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The longleaf pine islands of the Ocala National Forest, Florida

Material Information

Title:
The longleaf pine islands of the Ocala National Forest, Florida a soil study
Creator:
Kalisz, Paul John
Publication Date:
Language:
English
Physical Description:
xii, 127 leaves : ill. ; 28 cm.

Subjects

Subjects / Keywords:
Dissertations, Academic -- Soil Science -- UF
Forest soils -- Florida ( lcsh )
Longleaf pine -- Soils -- Florida ( lcsh )
Pine -- Soils -- Florida ( lcsh )
Soil Science thesis Ph. D
Ocala National Forest (Fla.) ( lcsh )
Ocala National Forest ( local )
Opal ( jstor )
Soils ( jstor )
Beetles ( jstor )
Genre:
bibliography ( marcgt )
theses ( marcgt )
non-fiction ( marcgt )

Notes

Thesis:
Thesis (Ph. D.)--University of Florida, 1982.
Bibliography:
Includes bibliographical references (leaves 120-126).
Additional Physical Form:
Also available online.
General Note:
Typescript.
General Note:
Vita.
Statement of Responsibility:
by Paul John Kalisz.

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Full Text











THE LONGLEAF PINE ISLANDS
OF THE OCALA NATIONAL FOREST, FLORIDA: A SOIL STUDY













BY


PAUL JOHN KALISZ





















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


UNIVERSITY OF FLORIDA 1982














ACKNOWLEDGEMENTS

I am grateful to E. L. Stone for the opportunity to study and work with him over the past five years. Under his guidance, I have received an education in forest soils that is hard to equal. I also thank R. F. Fisher, H. L. Gholz, R. W. Johnson, and W. L. Pritchett for serving on my committee. Special thanks to Barbara Fischer for the typing of this dissertation, to Craig Reed and Karen Williams for help in the field, and to Mary McLeod for organizational and

laboratory support.






























ii














PREFACE

This study is concerned with the soils of two

contrasting forest communities that share a boundary. Chapter I characterizes and compares these soils and shows that soil properties do not account for the occurrence of the two types of vegetation.

Chapter II deals with soil mixing by animals and

the effects of mixing on soil properties. In particular, it is demonstrated that such mixing influences the appearance of surface soil horizons. The distinctness of these horizons has contributed to the belief that longleaf and sand pine soils are fundamentally different. The latter chapter therefore expands on the point originally made in Chapter I, that the sometimes striking differences in the appearance of surface soil layers under longleaf and sand pine are not indicative of distinct substrates; rather, they are superficial alterations caused by differences in plant communities and associated animal assemblages.













iii















TABLE OF CONTENTS

Page

ACKNOWLEDGEMENTS . . . . . ....... ii

PREFACE . . . . . . . . . . . iii

LIST OF TABLES . . . . . . . . . vi

LIST OF FIGURES . . . . . . . . .viii

ABSTRACT . . . . . . . . . . . x

CHAPTER

I ORIGIN AND STABILITY OF LONGLEAF PINE
ISLANDS . . . . . . . . . 1

Introduction . . . . . . . 1
Study Area . . . . . .... 3
Location and Climate . . . . . 3 Geology ................ 3
Soils . . . . . . . . . 7
Vegetation . . . . . . . 7
Methods . . . . . . . . . 12
Field Methods . . . . . . . 12
Laboratory Analyses . . . . . 13
Opal Extraction . . . . . . 14
Nutrient Bioassay ............ 14
Results and Discussion ..........15
Surface Soil Profiles . . . . 15
Morphology . . . . . . . 15
Organic matter and charcoal . . . 25 Fertility . . . . . . . 32
Deep Soil Profiles . . ... . . 37
Morphology and texture . . . . 37 Chemical characteristics . . . 40
Opal . . . . . . . . . 49
Contents and morphology of opal
in plants . . . . . . . 50
Opal accumulations in longleaf
and sand pine soil . . ......... 52
Opal in soils of paired boundary
plots ........... ..... 55
Opal patterning around longleaf
pine islands . . . . . . 66



iv










Page

Stability of Present Boundaries ... 72
Geographical and Archeological
Evidence . . . . . . . . 76
General Discussion ..... ... . 79

II SOIL MIXING BY ANIMALS IN THE LONGLEAF
PINE AND SAND PINE COMMUNITIES ...... 84

Introduction ............. 84
The Beetle .......... . . 84
Materials and Methods ... .. ..... 85
Results and Discussion ......... 91
Soil Movement by Peltotrupes youngi . 91 Soil Movement by Other Animals . ... 95 Effects of Mixing on Soil Properties 98

APPENDICES

I SCIENTIFIC NAMES OF SPECIES CITED . . 102

II LOCATION AND PARTIAL CHARACTERIZATION
OF THE PAOLA SERIES PROFILES EXAMINED
IN THIS STUDY. ........ ..... 104

III DETERMINATION OF ORGANIC MATTER BY THREE STANDARD OXIDATION PROCEDURES . . 105

IV LOCATIONS OF 15 PAIRED PLOTS (SAMPLE
POPULATION II) AND 60 ADDITIONAL SITES
SAMPLED FOR BIOGENIC OPAL (SAMPLE
POPULATION III) .... ........ 108

V SUMMARY OF CHEMICAL AND PHYSICAL
CHARACTERISTICS OF PAIRED LONGLEAF
PINE AND SAND PINE BOUNDARY PLOTS ..... 114

VI BIOGENIC OPAL CONTENTS OF 60 SOILS FROM SAMPLE POPULATION III ..... . 119

LITERATURE CITED .... .... ......... . 120

BIOGRAPHICAL SKETCH ....... . . . . 127











v














LIST OF TABLES

Table Page

I-i Woody plants on sand pine sites with thick and thin scrubs . . . . 9

I-2 Woody plants on longleaf pinewiregrass and longleaf pine-turkey oak
sites . . . . . . . . . 11

I-3 Summary of ANOVA of rye yields from 0-18 cm depths of paired longleaf and
sand pine plots ..... .. ... ... 33

I-4 Textural characteristics of the uppermost uniform soil layers of 5 m
profiles from 15 pairs of longleaf and
sand pine plots . .......... . 41

I-5 Profile features or layers >25 cm thick occurring between 200 and 500 cm in 15
pairs of longleaf and sand pine plots . 42

I-6 Weighted average concentrations of extractable nutrients for two depths in
paired longleaf and sand pine plots . . 43

I-7 Description of a soil profile with loamy lamellae, cemented-sand fragments, and fine-textured subsoil under longleaf
pine-wiregrass .... . .. ..... 48

I-8 Opal contents of mature foliage of common plants of the longleaf and sand
pine communities .... ....... . 51

I-9 Two-year accumulations of grass and litter on five longleaf pine-wiregrass
sites, with estimated annual opal input 54

I-10 Opal content, distribution, and abundance of diagnostic forms in soils on
10 paired longleaf and sand pine boundary plots ...... . . .. . 65







vi










Table Page

I-11 Growth characteristics of old longleaf pines growing outside island
boundaries ......... . . . ... 75

1-12 Geographical and archeological settings of nine longleaf pine islands . . 77

II-1 Selected characteristics of four
vegetation categories: sand pine
with thick and thin scrub; longleaf
pine with thick and thin grass ...... 89

II-2 Average number of mounds and total
amount of soil deposited annually by
Peltotrupes beetles and pocket gophers . 96

II-3 Extractable element concentrations in
Peltotrupes beetle mounds compared with
adjacent 0-10 cm soil layers ...... . 99


































vii














LIST OF FIGURES

Figure Page

I-i Map of the Ocala National Forest, Florida.
Study area is located north of State
Highway 40 ............. .... 5

I-2 Soil catena diagram showing association among the Astatula and Paola series, and
wet Spodosols and Inceptisols ...... 18

I-3 Three general types of soil profiles with bleached surface (E) horizons under
sand pine . . . ... . . . 20

I-4 Variation in thickness and color of the A-horizon of the Astatula series, dark
surface phase, under longleaf pine .... 24

I-5 Mean organic matter contents of soil from paired longleaf and sand pine plots 27

I-6 Relationship between Munsell color value and organic matter contents of the 0-10, 10-20, and 20-30 cm depths of soil from
paired longleaf and sand pine plots .... 29

I-7 Effect of finely-ground (<0.05 mm) charcoal on soil color . . . . . . 31

I-8 Relationship between rye yield and extractable native P on paired longleaf
and sand pine 0-18 cm soil layers. All
soils received the equivalent of
20 kg/ha N . . . . . . . . 35

I-9 Profile diagrams illustrating the variability in continuity, depth, and thickness of deep soil horizons along a
longleaf-sand pine boundary ....... 39

I-10 Weighted average concentrations of extractable Ca + Mg and P for the 5 m depth
of 70 longleaf and sand pine sites both near
to and remote from boundaries (Sample
Population I) .. .... .. . . 47




viii










Figure Page

I-il Total opal contents of the 0 to 60 cm soil depth of paired longleaf and sand
pine boundary plots (see also Table
I-10) . . . . . . . . .. 57

1-12 Relationship between organic matter and opal concentrations in 10 cm increments of the 0-60 cm soil depths from
10 paired longleaf and sand pine plots 59

1-13 Comparative distributions of organic matter and opal with depth on paired
boundary plots . . . . . . . 62

1-14 Schematic patterns of biogenic opal accumulation (mt/ha/60 cm) in the vicinity
of four longleaf pine islands . . . . 68

II-1 Burrow of Peltotrupes youngi ... ... 87

II-2 Comparison of the number of beetle
mounds counted on twenty-one 300 m2
plots in 1981 and 1982. ..... . . 94






























ix














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


THE LONGLEAF PINE ISLANDS
OF THE OCALA NATIONAL FOREST, FLORIDA: A SOIL STUDY

by

Paul John Kalisz

December 1982

Chairman: Dr. Earl L. Stone Major Department: Soil Science

Two unlike forest communities co-exist on deep sands of the Ocala National Forest, Florida. Longleaf pinewiregrass-turkey oak (Pinus palustris-Aristida strictaQuercus laevis) occurs as isolated "islands," 60 to 4000 ha in area, in a matrix of sand pine-scrub (Pinus clausa-Quercus spp.). Striking contrasts in physiognomy and species composition, and sharp, stable boundaries, led to a belief that soil differences determined vegetation boundaries.

Examination of soils to a 5 m depth at 130 locations revealed no consistent differences in profile morphology, particle size distribution, or available nutrients by chemical analysis and bioassay. Thus,






x










the hypothesis of causal soil differences under the two communities was not sustained.

Differences in surface horizon (A, E) color were ascribed to additions of fine charcoal and to soilmixing by animals. Mixing, notably by scarab beetles (Peltotrupes youngi) and pocket gophers (Geomys pinetus), was much greater under longleaf than under sand pine.

Biogenic opal extracted from soils (0-60 cm) at 75 Locations provided evidence of vegetative history. Isolines of total opal mass were concentrically patterned around lonqleaf islands. This could be attributed to fluctuations in the sizes of islands. Opal morphology, and known vegetation changes, suggested that such fluctuations had occurred episodically over the past 5000 years.

Three lines of evidence led to the hypothesis that longleaf islands owe their existence to burning by early man: 1) The longleaf pine community is maintained only by ground fires at 1-3 year intervals. The incidence of lightning fires on the small islands is too low to ensure this regularity of burning. 2) Present islands are located adjacent to permanent sources of water, and often include areas of productive soils. 3) Man has occupied the region at least since 4000 B.C. Significant archeological remains are associated with longleaf islands, but not with the surrounding sand pine-scrub.



xi










Thus it is proposed that early man was attracted to favorable features found near present islands, and, by frequently burning, created or maintained an environment favorable to the longleaf pine community.














































xii














CHAPTER I
ORIGIN AND STABILITY OF THE LONGLEAF PINE ISLANDS

Introduction

The extensive range of longleaf pine (Pinus palustris)

overlaps the more restricted range of sand pine (Pinus

clausa) along the central ridge of peninsular Florida.

Here, characteristic communities of the two species

intermingle, separated by boundaries that are unrelated

to topography. The earliest descriptions emphasized the

contrasts in physiognomy and species composition, and

the sharpness of the contact between these communities

(Vignoles, 1823; Nash, 1895; Whitney, 1898). The rich

herbaceous flora of the longleaf parklands ("high pine

land") contrasted with the woody thicket ("scrub") under

sand pine:

It is an impressive sight to stand at the border
line between the scrub and the high pine land and notice the difference in the character of
the vegetation. The high pine land is open, the
trees are large and vigorous, and the ground
is covered with a crop of grass which gives very
good grazing for cattle. . These conditions stop abruptly at the edge of the scrub.
The boundary between the high pine land and
the scrub can be located without trouble within
a few feet. . In the scrub there is a
dense growth of scrub oaks and low bushes
and plants . . No grass is found, and only
the most hardy desert plants grow. When pines
grow it is the dwarf spruce pine {sand pine}
and not the long-leaf pine, while on the other





1








2

hand the spruce pine is not found across the
border in the high pine lands proper. (Whitney,
1898, p. 14-15.)

These floras, and the abruptness and apparent stability of their boundaries, have since been described in detail (Harper, 1914a, 1915, 1921; Mulvania, 1931; Webber, 1935; Kurz, 1942; Laessle, 1958, 1968; Mohlenbrock, 1976).

From the beginning, attempts were made to account

for the marked differences in native growth. The central role played by fire in the ecology of both longleaf and sand pine was recognized: frequent ground fires maintained the longleaf pine community, whereas more violent fires at longer intervals killed and rejuvenated sand pine stands (Nash, 1895; Harper, 1914b;Webber, 1935). Fire, however, was not explicitly considered as a factor in the origin and long-term stability of the two communities, and the possible role of prehistoric fire was unmentioned. Some writers concluded that climate, topography, and soil did not account for the observed vegetation patterns (Whitney, 1898; Sellards, 1912; Webber, 1935). Nevertheless, almost by default, the idea emerged that community boundaries were determined by soil factors such as water-holding capacity (Mulvania, 1931; Kurz, 1942), and contents of organic matter (Kurz, 1942) and nutrients (Laessle, 1958). In particular, the thesis that the sand pine community is characteristic of especially nutrient-poor soils (Laessle, 1958) has persisted until the present (Christensen, 1981).








3

The present study was undertaken to examine the

possible role of soil differences as factors accounting for the juxtaposition of the longleaf and sand pine communities on the Ocala National Forest in east-central Florida (Fig. I-1). Preliminary examination of substrates failed to reveal such differences. A systematic study was then designed to fully characterize these soils, including features that might indicate vegetative history. These findings were integrated with available ecological, archeological, and geographical information for a better understanding of the origin and stability of these communities.

Study Area

Location and Climate

This study was conducted on the Lake George Ranger District located in the northern portion of the Ocala National Forest (Fig. I-1). The climate is warm and humid. Annual precipitation is highly variable but averages about 1300 mm, with over 50% of the total between June and September (Aydelott, 1966). Average daily maximum and minimum temperatures are 320C and 200C for the April to October period, and 230C and 11C for November to March (Aydelott, 1966).

Geology

Brooks (1972) has given a generalized account of

the geology of the forest, but the area is geologically complex and many details are not known.

































Figure I-1. Map of the Ocala National Forest, Florida.
Study area is located north of State Highway 40.




















































I t






4.,

















aLt


-~f








6

Surficial deposits are generally sands. In the

western part of the study area, surface sands of varying thickness overlie the stratified sand, gravel, and kaolinitic clays of the "Citronelle Formation." This formation is continuous throughout the central ridge of Florida over a distance of about 240 km (Pirkle et al., 1963). To the east, sands are locally underlain by discontinuous or irregular clay layers, sometimes associated with stratified sand and gravelly sand. The entire region is underlain by Ocala Limestone, but at such a depth that none of the soil profiles examined were calcareous.

Elevations range from 49 m MSL in the northern part of the forest, to about 2 m along the St. Johns River. Surface drainage networks are absent, and the landscape is dominated by closed depressions. Topography is rolling, with varied landforms that include dune-like undulations and steep-sided sink holes.

Land surfaces above 30 m MSL have been above sea level during the entire Pleistocene (Alt and Brooks, 1965); hence, landforms and sediments consist of an as yet undeciphered mixture of old and young elements. These landforms have been shaped by marine, karst, and aeolian processes that operated episodically in the past in conjunction with shifts in the regional climate, and with fluctuations in sea and ground water levels.








7


Soils

The most common soils on the study area are wellto excessively-drained Entisols. These have less than 5% silt plus clay in the upper profile, and are classified in the hyperthermic, uncoated families of Spodic (Paola series) and Typic (Astatula series) Quartzipsamments (Aydelott et al., 1975).

Well-drained Ultisols also occur as small inclusions where fine-textured layers are within 2 m of the surface. These soils are taxadjuncts to the sandy, siliceous, thermic family of Psammentic Paleudults (Eustis series) (Aydelott et al., 1975).

All soils are developed in parent materials devoid of primary minerals and consisting of quartz sand with small contents of iron and titanium heavy minerals. Clay-sized particles are primarily quartz, kaolinite, interlayered minerals, and lesser amounts of gibbsite (Carlisle et al., 1978).

Vegetation

Sand and longleaf pines occupy approximately 100,000 and 30,000 ha, respectively, of well-drained soils on the forest (Aydelott et al., 1975). Longleaf pine occurs around the periphery of the southern part of the forest in the lake region, and as isolated stands in the northern part (Fig. I-1). Traditionally, these isolated stands have been called "islands" in reference to their contrast








8

to the surrounding sea of sand pine-scrub, or, in previous times, of scrub alone. There are at least nine islands which range in size from 60 to 4000 ha. All lie within the area that is north of the southern edge of Lake George, and bounded on the west, north, and east by the Oklawaha and St. Johns Rivers (Fig. I-1). These islands and their surroundings are the subjects of this study.

Sand pine-scrub occupies the center of the forest

as a SSE-trending strip about 60 km long and 10 to 20 km wide. This is the largest block of sand pine known. The Oklawaha and St. Johns Rivers, and the extensive wetlands and lakes to the south (Fig. I-1) isolate this unique forest, and have served as firebreaks against all but the greatest conflagrations arising outside.

"Scrub" refers to the thicket of evergreen shrubs, small trees, and dwarf palms that compose the understory of sand pine, and dominate in its absence. Height and density of scrub vary, depending on site conditions and age. The major species are myrtle oak (Quercus myrtifolia), Chapman's oak (Q. chapmanii), sand live oak (Q. geminata), and crookedwood (Lyonia ferruginea) (Table I-1), along with scrub palm (Sabal etonia), and saw palmetto (Serenoa repens). Grasses and forbs are virtually absent from scrub, except after disturbance.

Under a regime of frequent fire, longleaf pine grows as an open parkland with a groundcover of wiregrass










Table I-1. Woody plants on sand pine sites with thick and thin scrubs. All stands
were even-aged, 40 to 50 years old (n=5 sites for each; stems >2 cm dbh
counted on three 0.033 ha plots at each site).



Occurrence Density' Basal Area% (no. of plots) (stems/ha) (m2/ha)
Species thick thin thick thin thick thin Pinus clausa 5 5 520 848 17.7 18.5 Lyonia ferruginea 4 2 1028 515 1.2 0.7 Quercus myrtifolia 5 4 700 65 1.0 <0.1 Q. chapmanii 5 2 274 55 0.4 <0.1 Q. geminata 4 3 210 43 0.3 <0.1 Q. laevis 2 5 20 60 0.1 0.2 Ilex opaca 1 0 340 0 0.9 0 Average (mean S.D., n=5) 2650 451 1228 329 20.8 4.2 19.3 2.0



tAverages for number of plots shown in "Occurrence" column.








10

(Aristida stricta) and a diverse herbaceous flora. The latter includes numerous members of the Fabaceae, Compositae, and Euphorbiaceae. Woody plants other than pine are not prominent on frequently burned areas (LLP-WG type, Table 1-2), although gopher apple (Licania michauxii), redroot (Ceanothus microphyllus), persimmon (Diospyros virginiana), pawpaw (Asimina spp.), and oak (chiefly Q. laevis and Q. incana) are widely distributed.

Sites from which longleaf pine has been removed

without regeneration are often dominated by turkey oak (Q. laevis)(LLP-TO type, Table 1-2). The abundance and diversity of the herbaceous flora are much reduced.

The longleaf and sand pine communities both depend on fire for their perpetuation, but the nature of the dependence differs markedly (Harper, 1914b; Webber, 1935; Christensen, 1981). Sand pine, with its thin bark, and fine twigs and needles, is easily killed or damaged by fire. Fire, however, opens the closed cones characteristic of the Ocala sand pine, kills the scrub to ground level, and prepares a suitable seed bed. Thus, sand pine is generally believed to require fire at intervals of 20 to 70 years in order to successfully regenerate. Fires are not easily started in sand pine stands except under dry conditions, then, once ignited, they often burn cataclysmically (Webber, 1935; Cooper, 1973; Hough, 1973).

Longleaf pine, on the other hand, is superbly adapted to fire (Chapman, 1932; Wahlenberg, 1946). This tree














Table 1-2. Woody plants on longleaf pine-wiregrass (LLP-WG) and longleaf pineturkey oak (LLP-TO) sites. Grass weights were 1.4 0.5 and 0.2 0.0
mt/ha (mean S.D.) on LLP-WG and LLP-TO sites, respectively (n=5 sites
for each; stems >2 cm dbh counted on 0.1 ha area at each site).



Occurrence Density* Basal Area' (no. of plots) (stems/ha) (m2/ha) Species LLP-WG LLP-TO LLP-WG LLP-TO LLP-WG LLP-TO Pinus palustris 5 5 268 60 10.4 3.3 P. clausa 0 2 0 140 0 3.5 Quercus laevis 3 5 13 692 0.1 7.6 Q. incana 0 2 0 20 0 0.7 Q. geminata 0 3 0 20 0 0.1


Average (mean S.D., n=5) 279 183 838 354 10.6 3.1 12.7 2.4



tAverages for number of plots shown in "Occurrence" column.








12

requires ground fires at intervals of one to three years in order to prevent encroachment of less fire-resistant competitors. Without fire to eliminate competition and prepare a seedbed, longleaf pine regenerates poorly (Chapman, 1932; Wahlenberg, 1946). Likewise, without fire, the characteristic herbs are buried by litter accumulation or suppressed by invading shrubs or trees.

Methods

Field Methods

Three sample populations comprise the major basis of this investigation: I) Soil profiles were described and sampled to a depth of 5 m or more at 100 locations, both near to and remote from island boundaries. Some locations were selected after initial reconnaissance, others to replicate or expand on earlier observations. A 500 cm minimum depth was examined because sand pine roots extend to at least 400 cm, and longleaf pine roots to even greater depths.

II) Fifteen pairs of plots, additional to the above, were established on either side of longleaf pine-sand pine boundaries along six islands. The pairs were located at randomly-selected points along segments of boundaries where both contact and stand conditions indicated minimal disturbance; individual plots were sited 100 m to each side of the boundary. Soils were examined and sampled to the 5 m depth.








13

A bucket auger (7.5 cm diameter) was used to examine

profiles and collect samples from the above two populations. Uniform profiles were sampled in 50 cm increments, while those with more complex horizon sequences were sampled in smaller increments. Hence, a minimum of 10 samples per profile were collected.

At 10 of the 15 paired plots in Sample Population II, the upper 60 cm of soil was collected in 10 cm increments. Each increment consisted of a composite of 16 cores (2.5 cm diameter) collected in a 100 m2 area surrounding the bucket auger point.

At these same 10 paired plots, samples of the 0-18 cm layer were collected for a bioassay study. Each sample was a composite of four 400 cm2 blocks.

III) Composite samples from the 0-60 cm depth only were collected at 60 additional locations to provide information on the distribution of biogenic opal in soils. Each sample consisted of ten 2.5 cm diameter cores collected over a 100 m2 area.

Laboratory Analyses

Cations and phosphorus were extractedfrom soils with

0.05 N HC1 plus 0.025 N H2SO4 (double-acid procedure; Mitchell and Rhue, 1979). For sands lacking easilyweatherable minerals, extractable cations are approximately equal to exchangeable cations, and extractable P is an empirical index of availability (J. A. G. Fiskell, personal communication, 1982).








14

Organic carbon in soils was determined by the WalkleyBlack procedure (Jackson, 1958), and converted to organic matter using the conventional factor, 1.72.

Silt plus clay (fraction <0.05 mm) was estimated

gravimetrically after dispersion of the whole soil using Calgon, and separation by successive sedimentation and decantation. Sand was separated into standard USDA fractions using nested sieves.

Opal Extraction

Biogenic opal was extracted from whole soil samples

by a standard sink-float technique (Rovner, 1971). Organic matter was removed by dry-ashing at 4500C overnight. Opal was then separated from the heavier fraction by five successive purification steps in an ethanol-bromoform mixture of specific gravity 2.3. This was followed by further purification of the light isolate.

Opal was extracted from washed tissue samples by ignition and removal of soluble ash with HCI.

Isolated opal was examined for grain morphology and contamination with a 450x polarizing microscope. Nutrient Bioassay

Rye was grown in a greenhouse on twenty 0-18 cm samples from Sample Population II. The experiment was replicated with four fertilizer treatments: N20, N20P10, N20P10K20, and N40P10K20 (subscripts refer to the amounts added expressed as kg/ha). These small additions were








15

aimed not at maximizing yields, but at revealing differences within the natural range of nutrient supply available to shallow-rooted plants. Seeds were planted in December in pots holding 4 kg of soil, and soil water contents were maintained at approximately 10% (w/w). The plants were harvested 51 days later, at flowering. Dry-weight yields of above ground parts were compared by ANOVA.

Results and Discussion

Surface Soil Profiles

Morphology. The most striking difference between the soils of the longleaf pine community (LLP) and sand pine community (SP) is in the horizonation of the upper profile. The soil survey of the Ocala National Forest (Aydelott et al., 1975) shows the two primary soil series beneath SP to be Paola, with bleached (10YR 6/1-8/1) surface, or "E," horizons, and Astatula,with minimal surface horizon development. Soils on most LLP sites are also classified in the Astatula series, but are separated as a "dark surface phase" because of the presence of a dark (10YR 3/1-4/2) surface, or "A," horizon. The Astatula, Paola, and dark surface Astatula series occupy approximately 75,000, 15,000, and 30,000 ha, respectively, on the forest (Aydelott et al., 1975).

Twelve of the 15 SP paired plots (Sample Population II) occurred on Astatula soils, and three on Paola. All LLP plots occurred on dark surface Astatula soils. Both the








16

E-horizon of Paola soils and the A-horizon of LLP soils averaged about 20 cm thick on these plots, but varied from 5 to 50 cm over short distances.

The E-horizons of the Paola series had abrupt, generally smooth boundaries marked by thin, discontinuous layers of organic-stained sand. In contrast, the boundaries of LLP A-horizons were diffuse and highly irregular, with tongues, krotovinas, and bits of charcoal and organic matter occurring well below the main body of the horizon.

Throughout the forest, these three soils are interspersed in a complex pattern. Soils under SP can form a continuum between the Paola and Astatula series. A portion of such a continuum is illustrated in Fig. 1-2: the E-horizon of Profile 3 becomes progressively thinner and darker upslope. Over a distance of 50 m, with a rise of only 80 cm, the soil grades from a Paola with a thick E-horizon (Profile 3) to an Astatula with a thin A-horizon (Profile 1).

Three general types of Paola profiles were observed during this study (Fig. I-3; profile descriptions in Appendix II). The first type (Profile I, Fig. I-3) occurs as an intermediate member in a drainage sequence from Astatula to wet Spodosols, as shown in Fig. 1-2. The E-horizon is underlain by a brightly-colored zone of welldrained, brownish yellow sand (Profile I, Fig. I-3) that increases in thickness upslope. Below this layer, colors




















Figure 1-2. Soil catena diagram showing association among the Astatula (1) and
Paola (2, 3) series, and wet Spodosols (4) and Inceptisols (5).
Profiles 1, 2, and 3 are vegetated with sand pine, Profiles 4 and 5 with slash pine. Profiles 4 and 5 are 5 m apart; distance between
all others is 25 m. Elevational difference between Profiles 1 and 4 is 160 cm. Munsell color abbreviations are: bl = black; br = brown
or brownish; dk = dark; gr = gray; It = light; v = very; yell =
yellow. NW 1/4 NW 1/4 Sec. 5, T. 13 S., R. 26 E. Ocala National
Forest, Florida.







-dk gr
A I Gray S2Brownish yellow
2 \ Brown
'E gr Bh horizon
v3 Organic stains br yell" ....L- \ 3
l \ j Organic-cemented sand
N 100 .. E gr br yell \ Lt

100
4 5\ br A vdk \N.gr v dk .v pale E Lt r gr 200 br/ / 2\/dk0 / /' 'bl / /', b b/


200 v pole/ bbrr 100
200 dk br






















Figure 1-3. Three general types of soil profiles with bleached surface (E)
horizons under sand pine. Munsell color abbreviations are:
br = brown; dk = dark; gr = gray; It = light; red = reddish;
str = strong; yell = yellow or yellowish. Ocala National Forest,
Florida.








DEPTH M IT I
(cm)
Lt gr gr Lt gr
**'' Gray S.. Brownish yellow
100
br ellI. .* br yell Brown Sbr yell. *, Bh horizon 200- Clay
S. -* V Water table


300 It gr ,

f red
,yell / yell br 400 dk br /

yell br Z:
White
500-








21

are duller, and a distinct organic (Bh) horizon occurs near the water table. Such profiles commonly are found on lower slopes under SP, and along the margins of lakes and prairies under oaks, palms, and scrub.

The second type of Paola profile is well drained and brightly colored throughout (Profile II, Fig. 1-3). This type lacks Bh-horizons, but is distinguished by the presence of sandy loam to sandy clay loam subsoil layers at depths ranging from 200 to 350 cm. In most cases, these finer-textured layers clearly belong to the underlying "Citronelle Formation." Paola soils of this type occur as small isolated patches throughout the central part of the study area. The vegetation is SP, always with a thick scrub. The latter relationship suggests that the genesis of the E-horizon is in this case due to the greater biomass (Table I-1) and associated higher intensity of leaching under thick scrubs.

The third type of Paola profile lacks distinctive

horizonation below the E-horizon (Profile III, Fig. I-3). Diffuse organic stains and dull brown colors suggest, however, that Bh-horizons and water tables may have occurred in the past. This profile type has been examined in only a few locations in the eastern part of the study area. Its occurrence is not clearly related to present topography or elevation, but, since limestone occurs at relatively shallow depths in this part of the forest (Brooks, 1972),








22

the landscape has undoubtably been altered by subsidence (Alt and Brooks, 1965). These profiles possibly developed in the past as intermediate catena members similar to Profile 2, Fig. 1-2, and Profile I, Fig. 1-3.

These field observations suggest that soils now mapped as Paola (i.e., sandy soils with bleached surface layers) represent the convergence of developmental pathways. Landscape position and stability, and vegetative history and productivity are factors controlling development of bleached surface layers. In all cases, the dominant process is podzolization.

In contrast, LLP sites appear as typical grasslands, with frequent fires, a rich herbaceous flora, and an active soil-mixing fauna (see Chap. II). On such sites, podzolization is inhibited (McKee, 1982), and the dominant soil-forming process is the incorporation of surface detritus and the homogenization of the upper soil. Dark A-horizons develop under these conditions. As illustrated in Fig. 1-4, both the color and thickness of these surface layers vary greatly. On some sites, dark surface Astatula soils can actually grade into either of the two SP soils.

Differences in surface profile morphology on LLP

and SP sites reflect the dominance of different soil-forming processes. Such superficial differences, although striking, do not account for the occurrence of the two communities, nor indicate fundamentally different substrates beneath them.






















Figure 1-4. Variation in thickness and color of the A-horizon of the Astatula
series, dark surface phase, under longleaf pine. Based on 50 points
spaced at 10 m intervals. Riverside Island, Ocala National Forest,
Florida.







DISTANCE (m)
100 200 300 400 500


5 20

S40- 0 0 0 0 0* 0 0 0 0 0 0

60
Munsell Color
Dark gray to black (IOYR 4/1, 3/1, 3/2) j Dark grayish brown to dark brown (IOYR 4/2, 4/3, 3/3)

SYellowish brown (IO YR 5/4-5/8)







25

Organic matter and charcoal. Despite the dark surface beneath LLP, organic matter (OM1) contents and distribution in the upper profiles did not differ across the LLP-SP boundary in the paired plot comparison (Fig. 1-5). Total OM in the upper 60 cm depth ranged from 27.4 to 138.5 mt/ha (mean, 56.7) in LLP, and from 27.2 to 77.0 mt/ha (mean, 48.1) in SP. A power function approximately described distribution with depth in both soils (Fig. 1-5). Average concentrations decreased from 1.7% (range, 0.8 to 3.2%) in the 0-10 cm, to 0.2% (<0.1 to 0.8%) in the 50-60 cm depth.

As expected, soils with higher OM concentrations were generally darker on the Munsell color scale. Among soils with the same organic concentrations, however, LLP soils were consistently darker than SP soils (Fig. 1-6). This difference is due to the presence of finely-divided charcoal in LLP soils. Attempts to separate charcoal from organic-C by differential oxidation techniques yielded inconsistent results (procedures and results in Appendix III). This is due in part to the small quantities present, and to the influence of particle size, rather than total amount, on soil color. The effect of small amounts of fine charcoal on soil color is illustrated in Fig. 1-7. These results (Figs. 1-6, I-7) agree with earlier speculation (Nash, 1895; Webber, 1935) that the dark surfaces of LLP soils result primarily from the charcoal added by frequent





























Figure I-5. Mean organic matter contents of soil from
paired longleaf (LLP) and sand pine (SP)
plots (n=10; mean S.D.). The depth function of OM is Y = 163X-0.81 (r2 = 0.79) for
LLP, and Y = 160X-0-80 (r2 = 0.53) for SP,
where: Y = percent of total (0-60 cm) OM in a 10 cm increment; X = increment midpoint (n=60).






27


ORGANIC MATTER (mt/ha)
10 20 30
LLP
O -10 10-20 0 20-30 I I 03 30-40


40-50



50-60 r
























Figure I-6. Relationship between Munsell color value and organic matter contents
of the 0-10, 10-20, and 20-30 cm depths of soil from paired longleaf and sand pine plots.












A*

5 ..*!^* * *
SAND PINE
A AAA A * A LONGLEAF PINE

4 A Ak ***

SAA AA A *



A A AA A

2 A
Io 20 30 ORGANIC MATTER (%)
iI









ORGANIC MATTER (%)




















Figure 1-7. Effect of finely-ground (<0.05 mm) charcoal on soil color. Left to
right, natural longleaf pine soil with 1.7% organic matter; natural
sand pine soil with 1.7% organic matter; same sand pine soil with
0.25% charcoal added.




































I., r. r~lr 1~Sit~L~E~iS~AY~l-a







32

fires. All surface soils examined contained charcoal fragments, but darkening seems due to a finely-divided component produced by ground fires on LLP sites.

Fertility. Historical references to differences in crop yields between LLP and SP soils in the early settlement period (Whitney, 1898) prompted a bioassay of surface soils (0-18 cm) from paired plots (Sample Population II). The object was to determine if there were differences in nutrient availability important to the growth of shallowrooted plants, but undetected by standard chemical extraction procedures.

In this greenhouse study, yield of rye increased significantly (Table I-3) with each added element and with the level of nitrogen:

Yield (g/pot)
N20 N2010 N20P10K20 N40P10K20
LLP 1.5 2.1 2.7 3.9 SP 1.5 1.9 2.4 3.3


Yields from the pots receiving only N20 varied 12-fold, and were positively correlated with extractable native P (Fig. 1-8), but not with extractable Ca or Mg.

As Fig. I-8 implies, the effect of location on yield was highly significant (p=0.0001)(Table 1-3). The mean difference between the two vegetation types, however, was significant only at the 5% level (Table 1-3). This difference was due almost entirely to inclusion of two Paola







33
















Table 1-3. Summary of ANOVA of rye yields from 0-18 cm
depths of paired longleaf and sand pine plots
(10 pairs x 4 fertilizer treatments).



Significance Level (p)
All Paired Excluding Plots Paola Soils Comparisons (n=10) (n=8)

Among locations 0.0001 0.0001 Between vegetation types 0.0258t 0.6200 Among fertilizer treatments 0.0001 0.0001f Vegetation x fertilizer 0.5089 0.8723



tLongleaf pine > sand pine.

N40P 1K20 > N20P10K20 > N20P10 > N20-
































Figure I-8. Relationship between rye yield and extractable
native P on paired longleaf and sand pine
0-18 n soil layers. All soils received the
equivalent of 20 kg/ha N.








35






4.0
A






3.0






0.64
8 Yield=0.57 (p)
Sr2- 0.70
2.0- A
-J
L
CC A LLJ

*A



1.0
S* SAND PINE SOIL A LONGLEAF PINE SOIL

I*





0 5 10 15 20 25
EXTRACTABLE P (ppm)







36

soils in the comparison. These samples consisted entirely of the leached E-horizon, and gave the lowest yields, less than 1.1 g/pot as compared with the mean of 2.4 g/pot for all SP soils. Exclusion of these two plots (and their LLP pairs) from analysis (Table I-3) resulted in nearly identical mean yields for LLP and SP soils, 2.63 and 2.55 g/pot, respectively.

Thus these results reveal no consequential differences in surface soil fertility associated with the boundaries between LLP and SP. The exceptions are the Paola soils. Their low yields may account for some of the early reports (Whitney, 1898) that garden crops could not be successfully grown on SP soils.

The fertility status of LLP and SP surface soils

can also be viewed through comparison with Florida agricultural soils using a rating scheme (IFAS, 1981) of high

(H), medium (M), and low (L) for OM and extractable nutrients. The percentage distribution of the 20 paired surface layers into these categories is compared below with Rhue and Sartain's (1978) summary of cultivated soils: Distribution (%)
OM P K Mg
L M HH L M H L M H Agric. soils 89 10 <1 30 15 55 69 17 14 15 20 65 LLP/SP soils 90 10 0 70 25 5 90 10 0 100 0 0 Organic matter, P, and K distributions of agricultural soils are for Entisols only, whereas that of Mg is for a







37

variety of soils. Nitrogen contents are assumed to vary directly with OM.

Results of the bioassay indicate that there is no consistent difference in the productivity of LLP and SP surface soils (Table 1-3). The comparison of these LLP-SP soils to agricultural soils (text table above), most of which have been fertilized, suggests that the former are not especially infertile relative to other unamended forest soils. Both results are contrary to the conventional generalization that the SP community is an indicator of particularly nutrient-poor sites (Laessle, 1958; Christensen, 1981). Further chemical characterization of these soils is given later under "Deep Soil Profiles." Deep Soil Profiles

Morphology and texture. Substrate characteristics varied throughout the study area. Geological strata and deep soil horizons were seldom parallel to the present surface, nor consistently related to elevation or landscape position. As a result, occurrence of particular layers changed unpredictably over distances of tens of meters, as did their depth, thickness, and continuity (Fig. I-9).

Characteristics such as texture, depth to a water table, and occurrence of strongly contrasting textural strata (Hillel and Talpaz, 1977), loamy lamellae or clay horizons (Oliver, 1978) within rooting depth obviously




















Figure 1-9. Profile diagrams illustrating the variability in continuity, depth,
and thickness of deep soil horizons along a longleaf (LLP)-sand
pine (SP) boundary. Vertical scale indicates both relief and profile
depth. Inset shows plan-view; legend refers to Munsell colors.
NE 1/4 Sec. 25, T. 13 S., R. 26 E. Ocala National Forest, Florida.





DEPTH
SPI SP2 LLPI LLP2 (cm)


\ SP3
LLP3 S . -- -200
.. "" LLP4 LLP5


-400



<^ -600 LLLP


Brownish yellow sand 800 O White sand

L Brown sand N 000

Bh-horizon 4 3 2

Black A-horizon *4*3 I LLP ~I Gray clay .5
*2
I1 Organic stains *6 7... Water table







40

influence water availability and may affect the composition of natural vegetation. No consistent differences in such properties were found on the 15 paired plots straddling LLP-SP boundaries.

These profiles were characterized by texturallyuniform surface layers of fine and medium sand containing

2 to 5% silt plus clay (chiefly clay)(Table 1-4). Thickness of this layer varied from less than 1 to 5 m, but means and ranges were similar beneath both vegetations. The same was true of the textural properties.

Beneath the uniform surface layers, textural stratification was common, with layers ranging from very coarse sand and gravelly sand, to sandy clay loam. Neither the

occurrence nor depth of specific characteristics was related to LLP vs. SP types (Table I-5).

Chemical characteristics. Profiles were acid throughout, but pH values did not differ between vegetation types. Mean pH's were 4.7 and 5.0, respectively, in the 0-50 cm and 450-500 cm depths (n=30). The minimum pH was 4.5 in a surface horizon, and the maximum in a single subsoil was

6.1

The soil fertility status of the two communities was examined by using extractable base and P contents (Table 1-6). Potassium concentrations were uniformly below

0.01 me/100 g, and hence were not considered. The values given in Table I-6 for the 0-200 and 200-500 cm depth are







41

















Table 1-4. Textural characteristics of the uppermost
uniform soil layers of 5 m profiles from 15 pairs of longleaf and sand pine plots.
(Small amounts of very coarse, coarse, and
very fine sand also occurred in these layers.)



Sand Pine Longleaf Pine Characteristic Mean Range Mean Range

Thickness (cm) 275 70-500 275 80-500 Medium sand (0.25-0.50 mm)(%) 54 43-61 49 41-64 Fine sand (0.10-0.25 mm)(%) 37 26-56 40 19-64 Silt plus clay (<0.05 mm) (%) 3 2-4 3 2-5







42









Table 1-5. Profile features or layers >25 cm thick
occurring between 200 and 500 cm in 15 pairs
of longleaf (LLP) and sand pine (SP) plots.



Occurrence (no. of paired plots) Feature or Layer LLP Only SP Only Both

Layer with >60% fine sand 2 2 4 Finely-stratified sand 3 0 1 Loamy lamellae 1 0 2 Layer with 5 to 10% clay 2 3 0 Layer with >10% clay 2 0 1 Layer with >2% gravel 2 0 2 Layer with >2% cemented-sand 2 0 0
fragments

Organic layer (Bh horizon) 0 1 1 Water table 0 1 1







43













Table 1-6. Weighted average concentrations of extractable
nutrients for two depths in paired longleaf
(LLP) and sand pine (SP) plots. (* = difference between LLP and SP means significant at a=0.05.)



Concentration
0-200 cm 200-500 cm
Element LLP SP LLP SP All Sites (n=15)

Ca + Mg (me/100 g) 0.10 0.06 0.09 0.04 P (ppm) 7.8 3.8 9.1 9.9 Excluding LLP Sites with Layers Containing >10% Clay (n=13)

Ca + Mg (me/100 g) 0.08 0.06 0.05 0.04 P (ppm) 3.3 2.7 9.1 9.8







44

means weighted by horizon thickness and an average bulk density.

Neither total bases nor P contents of the 200-500 cm layer differed significantly between the two vegetation types. Although extractable base concentrations appear slight, the totals for this layer alone equal or exceed the amounts likely to be contained in mature stands:

0.1 me/100 g in the 200-500 cm depth approximates 1000 kg/ha Ca or 600 kg/ha Mg. Extractable P concentrations are surprisingly greater than might be expected, and represent

substantial reservoirs of this element for deep-rooted plants.

Extractable bases in the surface 200 cm layer were

significantly higher beneath LLP (Table 1-6). At two locations, however, a layer containing greater than 10% silt plus clay occurred below 300 cm under LLP but not SP (Table 1-5). The resulting large differences in Ca + Mg (me/100 g) are shown below:

0-200 cm 200-500 cm
Location LLP SP LLP SP Pats Island 0.25 0.06 0.31 0.04 Hughes Island 0.19 0.08 0.38 0.06 Excluding these two pairs from analysis indicates no significant difference in base contents between the two types (Table I-6).







45

Data from extensive study plots (Sample Population I) have identified a zone of relatively high P concentration extending through Pats Island (Fig. I-1) and for unknown distances into SP along the north and south boundaries. Hence exclusion of the Pats Island site from the comparison also reduces the large mean difference in P concentrations in the 0-200 cm layers (Table 1-6).

The preceding results from the paired plots (Sample Population II)(Table I-6) were borne out by data from the more widely distributed samples (Sample Population I). Weighted average concentrations of P, and Ca + Mg for 70 such locations are shown in Fig. I-10. Phosphorus values cluster between 1 and 30 ppm with no apparent relation to vegetation type. For the most part, base contents range between 0.02 and 0.1 me/100 g, again independent of vegetation.

Seven profiles from LLP had average base contents of 0.2 to 0.6 me/100 g (Fig. I-10). All seven were characterized by reddish loamy lamellae or subsoil horizons, somewhat finer sand textures, and sporadic occurrence of cemented-sand fragments. A representative profile of this type is described in Table 1-7. Such soils occurred as scattered inclusions on LLP sites, but were much less common under SP. Some of these areas, with loamy lamellae within 200 cm of the surface, had been mapped as the Eustis and a banded substratum phase of the Astatula series (Aydellot et al., 1975).
































Figure I-10. Weighted average concentrations of extractable Ca + Mg and P for the 5 m depth of
70 longleaf and sand pine sites both near
to and remote from boundaries (Sample
Population I).






47


0.6 -A

SAND PINE A LONGLEAF PINE
0.5





4 0.4 #
0
0
N

E 0.3 A A


+
( 0.2 -A




0.1 A
*A AA *
A& 0
A* A


I I I I
0 10 20 30 40 P (ppm)







48


Table 1-7. Description of a soil profile with loamy
lamellae, cemented-sand fragments, and finetextured subsoil under longleaf pine-wiregrass.
SE 1/4 Sec. 17, T. 12 S., R. 25 E., Ocala
National Forest, Florida. (This profile corresponds to 0.4 me/100 g Ca + Mg, and 2.2 ppm P
on Fig. I-10.)



Depth (cm) Description

0-20 Dark grayish brown (10YR 4/2) sand. 20-30 Brown (10YR 5/3) sand. 30-60 Dark grayish brown (10YR 4/2) sand. 60-130 Pale brown (10YR 6/3) sand. 130-160 Very pale brown (10YR 7/3) sand, with thin,
indistinct lamellae.

160-200 Very pale brown (10YR 7/3) sand, with distinct,
strong brown (7.5YR 4/6) lamellae up to 5 cm
thick and occupying 15% of the horizon.

200-300 Very pale brown (10YR 8/3) sand, with thin,
indistinct lamellae, and few coarse cementedsand fragments.

300-320 White (10YR 8/2) sand. 320-370 Yellow (10YR 7/8) loamy sand, with a faint
network of very thin lamellae.

370-400 Yellowish brown (10YR 5/8) loamy sand to sandy
loam, with few white (10YR 8/1) mottles.

400-450 Yellowish red (5YR 5/8) sandy loam, with white
(10YR 8/1) and reddish brown (5YR 5/4) mottles. 450-500 As above, but sandy loam to sandy clay loam. 500-600 Equal parts white (10YR 8/1) and reddish yellow
(5YR 6/8) sandy clay loam.







49

Profiles of this type seem to be the most productive soils for pine on the study area. The site index (at age 50, converted to meters from USDA, 1929) of six dominant longleaf pines on two such soils averaged 24.8 0.9 m (mean + S.D.) as compared with 19.7 2.4 m for 14 trees at five locations without fine-textured layers. Age at breast height was 57 to 82 years in the first instance, and 51 to 60 years in the second. Higher productivity of "Eustis-type" soils probably arises more from their greater water storage capacity than from higher exchange capacity and exchangeable base content.

The close similarity in physical (Tables 1-4, I-5) and chemical (Table I-6; Fig. I-10) characteristics indicates a generally uniform substrate across vegetation boundaries. Where differences occurred, they were not consistently related to vegetation type. Opal

In other regions, phytoliths (plant opal bodies)

extracted from the soil have served as evidence for the occurrence of prairie vegetation in what is now forest, and vice versa (Witty and Knox, 1964; Wilding and Drees, 1968a). This is possible because of the greater contents and characteristic polyhedral shapes of opal in grasses. One might expect similar differences to occur between the scrub- and grass-dominated understories of sand pine and longleaf pine forests. If boundaries between these two







50

have indeed been stable over long periods, different quantities and morphological suites of opal should have accumulated in the two soils.

This possibility was tested by examination of

1) opal mass, morphology, and distribution in the 0-60 cm soil depth of the 10 paired boundary plots previously studied (Sample Population II)(Figs. 1-5, I-8); 2) opal mass and morphology in the 0-60 cm depth at 60 other locations (Sample Population III). These latter were selected to define patterns of opal accumulation in the vicinity of LLP islands. Additionally, opal content and morphology of common plants of the two communities were examined.

Content and morphology of opal in plants. Of the five

species with highest basal areas on SP sites (Table I-1) only Q. geminata had foliage opal contents greater than 0.5% (Table 1-8). Its phytoliths consisted primarily of curved needles as long as 80 pm, together with cup assemblages (sensu Wilding et al., 1977), and smoothspheroids up to 20 um in diameter. Opal contents of other oaks, sand pine, and Lyonia (Table I-8) consisted mostly of unidentifiable fragments, with some rods (20-40 um long), cup assemblages, and spheroids (<10 pm diameter).

Foliage opal contents of Sabal etonia and Serenoa

repens averaged over 3% (Table 1-8). Sabal opal occurred chiefly as unidentifiable fragments with some spheroids averaging 2.7 + 0.7 um in diameter (details given on p. 63).








51







Table 1-8. Opal contents of mature foliage of common
plants of the longleaf and sandpine communities.



Species Opal (%)

Sand Pine Community

Pinus clausa (4) 0.43 0.08 Lyonia ferruginea (1) 0.29 Quercus myrtifolia (4) 0.44 0.10 Q. chapmanii (4) 0.38 0.10 Q. geminata (3) 1.33 0.48 Sabal etonia (3) 3.14 0.84 Serenoa repens (3) 3.67 1.06

Longleaf Pine Community

Pinus palustris (3) 1.09 0.26 Quercus laevis (1) 0.39 Aristida stricta (3) 2.48 0.20




'Number in parenthesis represents collection sites. Composite samples of foliage from at leat 10 plants at each site were analysed in duplicate. tMean S.D.







52

Approximately 30% of Sabal spheroids were smooth, and the remainder were "pollen-like," with surfaces that were either roughened or studded with protuberances. Serenoa opal consisted of silicified guard cells and spheroids imbedded in fragile opaline sheets or ribbons. Spheroids averaged

5.4 2.0 pm in diameter; about 10% were smooth, the remainder pollen-like.

The concentration of opal in wiregrass was 2.5%

(Table I-8), which is about average for grasses. These phytoliths were chiefly solid forms including rods, guard cells,and dumbbell shapes. The latter forms ranged from 10 to 30 um long, and 5 to 12 jm wide.

Surprisingly, opal concentration in longleaf pine

needles was 1.1% (Table I-8). This is over five times the amounts commonly reported for the genus (Miles and Singleton, 1975; Klein and Geis, 1978). Hence, unlike many species of forest trees, longleaf litter adds significant quantities of opal to the soil. Longleaf pine phytoliths were chiefly irregularly-rounded and, less commonly, elongate solids up to 20 pm in largest dimension. Rods, 20 to 40 pm long and

5 pm wide, were also common, with smaller numbers of cup assemblages and fragile encrustations.

Opal accumulations in longleaf and sand pine soils.

Opal accumulation rates are the net result of biogenic input minus weathering losses from the soil. Accumulation rates beneath LLP and SP vegetations are not known. The







53

estimated opal input on islands is in the vicinity of 30 to 40 kg/ha/yr, based on limited sampling (Table 1-9). Comparable estimates for the SP type are not available. Order of magnitude estimates can be derived from measures of total mass of foliage within 1.5 m of the ground (Harlow et al., 1980), and the opal concentrations of scrub species (Table 1-8). Foliage mass within 1.5 m of the soil surface in SP stands from 1 to 60+ years old ranged from 800 to 2300 kg/ha; the average for stands older than 25 years was about 1000 kg/ha. Foliage of sand pine and that of the upper crowns of Lyonia and taller Oaks is not included. Tall shrubs are sparse, however, in the SP-thin scrub type (Table I-1) which predominates on the study area. Thus, although the relationship of total scrub foliage mass to annual litter fall is unknown, the latter can scarcely exceed the 2500 kg/ha/yr rate of LLP sites (Table 1-9), and probably is much less.

Opal contents of sand pine and scrub species, apart from the two palms, are much lower than in longleaf pine and wiregrass (TablesI-8, 1-9). Annual foliage productions, hence opal inputs, of the palms are unknown. Areas where palms are presently most abundant have low total biomass (thin scrubs, Table I-1) and low contents of opal in the soil. The ubiquity of palm-like spheroids in soils suggests that these species were more widely distributed and perhaps more abundant in the past. At present, however, their







54
















Table 1-9. Two-year accumulations of grass and litter on
five longleaf pine-wiregrass sites, with
estimated annual opal input. Grass includes
all attached wiregrass foliage; litter is chiefly longleaf needles with some grass.
(n=5, except for grass opal %, where n=3).




Annual
Massi Opal Opal Input
(kg/ha) (%) (kg/ha/yr)

Grass 1400 500 2.48 0.20 17

Litter 3600 1400 2.16 0.57 19


36




Two-year accumulations.







55

abundance is limited, and almost certainly total annual opal input in the SP community is much lower than in LLP.

Weathering rates of opal in the humid, warm, excessivelydrained soils of the study area are open to conjecture. The increased solubility of amorphous silica with temperature (Wilding et al., 1977) should lead to more rapid losses than occur in northern climates. Solid forms of low surface area are more stable (Bartoli and Wilding, 1980) and hence accumulate. Such forms predominate in longleaf pine needles and wiregrass. In contrast, the distinctive thin needles of Q. geminata are seldom observed in soils. The thin opaline matrix of palm foliage is also short-lived, but spheroids persist, and palm-like spheroids are the most common forms in SP soils.

Thus, a greater accumulation of opal under the LLP

community probably results both from a greater stability of opal forms, and from a larger annual input.

Opal in soils of paired boundary plots.

(1) Mass. The total mass of biogenic opal ranged

from less than 1 to more than 10 mt/ha in the 0-60 cm depth (Fig. I-11). There was no correlation of the amounts found in the LLP and SP members of the same pair. Opal concentrations in the 0-10 cm layers were substantially higher under LLP (Fig. 1-12), and total amounts were greater under LLP at nine of the 10 locations. The differences between LLP and SP were not consistent, however, ranging





















Figure I-11. Total opal contents of the 0 to 60 cm soil depth of paired longleaf
(LLP) and sand pine (SP) boundary plots (see also Table I-10).
















10
0 SAND PINE 8] LONGLEAF PINE

E
0 (D 6
C

E 4
-J


2



II 7 13 12 15 9 8 10 14 6 PAIRED PLOT
































Figure 1-12. Relationship between organic matter and
opal concentrations in 10 cm increments
of the 0-60 cm soil depths from 10 paired
longleaf and sand pine plots. Open
symbols designate the 0-10 cm increments.








59







.28



.18



.16

A Longleaf pine

.14 Sand pine A a A A .12


10
..J

O
.08 A

.08 A A







A A
A A
*AAe o o



S*o o


0.5 1.0 1.5 2.0 2.5 3.0 ORGANIC MATTER (%)







60

from 200 to 9000 kg/ha/60 cm (Fig. I-11).

(2) Distribution with depth. Opal contents decreased

with soil depth in both communities (Fig. 1-13). Under LLP, the distribution of opal was a power function of depth, and approximated that of OM. Opal was distributed more erratically in SP soils. As compared with either the distribution of organic matter, or with that of opal under LLP, a smaller percentage of the total opal in SP soil occurred above 20 cm (Fig. 1-13).

The diffuse relationships between amounts of opal and OM in individual layers are revealed by a scatter diagram (Fig. 1-12). Opal increased as OM increased in LLP soils, whereas the relationship was poor under SP.

(3) Morphology. Two types of biogenic opal, dumbbellshaped phytoliths and diatom frustules, were used as indicators of the LLP community. Dumbbells are diagnostic for Panicoid grasses (Twiss et al., 1969), including wiregrass. Soil-inhabiting diatoms characteristically inhabit open LLP stands, but not the shady scrub (Smith, 1944; Patrick, 1977), although the latter may have been more open prior to effective fire control. Thus it is not surprising that both of these forms accumulate in soils on the LLP side of stable boundaries.

Opal assemblages from the two communities at the 10

boundary locations differed in proportion of characteristic forms:






























Figure 1-13. Comparative distributions of organic matter
and opal with depth on paired boundary plots.
Depth functions for opal are Y = 108X-0-66 (r = 0.52) for longleaf pine soils (LLP), and Y = 39X-0.33 (r2 = 0.15) for sand pine soils (SP). Y = % of total (0-60 cm) opal
in a 10 cm increment; X = increment midpoint;
(n=60)(compare with Figure I-5).







62





DISTRIBUTION (%) 10 20 30 40 50


0 -10



10-20 I-

z 20-30 -O
/ : - LLP OPAL S/....... SP OPAL

z I
-30-40 / Q.


40-50



5060
50-60








63

Mean Percent of L5 pm Grains (n=20,000) LLP SP

Dumbbells 1.3 0.2 Diatoms 0.5 0.2 Spheroids 10.9 20.7 (* = significant at a=0.05)


Dumbbells were six times as common in LLP soils. Diatoms, and other solid forms identifiable as grass and longleaf needle phytoliths (see "Content and morphology of opal in plants") were common in LLP soils, but less frequent in SP soils.

Opal from SP soils consisted primarily of indistinct fragments and spheroidal shapes (see text table above). Some spheroids were identical in size and ornamentation to those from scrub palm and saw palmetto (See "Content and morphology of opal in plants"). Others were substantially larger than spheroids in these palms: Diameter of Spheroid (pm)

Mean S.D. Range

Scrub Palm (n=100) 2.7 0.7 1-4 Saw Palmetto (n=100) 5.4 + 2.0 1-11 SP soil (n=150) 8.5 3.7 1-20


The origin of the larger spheroids is unknown. Such forms were either absent or present in low numbers in the plants listed in Tables I-1 and I-2 (see "Content and morphology







64

of opal in plants"); nor were they found in bracken (Pteridium aquilinum), beargrass (Yucca filamentosa), dogfennel (Eupatorium sp.), cabbage palm (Sabal palmetto), or Andropogon grasses, all of which occur in the area.

Fragmented sponge spicules were widely but sparsely

distributed in both LLP and SP soils. Their occurrence was not related to proximity to lakes or wet prairies.

(4) Discussion. The bulk of the total biogenic opal

in these soils occurs in the upper 60 cm depth. Concentrations were generally below 0.02% in the 50-60 cm increments.

No opal was found in or above illuvial layers occurring between 200 and 600 cm, including Bh-horizons (n=5), loamy lamellae (n=2), and the upper parts of clay layers (n=3). This lack of evidence for downward migration agrees with observations in Illinois soils (Jones and Beavers, 1964) but not with the opal accumulations above some clay layers in Australia (Hallsworth and Waring, 1964).

Total opal mass in soils from the boundary plots

was not clearly related to present vegetation type (Fig. I11). Distribution with depth (Fig. 1-13) and morphology (see text table, p. 63) differed by type when averaged over all locations. When individual pairs of LLP and SP boundary plots are compared, however, such differences are not consistent (Table I-10). At some locations (e.g., Pair No. 6, Table I-10), opal mass and occurrence of diagnostic forms are clearly different in the two soils, whereas at others, the values are similar.








Table I-10. Opal content, distribution, and abundance of diagnostic forms in soils
on ten paired longleaf (LLP) and sand pine (SP) boundary plots.



Percent of Total Above:
Pair No. Opal Mass 10 cm 20 cm 30 cm DumbbellsT Diatoms and Island LLP SP LLP SP LLP SP LLP SP LLP SP (mt/ha/60 cm) %) (%)

6 Pats 10.6 1.5 31 32 55 39 75 49 1.6 <0.1 0.4 0.1 7 Norwalk 2.5 0.7 35 37 62 37 81 61 2.3 <0.1 1.6 0.2 8 Salt Springs 3.5 3.1 47 20 63 38 72 48 0.5 0.4 0.2 0.3

9 Kerr 3.3 3.1 30 20 42 38 51 58 1.5 0.2 0.7 <0.1 10 Riverside 4.7 1.3 37 28 55 49 72 58 1.3 0.3 0.7 0.1 11 Riverside 1.4 1.5 27 25 47 43 69 63 0.8 0.3 0.2 0.1 12 Salt Springs 2.8 2.3 40 27 54 44 71 58 1.2 0.4 0.6 0.4 13 Norwalk 2.6 1.0 48 62 70 71 82 71 1.5 <0.1 0.3 0.3 14 Hughes 5.3 4.4 30 22 48 38 66 53 1.4 0.5 0.8 0.3 15 Riverside 3.3 2.5 23 20 36 36 55 55 1.6 0.2 0.2 0.1


tPercent of >5 um grains, n=2000.








66

These large inconsistencies would not be expected if the abrupt boundaries observed in the recent past (Nash, 1895; Whitney, 1898) had in fact been stable over long periods of time. Hence these data lead to questions about the stability of LLP-SP contacts.

Opal patterning around longleaf pine islands.

(1) Mass, morphology, and patterning. Opal mass from the 60 additional sample sites in the vicinity of islands ranged from minima of less than 1 mt/ha/60 cm to maxima of 6.0 and 15.5 mt/ha/60 cm on SP and LLP sites, respectively (See Appendix VI).

Morphological differences between the two opal

assemblages were similar to those found on the boundary plots (see text table, p. 63), except that dumbbells and diatoms were virtually absent from SP sites that were distant from boundaries. Dumbbells were about 30 times greater, and diatoms 6 times greater in the >5 pm opal fraction from LLP than from SP locations. Dumbbells occurred in all LLP soils, including those now vegetated with turkey oak, and presently lacking grass. This demonstrates that the extensive areas of turkey oak (LLP-TO type, Table I-2) on this forest formerly supported longleaf pine parklands with abundant grass (LLP-WG type, Table I-2).

Intensive sampling in portions of the study area revealed a distinct patterning of opal mass around LLP islands (Fig. 1-14). The zones of highest opal contents were always





















Figure 1-14. Schematic patterns of biogenic opal accumulation (mt/ha/60 cm) in the
vicinity of four longleaf pine islands. Large points represent values
used in constructing isolines; small points, with associated weights, were not included in the pattern. Letters refer to anomolous values:
A, 4.6; B, 1.2; E, 1.8; F, 2.4 mt/ha/60 cm.

















SALT SPRINGS ISLAND






I2 A










2 3 4 1 4 43 I




DEL AN





RIVERSIDE LE ISLAND
4*21
88
535


2

HUGHES ISLAND PATS ISLAND
A E K ERR



KILOMETERS







69

located on islands, but the surrounding isolines did not conform to present island boundaries.

The opal isolines of Fig. 1-14 are based on relatively few points, and are more diagrammatic than definitive. Zones of high opal may actually be larger in area or more numerous, and isoline patterns may differ in detail. Nevertheless, evidence from the four most intensively sampled islands (Fig. 1-14), and from other islands sampled in less detail, indicates that concentration of opal in the vicinity of islands is general throughout the study area.

(2) Discussion. There are few plausible hypotheses

to account for this concentric zonation of opal. Topographic relationships and particle size distributions alone rule out explanations based on differential erosion and deposition. Sponge spicules, which have been used as indicators of aeolian deposits on uplands (Wilding and Drees, 1968b), were not concentrated in areas of high opal content. Moreover, the monotonic decrease of total opal with depth (Fig. 1-13) indicates accumulation in situ rather than a transported origin (Wilding et al., 1977).

Apparent differences in biomass productivity are evident throughout the area (Table I-3; Fig. 1-8, 1-10), and must influence the annual input of opal within vegetation types. Such current differences in productivity cannot account for the concentric patterns shown in Fig. 1-14. Three of the four zones of highest opal correspond to areas of the







70

relatively more productive "Eustis-like" soils (Table I-7). The fourth, on Pats Island, is underlain by soils exceptionally high in P and bases. There is no evidence of productivity gradients outward from these centers, however, that might result in concentric opal patterning. Moreover, relatively high opal contents also occur in soils that are apparently less productive than the four noted above.

The observed patterns of opal distribution (Fig. 1-14) are consistent with a hypothesis of shifting boundaries between communities with different rates of opal accumulation (Miles and Singleton, 1975). Biogenic opal is reported to persist in some Ohio soils for periods of up to 13,000 years (Wilding, 1967). The vegetation of the Ocala area has changed drastically in a much shorter time than this. A pollen profile from Mud Lake, on the western edge of the study area (Fig. I-1), indicates a shift from dominance by oaks, grass, and forbs between 8000 and 5000 B.P., to a preponderance of pine (species unknown) and disappearance of grass after 5000 B.P. (Watts, 1969). Hence, opal extracted from these soils may well represent contributions from both modern and former floras.

The occurrence of dumbbells and diatoms, diagnostic for the LLP community, generally corresponds with soils of present LLP islands, regardless of total opal contents (text table, p. 63; Table I-10). Areas of high total opal outside island boundaries have low contents of these






71


diagnostic forms. Taken alone, this result might suggest that the patterns of opal mass are relict from some former plant community different from those now occurring. To account for the concentric zonation, however, this community would need to have 1) occurred on approximately the same areas now occupied by LLP islands; 2) had a high rate of opal accumulation relative to surrounding communities; 3) had a fluctuating boundary. Evidence for such a community is lacking.

The obvious alternative to such an unknown predecessor community is the long-sustained occurrence of the LLPwiregrass community at or near present island locations, but with irregular and often large oscillations of boundaries over the past 5000 years. Opal mass would then reflect the duration of occupancy by island vegetation, with high opal zones representing stable cores around which community boundaries expanded and contracted. In contrast, the abundance of dumbbells and diatoms would reflect merely the recency of occupation by the LLP type. Weathering would have rendered these forms unrecognizable on areas long unoccupied.

In this view, the concentric zonation observed today (Fig. 1-14) is a palimpsest, with the opal patterns of recent communities superimposed on the now weathered patterns of the past. Interpretation of vegetative history based on such data must be tentative. Nevertheless, the







72

foregoing hypothesis appears to be the only explanation that accords with the totality of available evidence. The presence of early man and the probable role of fire associated with him are treated in the following sections. Stability of Present Boundaries

Present island boundaries, or recognizable evidence

of them, coincide with boundaries between "longleaf yellow pine" and "scrub and busshy pine" mapped during the General Land Office Surveys of 1820 to 1860 (on file, Marion County Courthouse, Ocala, Fla.). In the intervening years, however, the contact along most boundaries has been greatly disturbed. Although the National Forest was created in 1908, many private holdings on islands were not acquired until the 1930's. Large portions of Salt Springs, Syracuse, and Norwalk Islands still remain in private ownership with consequent pressure on surrounding forest lands. Longleaf stands were turpentined prior to 1900, but especially between 1910 and 1930. Mature pines were logged during and after the First World War, and the last old-growth stands were removed during the Second World War (U.S. Forest Service Historical File, Lake George Ranger District, Ocala N.F.). In addition, cultivation of field crops and citrus was attempted on at least Riverside, Norwalk, and Kerr Islands from about 1840 until the severe frosts in 1895-96 virtually ended large-scale settlement. These activities, together with grazing and temporary cultivation, especially







73

on Hughes and Pats Islands, inevitably destroyed the wiregrass cover and disturbed the surface soil.

Sand pine has invaded across its former border along

all islands (see two LLP-TO plots with sand pine, Table I-2). Stands of this species, often with turkey oak and scattered longleaf pine, also occupy large areas in the interiors of islands, as in the southern quarter of Riverside Island. Longleaf stumps, lighterwood, dark surface soils, and the common occurrence of dumbbell-shaped opal on such sites are unequivocal evidence of recent invasion of LLP parklands by sand pine and oaks. The youthful age and uncharacteristic groundcover of these stands are further evidence that once stable boundaries have been overrun. This situation is clearly a consequence of past policies that suppressed the normal fire regime of the islands: frequent ground fires that killed invading sand pine and reduced the number and size of oak sprouts. Once the continuous cover of wiregrass was eliminated by invading trees and shrubs, light ground fires were ineffective at reversing the invasion.

Similar invasion of the LLP community by sand pine has been reported on the Welaka Reserve, north of Lake George (Veno, 1976), and on Eglin Air Force Base in western Florida (Britt, 1973). On the latter area, the Choctawhatchee race of sand pine now dominates on some 40,000 ha formerly occupied by the LLP type.

Thus there is abundant evidence that sand pine readily invades the LLP community, and that the only obstacle to







74

its wider dominance is frequent fire. The contrary process, movement of longleaf pine into scrub, also seems to have occurred in the past. Table I-11 summarizes radial growth records for large residual longleaf pines occurring at four locations in typical scrubs near islands. Except for the solitary tree at Site 2, these occur as small scattered colonies of a dozen or so trees, rather than as single outliers. Low contents of opal in the soils and the absence of dark A-horizons indicate that these locations were not extensions of the nearby islands. Rather, their origin in 1830-1870 (Table I-11) coincides with the major influx of settlers to the area. It is probable that frequent wildfires during this period allowed colonization of previous scrub areas. Ring width patterns show an initial 30-60 year period of rapid growth followed by a sharp decline, mostly beginning between 1885 and 1901 (Table I-11). This decline likely marks regrowth of scrub and perhaps establishment of sand pine forests following the abandonment of agriculture. This interpretation is supported by contemporary descriptions (General Land Office Surveys, 1820-1860; Nash, 1895; Whitney, 1898) of sand pine as a scrubby or dwarfed tree with branches to the ground. Such description is greatly at variance with the present appearance of sand pine forests, but would have been appropriate to frequently burned stands.







75








Table I-11. Growth characteristics of old longleaf pines
growing outside island boundaries.



Growth Rate during
Specified Time Period
Tree Aget Diametert Height Early Later
(yrs.) (cm) (m) (rings/cm)

Site 1, 400 m S. of S. Boundary of Riverside Island

1 130 42.1 18.2 3 (1850-1895) 24 (1895-1980) 2 110 32.0 18.2 5 (1870-1930) 12 (1930-1980)

Site 2, 400 m W. of W. Boundary of Riverside Island

1 110 32.5 20.4 4 (1870-1900) 11 (1900-1980)

Site 3, 700 m W. of W. Boundary of Riverside Island; 1600 m N. of Site 2

1 119 48.8 18.8 3 (1861-1904) 11 (1904-1980) 2 133 40.2 17.8 3 (1847-1887) 11 (1887-1980) 3 150 54.2 20.2 4 (1830-1885) 11 (1885-1980)

Site 4, 30 m N. of N. Boundary of Hughes Island; on Paola Soil

1 151 47.4 -- 5 (1830-1888) 19 (1888-1981)



tMeasured at breast height.







76

These examples suggest that, dependent on the frequency of burning, both sand pine and longleaf pine can expand into areas previously occupied by the other. The general similarity of soil properties across present boundaries demonstrates that there have been no edaphic barriers to such oscillations in the past. Geographical and Archeological Evidence

Examination of the LLP islands reveals that they invariably include, or abut on, permanent sources of water. In addition, most contain some areas of recognizably more fertile soils, such as the Eustis series and the banded substratum phase of the Astatula series (Aydelott et al., 1975), or the "Eustis-like" soils previously mentioned (Table 1-7). These water sources, and perhaps the favorable soils, would have attracted early man.

Table 1-12 summarizes the geographical and archeological settings for nine islands. Portions of Riverside, Norwalk, Kerr, and Salt Springs Islands border on two large lakes, Delancey and Kerr (Fig. I-1). Additionally, a major spring occurs on the eastern edge of Salt Springs Island. Perennial springs occur in the center of Pats, and near the center and northern edge of Hughes Island. Syracuse Island borders the St. Johns River lowlands. Two smaller, unnamed islands are located on bluffs above the Oklawaha River. The location of the smaller of the two (#2, Table 1-12) is outlined on Fig. 1-14.







77




Table 1-12. Geographical and archeological settings of nine
longleaf pine islands.



Size Location and Descriptiov
Island (ha) Featuret of Archeological Sites

Riverside 3710 L, S Lake; PS Salt Springs 1780 L, Sp, S Lake, spring; 6 sites; M, m Norwalk 1190 L

Syracuse 500 R River; 2 sites (1200 m); M,m

Kerr 360 L

Pats 360 Sp, S Spring; PS Hughes 350 Sp, S Spring; M, PS #it 210 R, S River; 5 sites (200-100 m);m #2 60 R River; 3 sites (300-900 m); M, m, V



#1 centered at Sec. 21, T. 12 S., R. 24 E.; #2 at Sec. 31, T. 11 S., R. 24 E.

TFeatures occurring on or adjacent to islands. L = lake; Sp = spring; R = river; S = productive soils (see text). #Number of sites are those recorded by Florida Division of Archives, History, and Records Management; others are from the unpublished records of A. Dorian, U.S. Forest Service Archeologist, Ocala N.F. Distances in parentheses are maximums and minimums from the three islands located near rivers to riverine archeological sites. The next nearest archeological sites to these three islands were 4-5 km, air distance, along the rivers. M = middens; m = mound; V = village; PS = concentration of potshards.







78

Archeological records for the forest are meagre, and detailed work has been confined to riverine sites along the Oklawaha and St. Johns Rivers. Surface archeological surveys in the interior have been carried out only recently on Hughes, Pats, and portions of Riverside Islands (unpublished survey, A. Dorian, U.S. Forest Service Archeologist, Ocala N.F.). Both sources demonstrate a close association between LLP islands and significant prehistoric remains such as mounds, middens, concentrations of potshards, and village sites (Table 1-12). In all instances, these finds were adjacent to rivers, lakes, or springs.

Riverine sites were at the base of the bluffs, immediately below the two small islands along the Oklawaha River, but were separated from Syracuse Island by a 1000 mwide strip of forest. A village site was located on the well-drained slope between island #2 and the river. Sites have been located at Lake Delancey on Riverside Island (A. Dorian, personal communication, 1982), and at Lake Kerr and Salt Springs on Salt Springs Island. On Pats Island, artefacts were concentrated at the spring; on Hughes, they were near the two springs and throughout the central hardwood hammock (A. Dorian, personal communication, 1982). Surface surveys over extensive areas of SP-scrub have not yielded any such significant finds (A. Dorian, personal communication, 1982).







79

Essentially all recorded artefacts belong to the

St. Johns I and II Cultures. These people occupied the region from 500 B.C. to 1565 A.D., when they were displaced by immigrants from the north. The Ocala area was inhabited since about 4000 B.C., and the basic way of life followed by the St. Johns people had become established by 2000 B.C. (Milanich and Fairbanks, 1980). Known occupation sites are concentrated along major rivers, and therefore little is known about upland subsistence patterns. Maize arrived in the area between 1200 and 500 B.C., however, and evidence that St. Johns II people cultivated this grain, along with squash and gourds, has been found at one inland site (Milanich and Fairbanks, 1980).

General Discussion

{fires are set} almost every day
throughout the year in some part or other, by
the Indians, for the purpose of raising the
game, as also by the lightning. . .
(Bartram, 1791, along the St. Johns River,
Florida, p. 139.)

Evidence concerning the longleaf and sand pine communities on the study area can be summarized as follows:

1. The pollen record indicates that pine has predominated over the last 5000 years after succeeding oak and grass (Watts, 1969). The species of pine(s) is not known.







80

2. The present longleaf and sand pine communities differ in species composition, physiognomy, and relationship to fire. The longleaf community is similar to those occurring elsewhere on sandy uplands; the sand pine-scrub appears unique to central Florida and some coastal areas.

3. These two communities coexist, separated by boundaries that are (or were) remarkably well-defined and abrupt. These boundaries have been stable for at least the last 150 years (General Land Office Surveys, 1820-1860), and even when overrun by sand pine and oak their former positions are still evident.

4. Except where surface horizons have been darkened

under longleaf pine, boundaries between the two communities do not coincide with any differences in soil physical or chemical properties within the upper 5 m depth (Tables 1-3, 1-4, 1-5, I-6; Figs. 1-5, 1-8, I-10). Rather, boundaries transect a variety of profile types and substrates.

5. The two communities appear to differ in annual accumulation rates of biogenic opal in soils. Soil (0-60 cm) opal contents are markedly higher under longleaf pine locations remote from present boundaries. In contrast, soils from paired longleaf and sand pine plots only 200 m apart do not always differ appreciably in total opal contents (Table I-10; Fig. I-11). They do differ, however, in abundance of dumbbell-shaped phytoliths and diatom







81

frustules (Table I-10), two opaline forms diagnostic of occupancy by the longleaf pine community.

6. Schematic isolines of total opal contents of

soils (0-60 cm) are grossly concentric about core areas of islands, but do not necessarily conform to present island boundaries (Fig. 1-14). This concentricity suggests that island boundaries have expanded and contracted irregularly in the past. The most recent prehistoric changes were sufficiently long ago that diagnostic opal forms are no longer identifiable on some areas that may have been occupied by the longleaf pine community.

7. The extensive sand pine forest of the Ocala

National Forest probably owes its existence to a nearly continuous firebreak of rivers, lakes, and wetlands (Fig. I-1) that has excluded all but the greatest conflagrations originating outside the area. The longleaf pine islands, like longleaf communities elsewhere, could only have been maintained by fires at intervals of 1-5 years (Harper, 1914b;Christensen, 1981). Annual ignition by lightning strikes during the 1970 to 1981 period averaged only 1.7 per 10,000 ha on the forest (S. Holscher, Fire Control Officer, Ocala N.F., personal communication, 1982). This is far too infrequent to provide the necessary regularity of burning on isolated islands as small as 60 to 500 ha.







82

8. Repeated burning was a general practice among Indians of the historic period (Bartram, 1791; Heizer, 1956), and apparently had been for long periods in the past. Archeological history demonstrates the presence of man in the Ocala area for at least as long as pine forests have predominated (Milanich and Fairbanks, 1980), and specific evidence shows his presence on or immediately adjacent to longleaf pine islands (Table 1-12).

The totality of this evidence leads to the hypothesis that the longleaf pine islands were maintained through annual or frequent burning by early man: longleaf pine islands are therefore human artefacts.

This hypothesis requires that fires be restricted to the longleaf pine community rather than burning the surrounding scrub or sand pine with equal frequency. Such restriction is provided by the contrasting fuels of the two communities. Wiregrass and pine litter burn readily when dry, whereas the evergreen sand pine-scrub has been called a "fire-fighting machine" (Webber, 1935) because of its non-flammability under normal weather conditions. Once established, boundaries between the two could remain stable under a regime of frequent ground fires on the islands.

Despite this difference in fuels, events of the past century leave no doubt about fire occurrence in sand pinescrub, or scrub alone, and the high intensity of such fires.







83

Variations in climate and human use over the past millenia almost certainly determined fire frequency in longleaf and sand pine. Such differential burning seems the most likely agent causing expansion or contraction of island boundaries.

Maintenance of boundaries by Indian fires nevertheless leaves the question of origin unanswered. It is likely to remain a wholly speculative matter unless future distinction between longleaf and sand pine pollen in the fossil record may indicate which, if either, predominated 5000 years ago when pine replaced oak and grass in the region.

In any case, the relationship of longleaf pine islands to fire and man is similar to that of numerous other communities, including oak woodlands in the Northeast (Day, 1953); montane pine forests in the Philippines (Kowal, 1966); and perhaps prairies worldwide (Sauer, 1950; Stewart, 1953), and "caatinga" scrub in Amazonia (Anderson, 1981). In all such cases, the juxtaposition of contrasting plant communities is explainable only in light of the central role of fire, and man as the agent of ignition.













CHAPTER II
SOIL MIXING BY ANIMALS IN THE LONGLEAF PINE
AND SAND PINE COMMUNITIES

A diversity of animals inhabit the soil and affect its properties in various ways (Hole, 1981). In temperate regions, the emphasis has been on animal mixing within the upper 60 to 100 cm layer of soil, as by ants (Baxter and Hole, 1967; Lyford, 1963), earthworms (Buntley and Papendick, 1960), and small mammals (Abaturov, 1972). Deeper soil mixing has been reported for crayfish in Louisiana (to 4.5 m; Thorp, 1949), harvester ants in South Carolina (to 2.2 m; Gentry and Stiritz, 1972), and gopher tortoises in Florida (to 2.8 m; Hansen, 1963). Burrowing by such animals destroys stratification and homogenizes the soil to some depth.

This paper reports especially on deep tunnelling and soil mixing by a scarab beetle of east-central Florida, Peltotrupes youngi Howden,and on the relationship of beetle activity to vegetation type and abundance. Collateral information is also presented on the extent of soil mixing by pocket gophers (Geomys pinetus) which often occurred in the same study areas.

The Beetle

The genus Peltotrupes is included in the tribe Geotrupini (Coleoptera: Scarabaeidae) along with two




84







85

other soil-inhabiting genera. Geotrupes occurs in mesic, temperate regions throughout the world, and constructs tunnels less than 1 m deep. The flightless genus Mycotrupes is confined to the coastal plain of the southeastern U.S., and tunnels to depths of 2 m (Woodruff, 1973).

Species of Peltotrupes are metallic, robust scarab beetles, about 20 mm long and 16 mm wide, that occur as disjunct populations in Florida. The population occurring in the Ocala National Forest in Marion and Putnam counties is recognized as the species P. youngi (Woodruff, 1973). Suitable habitats are well-drained sandy soils vegetated with either sand pine (Pinus clausa)-scrub, or longleaf pine-turkey oak (P. palustris-Quercus laevis).

Adult beetles emerge from November onward and are

active until April. Burrows are constructed through the joint effort of a male and female (Fig. II-1). The burrow enters the soil at a slight angle, then continues vertically downward to an enlarged larval chamber (Young, 1950; Howden, 1952). The excavated soil is pushed up to form a surface mound, and some unknown quantity of surface litter is transported down to the chamber where the female deposits her eggs. Larvae feed either on the litter or on fungi that grow on the litter, and presumably complete development in one year (R. E. Woodruff, personal communication, 1981).

Materials and Methods

This study was conducted on the Lake George Ranger

District of the Ocala National Forest in east-central Florida.

































Figure II-1. Burrow of Peltotrupes youngi. (Based
partially on data in Young, 1950, and
Howden, 1952.)







87









- ~Surface Mound
600 g






Burrow of Peltotrupes youngi



Tunnel
2 cm. x 120 to 360 cm.












? Larval
S- Chamber
S 5 x 15 cm.







88

The soils are classified as the hyperthermic, uncoated families of Spodic and Typic Quartzipsamments. These are well-to excessively-drained sands with less than 5% silt plus clay in the upper 2 m layer. Below 2 m, however, texture and stratification are variable.

The two plant communities of interest are sand pinescrub and longleaf pine-turkey oak. These communities differ markedly in physiognomy and species composition. Scrub is an unique understory of evergreen shrubs, dwarf palms, and small trees. The chief species are myrtle oak (Quercus myrtifolia), sand live oak (Q. geminata), Chapman's oak (Q. chapmanii), crookedwood (Lyonia ferruginea), scrub palm (Sabal etonia), and saw palmetto (Serenoa repens). Density and height of scrub vary greatly. In contrast, longleaf pine occurs as an open parkland with a groundcover of wiregrass (Aristida sp.) and a diverse herbaceous flora (Harlow and Bielling, 1961). On sites where longleaf pine has not regenerated, turkey oak now dominates, with a much less abundant grass and forb flora.

Beetle activity was monitored in the 1980-81 and

1981-82 seasons on permanent sample plots in four vegetation categories: sand pine with thick scrub, sand pine with thin scrub, longleaf pine with thick grass, and longleaf pine with thin grass (Table II-1). Five study areas were selected in each category. Within each study area, a 5 m wide by 200 m long transect was installed along a randomly




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THE LONGLEAF PINE ISLANDS OF THE OCALA NATIONAL FOREST, FLORIDA: A SOIL STUDY BY PAUL JOHN KALIS Z A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 1982

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ACKNOWLEDGEMENTS I am grateful to E. L. Stone for the opportunity to study and work with hira over the past five years. Under his guidance, I have received an education in forest soils that is hard to equal. I also thank R. F. Fisher, H. L. Gholz, R. W. Johnson, and W. L. Pritchett for serving on my committee. Special thanks to Barbara Fischer for the typing of this dissertation, to Craig Reed and Karen Williams for help in the field, and to Mary McLeod for organizational and laboratory support.

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PREFACE This study is concerned with the soils of two contrasting forest communities that share a boundary. Chapter I characterizes and compares these soils and shows that soil properties do not account for the occurrence of the two types of vegetation. Chapter II deals with soil mixing by animals and the effects of mixing on soil properties. In particular, it is demonstrated that such mixing influences the appearance of surface soil horizons. The distinctness of these horizons has contributed to the belief that longleaf and sand pine soils are fundamentally different. The latter chapter therefore expands on the point originally made in Chapter I, that the sometimes striking differences in the appearance of surface soil layers under longleaf and sand pine are not indicative of distinct substrates; rather, they are superficial alterations caused by differences in plant communities and associated animal assemblages.

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TABLE OF CONTENTS Page ACKNOWLEDGEMENTS ii PREFACE iii LIST OF TABLES vi LIST OF FIGURES viii ABSTRACT X CHAPTER I ORIGIN AND STABILITY OF LONGLEAF PINE ISLANDS 1 Introduction 1 Study Area = 3 Location and Climate 3 Geology 3 Soils 7 Vegetation 7 Methods 12 Field Methods 12 Laboratory Analyses 13 Opal Extraction ..... 14 Nutrient Bioassay 14 Results and Discussion .......... 15 Surface Soil Profiles 15 Morphology ..... 15 Organic matter and charcoal 25 Fertility 32 Deep Soil Profiles 37 Morphology and texture 37 Chemical characteristics 40 Opal 49 Contents and morphology of opal in plants 50 Opal accumulations in longleaf and sand pine soil . = 52 Opal in soils of paired boundary plots 55 Opal patterning around longleaf pine islands 65 iv

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Page Stability of Present Boundaries 72 Geographical and Archeological Evidence 76 General Discussion ..... 79 II SOIL MIXING BY ANIMALS IN THE LONGLEAF PINE AND SAND PINE COMMUNITIES 84 Introduction 84 The Beetle 84 Materials and Methods 85 Results and Discussion 91 Soil Movement by Pelto trupes young i 91 Soil Movement by Other Animals '. T ... 95 Effects of Mixing on Soil Properties 9 8 APPENDICES I SCIENTIFIC NAMES OF SPECIES CITED 102 II LOCATION AND PARTIAL CHARACTERIZATION OF THE PAOLA SERIES PROFILES EXAMINED IN THIS STUDY 104 III DETERMINATION OF ORGANIC MATTER BY THREE STANDARD OXIDATION PROCEDURES .105 IV LOCATIONS OF 15 PAIRED PLOTS (SAMPLE POPULATION II) AND 60 ADDITIONAL SITES SAMPLED FOR BIOGENIC OPAL (SAMPLE POPULATION III) 10 8 V SUMMARY OF CHEMICAL AND PHYSICAL CHARACTERISTICS OF PAIRED LONGLEAF PINE AND SAND PINE BOUNDARY PLOTS 114 VI BIOGENIC OPAL CONTENTS OF 50 SOILS FROM SAMPLE POPULATION III 119 LITERATURE CITED 120 BIOGRAPHICAL SKETCH 127 V

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LIST OF TABLES Table Page I-l Woody plants on sand pine sites with thick and thin scrubs 9 1-2 Woody plants on longleaf pinewiregrass and longleaf pine-turkey oak sites 11 1-3 Summary of ANOVA of rye yields from 0-18 cm depths of paired longleaf and sand pine plots 33 1-4 Textural characteristics of the uppermost uniform soil layers of 5 m profiles from 15 pairs of longleaf and sand pine plots 41 1-5 Profile features or layers >^25 cm thick occurring between 200 and 500 cm in 15 pairs of longleaf and sand pine plots ... 42 1-6 Weighted average concentrations of extractable nutrients for two depths in paired longleaf and sand pine plots .... 43 1-7 Description of a soil profile with loamy lamellae, cemented-sand fragments, and finetextured subsoil under longleaf pine-wiregrass 48 1-8 Opal contents of mature foliage of common plants of the longleaf and sand pine communities 51 1-9 Two-year accumulations of grass and litter on five longleaf pine-wiregrass sites, with estimated annual opal input 54 I-IO Opal content, distribution, and abundance of diagnostic forms in soils on 10 paired longleaf and sand pine boundary plots 65 VI

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Table Page I-ll Growth characteristics of old longleaf pines growing outside island boundaries 75 1-12 Geographical and archeological settings of nine longleaf pine islands ... 11 II-l Selected characteristics of four vegetation categories: sand pine with thick and thin scrub; longleaf pine with thick and thin grass 89 II-2 Average number of mounds and total amount of soil deposited annually by Peltotrupes beetles and pocket gophers ... 96 II-3 Extractable element concentrations in Peltotrupes beetle mounds compared with adjacent 0-10 cm soil layers 99 vii

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LIST OF FIGURES Figure Page I-l Map of the Ocala National Forest, Florida. Study area is located north of State Highway 40 5 1-2 Soil catena diagram showing association among the Astatula and Paola series, and wet Spodosols and Inceptisols 18 1-3 Three general types of soil profiles with bleached surface (E) horizons under sand pine 20 1-4 Variation in thickness and color of the A-horizon of the Astatula series, dark surface phase, under longleaf pine 24 1-5 Mean organic matter contents of soil from paired longleaf and sand pine plots 27 1-6 Relationship between Munsell color value and organic matter contents of the 0-10, 10-20, and 20-30 cm depths of soil from paired longleaf and sand pine plots .... 29 1-7 Effect of finely-ground (<0.05 mm) charcoal on soil color 31 1-8 Relationship between rye yield and extractable native P on paired longleaf and sand pine 0-18 cm soil layers. All soils received the equivalent of 20 kg/ha N 35 1-9 Profile diagrams illustrating the variability in continuity, depth, and thickness of deep soil horizons along a longleaf -sand pine boundary 39 I-lO Weighted average concentrations of extractable Ca + Mg and P for the 5 m depth of 70 longleaf and sand pine sites both near to and remote from boundaries (Sample Population I) 47 viii

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Figure Vage I-ll Total opal contents of the 0 to 60 cm soil depth of paired longleaf and sand pine boundary plots (see also Table I-IO) 57 1-12 Relationship between organic matter and opal concentrations in 10 cm increments of the 0-60 cm soil depths from 10 paired longleaf and sand pine plots ... 59 1-13 Comparative distributions of organic matter and opal with depth on paired boundary plots 62 1-14 Schematic patterns of biogenic opal accumulation (mt/ha/60 cm) in the vicinity of four longleaf pine islands 6 8 II-l Burrow of Peltotrupes youngi ........ 87 I I -2 Comparison of the number of beetle mounds counted on twenty -one 300 m^ plots in 1981 and 1982 94 ix

PAGE 10

Abstract of Dissertation Presented to the Graduate Council of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy THE LONGLEAF PINE ISLANDS OF THE OCALA NATIONAL FOREST, FLORIDA: A SOIL STUDY by Paul John Kalisz December 19 82 Chairman: Dr. Earl L. Stone Major Department: Soil Science Two unlike forest communities co-exist on deep sands of the Ocala National Forest, Florida. Longleaf pinewiregrass-turkey oak (Pinus palustris Aristida stricta Quercus laevis ) occurs as isolated "islands," 60 to 4000 ha in area, in a matrix of sand pine-scrub ( Pinus clausaQuercus spp.). Striking contrasts in physiognomy and species composition, and sharp, stable boundaries, led to a belief that soil differences determined vegetation boundaries. Examination of soils to a 5 m depth at 130 locations revealed no consistent differences in profile morphology, particle size distribution, or available nutrients by chemical analysis and bioassay. Thus, X

PAGE 11

the hypothesis of causal soil differences under the two communities was not sustained. Differences in surface horizon (A, E) color were ascribed to additions of fine charcoal and to soilmixing by animals. Mixing, notably by scarab beetles ( Peltotrupes youngi ) and pocket gophers ( Geomys pinetus ) was much greater under longleaf than under sand pine. Biogenic opal extracted from soils (0-60 cm) at 75 locations provided evidence of vegetative history. Isolines of total opal mass were concentrically patterned around longleaf islands. This could be attributed to fluctuations in the sizes of islands. Opal morphology, and known vegetation changes, suggested that such fluctuations had occurred episodically over the past 5000 years Three lines of evidence led to the hypothesis that longleaf islands owe their existence to burning by early man: 1) The longleaf pine community is maintained only by ground fires at 1-3 year intervals. The incidence of lightning fires on the small islands is too low to ensure this regularity of burning. 2) Present islands are located adjacent to permanent sources of water, and often include areas of productive soils. 3) Man has occupied the region at least since 4000 B.C. Significant archeological remains are associated with longleaf islands, but not with the surrounding sand pine-scrub. xi

PAGE 12

Thus it is proposed that early man was attracted to favorable features found near present islands, and, by frequently burning, created or maintained an environment favorable to the longleaf pine community.

PAGE 13

CHAPTER I ORIGIN AND STABILITY OF THE LONGLEAF PINE ISLANDS Introduction The extensive range of longleaf pine ( Pinus palustris ) overlaps the more restricted range of sand pine (Pinus clausa ) along the central ridge of peninsular Florida. Here, characteristic communities of the two species intermingle, separated by boundaries that are unrelated to topography. The earliest descriptions emphasized the contrasts in physiognomy and species composition, and the sharpness of the contact between these communities (Vignoles, 1823; Nash, 1895; Whitney, 1898) The rich herbaceous flora of the longleaf parklands ("high pine land") contrasted with the woody thicket ("scrub") under sand pine: It is an impressive sight to stand at the border line between the scrub and the high pine land and notice the difference in the character of the vegetation. The high pine land is open, the trees are large and vigorous and the ground is covered with a crop of grass which gives very good grazing for cattle. These conditions stop abruptly at the edge of the scrub. The boundary between the high pine land and the scrub can be located without trouble within a few feet. ... In the scrub there is a dense growth of scrub oaks and low bushes and plants .... No grass is found, and only the most hardy desert plants grow. When pines grow it is the dwarf spruce pine {sand pine} and not the long-leaf pine, while on the other 1

PAGE 14

2 hand the spruce pine is not found across the border in the high pine lands proper. (Whitney, 1898, p. 14-15.) These floras, and the abruptness and apparent stability of their boundaries, have since been described in detail (Harper, 1914a, 1915, 1921; Mulvania, 1931; VJebber, 1935; Kurz, 1942; Laessle, 1958, 1968; Mohlenbrock, 1976) From the beginning, attempts were made to account for the marked differences in native growth. The central role played by fire in the ecology of both longleaf and sand pine was recognized: frequent ground fires maintained the longleaf pine community, whereas more violent fires at longer intervals killed and rejuvenated sand pine stands (Nash, 1895; Harper, 1914b; Webber, 1935). Fire, however, was not explicitly considered as a factor in the origin and long-term stability of the two communities, and the possible role of prehistoric fire was unmentioned. Some writers concluded that climate, topography, and soil did not account for the observed vegetation patterns (VJhitney, 189 8; Sellards, 1912; Webber, 1935). Nevertheless, almost by default, the idea emerged that community boundaries were determined by soil factors such as water-holding capacity (Mulvania, 1931; Kurz, 1942), and contents of organic matter (Kurz, 1942) and nutrients (Laessle, 1958). In particular, the thesis that the sand pine community is characteristic of especially nutrient-poor soils (Laessle, 1958) has persisted until the present (Christensen, 1981)

PAGE 15

The present study was undertaken to examine the possible role of soil differences as factors accounting for the juxtaposition of the longleaf and sand pine communities on the Ocala National Forest in east-central Florida (Fig. I-l) Preliminary examination of substrates failed to reveal such differences. A systematic study was then designed to fully characterize these soils, including features that might indicate vegetative history. These findings were integrated with available ecological, archeological and geographical information for a better understanding of the origin and stability of these communities Study Area Location and Climate This study was conducted on the Lake George Ranger District located in the northern portion of the Ocala National Forest (Fig. I-l) The climate is warm and humid. Annual precipitation is highly variable but averages about 1300 mm, with over 50% of the total between June and September (Aydelott, 19 66) Average daily maximum and minimum temperatures are 3 2C and 20 C for the April to October period, and 23C and 11C for November to March (Aydelott, 1966) Geology Brooks (1972) has given a generalized account of the geology of the forest, but the area is geologically complex and many details are not known.

PAGE 16

Figure I-l. Map of the Ocala National Forest, Florida. Study area is located north of State Highway 4 0

PAGE 17

5

PAGE 18

6 Surficial deposits are generally sands. In the western part of the study area, surface sands of varying thickness overlie the stratified sand, gravel, and kaolinitic clays of the "Citronelle Formation." This formation is continuous throughout the central ridge of Florida over a distance of about 240 km (Pirkle et al 1963). To the east, sands are locally underlain by discontinuous or irregular clay layers, sometimes associated with stratified sand and gravelly sand. The entire region is underlain by Ocala Limestone, but at such a depth that none of the soil profiles examined were calcareous. Elevations range from 49 m MSL in the northern part of the forest, to about 2 m along the St. Johns River. Surface drainage networks are absent, and the landscape is dominated by closed depressions. Topography is rolling, with varied landforms that include dune-like undulations and steep-sided sink holes. Land surfaces above 30 m MSL have been above sea level during the entire Pleistocene (Alt and Brooks, 1965); hence, landforms and sediments consist of an as yet undeciphered mixture of old and young elements. These landforms have been shaped by marine, karst, and aeolian processes that operated episodically in the past in conjunction with shifts in the regional climate, and with fluctuations in sea and ground water levels.

PAGE 19

Soils The most common soils on the study area are wellto excessively-drained Entisols. These have less than 5% silt plus clay in the upper profile, and are classified in the hyperthermic, uncoated families of Spodic (Paola series) and Typic (Astatula series) Quartzipsamments (Aydelott et al 1975). Well-drained Ultisols also occur as small inclusions where fine-textured layers are within 2 m of the surface. These soils are taxadjuncts to the sandy, siliceous, thermic family of Psammentic Paleudults (Eustis series) (Aydelott et al 1975). All soils are developed in parent materials devoid of primary minerals and consisting of quartz sand with small contents of iron and titanium heavy minerals. Clay-sized particles are primarily quartz, kaolinite, inter layered minerals, and lesser amounts of gibbsite (Carlisle et al 1978). Vegetation Sand and longleaf pines occupy approximately 100,000 and 30,000 ha, respectively, of well-drained soils on the forest (Aydelott et al 1975). Longleaf pine occurs around the periphery of the southern part of the forest in the lake region, and as isolated stands in the northern part (Fig. I-l) Traditionally, these isolated stands have been called "islands" in reference to their contrast

PAGE 20

8 to the surrounding sea of sand pine-scrub, or, in previous times, of scrub alone. There are at least nine islands which range in size from 60 to 4000 ha. All lie within the area that is north of the southern edge of Lake George and bounded on the west, north, and east by the Oklawaha and St. Johns Rivers (Fig. I-l) These islands and their surroundings are the subjects of this study. Sand pine-scrub occupies the center of the forest as a SSE-trending strip about 60 km long and 10 to 20 km wide. This is the largest block of sand pine known. The Oklawaha and St. Johns Rivers, and the extensive wetlands and lakes to the south (Fig. I-l) isolate this unique forest, and have served as firebreaks against all but the greatest conflagrations arising outside. "Scrub" refers to the thicket of evergreen shrubs, small trees, and dwarf palms that compose the understory of sand pine, and dominate in its absence. Height and density of scrub vary, depending on site conditions and age. The major species are myrtle oak ( Quercus myrtif olia Chapman's oak (Q. chapmanii ) sand live oak (Q. geminata ) and crookedwood ( Lyonia f erruginea ) (Table I-l) along with scrub palm (Sabal etonia ) and saw palmetto (Serenoa repens ) Grasses and forbs are virtually absent from scrub, except after disturbance. Under a regime of frequent fire, longleaf pine grows as an open parkland with a groundcover of wiregrass

PAGE 21

9 O • CD x; CN tn r-H 1 — I CN C •H • • • • • • +1 (0 ,c 00 o o o o O o E +" 4-' t-H V V V cn o (u (U ^ • CTi S-l (0 I-H iH A 1 < ^ \ cn 1 — 1 CN S (0 £ CN • QJ CO — cn 4-1 CO 42 C/3 O CN o n I-H a\ H +1 U 1— 1 1-H o o O o O £3 4-' 00 Cfl CJ • o C CD CN •H ^ U +J 0 ^ in 0 u cn CO 4-> 00 LD 00 u •H CN i:; in £1 CN •t-' II o I-H d) C to -p \ o ^ (U •H CO c -P dJ •H -P c cu I-H 5h d) 4-* in S-i 0 C CO cn to o Q) CO 4-) o o CO o "t? o o o +1 u P M 0 •H o i-H CN c •H (0 iH X! LD o CN CM m o CO o) cu 4-1 rH in >i V£> c d) fO (N •iH Cox; •H IT) c 0 <^ CO c 0 tJ -P o 0) 4-1 •H LD (N '3' CN n in o x; c 0 0 CO to o o C iH 4-1 CO 'S' d) a CO 5-1 4-1 C d) M 4-1 0 0 t3 S-i 3 0 >i ~ I-H 0 O CO Cji o • •H in in in CN r-H II -P ns O 0 x; c 14H C 1 C 4-1 0 (0 C 0 iH CD • 5h > T! Q d) CD (U Id • >i -P •iH e d) i-H 0 M 13 c 0 +1 c 0 (D 0 IS 3 U -H m (C3 CT> -H 4-1 -H c (d !h 0 CO CO M 5-1 •H fd d; 14H • >l C 4-> fd _B cy /Ti CO o CO 1 u H <+H e c -iH fd d) H d) o CO a. iH > a d) Ou (C (d e d) 0 fd 0) CO CO •r4 o x; d) fd (d 54 rH 3 C 54 o tji rH X 5h d; c 0 d) dj d) > Id •H >1 rH > < E-i o 6 a a M < +-

PAGE 22

10 (Aristida striata ) and a diverse herbaceous flora. The latter includes numerous members of the Fabaceae, Compositae, and Euphorbiaceae Woody plants other than pine are not prominent on frequently burned areas (LLP-WG type, Table 1-2) although gopher apple (Licania michauxii ) redroot ( Ceano thus microphyllus ) persimmon ( Diospyros virginiana ) pawpaw ( Asimina spp ) and oak (chiefly Q. laevis and Q. incana) are widely distributed. Sites from which longleaf pine has been removed without regeneration are often dominated by turkey oak (Q. laevis) (LLP-TO type, Table 1-2) The abundance and diversity of the herbaceous flora are much reduced. The longleaf and sand pine communities both depend on fire for their perpetuation, but the nature of the dependence differs markedly (Harper, 1914b; VJebber, 1935; Christensen, 1981) Sand pine, with its thin bark, and fine twigs and needles, is easily killed or damaged by fire. Fire, however, opens the closed cones characteristic of the Ocala sand pine, kills the scrub to ground level, and prepares a suitable seed bed. Thus, sand pine is generally believed to require fire at intervals of 20 to 70 years in order to successfully regenerate. Fires are not easily started in sand pine stands except under dry conditions, then, once ignited, they often burn cataclysmically (Webber, 1935; Cooper, 1973; Hough, 1973). Longleaf pine, on the other hand, is superbly adapted to fire (Chapman, 19 32; Wahlenberg, 1946) This tree

PAGE 23

11 01 O (U O -H I H +J o U) IS I 1-^ tn ^ cn -u O x: E-. cn I S i4 CO u 0) -p to S-i (0 IT) CO CO (C }-l cn •H I CO 'd c s •H I 10 0) iH cn c o CO -P c to 0 • Eh D 1 • CO +1 ^ to (0 0) o e a, — >i >i OJ (0 M x: o O 3 -P I M (1) -P c O O Xi Ti B O (N aI to 6 GJ -P CO o to u o 4-1 to E-i lO (U — S-i 10 < £ iHCNl (0 6 CO — to m ^to -p v •H to c c CO u o 3 o u u • o o c o Eh I Pu o •3" o o U3 o CNl 1X> o CN o in in CO •H CO S-t •H -p > CO CO CU to 0) to +J •rH rH to r-l to to u to CO c c: cu CO to H a to u E to to 0 c 0) CJ S-I -H cn c

PAGE 24

12 requires ground fires at intervals of one to three years in order to prevent encroachment of less fire-resistant competitors. Without fire to eliminate competition and prepare a seedbed, longleaf pine regenerates poorly (Chapman, 1932; Wahlenberg, 1946). Likewise, without fire, the characteristic herbs are buried by litter accumulation or suppressed by invading shrubs or trees. Methods Field Methods Three sample populations comprise the major basis of this investigation: I) Soil profiles were described and sampled to a depth of 5 m or more at 100 locations, both near to and remote from island boundaries. Some locations were selected after initial reconnaissance, others to replicate or expand on earlier observations. A 500 cm minimum depth was examined because sand pine roots extend to at least 400 cm, and longleaf pine roots to even greater depths. II) Fifteen pairs of plots, additional to the above, were established on either side of longleaf pine-sand pine boundaries along six islands. The pairs were located at randomly-selected points along segments of boundaries where both contact and stand conditions indicated minimal disturbance; individual plots were sited 100 m to each side of the boundary. Soils were examined and sampled to the 5 m depth.

PAGE 25

13 A bucket auger (7.5 cm diameter) was used to examine profiles and collect samples from the above two populations. Uniform profiles were sampled in 50 cm increments, while those with more complex horizon sequences were sampled in smaller increments. Hence, a minimum of 10 samples per profile were collected. At 10 of the 15 paired plots in Sample Population II, the upper 50 cm of soil was collected in 10 cm increments. Each increment consisted of a composite of 16 cores (2.5 cm diameter) collected in a 10 0 m^ area surrounding the bucket auger point. At these same 10 paired plots, samples of the 0-18 cm layer were collected for a bioassay study. Each sample was a composite of four 400 cm^ blocks. Ill) Composite samples from the 0-60 cm depth only were collected at 60 additional locations to provide information on the distribution of biogenic opal in soils. Each sample consisted of ten 2.5 cm diameter cores collected over a 100 m^ area. Laboratory Analyses Cations and phosphorus were extracted from soils with 0.05 N HCl plus 0.025 N H2SO4 (double-acid procedure; Mitchell and Rhue, 1979) For sands lacking easilyweatherable minerals, extractable cations are approximately equal to exchangeable cations, and extractable P is an empirical index of availability (J. A. G. Fiskell, personal communication, 19 82)

PAGE 26

14 Organic carbon in soils was determined by the WalkleyBlack procedure (Jackson, 19 58) and converted to organic matter using the conventional factor, 1.72. Silt plus clay (fraction <0.05 mm) was estimated gravimetrically after dispersion of the whole soil using Calgon, and separation by successive sedimentation and decantation. Sand was separated into standard USDA fractions using nested sieves. Opal Extraction Biogenic opal was extracted from whole soil samples by a standard sink-float technique (Rovner, 19 71) Organic matter was removed by dry-ashing at 450C overnight. Opal was then separated from the heavier fraction by five successive purification steps in an ethanol-bromof orm mixture of specific gravity 2.3. This was followed by further purification of the light isolate. Opal was extracted from washed tissue samples by ignition and removal of soluble ash with HCl. Isolated opal was examined for grain morphology and contamination with a 450x polarizing microscope. Nutrient Bioassay Rye was grown in a greenhouse on twenty 0-18 cm samples from Sample Population II The experiment was replicated with four fertilizer treatments: N2Q, N2oP]^o' ^20^10^20' ^40^10^20 (subscripts refer to the amounts added expressed as kg/ha) These small additions were

PAGE 27

15 aimed not at maximizing yields, but at revealing differences within the natural range of nutrient supply available to shallow-rooted plants. Seeds were planted in December in pots holding 4 kg of soil, and soil water contents were maintained at approximately 10% (w/w) The plants were harvested 51 days later, at flowering. Dry-weight yields of above ground parts were compared by ANOVA. Results and Discussion Surface Soil Profiles Morphology The most striking difference between the soils of the longleaf pine community (LLP) and sand pine community (SP) is in the horizonation of the upper profile. The soil survey of the Ocala National Forest (Aydelott et al 1975) shows the two primary soil series beneath SP to be Paola, with bleached (lOYR 6/1-8/1) surface, or "E," horizons, and As ta tula, with minimal surface horizon development. Soils on most LLP sites are also classified in the Astatula series, but are separated as a "dark surface phase" because of the presence of a dark (lOYR 3/1-4/2) surface, or "A," horizon. The Astatula, Paola, and dark surface Astatula series occupy approximately 75,000, 15,000, and 30,000 ha, respectively, on the forest (Aydelott et al 1975). Twelve of the 15 SP paired plots (Sample Population II) occurred on Astatula soils, and three on Paola. All LLP plots occurred on dark surface Astatula soils. Both the

PAGE 28

16 E-horizon of Paola soils and the A-horizon of LLP soils averaged about 20 cm thick on these plots, but varied from 5 to 50 cm over short distances. The E-horizons of the Paola series had abrupt, generally smooth boundaries marked by thin, discontinuous layers of organic-stained sand. In contrast, the boundaries of LLP A-horizons were diffuse and highly irregular, with tongues, krotovinas, and bits of charcoal and organic matter occurring well belov; the main body of the horizon. Throughout the forest, these three soils are interspersed in a complex pattern. Soils under SP can form a continuum between the Paola and Astatula series. A portion of such a continuum is illustrated in Fig. 1-2: the E-horizon of Profile 3 becomes progressively thinner and darker upslope. Over a distance of 50 m, with a rise of only 80 cm, the soil grades from a Paola with a thick E-horizon (Profile 3) to an Astatula with a thin A-horizon (Profile 1) Three general types of Paola profiles were observed during this study (Fig, 1-3; profile descriptions in Appendix II). The first type (Profile I, Fig. 1-3) occurs as an intermediate member in a drainage sequence from Astatula to wet Spodosols, as shown in Fig. 1-2. The E-horizon is underlain by a brightly-colored zone of welldrained, brownish yellow sand (Profile I, Fig. 1-3) that increases in thickness upslope. Below this layer, colors

PAGE 29

LO c Tj C T) C (U c 0 1 r~1 fO Q) (0 u lU (u X! II r* U r—\ L/l ^ II XI to r~i +-' 0) (0 t—\ rH rH O -H 0 -H C MH nj m M-i (0 0 -V (d •H 0 +J >H u M fo 03 CM m CU u tn •H rH > o d) C X! o ~ (U II C (1) Q) II H C P S > w -P •H SH -P rH CP C axj c (0 t) (0 0 0) . • 0 0 4-> Xi rH > (C EH cn 04 (0 C (0 0) !h 0} W -P (0 c >H tn to 0) O ,Q in -P (ji^ -H X3 II tji (1) a) -P n3 c 5 > to to Sh o •H ^ CP Q) S 73 0) rH 0) O W O C >-( -H rH rH XIlOtOUHWO^"^ W O O >H \ U to rH Em CM • rH t! to Q) 73 6 rH ^ ^1 -H C OJ II 2 tji M tO • in to • 100) QJfNC^J'J'tO •rHtn *C 3'0\,T3 T3 (N -H tn S H -H (0 ro ^ x; s o C rH £ to • to 2; rH Q) W V-l 6 -H Cn -p (N tn (0 0) o c to — (1) rH x: > • u rHto•Poo^p to -H O in O w r-\ ^ <-i X> '-^ (i) •H O O -P rH rH SH OlOVH-HiHtniHCUO tnCMCM^tO-HO>iCM (N I H
PAGE 30

18 <

PAGE 31

+J CO ^ QJ W O o Q) m O >-l -H iH M m 0) o 3 C Sh -H wo -P •H II ns ^ -H 0) fO O > ^ M (0 0) rO -i O rH X! -P O XI (0 CJi H • •P M H £ •H 0 to ^ rH II -H 0 CO U P 0 Q) rH rH iH rH rH •H rH • > 1 >i 0 CO n3 5-1 C ^H 5h Cr> 0 2 iH II ^ •H 0 0 • M rH m , 0 CUM U II m fd (0 (1) C 13 rH Cu fd rH >i to II 0) 4-1 u H 0) U C C 0) d C 0 C > IH 0) to 0 -P • u to (t) 0 XI -o Q) N II •H 0) -H II !h u u u O X 0 ^ -P H E-t Si X! to H 0) U •H

PAGE 32

20 5 o "55 CO 'c 5 o o O CD c o M *^ o sz c 5 o DD DO O 03 D a>

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21 are duller, and a distinct organic (Bh) horizon occurs near the water table. Such profiles commonly are found on lower slopes under SP, and along the margins of lakes and prairies under oaks, palms, and scrub. The second type of Paola profile is well drained and brightly colored throughout (Profile II, Fig. 1-3). This type lacks Bh-horizons, but is distinguished by the presence of sandy loam to sandy clay loam subsoil layers at depths ranging from 200 to 350 cm. In most cases, these finer-textured layers clearly belong to the underlying "Citronelle Formation." Paola soils of this type occur as small isolated patches throughout the central part of the study area. The vegetation is SP always with a thick scrub. The latter relationship suggests that the genesis of the E-horizon is in this case due to the greater biomass (Table I-l) and associated higher intensity of leaching under thick scrubs The third type of Paola profile lacks distinctive horizonation below the E-horizon (Profile III, Fig. 1-3). Diffuse organic stains and dull brown colors suggest, however, that Bh-horizons and water tables may have occurred in the past. This profile type has been examined in only a few locations in the eastern part of the study area. Its occurrence is not clearly related to present topography or elevation, but, since limestone occurs at relatively shallow depths in this part of the forest (Brooks, 1972),

PAGE 34

22 the landscape has undoubtably been altered by subsidence (Alt and Brooks, 1965) These profiles possibly developed in the past as intermediate catena members similar to Profile 2, Fig. 1-2, and Profile I, Fig. 1-3. These field observations suggest that soils now mapped as Paola (i.e., sandy soils with bleached surface layers) represent the convergence of developmental pathways Landscape position and stability, and vegetative history and productivity are factors controlling development of bleached surface layers. In all cases, the dominant process is podzolization In contrast, LLP sites appear as typical grasslands, with frequent fires, a rich herbaceous flora, and an active soil-mixing fauna (see Chap. II) On such sites, podzolization is inhibited (McKee, 1982) and the dominant soil-forming process is the incorporation of surface detritus and the homogenization of the upper soil. Dark A-horizons develop under these conditions. As illustrated in Fig. 1-4, both the color and thickness of these surface layers vary greatly. On some sites, dark surface Astatula soils can actually grade into either of the two SP soils. Differences in surface profile morphology on LLP and SP sites reflect the dominance of different soil-forming processes. Such superficial differences, although striking, do not account for the occurrence of the two communities, nor indicate fundamentally different substrates beneath them.

PAGE 35

4-' *• C -P (0 -H cn rH O 0) d •P 0 m O pL, +j in cn iH < C (0 0 c 0 ^ t3 -H -P (U +J tn nJ IM 0 03 (d C rH 0 • (0 N Q) O •H C O •H 0 CU ,c 1 m c < rH w tJiH C 0 0) rH T! 0 •H iH tn u d) U 0 OJ i-H C > 0 3 -H o PS C tn • fO n3 tn ^ rH tn &i tj tn > (U (U M C O (U ^ (0 4J U MH C •H (H -H C o •H Sh rH m C -73 -P O • •H ^ (tj P in ^ 73 nj (U Q) -H •H -H O Sh 5h Sh td o > tn tn Cm I H u

PAGE 36

o o o <\J ^ CD (^^) Hid3a

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25 Organic matter and charcoal Despite the dark surface beneath LLP, organic matter (ori) contents and distribution in the upper profiles did not differ across the LLP-SP boundary in the paired plot comparison (Fig. 1-5) Total OM in the upper 60 cm depth ranged from 27.4 to 138.5 mt/ha (mean, 56.7) in LLP, and from 27.2 to 77.0 mt/ha (mean, 43.1) in SP A power function approximately described distribution with depth in both soils (Fig. 1-5) Average concentrations decreased from 1.7% (range, 0.8 to 3.2%) in the 0-10 cm, to 0.2% (< 0.1 to 0.8%) in the 50-60 cm depth. As expected, soils with higher OM concentrations were generally darker on the Munsell color scale. Among soils with the same organic concentrations, however, LLP soils were consistently darker than SP soils (Fig. 1-6) This difference is due to the presence of finely-divided charcoal in LLP soils. Attempts to separate charcoal from organic-C by differential oxidation techniques yielded inconsistent results (procedures and results in Appendix III). This is due in part to the small quantities present, and to the influence of particle size, rather than total amount, on soil color. The effect of small amounts of fine charcoal on soil color is illustrated in Fig. 1-7. These results (Figs. 1-6, 1-7) agree with earlier speculation (Nash, 1895; Webber, 1935) that the dark surfaces of LLP soils result primarily from the charcoal added by frequent

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Figure 1-5. Mean organic matter contents of soil from paired longleaf (LLP) and sand pine (SP) plots (n=10; mean S.D.). The depth function of OM is Y = 163X-0.81 (r2 = 0.79) for LLP, and Y = 160X-0-80 (r2 = 0.53) for SP where: Y = percent of total (0-60 cm) OM in a 10 cm increment; X = increment midpoint (n=60)

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27 ORGANIC MATTER (mt/ha) 10 20 30 0-10 10-20 E o H CL LU Q 20-30 30-40 40-50 50-60 LLP SP I siiiiii '... .[ • • \

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0) 1 1 C (U 1 +J tjl c c 0 0 O H H Tj (U (1) 4-' -H r\ e O K •H 0 (d 4-1 >-) iH 0 -H 0 0 d) (0 -P > & (1) 0 >-H E 0 o o o I— t m rH 1 QJ O 0) • c tn s c 0 (0 i-H c (D V Q) O 0) C -P 1 •H 0) o ac H O (0 ^ rH m Ul 1 C o 'd 0 c •H (1) IT3 •p (0 4J m (0
PAGE 41

29 Q O < O _J • -4 Q •4 Q c\j LlI I5 o < o o •4 :• •4 •4 •4 •4 Q in ^ ro 3nnvA OJ

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O rH U -U 3 -P H-l +J (U (0 ^ C H — -H • 5-1 O M -( O o\o T3 iw rC nJ • O rH ^ tJi^: 0) Cn C -P 'd 0 -H 73 >irH 5 (0 C -H H m o o w o S-t iw (C a; n3 o c c ^ -p u +J H O oV M-i cn C (N H 0) u •H

PAGE 43

31

PAGE 44

32 fires. All surface soils examined contained charcoal fragments, but darkening seems due to a finely-divided component produced by ground fires on LLP sites. Fertility Historical references to differences in crop yields betv/een LLP and SP soils in the early settlement period (Whitney, 1898) prompted a bioassay of surface soils (0-18 cm) from paired plots (Sample Population II) The object was to determine if there were differences in nutrient availability important to the growth of shallowrooted plants, but undetected by standard chemical extraction procedures In this greenhouse study, yield of rye increased significantly (Table 1-3) with each added element and with the level of nitrogen: Yield (g/pot) ^^20 ^20^10 N20P10K20 ^40^10^20 LLP 1.5 2.1 2.7 3.9 SP 1.5 1.9 2.4 3.3 Yields from the pots receiving only N20 varied 12-fold, and were positively correlated with extractable native P (Fig. 1-8), but not with extractable Ca or Mg As Fig. 1-8 implies, the effect of location on yield was highly significant (p=0 0001) (Table 1-3). The mean difference between the two vegetation types, however, was significant only at the 5% level (Table 1-3) This difference was due almost entirely to inclusion of two Paola

PAGE 45

33 Table 1-3. Summary of ANOVA of rye yields from 0-18 cm depths of paired longleaf and sand pine plots (10 pairs x 4 fertilizer treatments) Significance Level (p) Comparisons All Paired Plots (n=10) Excluding Paola Soils (n=8) Among locations 0 .0001 0 .0001 Between vegetation types 0 .0258'^ 0 .6200 Among fertilizer treatments 0.0001^ 0 .0001+ Vegetation x fertilizer 0 .5089 0 8723 Longleaf pine > sand pine. ^40^10-^^20 > N20P10K20 > N20P10 > N20.

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Figure 1-8. Relationship between rye yield and extractable native P on paired longleaf and sand pine 0-18 cfm soil layers. All soils received the equivalent of 20 kg/ha N.

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35 EXTRACTABLE P(ppm)

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36 soils in the comparison. These samples consisted entirely of the leached E-horizon, and gave the lowest yields, less than 1.1 g/pot as compared with the mean of 2.4 g/pot for all SP soils. Exclusion of these two plots (and their LLP pairs) from analysis (Table 1-3) resulted in nearly identical mean yields for LLP and SP soils, 2.6 3 and 2.55 g/pot, respectively. Thus these results reveal no consequential differences in surface soil fertility associated with the boundaries between LLP and SP The exceptions are the Paola soils. Their low yields may account for some of the early reports (Whitney, 189 8) that garden crops could not be successfully grown on SP soils. The fertility status of LLP and SP surface soils can also be viewed through comparison with Florida agricultural soils using a rating scheme (IFAS, 19 81) of high (H) medium (M) and low (L) for OM and extractable nutrients. The percentage distribution of the 20 paired surface layers into these categories is compared below with Rhue and Sartain's (19 78) summary of cultivated soils: Distribution (%) OM P K Mg L M H L M H L M H L M H Agric soils 89 10 <1 30 15 55 69 17 14 15 20 65 LLP/SP soils 90 10 0 70 25 5 90 10 0 100 0 0 Organic matter, P, and K distributions of agricultural soils are for Entisols only, whereas that of Mg is for a

PAGE 49

37 variety of soils. Nitrogen contents are assumed to vary directly with OM. Results of the bioassay indicate that there is no consistent difference in the productivity of LLP and SP surface soils (Table 1-3) The comparison of these LLP-SP soils to agricultural soils (text table above) most of which have been fertilized, suggests that the former are not especially infertile relative to other unamended forest soils. Both results are contrary to the conventional generalization that the SP community is an indicator of particularly nutrient-poor sites (Laessle, 1958; Christensen, 1981) Further chemical characterization of these soils is given later under "Deep Soil Profiles." Deep Soil Profiles Morphology and texture Substrate characteristics varied throughout the study area. Geological strata and deep soil horizons were seldom parallel to the present surface, nor consistently related to elevation or landscape position. As a result, occurrence of particular layers changed unpredictably over distances of tens of meters, as did their depth, thickness, and continuity (Fig. 1-9) Characteristics such as texture, depth to a water table, and occurrence of strongly contrasting textural strata (Hillel and Talpaz, 1977) loamy lamellae or clay horizons (Oliver, 1978) within rooting depth obviously

PAGE 50

^ 1 (T3 tH 4J 0 •H a, iw D 3 (J OJ tn C iH QJ •H — H tH Sh JJ QJ QJ 0 c S-i cn t( 0 rd c o QJ x: rH -P c Cr> 0 C •H C X! 0 0 0 +J •H >lrH W +J JJ QJ tn (t3 •H (0 +J u iH (C Q) •H !T> O ^-l XI C -H QJ iH (0 0 TI H .H C o o C > cn Q) QJ C <-{ • 0) 0 (0 Q) w N O iH p •H CO CN tn 0 rH c X (d Q) •H u 4-) tH -H > -H -P 1 ^ 0 V4 C -P m QJ (0 tn > -H rH Q) rH rH Q) • tn 5-1 0 E-i W x: E 0 'O tn C LD 4-)
PAGE 51

39

PAGE 52

40 influence water availability and may affect the composition of natural vegetation. No consistent differences in such properties were found on the 15 paired plots straddling LLP-SP boundaries. These profiles were characterized by texturallyuniform surface layers of fine and medium sand containing 2 to 5% silt plus clay (chiefly clay) (Table 1-4) Thickness of this layer varied from less than 1 to 5 m, but means and ranges were similar beneath both vegetations. The same was true of the textural properties. Beneath the uniform surface layers, textural stratification was common, with layers ranging from very coarse sand and gravelly sand, to sandy clay loam. Neither the occurrence nor depth of specific characteristics was related to LLP vs. SP types (Table 1-5) Chemical characteristics Profiles were acid throughout, but pH values did not differ between vegetation types. Mean pH s were 4.7 and 5.0, respectively, in the 0-50 cm and 450-500 cm depths (n=30) The minimum pH was 4.5 in a surface horizon, and the maximum in a single subsoil was 5,1 The soil fertility status of the two communities was examined by using extractable base and P contents (Table 1-6) Potassium concentrations were uniformly below 0.01 me/100 g, and hence were not considered. The values given in Table 1-6 for the 0-200 and 200-500 cm depth are

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41 Table 1-4. Textural characteristics of the uppermost uniform soil layers of 5 m profiles from 15 pairs of longleaf and sand pine plots. (Small amounts of very coarse, coarse, and very fine sand also occurred in these layers.) Sand Pine Longleaf Pine Characteristic Mean Range Mean Range Thickness (cm) 275 70 -500 275 80 -500 Medium sand (0. 25-0.50 mm) (%) 54 43 -61 49 41 -64 Fine sand (0.10 -0.25 mm) (%) 37 26 -56 40 19 -64 Silt plus clay (<0 .05 mm) (%) 3 2 -4 3 2 -5

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42 Table 1-5. Profile features or layers >_25 cm thick occurring between 200 and 500 cm in 15 pairs of longleaf (LLP) and sand pine (SP) plots. Occurrence (no. of paired plots) Feature or Layer LLP Only SP Only Both Layer with >60% fine sand 2 2 4 Finely-stratified sand 3 0 1 Loamy lamellae 10 2 Layer with 5 to 10% clay 2 3 0 Layer with >10% clay 2 0 1 Layer with >2% gravel 2 0 2 Layer with >2% cemented-sand 2 0 0 fragments Organic layer (Bh horizon) Oil Water table Oil

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43 Table 1-6. Weighted average concentrations of extractable nutrients for two depths in paired longleaf (LLP) and sand pine (SP) plots. (* = difference between LLP and SP means significant at a=0.0 5.) Concentration 0-200 cm 200-500 cm Element LLP SP LLP SP All Sites (n=15) Ca + Mg (me/lOO g) 0.10 0.06 0.09 0-04 P (ppm) 7.8 3.8 9.1 9.9 Excluding LLP Sites with Layers Containing >10% Clay (n=13) Ca + Mg (me/100 g) 0.08 0.06 0.05 0.04 P (ppm) 3.3 2.7 9.1 9.8

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44 means weighted by horizon thickness and an average bulk density. Neither total bases nor P contents of the 200-500 cm layer differed significantly between the two vegetation types. Although extractable base concentrations appear slight, the totals for this layer alone equal or exceed the amounts likely to be contained in mature stands: 0.1 me/100 g in the 200-500 cm depth approximates 1000 kg/ha Ca or 600 kg/ha Mg Extractable P concentrations are surprisingly greater than might be expected, and represent substantial reservoirs of this element for deep-rooted plants Extractable bases in the surface 200 cm layer were significantly higher beneath LLP (Table 1-6) At two locations, however, a layer containing greater than 10% silt plus clay occurred below 300 cm under LLP but not SP (Table 1-5) The resulting large differences in Ca + Mg (me/100 g) are shown below; 0-200 cm 200-500 cm Location LLP SP LLP SP Pats Island 0 25 0.06 0 .31 0.04 Hughes Island 0 .19 0.08 0.33 0.06 Excluding these two pairs from analysis indicates no significant difference in base contents between the two types (Table 1-6)

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45 Data from extensive study plots (Sample Population I) have identified a zone of relatively high P concentration extending through Pats Island (Fig. I-l) and for unknown distances into SP along the north and south boundaries. Hence exclusion of the Pats Island site from the comparison also reduces the large mean difference in P concentrations in the 0-200 cm layers (Table 1-6) The preceding results from the paired plots (Sample Population II) (Table 1-6) were borne out by data from the more widely distributed samples (Sample Population I) Weighted average concentrations of P, and Ca + Mg for 70 such locations are shown in Fig. I-IO. Phosphorus values cluster between 1 and 30 ppm with no apparent relation to vegetation type. For the most part, base contents range between 0.0 2 and 0.1 me/100 g, again independent of vegetation. Seven profiles from LLP had average base contents of 0.2 to 0.6 me/100 g (Fig. I-IO) All seven were characterized by reddish loamy lamellae or subsoil horizons, somewhat finer sand textures, and sporadic occurrence of cemented-sand fragments. A representative profile of this type is described in Table 1-7. Such soils occurred as scattered inclusions on LLP sites, but were much less common under SP Some of these areas, with loamy lamellae within 200 cm of the surface, had been mapped as the Eustis and a banded substratum phase of the Astatula series (Aydellot et al 1975)

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Figure I-IO. Weighted average concentrations of extractable Ca + Mg and P for the 5 m depth of 70 longleaf and sand pine sites both near to and remote from boundaries (Sample Population I)

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47 0.6 0.5 o o SAND PINE LONGLEAF PINE E 0.3 A o 0.2 0, A •• • •}?• • A • • A ^ • •A • • ^ ^ A A A A >A A 0 10 20 30 40 P (ppm)

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48 Table 1-7. Description of a soil profile with loamy lamellae, cemented-sand fragments, and finetextured subsoil under longleaf pine-wiregrass SE 1/4 Sec. 17, T. 12 S., R. 25 E., Ocala National Forest, Florida. (This profile corresponds to 0.4 me/100 g Ca + Mg, and 2.2 ppm P on Fig. I-IO.) Depth (cm) Description 0-20 Dark grayish brown (lOYR 4/2) sand. 20-30 Brown (lOYR 5/3) sand. 30-60 Dark grayish brown (lOYR 4/2) sand. 50-130 Pale brown (lOYR 6/3) sand. 130-160 Very pale brown (lOYR 7/3) sand, with thin, indistinct lamellae. 160-200 Very pale brown (lOYR 7/3) sand, with distinct, strong brown (7.5YR 4/6) lamellae up to 5 cm thick and occupying 15% of the horizon. 200-300 Very pale brown (lOYR 8/3) sand, with thin, indistinct lamellae, and few coarse cementedsand fragments. 300-320 White (lOYR 8/2) sand. 320-370 Yellow (lOYR 7/8) loamy sand, with a faint network of very thin lamellae 370-400 Yellowish brown (lOYR 5/8) loamy sand to sandy loam, with few white (lOYR 8/1) mottles. 400-450 Yellowish red ( 5YR 5/8) sandy loam, with white (lOYR 8/1) and reddish brown (5YR 5/4) mottles. 4 50-500 As above, but sandy loam to sandy clay loam. 500-600 Equal parts white (lOYR 8/1) and reddish yellow (SYR 5/8) sandy clay loam.

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49 Profiles of this type seem to be the most productive soils for pine on the study area. The site index (at age 50, converted to meters from USDA, 19 29) of six dominant longleaf pines on two such soils averaged 24.8 0.9 m (mean S.D.) as compared with 19.7 2.4 m for 14 trees at five locations without fine-textured layers. Age at breast height was 57 to 82 years in the first instance, and 51 to 60 years in the second. Higher productivity of "Eustis-type" soils probably arises more from their greater water storage capacity than from higher exchange capacity and exchangeable base content. The close similarity in physical (Tables 1-4, 1-5) and chemical (Table 1-6; Fig. I-IO) characteristics indicates a generally uniform substrate across vegetation boundaries. Where differences occurred, they were not consistently related to vegetation type. Opal In other regions, phytoliths (plant opal bodies) extracted from the soil have served as evidence for the occurrence of prairie vegetation in what is now forest, and vice versa (Witty and Knox, 1964; Wilding and Drees, 1968a) This is possible because of the greater contents and characteristic polyhedral shapes of opal in grasses. One might expect similar differences to occur between the scruband grass-dominated understories of sand pine and longleaf pine forests. If boundaries between these two

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50 have indeed been stable over long periods, different quantities and morphological suites of opal should have accumulated in the two soils. This possibility was tested by examination of 1) opal mass, morphology, and distribution in the 0-60 cm soil depth of the 10 paired boundary plots previously studied (Sample Population II) (Figs. 1-5, 1-8); 2) opal mass and morphology in the 0-60 cm depth at 60 other locations (Sample Population III) These latter were selected to define patterns of opal acciimulation in the vicinity of LLP islands. Additionally, opal content and morphology of common plants of the two communities were examined. Content and morphology of opal in plants Of the five species with highest basal areas on SP sites (Table I-l) on Q. geminata had foliage opal contents greater than 0.5% (Table 1-8) Its phytoliths consisted primarily of curved needles as long as 80 pm, together with cup assemblages (sensu Wilding et al 1977), and smooth spheroids up to 20 pm in diameter. Opal contents of other oaks, sand pine, and Lyonia (Table 1-8) consisted mostly of unidentifiable fragments, with some rods (20-40 um long) cup assemblages, and spheroids (<_10 ym diameter) Foliage opal contents of Sabal etonia and Serenoa repens averaged over 3% (Table 1-8). Sabal opal occurred chiefly as unidentifiable fragments with some spheroids averaging 2.7 0.7 ym in diameter (details given on p. 63)

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51 Table 1-8. Opal contents of mature foliage of common plants of the longleaf and sandpine communities Species Opal (%) Sand Pine Community Pinus clausa (4) 0 .43 + 0 .08 Lyonia ferruginea (1) 0 29 Quercus myrtifolia (4) 0 .44 + 0 .10 Q. chapmanii (4) 0 .38 + 0 .10 Q. geminata (3) 1 .33 + 0 .48 Sabal etonia (3) 3 .14 + 0 84 Serenoa repens (3) 3 .67 + 1 .06 Longleaf Pine Community Pinus palustris (3) 1 .09 + 0 .26 Quercus laevis (1) 0 .39 Aristida stricta (3) 2 .48 + 0 .20 'Number in parenthesis represents collection sites. Composite samples of foliage from at leat 10 plants at each site were analysed in duplicate. a. +Mean S.D.

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Approximately 30% of Sabal spheroids were smooth, and the remainder were "pollen-like," with surfaces that were either roughened or studded with protuberances. Serenoa opal consisted of silicified guard cells and spheroids imbedded in fragile opaline sheets or ribbons. Spheroids averaged 5.4 2.0 ym in diameter; about 10% were smooth, the remainder pollen-like. The concentration of opal in wiregrass was 2.5% (Table 1-8), which is about average for grasses. These phytoliths were chiefly solid forms including rods, guard cells, and dumbbell shapes. The latter forms ranged from 10 to 30 xira long, and 5 to 12 ym wide. Surprisingly, opal concentration in longleaf pine needles was 1.1% (Table 1-8) This is over five times the amounts commonly reported for the genus (Miles and Singleton, 1975; Klein and Geis, 1978) Hence, unlike many species of forest trees, longleaf litter adds significant quantities of opal to the soil. Longleaf pine phytoliths were chiefly irregularly-rounded and, less commonly, elongate solids up to 20 ym in largest dimension. Rods, 20 to 40 pm long and 5 ym wide, were also common, with smaller numbers of cup assemblages and fragile encrustations. Opal accumulations in longleaf and sand pine soils Opal accumulation rates are the net result of biogenic input minus weathering losses from the soil. Accumulation rates beneath LLP and SP vegetations are not known. The

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53 estimated opal input on islands is in the vicinity of 30 to 40 kg/ha/yr, based on limited sampling (Table 1-9) Comparable estimates for the SP type are not available. Order of magnitude estimates can be derived from measures of total mass of foliage within 1.5 m of the ground (Harlow et al 1980) and the opal concentrations of scrub species (Table 1-8). Foliage mass within 1.5 m of the soil surface in SP stands from 1 to eO"*" years old ranged from 800 to 2300 kg/ha; the average for stands older than 25 years was about 1000 kg/ha. Foliage of sand pine and that of the upper crowns of Lyonia and taller oaks is not included. Tall shrubs are sparse, however, in the SP-thin scrub type (Table I-l) which predominates on the study area. Thus, although the relationship of total scrub foliage mass to annual litter fall is unknown, the latter can scarcely exceed the 2500 kg/ha/yr rate of LLP sites (Table 1-9) and probably is much less. Opal contents of sand pine and scrub species, apart from the two palms, are much lower than in longleaf pine and wiregrass (Tables 1-8, 1-9). Annual foliage productions, hence opal inputs, of the palms are unknown. Areas where palms are presently most abundant have low total biomass (thin scrubs. Table I-l) and low contents of opal in the soil. The ubiquity of palm-like spheroids in soils suggests that these species were more widely distributed and perhaps more abundant in the past. At present, however, their

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Table 1-9. Two-year accumulations of grass and litter on five longleaf pine-wiregrass sites, with estimated annual opal input. Grass includes all attached v/iregrass foliage; litter is chiefly longleaf needles with some grass. (n=5, except for grass opal %, where n=3) Mass (kg/ha) Opal (%) Annual Opal Input (kg/ha/yr) Grass Litter 1400 500 3600 1400 2.48 0.20 2.15 0.57 17 19 36 'Two-year accumulations.

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55 abundance is limited, and almost certainly total annual opal input in the SP community is much lower than in LLP. Weathering rates of opal in the humid, warirv excessivelydrained soils of the study area are open to conjecture. The increased solubility of amorphous silica with temperature (Wilding et al 1977) should lead to more rapid losses than occur in northern climates. Solid forms of low surface area are more stable (Bartoli and Wilding, 19 30) and hence accumulate. Such forms predominate in longleaf pine needles and wiregrass. In contrast, the distinctive thin needles of Q. geminata are seldom observed in soils. The thin opaline matrix of palm foliage is also short-lived, but spheroids persist, and palm-like spheroids are the most common forms in SP soils Thus, a greater accumulation of opal under the LLP community probably results both from a greater stability of opal forms, and from a larger annual input. Opal in soils of paired boundary plots (1) Mass. The total mass of biogenic opal ranged from less than 1 to more than 10 mt/ha in the 0-60 cm depth (Fig. I-ll) There was no correlation of the amounts found in the LLP and SP members of the same pair. Opal concentrations in the 0-10 cm layers were substantially higher under LLP (Fig. 1-12), and total amounts were greater under LLP at nine of the 10 locations. The differences between LLP and SP were not consistent, however, ranging

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(0 e o O H 04 o >l M O (0 -P C O ^3 O 0) XI -P ^ CI4 <4-l Cn o CO (U +J c (U o. -p o c o (d CO H O (CJ O EH-(U 3 •H Em

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(UJ009/DM/IUJ) ivdO

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Figure 1-12. Relationship between organic matter and opal concentrations in 10 cm increments of the 0-60 cm soil depths from 10 paired longleaf and sand pine plots. Open symbols designate the 0-10 cm increments.

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59 "I A Longleaf pine • Sand pine A • • 1 t... • I o o o o o 0.5 ,0 1.5 2.0 ORGANIC MATTER (%) 2.5 3.0

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60 from 200 to 9000 kg/ha/60 cm (Fig. I-ll) (2) Distribution with depth. Opal contents decreased with soil depth in both communities (Fig. 1-13) Under LLP, the distribution of opal was a power function of depth, and approximated that of OM. Opal was distributed more erratically in SP soils. As compared with either the distribution of organic matter, or with that of opal under LLP, a smaller percentage of the total opal in SP soil occurred above 20 cm (Fig. 1-13) The diffuse relationships between amounts of opal and OM in individual layers are revealed by a scatter diagram (Fig. 1-12). Opal increased as OM increased in LLP soils, whereas the relationship was poor under SP (3) Morphology. Two types of biogenic opal, dumbbellshaped phytoliths and diatom frustules, were used as indicators of the LLP community. Dumbbells are diagnostic for Panicoid grasses (Twiss et al 1969), including wiregrass. Soil-inhabiting diatoms characteristically inhabit open LLP stands, but not the shady scrub (Smith, 1944; Patrick, 19 77) although the latter may have been more open prior to effective fire control. Thus it is not surprising that both of these forms accumulate in soils on the LLP side of stable boundaries. Opal assemblages from the two communities at the 10 boundary locations differed in proportion of characteristic forms :

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Figure 1-13. Comparative distributions of organic matter and opal with depth on paired boundary plots. Depth functions for opal are Y = 10 8X-0-66 (r^ = 0.52) for longleaf pine soils (LLP), and Y = 39X-0-33 (r2 = 0.15) for sand pine soils (SP) Y = % of total (0-60 cm) opal in a 10 cm increment; X = increment midpoint; (n=60) (compare with Figure 1-5)

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62 DISTRIBUTION (%) 10 20 30 40 50 1 1 \ 1 1

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63 Mean Percent of >.5 \im Grains (n=20 ,000) LLP SP Dumbbells 1.3 0.2 Diatoms 0.5 0.2 Spheroids 10.9 20.7 (* = significant at a=0.05) Dumbbells were six times as common in LLP soils. Diatoms, and other solid forms identifiable as grass and longleaf needle phytoliths (see "Content and morphology of opal in plants") were common in LLP soils, but less frequent in SP soils Opal from SP soils consisted primarily of indistinct fragments and spheroidal shapes (see text table above) Some spheroids were identical in size and ornamentation to those from scrub palm and saw palmetto (See "Content and morphology of opal in plants") Others were substantially larger than spheroids in these palms: Diameter of Spheroid (urn) Mean S.D. Range Scrub Palm (n=100) 2.7 0.7 1-4 Saw Palmetto (n=100) 5.4 2.0 1-11 SP soil (n=150) 8.5 3.7 1-20 The origin of the larger spheroids is unknown. Such forms were either absent or present in low numbers in the plants listed in Tables I-l and 1-2 (see "Content and morphology

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64 of opal in plants") ; nor were they found in bracken ( Pteridium aquilinum ) beargrass ( Yucca f ilamentosa ) dogfennel ( Eupatorium sp ) cabbage palm ( Sabal palmetto ) or Andropo gon grasses, all of which occur in the area. Fragmented sponge spicules were widely but sparsely distributed in both LLP and SP soils. Their occurrence was not related to proximity to lakes or wet prairies. (4) Discussion. The bulk of the total biogenic opal in these soils occurs in the upper 60 cm depth. Concentrations were generally below 0.02% in the 50-60 cm increments. No opal was found in or above illuvial layers occurring between 200 and 600 cm, including Bh-horizons (n=5) loamy lamellae (n=2) and the upper parts of clay layers (n=3) This lack of evidence for downward migration agrees with observations in Illinois soils (Jones and Beavers, 1964) but not with the opal accumulations above some clay layers in Australia (Hallsworth and Waring, 1964) Total opal mass in soils from the boundary plots was not clearly related to present vegetation type (Fig. I11) Distribution with depth (Fig. 1-13) and morphology (see text table, p. 63) differed by type when averaged over all locations. When individual pairs of LLP and SP boundary plots are compared, however, such differences are not consistent (Table I-IO) At some locations (e.g.. Pair No. 6, Table I-IO) opal mass and occurrence of diagnostic forms are clearly different in the two soils, whereas at others, the values are similar.

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65 Ui B O -P OP -ftn H W iH 0) X! e Q M to a o e CO o o o V o U3 O V • c O (0 M M H •H (0 T} Pj C (0 3 in o o in CM o o o Ui in o o V o o in o o o ro o n rH 00 o o o o CM o ro o o V in ro o CO o in o rH 00 00 e CO 'a o cu 0 ro vA in rH CN rH 00 1^ in < rH (0 03 00 S CO ro ro ro ro 0 u o Pn <4-l in CN ro > rH iH > 0 ns •H H 03 0 •H CO K CO CO o rH CN ro in rH rH rH rH rH rH o o o rvj II c 01 C -H (0 Sh Cn e in A| UH o -p C (U o 0)

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66 These large inconsistencies would not be expected if the abrupt boundaries observed in the recent past (Nash, 189 5; Whitney, 189 8) had in fact been stable over long periods of time. Hence these data lead to questions about the stability of LLP-SP contacts. Opal patterning around longleaf pine islands (1) Mass, morphology, and patterning. Opal mass from the 60 additional sample sites in the vicinity of islands ranged from minima of less than 1 mt/ha/60 cm to maxima of 6.0 and 15.5 mt/ha/60 cm on SP and LLP sites, respectively (See Appendix VI) Morphological differences between the two opal assemblages were similar to those found on the boundary plots (see text table, p. 63 ) except that dumbbells and diatoms were virtually absent from SP sites that were distant from boundaries. Diombbells were about 30 times greater, and diatoms 6 times greater in the >_5 ym opal fraction from LLP than from SP locations. Dumbbells occurred in all LLP soils, including those now vegetated with turkey oak, and presently lacking grass. This demonstrates that the extensive areas of turkey oak (LLP-TO type. Table 1-2) on this forest formerly supported longleaf pine parklands with abundant grass (LLP-WG type. Table 1-2) Intensive sampling in portions of the study area revealed a distinct patterning of opal mass around LLP islands (Fig. 1-14). The zones of highest opal contents were always

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CO tJicH H -H nj -P C S u to d (1) 0) o o S-l -P ^ VD a (0 o \ -< iH nj CO 3 J -P CO g g C M O 3 -H OJ O • O -P o O CO Oj -P (C -a 0) \ (0 iH to a CO g • -P 0 -H CO C g u •P 0 u 3 i -p c 0 •H g c • (U ji: 0 dJ S-l CO OJ > 3 s < H I H u •H

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68

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69 located on islands, but the surrounding isolines did not conform to present island boundaries. The opal isolines of Fig. 1-14 are based on relatively few points, and are more diagrammatic than definitive. Zones of high opal may actually be larger in area or more numerous, and isoline patterns may differ in detail. Nevertheless, evidence from the four most intensively sampled islands (Fig. 1-14) and from other islands sampled in less detail, indicates that concentration of opal in the vicinity of islands is general throughout the study area. (2) Discussion. There are few plausible hypotheses to account for this concentric zonation of opal. Topographic relationships and particle size distributions alone rule out explanations based on differential erosion and deposition. Sponge spicules, which have been used as indicators of aeolian deposits on uplands (Wilding and Drees, 196 8b) were not concentrated in areas of high opal content. Moreover, the monotonic decrease of total opal with depth (Fig. 1-13) indicates accumulation in situ rather than a transported origin (Wilding et al 1977) Apparent differences in biomass productivity are evident throughout the area (Table 1-3; Fig. 1-8, I-IO) and must influence the annual input of opal within vegetation types. Such current differences in productivity cannot account for the concentric patterns shown in Fig. 1-14. Three of the four zones of highest opal correspond to areas of the

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70 relatively more productive "Eustis-like" soils (Table 1-7) The fourth, on Pats Island, is underlain by soils exceptionally high in P and bases. There is no evidence of productivity gradients outward from these centers, however, that might result in concentric opal patterning. Moreover, relatively high opal contents also occur in soils that are apparently less productive than the four noted above. The observed patterns of opal distribution (Fig. 1-14) are consistent with a hypothesis of shifting boundaries between communities with different rates of opal accumulation (Miles and Singleton, 1975) Biogenic opal is reported to persist in some Ohio soils for periods of up to 13,000 years (Wilding, 1967) The vegetation of the Ocala area has changed drastically in a much shorter time than this. A pollen profile from Mud Lake, on the western edge of the study area (Fig. I-l) indicates a shift from dominance by oaks, grass, and forbs between 8000 and 5000 B.P., to a preponderance of pine (species unknown) and disappearance of grass after 5000 B.P. (Watts, 1969) Hence, opal extracted from these soils may well represent contributions from both modern and former floras. The occurrence of dumbbells and diatoms, diagnostic for the LLP community, generally corresponds with soils of present LLP islands, regardless of total opal contents (text table, p. 63; Table I-lO) Areas of high total opal outside island boundaries have low contents of these

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71 diagnostic forms. Taken alone, this result might suggest that the patterns of opal mass are relict from some former plant community different from those now occurring. To account for the concentric zonation, however, this community would need to have 1) occurred on approximately the same areas now occupied by LLP islands; 2) had a high rate of opal accumulation relative to surrounding communities; 3) had a fluctuating boundary. Evidence for such a community is lacking. The obvious alternative to such an unknown predecessor community is the long-sustained occurrence of the LLPwiregrass community at or near present island locations, but with irregular and often large oscillations of boundaries over the past 5000 years. Opal mass would then reflect the duration of occupancy by island vegetation, with high opal zones representing stable cores around which community boundaries expanded and contracted. In contrast, the abundance of dumbbells and diatoms would reflect merely the recency of occupation by the LLP type. Weathering would have rendered these forms unrecognizable on areas long unoccupied. In this view, the concentric zonation observed today (Jig. 1-14) is a palimpsest, with the opal patterns of recent communities superimposed on the now weathered patterns of the past. Interpretation of vegetative history based on such data must be tentative. Nevertheless, the

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72 foregoing hypothesis appears to be the only explanation that accords with the totality of available evidence. The presence of early man and the probable role of fire associated with him are treated in the following sections. Stability of Present Boundaries Present island boundaries, or recognizable evidence of them, coincide with boundaries between "longleaf yellow pine" and "scrub and busshy pine" mapped during the General Land Office Surveys of 1820 to 1860 (on file, Marion County Courthouse, Ocala, Fla.). In the intervening years, however, the contact along most boundaries has been greatly disturbed. Although the National Forest was created in 1908, many private holdings on islands were not acquired until the 19 30 's. Large portions of Salt Springs, Syracuse, and Norwalk Islands still remain in private ownership with consequent pressure on surrounding forest lands. Longleaf stands were turpentined prior to 1900, but especially between 1910 and 1930. Mature pines were logged during and after the First World War, and the last old-growth stands were removed during the Second World War (U.S. Forest Service Historical File, Lake George Ranger District, Ocala N.F.). In addition, cultivation of field crops and citrus was attempted on at least Riverside, Norwalk, and Xerr Islands from about 1840 until the severe frosts in 1895-96 virtually ended large-scale settlement. These activities, together with grazing and temporary cultivation, especially

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73 on Hughes and Pats Islands, inevitably destroyed the wiregrass cover and disturbed the surface soil. Sand pine has invaded across its former border along all islands (see two LLP-TO plots with sand pine. Table 1-2) Stands of this species, often with turkey oak and scattered longleaf pine, also occupy large areas in the interiors of islands, as in the southern quarter of Riverside Island. Longleaf stumps, lighterwood, dark surface soils, and the common occurrence of dumbbell-shaped opal on such sites are unequivocal evidence of recent invasion of LLP parklands by sand pine and oaks. The youthful age and uncharacteristic groundcover of these stands are further evidence that once stable boundaries have been overrun. This situation is clearly a consequence of past policies that suppressed the normal fire regime of the islands: frequent ground fires that killed invading sand pine and reduced the number and size of oak sprouts. Once the continuous cover of wiregrass was eliminated by invading trees and shrubs, light ground fires were ineffective at reversing the invasion. Similar invasion of the LLP community by sand pine has been reported on the Welaka Reserve, north of Lake George (Veno, 1976) and on Eglin Air Force Base in western Florida (Britt, 19 73) On the latter area, the Choctawha tehee race of sand pine now dominates on some 40,000 ha formerly occupied by the LLP type. Thus there is abundant evidence that sand pine readily invades the LLP community, and that the only obstacle to

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74 its wider dominance is frequent fire. The contrary process, movement of longleaf pine into scrub, also seems to have occurred in the past. Table I-ll summarizes radial growth records for large residual longleaf pines occurring at four locations in typical scrubs near islands. Except for the solitary tree at Site 2, these occur as small scattered colonies of a dozen or so trees, rather than as single outliers. Low contents of opal in the soils and the absence of dark A-horizons indicate that these locations were not extensions of the nearby islands. Rather, their origin in 1830-1870 (Table I-ll) coincides with the major influx of settlers to the area. It is probable that frequent wildfires during this period allowed colonization of previous scrub areas. Ring width patterns show an initial 30-60 year period of rapid growth follov/ed by a sharp decline, mostly beginning between 1885 and 1901 (Table I-ll) This decline likely marks regrowth of scrub and perhaps establishment of sand pine forests following the abandonment of agriculture. This interpretation is supported by contemporary descriptions (General Land Office Surveys, 1820-1860; Nash, 189 5; Whitney, 189 8) of sand pine as a scrubby or dwarfed tree with branches to the ground. Such description is greatly at variance with the present appearance of sand pine forests, but would have been appropriate to frequently burned stands.

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75 Table I-ll. Growth characteristics of old longleaf pines growing outside island boundaries. Growth Rate during Specified Time Period Tree Age'' Diameter''' Height Early Later (yrs ) (cm) (m) (rings/cm) Site 1, 400 m S. of S. Boundary of Riverside Island 1 130 42.1 18.2 3 (1850-1895) 24 (1895-1980) 2 110 32.0 18.2 5 (1870-1930) 12 (1930-1980) Site 2, 400 m W. of W. Boundary of Riverside Island 1 110 32.5 20.4 4 (1870-1900) 11 (1900-1980) Site 3, 700 m W. of W. Boundary of Riverside Island ; 1600 m N. of Site 2 1 119 48.8 18.8 3 (1861-1904) 11 (1904-1980) 2 133 40.2 17.8 3 (1847-1887) 11 (1887-1980) 3 150 54.2 20.2 4 (1830-1885) 11 (1885-1980) Site 4, 30 m N. of N. Boundary of Hughes Island ; on Paola Soil 1 151 47.4 — 5 (1830-1888) 19 (1888-1981) Measured at breast height.

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76 These examples suggest that dependent on the frequency of burning, both sand pine and longleaf pine can expand into areas previously occupied by the other. The general similarity of soil properties across present boundaries demonstrates that there have been no edaphic barriers to such oscillations in the past. Geographical and Archeological Evidence Examination of the LLP islands reveals that they invariably include, or abut on, permanent sources of water. In addition, most contain some areas of recognizably more fertile soils, such as the Eustis series and the banded substratum phase of the Astatula series (Aydelott et_al. 1975) or the "Eustis-like" soils previously mentioned (Table 1-7). These water sources, and perhaps the favorable soils, would have attracted early man. Table 1-12 summarizes the geographical and archeological settings for nine islands. Portions of Riverside, Norwalk, Kerr, and Salt Springs Islands border on two large lakes, Delancey and Kerr (Fig, I-l) Additionally, a major spring occurs on the eastern edge of Salt Springs Island. Perennial springs occur in the center of Pats, and near the center and northern edge of Hughes Island. Syracuse Island borders the St. Johns River lowlands. Two smaller, unnamed islands are located on bluffs above the Oklawaha River. The location of the smaller of the two (#2, Table 1-12) is outlined on Fig. 1-14.

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77 Table 1-12. Geographical and archeological settings of nine longleaf pine islands. Island o 1 ze (ha) Feature^ jjOCauxon dnu. ue scr ip uxon of Archeological Sites* Riverside 3710 L, S Lake; PS Salt Springs 1780 L, Sp, S Lake, spring; 6 sites; M, m Norwalk 1190 L Syracuse 500 R River; 2 sites (1200 m) ; iyi,m Kerr 360 L Pats 360 Sp, S Spring; PS Hughes 350 Sp, S Spring; M, PS #1+ 210 R, S River; 5 sites (200-100 m) ; #2^ 60 R River; 3 sites (300-900 m) ; M, m, V #1 centered at Sec. 21, T. 12 S., R. 24 E.; #2 at Sec. 31, T. 11 S. R. 24 E. ^Features occurring on or adjacent to islands. L = lake; Sp = spring; R = river; S = productive soils (see text) #Number of sites are those recorded by Florida Division of Archives, History, and Records Management; others are from the unpublished records of A. Dorian, U.S. Forest Service Archeologis t, Ocala N.F. Distances in parentheses are maximums and minimums from the three islands located near rivers to riverine archeological sites. The next nearest archeological sites to these three islands were 4-5 km, air distance, along the rivers. M = middens; m = mound; V = village; PS = concentration of potshards.

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78 Archeological records for the forest are meagre, and detailed work has been confined to riverine sites along the Oklawaha and St. Johns Rivers. Surface archeological surveys in the interior have been carried out only recently on Hughes, Pats, and portions of Riverside Islands (unpublished survey, A. Dorian, U.S. Forest Service Archeologist, Ocala N.F.). Both sources demonstrate a close association between LLP islands and significant prehistoric remains such as mounds, middens, concentrations of potshards, and village sites (Table 1-12) In all instances, these finds were adjacent to rivers, lakes, or springs Riverine sites were at the base of the bluffs, immediately below the two small islands along the Oklawaha River, but were separated from Syracuse Island by a 1000 mwide strip of forest. A village site was located on the well-drained slope between island #2 and the river. Sites have been located at Lake Delancey on Riverside Island (A. Dorian, personal communication, 19 82) and at Lake Kerr and Salt Springs on Salt Springs Island. On Pats Island, artefacts were concentrated at the spring; on Hughes, they were near the two springs and throughout the central hardwood hammock (A. Dorian, personal communication, 19 82) Surface surveys over extensive areas of SP-scrub have not yielded any such significant finds (A. Dorian, personal communication, 19 82)

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79 Essentially all recorded artefacts belong to the St. Johns I and II Cultures. These people occupied the region from 500 B.C. to 1565 A.D., when they were displaced by immigrants from the north. The Ocala area was inhabited since about 4000 B.C., and the basic way of life followed by the St. Johns people had become established by 2000 B.C. (Milanich and Fairbanks, 19 80) Known occupation sites are concentrated along major rivers, and therefore little is known about upland subsistence patterns. Maize arrived in the area between 1200 and 500 B.C., however, and evidence that St. Johns II people cultivated this grain, along with squash and gourds, has been found at one inland site (Milanich and Fairbanks, 1980) General Discussion {fires are set} almost every day throughout the year in some part or other, by the Indians, for the purpose of raising the game, as also by the lightning. (Bartram, 1791, along the St. Johns River, Florida, p. 139.) Evidence concerning the longleaf and sand pine communities on the study area can be summarized as follows: 1. The pollen record indicates that pine has predominated over the last 5000 years after succeeding oak and grass (Watts, 1969). The species of pine(s) is not known

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80 2. The present longleaf and sand pine communities differ in species composition, physiognomy, and relationship to fire. The longleaf community is similar to those occurring elsewhere on sandy uplands; the sand pine-scrub appears unique to central Florida and some coastal areas. 3. These two communities coexist, separated by boundaries that are (or were) remarkably well-defined and abrupt. These boundaries have been stable for at least the last 150 years (General Land Office Surveys, 1820-1860) and even when overrun by sand pine and oak their former positions are still evident. 4. Except where surface horizons have been darkened under longleaf pine, boundaries between the two communities do not coincide with any differences in soil physical or chemical properties within the upper 5 m depth (Tables 1-3, 1-4, 1-5, 1-6; Figs. 1-5, 1-8, I-IO). Rather, boundaries transect a variety of profile types and substrates. 5. The two communities appear to differ in annual acc\amulation rates of biogenic opal in soils. Soil (0-60 cm) opal contents are markedly higher under longleaf pine locations remote from present boundaries. In contrast, soils from paired longleaf and sand pine plots only 200 m apart do not always differ appreciably in total opal contents (Table I-IO; Fig. I-ll) They do differ, however, in abundance of dumbbell-shaped phytoliths and diatom

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81 frustules (Table I-lO) two opaline forms diagnostic of occupancy by the longleaf pine community. 6. Schematic isolines of total opal contents of soils (0-60 cm) are grossly concentric about core areas of islands, but do not necessarily conform to present island boundaries (Fig. 1-14) This concentricity suggests that island boundaries have expanded and contracted irregularly in the past. The most recent prehistoric changes were sufficiently long ago that diagnostic opal forms are no longer identifiable on some areas that may have been occupied by the longleaf pine community. 7. The extensive sand pine forest of the Ocala National Forest probably owes its existence to a nearly continuous firebreak of rivers, lakes, and wetlands (Fig. I-l) that has excluded all but the greatest conflagrations originating outside the area. The longleaf pine islands, like longleaf communities elsewhere, could only have been maintained by fires at intervals of 1-5 years (Harper, 1914b; Christensen, 1981) Annual ignition by lightning strikes during the 19 70 to 19 81 period averaged only 1.7 per 10,000 ha on the forest (S. Holscher, Fire Control Officer, Ocala N.F., personal communication, 1982) This is far too infrequent to provide the necessary regularity of burning on isolated islands as small as 60 to 500 ha.

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82 8. Repeated burning was a general practice among Indians of the historic period (Bartram, 1791; Heizer, 1956) and apparently had been for long periods in the past. Archeological history demonstrates the presence of man in the Ocala area for at least as long as pine forests have predominated (Milanich and Fairbanks, 19 80) and specific evidence shows his presence on or immediately adjacent to longleaf pine islands (Table 1-12) The totality of this evidence leads to the hypothesis that the longleaf pine islands were maintained through annual or frequent burning by early man: longleaf pine islands are therefore human artefacts. This hypothesis requires that fires be restricted to the longleaf pine community rather than burning the surrounding scrub or sand pine with equal frequency. Such restriction is provided by the contrasting fuels of the two communities. Wiregrass and pine litter burn readily when dry, whereas the evergreen sand pine-scrub has been called a "fire-fighting machine" (Webber, 19 35) because of its non-f lammabili ty under normal weather conditions. Once established, boundaries between the two could remain stable under a regime of frequent ground fires on the islands Despite this difference in fuels, events of the past century leave no doubt about fire occurrence in sand pinescrub, or scrub alone, and the high intensity of such fires.

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83 Variations in climate and human use over the past millenia almost certainly determined fire frequency in longleaf and sand pine. Such differential burning seems the most likely agent causing expansion or contraction of island boundaries Maintenance of boundaries by Indian fires nevertheless leaves the question of origin unanswered. It is likely to remain a wholly speculative matter unless future distinction between longleaf and sand pine pollen in the fossil record may indicate which, if either, predominated 5000 years ago when pine replaced oak and grass in the region In any case, the relationship of longleaf pine islands to fire and man is similar to that of numerous other communities, including oak woodlands in the Northeast (Day, 1953) ; montane pine forests in the Philippines (Kowal, 1966); and perhaps prairies worldwide (Sauer, 1950; Stewart, 1953) and "caatinga" scrub in Amazonia (Anderson, 1981) In all such cases, the juxtaposition of contrasting plant communities is explainable only in light of the central role of fire, and man as the agent of ignition.

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CHAPTER II SOIL MIXING BY ANIMALS IN THE LONGLEAF PINE AND SAND PINE COMMUNITIES A diversity of animals inhabit the soil and affect its properties in various ways (Hole, 19 81) In temperate regions, the emphasis has been on animal mixing within the upper 60 to 100 cm layer of soil, as by ants (Baxter and Hole, 1967; Lyford, 1963) earthworms (Buntley and Papendick, 1960) and small mammals (Abaturov, 1972) Deeper soil mixing has been reported for crayfish in Louisiana (to 4.5 m; Thorp, 1949), harvester ants in South Carolina (to 2.2 m; Gentry and Stiritz, 1972) and gopher tortoises in Florida (to 2.8 m; Hansen, 196 3) Burrowing by such animals destroys stratification and homogenizes the soil to some depth. This paper reports especially on deep tunnelling and soil mixing by a scarab beetle of east-central Florida, Peltotrupes young i Howden, and on the relationship of beetle activity to vegetation type and abundance. Collateral information is also presented on the extent of soil mixing by pocket gophers ( Geomys pinetus ) which often occurred in the same study areas. The Beetle The genus Peltotrupes is included in the tribe Geotrupini (Coleoptera: Scarabaeidae) along with two 84

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85 other soil-inhabiting genera. Geotrupes occurs in mesic, temperate regions throughout the world, and constructs tunnels less than 1 m deep. The flightless genus Mycotrupes is confined to the coastal plain of the southeastern U.S., and tunnels to depths of 2 m (Woodruff, 19 73) Species of Peltotrupes are metallic, robust scarab beetles, about 20 mm long and 16 mm wide, that occur as disjunct populations in Florida. The population occurring in the Ocala National Forest in Marion and Putnam counties is recognized as the species P. youngi (Woodruff, 19 7 3) Suitable habitats are well-drained sandy soils vegetated with either sand pine ( Pinus clausa ) -scrub, or longleaf pine-turkey oak (P. palustris Quercus laevis) Adult beetles emerge from November onward and are active until April. Burrows are constructed through the joint effort of a male and female (Fig. II-l) The burrow enters the soil at a slight angle, then continues vertically downward to an enlarged larval chamber (Young, 19 50; Howden, 19 52) The excavated soil is pushed up to form a surface mound, and some unknown quantity of surface litter is transported down to the chamber where the female deposits her eggs. Larvae feed either on the litter or on fungi that grow on the litter, and presumably complete development in one year (R, E. Woodruff, personal communication, 1981) Materials and Methods This study was conducted on the Lake George Ranger District of the Ocala National Forest in east-central Florida.

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Figure II-l. Burrow of Peltotrupes youngi (Based partially on data in Young, 1950, and Howden, 1952.)

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87 Surface Mound 600 g Burrow of Peltotrupes youngi Tunnel 2 cm. X 120 to 360 cm. Larval Chamber 5x15 cm.

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88 The soils are classified as the hyperthermic, uncoated families of Spodic and Typic Quartzipsamraents These are well-to excessively-drained sands with less than 5% silt plus clay in the upper 2 m layer. Below 2 m, however, texture and stratification are variable. The two plant communities of interest are sand pinescrub and longleaf pineturkey oak. These communities differ markedly in physiognomy and species composition. Scrub is an unique understory of evergreen shrubs, dwarf palms, and small trees. The chief species are myrtle oak ( Quercus myrtifolia ) sand live oak (Q. geminata ) Chapman's oak (Q. chapmanii ) crookedwood (Lyonia f erruginea ) scrub palm ( Sabal etonia) and saw palmetto ( Serenoa repens ) Density and height of scrub vary greatly. In contrast, longleaf pine occurs as an open parkland with a groundcover of wiregrass (Aristida sp ) and a diverse herbaceous flora (Harlow and Bielling, 1961) On sites where longleaf pine has not regenerated, turkey oak now dominates, with a much less abundant grass and forb flora. Beetle activity was monitored in the 1980-81 and 19 81-82 seasons on permanent sample plots in four vegetation categories: sand pine with thick scrub, sand pine with thin scrub, longleaf pine with thick grass, and longleaf pine with thin grass (Table II-l) Five study areas were selected in each category. Within each study area, a 5 m wide by 200 m long transect was installed along a randomly

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89 Table II-l, Selected characteristics (mean S.D., n=5) of four vegetation categories: sand pine (SP) with thick and thin scrub; longleaf pine (LLP) with thick and thin grass. Category Basal Area"*" m2/ha Mass mt/ha Scrub Sand Pine Forest Floor SP-thick SP-thin 2.9 0.8 0.3 0.5 17.8 5.1 18.7 2.0 31.4 5.2 19.8 5.5 LLP -thick LLP-thin Turkey Oak 0.1 0.2 7.7 1.5 Longleaf Pine 10.5 3.0 3.4 2.4 Grass 1.4 0.5 0.2 0.0 Litter 3.6 1.0 3.9 1.4 '^Sterns >_2 cm dbh. J, '"Ash-f ree

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90 chosen compass line. Beetle mounds were counted on three 20 X 5 m plots centered on the 10, 100, and 190 m points of these transects. In the 19 80-81 season, mounds were counted two to three times per month, from January through April, on one area of each category to determine the seasonal pattern of mound building. After beetle activity ended, total numbers of mounds constructed since November were counted on each of the 15 plots per category. In 1982, a single count was made in April. Mounds made during the 1981-82 season were easily recognized since those of the previous season were largely obliterated by rain and litter deposition. Total mound numbers for the three plots per area were averaged for analysis, giving five replicates for each vegetation category in each year. The data were log-transformed to correct for correlation between means and variances, and subjected to ANOVA. Mounds made by pocket gophers were counted and marked on each entire 200 x 5 m transect in April, 1981. A parallel count in April, 1982, provided an estimate of mound construction during the intervening year. Soil samples were collected at two sand pine sites which had higher nutrient contents below 50-100 cm than in the surface, and which had been newly invaded by beetles. Each pair of samples consisted of a) the entire mound, and b) a composite of six 2.5 cm-diameter cores from the

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91 upper 10 cm depth, distributed around a 15 cm radius centered on the mound. These samples were analysed for extractable nutrients by the double-acid procedure (Mitchell and Rhue, 19 79) Results and Discussion Soil Movement by Peltotrupes youngi In 1980-81, the first beetle mounds appeared in mid-November. Mound numbers in the three vegetation categories with significant beetle activity then rose gradually, and tapered off by mid-March as shown below: Cumulative % of total mounds present on date specified Jan. 6 Jan. 15 Feb. 20 Mar. 24 Apr. 8 SP-thin 28 59 69 97 97 LLPthick 17 33 58 89 98 LLP -thin 28 34 60 95 100 The temporal pattern of mound building was similar during the 1981-82 season. Peltotrupes youngi larval chambers have never been found at depths less than 1 m (Young et al 1955), whereas the maximum depth previously recorded was 3 m (Woodruff, 1973) Greater maximum depths were observed during the course of the present study on an area where a white (lOYR 8/1) subsoil layer contrasted sharply with the yellowish brown (lOYR 6/4) sand above. It thus served as a marker of penetration when found at the top of beetle

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mounds. Borings adjacent to mounds so marked gave minimum burrowing depths ranging from 3.6 m on the crest, to 2.4 m near the base of a 100 m, 8% slope. Since the white layer averaged 7 5 cm thick, some burrows may have exceeded 4 m in depth. Likewise, numerous observations of small bits of charcoal and organic materials deep in the soil suggest that P. youngi may burrow to depths of 5 m. Mounds collected from a variety of sites averaged 630 + 161 g (mean + S.D., n=20) air-dry. The average mass cannot account for the calculated total volume removed in excavating a burrow system. The remainder is unaccounted for, but it is possible that it is disposed of in old tunnels, root channels, and other voids encountered by beetles during burrow construction. Numbers of beetle mounds on 19 individual sites did not differ significantly between the two seasons of measurement (Fig. II-2) On two LLP-thin sites that were disturbed in the early winter of 19 81, however, mound numbers increased markedly. The increase was 60% on a shelterwood-cut area ("C" on Fig. II-2) and 170% on an area that was prescribedburned ("3" on Fig. II-2) Similarly, rapid responses to reduced ground cover density occurred in a SP-thin stand that was burned by a wildfire in February, 19 80. Two weeks after the fire, mound density on the burned area was nearly double that on the adjacent unburned portion of the stand, 2400 + 610 vs. 1400 + 281 mounds/ha (mean + S.D.; n=10)

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Figure II-2. Comparison of the number of beetle mounds counted on twenty-one 300 m^ plots in 19 81 and 1982. Site "B" was burned, and site "C" was logged between the two counts. (r2 = 0.90, excluding the two disturbed sites )

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400• SAND PINE A LONGLEAF PINE 300GO (J) in 1 00 200 NUMBER OF MOUNDS, 198!

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95 Table II-2 summarizes the association of beetle activity with vegetation type and density. Mounds were significantly fewer on SP-thick sites, and significantly more numerous on LLP-thin sites than on any SP sites. The greatest density observed was 13,000 mounds/ha on one LLP-thin site. This is equivalent to 7 8 mt/ha/yr of subsoil deposited on the surface as mounds, which is similar in magnitude to annual production of earthworm casts on favorable sites in temperate regions (Edwards and Lofty, 19 77) High mound densities are not artefacts of small sample plot size; the 13,000 mounds/ha density noted above occurred over an area larger than 4 ha. Lower numbers of mounds in thick vs. thin scrub, and in thick vs. thin grass are apparently due to obstruction of the beetles' flying and scavenging activities. Beetle mounds occurred on only one of the five SP-thick study areas. This was adjacent to a LLP stand, and P. young i penetrated into the scrub along a partially overgrown trail. Soil Movement by Other Animals Pocket gophers burrow primarily in the upper 60 cm. Excavated soil is deposited on the surface in mounds that range from less than 10 to almost 100 kg in mass. The sequence of construction of tunnels, burial of surface litter under mounds, and collapse of tunnels represents a churning and homogenization of the surface soil. This type of mixing contrasts with the deep, essentially one-dimensional, mixing of P. youngi

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96 Table II-2. Average number of mounds and total amount of soil deposited annually (two-year average for Peltotrupes beetles, one-year values for pocket gophers, n=5) Pocket Beetle Mounds* Gopher Mounds Vegetation Category no./ha/yr kg/ha/yr no./ha/yr kg/ha/yr SP-thick 33 a 20 0 a 0 SP-thin 973 b 580 0 a Q LLP-thick 2513 be 1510 558 c 8160 LLP-thin 6163 c 3700 20 b 290 'Within a column, means not followed by the same letter are significantly different at a=0.05.

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97 Although spatially and temporally variable, soil disturbance by pocket gopher activity is great on suitable sites. An average of 8.2 mt/ha/yr of soil was deposited in mounds on the five LLP-thick sites (Table II-2) Much greater activity was observed on other LLP areas. On a recently burned, 2 ha LLP-thick site, remote from the study areas, pocket gopher mounds exceeded 2 50 0/ha and 37.5 mt/ha, covering approximately 4% of the surface. Pocket gophers were much more abundant on LLP-thick than on LLP-thin sites, and were totally absent from SP sites (Table II-2) This pattern is presumably a response to the abundant food provided by the rich herbaceous flora of LLP-thick sites, in constrast to a lesser abundance on LLP-thin sites, and absence under SP. In general, burrowing soil animals occur in reduced numbers or are absent from SP as compared to LLP areas (Harper, 1914a). Both the Florida harvester ant ( Pogonomyrmex badius; Van Pelt 19 56) and the burrowing oldfield mouse ( Peromyscus polionotus ) are found throughout the LLP type, but are common in SP only after major disturbance. Similarly, the gopher tortoise ( Gopherus polyphemus ) is widely distributed in LLP, present in low numbers in the early successional stages of SP, and absent from mature SP (Hansen, 196 3) Thus, differences in the physiognomy and species composition of the two plant communities produce different soil animal assemblages and extent of soil mixing.

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98 Effects of Mixing on Soil Properties Table II-3 illustrates upward transport of nutrients by beetles that had opportunistically moved into two SP sites from which they are normally absent. At location 1 they had entered a SP clearcut; at location 2 they had followed a trail into a thick scrub. Although the absolute quantity of nutrients brought to the surface is not large, flattened mounds represent point deposits of more fertile soil and hence more favorable micro-sites. Such differences would be obliterated, of course, if beetles were to remain active on these sites over long periods. Surface texture is also modified by beetle mounding on certain sites. Beetles penetrate layers at least as fine as sandy loam, and hence may bring clay particles to the sandy surface. Flattened quartzite pebbles as large as 1.5 cm in diameter and 1.5 g in mass are brought up from depths exceeding 2 m, again influencing surface texture. Although beetles may alter surface soils wherever subsoil layers are chemically or physically different than the surface horizon, much of the area is uniform to depths greater than 5 m. On such sites upward transport serves only to counter leaching of the surface layer and retard horizon development. Bulk densities of these sands often reach 1.7 to 1.9 g/cm at 6 0 cm and below, presenting substantial impedence to root development (Taylor et al., 1966). Yet

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99 Table II-3. Extractable element concentrations in Peltotrupes beetle mounds compared with adjacent 0-10 cm soil layers/ Location and Nutrient #1 (n=15) Ca + Mg (me/100 g) P (ppm) #2 (n=5) Ca + Mg (me/100 g) P (ppm) Concentration Mound Soil 0.2 0.2 12.3 ** 2.5 0.2 0.1 1.5 0.9 See text for description of locations. **Dif ference between values for mound and surface soil are significant at 0.05 and 0.01 levels, respectively, by paired t-test.

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100 SP roots regularly penetrate to depths of 2 to 4 m, and LLP to even greater depths. Field observations suggest that the vertical tunnels of P. youngi provide open or low resistance channels for penetration of tap and sinker roots The soils under SP on the Ocala National Forest form a continuum from Spodic Quartzipsamments with thick bleached albic horizons, to Typic Quartzipsamments with only minimal surface horizon development. Most LLP soils are also Typic Quartzipsamments, but were separated as a dark surface phase due to the presence of a 20 to 50 cm thick A horizon (Aydelott et al 1975). In most cases, thick scrubs prove to be associated with Spodic Quartzipsamments having albic horizons, and thin scrubs with Typic Quartzipsamments. The relationship between thick scrubs with bleached surface layers and low populations of soil mixing animals is not directly causal. Rather, eluviation seems to be causally related to greater shrub density and litter productivity (Table II-l) which in turn results in habitats unfavorable to these animals (Table II-2) Hence there is little soil mixing to retard eluviation. In contrast, longleaf pine sites are typical grasslands in that incorporation of litter and surface soil homogenization are dominant processes. The combination of frequent fires, a rich herbaceous flora, and an active soil fauna produces a thick, dark surface horizon. Such surfaces are not found on any SP sites.

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101 Thus, P. youngi is an important mixing agent that burrows to 360 cm or deeper on suitable sites and can tran port as much as 8 mt of subsoil to the surface per hectare per year. In doing so it leaves behind open or low density channels that serve as root pathways in an otherwise dense medium. in association with other soil animals, it influences the course of soil genesis and hence profile morphology.

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APPENDIX I SCIENTIFIC NAMES OF SPECIES CITED Andropogon sp. L. Aristida striata Michaux. Asimina sp. Adanson Ceano thus microphyllus Michaux Diospyros virginiana L. Eupatoriiim sp. L. Ilex opaca L. var arenicola (Ashe) Ashe Licania michauxii Prance. Lyonia ferruginea (Walt.) Nutt. Pinus clausa (Chapm.) Vasey. Pinus elliotti var. elliottii Engelm. Pinus palustris Mill. Pteridium aquiTinum (L ) Kuhn. Quercus chapmanii Sarg. Quercus gemma ta Small. Quercus incana Bartr. Quercus laevis Walt. Quercus myrtifolia Willd. Sabal e tenia Swingle Sabal palmetto (Walt.) Lodd. Serenoa repens (Bartr.) Small Yucca filimentosa L. Broomsedge Wiregrass Pawpaw Redroot Persimmon Dogf ennel Scrub Holly Gopher Apple Crookedwood Sand Pine Slash Pine Longleaf Pine Bracken Chapman s Oak Sand Live Oak Bluejack Oak Turkey Oak Myrtle Oak Scrub Palm Cabbaga Palm Saw Palmetto Bear Grass 102

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APPENDIX II LOCATION AND PARTIAL CHARACTERIZATION OF THE PAOLA SERIES PROFILES EXAMINED IN THIS STUDY

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4-) ^ (1) j= M 4-1 e M d -H O (U 03 0) Q (1) a fa CO o in in o ^ m cn ^ ^ ^ ^ ^ o o o o 00 o in o oj n (N o o o in o o in ! 0) *i I 0) c •H fa !h +J (T3 0) fa rH CN O CT> CN in rH rH ro CN ^ ro • W fa fa W H fa W in vD in in in ^ CN CN CN CN fN CN rvj • CtJ K cr; K • CO CO CO CO CO CO • CO T in ^ in •-t r-{ r-i t-1 i-i i-\ 1^ irt ir< • Eh ro rH in ^ :r r-{ i-i Cn (Si r-t in O O 0 O CJ O O CU (U
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APPENDIX III DETERfllNATION OF ORGANIC MATTER BY THREE STANDARD OXIDATION PROCEDURES xMethod I Samples were oven-dried at 105oc, then ignited at 500oc in a muffle furnance for 12 hours. Organic matter was estimated as the percentage of the ovendried sample lost during ignition. Method II Organic carbon in air-dry samples was determined using a Leco high temperature induction furnace. Results were converted to organic matter using the conventional factor 1.72, and expressed as percentages on an oven-dry basis. Method III Organic carbon in air-dry samples was determined by wet oxidation using dichromate according to the Walkley-Black procedure (Jackson, 1958) Flasks were warmed prior to the addition of H2S0^, and were placed on heat-resisting pads during the reaction. Solution temperature during mixing was 110 to 120C. Carbon values were corrected for oxidation efficiency with the factor 1.3 (Dyal and Drosdoff, 1941), and converted to organic matter using the conventional factor 1,72. Results are expressed as percentages on an oven-dry basis. All analyses were performed in duplicate. Sample weights were 3 to 5, 0.2 to 0.5, and 1.0 to 1.5 g for Methods I, II, and III, respectively. 105

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106 Method II oxidizes less than 5% of wood charcoal mixed with soil (Bremner and Jenkinson, 1960) ; hence, this method measures organic matter only. Methods I and II oxidize organic matter and charcoal. In addition. Method I removes lattice water from clay minerals. Charcoal in soils can therefore theoretically be estimated as: 1) Method I, corrected for lattice water lost during ignition ("Corr. I"), minus Method III; 2) Method II minus Method III. The results in the following table suggest: 1) charcoal contents are too low to be detected by the relatively crude methods employed; or, 2) Method III actually accounts for significant amounts of charcoal and/or charcoal oxidation is incomplete using Method II. in addition. Method I, corrected values, are undoubtably too low since the clay fraction includes non-kaolini tic components with much less that 14% lattice water.

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107 Sample JXyctIlXC^ ilduL-SX ^ -6 ; Dy jMetnou T X (^r\-y -v* T T OXi 1 X T T X X III 6 T T D n — 1 n u ~u 4 1 J *i n J u J Z 2 7 9 n ^ u 0 9 c n (: n X • o n Q u y n Q u y T A 0 QP Dxr n — T n u xu X D X D o n Z U 1 n 9 n xu — ZU X u n 7 u / n Q U o 1 A X 0 jU — oU U n /I U 4 n c U D 7 n In U — XU X • o X.J X b 1 O X.J 1 n X u 1 n X U 1 1 7 bP 0-10 X.I X X 1 0 1 J 1 5 10-20 n c U D n "3 U.J A n 0 5 0 6 o T T Ti 0-10 0 1 ^ X X b A A 2 2 2 5 a oP n In U XU 0 0 X y O A 2 0 A A 2 2 Q -7 T T T> LlLlP n In 0-iO X 0 X D 1 4 1 4 q bP n in U-10 X / 1 J 1 4 1 5 1 n LLP A T A 0-10 o n A "7 2 7 2 .9 C A ^ A n c U D ^ n 1 < U 1 A A 0 3 0 3 1 n CD of U — lU 1 7 X / 1 J 1 6 1 7 C A A 50-50 n U b n o 0 J 0 2 0 3 11 -I. JL LLP 0-10 X.J 1 n X 0 T A 1 4 11 SP 0-10 1 7 X / 1 A X 4 1 A 1 9 1 2 LLP 0-10 0 A o n Z 0 1 A 1 9 1 9 50-60 0 8 0.4 0 3 0.3 12 SP 0-10 1.4 1 1 1 5 1 6 X • U 50-60 0.6 0.3 0.2 0 2 13 LLP 0-10 2.2 1.9 2.1 2.1 13 SP 0-10 1.9 1.8 1.6 1.8 14 LLP 0-10 2.0 1.6 1.7 1.8 14 SP 0-10 0 8 0.4 0 8 0.9 15 LLP 0-10 1.4 0 8 1.3 1.2 15 SP 0-10 1.3 0.9 1.4 1.4 Pair No.; LLP = longleaf pine, SP = sand pine; depth in cm. "^Method I, corrected for loss of lattice water. Assumptions: 1) clay contents are 80% of the amounts of silt plus clay given in Appendix V; 2) clay is kaolinitic, with 14% (w/w) lattice water lost above 100C (after Dyal and Drosdoff, 1941)

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APPENDIX IV LOCATIONS OF 15 PAIRED PLOTS (SAMPLE POPULATION II) AND 60 ADDITIONAL SITES SAMPLED FOR BIOGENIC OPAL (SAMPLE POPULATION III)+ Paired Plots 1. Riverside Isl. 0.8 mi. S. of FR-75 along W. boundary, 2. Riverside Isl. 0.3 mi. N. of FR-75 along E. boundary above L. Delancey. ^ 3. Salt Springs Isl. 0.45 mi. S.W. of FR-88 on FR-50 along N.W. boundary. 4. Salt Springs Isl. 1.0 mi. E. of FR-88 along S. boundary. 5. Hughes Isl. On FR-lOA along N. boundary. 0.85 mi W. of unnumbered road leading to FR-86 ^' l^^l 1-45 mi. N.E. on FR-IOC from FR-10 along N. boundary. ^ 7. Norwalk Isl. 2.2 mi. W. of SR-19 on FR-47 alonq S.W. boundary. ^' fo^^n^P""-!?^^ 0-3 mi. S. of Los Haven Chapel and SR-il4. Sand pine island" on Salt Springs Island. 9. Kerr Isl. 0.4 mi. W. of FR-88 on FR-63 alonq S. boundary. 10 Riverside Isl. 60 m S. of #1 along W. boundary 11. Riverside Isl. 0.1 mi. E. of FR-88 along S.W boundary. N. of Grassy Pond. 12 Salt Springs Isl. 1.0 mi. w. of FR-88 on FR-50 alonq S.W, boundary. All road distances were measured in miles by odometer readings; other distances were paced in meters. Abbreviations are: C = county road; FR = forest road; SR = state road; LLP = longleaf pine site; SP = sand pine S 1 uG • 108

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109 13. Norwalk Isl. 0.4 mi. E. of SR-19 from a point 2.0 mi. S. of FR-7 5. Along S.E. boundary. 14. Hughes Is. 0.4 mi. E. of #5 on FR-IOA. 15. Riverside Isl. 0.25 mi. N. of FR-77 along W. boundary. Near Penners Ponds. Sample Population III 1. E. side C-301, 2 mi. S. FR-301; SP 2. E. side C-301, 0.7 mi. N. FR-75, at clay pit; island #1, Table 1-12; LLP. 3. E. side C-301, 1.45 mi. N. FR-75; island #1, Table I12; LLP. 4. E. side C-301, 2.15 mi. N. FR-75; SP. 5. S. side FR-75, 2.4 mi. E. C-301; SP 6. S. side FR-75, 2.3 mi. E. FR-97; SP; Site 2 on Table I-ll. 7. N. side FR-31, W. boundary of Riverside Isl.; LLP. 8. N.W. quadrant, junction FR-31 and FR-88; LLP. 9. W. side FR-88, 0.5 mi. S. of Ocala Seed Orchard; SP; Site 1 of Table I-ll. 10. E. side FR-88, 0.5 mi. N. Ocala Seed Orchard; Riverside Isl.; LLP. 11. E. side SR-19, 0.75 mi. S. FR-75; Norwalk Isl.; LLP. 12. E. side FR-48, 0.75 mi. S. FR-47; Syracuse Isl.; LLP. 13. W. side SR-19, 0.75 mi. S. FR-47; SP 14. E. side FR-65, 0.75 mi. S. SR-19; Salt Springs Isl.; LLP 15. N.W. from FR-46 on FR-77 0.4 mi., then W. 0 7 mi ; SP. 16. N. from FR-75 on FR-46 1.1 mi., then W. 0.75 mi.; SP 17. S.E. quadrant, junction SR-314 and FR-97; SP

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110 18. S. side SR-314, 0.3 mi. E. of W. boundary; Salt Springs Isl.; LLP. 19. E. side FR-88, 0.9 mi. S. FR-90; SP. 20. S.E. quadrant, junction FR-88 and FR-10; SP 21. S.E. on FR-lOB from FR-10 0.95 mi.; then S. 0.2 mi. to "T", then E. 0.3 mi.; SP 22. S.E. quadrant, junction FR-10 and FR-lOB; SP 23. S. side FR-10, 1.15 mi. E, of FR-65; SP. 24. N. side FR-10, 0.9 mi. E. of W. boundary of Pats Isl. LLP. 25. N. side FR-10, 0.15 mi. E. of E. boundary of Pats Isl SP. 26. N. side FR-86, 1.2 mi. W. of SR-19 ; SP 27. E. side FR-65, 0.25 mi. S. FR-90; SP 28. E. 0.3 mi. from FR-88 on small road just S. of junction with SR-314; Salt Springs Isl.; LLP. 29. S.E. quadrant, junction FR-10 and FR-65; SP 30. N. side FR-10, 0.15 mi. W. of E. boundary Pats Isl.; LLP 31. N.W. quadrant, junction FR-10 and SR-19; SP 32. W. side FR-88, 0.3 mi. N. of FR-50 between Salt Springs and Kerr Isl.; SP. 33. W. side FR-88, 0.4 mi. S. FR-63 between Salt Springs and Kerr Isl.; SP. 34. W. side FR-88, 0 1 mi S. SR-316; Kerr Isl.; LLP. 35. E. side FR-88, 1.45 mi. N. SR-314; Salt Springs Isl.; LLP. 36. E. side FR-88, 0.3 mi. N. SR-316; SP 37. S.E. quadrant, junction FR-88 and FR-88C near Grassy Pond; SP.

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Ill 38. E. 1.75 mi. from Ocala Seed Orchard to E. boundaryRiverside Isl., then E. 0 3 mi ; SP 39. E. side FR-88, 0.5 mi. S. FR-75; Riverside Isl.; LLP. 40. E. side FR-88, 1.05 mi. S. FR-75; Riverside Isl.; LLP. 41. E. from #40 1.15 mi. to road junction; N.E. quadrant; Riverside Isl.; LLP. 42. W. side FR-88. 0.4 mi. N. FR-75; Riverside Isl.; LLP. 43. W. side FR-88, 1,4 mi. N. FR-75; Riverside Isl.; LLP. 44. N. side FR-31, 0.8 mi. W. of W. boundary of Riverside Isl.; SP. 45. S. side FR-75, 1.1 mi. E. FR-97; SP. 46. W. side FR-9 7, 1.0 mi. S. FR-75; SP 47. W. side FR-88, 0.1 mi. N. of entrance to Moorehead Park; Kerr Isl.; LLP. 48. E. on SR-314, 1.2 mi. from FR-88, then N. 0.1 mi.; Salt Springs Isl.; LLP. 49. W. side FR-61, 1.0 mi. N. FR-97; SP. 50. E. on FR-10, 0.35 mi. from W. boundary of Hughes Isl., then N. 500 m; LLP. 51. E. 50 m from sinkhole pond on Hughes Isl., at trail junction; LLP. 52. N. on FR-10 A 0.8 mi. from FR-10 at E. boundary of Hughes Isl., then N.E. 0.3 mi. on woods road; SP 53. W. side FR-lOA, 0.45 mi. S of junction with woods road in #52; Hughes Isl.; LLP. 54. S. side FR-10 0.75 mi. E. FR-65; SP 55. S. side FR-10, 0.3 mi. W. of junction with FR-IOC on W. boundary of Pats Isl.; SP 56. N. on FR-IOC, 0.35 mi. from FR-10 on W. boundary of Pats Isl., then N.W. 0 2 mi ; SP 57. S. side FR-10, just E. of W. boundary of Pats Isl.; LLP.

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112 58. N. side of sinkhole in center of Pats Isl.; LLP. 59. N. side FR-IOC, 0.3 mi. S. of FR-10 along S.E. boundary of Pats Isl.; LLP. 60. S. side FR-10, 0.3 mi. E. FR-88; SP

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APPENDIX V SUMMARY OF CHEMICAL AND PHYSICAL CHARACTERISTICS OF PAIRED LONGLEAF PINE (LLP) AND SAND PINE (SP) BOUNDARY PLOTS

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u u > u H H iH V in 00 CO in (x> 1 Eh CU CU CU lA •H OS C hi w Ui rH rH CM CN n in in CM 1^ o o n ro ro ro ro "d* in o CM ro in 'd' CO in in T ro V V V + dfi in ro 00 ro CM H ro CM ro ^ ro o CM rH rH •H rH o o o o o o O o O O o o o o O O o o O o o in o o CM O o CM O o O rH o O o CM 00 O M e a o 1 00 1 in 1 ro 1 in 1 00 1 CM 1 1 in rin 00 rH CM ro in ro in in 0) — o o o o o o o o 1 o 1 o 1 o 1 o 1 o 1 O 1 o 1 1 o o 1 o 1 o 1 o 1 o 1 o 1 o Q in 00 CM rM CO ^ o H o CM 00 ro ro (N '3' rH rvj ro ro 'J' ro ft ro ro W3 o ro CU 114

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115 U U + (jP H to Q H .H H V r-l *1< ^^^ ro Tj< n rH CM in in v£> t~CO ro iH iH o V V O iH 0 o o (N 00 O ro ^ in 1 I I o o o (N 00 H CM in iH iH H rH O O n in CM '3' rH CM o o o o O fH CN T O vD CN n ro in I I I I I o o o o o ix> n^ CM o^ ini^r^T'^'roin^ ooror-ro in'*o ^orooo Tji CM Eh ^^ u Ui •H n as C in in Pi4 (0 rH iH CN V V (N CM ro O O O in in o ro in t I t o o o in in ro 'd" cri CN CM o o CO rH rH rH O O V V V CM rH 0 o o o o o in o c o ro ro "tr ^ in 1 I I I I o o o o o o in o 00 ro ro ^ ro o CN o in ro o

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116 u > u + (*5 C/3 Q e ft ft •
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117 (0 -P o (0 -p w > fa U u + dC •H -M S a O Q 6 a tn CO 0) o w o (0 iH m \ (U s o cTi o rin vD v£5 in VD CTi 00 00 V V in CO V V V r-J O V V ro in in rV V V o o (N o o o rH rH V V 0 a Eh U •H la (0 c rH rH rH rH in rH (N
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118 > c CO U C/3 (1) w Q CO (1) o CQ O m v e • (D o a Eh rH O C CO (0 in 'i •4-) e c rrl u in i vo O 0) 0,0 .H • o -P 0) o Qi Sh OJ 1 (0 c/3 in ^ T3 M o 00 4J CO n3 • IT) n c 0 o 0 O — n 4J •H -p II 0) u C — e (13 U -H S-( 4-1 CO o m >i O (U H x: c IT3 > 0) CO fN u o to fa -H > CO 0) S (0 CO — + (X X5 5h -X CO n n3 ^ HOE U •H U ft 0 in (U CO >|(N Sh • o o nj rH (U II in 0 -H 1 1 > -P x: II • o o n3 CJ S o 03 U ^ (C3 > i +J C in rH C (t3 II m Q) CO -a O fa 4J (1) U (U rH (1) QJ • (1) 0 rH rCO rH m s iH Q) rH 1 i 5h 0 in (t3 (C3 in rr 0) rH rH o o U O U O • • CO 1 to x; + 'D in iH 4J C CN P ra • o o H O • • 6 73 •H 1 ^ CO -P c e rH e II -H 13 m -H 3 o rH T! 0 o U 0)
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APPENDIX VI BIOGENIC OPAL CONTENTS OF 6 0 SOILS FROM SAMPLE POPULATION III Opal Opal mt/ha/60 cm o X L.e g. o mt/na/oU cm 1 X u u ^ o /. 4 3i 0.018 1 6 n n 7 vj U -J 0 J D 3 2 0.019 1 7 J n n 9 9 X.J J J r\ n o n 1 o A *t U • U X ** X o "5 A U 0 lb 1 4 i; n n n 7 U 0 "5 c: J D U 0 J / J 4 c D n n 9 n 1 O "5 C JO f\ n o o 0 0 z z 2 0 7 U • U O X J / A r\ T "7 0.01/ 1 5 o o n 0 4 p U • U T 0 A A T Q J O 0.014 1 3 q u • u z o 0 1 Z X "5 Q jy 0.015 1 4 U • U X A n 4 (J 0 0 1 J 1 2 X X n 0^9 0 Q 4i 0.035 3 2 X 4. n 0^9 2.9 4 z 0.012 1 1 13 0 .009 0.8 43 0 .075 6.8 14 0 .036 3 3 44 0.020 1.8 15 0 .019 1.7 45 0 014 X.J 16 0 .007 0.6 46 0 .010 0.9 17 0.005 0.5 47 0 .006 0.5 18 0.016 1.5 48 0 .013 1.2 19 0 .014 1.3 49 0 .043 3.9 20 0.008 0.7 50 0 .020 1.8 21 0.020 1.8 51 0.057 5.2 22 0 .060 5.5 52 0.053 4.8 23 0 .015 1.4 53 0 .026 2.4 24 0.174 15.9 54 0 .016 1.5 25 0.068 6.2 55 0 .030 2.7 26 0 .036 3.3 56 0 .066 6.0 27 0.031 2.8 57 0 .084 7.7 23 0 .018 1.6 58 0.144 13.1 29 0.031 2.8 59 0.055 5.0 30 0.050 4.6 60 0 .020 1.8 119

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LITERATURE CITED Abaturov, B. D. 1972. The role of burrowing animals in the transport of mineral substances in the soil. Pedobiologia 12: 261-266. Alt, D., and H. K. Brooks. 1965. Age of Florida marine terraces. J. Geol. 73: 406-411. Anderson, A. B. 1981. White-sand vegetation of Brazilian Amazonia. Biotropica 13: 199-210. Aydelott, D. G. 1966. Soil management report, Ocala National Forest, Florida. USDA For. Serv., South. Region, Atlanta, Ga. Aydelott, D. G., H. C. Bullock, A. L. Furman, H. 0. White, and J. W. Spieth. 1975. Soil survey of Ocala National Forest area, Florida. U.S. Govt. Print. Office, Washington, D.C. Bartoli, F., and L. P. Wilding. 19 80. Dissolution of biogenic opal as a function of its physical and chemical properties. Soil Sci Soc Am. J. 44: 873-878. Bartram, W. (1791) 1955. The travels of William Bartram. M. Van Doren (ed.) Dover Publications, Inc., New York, N.Y. Baxter, F. P., and F. D. Hole. 1967. Ant (Formica cinerea ) pedoturbation in a prairie soil. Soil Sci. Soc. Am. Proc. 31: 425-428. Bremner, J. M., and D. S. Jenkinson. 1960. Determination of organic carbon in soil. II. Effect of carbonized materials. J. Soil Sci. 11: 401-408. Britt, R. W. 1973. Management of natural stands of Choctawha tehee sand pine. p. 135-143. In USDA Forest Service, Sand pine symposium proceedings. Southeast. For Expt. Sta., USDA For. Serv. Gen. Tech. Rep. SE-2. Brooks, H. K. 19 72. The geology of the Ocala National Forest. p. 81-9 2. In S C. Snedaker and E. A. Lugo (eds.) Ecology of the Ocala National Forest. USDA For. Serv., South. Region, Atlanta, Ga 120

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121 Buntley, G. J., and R. I. Papendick. 1960. Worm-worked soils of eastern South Dakota, their morphology and classification. Soil Sci. Soc. Am. Proc. 24: 128-132. Carlisle, V. W., R. E. Caldwell, F. Sodek, L. C. Hammond, F. G. Calhoun, M. A. Granger, and H. L. Breland. 1978. Characterization data for selected Florida soils. Soil Sci. Res. Rep. No. 78-1, Univ. Fla., Gainesville, Fla. Chapman, H. H. 1932. Is the longleaf type a climax? Ecol. 13: 328-334. Christensen, N. L. 1981. Fire regimes in southeastern ecosystems, p. 112-136. In_ H. A. Mooney, T. M. Bonnicksen, N. L. Christensen, J. E. Lotan, and W. A. Reiners (eds.) Fire regimes and ecosystem properties. USDA For. Serv. Gen. Tech. Rep. WO-26 Cooper, R. W. 1973. Fire and sand pine. p. 207-212. In USDA Forest Service, Sand pine symposium proceedings. Southeast. For. Expt. Sta., USDA For. Serv. Gen. Tech. Rep. SE-2. Day, G. M. 1953. The Indian as an ecological factor in the northeastern forest. Ecol. 34: 329-346. Dyal, R. S., Jr., and M. Drosdoff. 1941. Determining organic matter in Florida soils. Proc. Soil Sci. Soc. Fla. 3: 91-96. Edwards, C. A., and J. R. Lofty. 1977. Biology of earthworms. 2nd ed. Chapman and Hall, London. Gentry, J. B., and K. L. Stiritz. 1972. The role of the Florida Harvester Ant, Pogonomyrmex badius, in old field mineral nutrient relationships. Environ. Ent. 1: 39-41. Hallsworth, E. G., and H. D. Waring. 1964. Studies in pedogenesis in New South Wales. VIII. An alternative hypothesis for the formation of the solodizedsolonetz of the Pilliga District. J. Soil Sci. 15: 158-177. Hansen, K. L. 196 3. The burrow of the gopher tortoise. Fla. Acad. Sci. Quart. J. 26: 353-360.

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122 Harlow, R. F., and P. Bielling. 1961. Controlled burning studies in the longleaf pine-turkey oak assoication on the Ocala National Forest. Proc. Ann. Conf. Southeast. Assoc. Game Fish Conrni. 15: 9-24. Harlow, R. F., B. A. Sanders, J. B. Whelan, and L. C. Chappel. 19 80. Deer habitat on the Ocala National Forest: improvement through forest management. S. J. Appl. For. 4: 98-102. Harper, R. M. 1914a. Geography and vegetation of northern Florida. Fla. Geol. Surv., 6th Ann. Rep.: 163-391. Harper, R. M. 1914b. The coniferous forests of eastern North America. Pop. Sci Mon. 85: 338-361. Harper, R. M. 1915. The natural resources of an area in central Florida. Fla. Geol. Surv., 7th Ann. Rep.: 117-188. Harper, R. M. 1921. Geography of central Florida. Fla. Geol. Surv., 13th Ann. Rep.: 71-307. Heizer, R. F. 1956. Primitive man as an ecologic factor. Kroeber Ant. Soc. Pap. 13: 1-31. Hillel, D., and H. Talpaz. 1977. Simulation of soil water dynamics in layered soils. Soil Sci. 123: 54-62. Hole, F. D. 1981. Effects of animals on soil. Geoderma 25: 75-112. Hough, W. A. 1973. Fuel and weather influence wildfires in sand pine forests. USDA For. Serv. Res. Pap. SE-106. Howden, H. F. 19 52. A new name for Geotrupes ( Pelto trupes ) chalybeus Le Conte, with a description of the larva and its biology. Coleopterists Bull. 6: 41-48. IFAS 19 81. Nutrient level ratings. Highlights in Soil Sci., No. 7, p. 3. Inst. Food Agric. Sci., Univ. Fla., Gainesville, Fla. Jackson, M. L. 1958. Soil chemical analysis. PrenticeHall, Inc., Englewood Cliffs, N.J.

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123 Jones, R. L., and A. H. Beavers. 1964. Aspects of catenary depth distribution of opal phytoliths in Illinois soils. Soil Sci. Soc. Am. Proc. 28: 413-416. Klein, R. L., and J. W. Geis. 1978. Biogenic silica in the pinaceae. Soil Sci. 126: 145-156. Kowal, N. E. 1966. Shifting cultivation, fire, and pine forest in the Cordillera Central, Luzon, Philippines. Ecol. Monogr 36: 389-419. Kurz, H. 1942. Florida dunes and scrub, vegetation and geology. Fla. Geol. Surv., Geol Bull. 23: 1-154. Laessle, A. M. 1958. The origin and successional relationships of sandhill vegetation and sand-pine scrub. Ecol. Monogr. 28: 361-387. Laessle, A. M. 1968. Relationships of sand pine scrub to former shore lines. Fla. Acad, Sci. Quart. J. 30: 269-286. Lyford, W. H. 1963. Importance of ants to brown podzolic soil genesis in New England. Harvard For. Pap. No. 7, Harvard Univ., Petersham, Mass. McKee, W. H., Jr., 1982. Changes in soil fertility following prescribed burning on coastal plain sites. USDA For. Serv. Res. Pap, SE-234. Milanich, J. T., and C. H. Fairbanks. 1980. Florida archeology. Academic Press, New York, N.Y. Miles, S. R., and P. C. Singleton. 1975. Vegetative history of Cinnabar Park in Medicine Bow National Forest, Wyoming. Soil Sci. Soc, Am. Proc. 39: 1204-1208. Mitchell, C. C, and R. D. Rhue 1979. Procedures used by the University of Florida soil testing and analytical research laboratories. Soil Sci. Res. Rep. No. 79-1, Univ. Fla., Gainesville, Fla. Mohlenbrock, R. H. 19 76. Woody plants of the Ocala National Forest, Florida. Castanea 41: 309-319. Mulvania, M. 19 31. Ecological survey of a Florida scrub. Ecol. 12: 528-540.

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124 Nash, G. V. 1895. Notes on some Florida plants. Bull. Torrey Bot. Club 22: 141-161. Oliver, C. D. 19 78. Subsurface geologic formations and site variations in upper sand hills of South Carolina. J. For. 76: 352-354. Patrick, R. 1977. Ecology of freshwater diatoms. p. 283-332. In D. Werner (ed.) The biology of diatoms. Univ. Calif. Press, Berkeley, Calif. Prickle, E. C, W. H. Yoho, A. T. Allen, and A. C. Edgar. 1963. Citronelle sediments of peninsular Florida. Fla. Acad. Sci. Quart. J. 26: 105-149. Rhue, R. D., and J. B. Sartain. 1978. A survey of the fertility status of Florida soils as indicated by selected soil test results. Soil Crop Sci. Soc. Fla. Proc. 38: 112-116. Rovner, I. 1971. Potential of opal phytoliths for use in paleoecological reconstruction. Quat. Res. 1: 343-359 Sauer, C, 0. 1950. Grassland climax, fire, and man. J. Range Mgmt. 3: 16-21. Sellards, E. H. 1912. Soils and other surface residual materials of Florida. Fla. Geol. Surv., 4th Ann. Rep.: 7-79. Smith, F. B. 1944. The occurrence and distribution of algae in soils. Fla. Acad. Sci. Proc. 7: 44-49. Stewart, 0. C. 1953. Why the Great Plains are treeless. Colo. Quart. 2: 40-50. Taylor, H. M., G. M. Roberson, and J. J. Parker, Jr. 1966. Soil strength-root penetration relations for mediumto coarse-textured soil materials. Soil Sci. 102: 18-22. Thorp, J. 1949. Effects of certain animals that live in soils. Sci. Mon. 68: 180-191. Twiss, P. C, E. Suess, and R. M. Smith. 1969. Morphological classification of grass phytoliths. Soil Sci. Soc. Am. Proc. 33: 109-115. USDA. 1929. Volume, yield, and stand tables for second-growth southern pines. USDA Misc. Pub. 50. Van Pelt, A. F., Jr. 1956. The ecology of the ants of the Welaka Reserve, Florida (Hymenoptera : Formicidae) Am. Midi. Nat. 56: 358-387.

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125 Veno, P. A. 1976. Successional relationships of five Florida plant communities. Ecol. 57: 49 8-50 8. Vignoles, C. 1823. Observations upon the Floridas. Bliss, New York, N.Y. Wahlenberg, W. G. 1946. Longleaf pine, its use, ecology, regeneration, protection, growth and management. Charles Latrop Pack For. Found., Washington, D.C. Watts, W. A. 1969. A pollen diagram from Mud Lake, Marion County, north-central Florida. Geol. Soc. Am. Bull. 80: 631-642. Webber, H. J. 1935. The Florida scrub, a fire-fighting association. Am, J. Bot. 22: 344-361. Whitney, M. 1898. The soils of Florida. USDA Bull. 13: 14-27. Wilding, L. P. 1967. Radiocarbon dating of biogenic opal. Sci. 156: 66-67. Wilding, L. P., and L. R. Drees. 1968a. Biogenic opal in soils as an index of vegetative history in the Prairie Peninsula, pp. 99-103. In R. E. Bergstrom (ed.) The Quaternary of Illinois. Univ. 111. Coll. Agric. Spec. Pub. 14. Wilding, L. P., and L. R. Drees. 1968b. Distribution and implications of sponge spicules in surficial deposits in Ohio. Ohio J. Sci. 68: 92-99. Wilding, L. P., N. E. Smeck, and L. R. Drees. 19 77. Silica in soils: quartz, cristo alite, tridymite, and opal. p. 471-552. In J. B. Dixon and S. B Weed (eds.) Minerals in soil environments. Soil Sci. Soc. Am., Madison, Wise. Witty, J. E., and E. G. Knox. 1964. Grass opal in some chestnut and forested soils in north-central Oregon. Soil Sci, Soc. Am. Proc. 28: 685-688. Woodruff, R. E, 1973. The scarab beetles of Florida. Fla. Dept. of Agric. Consumer Services, Gainesville, Fla. Young, F. N. 1950. Notes on the habits and habitat of Geotrupes chalybeus Le Conte in Florida. Psyche 57: 88-92.

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126 Young, F. N., T. H. Hubbell, and D. W. Hayne. 1955. Further notes on the habits of Geotrupes (Coleoptera Geotrupidae) Psyche 62: 53-54.

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BIOGRAPHICAL SKETCH Paul John Kalisz was born in Pennsylvania. After two years at the University of Notre Dame, he postponed his education to serve in the Peace Corps (Nepal) and then in the Navy. He received a B.S. in forest science from The Pennsylvania State University, and an M.S. in agronomy (soil science) from Cornell University. He is married to Barbara Fischer, and has one daughter. 127

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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. Earl L. Stone, Chairman Professor of Soil Science 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. William L. Pritchett Professor of Soil Science 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. Gholz ^ it Professor ^f F-<5rest 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 Doctor of Philosophy. y Associate Professor of Soil Science

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This dissertation was submitted to the Graduate Faculty of the College of Agriculture and to the Graduate Council, and was accepted as partial fulfillment of the requirements for the degree of Doctor of Philosophy. December 1982 -Dean, Coldlege of Agriculture Dean for Graduate Studies and Research