical component of self-maintaining systems. The
use of peat or muck from donor wetlands can provide an instant
seed bank that contains seeds/propagules of early and late
successional species. As shown by the success of the bulrush
plantings at Fort Green, some perennial macrophytes can be
easily established by planting. A diverse array of woody
species can be successfully established by seedling plantings
in both wetland and upland situations.

174
Relay Floristics
In a few cases relay floristics has been demonstrated.
The results from the Gardinier tree plots showed that during
primary succession areas subject to erosion and/or unstable
substrates require a cover crop or nurse crop of early
successional species in order to stabilize the substrate
before later successional species can become established. In
most areas, natural colonization by rapidly dispersing species
will typically provide a cover crop within the first growing
season. In areas subject to erosion, reclamation efforts
should enhance and accelerate establishment of a cover crop.
Seeding is one commonly used method. Spreading of
topsoil/muck from donor upland/wetland sites is another
method.
Coevolution
Within the constraints of resource supply or other
environmental factors the autogenic, biological system is
characterized by strong positive feedbacks among its
components. Classic mutualisms exist between plants and
mycorrhizal fungi, pollinators, and seed dispersers to name
a few examples, but there are also the extended mutualisms
that exist between plants and their rhizosphere, as well as
the interactions that may not fit the standard definition of
mutualism at all, but nonetheless are characterized by strong

175
mutualism at all, but nonetheless are characterized by strong
positive feedback among the system components. The fire ant
model may be an example of this latter type of positive
feedback relationship. Severe disturbances, such as strip
mining sever these links; re-establishing these links should
be an important part of land reclamation.
As discussed earlier, the maturation process within a
developing community largely results from autogenic processes.
One implication of this for reclamation design is that mature
ecosystems have accumulated structure, and in many cases some
of this critical structure can be added during reclamation.
The application of muck from a donor wetland provides not only
a propagule bank of seeds and rhizomes but structure in the
form of the organic material itself and its attendant
microbial and microfaunal component. As noted in the studies
reported in this dissertation, other kinds of autogenically
produced structures can be critical to development of
communities in a primary succession. Some of these critical
structures can also be added to the reclaimed system.
Specific plantings to augment food or cover, placement timber
or brush piles to augment cover, or placement of structures
to provide nesting and resting sites may improve site
attractiveness for seed dispersing fauna on both upland and
wetland sites. Implicit in the the use of these techniques
is the assumption that they are cost-effective, that the cost
of adding structure will be more than paid for in the benefits

176
derived. Further study and analysis will be required to make
that determination, as the issue was not addressed in this
dissertation.
In addition to seed dispersal, animals serve many other
functions in the community such as pollination, nutrient
cycling, and substrate turnover. The fire ant study
demonstrated the beneficial effects of soil fauna on chemical
and physical properties of overburden soils. Recovery of
ecosystems after severe disturbance includes re-establishing
the below-ground community and processes, and coupling the
above-ground succession with the below-ground succession.
Reclamation activities should encourage the formation of a
diverse soil fauna. Factors likely to contribute to the
return of a rich soil fauna which can be easily incorporated
into a reclamation design include: (1) vegetation of high
species richness, (2) a high plant cover, and (3) a widespread
and thick litter layer over at least part of the area, and the
presence of some logs and standing dead wood. For example,
specific plantings can help with the first two items and
trees, topsoil, litter and woody debris from the pre-mining
land-clearing operations can be stockpiled and reused later
to create litter patches, brush-piles and downed logs.
Self-Organization
In the self-organization paradigm, the actual species
composition of the community is a function of the system's

177
self-organizing choices. It is believed that diversity
stabilizes many ecosystem during environmental fluctuations
or other periods of potential stress, buffering the system by
providing more self-organizational choices, that extend the
range of environments in which community structure and
processes, such as energy flow, can be maintained.
Seed/propagule banks and accumulated below-ground
structures (e.g., roots, rhizomes) provide a storage of
"choices" for all environmental contingencies, providing some
support for the self-organization paradigm. In wetland and
upland communities, seed banks provide a mechanism for rapid
recovery from catastrophic mortality resulting from fire,
clear-cutting, and drought. The rapid response of seed banks
to environmental change minimizes interruptions to the energy
flow in the community helping to maximize overall primary
production. A relatively continuous flow of energy through
an ecosystem, even during recovery periods, prevents an
uncoupling of the above-ground and below-ground components,
since many rhizosphere processes depend upon energy inputs
from the above-ground community.
It appears that many mature, self-maintaining wetland and
upland systems contain a sufficient number of "choices" to
meet a variety of environmental contingencies. Duplicating,
or mimicking the "choices" found in many natural ecosystems
by incorporating diversity into reclamation may prove to be
a valuable design principle for creating self-maintaining

178
systems. The reclamation design principle then is to create
wetland and upland systems that contain (1) a variety of
habitat conditions with a variety of soil types and soil
moisture conditions, and some variation in microtopography;
(2) a diverse assemblage of plants with many representatives
of all life history strategies; (3) habitat conditions needed
to enhance the formation of a diverse soil fauna; and (4)
habitat conditions needed to enhance the use of the site by
a diverse assemblage of wildlife. Once the reclamation effort
has provided a diverse array of choices, then the system can
"choose" the actual species composition of the community.

CONCLUSIONS
The following points summarize the major conclusions relating
to the wetland and upland field studies and their implications
for reclamation and the paradigms of succession:
1. The application of muck from a donor wetland provides not
only a propagule bank of seeds and rhizomes but structure
in the form of the organic material itself and its
attendant microbial and microfaunal component.
2. The development of the seed bank within the wetland, as
seen by the spread of bulrush and Sagittaria.
demonstrates the workings of an autogenic process and
may provide one measure of community maturity. The
spread of bulrush and Sagittaria also indicates that
emergent macrophyte species other than cattail are
capable of invading open mineral soils in reclaimed
marshes.
3. The studies of wetland community development at Fort
Green show that the marsh communities resulting from the
muck treatment had a different species composition than
those arising by natural succession. These community
differences also proved to be stable for the first four
growing seasons.
179

180
4. Under appropriate conditions, even slow-dispersing marsh
species are able to become established and occupy the
available space. Once the available space is filled,
opportunity for invasion, even by aggressive weedy
species like cattail, is limited.
5. Marsh studies at the Fort Green site have shown the value
of documenting specific site histories, beginning if
possible with an unvegetated substrate. Long-term
studies provide the best view of ecosystem development.
6. The Gleasonian model proposed by van der Valk (1981)
appears to have merit as a partial descriptive paradigm
of wetland species composition in secondary succession.
It does not recognize the autogenic processes that can
feedback to and influence the "environmental sieve."
7. Evidence was found in the upland tree seedling plots to
support the operation of all paradigms: inhibition,
initial floristics, relay floristics, coevolution, and
self-organization. A unified paradigm that the ideas of
all five paradigms will provide an eclectic resolution
to the controversy.
8. Field studies show that mound-building ants can influence
soil structure, runoff and soil infiltration, nutrient
cycling, plant growth, and plant species distribution.
Similar effects have been documented for the soil fauna
in other ecosystems.
The arrested succession observed by many researchers on
9.

181
mined lands may be largely attributable to restrictions
on dispersal. Late successional plant species in marsh,
swamp and upland ecosystems can become established, grow,
and survive under early successional conditions. The
successional process on disturbed lands can be influenced
and enhanced by facilitating dispersal and adding the
more slowly arriving components.
10. The upland forest seed plots show that good germination
results can be obtained with direct seeding. Until
recently, the industry has not had much success with
getting seeds to germinate and survive. While direct
seeding of woody plants has been shown to be feasible,
it has not been demonstrated to be a cost-effective
reclamation technique. Very small seedlings appear to
be more vulnerable to stress and mortality than larger
seedlings.

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BIOGRAPHICAL SKETCH
Mr. Dunn was born on January 23, 1954, in Summit, New
Jersey. After completing elementary and secondary education
in New Providence, New Jersey, he entered Tufts University in
1972, where he majored in biology and received the Bachelor
of Science degree in May 197 6. From May 197 6 through
September 1977, he was employed as an herbarium assistant in
the Phippen-Lacroix Herbarium at Tufts University. His
graduate training began at the University of Florida in the
fall of 1977. He took a leave of absence from his graduate
studies to work in environmental consulting in 1979 and 1980,
then returned to complete the requirements for the degree of
Master of Science in botany in 1981. In 1981, Mr. Dunn
entered the Environmental Engineering Sciences Department at
the University of Florida as a doctoral candidate. In the
fall of 1985, he joined Environmental Services and Permitting,
Inc., as a senior scientist. He moved to the environmental
consulting firm of CH2M HILL in 1986 and currently works as
an environmental scientist with project management
responsibilities in the areas of tertiary wastewater treatment
using wetlands, water quality investigations, and general
water resources issues.
He is married to Elizabeth Bondy. They have two handsome
sons, Charlie and Sam.
193

I certify that I have read this study and that in my
opinion it conforms to acceptable standards of scholarly
presentation and is fully adequate, in scope and quality, as
a dissertation for the degree of Doctor of Philosophy.
G. Ronnie Best, Chairman
Associate Research
Scientist,
Environmental Engineering
Sciences
I certify that I have read this study and that in my
opinion it conforms to acceptable standards of scholarly
presentation and is fully adequate, in scope and quality, as
a dissertation for the degree of Doctor of Philosophy.
Howard T. Odum
Graduate Research
Professor,
Environmental Engineering
Sciences
I certify that I have read this study and that in my
opinion it conforms to acceptable standards of scholarly
presentation and is fully adequate, in scope and quality, as
a dissertation for the degree of Doctor of Philosophy.
Environmental Engineering
Sciences
I certify that I have read this study and that in my
opinion it conforms to acceptable standards of scholarly
presentation and is fully adequate, in scope and quality, as
a dissertation for the degree of Doctor of Philosophy.
Professor,
Forest Resources and
Conservation

I certify that I have read this study and that in my
opinion it conforms to acceptable standards of scholarly
presentation and is fully adequate, in scope and quality, as
a dissertation for the degree of
Warren Viessman
Professor,
Environmental Engineering
Sciences
This dissertation was submitted to the Graduate Faculty
of the College of Engineering and to the Graduate School and
was accepted as partial fulfillment of the requirements for
the degree of Doctor of Philosophy.
May, 1989
Dean, College of
Engineering
Dean, Graduate School



162
Crusts commonly develop on the surface of overburden
soils as they are alternately exposed to wetting and drying.
The crust reduces infiltration and increases runoff relative
to those areas where the crust has been broken. Crusting
causes rainfall to pond on the soil surface, and blue-green
algal mats commonly form on the most frequently ponded areas.
Algal mats provide an additional barrier to water
infiltration.
Ehlers (1975) found that earthworm burrows reaching the
surface improve water drainage. Ursic and Esher (1988)
demonstrated that small mammal burrowing significantly
increased water detention-retention in a pine-covered
catchment and concluded that the numerous interconnected
surface and subsurface burrows created a system that could
accept and retain rain water until it was transmitted to
deeper layers or moved into the soil matrix. In simulated
rain study plots with short-tailed shrews (Blarina
carolinensis) and pine voles (Pitvmvs pinetorum), they showed
that burrowing activities decreased surface runoff by
approximately 25 percent.
Ant tunnels are soil macropores. Dixon (1971) concluded
that large pores can have a profound effect on the
infiltration of water into soils. In a model developed to
study pore size in relation to infiltration, Edwards et al.
(1979) demonstrated that surface-connected holes can


110
Table 12e. Ouercus.
Treatment Means
Plot Assignments
PR>F
Weeded
Natural
Enhanced
for ANOVA (ANOVA)
Legume Colonizers
Plots 15 & 18
7.81
6.26
6.19
5.63
Neglected
.0011
A
B
B
B
Plot 15 Weeded,
8.17
6.26
6.19
5.63
18 Neglected
.0001
A
B
B
B


173
community at Fort Green was found to be a function of the
interplay between the propagules available and the prevailing
environmental conditions.
The formation of a seed bank in created wetlands appears
to be a relatively rapid process, beginning almost immediately
after the land surface has been exposed, but the species
present in the seed bank samples were predominantly the
initial colonizing species. Notably absent were seeds of the
late successional species: woody taxa, emergent macrophytes,
submergent macrophytes, and free-floating aquatic species.
The implication of the initial floristics paradigm for
reclamation design is that within certain constraints the
species composition of reclaimed upland and wetland
communities can be influenced, an in particular late
successional species can often be established from the start.
For wetland systems, design should focus on the seed/propagule
bank as a critical component of self-maintaining systems. The
use of peat or muck from donor wetlands can provide an instant
seed bank that contains seeds/propagules of early and late
successional species. As shown by the success of the bulrush
plantings at Fort Green, some perennial macrophytes can be
easily established by planting. A diverse array of woody
species can be successfully established by seedling plantings
in both wetland and upland situations.


115
Table 14. Results of vasey grass growth bioassay on mound and
non-mound soils from 1-, 2-, and 5-year old sites.
Site
(age)
Seedling
Growth
Parameter
Mean
Mound
Soil
Non-mound
Soil
P
Tiger Bay
(1 year)
Below ground
biomass (g)
0.242
0.139
. 002
Above ground
biomass (g)
0.386
0.162
.0005
Total
biomass (g)
0.626
0.301
. 0006
Fort Green
(2 year)
Below ground
biomass (g)
0.233
0.145
.0003
Above ground
biomass (g)
0.226
0.153
.004
Total biomass
(g) 0.459
0.298
.0004
Clearsprings
(5 year)
Below ground
biomass (g)
0.284
0.172
.0001
Above ground
biomass (g)
0.308
0.160
.0003
Total
biomass (g)
0.592
0.332
.0001


Figure 15. Percent cover by Pontederia cordata and Tvnha latifolia on marsh transects
at Fort Green in fall 1982; spring, summer, and fall 1983; spring, summer and fall 1984;
and summer 1985 at (a) transect 97, (b) transect 105, (c) transect 139, (d) transect
115, (e)transect 125, and (f) transect 130.


55
Chemical Soil Analyses
To test the hypothesis that the activity of the fire ants
changes the chemistry of the mound soil relative to the nearby
soil, paired soil samples were taken at the Tiger Bay, Fort
Green, and Clearsprings reclamation sites. Each reclamation
area consisted of recontoured overburden. Six paired samples
were taken, each pair consisting of a mound sample and non
mound sample from 1 m away, were taken at each site. All
samples were taken with a bucket auger and stored in plastic
bags at 5 C.
Samples were air dried and sifted through a No. 20 mesh
sieve to remove ants from the mound soils. A subsample of
approximately 100 g was taken from the sieved samples to be
used for chemical analysis. The remaining soil was composited
to yield single mound and non-mound sample from each of the
three sites. The composite samples were used for greenhouse
experiments assaying growth differences between the two soils.
Individual soil samples were analyzed for pH, organic
matter content, total kjeldahl nitrogen (TKN), and selected
cations (calcium, magnesium, potassium, sodium, and
manganese).
pH measurements were made with a pH meter with glass
electrode in a 2:1 deionized water to soil dilution, using
10 g of air-dried soil mixed with 20 ml of distilled water.


ECOLOGICAL PARADIGMS, SPECIES INTERACTIONS, AND
PRIMARY SUCCESSION ON PHOSPHATE-MINED LAND
by
WILLIAM JAMES DUNN
A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMEMT
OF THE REQUIREMENTS FOR THE DEGREE OF
DOCTOR OF PHILOSOPHY
UNIVERSITY OF FLORIDA
1989


Figure 14. Depth exceedance curve for Fort Green wetland indicating the percent
inundation for each elevation over the time period August 1982 through December 1985.
-j


90
drought response. This indicates that macrophytes like
pickerelweed can become established in deep water areas and
muck application should be extended down to elevations with
an average depth of flooding of up to 1 m or more.
Large stands of pickerelweed developed only in the muck
treatment areas. Though it produced large numbers of seeds,
pickerelweed did not spread far from the areas of initial
establishment during the first four growing seasons.
Upland Succession Plots
Seed Germination and Survival
The experiment was originally designed as a nested
analysis of variance with a balanced design (i.e., equal
replications for each treatment). A sampling mistake during
the second weeding event (May) changed this plan, when plot
15 was weeded instead of plot 18. The error was not
discovered until the third weeding (June), at which time it
was decided to continue weeding plot 15. This change created
some difficulties as to the treatment status of plots 15 and
18. To incorporate plots 15 and 18 into the analysis, the
analysis of variance (ANOVA) for each species was carried out
using two different assignments for the plots: one analysis
with plot 15 assigned to weeded treatment and plot 18 dropped
and a second analysis with both plots dropped. Analyzing the
data following the original plot assignments (15 to enhanced


The development of a reclaimed marsh was monitored over
its first four growing seasons. Results showed that while
very different plant communities developed with the
application of muck from a donor marsh as compared to natural
succession, both types of initially established macrophyte
communities remained stable throughout the monitored period.
Upland succession was enhanced with direct seeding and
seedling transplants in four treatments: natural colonization,
enhancement of natural colonizers, enhancement with legumes,
and weeding. Tree seedlings had better height growth in plots
in which the colonizing weeds were removed. Tests indicated
that the five paradigms investigated operated concurrently
during primary succession.
Fire ants (Solenopsis invicta) were the most commonly
observed invertebrate species on mined lands, with well
established populations within the first year after mining.
Mound densities on 1- to 5-year old sites ranged from 560 to
2,000 per hectare. Mound soils had higher concentrations of
sodium, potassium, total nitrogen, and organic matter than
the adjacent non-mound soils. In greenhouse experiments, a
grass and a woody plant exhibited enhanced growth on mound
soils. Water infiltration rates were 5 to 100 times greater
on mound soils than non-mound soils.
The view of the competing paradigms as mutually exclusive
was not supported. A unifying paradigm may be possible from
a more eclectic synthesis of the inhibition, initial
vii


Table 4
61
. Seed bank densities, species richness, and
Shannon-Weaver diversity index from Florida
wetlands and selected marsh studies from
temperate North America.
Mean #
seeds/m2
Number of
Species
Shannon-Weaver
Diversity Ji Source
Natural Systems. Florida
Bay Swamp
4,125
12
1.45
This study
Lake Kanapaha
SaccioleDis zone 156.000
38
2.64
Myers 1983
Amaranthus zone
28,000
17
1.72
Myers 1983
Echinochloa zone
30,000
13
0.98
Myers 1983
Pond zone
9,000
8
1.17
Myers 1983
Four Comers Marsh
Juncus-Pontederiazone
72,502
3
0.06
This study
Pasture Marsh
Juncus-Pontederiazone
41,250
4
0.26
This study
Unreclaimed Systems
Sanlan
Juncus-Polvaonum Marsh
62,250
6
0.30
This study
EichhorniaMarsh
12,040
5
0.86
This study
Reclaimed Systems
Four Comers Reclamation
Project
Mulched plot
33,000
4
0.05
This study
Planted plot
31,710
4
0.05
This study
Control plot
2,210
4
0.95
This study
Planted swamp plot
Clearsprings Reclamation
11,460
Project
4
0.30
This study
South Basin #1
7,375
16
2.03
This study
South Basin 42
11,300
13
1.92
This study
North Basin 9,880
Fort Green Reclamation Project
14
1.88
This study
Mulched, vegetated
3,334
4
1.11
This study
Mulched, unvegetated
1,877
5
0.84
This study
Unmulched
3,920
6
1.38
Thisstudy
Other Natural Systems
Iowa, Prairie
glacial marsh 20
-40,000
7-16
Not calculated van der Valk
and Davis (1976, 1978)
Ontario, Lakeshore
marsh 9
-20,000
31
Not calculated Keddy and
Reznicek (1982)
New Jersey, Freshwater
tidal marsh 6-
32,000
12-20
Not calculated
Leek and
Graveline (1979)


I certify that I have read this study and that in my
opinion it conforms to acceptable standards of scholarly
presentation and is fully adequate, in scope and quality, as
a dissertation for the degree of
Warren Viessman
Professor,
Environmental Engineering
Sciences
This dissertation was submitted to the Graduate Faculty
of the College of Engineering and to the Graduate School and
was accepted as partial fulfillment of the requirements for
the degree of Doctor of Philosophy.
May, 1989
Dean, College of
Engineering
Dean, Graduate School


167
biologically mediated soil turnover on plant growth (Gentry
and Stiritz, 1972; Platt, 1975).
The effects of ants in a developing post-mining landscape
will not be limited to the role of fire ants, as other soil
fauna with both similar and different life histories are also
present on these sites. In addition, the composition of the
soil faunal community will likely change through time.
Fire ants are an exotic species but do not appear to
serve an exotic function. While they are able to displace
other native species of ants, in their absence the native
species can occupy these sites and serve the same function.
Some other ant species may influence the developing ecosystem
in similar ways at different stages.
It is expected that as the post-mining landscape matures,
ants may decline in dominance while earthworms gradually
become more important components of the soil microfauna. Ants
and earthworms may perform much the same function at different
stages of succession. The two intensify different stages of
decomposition; ants mainly with the first stages of
mineralization and earthworms with humification. Petal (1978)
has argued that the contribution of these two groups of
animals to processes within the ecosystem and the range of
their influence are functionally equivalent in environments
with different fertility, plant productivity, rate of
decomposition, and trophic complexity. In infertile soils
with low organic matter and decomposition rates, like young


Abstract of Dissertation Presented to the Graduate School
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Doctor of Philosophy
ECOLOGICAL PARADIGMS, SPECIES INTERACTIONS, AND
PRIMARY SUCCESSION ON PHOSPHATE-MINED LANDS
By
WILLIAM JAMES DUNN
May 1989
Chairman: Dr. G. Ronnie Best
Major Department: Environmental Engineering Sciences
Field studies on phosphate-mined lands were undertaken
to evaluate several paradigms for explaining succession,
including inhibition, initial floristics, relay floristics,
coevolution, and self-organization. Primary objects of study
were wetland seed bank formation, formation and stability of
wetland macrophyte communities, interactions between
colonizing species and trees on upland sites, and the role of
mound-building ants in upland succession.
A survey of natural and post-mining wetlands showed seed
banks develop rapidly, but contain only wind-dispersed early
successional species. Late successional marsh species can be
added as an instant seed bank through muck material from a
donor or, in some cases, by planting.
vi


RESULTS
Marsh Development
Seed Bank Survey
Results are presented in four general areas: seed bank
density, species importance values, floristic similarity
between samples, and species diversity of samples.
Seed bank densities. The mean number of seeds
germinating in samples from natural, reclaimed, and
unreclaimed marshes in central Florida ranged from 1877 to
72,500/m2 (Table 3). For comparison, seed bank studies of
natural wetlands from Florida, Iowa, New Jersey, and Ontario
have shown a range of density from 6,000 to 156,000 seeds/m2
(Table 4) The overall range of seed bank size (density)
covers three orders of magnitude; the lowest density is
1877/m2 in the sample mucked-unvegetated zone at Fort Green
and the high value is 156,000/m2 from the Sacciolepis striata
zone at Lake Kanapaha, Florida.
The range for natural wetlands samples is 4,000 to
156,000 seeds/m2, with the lowest value from the Peace River
bay swamp (the only forested wetland sample) and the high
value again for the Sacciolepis zone at Lake Kanapaha. A
trend evident in the results from studies at Lake Kanapaha is
59


Ill
Table 12f. Cabbage
palm
(Sabal
palmetto).
Treatment
Means
Plots 15 & 18
Neglected
NS
8.14
A
8.65
A
7.09 7.67
A A
Plot 15 Weeded,
18 Neglected
NS
8.23
A
8.65
A
7.09 7.67
A A


191
Ursic, S. J., and R. J. Esher. 1988. The influence of small
mammals on stormflow responses of pine-covered catchments.
Water Res. Bull. 24:133-139.
Ulanowicz, R. E., and W. M. Kemp. 1979. Toward canonical
trophic aggregations. Am. Nat. 114:871-883.
van der Valk, A. G. 1981. Succession in wetlands: a
Gleasonian approach. Ecol. 62 (3):688-696.
van der Valk, A. G. and C. B. Davis. 1976. The seed banks of
prairie glacial marshes. Can. J. Bot. 54:1832-1838.
. 1978. The role of seed
banks in the vegetation dynamics of prairie glacial
marshes. Ecol. 59(2):322-335.
Vogel, W. G. and W. A. Berg. 1973. Fertilizer and herbaceous
cover influence establishment of direct-seeded black locust
on coal-mine spoils. In R. J. Hutnik and G. Davis (eds.),
Ecology and Reclamation of Devastated Lands, vol. 2.
Gordon and Breach, New York.
Wade, D., J. Ewel, and R Hofstetter. 1980. Fire in South
Florida Ecosystems. U. S. Dep. Agrie., Forest Service
General Technical Report SE-17. 125 pp. Southeast. For.
Exp. Stn. Asheville, North Carolina.
Wadsworth, C. A. 1983. The development of techniques for the
use of trees in the reclamation of phosphate lands: A
project overview. In D. J. Robertson (ed.), Symposium on
Reclamation and the Phosphate Industry. Florida Institute
of Phosphate Research, Bartow, Florida.
Wali, M. K., and P. B. Kannowski. 1975. Prairie ant mound
ecology: interrelationships of microclimate, soils and
vegetation. In M. K. Wali (ed.) Prairie: A Multiple View.
University of North Dakota Press, Grand Forks, North Dakota
Wallace, P. M. 1988. The role of mycorrhizae in reclamation
of phosphate mined lands by ecological successional
processes. M.S. Thesis. University of Florida,
Gainesville.
Wallace, P. M., and G. R. Best. 1983. Enhancing ecological
succession: 6. succession of endomycorrhizal fungi on
phosphate strip mined lands. In 1983 National Symposium
on Surface Mining, Hydrology, Sedimentology, and
Reclamation. University of Kentucky, Lexington, Kentucky.


163
effectively transmit water when more water is applied than
can infiltrate.
Nutrient cycling. Results of the chemical analyses
support the hypothesis that foraging activity by ants elevates
levels of some nutrients in the mound relative to adjacent
non-mound areas. Confirmation of the nutrient concentration
role of mound-building ants is one of the central points of
a general model of the role of ants in ecosystem development
(see Figures 4 and 5).
Fire ants have been extensively documented because of
their status as nuisance pests. It is well established that
fire ants are general landscape foragers with a diet
consisting largely of protein from invertebrate prey
supplemented with oils and fats from some plant parts (Lofgren
et al., 1975). Foodstuffs are returned to the mound for
consumption by the colony. The conceptual model predicts that
because the ultimate fate of food materials is ant biomass and
waste products, the mound should have relatively higher levels
of organic matter and inorganic nutrients derived from
microbial breakdown of organic matter in the mound. Soil
chemical analyses showed enhanced nutrient pools in mounds
and, therefore, support that pathway in the conceptual model.
Generally higher levels of exchangeable cations,
particularly potassium, have been reported from ant mounds by
Czerwinski et al. (1969, 1971), Gentry and Stiritz (1972),


63
(33,000/m2), planted marsh plot (31,000/m2), and swamp planted
plot (11,300/m2). The lowest density found at the Four
Corners project came from the control plot (2,200/m2),
indicating that seed bank establishment is facilitated by
reclamation efforts.
Samples from the Fort Green project had the lowest and
narrowest range of densities (1,800 to 3,900/m2), but it
should be remembered that this project is only in its second
growing season. Surprisingly, the lowest density value from
Fort Green, and for all samples, came from an unvegetated
topsoiled (peat) area with open water. This may be a result
of the vagaries of sampling; alternatively, the seed bank in
the peat at this spot may be dominated by short-lived seeds
or species that only germinate under flooded conditions (which
were not duplicated in this study) or the topsoil material
(peat) may have been stockpiled (as is known to have occurred
with some peat material at this site).
Species importance values. As an estimate of the overall
influence or importance of each species in the seed bank
survey, modified importance value were calculated from the
density and frequency totals (Table 5) The importance value
is calculated by adding relative density and relative
frequency for each species, where relative density as the
density of the species divided by the sum of all densities,
and where relative frequency is defined as the frequency of


Table 18. Results of water infiltration tests on mound and non-mound soils at the
Fort Green reclamation area.
Soil Type
Infiltration Rate
Test
#1
Mound
Non-mound
Non-mound
(grass)
(algal mat)
11 cm/120 minutes
2 cm/120 minutes
1.5 cm/120 minutes
(0.09 cm/min)
(0.017 cm/min)
(0.012 cm/min)
Test
#2
Mound
Non-mound
(grass)
26 cm/60 minutes
1.5 cm/60 minutes
(0.43 cm/min)
(0.025 cm/min)
Test
#3
Mound
Non-mound
(grass)
>120 cm/20 minutes
1 cm/20 minutes
(>6.0 cm/min)
(0.05 cm/min)
123


48
Seedling plots
Seed plots
ptot with buffer
Figure 8. Schematic layout of seed and seedling transplant
plots on upland study site at Gardinier's Whidden Creek Mine
area.


27
1. Do the extended observations of succession support a
general theory of the successional process that is (a)
orderly, directional and predictable; (b) controlled by
biotic factors, (ie., autogenic); and (c) leads toward
an equilibrium state in either or both its biotic or
abiotic attributes?
2. Is the claim of some ecologists that successional
phenomena are reducible to theories of natural selection
justified? How do population theory and life history
strategies explain and predict ecosystem attributes?
3. What are the emergent properties claimed to justify
ecosystems theory? If population phenomena are not
additive, what is the measure of integration?
4. Does the evolution of ecosystems have any reasonable
explanation in evolutionary theory?
5. Is the reduction of ecosystem to trophic numbers, seen
by Hutchinson (1942) and Ulanowicz and Kemp (1979) as the
essence of the genius of Lindeman, holistic or simply a
collective property as stated by Salt (1979)? In what
sense is the ecosystem approach to succession holistic?
6. Can reasonably explicit distinctions be made between a
small-scale disturbance initiating the traditional serule
within the community and a large scale disturbance
initiating an earlier stage of a sere? Can autogenic and
allogenic disturbances be clearly distinguished or are
they interdependent, as suggested by White (1979)?
7. Can a theory of succession be developed to incorporate
a sere regularly reaching an equilibrium over an extended
area, as argued by Bormann and Likens (1979) and Franklin
and Henstrom (1981), and a sere that is largely
interrupted by disturbance as described by Raup (1957)
and by Heinselman (1981)? Can the achievement of
equilibrium be related to a trajectory toward
equilibrium?
Hypotheses and Objectives
Research for this dissertation involved nearly 4 years
of field work on mined lands in Polk County, Florida. The
main objectives were (1) to evaluate the process of initial


168
overburden soils, ants speed the return to the soil of
nutrients accumulated in the bodies of other animals. The
role of earthworms appears to be greater in fertile soils,
characteristic of more mature ecosystems, where they speed the
release of nutrients from the organic matter as it is being
decomposed.
Eclectic Synthesis of Paradigms and Implications for
Reclamation Design
Evidence reported in this dissertation supports the
conclusion that both allogenic and autogenic forces act to
change vegetation during primary succession on reclaimed
upland and wetland sites. An encompassing paradigm of
ecological succession must recognize the action of both forces
and the interplay or feedback between them. With regard to
the competing paradigms (initial floristics, inhibition, relay
floristics, coevolution, and self-organization), studies
reported here indicate that all are operating either
simultaneously or at some time during succession on mined
lands. It is likely that different paradigms may be
appropriate at different stages of ecosystem development.
There is no doubt that ecosystems can be studied either
by examining one mechanism at a time or with a holistic,
synthetic ecosystem approach and that valuable information is
contributed by both approaches. It is premature to assert
that a synthesis is not possible (Peet and Christianson,


36
Table 1. Sites used in marsh
ant study.
study, upland forest
study, and
Sites
Upland
Marsh Forest
Study Study
Ant
Study
Sanlan Marsh
X
Tiger Creek
Reclamation Area
X
Clearsprings Wetland
Demonstration Project
X
X
Whidden Creek
Reclamation Area
X
Four Corners Wetland
Demonstration Project
X
Fort Green Wetland
Demonstration Project
X
X
Natural Marsh
X
Peace River Bay Swamp
X


154
development and that the relatively slower-growing woody
species show less vigorous growth when faced with herbaceous
competitors. Because forest development is a long-term
process (on the order of 50 to several hundred years), the
experimental plots provide a very controlled view of only the
earliest stages. It is possible that the presumed benefits
of the early colonizers take time to accrue and have an
effect. The effect of litter may be an example.
Foresters have long noted competition as a factor
influencing successful reforestation. Tourney and Korstian
(1931) note that a low, dense cover of grasses and herbs is
a decided disadvantage to reforestation; not only does it pro
vide a retreat for rodents and other seed-eating animals but,
as soon as germination occurs, it directly competes with the
young seedlings. The roots of the herbaceous competitors draw
nutrients and water from the surface layers of the soil, and
the intensity of competition often proves fatal to the trees.
Competition has also been documented as a cause of
decreased establishment and growth of tree seedlings in
reclamation. Tackett and Graves (1983) cited competition by
an herbaceous cover crop as a significant factor in reducing
the height growth of tree seedlings. Vogel and Berg (1973)
also found competition from herbaceous plants could be
detrimental to growth of tree seedlings. Brown (1973) cited
competition from herbaceous plants as one of the factors
affecting germination and initial survival of seedlings.



PAGE 1

ECOLOGICAL PARADIGMS, SPECIES INTERACTIONS, AND PRIMARY SUCCESSION ON PHOSPHATE-MINED LAND by WILLIAM JAMES DUNN A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMEMT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 1989

PAGE 2

ACKNOWLEDGMENTS I thank my faculty committee members Dr. G. Ronnie Best, Dr. H. T. Odum, Dr. Clay Montague, Dr. Steve Humphrey, and Dr. Warren Viessman for their guidance. The research was supported by Florida Institute of Phosphate Research grant number 81-03-008, "Enhanced Ecological Succession Following Phosphate Mining," G. R. Best and H. T. Odum, principal investigators. Several mining companies provided support and information. Marsh studies at Fort Green were in part supported by Agrico Mining Company. Mobil Chemical Company, International Minerals and Chemical Company, Gardinier Phosphate Company, and W. R. Grace and Company provided access to study sites. Special thanks go to those who assisted with field work, Pete Wallace, Mel Rector, Alfonso Hernandez, Juan Hernandez, Bob Tighe, Jim Feiertag, and Tim King. The late Bill Coggins ran all the SAS analyses. Dr. Ron Myers allowed the use of unpublished data on seed banks at Lake Kanapaha. Maria Mittan helped with technical editing. I wish to thank CH2M HILL for making its resources available during the final phases of this dissertation. ii

PAGE 3

I sincerely thank my wife, Buffy, for her eternal patience and support during this degree. Finally, I thank my two sons Charlie and Sam for making life bearable during the "crunch." iii

PAGE 4

r •* . TABLE OF CONTENTS ACKNOWLEDGMENTS ii ABSTRACT vi INTRODUCTION 1 Previous Studies of Succession on Mined Land 2 Background and Concepts 3 Succession Theory 3 Wetland Succession 9 Role of Consumers 13 Competing Paradigms of Succession 20 Initial Floristics 20 Inhibition 20 Relay Floristics 24 Coevolution 24 Self -organization 24 Changes in Paradigms 24 Hypotheses and Objectives 27 Marsh Development 28 Upland Forest Development 29 Mound-building Ants and Ecosystem Development 30 Description of Study Sites 33 METHODS 43 Marsh Development 43 Seed Bank Survey 43 Marsh Transect Study 45 Upland Forest Studies 47 Direct-seeded Plots 50 Seedling Transplant Plots 51 Mound-building Ants and Upland Succession 53 Survey of Mound Density 53 Physical Soil Analyses 53 Chemical Soil Analyses 55 Plant Growth Study 57 Statistical Analysis 58 iv

PAGE 5

RESULTS 59 Marsh Development 59 Seed Bank Survey 59 Marsh Transect Study 72 Upland Forest Succession Plots 90 Seed Germination and Survival 90 Height Growth in Seed Plots 105 Height Growth in Transplant Plots 112 Mound-building Ants 114 Mound Survey 114 Plant Growth Study 114 Chemical Soil Analyses 116 Physical Soil Analyses 120 DISCUSSION. . . . i . ; 124 Marsh Development 124 Seed Bank Formation 124 Formation and Stability of Macrophyte Communities 126 Wetland Succession Model 132 Role of Life History Characteristics 132 Importance of Allogenic and Autogenic Factors 132 Eclectic Wetland Succession Paradigm 135 Upland Forest Succession Plots 139 Seed Germination and Survival 139 Height Growth 146 Species Removal 150 Competition 153 Succession 155 Caveats 157 Mound-Building Ants 158 Mound Survey 158 Ant Mound Roles 159 Ant Model 166 Eclectic Synthesis of Paradigms and Implications for Reclamation Design 168 Inhibition 170 Initial Floristics 172 Relay Floristics 174 Coevolution 174 Self-organization 176 CONCLUSIONS 179 REFERENCES 182 BIOGRAPHICAL SKETCH I93 V

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Abstract of Dissertation Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy ECOLOGICAL PARADIGMS, SPECIES INTERACTIONS, AND PRIMARY SUCCESSION ON PHOSPHATE-MINED LANDS By WILLIAM JAMES DUNN May 1989 Chairman: Dr. G. Ronnie Best Major Department: Environmental Engineering Sciences Field studies on phosphate-mined lands were undertaken to evaluate several paradigms for explaining succession, including inhibition, initial floristics, relay floristics, coevolution, and self-organization. Primary objects of study were wetland seed bank formation, formation and stability of wetland macrophyte communities, interactions between colonizing species and trees on upland sites, and the role of mound-building ants in upland succession. A survey of natural and post-mining wetlands showed seed banks develop rapidly, but contain only wind-dispersed early successional species. Late successional marsh species can be added as an instant seed bank through muck material from a donor or, in some cases, by planting. vi

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The development of a reclaimed marsh was monitored over its first four growing seasons. Results showed that while very different plant communities developed with the application of muck from a donor marsh as compared to natural succession, both types of initially established macrophyte communities remained stable throughout the monitored period. Upland succession was enhanced with direct seeding and seedling transplants in four treatments: natural colonization, enhancement of natural colonizers, enhancement with legumes, and weeding. Tree seedlings had better height growth in plots in which the colonizing weeds were removed. Tests indicated that the five paradigms investigated operated concurrently during primary succession. Fire ants ( Solenopsis invicta ) were the most commonly observed invertebrate species on mined lands, with well established populations within the first year after mining. Mound densities on 1to 5-year old sites ranged from 560 to 2,000 per hectare. Mound soils had higher concentrations of sodium, potassium, total nitrogen, and organic matter than the adjacent non-mound soils. In greenhouse experiments, a grass and a woody plant exhibited enhanced growth on mound soils. Water infiltration rates were 5 to 100 times greater on mound soils than non-mound soils. The view of the competing paradigms as mutually exclusive was not supported. A unifying paradigm may be possible from a more eclectic synthesis of the inhibition, initial vii

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floristics, relay floristics, coevolution, and selforganization models. viii

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INTRODUCTION -.i The pattern and process of ecosystem development, usually called succession, are a main focus of the science of ecology. The paradigms used to understand succession are still in controversy, and the pattern and process of ecosystem development are still much debated. A clear understanding of succession provides an opportunity for forming rational and cost-effective land reclamation techniques and policies that will enhance the successional process on disturbed lands. It is not possible to predict the long-term development of created and restored ecosystems without a clear understanding of the natural processes of ecosystem development. Unfortunately, the ecological literature remains divided on the fundamentals of succession, especially the interactions between early colonizing plant species and late successional species and the role of non-trophic interactions between producers and consumers. The establishment of vegetation is one of the first stages of primary succession on an abiotic substrate, whether the succession results from geologic uplift, glacial retreat, volcanic lava flow, landslide, or strip-mining. The postmining landscape is a relatively simple ecosystem of few 1

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2 species but provides a rich environment for testing paradigms describing the pattern and process of succession. Detailed ecological studies of the recovery process on mined lands may also identify some solutions to existing reclamation problems. The succession and human-managed reclamation of phosphatemined lands in central Florida provides and opportunity to evaluate successional theory and use the knowledge to facilitate reclamation. This dissertation examines successional processes on phosphate-mined lands, especially marsh development, upland forest development, and the roles played by seed banks and mound-building ants. In a few cases an understanding of wetland succession has been translated into a successful technique for wetland creation and restoration. In the Tampa Bay area it was observed that formerly unvegetated intertidal areas were quickly colonized and stabilized by smooth cordgrass ( Spartina alternif lora^ which presumeably helped mangrove seedlings to become established years later (Lewis 1982) . In 15 to 20 years the mangroves eventually shaded out the cordgrass and became dominant. Lewis developed a technique for establishing a nurse crop of cordgrass which has since become a common practice for mangrove establishment. Previous Studies of Succession on Mined Lands Many studies of unreclaimed mined lands have documented the paucity of late successional species on upland sites

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(Humphrey et al., 1978; Schnoes and Humphrey, 1987; Wallace, 1988) and wetland sites (Clewell, 1981; Rushton, 1983, 1988). Vegetation studies of phosphate clay settling ponds reported an initial cover of cattails (Typha sp.) and water hyacinths f Eichhornia crassipes) followed by primrose-willow f Ludwigia peruviana ) and willow (Salix caroliniana ) . Wax-myrtle ( Myrica cerifera) and vines dominated sites as they continued to dry (Zellars-Williams and Conservation Consultants, 1980; King et al. 1980; Rushton, 1983). These studies generally describe an arrested succession in which the initial species composition of primary invading species is perpetuated. In contrast, other studies (Kangas 1979, 1983) have described older sites where succession did not appear to be arrested or inhibited. In cases with a nearby seed source, sites were invaded by hardwood species such as red maple ( Acer rub rum ) , laurel oak ( Quercus laurifolia ) , and live oak ( Quercus virainiana) (Zellars-Williams and Conservation Consultants, 1980; Rushton, 1983). Background and Concepts Succession Theory Clements (1916) described succession as a universal, orderly process of progressive change. He asserted that the community developed from diverse pioneer stages to converge on a single, stable, mesophytic community (monoclimax) under

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the control of the regional climate. He held that in succession, the community repeated a sequence of stages, similar to the development of an individual organism from birth through death, that was an orderly directional process predictable in its development. As succession proceeded, the community increasingly controlled its own environment and, barring disturbance, became a self-perpetuating climax. Succession occurred as waves of plant populations made conditions suitable, or "prepared the way," for the next wave and often to the detriment of their own continued survival. To other ecologists of the time, the plant community was less well defined and succession less orderly, directional, and predictable than Clements suggested. Alternative concepts of succession voiced by Gleason (1917, 1926, 1939) advocated an individualistic, population-based approach in which the plant association is seen as a coincidence rather than an interdependent entity. The distribution of a particular species in the landscape depends on its migration characteristics and environmental requirements, and the plant community is an artifact solely dependent on the grouping of species with overlapping environmental requirements. Given sufficient time, all species had equal access to all sites, but species were found only on those sites with the appropriate environmental conditions. According to this allogenic theory, a particular species grows in the company of any other species with similar requirements and eventually

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5 disappears from areas where environmental conditions are no longer favorable. Egler (1954) also found fault with Clements' view of succession, but stressed the role of autogenic processes in old-field community succession. He applied the name "relay floristics" to Clements' sequential appearance and disappearance of groups of species and posed an alternative mechanism he termed "initial floristics" in which old-field plant community development after abandonment unfolds from an initial flora already residing within the soil, without additional increments by further invasion. As each successive species or group subside, another that has been present from the beginning, assumes dominance. In a forest succession sequence, eventually only the trees are left. Egler noted that the actual development of vegetation in an old-field is a function of both autogenic processes but that in secondary succession, initial floristics determined the composition of the resulting community and relay floristics played a relatively minor role. He also noted that allogenic factors were important determinants of community composition. The Clementsian and Gleasonian views of succession define opposite poles within the field of ecology. In the modern analogs, the arguments have been refined but many of the key issues and differences have remained intact. The Clementsian tradition has a modern synthesis in systems ecology, while the modern proponents of the Gleasonian view are typically aligned

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6 with the discipline of population ecology. Dichotomies still center on questions of holism versus reductionism, the evolutionary unity of communities, and whether ecosystems possess emergent properties. * ^ " ' ... ... ^ E.P. Odum (1969) provided a modern ecosystem reformulation of Clementsian succession. Odum noted the similarity of succession to the development of individual organisms and converged with Clements' description of succession as an orderly process that is reasonably directional and therefore predictable, resulting from modification of the physical environment by the community (autogenic) and culminating in a stabilized (climax, mature) ecosystem with homeostatic properties. Confusion developed when some ecologists described the ecosystem as having an evolutionary unity. Patten (1975) called the ecosystem a "coevolutionary unit." Webster et al. (1974) stated that a basic assumption of ecosystem analysis is that ecosystems are units of selection and evolve from systems of lower selective value to ones of higher selective value that optimize utilization of essential resources. Other ecologists did not view communities or ecosystems as evolutionary units because inheritance of genes is passed separately by the many species. H.T. Odum (1983) describes succession as a selforganizing process by which ecosystems develop structure and processes from the available choices supplied by seeding. The

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7 organization develops new programs for succession with which species prevail that are reinforced by controls and material cycles of the next larger system. This view has maximum power as a self -design principle, in that there is survival of those combinations of components that contribute most to the collective power of the system. Species combinations are reinforced that divide up and optimize the use of resources to collectively maximize productivity, and species substitutions occur through time as new choices are offered and selected. Some Darwinian selfish selection is involved but is regarded as secondary. Emphasis is on selection of relationships that make the system perform, with evolution ultimately occurring but on a longer time interval. Modern proponents of the Gleasonian individualistic view (Mccormick, 1968; Drury and Nisbet, 1971, 1973; Horn 1971, 1974, 1975; Pickett, 1976; Connell and Slatyer, 1977) find the classical Clementsian paradigm and its modern incarnation, the holistic-ecosystem representation, unpalatable. Mcintosh (1982) points out that the studies by these researchers share at least three characteristics : 1. They are commonly cited in recent discussion of succession as providing "new" insights for successional theory. 2. They are explicitly critical of Clements' holistic, organism theory of succession and of what they interpret as the successional theory of the organismic, holistic, ecosystem ecology expressed by ecosystem ecologists. 3. The alternative models of succession proposed advocate an individualistic, population-based approach emphasizing life history attributes of organisms and the consequence

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of natural selection as the essential basis of a modern theory of succession. Connell and Slatyer (1977) described three models by Which species may replace each other in a successional sequence. They assumed no further changes in the abiotic environment and that certain species usually appear first because they have the ability to produce large numbers of easily dispersed seeds, which are not adapted to germinating and growing on occupied sites. Model 1 assumes only certain early successional species are able to colonize a site immediately after disturbance, as in the "relay f loristics" model of Egler and the classical Clementsian view. Models 2 and 3 assume that any arriving species may be able to colonize, even those that typically appear late in the sequence. These are alternative forms of Egler -s "initial f loristics" model. In model 2, early colonists neither increase nor reduce the rates of recruitment and growth of later successional species. Species that "appear" later in the successional sequence are those that arrived either initially or later but grew very slowly. In Connell and Slatyer 's model of initial f loristics, the sequence of species is determined solely by life history characteristics. In contrast, model 3 (termed inhibition) holds that once early colonists secure the available space and resources, they inhibit invasion by subsequent species and suppress the growth

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9 of those already present. Invasion is only possible when the dominating species are damaged or killed, thus releasing resources. In model 3, the tolerance of late successional species is important, as it allows them to survive long periods of suppression. Wetland Succession , Much of the debate on succession focuses on the factors controlling the course of community development. Controlling factors are typically grouped as autogenic, those generated by the biological community itself, or allogenic, coming from outside the biological community. In some views of succession (Clements, 1916, 1920) wetlands were considered a transient stage between aquatic communities and a terrestrial forest climax. In this concept, aquatic areas may gradually fill from sediment deposition and organic peat formation. Emergent macrophytes, shrubs, and trees gradually appear, and the community continues to transform the wetland site into a terrestrial one. Where sediment accumulation raises the ground elevation above water levels, a change to drier vegetation is observed. In wetlands where inorganic sediments are not being added and land is not being elevated, peat formation may not proceed beyond water levels (Odum, 1984) . In warm climates, organic matter oxidizes or burns in dry weather, arresting succession. Many wetland ecosystems in this sense are a form of climax.

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10 A major influence of Clements' ideas on wetland ecology was the tendency to interpret zonation patterns in wetlands as indicators of future successional trends. Succession in wetlands was viewed as a directional, autogenically-driven process leading inevitably to some terrestrial climax. Evidence leads to the conclusion that both allogenic and autogenic processes act to change wetland vegetation and that the Clementsian idea of a regional terrestrial climax for wetlands is often inappropriate. Van der Valk (1981) claims that Pearsall (1920) was one of the first to apply Clements' concept of succession to wetlands. The concept of the monoclimax was eventually replaced by Whittaker's concept of pattern climax (Whittaker, 1953), which was based on gradient analysis studies that documented the independent distribution of species along environmental gradients. The effect was to de-emphasize the successional interpretation of seres, or vegetative zones in the case of wetlands, and to focus on the correlation of plant species with specific types of environmental conditions. Van der Valk (1981) proposed a "new" definition of wetland succession, based on the ideas of H.A. Gleason (1917, 1926, 1939) , that did not presuppose the existence of a climax vegetation. Van der Valk defined succession as a change in the floristic composition of the vegetation of an area from one year to another which, is narrower than Gleason 's definition of it as any change, quantitative or qualitative.

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11 in the vegetative cover of an area. In the van der Valk model, succession occurs whenever a new species becomes established or an existing one is extirpated. The model is based on the life history characteristics of the wetland species and the interaction of the species with the prevailing environmental conditions (see Figure 1) . Van der Valk classified wetland plant species into 12 life history strategies based on potential life span, propagule longevity, and propagule establishment requirements. Under this scheme, each life history type has its own unique set of characteristics and associated responses to prevailing environmental conditions, which act as a "sieve" in determining the species composition of the wetland. As environmental conditions change, so does the action of the sieve and, therefore, the species present. The van der Valk model focuses on the wetland seed bank as the key biological component. The functional significance of seed banks lies in providing the plant community with an in situ means of regenerating from naturally occurring disturbances (Grime, 1978). Van der Valk (1981) and van der Valk and Davis (1976, 1978) have aptly documented and demonstrated the role seed banks play in the vegetation dynamics of prairie glacial marshes that undergo cyclic patterns of f looding-drawdown-drought . In prairie glacial marshes and other marsh systems (Keddy and Reznicek, 1982;

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c o ^ •H H (0 00 (0 a\ 0) H o u X 3 H > >^ s ^ n) 0) to o o M-l 9 O O CO 0) ^ > « 0) « c c 0) Id u > >1 r1 0) u u o o a D< O •H M •1'

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13 O W OCO < < Q. Q. c o •a (0 > w c a> E c o w > c UJ « ® o C Q ® .± u a> O K Q Q.UJ CO z O O LAN ATI »hUi UJ a > •c w 0) > w i ® w a> O V) < ^ Qa c w c (0 o ® E o H 2 >. _ > (0 c •* 3 O ffl c r O Co® vj < £L > 1 I I UI < Q. > _ w "a CO G a CO u c o < I C C >s °1 c o 0) ® a Q.
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14 Leek and Graveline, 1979), seeds remain dormant, yet viable, in the seed bank during periods in which environmental conditions are unfavorable for germination, growth, and development of the population. In wetland and upland communities, seed banks provide a mechanism for rapid recovery from catastrophic mortality resulting from fire (Johnson, 1975), clear-cutting (Marks, 1974), and drought (Myers, 1983). Marks (1974) has shown that the rapid response of pin cherry to clear-cutting in the Hubbard Brook ecosystem helped minimize the effect of canopy removal on nutrient losses from the ecosystem. Egler's initial floristic hypothesis portrays old-field succession as a seed bank response. The van der Valk wetland model can be reformulated using energy circuit language (Figure 2). Van der Valk's 12 life history categories are simplified to mudflat annuals, emergent macrophytes, and aquatic macrophytes. The actual composition of the wetland is determined by the interaction between the existing plant community, the propagules present, and environmental conditions. Logic switches are used to indicate the actions of the "environmental sieve." Role of Consumers Various roles are attributed to consumers in ecosystems beyond simple trophic relationships of herbivory and predation. These non-trophic interactions typically involve

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hypothesized feedback loops between species, termed indirect effects. Non-trophic interactions are concerned with ecosystem structure and function, which, according to the individual selection theories of traditional population ecology, are not subject to adaptive evolution. It has been suggested that heterotrophs regulate autotrophs and thereby control the rate of energy production ( O'Neil et al., 1975; Lee and Inman, 1975). Owen and Weigert (1976) asked the question, whether consumers maximize plant fitness, and developed a hypothesis that consumers, like pollinators, have a mutualistic relationship with plants. They suggested that plants may exploit consumers to increase fitness. If, through the action of consumers, a nutrient that is in short supply is made more available to the plant, the relatively small amount of photosynthate lost may be more than compensated. Mutualistic interactions may involve a direct trophic link, such as those just described, but other non-trophic interactions between species very much affect fitness but do not involve competition or predation. For example, intensive fiddler crab (Uca pugnax ) activity in the tall-form of saltmarsh cordgrass f Spartina alternif lora ) stands improves soil drainage, oxygenates marsh sediments, and increases belowground decomposition of plant-generated debris (Bertness, 1985) , all of which can affect the growth rate of the cordgrass .

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17 Population ecologists view non-trophic interactions as byproducts of the evolutionary process. Wilson (1980) described the problem as one in which traditional investigators within the discipline of population ecology assumed that the community structure was already in place. They then focused on relatively superficial forms of competition and predation, while ignoring the structure that actually determined the parameter values of the models. Productivity in ecosystems depends on recycling and conservation of nutrient resources. The actions of consumers may cause a nutrient in short supply to become relatively more available. When primary production is nutrient-limited, heterotrophic activity, which accelerates mineralization, may help increase it. The importance of heterotrophs as regulators of ecosystem processes far outweighs their importance as measured by calories or grams of matter, but rather lies in how their characteristics affect or regulate ecosystem processes (Chew, 1974; Odum, 1982). Numerous examples can be found of the regulatory role played by consumers. Vertebrate herbivores have been shown to increase productivity of grasslands (McNaughton, 1975) . Piatt (1975) showed the influence that badger mounds have on soil properties and the pattern and distribution of some plant species. Burrowing rodents can act as nutrient pumps, bringing materials to the surface from below (Abaturov, 1972) . In forest soils, litter accumulated and decomposition slowed

PAGE 26

18 when earthworms were removed (Witkamp, 1971) . Earthworms stimulated the growth of potted barley seedlings, possibly by increases in vitamin B^j (Atlavinyte and Dacinlyte, 1969) . Dung beetle activity was found to be almost as effective as mechanical mixing in enabling plants to benefit from the nutrient storages in dung (Bornemissza and Williams, 1970) . Leaf cutter ants (genus Atta) reduced primary productivity by reducing leaf area, but more than made up for that loss by returning materials to the soil (Lugo et al., 1973). Mound-building ants can produce localized concentrations of organic matter and nutrients, resulting in changes in densities of bacteria, fungi, and plants (Czerwinski et al., 1971) . They can affect the physical and chemical aspects of soil as well as the distribution of plants, bacteria, and fungi, and are important in making channels and burrows. Hopp and Slater (1948) felt ants could be as effective as earthworms in creating conditions for improved plant growth, while Thorpe (1949) indicated that ants may produce greater effects than earthworms. Shrikhande and Pathak (1948) reported that ants increased the organic matter content of soils second only to earthworms. Numerous studies have shown chemical differences between mound and nearby non-mound soils, with evidence of higher levels of exchangeable cations, micronutrients, nitrogen, phosphorus, and organic matter, as well as differences in pH and conductivity (Czerwinski et al., 1969, 1971; Gentry and

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19 Stiritz, 1972; Rogers and Lavigne, 1974; Wali and Kannowski, 1975; King, 1977; Petal, 1978; Levan and Stone, 1983; Culver and Beattie, 1983) . Enhanced nutrient levels in mound soils are attributed to microbially-mediated mineralization of organic waste products in the mound (Petal, 1978) . This is supported by the work of Czerwinski et al. (1971), who showed the abundance of bacteria and fungi in ant mounds is higher than in the surrounding soil. Mound-building ants profoundly alter the soil profile characteristics at their nest sites ( Baxter and Hole, 1967; Salem and Hole, 1968; Wiken et al., 1976; Wali and Kannowski, 1975; Alvarado et al., 1981; Levan and Stone, 1983). Mound soil has been shown to differ from nearby soil in bulk density, porosity, and infiltration capacity (Rogers and Lavigne, 1974; Rogers, 1972; Wali and Kannowski, 1975). Through their influence on soils, ants can affect microtopographic heterogeneity, which can influence species composition, standing crop, and successional status of the local vegetation (Petal, 1978; Rogers, 1974; Gentry and Stiritz, 1974; King, 1977; Culver and Beattie, 1983). Herbs flourish on abandoned nest sites of harvester ants (Gentry and Stiritz, 1972) and are known to affect seed distribution. Ants are known to alter seed shadows in deserts (Bullock, 1974; O'Dowd and Hay, 1980), mesic environments (Beattie and Lyons, 1975; Handel, 1987; Beattie and Culver, 1981), and tropical forests (Roberts and Heithaus, 1986) . Some plant

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20 species known as myrmeccochores have a food body on their seed that is eaten by ants, which then disperse the seeds while returning food materials to the mound. Competing Paradigms of Succession The preceding discussions have revealed five competing paradigms of succession: two individualistic, life historybased models (initial floristics and inhibition) and three holistic ecosystem models (relay floristics, coevolution, and self-organization) . An energy circuit language diagram of succession is shown in Figure 3a that includes early and late stage plants, seeding, and nutrient recycle. Additional controls and pathways are added to represent various paradigms for the interactions between early and late successional species (Figures 3b-3f ) . The concept of each paradigm is briefly summarized below. Initial floristics . Early and late successional species coexist with the same resources (Figure 3b) . The early species modify the site so that it is not suitable for their continued reproduction, but have no effect on the recruitment of late species. Inhibition . Early and late successional species compete for available space and resources, such as light, nutrients, and moisture (Figure 3c) . Rapidly dispersing, fast growing early species colonize available open space and capture available resources, inhibiting the establishment of later

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o u 01 2 -iJ B ^ *^ -H O . 4J * -H n (0 4-i N r-l 9 « -H O r-t V4 C b 3 4 O b O U 10 (4 OtM-l C « B « O O c 0) -H 0 01 U »4

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24 species. Slower growing late successional species can only become established when the early colonizers have been killed or disturbed. Relay floristics . Late successional species are unable to become established on bare ground; they arrive and become established only after some critical level of development has been reached (Figure 3d) . Late successional species gradually displace the early colonizing species. Competition for light results in poor growth and reproduction by early colonizing species, when later successional species are established. Coevolution . An expanded version of the relay floristics model that also recognizes a long-term relationship between species (e.g., feedback relationships between and among trophic levels) (Figure 3e) . Self -organization . Producers, consumers, and decomposers are linked in a dynamic feedback network in which each trophic level is composed potentially of many species. Actual species composition of the community is a function of the system's self-organizing choices, which reinforce those combinations that optimize the use of resources and maximize productivity (Figure 3f) . Controls and reinforcement are shown from animals and larger scale phenomena of the surrounding system. Changes in Paradigms The continuing contradictions about succession after many decades of study suggest that more may be involved than a

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25 straightforward, objective, scientific consideration. Ecology and the succession concept may be in the midst of a revolution (Mcintosh, 1983) and specifically a change in paradigms, which Kuhn (1970) has described as the way a scientific discipline progresses. A common and idealized image of a scientific discipline is that it is universal, objective, and unbiased, with free communication and mutual comprehension among its members. Historians of science show this to be a simplistic and inaccurate view, and discuss the hypothesis of the "invisible college" as the basis of the organizational patterns associated with major advances and changes in paradigms within a scientific discipline (Crane, 1972; Griffin and Mullins, 1972) . The invisible college hypothesis argues that any discipline, especially one in a state of change, is subdivided into loose networks of scientists with varying degrees of cohesiveness and continuity. According to Griffin and Mullins (1972) such networks conform to the following criteria: 1. Their members believe they are making major changes in concept or methodology and the word revolution is much in evidence. 2. Members do not consistently observe the attitude of disinterested objectivity typically associated with scientists and may be passionate and one-sided advocates of a "ruling theory." 3. There is commonly a close, even somewhat closed, informal communication network within the network. 4. One or more outgroups are typically recognized and increasingly opposed as the network becomes more tightly organized.

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5. A network is commonly identified with a leader who may provide intellectual and/or organizational coherence. The work that the network associates itself with generally has originated, or is centered on a particular place with a more or less well defined origin and time span . Some of the confusion and contradictions concerning succession may be attributed to a lack of understanding of the history and sociology of the succession concept and the origins and evolution of the competing paradigms, or conceptual models. Confusion often arises from ignorance, as proponents of a "new" view may be unfamiliar with early work in the field, current thinking within other groups in the field, or their nomenclature and terminology. The invisible college hypothesis may help explain the divergent positions in ecology specifically concerned with succession. A scientific community upholds an old paradigm in spite of its inadequacies and contradictions until a new and better one emerges and is accepted. The paradigms of succession appear to be flawed and a new paradigm will likely emerge from a more eclectic synthesis. It is clear that an explanation of the cause and mechanism of succession, and development of a reasonable consensus on a paradigm of succession, will require a careful analysis of the historical background, biases and premises, and philosophy of the idea and its practitioners, critics, and proponents. As a framework for formulating this bridging paradigm, Mcintosh (1981) provided a number of questions to be answered:

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27 1. Do the extended observations of succession support a general theory of the successional process that is (a) orderly, directional and predictable; (b) controlled by biotic factors, (ie., autogenic); and (c) leads toward an equilibrium state in either or both its biotic or abiotic attributes? 2. Is the claim of some ecologists that successional phenomena are reducible to theories of natural selection justified? How do population theory and life history strategies explain and predict ecosystem attributes? 3. What are the emergent properties claimed to justify ecosystems theory? If population phenomena are not additive, what is the measure of integration? 4 . Does the evolution of ecosystems have any reasonable explanation in evolutionary theory? 5. Is the reduction of ecosystem to trophic numbers, seen by Hutchinson (1942) and Ulanowicz and Kemp (1979) as the essence of the genius of Lindeman, holistic or simply a collective property as stated by Salt (1979)? In what sense is the ecosystem approach to succession holistic? 6. Can reasonably explicit distinctions be made between a small-scale disturbance initiating the traditional serule within the community and a large scale disturbance initiating an earlier stage of a sere? Can autogenic and allogenic disturbances be clearly distinguished or are they interdependent, as suggested by White (1979)? 7. Can a theory of succession be developed to incorporate a sere regularly reaching an equilibrium over an extended area, as argued by Bormann and Likens (1979) and Franklin and Henstrom (1981), and a sere that is largely interrupted by disturbance as described by Raup (1957) and by Heinselman (1981)? Can the achievement of equilibrium be related to a trajectory toward equilibrium? Hvpotheses and Objectives Research for this dissertation involved nearly 4 years of field work on mined lands in Polk County, Florida. The main objectives were (1) to evaluate the process of initial

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28 plant community establishment in wetland and terrestrial communities and interpret the results and observations through competing paradigms of succession (initial floristics, inhibition, relay floristics, coevolution, and selforganization) , (2) to determine the role played by moundbuilding ants in the developing community and assess this role with the prevailing paradigms, and (3) identify possible techniques for enhancing succession on strip-mined land. These overall research objectives were addressed in three separate but related field studies. Marsh Development Seed bank survey . As an initial step in understanding and enhancing the design of self-maintaining ecosystems, seed bank dynamics were examined. A survey was made (1) to assess the size and species composition of seed banks in selected marsh ecosystems from natural and post-mining landscapes, (2) to identify the ecological role and significance of seed banks in marsh community dynamics, and (3) to evaluate the feasibility of establishing marsh ecosystems by helping form seed banks. Marsh transect study . Transects were used to compare the herbaceous component of the wetland that developed from natural processes to that created by spreading muck from an onsite donor marsh. Stages of vegetation establishment were

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29 examined to test the hypotheses that (1) differences in the initial floristics in the two treatment areas (mucked versus unmucked) result in communities of very different species composition and (2) differences in the perennial macrophytes of the two different treatment areas would be maintained through time. * • Both seedbank and transect studies were used to evaluate the Gleasonian model of wetland succession proposed by van der Valk (1981) . Upland Forest Development Upland forest studies examined the relationships between early colonizing plants and late successional trees on an unvegetated upland site. The colonizing annuals, biennials, perennials, and low shrubs found on old fields were designated early successional species. The interactions between early and late species were examined to determine which paradigms explained ecosystem development (inhibition, initial floristics, or relay floristics) . Field plot experiments using species removal and addition were designed to determine the effect, if any, of colonizing vegetation on establishment, growth, and survival of tree species. Four treatments were used: (1) natural colonization, (2) enhanced colonization with seeds of several common old-field weeds, (3) addition of legume species, and (4) periodic weeding to keep the plots generally free of any colonizing

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30 vegetation. In both the enhanced colonization and enhanced legume treatments, the natural colonization process was also allowed to occur. Criteria for accepting or rejecting the competing paradigms are given below. 1. If seedlings grew better with either the enhanced colonization, natural colonization or legume treatments, then the initial floristics and inhibition paradigms were rejected in favor of the relay floristics paradigms. 2. If seedlings grew better in weeded plots, then the initial floristics and relay floristics paradigm were rejected in favor of the inhibition model. 3. If seedlings grew about the same in the weeded plot as in other treatment plots, then the relay floristics and inhibition paradigms were rejected in favor of the initial floristics. Mound-Building Ants and Ecosystem Development Early successional mined lands provide an opportunity to investigate interactions between species as the community is developing in a simple system with a few producers and a few consumers. Three field observations aroused interest in the role and effects of mound-building ants in such a system. First, fire ants (Solenopsis invicta) are one of the earliest arriving invertebrate consumers on young strip-mined lands. In central Florida, fire ant populations were usually well established in the first year after mining ceased. Second, herbaceous plants, especially grasses, growing on ant mounds were typically more robust, with a richer green color than plants found on adjacent non-mound soil. This

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observation led to the hypothesis that mound soils were more fertile because of the ants. Third, it was noted that overburden soils high in clay formed surface crusts that inhibited water infiltration, but mound building and tunneling by ants broke the surface crust and maintained the soil in a more friable condition. Fire ants are omnivorous scavengers who forage the landscape, gathering food materials and returning with them to the mound. This activity concentrates otherwise dilute nutrient materials, which may be one of the primary functions of ants in the ecosystem. If ant mounds represent a localized concentration of nutrients in the form of insect parts, plant parts, feces, and waste products, then they are also likely to be foci of microbial activity mineralizing organically bound nutrients. The ant colony and mound system may recycle materials that are scarce in the developing ecosystem. Mound-building ants may alter the soil profile and influence particle size distribution, bulk density, porosity, and infiltration capacity. These soil alterations may affect primary production. Relationships are shown in diagrammatic form. Arrows on a causal loop diagram of the ant model indicate pathways of influence (Figure 4). A "+" used at an arrowhead indicates an increase in the adjacent item. For example, a larger concentration of food materials in the mound leads to a higher level of microbial decomposers. A indicates a

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33 decrease in the item at the arrowhead. The ant model depicts two positive feedback loops, one linking plants-ants-microbes and one linking mounds-soil-water infiltration. The arrows represent causal relationships that can be experimentally evaluated. An energy circuit language formulation of the ant model (Figure 5) also provided a summary of ecosystem components and energy/material pathways for directing research efforts. Research questions were: 1. Do mound-building ants concentrate nutrients in the landscape? 2. If they do concentrate nutrients, does this provide a feedback to the primary producers (plants) , establishing a non-trophic interaction or indirect effect and eventually a feedback to themselves? 3. What function does mound-building work serve for the developing ecosystem? 4. If ants are found to provide positive feedback to the developing ecosystem, are there ways to further stimulate feedbacks and enhance succession? Description of Study Sites Eight study sites in central Florida were used in the three phases of the research (see Table 1 and Figure 6) . Seven of the sites were within Polk County and one in the northeast Manatee County in the Four Corners area. A brief description of each site is provided below. Pasture Marsh . This marsh was approximately 1.0 hectare in size and located on the Mobil Chemical Company's

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35

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Table 1. Sites used in marsh study, upland forest study, and ant study. Marsh Upland Forest Ant Sites Study Study Study Sanlan Marsh X Tiger creeK Reclamation Area X Clearsprings Wetland Demonstration Project X X Whidden Creek X Reclamation Area Four Corners Wetland X Demonstration Project Fort Green Wetland X X Demonstration Project Natural Marsh X Peace River Bay Swamp X

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37 Figure 6. Location of study sites in Polk and Manatee

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38 South Fort Meade Mine tract. The vegetation within the marsh was dominated by softrush ( Juncus effusus) , pickerelweed (Pontederia cordata) , Saaittaria lancifolia, and smartweed ( Polygonum punctatum ) . The marsh was selected as typical of the freshwater marshes within the study area, most of which are subject to grazing. Peace River Bavhead . This bay swamp is located on a seepage slope draining to the Peace River on Mobil ' s South Fort Meade Mine tract. The swamp had an overstory of sweetbay magnolia ( Magnolia virginiana ) , red bay ( Persea palustris ) , and dahoon holly ( Ilex cassine) . The groundcover consisted primarily of lizard ' s-tail ( Saururus cernuus ) . The substrate consisted of a layer of finely decomposed muck overlying fibrous peat. The depth of the organic soil averaged approximately 1 m. Sanlan Marsh . This marsh developed on an unreclaimed clay settling area that was mined in the early 1950 's. The site was selected because it was one of the few old, unreclaimed clay settling ponds that was not dominated by cattail, primrose-willow, or willow. Four Corners Demonstration Project . W.R. Grace Company initiated a wetland reclamation demonstration project at its Four Corners Mine site in 1979. Four 0.16-ha depressions were excavated to a maximum depth of 1.2 m in a pine-palmetto flatwoods adjacent to Alderman Creek in 1978. The area was not mined, but overburden was removed to a depth below the

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minimum design grade and then backfilled, simulating reclamation. Four test plots were established as follows: 1. Plot 1. Control plot, graded and left for natural revegetation. 2. Plot 2. Hand-planted with plant material taken from nearby natural marsh, including maidencane (Panicum hemitomon) , pickerelweed f Pontederia cordata) , and Juncus effusus. 3. Plot 3. Mulched 30 cm deep with donor muck from a nearby marsh. 4. Plot 4. Tree plot where 95 trees comprising 16 different species were transplanted from a donor site on Alderman Creek. Whidden Creek Reclamation Area . The Whidden Creek area was mined by Gardinier Phosphate in 1982 and 1983. The area was reclaimed in 1983 using an integrated landscape approach, that sought to create a small drainage basin discharging to Whidden Creek. Tiger Bay Reclamation Area . The Tiger Bay area was mined by International Chemicals and Minerals, Inc. (IMC) in 1982 and 1983. The area was reclaimed in 1983 as a land-and-lakes area typical of the industry's reclamation practice. Clearsp rinas Wetland Demonstration Project . Work on this 18-ha wetland demonstration project began in 1978. The project was a joint effort of IMC, the Florida Game and Freshwater Fish Commission, and the U.S. Fish and Wildlife Service. The site adjoins the Peace River and was designed to establish physical site characteristics similar to those that produce and maintain floodplain wetlands. Basins were

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40 created to encourage emergent plants, store water onsite, and create fish and wildlife habitat. Test plantings of 15 different tree species, planted as bare root seedlings were done in 26 plots with 400 trees per plot. Freshwater macrophytes were also planted in the basins. Fort Green Wetland Demonstration Project . This wetland project is part of a 148-hectare reclamation project carried out by Agrico Mining Company at its Fort Green Mine in southwestern Polk County (Figure 6) . The site, which was mined in 1978 and 1979, was recontoured to create 61 ha of wetlands and 87 ha of uplands (Figure 7) . The reclamation began in 1981 and was completed by May 1982. The project sought to create open water, freshwater marsh, freshwater swamp, and upland habitat. The site is gently sloping with a range of 40.23 m down to 35.40 m mean sea level (msl) in the wetland basin. The wetland basin receives runoff and baseflow from the surrounding uplands. The basin has a highwater discharge to the adjacent floodplain of Payne Creek when the surface water elevation reaches approximately 36.58 m msl. Within the wetland basin are several deep holes that serve as deep water habitat and aguatic refuge during times of drought. These deep pools have spot elevations ranging from 31.85 to 35.36 m msl. The donor muck was transported from a nearby donor marsh and spread in the littoral zone with depth varying from 2.5

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to 30 cm. Approximately 15 percent of the littoral zone received the muck treatment.

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METHODS Marsh Development Seed Bank Survey The seven wetland sites sampled in the seed bank survey include natural wetlands, and unreclaimed and reclaimed wetlands on mined lands (Table 2 and Figure 6) . At each site, one to several major vegetation zones were sampled with a 5-cm diameter, hand core sampler that was pushed into the substrate to the mineral soil layer. The depth of any overlying organic layer was noted, and only the upper 10 cm of the core was retained. Four individual cores were combined to yield a composite sample, with three composite samples taken in each vegetation zone selected. Samples were stored in sealed plastic bags at 4°C until they were processed. All live plant material was removed from the samples to prevent confusing in seed germination results with any vegetative regeneration. Once the plant material was removed, the samples were placed in wooden flats (25 cm x 25 cm) containing approximately 4 cm of sterilized gravel mixed with tailings sand; the samples were approximately 2 cm deep when spread out evenly in the flats. The flats were then placed 43

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outdoors in large plastic tubs containing sufficient water to maintain a saturated soil condition. Seedling emergence by species was monitored through time. Unidentified seedlings were counted, transplanted to flower pots, and allowed to mature until they could be identified. Marsh Transect Study Six permanently marked transects were established in October 1982: three each randomly located within the muck treatment areas and the unmucked, overburden areas (see Figure 7) . All transects began in the shallow littoral zone and extended upslope through the transition zone to the upland edge. The three muck treatment transects totaled 309 m and the three overburden transects totaled 275 m. The difference in total length of the two treatment groups was a result of the slope differences at the random locations. The plant communities along the transects were monitored using a modification of the standard line-intercept method (Phillips, 1959; Smith, 1980; Canfield, 1941) to record the percent cover by species along each transect. The standard method consists of taking observations along a transect line and noting the identity of any plant touched by an imaginary plane extending vertically above and below the transect line. The distance, or interval, of the planar intercept is also recorded. The individual intervals are totaled for each

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species to yield total cover, which can be standardized to percent cover. The modification of the standard method used in this study consisted of identifying patches or intervals of species occurrence even when the cover by the particular taxa within the patch was less than 100 percent. With this modified lineintercept technique, the interval distance as well as the percent cover by the taxa within the interval was recorded. The modification provided a more rapid method of measurement that was also relatively accurate and well adapted to measuring changes in vegetation across zones and following changes through time. The transects were sampled over four growing seasons: November 1982; May, July, and November 1983; March, July, and November 1984; and June 1985. Elevations along each transect were measured on 1.5 m intervals. These elevations were converted to mean sea level (msl) based on a reference to the measured surface water level in the wetland basin that day. A continuous water level record was provided by a surveyed, permanently mounted water level recorder. The daily summary values for the period of study were supplied by Agrico Mining Company.

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47 Upland Forest Studies An upland area on the west side of Parcel 6 at Gardinier Phosphate Company's Whidden Creek Mine (Figure 6) was cleared in late October 1983. The cleared area was 63 m by 63 m with a gentle slope from the south to the north. Seedling and direct-seeded plots were located in early December 1983 and two experiments were set up adjacent to each other (Figure 8) . The experimental design was a nested analysis of variance with four experimental treatments: colonizing species allowed, colonizers weeded out, colonizers added, and legumes added. Within each of the two experiments were four replicates for each treatment, for a total of 32 plots. All treatments were randomly assigned to plots. The experimental treatments used in both the seedling and direct-seeded plots were the addition of seed of four colonizing species, the addition of seed of four legume species, the removal of all colonizing species through weeding, and a natural invasion of colonizing species. The first two treatments involved the application of seed, which was completed just prior to planting the tree seeds or seedlings. The initial site clearing in October left all plots free of vegetation at planting time. The enhanced colonizer treatment included four of the most common species found on old fields and abandoned mine lands in central Florida: natal grass ( Rhynchelytrum repens ) ,

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48 S-eedling plots c C C w c w vv c c 1 L C W C L L E W L Seed plots E X w L w E C w L L c L E c E C X W E Enhanced colonizers L Legumes added C Natural colonizers allowed W Weeded 7in 7m a —dan g ptot witti buff tr SMd plot wMi buffsr Figure 8. Schematic layout of seed and seedling transplant plots on upland study site at Gardinier's Whidden Creek Mine area •

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49 groundsel ( Baccharis halimifolia ) , dogfennel ( Eupatoriuin capillifoliuin ) , and broomsedge f Andropogon virqinicus ) . Four species were added in the enhanced legume treatment: Cassia obtusifolia , Sesbania macrocarpa . Sesbania punicea , and Sesbania vesicaria. In the direct-seeded plots, 50 seeds of each legume were added for a total of 200 seeds per plot; 110 seeds per legume, totaling 440 seeds per plot, were added to seedling plots receiving this treatment. In both cases, the seeding rate gave a density of 22 legume seeds/m^. Seeds for the enhanced colonizer and enhanced legume treatments were applied by mixing the seeds with some overburden soil from the plot and hand broadcasting the mixture onto the plots. The soil was disturbed by hand with rakes and cultivators, to mitigate the effects wind would have on surface spread seeds of these wind-dispersed species. All plots were subsequently disturbed as part of a preplanting treatment. Planting and preplanting treatments were carried out in December 1983. The weeding treatment was administered quarterly in March, May, June, and September for both the transplanted and direct-seeded plots. All colonizing plants were hand-weeded and removed from the plots. Heavy rains in the first month after planting created several erosion rills running through the plots. To prevent cross contamination by seeds washing out of one plot and into another, hay was spread on the magins of all plots that had

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downslope neighbors. All major erosion rills on the site were mapped as an aid to interpreting results. In addition, several rills that had developed through the seed plots were diverted to interplot areas with a shallow, diversion trench. Once colonizing vegetation began to appear in early spring of 1984, it afforded a modest degree of soil stabilization and the severity of the erosion diminished considerably. Direct-Seeded Plots . Seeds of seven species were used in the direct-seeded test plots seeds: sweetgum ( Liquidambar styraciflua) . cabbage palm (Sabal palmetto ) , live oak ( Quercus virqiniana ) , laurel oak f Quercus laurif olia ) , southern magnolia ( Magnolia qrandif lora ) , sugarberry ( Celtis laevigata ) , and pignut hickory ( Carya glabra ) . These seven taxa were considered representative of common mesic hardwood species of central Florida. The seeding rate per plot was 50 seeds per species, yielding 350 seeds per plot. Each plot planting area was 9 m^ (3 m by 3 m) , resulting in a density of 39 seeds/m^. The plots were arranged in a 6 by 3 grid with two of the plots remaining unused (see Figure 8) . Treatments were assigned randomly to the plot grid. Each total plot was 7 m by 7 m, which allowed for a 2-m buffer all around the 9m^ planting area. The seed mix was hand broadcast onto the plots after the soil was disturbed, and the treatment seeds were

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i ' ., i ; . 51 added if required were. The plots were then raked lightly to incorporate the seeds into the substrate. The seed plots were measured in March and October 1984 and the species, height, and growth condition of each seedling in each plot was recorded. The location of each seedling was recorded as well so the fate of individuals could be followed. Seedling Transplant Plots In the seedling test plots, three mesic hardwood species were used: sweetgum, live oak, and cabbage palm. The planting stock for sweetgum and cabbage palm was 8 -month-old containerized seedlings grown in overburden soil. The oak seedlings were 1-month-old bare root seedlings. Ten individuals of each species were used in each of the 16 seedling plots, yielding 30 trees per plot and 480 seedlings total. Tree seedlings were planted after the soil was disturbed and any treatment seeds were added. The 3 0 trees were randomly assigned to the grid, and the same planting schematic was used in all the plots (see Figure 9) . The total area of each seedling plot was 8 m by 9 m, allowing for a 2-m buffer around an actual planted area of 4 m by 5 m. Seedlings were planted on approximately 1-m centers . The severe winter freezes of December 1983, and January February 1984 killed many of the planted seedlings. As the

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Seedlings planted on 1m centers C Cabbage Palm S Sweetgum L Live Oak Schematic for planting in Gardinier seedling plots.

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53 freezes occurred before any possible treatment effects could have been exerted, all of the f reeze-killed seedlings were replanted on March 27, 1984, which was then used as the starting date for growth measurements on the seedling plots. The plots were measured again in September 1984. At the time of measurement, the height of each seedling and growth condition were recorded. »< ; ^ j Mound-building Ants and Upland Succession Survey of Mound Density , Mound densities on the 1-year old IMC Tiger Bay site, the 2-year old Agrico Fort Green site, and the 5-year old IMC Clearsprings site were sampled. Replicate 5 m by 5 m plots were semi-randomly located at each site, and the location, diameter at base, height, general condition, and level of ant activity of each mound within each plot were recorded. Physical Soil Analyses Bulk density . Bulk density of mound and non-mound soils at the Fort Green Payne Creek site was sampled with a bulk density core sampler. Seven mound and seven non-mound samples were taken. The samples were oven dried at 103° C until a constant weight was attained, and the density was determined based on the volume of the sampler and its oven-dried weight.

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• T'igf^?!,?-'; ... 54 Infiltration tests . Soil water infiltration differences were measured at the Fort Green site using the paired inf iltrometer technique (Bertrand, 1965) . A metal cylinder, 16.5 cm in diameter and filled with water, was used to measure the rate of water intake of the soil. The metal cylinder was placed on the ground and driven into the soil with a rubber mallet to a depth of approximately 5 cm. A circular berm approximately 10 cm high and 60 cm in diameter was then created around the metal cylinder. The area enclosed by the berm served as the outer cylinder. Both cylinders were maintained at approximately constant head, or depth, by the addition of water. The amount of water lost through the inner cylinder over a measured time interval provided an estimate of the infiltration rate. The inf iltrometer test was not designed to measure absolute infiltration rates but rather as a measure of relative infiltration rates in side-by-side comparisons. Three such comparisons were made. The first used three inf iltrometers, with one placed over an ant mound, one on an adjacent grassed area typical of the site, and a third on a bluegreen algae flat. This test was run for 120 minutes. The second test, which lasted 60 minutes, compared the rates of another ant mound and another "typical" grassed area. The third test, which lasted 20 minutes, paired another mound and "typical" grassed area.

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55 Chemical Soil Analyses To test the hypothesis that the activity of the fire ants changes the chemistry of the mound soil relative to the nearby soil, paired soil samples were taken at the Tiger Bay, Fort Green, and Clearsprings reclamation sites. Each reclamation area consisted of recontoured overburden. Six paired samples were taken, each pair consisting of a mound sample and nonmound sample from 1 m away, were taken at each site. All samples were taken with a bucket auger and stored in plastic bags at 5° C. Samples were air dried and sifted through a No. 20 mesh sieve to remove ants from the mound soils. A subsample of approximately 100 g was taken from the sieved samples to be used for chemical analysis. The remaining soil was composited to yield single mound and non-mound sample from each of the three sites. The composite samples were used for greenhouse experiments assaying growth differences between the two soils. Individual soil samples were analyzed for pH, organic matter content, total kjeldahl nitrogen (TKN) , and selected cations (calcium, magnesium, potassium, sodium, and manganese) . pH measurements were made with a pH meter with glass electrode in a 2:1 deionized water to soil dilution, using 10 g of air-dried soil mixed with 20 ml of distilled water.

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56 Soil organic matter was determined by the Walkey-Black wet digestion method (Black, 1965) . Nitrogen was measured as TKN by the semi-micro kjeldahl procedure, a 1-g sample of air dried soil 7 ml of sulf uricsalicylic acid was added. After each sample was allowed to set for 30 minutes, 1 g of sodium thiosulfate was added and 2 g of catalyst were added. The samples were then heated in a block digester for 5 hours. After digestion, 20 ml of NaOH, 15 ml of boric acid, and 2 drops of indicator were added to each sample. The samples were then distilled to 60 ml, and titrated with 0.05 normal sulfuric acid. A dilute double acid solution (0.025 N H2S04 + 0.050 N HCl) was used to determine extractable levels of calcium, magnesium, manganese, potassium, and sodium. Cation levels in the extracts were measured by atomic absorption-emission on a Perkin-Elmer model 500 using standard operating techniques (Perkin Elmer, 1980). One ml of a 10,000 ppm (1%) lanthanum chloride (LaClj) solution was added to each dilution series of extract, which resulted in a 1000 ppm solution (.1%) in each sample. This procedure was necessary to control for interferences by silicon, aluminum, phosphate, and sulfate, which depress sensitivity in analyses for these cations. Equal amounts of lanthanum chloride were also added to standards and controls before analysis.

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. ' ./ 57 Plant Growth Study Several greenhouse experiments were set up to evaluate a potential growth difference between plants grown on mound and non-mound soils. The tests used a common early colonizing grass, vaseygrass ( Paspalum urvillei) , and a woody plant, sweetgum ( Liquidambar styracif lua ) , as the assay organisms. The composite soil samples, as described above, were used in the growth experiments. Ten plastic seedling tubes were filled from each of the six composite samples ten plastic. In each group of ten seedling tubes, five received a seedling of vasey grass and five received sweetgum. The tubes were placed in a greenhouse. At the end of 60 days, the seedlings were harvested and dried at 103° C to a constant weight. Each vasey grass seedling was subsequently divided into aboveand belowground portions that were weighed separately. The sweetgum seedlings were divided into root, stem, and leaf components, each of which was weighed separately. Leaf area of each sweetgum seedling was determined by making a xerographic image of the leaves, cutting out the individual images, and measuring leaf area with an automatic area meter.

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58 Statistical Analyses All statistical analyses were run with the Statistical Analysis System (SAS) . Data expressed as percent were transformed by the arcsine function.

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RESULTS ' " : ? : X Marsh Development Seed Bank Survey Results are presented in four general areas: seed bank density, species importance values, floristic similarity between samples, and species diversity of samples. Seed bank densities . The mean number of seeds germinating in samples from natural, reclaimed, and unreclaimed marshes in central Florida ranged from 1877 to 72,500/m (Table 3). For comparison, seed bank studies of natural wetlands from Florida, Iowa, New Jersey, and Ontario have shown a range of density from 6,000 to 156,000 seeds/m^ (Table 4). The overall range of seed bank size (density) covers three orders of magnitude; the lowest density is 1877/m m the sample mucked-unvegetated zone at Fort Green and the high value is 156,000/m' from the Sacciolepis striata zone at Lake Kanapaha, Florida. The range for natural wetlands samples is 4,000 to 156,000 seeds/m^ with the lowest value from the Peace River bay swamp (the only forested wetland sample) and the high value again for the Sacciolepis zone at Lake Kanapaha. A trend evident in the results from studies at Lake Kanapaha is 59

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60 C 10 CO T3 C (0 rH P 0) (0 4J 3 -H (0 4J C U (M (!) (0 IQ Q) £ •H Q. O) O (0 % * " rH V4 ^ <" ^ w ^ •a +i (u C 0)
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Table 4. Seed bank densities, species richness, and Shannon-Weaver diversity index from Florida wetlands and selected marsh studies from temperate North America. Natural Systems. Fl^rl-aa Mean # Number of seeds/m Species Shannon-Weaver Diversity^' Source 1-45 This study 2 . 64 Myers 1983 1.72 Myers 1983 0.98 Myers 1983 1.17 Myers 1983 0.06 This study 0.26 This study 0.30 This study 0.86 This study 0.05 This study 0.05 This study 0.95 This study 0.30 This study 2.03 This study 1.92 This study 1.88 This study 1 • 11 This study 0.84 This study 1.38 Thisstudy Not calculated van der Valk and Davis (1976, 1978) Not calculated Keddy and Reznicek (1982) Not calculated LecJc and Graveline (1979) Bay Swamp 4,125 12 Lake Kanapaha Sacciolepis zona 156,000 38 Amaranthus zona 28,000 17 Echinochloa zone 30,000 13 Pond zone 9,000 8 Four Comers Marsh JunmsPontederia zona 72,502 3 Pasture Marsh Juncus-Pontederia zone 41,250 4 Unreclaimed Svsr-Pms Sanlan JuncusPolVQonum Marsh 62,250 6 Eichhornia Marsh 12,040 5 Reclaim ed Systems Four Comers Reclamation Project Mulched plot 33,000 4 Planted plot 31,710 4 Control plot 2,210 4 Planted swamp plot 11,460 4 Clearsprings Reclamation Project South Basin #1 7,375 le South Basin #2 11,300 13 North Basin 9,880 14 Fort Green Reclamation Project Mulched, vegetated 3,334 4 Mulched, unvegetated 1,877 5 Unmulched 3,920 6 Other Natural sygt?T1f Iowa, Prairie glacial marsh 20-40,000 7-i6 Ontario, Lakeshore ^^sh 9-20,000 31 New Jersey, Freshwater tidal marsh 6-32,000 12-20

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that the species richness and size of the seed bank appear to decrease as the water depth increases in the Sacciolepis zoneAmaranthus zoneEchinochloa zone-Pond zone (Table 4) . For the wetland samples cited from outside Florida, the densities range from 6,000 to 40,000/m^, and for the three natural systems sampled in this study, the range of densities is 8,000 to 72,000/m'. The two marsh samples (Four Corners natural marsh and pasture marsh) had densities of 41,000/m' and 72,500/m*, respectively. The unreclaimed wetland sampled, the Sanlan marsh, had densities of 12,000/m^ and 62,000/m* from the Eichhornia and Juncus marshes, respectively. As with the Kanapaha samples, seed bank size apparently decreases with depth (water depth is more than a meter in the Eichhornia marsh) . The Sanlan samples, especially the Juncus Polyaonum zone with 62,000/m^, fall in the range of the natural wetlands already discussed, thus representing some of the higher densities encountered. This indicates that sizeable seed banks can develop in the absence of any reclamation efforts in post-mining wetlands. Wetland samples from reclaimed mine lands had a range of 1,800 to 33,000/m^, which is low to moderate by comparison to natural wetland systems. Samples from the three basins at Clearsprings ranged from 7,000 to 11,000/m^' at the Four Corners project, the range was 2,200 to 33,000/m^. More specifically, the treated plots had densities well within the range of the natural systems: topsoiled (peat) marsh plot

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63 (33,000/in^) , planted marsh plot (31, OOO/m') , and swamp planted plot (11,300/m^). The lowest density found at the Four Corners project came from the control plot (2,200/m^), indicating that seed bank establishment is facilitated by reclamation efforts. Samples from the Fort Green project had the lowest and narrowest range of densities (1,800 to 3,900/m'^), but it should be remembered that this project is only in its second growing season. Surprisingly, the lowest density value from Fort Green, and for all samples, came from an unvegetated topsoiled (peat) area with open water. This may be a result of the vagaries of sampling; alternatively, the seed bank in the peat at this spot may be dominated by short-lived seeds or species that only germinate under flooded conditions (which were not duplicated in this study) or the topsoil material (peat) may have been stockpiled (as is known to have occurred with some peat material at this site) . Species importa nce values . As an estimate of the overall influence or importance of each species in the seed bank survey, modified importance value were calculated from the density and frequency totals (Table 5) . The importance value is calculated by adding relative density and relative frequency for each species, where relative density as the density of the species divided by the sum of all densities, and where relative frequency is defined as the frequency of

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64 Table 5. Seed bank density data from Table 3 summarized across sites for species totals of density, relative density frequency, relative frequency, and importance value. Oanslty Total (mean l/m^) 1,126 Ralativ* Density Saapling Site Frequency Relative Frequency Importance Value AstgC subulata Baccharia halimifolia Carex sp. gyPQiTMS brevifolius Cvperus sp. Cvperus rotundua Cvoeraceae 459 125 500 2,209 12,207 84 gghingghlqa waiter^ 125 Eclipta ilhi 958 Eupatorium compositifol iiim 1,672 Graphalium obtusi folium Grasses, unknovm #1 unknown #2 unknown #3 Grasses, Grasses, Grasses, unknown #4 Grasses, unknown #5 1,625 Grasses, unkno%m #6 84 167 42 84 417 Hydrocotyl g verticillata Hypericuffl mutilum Jwgu? effusus s^MngVS bufonius Wwiqia viraata Ludwiaia palustris 126 42 206 257, 587 209 8,499 376 tiudwiqia leptocarpa 294 PglyggnUB Punctatun 8,588 Ptilimnium capillaeeuiB 1,168 BmSX vertleinaMi«f 42 gafflglua parviflonia 292 Scrophularia^T^a? ? 42 stgUaria msdia 334 Un3cnown species #1 5,334 #2 376 #3 2,750 0.36 0.15 0.04 0.16 0.70 4.00 0.03 0.04 0.30 0.50 0.03 0.05 0.02 0.03 0.13 0.50 0.04 84 0 3 0 0.02 0.07 00 07 00 12 Column total 308,000 0.09 3.00 0.40 0.02 0.09 0.02 0.10 1.70 0.10 0.90 100.00 0.20 0.20 0.07 0.13 0.20 0.53 0.07 0.07 0.27 0.60 0.07 0.13 0.07 0.07 0.20 0.07 0.13 0.07 0.13 1.00 0.20 0.47 0.13 0.13 0.67 20 07 13 07 07 27 20 0.20 7.07 2.80 3 . 16 2.80 2 . 95 0.95 0 . 99 1.90 2 . 06 2.80 3 . 50 7.50 11. 50 0.95 0.98 0.95 0.99 3.80 4 . 10 8.50 9 . 00 0.95 0.98 1.90 1.95 0.95 0.97 0.95 0.98 2 . 80 2.93 0.95 1.45 1:90 1.94 0.95 0.96 1.90 1.97 14.00 98.00 2.80 2.87 6.60 9.60 1.90 2.00 1.90 2.00 9.50 12.50 2.80 3.20 0.95 0.97 1.90 2.00 0.95 0.95 0.95 1.00 4.00 5.50 2.80 2.90 2.80 3.70 100.00 200.00

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65 occurrence of the species divided by the sum of all species frequencies. Both relative density and frequency were connected. With this type of calculation, both relative frequency and relative density are constrained to values between 0 and 100 percent, which produces an importance value for each species in the range 0 to 200. The most striking aspect of the calculations was the numerical dominance of soft rush (Juncus effusus) , which accounted for 84 percent of the germinating seeds in the study. It was also the only species found in all samples, yielding an absolute frequency of 1.0. The 20 species of highest importance value account for 92.5 percent of the total importance value (see Table 6). In fact, the four species of highest importance value soft rush, smartweed ( Polygonum punctatum ) , Cvperus rotundus, and Ludwiaia virgata account for 94 percent of the relative density and 66 percent of the total importance value. These four species can be considered the dominant species in this study and serve in general to characterize the seed banks sampled from central Florida. Florist ic similarity . Floristic similarity of seed bank samples was measured using the similarity index of Czekanowski for binary data. The index is defined as follows: Czekanowski ' s index = 2a/ (2a + b + c) where a = species common to sites 1 and 2, b = species found at site 1 but absent at site 2, and c = species found at site

PAGE 74

66 Table 6. Twenty species with highest importance values (IV) along with the relative density and relative frequency values used to calculate the IV. All data taken from Tables 3 and 4. % % Relative Relative Importance Species Density Frequency Value Juncus effusus 84 . 00 14 . 00 98 . 00 Polyqonum punctatum 3.00 9.50 12 . 50 Cyperus rotundus 4. 00 7.50 11. 50 Ludwiaia virqata 3.00 6. 60 9.60 EuDatorium compositif olium 0.50 8.50 9 . 00 Unknown 1 1.70 3.80 5.50 Eclipta alba 0.30 3.80 4.10 Unknown 3 0.90 2.80 3.70 Cyperus sp . 0.70 2.80 3.50 Ptilimnium capillaceum 0.40 2.80 3 .20 Aster subulata 0.36 2.80 3 . 16 Baccharis halimifolia 0. 15 2.80 2.95 Grass 4 0.13 2.80 2.93 . Unknown 2 0. 10 2.80 2.90 Juncus bufonius 0.07 2.80 2 .87 Cyperus brevifolius 0. 16 1.90 2.06 Ludwiaia palustris 0. 12 1.90 2.02 Ludwiaia leptocarpa 0.09 1.90 1.99 Samolus parviflorus 0. 09 1.90 1.99 Hypericum mutilum 0.07 1.90 1.97 185.00

PAGE 75

67 but absent at site 1. The index has a range of 0 to 1.0, where 0 represents complete dissimilarity and 1.0 represents complete similarity. There were few cases of high floristic similarity (Figure 10) . One was a comparison between the two natural marshes sampled and another between the Sanlan Juncus marsh and the Four Corners mulched plot, both of which compare samples of with low species richness. The other cases of high floristic similarity are within-site sample comparisons, one from Clearsprings and one from Fort Green. The Clearsprings samples had the largest number of species and had moderately high to high within-site floristic similarity. The species assemblage at Clearsprings had several unique or less frequently encountered species, including Aster subulata, Baccharis halimifolia . Eclipta alba , and Ptilimnium capillaceum. The samples from Fort Green also exhibited moderately high to high within-site floristic similarity, largely due to three species (soft rush, Ludwiaia virgata, and a species of Cvperus ) . Many comparisons of low to moderate similarity are noted, primarily because of the near ubiquity of soft rush and smartweed in all samples (Figure 10) . Species — diversity. Species richness and species diversity were compiled from data from this study and from Lake Kanapaha (Myers, 1983) (Table 4) . Diversity was

PAGE 76

« s a s I o & •H U 10 •H a 0 •H •P 10 •H u o 4 P (d li & CO s •H

PAGE 78

70 calculated using the Shannon-Weaver diversity index, given as H' and defined as H= (Pi m Pi) where Pi is the ratio of the number of individuals of the i"* species divided by the total number of individuals in the sample. The value of H' is influenced by two factors: the number of species, known as species richness, and the equitability with which the individuals of the population are apportioned among the species. The greater the species richness or the equitability the greater the value of H'. The overall range of H' values was 0.05 to 2.64; the lower value was from the mulched, vegetated plot at Fort Green and the highest from the Sacciolepis -zone at Lake Kanapaha. The latter sample also had the highest seed density (156,000/m^) and the highest species richness (38). The samples with the greater number of species typically had H' values in the upper range (see Table 4) . The most diverse natural wetland samples came from Lake Kanapaha and the bay swamp, while the highest diversity in the mined wetlands group was in the Clearsprings samples. In several cases (Four Corners natural marsh, pasture marsh. Four Corners mulched plot. Four Corners planted plot, and Sanlan Juncus -zone, the seed bank had relatively few species and was dominated numerically by soft rush. This situation more or less defined the low end of the H' range.

PAGE 79

Seed bank samples from all but the youngest sites in the post-mining landscape fall within or just below the range of densities and species diversity found in natural wetlands of Florida, Iowa, New Jersey, and Ontario. The indications from the results in this study are that it is possible for nature to reestablish a seed bank of approximately the same size and diversity as that occurring in some natural marshes, such as with the Juncus Polyqonum marsh at Sanlan (30 years old) . The time required for the seed bank to become a "reasonable facsimile" of a natural marsh as yet may be undefined. The results at Clearsprings indicate that modest sized seed banks with higher diversity can develop in 4 years with little actual marsh reclamation. With some reclamation efforts, seed banks that compare very favorably in size with natural marshes can develop in 5 years, as demonstrated at Four Corners. The seed banks in some of the post-mining wetlands do not appear to be different in size and species composition from the natural marshes sampled in this study. However, the actual vegetation present is not always as diverse, dense, or well developed, except in cases where muck (topsoil) from a donor wetland was applied. As an example, the results of lineintercept transects in mucked and unmucked areas of the marsh at Fort Green showed that the mucked areas to have 100 percent cover, while the unmucked areas had less than 30 percent cover.

PAGE 80

Marsh Transect Study ^-.^ Water levels and hvdroperiod . Daily water levels in the Fort Green wetland were summarized as mean monthly values for the period of the study, August 1982 to December 1985 (Figure 11) . Evident trends include the typical annual hydroperiod cycle and the drought that began in late 1984 and continued through late summer of 1985. The typical annual hydroperiod cycle began with low water in early winter followed by a rise in late winter or early spring and a spring peak. The cycle continued with a summer decline, a late summer peak, and a fall decline. With the exception of the 1985 drought cycle, the annual hydroperiod in the basin has typically varied about 0.3 m between lows of approximately 36.42 m msl to peaks of about 36.67 m msl. From the fall of 1984 through the spring 1985 a drought occurred that was unrelieved by spring rains. Water levels in the basin declined steadily from August 1984 to June 1985, when they reached a monthly low of 35.37 m msl. The late summer rains of 1985 brought the water level up to the typical late summer peak by August. The transect elevation data were used to generate individual transect profiles (see Figures 12 and 13). Four of the transects (97, 115, 125, and 130) began at elevations between 36.06 and 36.27 m, while transect 105 started at a lower elevation (35.60 m msl) and transect 139 started at a

PAGE 82

74 ^if^^^J:^' Elevation profiles of marsh transects 97, 105 and 139 with muck treatment zones indicated.

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75 37^ 1 36.5 E 36.0 35.5 37.0 TRANSECT 115 30 60 90 120 Tranaad OWvioa (m) 150 180 Figure 13. Elevation profiles of marsh transects lis, 125. and 130. '

PAGE 84

76 higher elevation (36.45 m msl) . Four of the transects ended at approximately the same elevation of 36.60 m msl. The remaining two transects (130 and 139) ended at approximately 36.80 m msl. The daily basin water levels for the period August 1982 to December 1985 were used to generate a depth exceedance relationship (Figure 14) showing percent of the time a given elevation was inundated. The graph shows a 1.2 m variation in water level during the study period; elevations below 3 5.51 m msl were inundated 100 percent of the time and areas above 36.73 m msl were never inundated. The curve slopes gently in the 80 to 100 percent inundation, range which covers a relatively broad range of elevations from 35.51 to 36.33 m msl. The 70 to 80 percent inundation zone covers a relatively narrower elevation range (36.33 to 36.45 m msl). The slope of the depth exceedance curve is fairly steep in the 0 to 70 percent inundation range (elevation 36.33 to 36.73 m msl) then flattens at the maximum inundation of 36.73 m msl. Emergent Macrophytes . The changes in cover of pickerelweed (Pontederia cordata ) and cattail (T ypha latifolia and T. domingensis ) on each of the six transects through each of the eight sampling periods were summarized from the lineintercept data. Pickerelweed and cattail were used because each was initially the dominant perennial emergent macrophyte in the mucked and unmucked zones, respectively. This

PAGE 86

78 dominance was consistent throughout the study (see detailed vegetation data in Appendix B) . The time series of cover changes for the two taxa (Figures I5a through 15 f) illustrate several aspects of the biology of the two species and differences in the marsh community development in mucked and unmucked areas. Pickerelweed became well established in the mucked zones of transects 97 and 105, but failed to reach the same level of development on any of the other four transects, including mucked transect 139. Conversely, cattail became well established on the overburden transects but lagged in colonizing those areas with well established stands of pickerelweed (transects 97 and 105) . Also, through the first few sampling periods, the sequence of stand establishment is evident for both taxa: (1) initial establishment of individual plants or clumps, (2) expansion of initial clumps, and (3) consolidation of clumps into larger patches or stands. Following the consolidation phase, most of the large clumps remained stable up to the drought of 1985. After the establishment phase, some movement and adjustment to other areas of the transect took place, especially in the case of cattail. This sequence of establishment is well demonstrated on transects 97 and 105 for pickerelweed (Figures 15a and 15b) and transects 115, 125, 130, and 139 for cattail (Figures 15c, 15d, 15e, and 15f ) . One particular difference between the two taxa is the vagility

PAGE 88

80

PAGE 89

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8 8 °8 ° 8 ° 8 ° (%)JM03 (%)JM03 (S)JMOO (%)JM03 (%)JMe3 (%) jmoq (%) jmoq (%)jmoo . » ' , i i * ! i ] f i 1 1 j

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83

PAGE 92

8 S IS -8 « 8 8 °8 = 8 °8 ° 8 ° 8 °' (%)jtMO (H)«MO (%)JM03 (%)JM03 (%)JM03 (S)JM03 (H)JMOO («)JM00 « i ! « i ^ ^ ! I i ' I i i i I ^ I ! I I Z J

PAGE 93

85

PAGE 94

86 of the propagules. Cattail has a very small, wind-dispersed seed; pickerelweed has a heavier, water/animal-dispersed fruit. On several of the transects, cattail was able to colonize new areas as they became available with the falling water levels of the drought of 1985. Cattail appeared more successful at expanding into open habitat than pickerelweed, but other taxa were equally opportunistic, especially bulrush (Scirpus californicus ) and dogfennel f Eupatorium capillifolium ) . Major changes in the littoral zone vegetation resulted from the drought. The overall species richness and total cover values within the wetland were within the range found in previous periods, but the manner in which the cover was apportioned over the various taxa was significantly different. For both the topsoiled and overburden areas, the cover of many common species declined and dramatic increases in cover were shown by other taxa, especially dogfennel and bulrush. Dogfennel increased profoundly in cover percentages (25 percent and 18 percent for muck treatment and overburden areas respectively) (Table 7) , especially in the deeper areas of the wetland as the water levels receded. At the peak of the drought, most of the area that typically had standing water was vegetated with a well established, monospecific stand of dogfennel by April of 1985. The timing of the dogfennel germination means that the seeds would have had to have been lying dormant in the substrate; as the water level receded,

PAGE 95

, .. . ; r • 87 Table 7. Percent cover of EUPatorima capillifoi Hn^ and Sgirpyg callfornlcua on muck treatment and overburden tranBecte, Fort Green marsh, eight sampling periods between fall 19t2 and summer 1985. Sampling Period EUDatorium caDilllfoliuM Scimus califomicua Muck Transects Overburden Muck Transects Overburden Fall 1982 6 Spring 1983 0.2 Summer 1983 0.4 0.1 Fall 1983 0.1 <0.1 Spring 1984 0.1 0.2 0.2 Summer 1984 0.3 0.2 0.2 0.3 Fall 1984 1 0.3 0.9 0.9 Summer 1985 25 18 6

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88 the dogfennel seedbank responded and a complete cover developed. Bulrush also increased in cover at the north end of the basin, as seen in 1985 results from transects 125, 130, and 139. As with dogfennel, the increase occurred in normally flooded areas lacking established emergent vegetation. The area of bulrush invasion was also a site of noticeable invasion by Saaittaria lancifolia and dogfennel. These areas showed little to no invasion by cattail, which was well established in the vicinity and had been spreading vegetatively for the previous two seasons. Bulrush was able to colonize and establish in an area that appeared to be ideal for cattail invasion. The transect specific elevation profiles and inundation frequencies were used to compare the zones of establishment of cattail and pickerelweed (Table 8) . The two taxa do occupy roughly the same zone within the wetland based on the patch establishment (Figures 15a through 15f ) , from approximately elevation 36.33 to 36.58 m msl and with an inundation range of 40 to 80 percent. The results from transect 105 are particularly interesting because the mulch was spread in deeper areas, down to elevation 35.51 m msl, that were permanently flooded. These deepwater stands were neither invaded nor encroached upon by cattail during the study period. They were also not ephemeral in nature, remaining constant throughout the study although they showing similar

PAGE 97

(M 01
PAGE 98

90 drought response. This indicates that macrophytes like pickerelweed can become established in deep water areas and muck application should be extended down to elevations with an average depth of flooding of up to 1 m or more. Large stands of pickerelweed developed only in the muck treatment areas. Though it produced large numbers of seeds, pickerelweed did not spread far from the areas of initial establishment during the first four growing seasons. Upland Succession Plots Seed Germination and Survival The experiment was originally designed as a nested analysis of variance with a balanced design (i.e., equal replications for each treatment) . A sampling mistake during the second weeding event (May) changed this plan, when plot 15 was weeded instead of plot 18. The error was not discovered until the third weeding (June) , at which time it was decided to continue weeding plot 15. This change created some difficulties as to the treatment status of plots 15 and 18. To incorporate plots 15 and 18 into the analysis, the analysis of variance (ANOVA) for each species was carried out using two different assignments for the plots: one analysis with plot 15 assigned to weeded treatment and plot 18 dropped and a second analysis with both plots dropped. Analyzing the data following the original plot assignments (15 to enhanced

PAGE 99

91 colonizer and 18 to weeded) was clearly inappropriate, as plot 15 could be no longer be considered as part of the enhanced colonizer treatment after it was weeded, but a simpler solution seemed to be to drop plots 15 and 18 from the statistical analysis altogether. Although an unbalanced design may result, any problems of equivocation over the treatment status of plots 15 and 18 are eliminated. An ANOVA configuration in which plot 15 is assigned to the weeded treatment and plot 18 is dropped is also a fairly clearcut case. As plot 15 was weeded during the later part of the growing season, the seedlings were growing under weeded conditions beyond the germination stage. The seed plots yielded information on germination, the survival of the germinating seeds, and the growth of the surviving seedlings. Total germination was estimated with data from the two sampling periods in March and October 1984 (Table 9) . Because the location of each seedling in the plot was recorded at the time of sampling, the fate of any given seedling could be followed through time. Thus, the mortality of germinating seedlings could be estimated and an idea developed of the phenology of germination (Table 10 and Figure 16) . Overall, 20 percent of the seeds planted did germinate and percent of those germlings survived through the first growing season. The individual species showed a full range of response in both germination and survival. Magnolia was

PAGE 100

§ O • 0 c o C 4J •H eO H C « a 4) u u « U 3 10 I a o 92 to (0 (0 p o 10 0 0) to 0) •H c •H T3 U (0 O C H c o •H •P (0 c g1 Q) 10 CP •o o 0) M 0) (0 to s i3 P •H . :» -p c CP 0) c a o -P (0 0) p -o c (0 to 4) •H 0 « to >1 Xi c >> •H 0> »4 « o p o o s 1

PAGE 101

O t) Ot « 2;:: « «W O "d o a 5 « •H ^ ^ W C C e «-H o P ^ g U O H m t. (0 iH 3 0) « »4 Q) 0) P P Id o ^ -o -o a (U c S c 0) 0) JS g T3 P "(DO T] ^ P C « fl 5 w •5 ^ O 0) <8 P >i-P
PAGE 102

u •O 00 u 5 o 4i o 5 5 a" (0 c •H u o cu 0) a Qi n c •H ® 0) "O >^ « C s 0 g to T3 o U> ft « C C n •H CO E2 0) o O iH 0)
PAGE 103

p«|iU|iiiJ«o tpVAt iO j«quinN •A|)W|nuino

PAGE 104

96 unique in that no seeds germinated regardless of plot or treatment. Sweetgum had only 6 percent germination and only 33 percent of those survived. Sugarberry had 19 percent germination, but only 30 percent survival. The other three taxa had much higher survival rates. Hickory had 10 percent germination with 75 percent survival. Germination in cabbage palm was 13 percent with 100 percent survival. Oak had both high germination (46 percent) and high survival (87 percent) . Because of the difficulty in accurately distinguishing between young laurel oak and young live oak seedlings, the two are treated as a single taxon. The species showed interesting combinations of germination phenology and survival. The majority of sugarberry and sweetgum germination occurred before the March sampling. Additional seeds germinated between March and October, but mortality in both cases was so high that the total number of live seedlings was lower in October than in March (see Figure 16). Germination of hickory and oak had germination occurred throughout the growing season, with a larger number of seeds germinating after March. For these two taxa, the germination phenology combined with low mortality resulted in a greater number of live seedlings at the second sampling period than the first. Finally, cabbage palm demonstrated a different germination pattern, with all germination occurring after March (see Figure 16) .

PAGE 105

97 Another way of analyzing the seed germination and survival data is to compare at the end of season survivors as a proportion of the seeds planted. The data on seedling survival from the experimental plots were converted to percentages for analysis. It is known from statistical theory that proportions or percentages have binomial rather than normal distributions, and that the deviation from normality is greatest for small and large values. The data can be transformed, however, to obtain a distribution that approximates normal. The square root of each percentage was transformed to its arcsine to give an underlying distribution that is nearly normal. The percentages were so transformed (Table 11) before conducting the ANOVA. For the case where the data are summed over species within each plot the results of two ANOVAs are similar (Table 11a) . When data from plots 15 and 18 are neglected in the analysis, the means for the weeded, natural colonizer, and enhanced legume treatments are not significantly different, but the enhanced colonizer treatment mean is lower and significantly different from the other three. When plot 18 is dropped and plot 15 is assigned to the weeded treatment the result is essentially the same. The plot-by-plot survival results can also be examined for individual species. The analysis assumes that there are no interactions between species. Because this assumption cannot be made for multi-species seed mixes any inferences

PAGE 106

98 Table 11. Comparison of mean percent germination/ survival for four experimental treatments (weeded, natural colonizers, legume, enhanced colonizers) using arcsine transformed data. Means compared following an ANOVA, using Duncan's multiple range test. Means with the same letter are not significantly different (p =.05). Table 11a. All species summed Treatment Means Plot Assignments PR>F Weeded Natural Enhanced for ANOVA (ANOVA) Legume Colonizers Plots 15 & 18 25.017 23.567 22.857 19.027 Neglected .0079 A A A B Plot 15 Weeded, 25.510 23.567 22.857 19.027 18 Neglected .0031 A A B B

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Table lib. Pignut hickory ( Carya glabra ) Treatment Means Plot Assignments PR>F Weeded Natural Enhanced for ANOVA (ANOVA) Legume Colonizers Plots 15 & 18 16.080 17.390 14.292 10.897 Neglected NS A A A A Plot 15 Weeded, 16.167 17.390 14.292 10.897 18 Neglected NS A A A A

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Table 11c. Sugarberry ( Celtis laevigata ) . Treatment Means Plot Assignments PR>F Weeded Natural Enhanced for ANOVA (ANOVA) Legume Colonizers Plots 15 & 18 17.693 8.892 12.420 5.847 Neglected .0772 A A A B B B Plot 15 Weeded, 18.387 8.892 12.420 5.847 18 Neglected .0297 A A B ET B

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Table lid. Sweetgum ( Liquidambar styracif lua ) 101 Treatment Means Plot Assignments PR>F Weeded Natural Enhanced for ANOVA (ANOVA) Legume Colonizers Plots 15 & 18 7.863 11.057 2.992 4.7 Neglected NS A A A A Plot 15 Weeded, 6.217 11.057 2.992 4.7 18 Neglected NS A A A A

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102 Table lie. Oak (Quercus) Treatment Means Plot Assignments PR>F Weeded Natural Enhanced for ANOVA (ANOVA) Legume Colonizers Plots 15 & 18 42.127 41.105 39.645 33.930 Neglected .0604 A A « A B Plot 15 Weeded, 42.127 41.105 39.645 33.930 18 Neglected .0347 AAA B

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Table llf . Cabbage palm ( Sabal palmetto ) . * 103 Treatment Means Plot Assignments PR>F Weeded Natural Enhanced for ANOVA (ANOVA) Legume Colonizers Plots 15 & 18 25.833 18. 155 10.410 11.910 Neglected .0841 A A B B B Plot 15 Weeded, 27.040 18. 155 10.410 11.910 18 Neglected .0300 A A B B B

PAGE 112

104 regarding the results will lack some degree of statistical rigor. In spite of this inability to meet all assumptions required by theory, the analysis by individual species may provide valuable insight to the hypotheses being tested that might otherwise be ignored. Therefore, an ANOVA was run on the transformed survival data for each species. Magnolia was not included in the analysis because none germinated in any plots. The results are again presented in two ways depending on how plots 15 and 18 were assigned. Hickory (Table lib) and sweetgum (Table lid) are the simplest cases; no significant differences were seen among any of the treatment means in either of the two ways plots 15 and 18 were assigned. Sugarberry (Table 11c) and oak (laurel oak and live oak summed) (Table lie) showed similar patterns in response to two different ANOVA situations and both had significant differences in at least some of the treatment means. When plots 15 and 18 were neglected, the two taxa exhibited slightly differing results. For sugarberry, the weeded, enhanced legume, and natural colonizer means were not significantly different, but weeded and enhanced colonizer means were. For oak, the weeded, natural colonizer and enhanced legume means were not significantly different from each other but were all different from the enhanced colonizer mean, which was also lower.

PAGE 113

105 In the second ANOVA configuration, in which plot 15 was assigned to the weeded treatment and plot 18 was ignored, sugarberry and oak showed similar but not identical patterns. The means were not significantly different for sugarberry for the weeded and enhanced legume treatments or among the legume, natural colonizer, and enhanced colonizer treatments. The weeded and enhanced means were different, with the enhanced colonizer value the lower. For oak, the weeded, natural colonizer, and enhanced legume treatment means were not different from each other and all were significantly different from and higher than the enhanced treatment mean. Cabbage palm exhibited significant differences between some treatment means, but the results were the same for both ANOVA configurations (Table llf ) . The means for the weeded and natural colonizer treatments were not significantly different, and the natural colonizer, enhanced colonizer, and enhanced legume means were not significantly different, but the weeded mean was different from and higher than the legume mean. ^ i > ^ , Height Growth in Seed Plots .5 Height growth data from the seed plots were analyzed in the same manner as the survival data for each individual species and for the sum of all species (Table 12) . When the height data were summed over species, the ANOVA results were the same in both combinations of assigning plots 15 and 18

PAGE 114

106 Table 12. Comparison of mean seedling height growth (cm) for four experimental treatments (weeded, natural colonizers, legume, enhanced colonizers) . Means compare following an ANOVA, using Duncan's multiple range test. Means with the same letter are not significantly different (p <.05). Table 12a. All species summed Treatment Means Plot Assignments PR>F Weeded Natural Enhanced for ANOVA (ANOVA) Legume Colonizers Plots 15 & 18 7.78 6.4 6.26 5.8 Neglected .0001 A B B B Plot 15 Weeded, 8.02 6.4 6.26 5.8 18 Neglected .0001 A B B B

PAGE 115

^^ J « I y. 7, Table 12b. Pignut hickory (Carya glabra) 107 Plot Assignments PR>F for ANOVA (ANOVA) Treatment Means Weeded Natural Enhanced Legume Colonizers Plots 15 & 18 Neglected NS 6.25 5.61 5.61 5.17 A A A A Plot 15 Weeded, 18 Neglected NS 5.87 5.61 5.61 5. 17

PAGE 116

108 Table 12c. Sugarberry (Celtis laevigata). , -^J Treatment Means Plot Assignments PR>F Weeded Natural Enhanced for ANOVA (ANOVA) Legume Colonizers Plots 15& 18 8.5 7.0 6.5 8.0 Neglected NS A A A A Plot 15 Weeded, 8.3 7.0 6.5 8.0 18 Neglected NS A A A A

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Table 12d. Sweetgum ( Liquidambar styracif lua ) Treatment Means Plot Assignments PR>F Weeded Natural Enhanced for ANOVA (ANOVA) Legume Colonizers Plots 15&18 6.0 5.0 4.0 4.5 Neglected NS A U K A Plot 15 Weeded, 6.0 5.0 4.0 4.5 18 Neglected NS A A A A

PAGE 118

110 Table 12e. Ouercus . Treatment Means Plot Assignments PR>F Weeded Natural Enhanced for ANOVA (ANOVA) Legume Colonizers Plots 15 & 18 7.81 6.26 6.19 5.63 Neglected .0011 A B B' B Plot 15 Weeded, 8.17 6.26 6.19 5.63 18 Neglected .0001 A B B B

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Ill Table 12 f. Cabbage palm (Sabal palmetto) Treatment Means Plots 15 & 18 8.14 8.65 7.09 7.67 Neglected NS A A A A Plot 15 Weeded, 8.23 8.65 7.09 7.67 18 Neglected NS A A A A

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112 (Table 12a). In both cases, the F-value was significant (p =.0001) and the mean height growth for the weeded treatment was significantly different and higher than the other three treatment means. There were no significant differences among the means for the natural colonizer, enhanced legume, and enhanced colonizer treatments. Assigning the height growth data by individual species reveals an interesting trend. Generally, the oak results mimicked the results from the combined species data, while hickory, sugarberry, sweetgum, cabbage palm, and magnolia all had similar results as a group that were quite different from oak. As in the case with height data summed over species, the oak data had a highly significant F-value for both ANOVA regimes. The weeded treatment mean was found to be significantly different from and higher than the other three treatment means, which were not significantly different from each other (Table 12e) . For the most part, the growth response of the other four species (hickory, sugarberry, sweetgum, and cabbage palm) were similar. In all cases, no statistically significant differences were seen among the treatment means (Tables 12b, 12c, 12d, and 12f ) . Height Growth in Transp lant Plots The three species (sweetgum, live oak, and cabbage palm) were first treated separately in the analysis under the assumption that the 1-m spacing between seedlings would

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prevent any interaction between species. Analysis was also performed summing growth data for all three species together. The ANOVA of the height growth data for each of the three species showed a significant F value (p < .05) (Table 13), indicating that at least one of the treatment means was significantly different from the rest. Duncan's multiple range test was used to determine which treatment means were significantly different (Table 13) . For sweetgum seedlings, the mean height growth for the weeded treatment was significantly different and higher than the mean height growth of the other three treatments, and there was no significant difference among the means for the natural colonize, enhanced colonizer, and enhanced legume treatments. The mean height change for the live oak seedlings was also significantly different for the weeded treatment. The live oak seedlings in the weeded plots had a higher mean growth change over the first growing season. The analysis again showed no significant difference among means in the other three treatments. The Duncan's multiple range test for the cabbage palm data yielded different results. Weeded, enhanced legume, and natural colonizer treatments were not significantly different from each other and neither were the natural and enhanced colonizer treatments. The weeded and legume treatment means

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114 were both significantly different from and higher than the enhanced treatment mean. When growth data were summed over species, the results were the same as for sweetgum and live oak. The mean for the weeded treatment was significantly different and higher than the means for the other three treatments, which were not significantly different from each other. Mound-Building Ants Mound Survey The field surveys showed mound densities of 560/ha, 2,070/ha, and 2,100/ha for the 1-, 2-, and 5-year old sites, respectively. Average mound volumes were 600 cm^, 2,42 0 cm^, and 1,250 cm' for the 1-, 2-, and 5-year old sites, respectively. Plant Growth Study The results of the vasey grass growth test (Table 14) show a uniform trend of significantly different and higher growth rates for the plants grown on mound soil for all three sites. A statistically significant growth enhancement was found in all three cases for the aboveground, belowground, and total plant biomass. For all comparisons, the mean biomass value for the mound samples was higher and significantly different (p < .01) .

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115 Table 14. Results of vasey grass growth bioassay on mound and non-mound soils from 1-, 2-, and 5-year old sites. Site ( aae) Seedling Growth Parameter Mean Mound ii^ W X X Non-mound OvJX J. P Tiger Bay (1 year) Below ground biomass (g) 0 . 242 0 139 Above oround biomass (g) 0 386 U • X o ^ n n n K Total biomass (g) 0.626 0. 301 . 0006 Fort Green (2 year) Below ground biomass (g) 0.233 0. 145 . 0003 Above ground biomass (g) 0.226 0. 153 .004 iotai Diomass (g) 0.459 0 • 298 . 0004 Clearsprings (5 year) Below ground biomass (g) 0.284 0.172 . 0001 Above ground biomass (g) 0.308 0. 160 .0003 Total biomass (g) 0.592 0.332 .0001

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116 The sweetgum growth bioassay also showed a uniform growth enhancement on the mound soil (Table 15) . For all growth parameters measured (stem biomass, root biomass, leaf biomass, total biomass, leaf area, and stem height), the mean for the mound soil was significantly different (P < .05) and higher than the non-mound mean. For biomass and leaf area growth parameters, the means for the seedlings grown on the three mound soils were at least twice those of the seedlings on the non-mound soils. Chemical Soil Analyses Chemical analysis of mound and non-mound soils highlights some differences in several of the chemical parameters assayed. Because the sampling technique used was paired samples, results are presented as mean differences of each pair with the non-mound value subtracted from the mound value (Table 16) . Positive differences connote higher values for the mound samples. pH values exhibited a wide range at each of the three sites but tended to be circumneutral as compared to the characteristically acid soils native to the region. The mean difference of pH values between pairs was not statistically different at any of the three sites. Calcium levels showed no statistically significant differences between sample pairs from any of the three sites. For magnesium and manganese, no statistically significant

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117 Table 15. Results of sweetgum growth bioassay on mound and non-mound soil from 1-year old site. Seedling Growth Parameter Mean for mound soil (n=5) Mean for non-mound soil (n=6) P Stem biomass (g) 0.41 0. 14 .0001 Root biomass (g) 0.99 0.42 .0002 Leaf biomass (g) 0.34 0.17 .0003 Total biomass (g) 1.73 0.67 .0001 Leaf area (cm^) 89.68 44.30 . 0003 Stem height (cm) 13.4 9.68 <.03

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118 Table 16. Results of paired-difference comparisons between mound and non-mound soils for selected chemical parameters from Tiger Bay (1 year-old). Fort Green (2 year-old) and Clearsprings (5 year-old) reclamation areas. Difference (Moiind Non-mound) Site Age ( xeaiTS ) Mean Error Range p Calciun 1 315.0 227.4 250 to 1250 NS (mg/k) 2 -198.5 343.5 -1370 to 970 NS 5 -93.3 366.7 -510 to 340 NS Magnesium 1 108.3 121.8 -90 to 700 NS (mg/lc) 2 -38.3 51.6 -260 to 90 NS 5 48.3 15.1 -10 to 100 .05 Manganese 1 1.2 0.79 0.0 to 5.0 NS (mg/Jc) 2 0.0 0.26 1.0 to 1.0 NS 5 2.S 0.5 2.0 to 5.0 .01 Potassium 1 94.2 25.3 37 to 206 .05 (mg/k) 2 55.5 9.9 29 to 86 .01 5 79.3 14.5 52 to 141 .01 Sodium 1 28.3 10.7 8 to 72 .01 (mg/k) 2 24.8 9.3 4 to 54 .01 5 7.0 2.0 0 to 14 .05 Nitrogen 1 1902 288 1260 to 3220 .01 (mg/k) 2 764 188 350 to 1575 .01 5 1843 378 210 to 2730 .01 Organic 1 0.51 0.18 .06 to 1. 37 .05 Matter 2 0.27 0.15 -.39 to 0. 65 .2 (%) 5 0.15 0.09 -.13 to 0. 52 .2 PH 1 0.73 1.212 .26 to 1. 56 NS 2 -0.33 1.326 -.93 to 0 .56 NS 5 0.11 0.561 -.21 to 1 .12 NS

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119 differences were seen between sample pairs for the 1-year old and the 2-year old sites, but a significant positive difference was reported for the 5-year old Clearsprings site. Magnesium values were an average of 48.3 g/kg higher in mound soils than in non-mound soils. Manganese values were 2.5 g/kg higher in the mound soils. Potassium and sodium each had a statistically significant and positive difference at each of the three sites. For potassium, the mean difference was 94.5 g/kg for the 1-year Tiger Bay site, 55.5 g/kg for the 2-year site, and 79.3 g/kg for the 5-year site. The mean difference for sodium was 28.3 g/kg for 1-year site, 24.8 g/kg for 2-year site and 7.0 g/kg for 5-year site. Nitrogen values followed the same pattern as potassium and sodium with statistically significant (P < .01) positive differences at all three sites. Mean differences for the mound and non-mound soils were 1,902, 764, and 1,843 g/kg for the 1-, 2-, and 5-year sites, respectively. Tiger Bay mound samples had a range of nitrogen levels from 2,429 to 4,039 g/kg as compared to 539 to 2,709 g/kg for the non-mound soils. At the 2-year old Fort Green site, the ranges were 2,450 to 3,325 g/kg and 1,995 to 2,870 g/kg for the mound and non-mound samples, respectively. For the 5-year old Clearsprings site, the ranges were 3,899 to 6,699 g/kg for the mound soils and 1,869 to 5,089 g/kg for the non-mound soils.

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120 The organic matter analysis was less determinate but indicated some of the same trends. At the 1-year old Tiger Bay site, the mean difference for soil organic matter was significantly different (P < 0.5) and positive. Positive differences were also shown for 2-year old Fort Green site (27 percent) and the 5-year old Clearsprings site (15 percent), but these differences were only significant at marginal levels (P < .20) Physical Soil Analyses Bulk density . Bulk density measurements (Table 17) on soils from the one site that was sampled, the 2 -year old Fort Green site, showed a statistically significant difference between the means for the mound and non-mound samples. The mean bulk density of the mound samples was 1.19 g/cm^, compared to 1.74 g/cm' for the non-mound samples. Mound volumes can be calculated from circumference and height measurements, assuming a conical mound shape. Volumes range from 50 to 2850 cm'. Based on a average bulk density of 1.2 g/cm', a mound of average volume (approximately 1250 cm'^ has a soil mass of approximately 1,500 g. * » ' Infiltration Tests . Results of the three water infiltration tests at the Fort Green site (Table 18) showed the infiltration rate on mound soils to be considerably higher than on the adjacent non-mound soils. Mound soil infiltration

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121 rates were 5, 17, and 120 times higher than rates on the adjacent non-mound soils for tests 1, 2, and 3, respectively. Mound soils had infiltration rates of 0.1 to 6.0 cm/min versus 0.02 to 0.05 for the non-mound soils.

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122 Table 17. Results of bulk density analysis of mound and non-mound soils from 2-year old site (n=7) . Standard Mean Error Range P Mound 1.19 g/cm' 0.0735 1.00 to 1.43 .05 Non-mound 1.74 g/cm' 0.0473 ^ 1.66 to 1.99

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123 p (0 c o •H •p ta u p B s e o o o lO H 1-1 n (0 (0 ^ rH 0^ Id 2 B T3 T3 -0 C C C c 3 3 3 3 0 0 0 0 -a B e T3 6 T3 e c 1 1 c 1 C 3 c c 3 C 3 c 0 0 0 0 0 0 o s z X z H CN M =»»: p •p CO to U Q) 0) Eh b*

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DISCUSSION Marsh Development Seed Bank Formation The formation of a seed bank appears to be a relatively rapid process, beginning almost immediately after the land surface has been exposed. Seed bank samples from all but the youngest mine sites fall within or just below the range of seed density and species diversity found in natural wetlands in Florida, Iowa, and New Jersey. The species present in the seed bank samples are largely the wetland ruderal species characteristic of environments subject to disturbances such as water level fluctuations. They are the initial colonizing species, the annuals and short-lived perennials of exposed mudflats, wetland transition zones, and shallow littoral zones. Notably absent are the late successional marsh species: the emergent macrophytes, submergent macrophytes, and free-floating aquatic species. A possible reason is the germination conditions used in the seed bank tests, which were similar to those of an exposed mudflat, but the absence of the seeds of the late successional species from the samples is a more likely cause. The seeds 124

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125 and fruiting bodies of many macrophytes (pickerelweed, water hyacinth, cow-lily ( Nuphar luteum ) , white water-lily ( Nymphaea odorata) , Saaittaria . and Peltandra virqinica are large enough to be easily seen, and no large seeds were observed in any of the samples. The question arises of how pickerelweed, Saaittaria . cowlily, and white water-lily could be present in at least a few of the wetlands sampled, if none of their seeds were detected in this assay. It may be beneficial to discuss the species present in the seed bank samples versus those conspicuous by their absence in terms of successional status and life history characteristics of the adult, established phase and juvenile, regenerative phase. Regenerative strategies may be related to successional status. Formation of a persistent seed bank represents only one of three regenerative strategies used by wetland plants; the others are vegetative expansion and production of numerous wind-dispersed seeds. Generally, vegetative expansion, is successful where the adult plant is already established. Most long-lived macrophytes are capable of vegetative expansion which allows for rapid colonization of open space, such as small patch disturbances within a large existing stand of marsh vegetation. In habitats characterized by chronic but unpredictable disturbance (fire, flood, or drought) , where vegetative structure is destroyed over large areas, the persistent seed bank is typically the primary regenerative

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126 mechanism. The third regenerative strategy employed by wetland plants, the production of numerous wind-dispersed seeds, is useful in colonizing near and distant open areas, especially those that lack a seed bank. Many species employ more than one strategy. Seeds of most wind-dispersed species remain viable at least for short periods of time in a seed bank. Cattail uses all three regenerative strategies; it is capable of rapid vegetative growth and produces prodigious amounts of wind-dispersed seeds, which are also capable of lying dormant in a seed bank. The perennial macrophytes present within the wetland zones sampled may rely on vegetative expansion as their primary regenerative strategy. Alternatively, their seeds may have been present but in relatively scarce amounts or a patchy distribution. As noted earlier, all root and rhizome material was removed from the samples. In hindsight, it would have been instructive to retain the root/rhizome material and check for sprouting. Even for species that use vegetative expansion as the primary regenerative strategy, the production of viable seed represents an essential component of the total regenerative strategy . , . r, , . . . Formation and St abilitv of Macrophvte Communities In regard to the pattern of succession observed at the Fort Green marsh, the vegetation dynamics described in this

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127 study show that the plant communities that developed in the two treatment areas differed in species composition and that these differences remained stable through at least the first four growing seasons. This stability suggests that initially established vegetation can occupy the available open space and resist invasion or encroachment by other taxa. Dense stands of pickerelweed established in the muck treatment areas remained stable and were not invaded by cattail, primrose willow, or other aggressive weedy species typically associated with arrested succession on unreclaimed phosphate-mined lands. Similarly, dense stands of cattail have also remained stable, resisting invasion. In contrast, open stands of cattail in other portions of the wetland were invaded by bulrush in 1984 and 1985. Recent studies show that dense stands of bulrush have since developed in these areas, competitively displacing the cattail (G.R. Best, personal communication, 1988) . Bulrush showed an ability for widespread dispersal of waterborne seeds, colonization, and rapid vegetative expansion. The marsh transect studies indicated that the initial floristic composition, sensu Egler, largely determined the species composition within the marsh, and that in the absence of disturbance, the initial vegetation pattern and species composition are maintained for some time, possibly even long-

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128 Patch dynamics . The use of permanent transects allowed the fate of individual patches to be tracked through time. The large stands of cattail and pickerelweed developed from individual plants or patches that gradually coalesced into larger units. A similar pattern of plant establishment can occur on abandoned coal-mined land, as patches or islands that grew individually and eventually coalesced (Game et al., 1982) . Some patches disappear and are replaced by an individual or group of individuals of another species. This suggests that a patch has to be of some critical size before it can be successfully established, and that the "critical" patch size probably changes as a function of the surrounding vegetation and the growth rate of the species. The vegetation pattern composition and species composition of a marsh community appear to be largely a function of the propagules available and the prevailing environmental conditions which supports the seed bank/ environmental filter model described by van der Valk (1981) . The community responds to an array of environmental factors that affect its composition. Major environmental factors affecting wetland communities include depth, duration, and seasonal pattern of flooding, and fire. Effect of Herbivory. Herbivory can also be an important factor regulating species composition and productivity in wetlands. Feral hogs are common in the Payne Creek floodplain

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129 and create patch disturbances of varying size within the wetland. The affected areas are typically disturbed down to the subsoil, with all vegetation removed. The hog activity observed during the marsh study was generally restricted to the wetland/upland transition zone. Bersok (1986) found the impact of the foraging hogs in this marsh was limited to monospecific stands of cattail, and patches opened by hogs were recolonized by vegetative expansion of the surrounding cattail plants. This type of disturbance may be similar, although less extensive, to the muskrat "eatouts" described by van der Valk and Davis (1976) and Weller (1981) in marshes in the midwest. The effect is to create a shifting mosaic of open areas available for colonization. Effect of Hvdroperiod and Drought . The hydroperiod factors of depth, duration and seasonal pattern of flooding have a broader impact than hog activity on the marsh. The water level fluctuations provide a seasonal dynamic. Of more importance though are the events with periods longer than a year, such as the regional drought cycle that occurred from fall 1984 through summer 1985. As the drought cycle is a natural part of the climatic regime, it is one to which a wetland must be adapted. The reaction to the 1984-85 drought showed that the marsh had developed a mechanism to respond to environmental change.* Drought conditions exposed previously flooded but unvegetated

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130 areas that were colonized subsequently and rapidly by a variety of species. The timing of the drought and the species composition on the exposed flats demonstrated that the source of the colonizing species was the seed bank. The wetland had developed its own seed bank, which is one of the principal response mechanisms of wetlands to wide fluctuations in water level . Mature wetland systems respond to change with an in situ mechanism that includes the seedbank as a major component. In a short period, the Fort Green wetland has developed its own seed bank. The muck applied in 1982 provided an instant seed bank to certain areas, but the vegetation dynamics highlighted during the drought occurred in areas where no muck had been applied. Even on the muck treatment transects (97, 105, and 139) the rise of dogfennel and bulrush was confined to those portions that had not received the muck treatment. The establishment of bulrush and Saqittaria on droughtexposed flats at the north end of the site is particularly interesting, as the propagule source was undoubtedly from within the wetland itself, and highlights the autogenic aspect of community development in seedbank formation. Bulrush and Saqittaria were planted; initially established plants spread vegetatively, produced seed, and now act as seed sources for further colonization. The formation of an internally generated seed bank may be one indicator of ecosystem maturity.

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131 Monitoring the fate of the drought-stressed or droughtkilled macrophyte communities will provide some additional insight into community dynamics in future years. Major patches of cattail and pickerelweed senesced in response to the drought (Figures 15a through 15f ) . Only time will indicate whether the whole plant was killed or only the aboveground portions. If the latter is the case, then the drought may have only hastened the annual fall senescence, as the aboveground portions of both taxa annually die back and the plants overwinter as leafless rhizomes. Even if large patches were killed by the drought, species replacement may be slowed or inhibited by the presence of standing dead plant tissue; since as these studies have shown, an occupied space is difficult to colonize. The marsh transect study does not and cannot address the long-term stability of created marsh communities like the Fort Green site. There is no reason to believe that the marsh system will not eventually develop into a forested wetland. Tree seedlings planted within the wetland have done quite well through the first four growing seasons (Best and Erwin, 1984; Erwin et al., 1985). The mature marsh system may actually be an immature swamp system.

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Wetland Succession Model 132 Role of Life History Characteristics Regenerative strategies and other life history characteristics are the foundation of van der Valk's wetland succession model. The plant community's response to climatic cycles of flood and drought and changing environmental conditions is analyzed through the life history characteristics of the species residing in the seed bank. The environmental factors in the model act as a "sieve" and screen species from the seed bank. The life history characteristics considered in the model include: propagule longevity (short-lived dispersing or long-lived seed bank forming) , life span of the established plant (annual or perennial) , and propagule establishment requirements (germination under drawdown or flooded conditions) . The model has generally been applied to succession in marsh systems, but would seem to be equally appropriate for forested wetlands. The addition of woody species could be easily accomplished by incorporating the appropriate life history characteristics for propagule longevity, propagule establishment requirements, and life span of the established plant. Importance of Allogenic and Autogenic Factors | ' The van der Valk model is useful in describing some aspects of wetland succession and showing the importance of

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133 allogenic forces (the environmental sieve) on the wetland vegetation. The model emphasizes, as did Gleason and others (Drury and Nisbet, 1973; White, 1979), that the key to vegetation dynamics lies in understanding the life history characteristics of the species constituting the vegetation. This suggests that succession can be explained entirely as a disintegrated individualistic phenomenon. A conceptual model with a focus limited to allogenic factors and the life history strategies of the individual species ignores many of the biological properties of the wetland community. The model's focus on secondary succession assumes that the community structure is already in place and does not account for the processes that build that structure. The model does not explicitly recognize the autogenic processes and, therefore, lacks the feedback to show how the environmental sieve can itself be modified to some extent by the wetland vegetation. An example of autogenic feedback is the formation of an organic soil through peat deposition. Wetland succession can occur on mineral soil, depending on the site conditions and the nature of the disturbance that initiated the succession. Certainly, in the case of unreclaimed mined land, the wetland community will develop on mineral substrate. Through time, an organic substrate accumulates as litterfall exceeds decomposition. The accumulated organic sediments raise the effective ground level in the wetland, thus altering the

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134 effects of changes in depth frequency and duration of flooding. The organic sediments also provide a rooting medium, seed storage medium, and microfaunal habitat that is quite different from the underlying mineral substrate. The model fails to recognize that wetlands tend to change with time from "young" to "older," more mature stages (Mitch and Gosseklink, 1986) . Young stages after establishment are characterized by (1) plant species that are opportunistic, early colonizers capable of being established from seed and growing in a variety of different habitats, (2) soils that are typically mineral in nature with low organic matter content, and (3) subsurface hydrology and chemistry controlled by the mineral soil. As the system ages, it becomes more "mature": (1) the plant community may become dominated by species more characteristic of mature wetland systems, (2) the wetland soils may gradually change and gain an increasing amount of organic matter, and (3) the subsurface hydrology and chemistry may change in response to the changes in wetland soils. Maturation is to a large extent the action of the autogenic processes within the wetland. The accumulation of sediments and the formation of an organic soil is due to litter production, decomposition, and the depth and duration of flooding. By building the soil structure, the biological community provides a feedback to the environmental sieve and modifies its effects. The mature community has a greater degree of internal control than the young community.

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135 Another example of the process is found with cypress domes which may influence the shape and depth of their own basins through the production of acid waters, that percolate down and cause solution of the underlying limestone (Odum, 1984) . Also, the sawgrass marshes of the Florida Everglades are fireadapted communities whose continued survival depends upon fire (Wade et al., 1980). The sawgrass plants accumulate fuel in the form of standing-dead leaf litter, and when sufficient litter has accumulated and conditions are right, a fire may occur. Fire is an allogenic process, but the timing, frequency, and severity of the fire are influenced by the growth characteristics of the sawgrass. Another excellent example of this kind of feedback loop is discussed by Weller (1981) . In midwestern prairie pothole marshes, the vegetation is periodically destroyed by muskrats. New emergent vegetation cannot become established until a dry year exposes the substrate. A typical succession follows until cattails out-compete the other plant species. This sets the stage for another muskrat population explosion. The cycle has a 6to 8-year frequency that depends on both the biotic vegetation-muskrat interaction and the abiotic water levelclimate cycle. , Eclectic Wetland Succession Paradigm Evidence supports the conclusion that both allogenic and autogenic forces act to change wetland vegetation. A paradigm

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136 or conceptual model of wetland succession must recognize both these forces and the interplay or feedback between them. An alternative formulation of the van der Valk model (Figure 16) can be developed to include other system components, such as the wetland substrate and consumers, and to show the feedback relationships between the components and the environmental sieve. With regard to the competing paradigms (initial floristics, inhibition, relay floristics, coevolution, and self-organization) , this work and other studies indicate that all are operating at some time during wetland succession. The formation of plant communities from seed/propagule banks following disturbance is a case of initial floristics. Bersok (1986) found no significant difference between tree seedling success in cleared plots versus cattail plots. Pickerelweed and cattail stands that remain stable in the absence of disturbance and support to the inhibition model. Coevolution and relay floristics are important in wetland tree dispersal; bird and mammal species involved in seed dispersal must have their habitat requirements satisfied before they will use the site. Seed/propagule banks and accumulated belowground structures (e.g., roots, rhizomes) provide a storage of "choices" for all environmental contingencies, thus supporting the self-organization model.

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rH C Q) -H Q ^ C o •H (0 (0 0) o u 3 (0 •o c (0 •p 3 0) (0 to 0) 0) u tr 0 •H 0) C 0) 0) to o Q) > 0) ~*
  • ^ s "'•^ O -H g £ 4J +J (0 TJ "J •H 0) •o ;o 73 O to to to 0) 0) c u t^ H 0) •H -H Q) C H >i <4-l •H T! O 6 C o to •H a o

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    139 Upland Forest Plots Seed Germination and Survival The germination results and accompanying survival rates for the seed highlight several points. First, germination rates between species differ widely under field conditions, as shown by the two extremes of magnolia with no seeds germinating and oaks with nearly 100 percent germination. Germination was low for hickory, sugarberry, sweetgum and cabbage palm. Factors apparently affecting germination success include seed quality, site condition, seed predation, and seed size. The survival of individuals that germinated exhibited interesting species-specific trends that appear related to seed size and seedling adaptations. Effect of Seed Quality . Sugarberry, sweetgum, hickory, cabbage palm, and magnolia seeds had been collected a year before the study and stored dry at 4°C; oak acorns were collected the month before planting and stored outside in potting soil. The storage regime, as well as the initial quality of the seed, could have had an effect on germination potential. Many of the acorns were nearly germinating when planted. Also, because germination was determined only from the two sampling periods in March and October, any seeds that germinated but survived only a short time for would have been overlooked. This factor would have been more critical for

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    140 sugarberry and sweetgum, since these species produce a rather delicate seedling. Effect of site conditions . Seeds respond to environmental cues to germinate. In some cases, dormancy must be overcome. It is possible that the conditions in the field plots were more generally suited for some species than others. Effect of seed predation . Losses of seed and young seedlings could also bias the germination results. Seed losses to birds and small mammals are always a danger to any direct-seeding operation and are one of the primary causes of low germination in natural conditions, but for large-seeded species, this is also a necessary cost of dispersal. Freshly disturbed soil often attracts animals that consume seeds as part of their diet. Armadillos were observed on the study plots and raccoons, field mice, and feral hogs were also present in the reclamation area. Two factors were observed to lower the germination potential of hickory, one physical and the other biological. The hickory nut is very large and was easily winnowed out of the soil during heavy rain. This process may have been aided by the removal of hickory nuts by armadillos. Tracks and signs of soil disturbance in the plots by these animals were seen on several occasions, and the signs were usually associated with the presence of only the outer husks of the hickory nut.

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    141 No other seed predators were ever in evidence, although the freshly disturbed and seeded plots could have attracted birds and small mammals alike. Seed loss from predation is a process occurring regularly in natural systems. Effect of Seed Size . The germination and survival data (see Tables 9 and 10) highlighted some differences concerning seed size and seedling growth form. The species used in the seed plots fall into three categories based on seed size. Sweetgum has a small winged seed adapted for wind dispersal, and the small seed contains little food to nourish a young seedling after germination. Both sugarberry and cabbage palm have intermediate-sized seeds. The seeds have a fleshy exocarp to attract birds and mammals as dispersal agents, and both have modified cotyledons for food storage. Hickory, laurel oak, and live oak produce large, heavy seeds that obviously do not disperse far on their own. These species are highly dependent on animals for that function. Acorns and hickory nuts have large, starchy cotyledons that provide nourishment to the developing seedling, as well as to potential seed predators. The relationship between the food reserve of modified cotyledons and the survival rate of a germinated seed is striking. The large-seeded species had high rates of survival; 75 percent of all germinating hickories and 87 percent of all oaks survived. In contrast, only 33 percent of the sweetgum individuals survived the first growing season.

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    142 In the intermediate seed-size group, sugarberry had low survival while cabbage palm had the highest possible survival. The cabbage palm results may be anomalous, both because of the phenology of this species and the sampling schedule. During the first sampling period in March, no cabbage palm seedlings were present on any of the plots. All cabbage palm seedlings present in the October census had germinated between late spring and summer. Under this schedule cabbage palm seedlings had 100 percent survival. This could be misleading, because the cabbage palm seedling has a single, short, very leathery leaf, that resists decay for some time, even if dead. If cabbage palm seeds had germinated and the seedling later succumbed, the leaf could have remained long enough to be counted in the survey. Because there is no evidence to support this possibility, it is assumed that there may have been some slight mortality, but that survival rates for cabbage palm were high. The relatively superior performance of large-seeded species in direct-seeding trials has been noted in other studies. Toumey and Korstian (1942) noted that seeds containing a large amount of reserve food and germinating in early spring are better adapted for direct seeding than small seeds that are slow to germinate and produce plants of slow juvenile growth. Tackett and Grimes (1983) seeded three large-seeded species ( Ouercus rubra . Q. palustris . and Q. macrocarpa) with two small-seeded species (Paulownia tomentosa

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    and Alnus glutinosa) and found that after 5 years, a greater number of oak seedlings were established than seedlings of the small-seeded species. Seedling Adaptations to Drought Stress , Seedling growth form can be especially important in determining the fate of germinating seeds. Along with its tough, leathery leaf, the cabbage palm seedling possesses a thick, leathery root system and is well adapted to handling drought stress. The aboveground and belowground tissues are strong enough not to collapse under moisture tension. Conversely , the sugarberry seedling has a delicate stem and root that are more rapidly affected by moisture stress. It is thus reasonable to assume that sugarberry mortality would be higher than that of cabbage palm if dessication were a problem, as is the case on exposed, unvegetated, overburden soils. This analysis of seedling anatomy can be extended to the other taxa in the study. Sweetgum, like sugarberry, produces a seedling with delicate shoot and root and would be expected to be killed more easily by drought stress. Hickory and oak both produce a stout woody shoot and a tough fibrous root system that makes them better adapted for coping with water stress. The survival data for all species summed together showed that the enhanced colonizer treatment had the lowest values. Several factors may have influenced this outcome. Competition

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    144 among tree seedlings and herbaceous plants may have been more intense in the enhanced treatment plots, thus reducing survival and possibly germination. Allelopathic inhibition of either growth or germination of woody plants by the species added is also possible. One of the enhanced colonizers, Andropogon virqinicus . has been reputed to produce allelochemicals that inhibit the growth of other plant species (Rice, 1978) . Effect of Erosion . When the major erosion problems began in early January 1984, the extent and degree of erosion on site were assessed and mapped. An examination of the map and field notes from this time show that eight seed plots were affected by erosion rills. By chance, the affected plots were evenly distributed among the four treatments. Several plots affected by erosion exhibited low survival and others showed high values. Only in two cases were seeds observed to have been washed out of plots (numbers 12 and 13) and these were replaced by hand. However, this does not preclude the possibility of some seeds having been lost completely from some plots or washed from one plot into a down-slope plot. One indication that there was no significant movement of seed between plots is that no individuals of any of the planted legume species were ever found in plots other than the ones in which they were placed. The germination and survival results for the individual species were varied and less clear in support of one of the

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    145 three models. Hickory and sweetgum exhibited no significant differences in survival under any of the four treatments, which provides support for the initial floristics model. The results may be influenced by the generally very low survival values, as some plots had only a single individual or none at all. Germination and survival results for sugarberry do not clearly favor any of the three models, and also may have been affected by generally low numbers of seeds germinating and surviving (less than 6 percent overall). Cabbage palm germination results appear to reject the relay floristics model but do not clearly favor either initial floristics or inhibition. The weeded mean was higher than the means for the two enhanced colonizer treatments (legumes and old-field weeds) , but the mean was not different from the colonized treatment where the treatment seeds were added naturally. The results for oak also do not clearly support any of the three models, although there is some support for rejecting the relay floristics model. The weeded, natural colonizer, and enhanced legume means were significantly different from and higher than the enhanced colonizer mean, but the three means were not different from each other. Once again, the enhanced treatment came out lowest, raising the guestion of whether competition, allelopathy, or another form of inhibition was involved because of the species added in this

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    146 treatment. The means for the other three treatments were not significantly different. The oak results may be similar to those of hickory, suggesting a causal relationship between large food reserves in the seed and less treatment-related mortality in the first growing season. Height Growth Seed plots . When seedling height data are summed for all species, significantly different and greater height growth appear to be a result of the weeding treatment. This result seems clearcut and profound, as seedlings in the multi-species plots grew significantly better under the weeding treatment, and relay floristics and initial floristics models must therefore be rejected in favor of the inhibition model. Closer examination, however, indicates the results may actually support more than one model. When the growth data are summed over all species, the resultant data set is heavily biased toward the oak; both because the two oak species were combined to avoid skewing results from misidentif ication of individual seedlings and because oak had a higher level of germination and survival than the other taxa. Oak seedlings made up 74 percent of all seedlings found, whereas cabbage palm comprised 12 percent, hickory 7 percent, and sugarberry and sweetgum 5 and 2 percent, respectively. It is therefore not surprising that the height growth analysis for oak has exactly the same

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    147 results as the analysis for all species summed. The vastly greater number of oak seedlings masks the responses of the other species, which, if examined separately or at least apart from the oak data, lead to a much different conclusion. The results of the height growth analysis for the other four species are surprisingly uniform and contradictory to the oak results. The ANOVAs for each show no significant differences in mean seedling height among any of the four treatment means, which supports rejection of the relay floristics and inhibition models in favor of the initial floristics model. This may indicate that individual species do not show the same response. In addition, the erosion problems encountered early in the study provide support for the relay floristics model, by showing that the early colonizing plants help stabilize soil. Transplant plots . The transplant plot seedling growth data can be considered to provide either clarity or more confusion. Unlike the seed plot data, the transplant plots did not have differing interpretations depending on whether species were combined or treated separately. The result were the same for three cases and barely dissimilar for the fourth case. For sweetgum, oak, and all species combined only the weeded treatment was shown to be significantly different and it had the highest height growth. For cabbage palm, the mean seedling growth in the weeded treatment was not clearly

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    148 superior but it was, along with the natural colonizer treatment, significantly different from and higher than the enhanced legume treatment mean. Comparisons between seed and transplant plots . The seedling height growth results from the seed and seedling plots provide two views of the interaction between laterarriving tree species and colonizing plants. Because the three species used in the seedling transplant plots were also in the seed plots, a valuable means of comparison was provided. The oak seedlings exhibited the same height growth response under experimental treatments in both the directseeded and transplant plots. The increased height growth under weeded conditions was common to both, as well as for all species combined. These two cases provide some support for the inhibition model, the oak bias in the seed plots must be considered when all species are combined. Sweetgum demonstrated an interesting contradiction in response to treatments from the seed and transplant experiments. Growth data from the seed plots favored the initial floristics model, as none of the treatment means were significantly different. In the transplant plots, however, sweetgum growth was best in the weeded treatment, thus favoring the inhibition model. The results indicate another variable to consider; that is, that species may have different life history stages that respond differently to early colonizing species. If this is true, then the question of

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    149 addressing the pattern and process of ecosystem development becomes inextricably more complicated. However, the very low levels of germination/ survival of sweetgum in the seed plots caution against giving strong support to the results. Like sweetgum, cabbage palm also showed an opposite response to treatment effects from the seed and transplant plots. The seed plot data favored the acceptance of the initial floristics model, while the transplant plot results were not clearly weighed toward either the inhibition or relay floristics models. The two experiments can be seen to address the same fundamental issues of earliest succession at two succeeding stages of development. The direct-seeded plots simulated the critical period during the first growing season after propagules arrive at an open, uncolonized landscape. The proper cues must be made for germination, establishment depends on a suitable microenvironment , and adequate resources must be continually available for survival. The transplant plots mimicked the second growing season, the next stage in woody plant life, which is less precarious than germination and establishment but still heavily dependent on the quality of the microenvironment. The results of the experiments are strikingly similar for these two stages; in no case was germination or growth (as measured by height change) enhanced or increased by the presence of the natural or enhanced colonizer treatments. The results appear to offer strong

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    150 support for questioning the validity of the initial floristics and especially the relay floristics paradigms. It is somewhat surprising that the height growth results most strongly reject the relay floristics paradigm, as it was assumed at the outset to be important during the early stages of primary succession on phosphate-mined lands. Unvegetated overburden soils provide seeds and seedlings little amelioration or insulation from extreme physical conditions such as intense light, extremes of temperature, dessication, and erosion, that are sources of stress or mortality. The value of colonizing herbs in soil stabilization was demonstrated in the early part of the field tests, but the effect is not apparent in the results. Species Removal Several previous studies have examined the effects of species removal on the course of old-field succession. As with the seed and transplant plots of this study, research tends to support the view that succession cannot be succinctly explained by single-concept models. In a field experiment designed to test whether annual plants were needed to "prepare the way" for perennial plants, McCormick (1968) removed annual plants from a portion of a first-year-old field in Pennsylvania but allowed them to grow elsewhere. The subsequent biomass of individual perennial plants on the annual-free areas was many (15 to 82) times greater than on

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    151 areas with annuals. Using the decision criteria of Connell and Slatyer (1977), this experiment supports the inhibition model . Pinder (1974) studied the effects of the presence of the dominant grasses on the productivity of subordinate forbs within a perennial-grass, old-field community. He found that removing the dominants increased the net productivity of almost all subordinate species. Hils and Vankat (1983) used the species-removal approach to test Connell and Slatyer 's (1977) models in the first year of old-field succession. Their experimental treatments included removal of annuals, annuals and biennials, and perennials. Results from the first growing season favored acceptance of the initial floristics model, but the authors cautioned that more than one model of succession may apply in the same field at the same time, reflecting the spatial heterogeneity of the old-field community. The same old-field plots were further studied by Zimmerman and Vankat (1984). The species-removal treatments were maintained in the second year and the developing community was studied for the next three years. The initial floristics model was still supported at the end of 5 years because the authors found no statistically significant differences between the biomass of perennials grown with annuals and biennials and the biomass of those grown alone. Succession resulted in the development of nearly identical communities in the two treatments. The

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    152 two studies imply that the colonizing herbs had little effect on perennial herb species. None of the four studies found any support for the relay floristics model, but all dealt with only herbaceous plants in an old-field succession sequence. As noted earlier, relay floristics may be most appropriate for describing primary succession and the establishment and growth of late successional woody plants. The relay floristics model predicts that later successional woody species only enter the developmental cycle after harsh conditions have been ameliorated by the colonizing vegetation. The pioneer plant community is commonly assumed to play a role in the accumulation of soil organic matter, development of soil profiles, building of vegetation structure to provide shade and reduction of erosion from raindrops, buildup of soil nutrient levels, development of recycling from consumers, and development of symbiotic relations (plant/mycorrhizae, for example) . Evidence in support of the relay floristics model comes from studies of primary succession on newly exposed surfaces. Crocker and Major (1955) and Lawrence et al. (1967) have suggested that the characteristics of soils newly exposed by a retreating Alaskan glacier make the establishment of plants extremely difficult. Pioneer species that are able to colonize will ameliorate these conditions, reducing pH, increasing nitrogen, adding a layer of organic matter over the hardpan, and reducing

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    153 dessicating winds. Seedlings of spruce trees appear under the new conditions, but seldom, if ever, on the original exposed sites. Another example is the primary succession on sand dunes on lake shores (Cowles, 1899; Olson, 1958). Pioneer plants stabilize the moving sand, which otherwise would be unsuitable for colonization by later-appearing species. Competition Three experimental treatments (enhanced legume, natural colonizers, and enhanced colonizers) provided three levels of examining the issue of relay floristics versus competition. The natural colonizer treatment looks at relay floristics in the classical sense. The enhanced colonizer treatment tests the hypothesis that "more is better" for the establishment of climax species. The enhanced legume treatment tests the role of nitrogen-fixing species as colonizers. Tall, fast-growing legumes like Sesbania macrocarpa . S. punicea . and S. vesicaria could provide shade for young seedlings, attract pollinators, and provide perches for birds and cover for small mammals. It was assumed all these benefits could accelerate the rate of ecosystem development. With the exception of soil stabilization, none of these presumed benefits was as influential as the reduction in competition for resources during the first year of vegetation development at this particular site. It may be that scarce resources, such as moisture or soil nitrogen, limit vegetation

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    154 development and that the relatively slower-growing woody species show less vigorous growth when faced with herbaceous competitors. Because forest development is a long-term process (on the order of 50 to several hundred years) , the experimental plots provide a very controlled view of only the earliest stages. It is possible that the presumed benefits of the early colonizers take time to accrue and have an effect. The effect of litter may be an example. Foresters have long noted competition as a factor influencing successful reforestation. Toumey and Korstian (1931) note that a low, dense cover of grasses and herbs is a decided disadvantage to reforestation; not only does it provide a retreat for rodents and other seed-eating animals but, as soon as germination occurs, it directly competes with the young seedlings. The roots of the herbaceous competitors draw nutrients and water from the surface layers of the soil, and the intensity of competition often proves fatal to the trees. Competition has also been documented as a cause of decreased establishment and growth of tree seedlings in reclamation. Tackett and Graves (1983) cited competition by an herbaceous cover crop as a significant factor in reducing the height growth of tree seedlings. Vogel and Berg (1973) also found competition from herbaceous plants could be detrimental to growth of tree seedlings. Brown (1973) cited competition from herbaceous plants as one of the factors affecting germination and initial survival of seedlings.

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    155 Succession The preceding discussion of the field test results effectively illustrates the uncertainties and contradictions impeding interpretation of ecosystem development. The three paradigms of succession (relay floristics, initial floristics, and inhibition) are too rigidly and narrowly constructed. The field tests used in this study, which followed the experimental design of Connell and Slatyer (1979) , assume that the paradigms are mutually exclusive and that the pattern and course of succession is determined by only one. It is more likely that all three operate at some level during the course of succession. Hils and Vankat (1982) reached the same conclusion, finding that more than one model of succession may apply in one old-field at the same time reflecting the spatial heterogeneity of the old-field community. Connell and Slatyer 's (1977) approach appears to address only secondary succession. By omitting primary succession only implicitly, they further cloud the issue. As noted above, temporal factors need to be considered, and it is also likely that different paradigms may be appropriate at different stages of development. Role of fauna in succession . The Connell and Slatyer (1977) approach is also deficient in not considering the role of microand macrofauna in ecosystem development. Animals serve such functions in the community as seed dispersal, and

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    156 pollination. This study addresses the effect of moundbuilding ants in ecosystem development on mined lands; the role of earthworms in soil turnover and nutrient cycling provides another well-documented example of the influence of animals on vegetation development. Seed dispersal by animals, especially birds, is a potentially very important means for trees to invade disturbed areas. If the developing community provides the proper habitat requirements for seed-dispersing agents, then the invasion by later successional species may proceed much faster. Evidence of tree seed dispersal by birds can be seen in the woody flora found along almost any fence row, where seedlings of berry-producing species like black cherry (Prunus serotina) , hercules-club ( Zanthoxylum clava-heuculis ) , and sugarberry are quite common. In many of the central Florida citrus groves abandoned after the severe winter freeze of 1983, laurel oak and black cherry seedlings invaded within the first year or two, typically found beneath the standing-dead citrus trees. This invasion pattern was a result of the perch sites provided by the dead citrus trees and used by the seed dispersing birds. Field studies by McClanahan (1984) and Wolf (1986) indicate that seed dispersal to a large degree determines the rate at which forested ecosystems recover from catastrophic disturbances such as strip-mining. For animaldispersed seeds, site attractiveness appeared to be more important than distance.

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    157 Development of critical structure during primary succession . In primary succession on highly disturbed landscapes, the dispersal, arrival, and successful establishment of many late successional tree species may require some degree of "site preparation." The site attractiveness provides an excellent example of how seed dispersal is constrained until the site is suitable for the dispersal agent. Colonizing annuals, biennials, and herbaceous perennials do not offer attractive perch sites for many seed-dispersing birds. Many tree species have obligate or facultative symbiotic relationships with soil fungi, called mycorrhizae. The successful establishment and growth of some late successional tree species may be tied to presence of the appropriate fungal symbiont (Wallace, 1988) . The aboveground succession may be linked to a belowground succession. Caveats Finally, some degree of caution is needed in interpreting the first-year results from the Gardinier seed and seedling plots. Some of the most obvious considerations are as follows: 1. Results are from a single growing season but conclusions are extrapolated to the long-term process of ecosystem development. 2. Experimental treatments were fixed, not random; therefore, statistical inferences are appropriate only

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    158 to the treatment levels selected and not to a population of possible levels. 3. A limited number of tree species was used in the tests, and although the responses of the species differ, results are interpreted in terms of a whole forest. 4. Results are from a single set of tests carried out on one soil type at one site, so conclusions about the process of forest development must be couched in appropriate scope and scale. 6. Allelopathic effects of herbaceous species on each other and on woody plants may be important and were not investigated. 7. The weeding treatment may provide indirect benefits by disturbing the soil, increasing the rate of water infiltration by breaking up soil crusts commonly found on exposed overburden soils. 8. In the seeded plots it was easier to locate and measure seedlings in the seed plots receiving the weeding treatment. It is possible that some small seedlings were overlooked in the other treatment plots. So, then germination results would be biased in favor of the weeded treatment. Mound-Building Ants Mound Survey The mound densities measured in the survey ranged from 560/ha to 2,100/ha on 1 to 5-year old sites. Kangas (1983) found ant mound density increased dramatically over the first 10 years on unreclaimed phosphate-mined land, from 2,000/ha at 1 year to over 8,000/ha at a 10-year old site. Adams et al. (1978) estimated fire ant mound density in agricultural fields in Brunswick County, North Carolina, at 141 mature mounds per hectare. Baroni-Urbani and Kannowski

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    159 (1974) estimated the fire ant mound density of a Louisiana pasture at 96/ha. The relatively lower mound densities in these two studies may be a result of site-specific factors, but are more likely due to the authors' focus on large mature mounds . Kangas (1983) also noted a general increase in size of ant nests with increasing site age up to a point and then a later decline. For example, few ants were seen on a 50-yearold site. This observation may indicate a change or succession in the ant fauna through time as the vegetation, light levels, food quality, and physical and chemical character of the soil profile change. Ant Mound Roles Soil development . Mound building affects soil bulk density, particle size distribution, and the amount and distribution of pore space. The bulk density of soils from the 2-year old site showed mound values to be approximately 80 percent of the non-mound values, 1.19 g/cm^ versus 1.74 g/cm'. Wali and Kannowski (1975) measured the bulk density on mounds of seven species of ants on prairies in northeastern North Dakota and found the values to lie in a narrow range of 0.64 to 0.75 g/cm' in comparison to 1.15 g/cm' for non-mound prairie soil. Levan and Stone (1983) measured the bulk density of a black meadow ant ( Formica fusca) mound as 0.51 g/cm' .

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    160 A reduction in bulk density may make the soil a better rooting medium for established plants and possibly for germinating seeds, as soil aggregates will be broken down. Probably more important than absolute density differences is the effect of breaking the surface crust. This may be especially true on overburden soils, which tend to form very hard surface crusts, because of a higher clay content than native soils. Density changes are primarily a result of the movement of individual soil particles or grains, which increases pore space. Increased pore space can facilitate gas exchange, evaporation, and water infiltration. Mound building breaks up the crust aggregate, thereby increasing the pore space in the surface horizon. Concomitant with the surface effects of mound building is the creation of an elaborate subsurface system of chambers and tunnels. Tunnel systems extend as much as a meter or more below the mound and lateral channels may extend outward from the mound typically for a distance of several meters. The extensive tunnel system creates an anastomosing network of interconnected soil macropores that is maintained for the life of the mound. Some of the soil profile alterations resulting from ant activities may be lost temporarily during intense rainfall, but the mound and tunnel system are quickly repaired by the colony. Nest construction may cause more rapid alteration of the soil profile than would biogeochemical processes without

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    161 animals. Although mound construction is localized, a larger area affected is altered rapidly and extensively. Channelling below the mound produces an extensive interconnected network that penetrates the parent material. Deep channeling and vertical transport of soil material lead to an alteration of the soil. Some of the changes may persist for some time after mound abandonment. The channel system gradually collapses and the mound slumps, but soil alterations and nutrient availability may selectively favor certain plant species long after the mound has been abandoned. Levan and Stone (1983) estimate that pedoturbation by ants can be quite significant when viewed over the long term. Assuming an average mound density of 2,000/ha and an average mound basal area of 25 cm mounds occupy approximately 5 percent of the landscape. If it can be further assumed that the average life of a mound is approximately 2 years (Lofgren et al., 1975), then all the soil in a given area may be affected in 40 years time. Infiltration . An increase in infiltration rates beneficially alters the water balance of a developing community by preventing the loss of that scarce commodity, water. Water infiltration rates were higher in mound soils than non-mound soils in all measurements. The most obvious differences in the soil types were the pore space, texture, and bulk density.

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    162 Crusts commonly develop on the surface of overburden soils as they are alternately exposed to wetting and drying. The crust reduces infiltration and increases runoff relative to those areas where the crust has been broken. Crusting causes rainfall to pond on the soil surface, and blue-green algal mats commonly form on the most frequently ponded areas. Algal mats provide an additional barrier to water infiltration. Ehlers (1975) found that earthworm burrows reaching the surface improve water drainage. Ursic and Esher (1988) demonstrated that small mammal burrowing significantly increased water detention-retention in a pine-covered catchment and concluded that the numerous interconnected surface and subsurface burrows created a system that could accept and retain rain water until it was transmitted to deeper layers or moved into the soil matrix. In simulated rain study plots with short-tailed shrews (Blarina carolinensis ) and pine voles ( Pitymys pinetorum ) , they showed that burrowing activities decreased surface runoff by approximately 25 percent. ^ f -• ^ ' Ant tunnels are soil macropores. Dixon (1971) concluded that large pores can have a profound effect on the infiltration of water into soils. In a model developed to study pore size in relation to infiltration, Edwards et al. (1979) demonstrated that surface-connected holes can

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    163 effectively transmit water when more water is applied than can infiltrate. Nutrient cycling . Results of the chemical analyses support the hypothesis that foraging activity by ants elevates levels of some nutrients in the mound relative to adjacent non-mound areas. Confirmation of the nutrient concentration role of mound-building ants is one of the central points of a general model of the role of ants in ecosystem development (see Figures 4 and 5) . Fire ants have been extensively documented because of their status as nuisance pests. It is well established that fire ants are general landscape foragers with a diet consisting largely of protein from invertebrate prey supplemented with oils and fats from some plant parts (Lofgren et al., 1975). Foodstuffs are returned to the mound for consumption by the colony. The conceptual model predicts that because the ultimate fate of food materials is ant biomass and waste products, the mound should have relatively higher levels of organic matter and inorganic nutrients derived from microbial breakdown of organic matter in the mound. Soil chemical analyses showed enhanced nutrient pools in mounds and, therefore, support that pathway in the conceptual model. Generally higher levels of exchangeable cations, particularly potassium, have been reported from ant mounds by Czerwinski et al. (1969, 1971), Gentry and Stiritz (1972),

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    164 Rogers and Levigne (1974), and Wali and Kannowski (1975) . The statistically significant, higher levels of potassium mound soils are evidence of nutrient concentration by animals. Potassium may also come indirectly from phloem exudates via aphids (Levan and Stone, 1983) , on which fire ants are known to feed (Lofgren et al., 1975). Elevated sodium levels in mound soils are more perplexing. Sodium is a minor essential nutrient for animals but not for plants. It is also a readily solubilized ion from a variety of inorganic salts. It is possible that elevated levels of potassium and sodium may be the result of differences in evaporation rates between mound and non-mound soils. The lower bulk density and greater pore space of mound soils may facilitate evaporation of soil water, resulting in salt deposition. It is also possible that elevated levels of potassium and sodium in mound soils are caused by microbial decomposition of the organic matter in the mounds. The evaporation hypothesis remains one possible explanation of the elevated cation levels, but elevated organic matter and nitrogen levels provide additional support for the biological concentration argument. Lack of statistically significant differences for calcium and magnesium is not surprising, as overburden soils containing limestone and dolomite typically have high concentrations of these cations. Concentrations of calcium and magnesium ranged from several hundred to several thousand

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    165 grams per kilogram in overburden soils (Wallace, 1988) . The heterogenous nature of overburden soils led to considerable variation among samples. No clear differences in pH were observed between the two soil groups. Wali and Kannowski (1975) found ant activity increased pH in predominantly acid soils and decreased pH in predominantly alkaline soils. It is likely that there has not been sufficient time for ant activities to have an effect on the young overburden soils at the three sites studied. Also, the heterogeneous nature of these soils may contribute to a large statistical variance. It is expected that a pH reduction attributable to activities of the colony will become apparent through time. Plant growth enhancement . The results of the two plant growth experiments demonstrate that elevated nutrient levels in mound soil can translate into enhanced plant growth. The higher cations and nitrogen in mound soil enhanced growth for both a grass ( Paspalum urvillei) and woody plant ( Liouidambar stvracif lua ) . This supports the field observation that herbaceous plants, especially grasses, growing on mounds were more robust than those on adjacent nonmound soils. Indirect evidence is also provided to support the existence of non-trophic feedbacks as shown in the feedback loop between plants and ants (see Figures 4 and 5) .

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    166 Ant Model The importance of mound-building ants in a developing ecosystem appears to lie in the capture and cycling of potentially scarce resources, such as nutrients and water. Growth and development can be stimulated in two ways: (1) by additions or supplements of energy or resources and (2) by concentrating and recycling existing resources at a faster rate. It is the latter method that ants appear to facilitate. The results of the storages and pathways investigated support the ideas used to develop the conceptual ant model (see Figures 4 and 5) . Mounds were found to have elevated nutrient levels that, in turn, produced enhanced plant growth in greenhouse studies. Taken together, these results support the existence of a positive feedback loop between ants and primary producers. The existence of the other proposed feedback, the effect of ant-mediated pedoturbation on primary producers, appears to be supported by the infiltration tests. Indirect evidence of microbial pathways was found accumulations of organic matter and nutrients. Czerwinski et al. (1971) showed that enhanced organic matter levels in ant mounds increased activity of bacterial and fungal decomposers . Physical soil alterations resulting from mound building were not directly linked to enhanced plant growth, but indirect evidence comes from the beneficial effects of

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    167 biologically mediated soil turnover on plant growth (Gentry and Stiritz, 1972; Piatt, 1975). The effects of ants in a developing post-mining landscape will not be limited to the role of fire ants, as other soil fauna with both similar and different life histories are also present on these sites. In addition, the composition of the soil faunal community will likely change through time. Fire ants are an exotic species but do not appear to serve an exotic function. While they are able to displace other native species of ants, in their absence the native species can occupy these sites and serve the same function. Some other ant species may influence the developing ecosystem in similar ways at different stages. It is expected that as the post-mining landscape matures, ants may decline in dominance while earthworms gradually become more important components of the soil microfauna. Ants and earthworms may perform much the same function at different stages of succession. The two intensify different stages of decomposition; ants mainly with the first stages of mineralization and earthworms with humif ication. Petal (1978) has argued that the contribution of these two groups of animals to processes within the ecosystem and the range of their influence are functionally equivalent in environments with different fertility, plant productivity, rate of decomposition, and trophic complexity. In infertile soils with low organic matter and decomposition rates, like young

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    168 overburden soils, ants speed the return to the soil of nutrients accumulated in the bodies of other animals. The role of earthworms appears to be greater in fertile soils, characteristic of more mature ecosystems, where they speed the release of nutrients from the organic matter as it is being decomposed . Eclectic Synthesis of Paradigms and Implicatio ns for Reclamation Design Evidence reported in this dissertation supports the conclusion that both allogenic and autogenic forces act to change vegetation during primary succession on reclaimed upland and wetland sites. An encompassing paradigm of ecological succession must recognize the action of both forces and the interplay or feedback between them. With regard to the competing paradigms (initial floristics, inhibition, relay floristics, coevolution, and self-organization), studies reported here indicate that all are operating either simultaneously or at some time during succession on mined lands. It is likely that different paradigms may be appropriate at different stages of ecosystem development. There is no doubt that ecosystems can be studied either by examining one mechanism at a time or with a holistic, synthetic ecosystem approach and that valuable information is contributed by both approaches. It is premature to assert that a synthesis is not possible (Peet and Christiansen,

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    169 1980) , but it is clear that the synthesis is far from complete. The continuing contradictions about succession after many decades of study suggest that ecology and the succession concept may be in the midst of a change in paradigm. The single concept paradigms of succession (inhibition, initial floristics, relay floristics in particular) appear to be flawed and a new paradigm will likely emerge from a more eclectic synthesis that incorporates and unifies the concepts of several paradigms. It is clear that an explanation of the cause and mechanism of succession, and development of a reasonable consensus on a paradigm of succession, will require a careful analysis of the historical background, biases and premises, and philosophy of the idea and its practitioners, critics, and proponents. Until such time that a unifying paradigm of succession is constructed and widely accepted, it is also clear that the five competing paradigms examined in this dissertation can provide a theory-based guide for the reclamation of disturbed land. Reclamation should be viewed as type of engineering design based on ecological principles. The five paradigms reviewed in this dissertation can be used as ecological principles for guiding reclamation design. Using the paradigms to guide our reclamation design efforts should help us create functional, self-maintaining ecosystems that integrate with the surrounding landscape. A clear understanding of succession also provides an opportunity for

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    ; i . ,. * " :r ' , . , ^ ' '\ 170 forming rational and cost-effective land reclamation techniques and policies that will enhance and direct the successional process on mined lands. Using the five individual paradigms as design principles, some of the implications of each for the reclamation of strip mined land are discussed in the following section. Inhibition There are many documented examples of inhibited or arrested succession on mined lands. These studies generally describe an arrested succession in which the initial species composition of primary invading species is perpetuated. The Fort Green marsh study indicated that in the absence of disturbance, the initial vegetation pattern and species composition are maintained for some time, possibly even longterm. Initially established vegetation may be able to resist invasion by other species through maximum performance for existing environmental conditions. Under appropriate conditions, even slow-dispersing, late successional species are able to become established and occupy the available space. Once the available space is filled, opportunity for invasion, even by aggressive species capable of inhibiting succession, is limited. Consequently, it is feasible to establish self-maintaining, stable, wetland and upland communities

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    171 dominated by late successional species able to resist invasion by aggressive colonizers. The arrested, or inhibited, succession observed on mined lands may be largely attributable to restrictions on dispersal. It is apparent from the field studies reported here that late successional plant species can become established, grow, and survive under early successional conditions. The successional process on disturbed lands can be influenced and enhanced by facilitating the dispersal and establishment of the more slowly arriving, later successional components . For reclamation, the emphasis should be on: (1) predicting the soil type and soil moisture conditions (hydroperiod in wetlands) of the reclaimed system and using these as guides for determining the type of vegetation that could be supported; (2) controlling aggressive species capable of inhibiting succession; and (3) overcoming the dispersal limitation of many late successional species to get these species established at the start. On wetland sites, the application of peat or muck from donor marshes has been successful in these areas but may not always be feasible because of the quality of donor material or budgetary constraints in transporting the material. In such situations, planting an array of long-lived perennials in patches can accomplish these goals. At Fort Green large stands of cattail, pickerelweed, and bulrush developed from individual

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    172 plants or patches that gradually coalesced into larger units. A patch has to be of some critical size before it can be successfully established, and that the "critical" patch size probably changes as a function of the surrounding vegetation, the amount of open space available, and the growth rate of the species. On upland sites, woody species characteristic of later successional stages can be easily planted or seeded during early revegetation efforts. In some cases an arrested successional stage may be desireable, such as along utility line rights-of-way. If so, then revegetation efforts can be targeted at enhancing the establishment of those species capable of arresting succession on disturbed lands. The use of grazing, mowing, and periodic burning can also be helpful tools for arresting succession. For instance, fire may be needed for preventing the encroachment of woody species into marsh systems. Initial Floristics Egler's initial floristic hypothesis portrays old-field succession as a seed bank response to a change in environmental conditions. Studies in this dissertation show that initial floristics is also an important factor during primary succession on upland and wetland sites. The initial floristic composition is an important determinant of the type of vegetation that develops following disturbance. The vegetation pattern, and species composition of the marsh

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    173 community at Fort Green was found to be a function of the interplay between the propagules available and the prevailing environmental conditions. The formation of a seed bank in created wetlands appears to be a relatively rapid process, beginning almost immediately after the land surface has been exposed, but the species present in the seed bank samples were predominantly the initial colonizing species. Notably absent were seeds of the late successional species: woody taxa, emergent macrophytes, submergent macrophytes, and free-floating aquatic species. The implication of the initial floristics paradigm for reclamation design is that within certain constraints the species composition of reclaimed upland and wetland communities can be influenced, an in particular late successional species can often be established from the start. For wetland systems, design should focus on the seed/propagule bank as a critical component of self -maintaining systems. The use of peat or muck from donor wetlands can provide an instant seed bank that contains seeds/propagules of early and late successional species. As shown by the success of the bulrush plantings at Fort Green, some perennial macrophytes can be easily established by planting. A diverse array of woody species can be successfully established by seedling plantings in both wetland and upland situations.

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    174 Relay Floristics In a few cases relay floristics has been demonstrated. The results from the Gardinier tree plots showed that during primary succession areas subject to erosion and/or unstable substrates require a cover crop or nurse crop of early successional species in order to stabilize the substrate before later successional species can become established. In most areas, natural colonization by rapidly dispersing species will typically provide a cover crop within the first growing season. In areas subject to erosion, reclamation efforts should enhance and accelerate establishment of a cover crop. Seeding is one commonly used method. Spreading of topsoil/muck from donor upland/wetland sites is another method . Coevolution Within the constraints of resource supply or other environmental factors the autogenic, biological system is characterized by strong positive feedbacks among its components. Classic mutualisms exist between plants and mycorrhizal fungi, pollinators, and seed dispersers to name a few examples, but there are also the extended mutualisms that exist between plants and their rhizosphere, as well as the interactions that may not fit the standard definition of mutualism at all, but nonetheless are characterized by strong

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    175 mutualism at all, but nonetheless are characterized by strong positive feedback among the system components. The fire ant model may be an example of this latter type of positive feedback relationship. Severe disturbances, such as stripmining sever these links; re-establishing these links should be an important part of land reclamation. As discussed earlier, the maturation process within a developing community largely results from autogenic processes. One implication of this for reclamation design is that mature ecosystems have accumulated structure, and in many cases some of this critical structure can be added during reclamation. The application of muck from a donor wetland provides not only a propagule bank of seeds and rhizomes but structure in the form of the organic material itself and its attendant microbial and microfaunal component. As noted in the studies reported in this dissertation, other kinds of autogenically produced structures can be critical to development of communities in a primary succession. Some of these critical structures can also be added to the reclaimed system. Specific plantings to augment food or cover, placement timber or brush piles to augment cover, or placement of structures to provide nesting and resting sites may improve site attractiveness for seed dispersing fauna on both upland and wetland sites. Implicit in the the use of these techniques is the assumption that they are cost-effective, that the cost of adding structure will be more than paid for in the benefits

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    ' ' ^gww r y \ 176 derived. Further study and analysis will be required to make that determination, as the issue was not addressed in this dissertation. In addition to seed dispersal, animals serve many other functions in the community such as pollination, nutrient cycling, and substrate turnover. The fire ant study demonstrated the beneficial effects of soil fauna on chemical and physical properties of overburden soils. Recovery of ecosystems after severe disturbance includes re-establishing the below-ground community and processes, and coupling the above-ground succession with the below-ground succession. Reclamation activities should encourage the formation of a diverse soil fauna. Factors likely to contribute to the return of a rich soil fauna which can be easily incorporated into a reclamation design include: (1) vegetation of high species richness, (2) a high plant cover, and (3) a widespread and thick litter layer over at least part of the area, and the presence of some logs and standing dead wood. For example, specific plantings can help with the first two items and trees, topsoil, litter and woody debris from the pre-mining land-clearing operations can be stockpiled and reused later to create litter patches, brush-piles and downed logs. Self-Orcfanization In the self-organization paradigm, the actual species composition of the community is a function of the system's

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    177 self-organizing choices. It is believed that diversity stabilizes many ecosystem during environmental fluctuations or other periods of potential stress, buffering the system by providing more self-organizational choices, that extend the range of environments in which community structure and processes, such as energy flow, can be maintained. Seed/propagule banks and accumulated below-ground structures (e.g., roots, rhizomes) provide a storage of "choices" for all environmental contingencies, providing some support for the self-organization paradigm. In wetland and upland communities, seed banks provide a mechanism for rapid recovery from catastrophic mortality resulting from fire, clear-cutting, and drought. The rapid response of seed banks to environmental change minimizes interruptions to the energy flow in the community helping to maximize overall primary production. A relatively continuous flow of energy through an ecosystem, even during recovery periods, prevents an uncoupling of the above-ground and below-ground components, since many rhizosphere processes depend upon energy inputs from the above-ground community. It appears that many mature, self-maintaining wetland and upland systems contain a sufficient number of "choices" to meet a variety of environmental contingencies. Duplicating, or mimicking the "choices" found in many natural ecosystems by incorporating diversity into reclamation may prove to be a valuable design principle for creating self -maintaining

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    178 systems. The reclamation design principle then is to create wetland and upland systems that contain (1) a variety of habitat conditions with a variety of soil types and soil moisture conditions, and some variation in microtopography ; (2) a diverse assemblage of plants with many representatives of all life history strategies; (3) habitat conditions needed to enhance the formation of a diverse soil fauna; and (4) habitat conditions needed to enhance the use of the site by a diverse assemblage of wildlife. Once the reclamation effort has provided a diverse array of choices, then the system can "choose" the actual species composition of the community.

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    CONCLUSIONS The following points summarize the major conclusions relating to the wetland and upland field studies and their implications for reclamation and the paradigms of succession: 1. The application of muck from a donor wetland provides not only a propagule bank of seeds and rhizomes but structure in the form of the organic material itself and its attendant microbial and microfaunal component. 2. The development of the seed bank within the wetland, as seen by the spread of bulrush and Sagittaria . demonstrates the workings of an autogenic process and may provide one measure of community maturity. The spread of bulrush and Saaittaria also indicates that emergent macrophyte species other than cattail are capable of invading open mineral soils in reclaimed marshes . 3. The studies of wetland community development at Fort Green show that the marsh communities resulting from the muck treatment had a different species composition than those arising by natural succession. These community differences also proved to be stable for the first four growing seasons. 179

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    180 4. Under appropriate conditions, even slow-dispersing marsh species are able to become established and occupy the available space. Once the available space is filled, opportunity for invasion, even by aggressive weedy species like cattail, is limited. 5. Marsh studies at the Fort Green site have shown the value of documenting specific site histories, beginning if possible with an unvegetated substrate. Long-term studies provide the best view of ecosystem development. 6. The Gleasonian model proposed by van der Valk (1981) appears to have merit as a partial descriptive paradigm of wetland species composition in secondary succession. It does not recognize the autogenic processes that can feedback to and influence the "environmental sieve." 7. Evidence was found in the upland tree seedling plots to support the operation of all paradigms: inhibition, initial floristics, relay floristics, coevolution, and self-organization. A unified paradigm that the ideas of all five paradigms will provide an eclectic resolution to the controversy. > r' 8. Field studies show that mound-building ants can influence soil structure, runoff and soil infiltration, nutrient cycling, plant growth, and plant species distribution. Similar effects have been documented for the soil fauna in other ecosystems. 9. The arrested succession observed by many researchers on

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    181 mined lands may be largely attributable to restrictions on dispersal. Late successional plant species in marsh, swamp and upland ecosystems can become established, grow, and survive under early successional conditions. The successional process on disturbed lands can be influenced and enhanced by facilitating dispersal and adding the more slowly arriving components. The upland forest seed plots show that good germination results can be obtained with direct seeding. Until recently, the industry has not had much success with getting seeds to germinate and survive. While direct seeding of woody plants has been shown to be feasible, it has not been demonstrated to be a cost-effective reclamation technique. Very small seedlings appear to be more vulnerable to stress and mortality than larger seedlings.

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    192 Webster, J. R. , J. B. Wade, and B. C. Patten. 1974. Nutrient cycling and the stability of ecosystems, pp 1-27 In F.G. Howell, J. B. Gentry, and M. H. Smith (eds.). Mineral Cycling in Southeastern Ecosystems. CONF-740513. NTIS, Springfield, Virginia. Weller, M. W. 1981. Freshwater Marshes. University of Minnesota Press, Minneapolis, Minnesota. 146pp. White, P. S. 1979. Pattern, process, and natural disturbance in vegetation. Bot. Rev. 45:229-299. Whittaker, R. H. 1953. A consideration of climax theory. Ecol Monog 23:41-78. Wiken, E. B. , K. Broersma, L. M. Lavkulich, and L. Farstad. 1976. Biosynthetic alteration in a British Columbia soil by ants ( Formica fusca Linne) . Soil Sci. Soc. Amer. Proc. 40:422-426. Wilson, D. S. 1980. The Natural Selection of Populations and Communities. Benjamin Cummings, Menlo Park, California. 186 pp. Wilson, N. L. , J. H. Collier, and G. P. Markin. 1971. Foraging territories of imported fire ants. Ann. Entomol. Soc. Amer. 64:660-665. Witkamp, M. 1971. Soils as components of ecosystems. Ann. Rev. Ecol. Syst. 2:85-110. Wolf, R. W. 1986. Seed dispersal and wetland restoration. M.S. Thesis. University of Florida, Gainesville. Zellars-Williams and Conservation Consultants. 1980. Evaluation of pre-July 1, 1975 disturbed phosphate lands. Florida Department of Natural Resources, Tallahassee, Florida. 107pp. Zimmennan, D. M. and J. L. VanKat. 1984. Effects of species removals on an old field community: A five-year examination of successional mechanisms. Bull. Ecol. Soc. Am. 65(2) :65.

    PAGE 201

    BIOGRAPHICAL SKETCH Mr. Dunn was born on January 23, 1954, in Summit, New Jersey. After completing elementary and secondary education in New Providence, New Jersey, he entered Tufts University in 1972, where he majored in biology and received the Bachelor of science degree in May 1976. From May 1976 through September 1977, he was employed as an herbarium assistant in the Phippen-Lacroix Herbarium at Tufts University. His graduate training began at the University of Florida in the fall of 1977. He took a leave of absence from his graduate studies to work in environmental consulting in 1979 and 1980, then returned to complete the requirements for the degree of Master of Science in botany in 1981. In 1981, Mr. Dunn entered the Environmental Engineering Sciences Department at the University of Florida as a doctoral candidate. In the fall of 1985, he joined Environmental Services and Permitting, inc., as a senior scientist. He moved to the environmental consulting firm of CH2M HILL in 1986 and currently works as an environmental scientist with project management responsibilities in the areas of tertiary wastewater treatment using wetlands, water quality investigations, and general water resources issues. • ' He is married to Elizabeth Bondy. They have two handsome sons, Charlie and Sam. •= ' , 193

    PAGE 202

    I certify that I have read this study and that in my opinion it conforms to acceptable standards of scholarly presentation and is fully adequate, in scope and quality, as a dissertation for the degree of Doctor of Philosophy. G. Ronnie Best, Chairman Associate Research Scientist, Environmental Engineering Sciences I certify that I have read this study and that in my opinion it conforms to acceptable standards of scholarly presentation and is fully adequate, in scope and quality, as a dissertation for the degree of Doctor of Philosophy. Howard T. Odum Graduate Research Professor, Environmental Engineering Sciences I certify that I have read this study and that in my opinion it conforms to acceptable standards of scholarly presentation and is fully adequate, in scope and quality, as a dissertation for the degree of Doctor of Philosophy. Clay L. MontMue Associate Professor, Environmental Engineering .1 Sciences . , . I certify that I have read this study and that in my opinion it conforms to acceptable standards of scholarly presentation and is fully adequate, in scope and quality, as a dissertation for the degree of Doctor of Philosophy. Stephen R. Hunfphrej Professor, Forest Resources and Conservation

    PAGE 203

    I certify that I have read this study and that in my opinion it conforms to acceptable standards of scholarly presentation and is fully adequate, in scope and quality, as a dissertation for the degree of Doctor ofrsPhilosophy^ This dissertation was submitted to the Graduate Faculty of the College of Engineering and to the Graduate School and was accepted as partial fulfillment of the requirements for the degree of Doctor of Philosophy. May, 1989 Warren Viessman Professor, Environmental Engineering Sciences Dean , Col lege Engineering of Dean, Graduate School


    107
    Table 12b. Pignut hickory (Carva glabra)
    Plot Assignments PR>F
    for ANOVA (ANOVA)
    Treatment Means
    Weeded Natural Enhanced
    Legume Colonizers
    Plots 15 & 18
    Neglected
    NS
    6.25 5.61 5.61 5.17
    AAA A
    Plot 15 Weeded,
    18 Neglected
    NS
    5.87 5.61 5.61 5.17
    A A A A


    58
    Statistical Analyses
    All statistical analyses were run with the Statistical
    Analysis System (SAS). Data expressed as percent were
    transformed by the arcsine function.


    RESULTS
    59
    Marsh Development 59
    Seed Bank Survey 59
    Marsh Transect Study 72
    Upland Forest Succession Plots 90
    Seed Germination and Survival 90
    Height Growth in Seed Plots 105
    Height Growth in Transplant Plots 112
    Mound-building Ants 114
    Mound Survey 114
    Plant Growth Study 114
    Chemical Soil Analyses 116
    Physical Soil Analyses 120
    DISCUSSION 124
    Marsh Development 124
    Seed Bank Formation 124
    Formation and Stability of Macrophyte Communities.... 126
    Wetland Succession Model 132
    Role of Life History Characteristics 132
    Importance of Allogenic and Autogenic Factors 132
    Eclectic Wetland Succession Paradigm 135
    Upland Forest Succession Plots 139
    Seed Germination and Survival 139
    Height Growth 146
    Species Removal 150
    Competition 153
    Succession 155
    Caveats 157
    Mound-Building Ants 158
    Mound Survey 158
    Ant Mound Roles 159
    Ant Model 166
    Eclectic Synthesis of Paradigms and Implications for
    Reclamation Design 168
    Inhibition 170
    Initial Floristics 172
    Relay Floristics 174
    Coevolution 174
    Self-organization 176
    CONCLUSIONS 179
    REFERENCES 182
    BIOGRAPHICAL SKETCH 193
    v


    114
    were both significantly different from and higher than the
    enhanced treatment mean.
    When growth data were summed over species, the results
    were the same as for sweetgum and live oak. The mean for the
    weeded treatment was significantly different and higher than
    the means for the other three treatments, which were not
    significantly different from each other.
    Mound-Building Ants
    Mound Survey
    The field surveys showed mound densities of 560/ha,
    2,070/ha, and 2,100/ha for the 1-, 2-, and 5-year old sites,
    respectively. Average mound volumes were 600 cm3, 2,420 cm3,
    and 1,250 cm3 for the 1-, 2-, and 5-year old sites,
    respectively.
    Plant Growth Study
    The results of the vasey grass growth test (Table 14)
    show a uniform trend of significantly different and higher
    growth rates for the plants grown on mound soil for all three
    sites. A statistically significant growth enhancement was
    found in all three cases for the aboveground, belowground, and
    total plant biomass. For all comparisons, the mean biomass
    value for the mound samples was higher and significantly
    different (p < .01).


    145
    three models. Hickory and sweetgum exhibited no significant
    differences in survival under any of the four treatments,
    which provides support for the initial floristics model. The
    results may be influenced by the generally very low survival
    values, as some plots had only a single individual or none at
    all.
    Germination and survival results for sugarberry do not
    clearly favor any of the three models, and also may have been
    affected by generally low numbers of seeds germinating and
    surviving (less than 6 percent overall).
    Cabbage palm germination results appear to reject the
    relay floristics model but do not clearly favor either initial
    floristics or inhibition. The weeded mean was higher than the
    means for the two enhanced colonizer treatments (legumes and
    old-field weeds) but the mean was not different from the
    colonized treatment where the treatment seeds were added
    naturally.
    The results for oak also do not clearly support any of
    the three models, although there is some support for rejecting
    the relay floristics model. The weeded, natural colonizer,
    and enhanced legume means were significantly different from
    and higher than the enhanced colonizer mean, but the three
    means were not different from each other. Once again, the
    enhanced treatment came out lowest, raising the question of
    whether competition, allelopathy, or another form of
    inhibition was involved because of the species added in this


    Table
    . Summary of transect distance, elevation range, and inundation frequency of
    establishment zones for Pontederia cordata and Typha sp. on marsh transects
    at Fort Green wetland reclamation demonstration project; and summary of
    transect distance, elevation range, and inundation frequency of muck treatment
    zones on transects 97, 105, and 139.
    luck Treataeat Traaiecta Orerburdea Soil Traaaocta
    97
    10S
    119
    US
    125
    130
    Poatederia cordata
    Iaitial ippearaaca (dlataace )
    90 to ISO
    0 to 104
    67 to 07
    52 0 02
    225
    72
    litabliikaeat loaa {dlataace )
    90 to ISO
    0 to 104
    07 to 01
    21 to 04
    225 0 390
    72
    lleratioa laaia ( ail)
    36.11 to 36.33
    3S.S0 to 36.39
    16.50 to 30. 00
    36.36 to 36 45
    16.4 0 30.51
    30 40
    Iaiadatloa Frequeacj
    00 to 850
    7S to 1000
    0 to 350
    70 to 750
    00 to 750
    750
    Tjpba ap.
    Iaitial ippearaace (diataace a)
    US to 100
    75 to US
    70 1 00
    45 to 00
    75 to 120
    02 to 05
    latabllihaeat loaa (dlataace a)
    9S to 12S
    OS to US
    0 to 01
    32 to 05
    49 to 122
    0 to 62
    lleratioa laife (a aal)
    36 27 to 36 36
    36 10 to 30.42
    30.45 to 16.50
    36.40 to 30.50
    30 10 to 30.50
    10.30. to 30.50
    Iaoidatioa Irt(itac)
    000
    70 to no
    45 to 700
    00 to 700
    40 to 000
    50 to 000
    luck Treataeat Area
    Traataeat loaa (dlataace a)
    90 to 100
    S to US
    50 to 00
    lleratioa laafa (a aal)
    36.10 to 10.OS
    35 69 to 30.19
    36 45 to 30.85
    Iauadatioa Frequeacj
    TO to 0S0
    70 to 9S0
    0 to 700
    03
    VO


    143
    and Alnus glutinosa) and found that after 5 years, a greater
    number of oak seedlings were established than seedlings of
    the small-seeded species.
    Seedling Adaptations to Drought Stress. Seedling growth
    form can be especially important in determining the fate of
    germinating seeds. Along with its tough, leathery leaf, the
    cabbage palm seedling possesses a thick, leathery root system
    and is well adapted to handling drought stress. The
    aboveground and belowground tissues are strong enough not to
    collapse under moisture tension. Conversely,the sugarberry
    seedling has a delicate stem and root that are more rapidly
    affected by moisture stress. It is thus reasonable to assume
    that sugarberry mortality would be higher than that of cabbage
    palm if dessication were a problem, as is the case on exposed,
    unvegetated, overburden soils.
    This analysis of seedling anatomy can be extended to the
    other taxa in the study. Sweetgum, like sugarberry, produces
    a seedling with delicate shoot and root and would be expected
    to be killed more easily by drought stress. Hickory and oak
    both produce a stout woody shoot and a tough fibrous root
    system that makes them better adapted for coping with water
    stress.
    The survival data for all species summed together showed
    that the enhanced colonizer treatment had the lowest values.
    Several factors may have influenced this outcome. Competition


    49
    groundsel (Baccharis halimifolia), dogfennel (Eupatorium
    capillifolium), and broomsedge (Andropogon virginicus).
    Four species were added in the enhanced legume treatment:
    Cassia obtusifolia Sesbania macrocarpa. Sesbania punicea,
    and Sesbania vesicaria. In the direct-seeded plots, 50 seeds
    of each legume were added for a total of 200 seeds per plot;
    110 seeds per legume, totaling 440 seeds per plot, were added
    to seedling plots receiving this treatment. In both cases,
    the seeding rate gave a density of 22 legume seeds/m2.
    Seeds for the enhanced colonizer and enhanced legume
    treatments were applied by mixing the seeds with some over
    burden soil from the plot and hand broadcasting the mixture
    onto the plots. The soil was disturbed by hand with rakes and
    cultivators, to mitigate the effects wind would have on
    surface spread seeds of these wind-dispersed species. All
    plots were subsequently disturbed as part of a preplanting
    treatment. Planting and preplanting treatments were carried
    out in December 1983.
    The weeding treatment was administered quarterly in
    March, May, June, and September for both the transplanted and
    direct-seeded plots. All colonizing plants were hand-weeded
    and removed from the plots.
    Heavy rains in the first month after planting created
    several erosion rills running through the plots. To prevent
    cross contamination by seeds washing out of one plot and into
    another, hay was spread on the magins of all plots that had


    66
    Table 6. Twenty species with highest importance values (IV)
    along with the relative density and relative frequency values
    used to calculate the IV. All data taken from Tables 3 and
    4.
    % %
    Relative Relative Importance
    Species Density Frequency Value
    Juncus effusus
    Polygonum punctatum
    Cyperus rotundus
    Ludwigia virgata
    Eupatorium compositifolium
    Unknown 1
    Eclipta alba
    Unknown 3
    Cyperus sp.
    Ptilimnium capillaceum
    Aster subulata
    Baccharis halimifolia
    Grass 4
    Unknown 2
    Juncus bufonius
    Cyperus brevifolius
    Ludwigia palustris
    Ludwigia leptocarpa
    Samolus parviflorus
    Hypericum mutilum
    84.00
    14.00
    98.00
    3.00
    9.50
    12.50
    4.00
    7.50
    11.50
    3.00
    6.60
    9.60
    0.50
    8.50
    9.00
    1.70
    3.80
    5.50
    0.30
    3.80
    4.10
    0.90
    2.80
    3.70
    0.70
    2.80
    3.50
    0.40
    2.80
    3.20
    0.36
    2.80
    3.16
    0.15
    2.80
    2.95
    0.13
    2.80
    2.93
    0.10
    2.80
    2.90
    0.07
    2.80
    2.87
    0.16
    1.90
    2.06
    0.12
    1.90
    2.02
    0.09
    1.90
    1.99
    0.09
    1.90
    1.99
    0.07
    1.90
    1.97
    185.00


    157
    Development of critical structure during primary
    succession. In primary succession on highly disturbed
    landscapes, the dispersal, arrival, and successful
    establishment of many late successional tree species may
    require some degree of "site preparation." The site
    attractiveness provides an excellent example of how seed
    dispersal is constrained until the site is suitable for the
    dispersal agent. Colonizing annuals, biennials, and
    herbaceous perennials do not offer attractive perch sites for
    many seed-dispersing birds.
    Many tree species have obligate or facultative symbiotic
    relationships with soil fungi, called mycorrhizae. The
    successful establishment and growth of some late
    successional tree species may be tied to presence of the
    appropriate fungal symbiont (Wallace, 1988) The aboveground
    succession may be linked to a belowground succession.
    Caveats
    Finally, some degree of caution is needed in interpreting
    the first-year results from the Gardinier seed and seedling
    plots. Some of the most obvious considerations are as
    follows:
    1. Results are from a single growing season but conclusions
    are extrapolated to the long-term process of ecosystem
    development.
    2. Experimental treatments were fixed, not random;
    therefore, statistical inferences are appropriate only


    Table 9. Seed germination in Gardinier seed plots as measured by seedling counts in
    March and October 1984 along with the total cumulative germination. Data
    given by species and treatment.
    Celtio laeiifata
    Lieeidaebar atiracifloa Carta i labra
    Sabal oalaetto
    Oaercua
    laliolia iraaditlora
    Ml)
    Treataeat
    lid plot
    Can lot lie
    trek Oct Total
    Ciialatiie Coaulatite
    larck Oct Total lard Oct Total
    Caaalatlte
    lard Oct Total
    Cuaolatiie
    lard Oct Total
    Coialatlto
    lard Oct Total
    Coialatlto
    lore! Set Total
    fikaiced
    1
    (
    ¡1
    Coloiiied
    11
    14
    15
    +-li if
    i H n
    41
    51
    1} 11 43 0 t
    MII
    Heeded
    1
    5
    1
    11
    t 3
    1 5
    3 t
    15 1
    1
    1
    6
    It
    2
    3
    i
    0
    3
    1
    1
    2
    5
    4
    1
    1
    2
    4
    3
    2
    4
    6
    a
    3
    4
    1
    1
    1
    1
    1
    |
    f
    It
    13
    11
    f
    11
    11
    11
    13
    15
    IT
    21
    41
    41
    42
    21
    50
    45
    41
    31
    0
    0
    0
    0
    0
    1
    I
    t
    0
    t
    0
    1
    22 51
    21 S2
    21 (I
    41 15
    fl
    |
    11
    31 21
    It
    11
    5
    14
    11
    20
    21
    0
    41
    40
    ft
    1ST
    110
    0
    1
    0
    111 24f
    231
    Leioaed
    4
    7 0
    7
    2
    1
    3
    1
    3
    4
    0
    5
    5
    If
    35
    42
    0
    0
    0
    26 44
    fl
    1
    t 5
    11
    0
    t
    0
    1
    4
    4
    t
    1
    t
    11
    41
    4i
    0
    0
    1
    21 51
    11
    It
    S t
    12
    1
    t
    0
    1
    5
    6
    I
    1
    1
    11
    42
    41
    0
    0
    0
    It 5f
    f9
    12
    14 2
    14
    1
    1
    3
    1
    1
    4
    t
    1
    1
    2(
    11
    51
    1
    1
    1
    4f 53
    It
    36 11
    44
    5
    1
    (
    t
    13
    It
    1
    21
    21
    11
    Iff
    190
    0
    0
    I
    III 219
    211
    135 41
    154
    IT
    If
    41
    12
    fl
    11
    0
    115
    15
    2TT
    S47
    131
    0
    0
    0
    111 Iff
    1121
    VO
    K>


    153
    dessicating winds. Seedlings of spruce trees appear under the
    new conditions, but seldom, if ever, on the original exposed
    sites. Another example is the primary succession on sand
    dunes on lake shores (Cowles, 1899; Olson, 1958). Pioneer
    plants stabilize the moving sand, which otherwise would be
    unsuitable for colonization by later-appearing species.
    Competition
    Three experimental treatments (enhanced legume, natural
    colonizers, and enhanced colonizers) provided three levels of
    examining the issue of relay floristics versus competition.
    The natural colonizer treatment looks at relay floristics in
    the classical sense. The enhanced colonizer treatment tests
    the hypothesis that "more is better" for the establishment of
    climax species. The enhanced legume treatment tests the role
    of nitrogen-fixing species as colonizers. Tall, fast-growing
    legumes like Sesbania macrocarpa. S. punicea. and S. vesicaria
    could provide shade for young seedlings, attract pollinators,
    and provide perches for birds and cover for small mammals.
    It was assumed all these benefits could accelerate the rate
    of ecosystem development.
    With the exception of soil stabilization, none of these
    presumed benefits was as influential as the reduction in
    competition for resources during the first year of vegetation
    development at this particular site. It may be that scarce
    resources, such as moisture or soil nitrogen, limit vegetation


    99
    Table lib. Pignut hickory (Carya glabra)
    Treatment Means
    Plot Assignments
    for ANOVA
    PR>F
    (ANOVA)
    Weeded
    1
    Natural
    Enhanced
    Legume Colonizers
    Plots 15 & 18
    Neglected
    NS
    16.080
    A
    17.390
    A
    14.292
    A
    10.897
    A
    Plot 15 Weeded,
    18 Neglected
    NS
    16.167
    A
    17.390
    A
    14.292
    A
    10.897
    A


    175
    mutualism at all, but nonetheless are characterized by strong
    positive feedback among the system components. The fire ant
    model may be an example of this latter type of positive
    feedback relationship. Severe disturbances, such as strip
    mining sever these links; re-establishing these links should
    be an important part of land reclamation.
    As discussed earlier, the maturation process within a
    developing community largely results from autogenic processes.
    One implication of this for reclamation design is that mature
    ecosystems have accumulated structure, and in many cases some
    of this critical structure can be added during reclamation.
    The application of muck from a donor wetland provides not only
    a propagule bank of seeds and rhizomes but structure in the
    form of the organic material itself and its attendant
    microbial and microfaunal component. As noted in the studies
    reported in this dissertation, other kinds of autogenically
    produced structures can be critical to development of
    communities in a primary succession. Some of these critical
    structures can also be added to the reclaimed system.
    Specific plantings to augment food or cover, placement timber
    or brush piles to augment cover, or placement of structures
    to provide nesting and resting sites may improve site
    attractiveness for seed dispersing fauna on both upland and
    wetland sites. Implicit in the the use of these techniques
    is the assumption that they are cost-effective, that the cost
    of adding structure will be more than paid for in the benefits


    120
    The organic matter analysis was less determinate but
    indicated some of the same trends. At the 1-year old Tiger
    Bay site, the mean difference for soil organic matter was
    significantly different (P < 0.5) and positive. Positive
    differences were also shown for 2-year old Fort Green site (27
    percent) and the 5-year old Clearsprings site (15 percent),
    but these differences were only significant at marginal
    levels (P < .20)
    Physical Soil Analyses
    Bulk density. Bulk density measurements (Table 17) on
    soils from the one site that was sampled, the 2-year old Fort
    Green site, showed a statistically significant difference
    between the means for the mound and non-mound samples. The
    mean bulk density of the mound samples was 1.19 g/cm3,
    compared to 1.74 g/cm3 for the non-mound samples.
    Mound volumes can be calculated from circumference and
    height measurements, assuming a conical mound shape. Volumes
    range from 50 to 2850 cm3. Based on a average bulk density of
    1.2 g/cm3, a mound of average volume (approximately 1250 cm3*
    has a soil mass of approximately 1,500 g.
    Infiltration Tests. Results of the three water
    infiltration tests at the Fort Green site (Table 18) showed
    the infiltration rate on mound soils to be considerably higher
    than on the adjacent non-mound soils. Mound soil infiltration


    47
    Upland Forest Studies
    An upland area on the west side of Parcel 6 at
    Gardinier Phosphate Company's Whidden Creek Mine (Figure 6)
    was cleared in late October 1983. The cleared area was 63 m
    by 63 m with a gentle slope from the south to the north.
    Seedling and direct-seeded plots were located in early
    December 1983 and two experiments were set up adjacent to
    each other (Figure 8). The experimental design was a nested
    analysis of variance with four experimental treatments:
    colonizing species allowed, colonizers weeded out, colonizers
    added, and legumes added. Within each of the two experiments
    were four replicates for each treatment, for a total of 32
    plots. All treatments were randomly assigned to plots.
    The experimental treatments used in both the
    seedling and direct-seeded plots were the addition of seed of
    four colonizing species, the addition of seed of four legume
    species, the removal of all colonizing species through
    weeding, and a natural invasion of colonizing species. The
    first two treatments involved the application of seed, which
    was completed just prior to planting the tree seeds or
    seedlings. The initial site clearing in October left all
    plots free of vegetation at planting time.
    The enhanced colonizer treatment included four of
    the most common species found on old fields and abandoned mine
    lands in central Florida: natal grass (Rhvnchelvtrum repens),


    10
    A major influence of Clements' ideas on wetland ecology
    was the tendency to interpret zonation patterns in wetlands
    as indicators of future successional trends. Succession in
    wetlands was viewed as a directional, autogenically-driven
    process leading inevitably to some terrestrial climax.
    Evidence leads to the conclusion that both allogenic and
    autogenic processes act to change wetland vegetation and that
    the Clementsian idea of a regional terrestrial climax for
    wetlands is often inappropriate.
    Van der Valk (1981) claims that Pearsall (1920) was one
    of the first to apply Clements' concept of succession to
    wetlands. The concept of the monoclimax was eventually
    replaced by Whittaker's concept of pattern climax (Whittaker,
    1953), which was based on gradient analysis studies that
    documented the independent distribution of species along
    environmental gradients. The effect was to de-emphasize the
    successional interpretation of seres, or vegetative zones in
    the case of wetlands, and to focus on the correlation of plant
    species with specific types of environmental conditions.
    Van der Valk (1981) proposed a "new" definition of
    wetland succession, based on the ideas of H.A. Gleason (1917,
    1926, 1939) that did not presuppose the existence of a climax
    vegetation. Van der Valk defined succession as a change in
    the floristic composition of the vegetation of an area from
    one year to another which, is narrower than Gleason's
    definition of it as any change, quantitative or qualitative,


    105
    In the second ANOVA configuration, in which plot 15 was
    assigned to the weeded treatment and plot 18 was ignored,
    sugarberry and oak showed similar but not identical patterns.
    The means were not significantly different for sugarberry for
    the weeded and enhanced legume treatments or among the legume,
    natural colonizer, and enhanced colonizer treatments. The
    weeded and enhanced means were different, with the enhanced
    colonizer value the lower. For oak, the weeded, natural
    colonizer, and enhanced legume treatment means were not
    different from each other and all were significantly different
    from and higher than the enhanced treatment mean.
    Cabbage palm exhibited significant differences between
    some treatment means, but the results were the same for both
    ANOVA configurations (Table Ilf). The means for the weeded
    and natural colonizer treatments were not significantly
    different, and the natural colonizer, enhanced colonizer, and
    enhanced legume means were not significantly different, but
    the weeded mean was different from and higher than the legume
    mean.
    Height Growth in Seed Plots
    Height growth data from the seed plots were analyzed in
    the same manner as the survival data for each individual
    species and for the sum of all species (Table 12). When the
    height data were summed over species, the ANOVA results were
    the same in both combinations of assigning plots 15 and 18


    181
    mined lands may be largely attributable to restrictions
    on dispersal. Late successional plant species in marsh,
    swamp and upland ecosystems can become established, grow,
    and survive under early successional conditions. The
    successional process on disturbed lands can be influenced
    and enhanced by facilitating dispersal and adding the
    more slowly arriving components.
    10. The upland forest seed plots show that good germination
    results can be obtained with direct seeding. Until
    recently, the industry has not had much success with
    getting seeds to germinate and survive. While direct
    seeding of woody plants has been shown to be feasible,
    it has not been demonstrated to be a cost-effective
    reclamation technique. Very small seedlings appear to
    be more vulnerable to stress and mortality than larger
    seedlings.


    117
    Table 15. Results of sweetgum growth bioassay on mound and
    non-mound soil from 1-year old site.
    Seedling Growth
    Parameter
    Mean for
    mound soil
    (n=5)
    Mean for
    non-mound soil
    (n=6)
    P
    Stem biomass (g)
    0.41
    0.14
    . 0001
    Root biomass (g)
    0.99
    0.42
    .0002
    Leaf biomass (g)
    0.34
    0.17
    . 0003
    Total biomass (g)
    1.73
    0.67
    . 0001
    Leaf area (cm2)
    89.68
    44.30
    . 0003
    Stem height (cm)
    13.4
    9.68 <
    .03


    185
    Egler, F. E. 1954. Vegetation science concepts, I: Initial
    floristic composition, a factor in old field vegetation
    development. Vegetatio 4:412-417.
    Ehlers, W. 1975. Observations on earthworm channels and
    infiltration on tilled and untilled loess soil. Soil
    Science 119:242-249.
    Erwin, K. L., G.R. Best, W. J. Dunn, and P. M. Wallace. 1985.
    Marsh and forested wetland reclamation of a central Florida
    phosphate mine. J. Soc. Wetland Sci. 5:87-104.
    Franklin, J. F., and M. A. Henstrom. 1981. Aspects of
    succession in the coniferous forest of the Pacific
    Northwest. In D. C. West, H. H. Shugart, and D. B. Botkin
    (eds.), Forest Succession: Concepts and Application.
    Springer-Verlag, New York. 517 pp.
    Gentry, J. B., and K. L. Stiritz. 1972. The role of Florida
    harvester ant Poqonomvrex badius in old field mineral
    nutrient relationships. Env. Entomol. 1:39-41.
    Gleason, H. A. 1917. The structure and development of the
    plant association. Bull. Torrey Bot. Club 43:463-481.
    . 1926. The individualistic concept of the plant
    association. Bull. Torrey Bot. Club 53:7-26.
    . 1939. The individualistic concept of the plant
    association. Am. Midi. Nat. 21:92-110.
    Griffin, B. C., and N. C. Mullins. 1972. Coherent social
    groups in scientific change. Science 112:959-964
    Grime, J. P. 1978. Plant strategies and vegetation processes.
    John Wiley and Sons, New York.
    Grime, J. P. and R. Hunt. 1975. Relative growth rate: its
    range and adaptive significance in a local flora. J. Ecol.
    63:393-422.
    Handel, S. 1976. Dispersal ecology of Carex pedunculata
    (Cyperaceae) a new North American myrmeccochore. Am. J.
    Bot. 63:1071-1079.
    Heinselman, M. 1981. Fire and succession in the conifer
    forests of northern North America. In D. C. West, H. H.
    Shugart, and D. B. Botkin (eds.), Forest Succession:
    Concepts and Application. Springer-Verlag, New York. 517
    pp.


    116
    The sweetgum growth bioassay also showed a uniform growth
    enhancement on the mound soil (Table 15) For all growth
    parameters measured (stem biomass, root biomass, leaf biomass,
    total biomass, leaf area, and stem height), the mean for the
    mound soil was significantly different (P < .05) and higher
    than the non-mound mean. For biomass and leaf area growth
    parameters, the means for the seedlings grown on the three
    mound soils were at least twice those of the seedlings on the
    non-mound soils.
    Chemical Soil Analyses
    Chemical analysis of mound and non-mound soils highlights
    some differences in several of the chemical parameters
    assayed. Because the sampling technique used was paired
    samples, results are presented as mean differences of each
    pair with the non-mound value subtracted from the mound value
    (Table 16) Positive differences connote higher values for
    the mound samples.
    pH values exhibited a wide range at each of the three
    sites but tended to be circumneutral as compared to the
    characteristically acid soils native to the region. The mean
    difference of pH values between pairs was not statistically
    different at any of the three sites.
    Calcium levels showed no statistically significant
    differences between sample pairs from any of the three sites.
    For magnesium and manganese, no statistically significant


    141
    No other seed predators were ever in evidence, although
    the freshly disturbed and seeded plots could have attracted
    birds and small mammals alike. Seed loss from predation is
    a process occurring regularly in natural systems.
    Effect of Seed Size. The germination and survival data
    (see Tables 9 and 10) highlighted some differences concerning
    seed size and seedling growth form. The species used in the
    seed plots fall into three categories based on seed size.
    Sweetgum has a small winged seed adapted for wind dispersal,
    and the small seed contains little food to nourish a young
    seedling after germination. Both sugarberry and cabbage palm
    have intermediate-sized seeds. The seeds have a fleshy
    exocarp to attract birds and mammals as dispersal agents, and
    both have modified cotyledons for food storage. Hickory,
    laurel oak, and live oak produce large, heavy seeds that
    obviously do not disperse far on their own. These species are
    highly dependent on animals for that function. Acorns and
    hickory nuts have large, starchy cotyledons that provide
    nourishment to the developing seedling, as well as to
    potential seed predators.
    The relationship between the food reserve of modified
    cotyledons and the survival rate of a germinated seed is
    striking. The large-seeded species had high rates of
    survival; 75 percent of all germinating hickories and 87
    percent of all oaks survived. In contrast, only 33 percent
    of the sweetgum individuals survived the first growing season.


    103
    Table Ilf. Cabbage palm (Sabal palmetto).
    Treatment Means
    Plot Assignments
    PR>F
    Weeded
    Natural
    Enhanced
    for ANOVA
    (ANOVA)
    Legume Colonizers
    Plots 15 & 18
    25.833
    18.155
    10.410
    11.910
    Neglected
    .0841
    A
    A
    B
    B
    B
    Plot 15 Weeded,
    27.040
    18.155
    10.410
    11.910
    18 Neglected
    .0300
    A
    A
    B
    B
    B


    29
    examined to test the hypotheses that (1) differences in the
    initial floristics in the two treatment areas (mucked versus
    unmucked) result in communities of very different species
    composition and (2) differences in the perennial macrophytes
    of the two different treatment areas would be maintained
    through time.
    Both seedbank and transect studies were used to evaluate
    the Gleasonian model of wetland succession proposed by van der
    Valk (1981).
    Upland Forest Development
    Upland forest studies examined the relationships between
    early colonizing plants and late successional trees on an
    unvegetated upland site. The colonizing annuals, biennials,
    perennials, and low shrubs found on old fields were designated
    early successional species. The interactions between early
    and late species were examined to determine which paradigms
    explained ecosystem development (inhibition, initial
    floristics, or relay floristics). Field plot experiments
    using species removal and addition were designed to determine
    the effect, if any, of colonizing vegetation on establishment,
    growth, and survival of tree species.
    Four treatments were used: (1) natural colonization, (2)
    enhanced colonization with seeds of several common old-field
    weeds, (3) addition of legume species, and (4) periodic
    weeding to keep the plots generally free of any colonizing


    64
    Table 5. Seed bank density data from Table 3 summarized
    across sites for species totals of density, relative density,
    frequency, relative frequency, and importance value.
    Density
    Total
    (mean #/m2)
    %
    Relative
    Density
    Sampling
    Site
    Frequency
    %
    Relative
    Frequency
    Importance
    Value
    Aster subulata
    1,126
    0.36
    0.20
    2.80
    3.16
    Baccharis
    halimifolia
    459
    0.15
    0.20
    2.80
    2.95
    Carex sp.
    125
    0.04
    0.07
    0.95
    0.99
    Cvperus brevifolius
    500
    0.16
    0.13
    1.90
    2.06
    Cvperus sp.
    2,209
    0.70
    0.20
    2.80
    3.50
    Cvoerus rotundus 12.207
    4.00
    0.53
    7.50
    11.50
    Cvperaceae ?
    84
    0.03
    0.07
    0.95
    0.98
    Echinochloa waiter!
    125
    0.04
    0.07
    0.95
    0.99
    Eclipta alba
    958
    0.30
    0.27
    3.80
    4.10
    Eupatorium
    compositifolium
    1,672
    0.50
    0.60
    8.50
    9.00
    Graohalium
    obtusifolium
    84
    0.03
    0.07
    0.95
    0.98
    Grasses, unknown #1
    167
    0.05
    0.13
    1.90
    1.95
    Grasses, unknown #2
    42
    0.02
    0.07
    0.95
    0.97
    Grasses, unknown #3
    84
    0.03
    0.07
    0.95
    0.98
    Grasses, unknown #4
    417
    0.13
    0.20
    2.80
    2.93
    Grasses, unknown #5
    1,625
    0.50
    0.07
    0.95
    1.45
    Grasses, unknown #6
    126
    0.04
    0.13
    1190
    1.94
    Hvdrocotvle
    verticillata
    42
    0.02
    0.07
    0.95
    0.96
    Hypericum iwtilUffl
    206
    0.07
    0.13
    1.90
    1.97
    Junqus effUS.US 257,587
    84.00
    1.00
    14.00
    98.00
    Juncus bufonius
    209
    0.07
    0.20
    2.80
    2.87
    mdwjgia Yiraata
    8,499
    3.00
    0.47
    6.60
    9.60
    Ludwjgia oalustris
    376
    0.12
    0.13
    1.90
    2.00
    Uidwiqia leptccarpa
    294
    0.09
    0.13
    1.90
    2.00
    Polygonum ounctatum
    8,588
    3.00
    0.67
    9.50
    12.50
    Ptilimnium
    capillaceum
    1,168
    0.40
    0.20
    2.80
    3.20
    Ruroex verticillatus
    42
    0.02
    0.07
    0.95
    0.97
    Samclqg parviflorus
    292
    0.09
    0.13
    1.90
    2.00
    scrpBhulariaceas ?
    42
    0.02
    0.07
    0.95
    0.95
    stellaria madia
    334
    0.10
    0.07
    0.95
    1.00
    Unknown species #1
    5,334
    1.70
    0.27
    4.00
    5.50
    #2
    376
    0.10
    0.20
    2.80
    2.90
    #3
    2,750
    0.90
    0.20
    2.80
    3.70
    Column total 308,000
    100.00
    7.07
    100.00
    200.00


    132
    Wetland Succession Model
    Role of Life History Characteristics
    Regenerative strategies and other life history
    characteristics are the foundation of van der Valk's wetland
    succession model. The plant community's response to climatic
    cycles of flood and drought and changing environmental
    conditions is analyzed through the life history char
    acteristics of the species residing in the seed bank. The
    environmental factors in the model act as a "sieve" and
    screen species from the seed bank. The life history
    characteristics considered in the model include: propagule
    longevity (short-lived dispersing or long-lived seed bank
    forming), life span of the established plant (annual or
    perennial), and propagule establishment requirements
    (germination under drawdown or flooded conditions) The model
    has generally been applied to succession in marsh systems, but
    would seem to be equally appropriate for forested wetlands.
    The addition of woody species could be easily accomplished by
    incorporating the appropriate life history characteristics for
    propagule longevity, propagule establishment requirements, and
    life span of the established plant.
    Importance of Allogenic and Autogenic Factors
    The van der Valk model is useful in describing some
    aspects of wetland succession and showing the importance of


    98
    Table 11. Comparison of mean percent germination/survival for
    four experimental treatments (weeded, natural
    colonizers, legume, enhanced colonizers) using arc
    sine transformed data. Means compared following
    an ANOVA, using Duncan's multiple range test.
    Means with the same letter are not significantly
    different (p =.05).
    Table 11a. All species summed
    Treatment Means
    Plot Assignments
    PR>F
    Weeded
    Natural Enhanced
    for ANOVA
    (ANOVA)
    Legume Colonizers
    Plots 15 & 18
    25.017
    23.567 22.857 19.027
    Neglected
    .0079
    A
    A A
    B
    Plot 15 Weeded,
    25.510 23.567
    22.857 19.027
    18 Neglected
    . 0031
    A A
    B
    B
    C


    20
    species known as myrmeccochores have a food body on their seed
    that is eaten by ants, which then disperse the seeds while
    returning food materials to the mound.
    Competing Paradigms of Succession
    The preceding discussions have revealed five competing
    paradigms of succession: two individualistic, life history-
    based models (initial floristics and inhibition) and three
    holistic ecosystem models (relay floristics, coevolution, and
    self-organization). An energy circuit language diagram of
    succession is shown in Figure 3a that includes early and late
    stage plants, seeding, and nutrient recycle. Additional
    controls and pathways are added to represent various paradigms
    for the interactions between early and late successional
    species (Figures 3b-3f). The concept of each paradigm is
    briefly summarized below.
    Initial floristics. Early and late successional species
    coexist with the same resources (Figure 3b) The early
    species modify the site so that it is not suitable for their
    continued reproduction, but have no effect on the recruitment
    of late species.
    Inhibition. Early and late successional species compete
    for available space and resources, such as light, nutrients,
    and moisture (Figure 3c). Rapidly dispersing, fast growing
    early species colonize available open space and capture
    available resources, inhibiting the establishment of later


    5
    disappears from areas where environmental conditions are no
    longer favorable.
    Egler (1954) also found fault with Clements' view of
    succession, but stressed the role of autogenic processes in
    old-field community succession. He applied the name "relay
    floristics" to Clements' sequential appearance and
    disappearance of groups of species and posed an alternative
    mechanism he termed "initial floristics" in which old-field
    plant community development after abandonment unfolds from an
    initial flora already residing within the soil, without
    additional increments by further invasion. As each successive
    d
    species or group subside, another that has been present from
    the beginning, assumes dominance. In a forest succession
    sequence, eventually only the trees are left. Egler noted
    that the actual development of vegetation in an old-field is
    a function of both autogenic processes but that in secondary
    succession, initial floristics determined the composition of
    the resulting community and relay floristics played a
    relatively minor role. He also noted that allogenic factors
    were important determinants of community composition.
    The Clementsian and Gleasonian views of succession define
    opposite poles within the field of ecology. In the modern
    analogs, the arguments have been refined but many of the key
    issues and differences have remained intact. The Clementsian
    tradition has a modern synthesis in systems ecology, while the
    modern proponents of the Gleasonian view are typically aligned


    Figure 17. Energy circuit diagram of a revised van der Valk's wetland succession model
    with feedback pathways added to indicate the influence of autogenic processed in
    modifying the effects and action of the environmental sieve (see Figure 2 for
    comparison).


    131
    Monitoring the fate of the drought-stressed or drought-
    killed macrophyte communities will provide some additional
    insight into community dynamics in future years. Major
    patches of cattail and pickerelweed senesced in response to
    the drought (Figures 15a through 15f). Only time will
    indicate whether the whole plant was killed or only the
    aboveground portions. If the latter is the case, then the
    drought may have only hastened the annual fall senescence, as
    the aboveground portions of both taxa annually die back and
    the plants overwinter as leafless rhizomes. Even if large
    patches were killed by the drought, species replacement may
    be slowed or inhibited by the presence of standing dead plant
    tissue; since as these studies have shown, an occupied space
    is difficult to colonize.
    The marsh transect study does not and cannot address the
    long-term stability of created marsh communities like the Fort
    Green site. There is no reason to believe that the marsh
    system will not eventually develop into a forested wetland.
    Tree seedlings planted within the wetland have done quite well
    through the first four growing seasons (Best and Erwin, 1984;
    Erwin et al., 1985). The mature marsh system may actually be
    an immature swamp system.


    16
    hypothesized feedback loops between species, termed indirect
    effects. Non-trophic interactions are concerned with
    ecosystem structure and function, which, according to the
    individual selection theories of traditional population
    ecology, are not subject to adaptive evolution.
    It has been suggested that heterotrophs regulate
    autotrophs and thereby control the rate of energy production
    ( O'Neil et al., 1975; Lee and Inman, 1975). Owen and Weigert
    (1976) asked the question, whether consumers maximize plant
    fitness, and developed a hypothesis that consumers, like
    pollinators, have a mutualistic relationship with plants. They
    suggested that plants may exploit consumers to increase
    fitness. If, through the action of consumers, a nutrient that
    is in short supply is made more available to the plant, the
    relatively small amount of photosynthate lost may be more than
    compensated.
    Mutualistic interactions may involve a direct trophic
    link, such as those just described, but other non-trophic
    interactions between species very much affect fitness but do
    not involve competition or predation. For example, intensive
    fiddler crab (Uca pugnax) activity in the tail-form of
    saltmarsh cordgrass (Spartina alterniflora) stands improves
    soil drainage, oxygenates marsh sediments, and increases
    belowground decomposition of plant-generated debris (Bertness,
    1985) all of which can affect the growth rate of the
    cordgrass.


    9
    of those already present. Invasion is only possible when the
    dominating species are damaged or killed, thus releasing
    resources. In model 3, the tolerance of late successional
    species is important, as it allows them to survive long
    periods of suppression.
    Wetland Succession
    Much of the debate on succession focuses on the factors
    controlling the course of community development. Controlling
    factors are typically grouped as autogenic, those generated
    by the biological community itself, or allogenic, coming from
    outside the biological community.
    In some views of succession (Clements, 1916, 1920)
    wetlands were considered a transient stage between aquatic
    communities and a terrestrial forest climax. In this concept,
    aquatic areas may gradually fill from sediment deposition and
    organic peat formation. Emergent macrophytes, shrubs, and
    trees gradually appear, and the community continues to
    transform the wetland site into a terrestrial one. Where
    sediment accumulation raises the ground elevation above water
    levels, a change to drier vegetation is observed.
    In wetlands where inorganic sediments are not being added
    and land is not being elevated, peat formation may not proceed
    beyond water levels (Odum, 1984). In warm climates, organic
    matter oxidizes or burns in dry weather, arresting succession.
    Many wetland ecosystems in this sense are a form of climax.


    46
    species to yield total cover, which can be standardized to
    percent cover.
    The modification of the standard method used in this
    study consisted of identifying patches or intervals of species
    occurrence even when the cover by the particular taxa within
    the patch was less than 100 percent. With this modified line-
    intercept technique, the interval distance as well as the
    percent cover by the taxa within the interval was recorded.
    The modification provided a more rapid method of measurement
    that was also relatively accurate and well adapted to
    measuring changes in vegetation across zones and following
    changes through time.
    The transects were sampled over four growing seasons:
    November 1982; May, July, and November 1983; March, July, and
    November 1984; and June 1985.
    Elevations along each transect were measured on 1.5 m
    intervals. These elevations were converted to mean sea level
    (msl) based on a reference to the measured surface water level
    in the wetland basin that day. A continuous water level
    record was provided by a surveyed, permanently mounted water
    level recorder. The daily summary values for the period of
    study were supplied by Agrico Mining Company.


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    182


    BIOGRAPHICAL SKETCH
    Mr. Dunn was born on January 23, 1954, in Summit, New
    Jersey. After completing elementary and secondary education
    in New Providence, New Jersey, he entered Tufts University in
    1972, where he majored in biology and received the Bachelor
    of Science degree in May 197 6. From May 197 6 through
    September 1977, he was employed as an herbarium assistant in
    the Phippen-Lacroix Herbarium at Tufts University. His
    graduate training began at the University of Florida in the
    fall of 1977. He took a leave of absence from his graduate
    studies to work in environmental consulting in 1979 and 1980,
    then returned to complete the requirements for the degree of
    Master of Science in botany in 1981. In 1981, Mr. Dunn
    entered the Environmental Engineering Sciences Department at
    the University of Florida as a doctoral candidate. In the
    fall of 1985, he joined Environmental Services and Permitting,
    Inc., as a senior scientist. He moved to the environmental
    consulting firm of CH2M HILL in 1986 and currently works as
    an environmental scientist with project management
    responsibilities in the areas of tertiary wastewater treatment
    using wetlands, water quality investigations, and general
    water resources issues.
    He is married to Elizabeth Bondy. They have two handsome
    sons, Charlie and Sam.
    193


    119
    differences were seen between sample pairs for the 1-year old
    and the 2-year old sites, but a significant positive
    difference was reported for the 5-year old Clearsprings site.
    Magnesium values were an average of 48.3 g/kg higher in mound
    soils than in non-mound soils. Manganese values were 2.5 g/kg
    higher in the mound soils.
    Potassium and sodium each had a statistically significant
    and positive difference at each of the three sites. For
    potassium, the mean difference was 94.5 g/kg for the 1-year
    Tiger Bay site, 55.5 g/kg for the 2-year site, and 79.3 g/kg
    for the 5-year site. The mean difference for sodium was 28.3
    g/kg for 1-year site, 24.8 g/kg for 2-year site and 7.0 g/kg
    for 5-year site.
    Nitrogen values followed the same pattern as potassium
    and sodium with statistically significant (P < .01) positive
    differences at all three sites. Mean differences for the
    mound and non-mound soils were 1,902, 764, and 1,843 g/kg for
    the 1-, 2-, and 5-year sites, respectively. Tiger Bay mound
    samples had a range of nitrogen levels from 2,429 to 4,039
    g/kg as compared to 539 to 2,709 g/kg for the non-mound soils.
    At the 2-year old Fort Green site, the ranges were 2,450 to
    3,325 g/kg and 1,995 to 2,870 g/kg for the mound and non-mound
    samples, respectively. For the 5-year old Clearsprings site,
    the ranges were 3,899 to 6,699 g/kg for the mound soils and
    1,869 to 5,089 g/kg for the non-mound soils.


    Table 2. Sample locations and site characteristics.
    Site
    County
    Vegetation Zone
    Substrate
    Unreclaimed Mine Site
    Sanlan marsh (30 yr old)
    Polk
    Juncus-Polvaonum
    Eichhornia
    Clay
    Clay
    Reclaimed Mine Sites
    Clearsprings (4 yr old)
    Polk
    Polvaonum-Ludwiaia
    Clay-overburden
    Fort Green (2 yr old)
    Polk
    Pontederia (Muck zone)
    Open water (Muck zone)
    Open water
    Muck-overburden
    Muck-overburden
    Overburden
    Four Corners Marsh
    (5 yr old)
    Manatee
    Pontederia (Muck zone)
    Pontederia (Planted)
    Eleocharis (Control)
    Polvaonum-Ludwiaia
    Muck-sand
    Sand
    Sand
    Sand
    Natural Wetlands
    Pasture marsh
    Polk
    Pontederia-Juncus
    Muck-sand
    Peace River bayhead
    Polk
    Saururus
    Peat
    Lake Kanapaha *
    Alachua
    Amaranthus
    Echinochloa
    Open water
    Muck-sand
    Muck-sand
    Muck-sand
    Four Corners marsh
    Manatee
    Pontederia-Juncus
    Muck-sand
    * Lake Kanapaha not sampled in this study, results from previous study provided
    by Dr. Ronald Myers


    150
    support for questioning the validity of the initial floristics
    and especially the relay floristics paradigms.
    It is somewhat surprising that the height growth results
    most strongly reject the relay floristics paradigm, as it was
    assumed at the outset to be important during the early stages
    of primary succession on phosphate-mined lands. Unvegetated
    overburden soils provide seeds and seedlings little
    amelioration or insulation from extreme physical conditions
    such as intense light, extremes of temperature, dessication,
    and erosion, that are sources of stress or mortality. The
    value of colonizing herbs in soil stabilization was
    demonstrated in the early part of the field tests, but the
    effect is not apparent in the results.
    Species Removal
    Several previous studies have examined the effects of
    species removal on the course of old-field succession. As
    with the seed and transplant plots of this study, research
    tends to support the view that succession cannot be succinctly
    explained by single-concept models. In a field experiment
    designed to test whether annual plants were needed to "prepare
    the way" for perennial plants, McCormick (1968) removed annual
    plants from a portion of a first-year-old field in
    Pennsylvania but allowed them to grow elsewhere. The
    subsequent biomass of individual perennial plants on the
    annual-free areas was many (15 to 82) times greater than on


    186
    Hils, M. H. and J. L. Van Kat. 1982. Species removals from
    a first-year old field plant community. Ecol.
    63(3):705-711.
    Hopp, H., and C. S. Slater. 1948. Influence of earthworms on
    soil productivity. Soil Sci. 66:421-428.
    Horn, B. 1971. The adaptive geometry of trees. Monog. Pop.
    Biol. 3. Princeton Univ. Press, Princeton, New Jersey.
    . 1974. The ecology of secondary succession. Ann. Rev.
    Ecol. Syst. 5:25-37.
    . 1975. Forest succession. Sci. Am. 232 (5):90-98.
    Humphrey, S. R. 1979. Biological communities recovering after
    mining. Paper presented at the Reclamation of
    Surface-Mined Lands in the Southeastern Coastal Plains
    workshop, September 10-11, sponsored by the Center for
    Environmental and Natural Resource Programs, Institute of
    Food and Agricultural Sciences, University of Florida,
    Gainesville.
    Hutchinson, G.E. 1942. Addendum to R. L. Lindeman. The
    trophic dynamic aspect of ecology. Ecol 23:417-418.
    Johnson, E. A. 1975. Buried seed populations in the subarctic
    forest east of Great Slave Lake, Northwest Territories.
    Can. J. Bot. 53:2933-2941.
    Kangas, P. 1979. Succession on spoil from phosphate mining.
    Center for Wetlands, University of Florida, Gainesville.
    . 1983. Energy analysis of landforms, succession,
    and reclamation. Ph.D. Dissertation, University of
    Florida, Gainesville.
    Keddy, P. A. and A. A. Reznicek. 1982. The role of seed banks
    in the persistence of Ontario's coastal plain flora. Amer.
    J. Bot. 69(1):13-22.
    King, T. J. 1977. The plant ecology of ant-hills in
    calcareous grasslands: II. Succession on the mounds. J.
    Ecol. 65:257-278.
    King, T. L. L. Hord, T. Gilbert, F. Montabano, and J. N.
    Allen, Jr. 1980. An evaluation of wetland habitat
    establishment and wildlife utilization in phosphate clay
    settling areas. IN R. R. Lewis and D. P. Cole (eds.),
    Seventh Annual Conference: The Restoration and Creation of
    Wetlands. Hillsborough Community College, Tampa, Florida.


    166
    Ant Model
    The importance of mound-building ants in a developing
    ecosystem appears to lie in the capture and cycling of
    potentially scarce resources, such as nutrients and water.
    Growth and development can be stimulated in two ways: (1) by
    additions or supplements of energy or resources and (2) by
    concentrating and recycling existing resources at a faster
    rate. It is the latter method that ants appear to facilitate.
    The results of the storages and pathways investigated
    support the ideas used to develop the conceptual ant model
    (see Figures 4 and 5) Mounds were found to have elevated
    nutrient levels that, in turn, produced enhanced plant growth
    in greenhouse studies. Taken together, these results support
    the existence of a positive feedback loop between ants and
    primary producers. The existence of the other proposed
    feedback, the effect of ant-mediated pedoturbation on primary
    producers, appears to be supported by the infiltration tests.
    Indirect evidence of microbial pathways was found
    accumulations of organic matter and nutrients. Czerwinski et
    al. (1971) showed that enhanced organic matter levels in ant
    mounds increased activity of bacterial and fungal
    decomposers.
    Physical soil alterations resulting from mound building
    were not directly linked to enhanced plant growth, but
    indirect evidence comes from the beneficial effects of


    142
    In the intermediate seed-size group, sugarberry had low
    survival while cabbage palm had the highest possible survival.
    The cabbage palm results may be anomalous, both because
    of the phenology of this species and the sampling schedule.
    During the first sampling period in March, no cabbage palm
    seedlings were present on any of the plots. All cabbage palm
    seedlings present in the October census had germinated between
    late spring and summer. Under this schedule cabbage palm
    seedlings had 100 percent survival. This could be misleading,
    because the cabbage palm seedling has a single, short, very
    leathery leaf, that resists decay for some time, even if dead.
    If cabbage palm seeds had germinated and the seedling later
    succumbed, the leaf could have remained long enough to be
    counted in the survey. Because there is no evidence to
    support this possibility, it is assumed that there may have
    been some slight mortality, but that survival rates for
    cabbage palm were high.
    The relatively superior performance of large-seeded
    species in direct-seeding trials has been noted in other
    studies. Tourney and Korstian (1942) noted that seeds
    containing a large amount of reserve food and germinating in
    early spring are better adapted for direct seeding than small
    seeds that are slow to germinate and produce plants of slow
    juvenile growth. Tackett and Grimes (1983) seeded three
    large-seeded species (Ouercus rubra, Q. palustris. and Q.
    macrocarpa) with two small-seeded species (Paulownia tomentosa


    37
    Figure 6. Location of study sites in Polk and Manatee
    Counties.


    102
    Table lie. Oak (Ouercus)
    Treatment Means
    Plot Assignments
    for ANOVA
    PR>F Weeded Natural Enhanced
    (ANOVA) Legume Colonizers
    Plots 15 & 18
    Neglected
    42.127 41.105 39.645 33.930
    .0604 A
    A A
    B
    Plot 15 Weeded,
    18 Neglected
    42.127 41.105 39.645 33.930
    0347
    B