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Methods to restore native plant communities after invasive species removal

Permanent Link: http://ufdc.ufl.edu/UFE0041336/00001

Material Information

Title: Methods to restore native plant communities after invasive species removal marl prairie ponds and an abandoned phosphate mine in Florida
Physical Description: 1 online resource (113 p.)
Language: english
Creator: Villazon, Kathryn
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2009

Subjects

Subjects / Keywords: cogongrass, density, elevation, flatwoods, invasive, pine, planting, propagule, restoration, revegetation, size, species, wetlands
Environmental Horticulture -- Dissertations, Academic -- UF
Genre: Horticultural Science thesis, M.S.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: Because Florida's natural ecosystems are increasingly invaded by exotic and undesirable plant species, invasive species removal is a major part of ecosystem restoration, and revegetation efforts after invasive species clearing is often necessary. Invasive species removal can be achieved through mechanical, cultural, chemical, or biological means. Few studies have addressed methods for successful native plant recolonization after invasive species removal using revegetation strategies. Different techniques for native species establishment were investigated in formerly invaded hydric and mesic-xeric ecosystems. The hydric site, consisting of two marl prairie ponds, and a mesic-xeric site, an abandoned phosphate mine, were both initially monotypic stands of Salix caroliniana Michx. (coastalplain willow) and Imperata cylindrica (L.) P. Beauv. (cogongrass), respectively. Following removal of the invasive species either by mechanical or chemical methods, different revegetation techniques were investigated. At the hydric site, the effects of two planting densities, two elevations, and two different propagule sizes on plant survival and volume of installed native plants were researched. Results conclude that planting at sparse densities (3 ft centers) is most desirable since it is cost-effective and survival rates were higher, although dense plantings initially increased biodiversity and species richness. Effect of planting elevation on survival and volume was species-specific. Using 5-inch potted plants is recommended to maximize survival and reduce the necessity for subsequent plantings. At the mesic-xeric site, two planting regimes (grasses or grasses/forbs/shrub) and two herbicide applications for removal of I. cylindrica were studied to assess the effects of these factors on plant volume and survival of planted native species. Generally, using grasses/forbs/shrub plantings increases species richness, initial establishment and survival. Herbicide application to encroaching I. cylindrica decreased cover of the invasive species, but did not increase native plant volume in low structural diversity plots, and actually decreased native volume in high structural diversity plots. Results show that revegetating after invasive species removal initially increases biodiversity and species richness. Installing plants at sparse densities is both cost effective and promotes planted species growth, and using larger propagules maximizes survival. Planting native species alone deterred I. cylindrica spread, and application of herbicide after revegetating was not beneficial.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility: by Kathryn Villazon.
Thesis: Thesis (M.S.)--University of Florida, 2009.
Local: Adviser: Reinhardt Adams, Carrie H.
Electronic Access: RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2011-12-31

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2009
System ID: UFE0041336:00001

Permanent Link: http://ufdc.ufl.edu/UFE0041336/00001

Material Information

Title: Methods to restore native plant communities after invasive species removal marl prairie ponds and an abandoned phosphate mine in Florida
Physical Description: 1 online resource (113 p.)
Language: english
Creator: Villazon, Kathryn
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2009

Subjects

Subjects / Keywords: cogongrass, density, elevation, flatwoods, invasive, pine, planting, propagule, restoration, revegetation, size, species, wetlands
Environmental Horticulture -- Dissertations, Academic -- UF
Genre: Horticultural Science thesis, M.S.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: Because Florida's natural ecosystems are increasingly invaded by exotic and undesirable plant species, invasive species removal is a major part of ecosystem restoration, and revegetation efforts after invasive species clearing is often necessary. Invasive species removal can be achieved through mechanical, cultural, chemical, or biological means. Few studies have addressed methods for successful native plant recolonization after invasive species removal using revegetation strategies. Different techniques for native species establishment were investigated in formerly invaded hydric and mesic-xeric ecosystems. The hydric site, consisting of two marl prairie ponds, and a mesic-xeric site, an abandoned phosphate mine, were both initially monotypic stands of Salix caroliniana Michx. (coastalplain willow) and Imperata cylindrica (L.) P. Beauv. (cogongrass), respectively. Following removal of the invasive species either by mechanical or chemical methods, different revegetation techniques were investigated. At the hydric site, the effects of two planting densities, two elevations, and two different propagule sizes on plant survival and volume of installed native plants were researched. Results conclude that planting at sparse densities (3 ft centers) is most desirable since it is cost-effective and survival rates were higher, although dense plantings initially increased biodiversity and species richness. Effect of planting elevation on survival and volume was species-specific. Using 5-inch potted plants is recommended to maximize survival and reduce the necessity for subsequent plantings. At the mesic-xeric site, two planting regimes (grasses or grasses/forbs/shrub) and two herbicide applications for removal of I. cylindrica were studied to assess the effects of these factors on plant volume and survival of planted native species. Generally, using grasses/forbs/shrub plantings increases species richness, initial establishment and survival. Herbicide application to encroaching I. cylindrica decreased cover of the invasive species, but did not increase native plant volume in low structural diversity plots, and actually decreased native volume in high structural diversity plots. Results show that revegetating after invasive species removal initially increases biodiversity and species richness. Installing plants at sparse densities is both cost effective and promotes planted species growth, and using larger propagules maximizes survival. Planting native species alone deterred I. cylindrica spread, and application of herbicide after revegetating was not beneficial.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility: by Kathryn Villazon.
Thesis: Thesis (M.S.)--University of Florida, 2009.
Local: Adviser: Reinhardt Adams, Carrie H.
Electronic Access: RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2011-12-31

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2009
System ID: UFE0041336:00001


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METHODS TO RESTORE NATIVE PL ANT COMMUNITIES AFTER INVASIVE SPECIES REMOVAL: MARL PR AIRIE PONDS AND AN ABANDONED PHOSPHATE MINE IN FLORIDA By KATHRYN AUBREY VILLAZON A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORID A IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2009 1

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2009 Kathryn Aubrey Villazon 2

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To my sister, Daniela Dutra, science will never be the same again 3

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ACKNOWLEDGMENTS I thank my parents, Silvio and Mary Villazo n, for all their support, confidence, and continual belief in my botanic prowess. I th ank my brother, Gerald Villazon, for his sidesplittingly crass sense of humor and helping me realize life is not always supposed to be serious. I thank my committ ee members, Carrie Im alwa ys smilingno matter what! Reinhardt Adams, Gregory IS THAT A WI LD EMU?! MacDonald, and Michael You should be used to it, youre from Lake City, remember? Kane for their constant input and overwhelming amendments to my thesis research. I thank my best friends, especially Daniela Du tra, Richard Phelan, and Jana Harrison, for helping me keep my head on straight and not allowing me to resort to precarious methods of stress relief, like buzzard bowling. I thank my better half, Aaron Collins, and his family for intelligent conversation, humorous spirit s, support, and delectable food. I thank the funding agencies fo r providing financial support: United States Fish and Wildlife Service, University of Florida Environmental Horticulture Department, and Florida Fish and Wildlife Conservation Commission. I thank Nancy Bissett of The Natives, Inc. for all her help in plant sele ction and proving that soft-spoken people are seldom unheard. I thank Larry Richardson (Florida Panther National Wildlife Refuge) for never allowing a boring day to pass in t he swamp while collecting data or removing weeds. I thank Tim King (Tenoroc Fish Managem ent Area) for the hours of entertaining hunting stories (and football tickets ). I thank Bill Where is my moon pie, Ms. Villazon?! Haller for his consultation on herbicide selection and application rates for invasive species removal, as well as his entertaining hunting experiences (Is that really how it happened, Dr. Haller?). I also thank all t hose who assisted in data collection (and preventing me from cardiac arrest) throughout the years: Nancy Steigerwalt, Nancy 4

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Philman, Anne Frances, Emily Austen, Dallas Scott, Julie Sorenson, Ryan Graunke, Leah Cobb, Cabrina Hamilton, Jonathan Schwartz Mary Villazon, Aaron, J.J. Sadler, and the weed shop folks (Brandon Fast, Court ney Stokes, Bucky Dobrow). Finally, I thank my little beagle puppy, Spanky, for cons tant entertainment through his innocent, yet relentless, antics (as well as the brain hemorrhage he so charitably bestowed upon me after chewing through 3 of my external hard drives and my laptop power cord). 5

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TABLE OF CONTENTS page ACKNOWLEDGMENTS ..................................................................................................4 LIST OF TABLES ............................................................................................................8 LIST OF FIGURES ........................................................................................................10 ABSTRACT ...................................................................................................................13 CHAPTER 1 INTRODUCTION AND LI TERATURE REVIEW.....................................................15 Introduction .............................................................................................................15 Invasive Species Effects on Ecosystems .........................................................15 Removal of Invasive Species ...........................................................................17 Revegetating after Removal .............................................................................18 Model Systems .......................................................................................................21 Freshwater Depression Marshes within Everglades Marl Prairies ....................21 Pine Flatwoods .................................................................................................22 Research Goals ......................................................................................................24 2 REVEGETATING MARL PRAIRI E PONDS AFTER INVASIVE SPECIES REMOVAL ..............................................................................................................25 Introduction .............................................................................................................25 Materials and Methods ............................................................................................27 Study Site .........................................................................................................27 Site Preparation ................................................................................................27 Plant Material Acquisition and Propagation ......................................................28 Experimental Design ........................................................................................29 Experiment 1: Effects of density and elevation on plant establishment ......29 Experiment 2: Effe cts of propagule size and elevation on plant establishment ..........................................................................................29 Data Collection .................................................................................................30 Statistical Analyses ..........................................................................................30 Results ....................................................................................................................31 Experiment 1 Effects of Planting Elevation and Planting Density on Percent Survival and Plant Volume ...............................................................31 Effects of elevation .....................................................................................32 Effect of planting density ............................................................................32 Effects of elevation and plant ing density on species richness ....................33 Experiment 2 Effects of Planting Elevation and Plant Size on Percent Survival and Volume .....................................................................................34 Effects of elevation .....................................................................................34 6

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Effects of propagule size ............................................................................34 Effects of elevation and pr opagule size on species richness .....................35 Discussion ..............................................................................................................35 Hydrology and Elevation Drive Establishment ..................................................36 The Role of Planting Density and Propagule Size ............................................38 Comparing Planting to Natural Recolonization .................................................40 Restoration Trajectories ...................................................................................41 Conclusions: Implications for Practice ....................................................................42 3 RESTORATION OF PINE FLATWOOD S IN FLORIDA UPON REMOVAL OF COGONGRASS ( IMPERATA CYLINDRICA ).........................................................72 Introduction .............................................................................................................72 Imperata cylindrica : Biology and Morphology ...................................................72 Invasive Species and Revegetation .................................................................74 Materials and Methods ............................................................................................76 Study Site .........................................................................................................76 Experimental Design ........................................................................................77 Data Collection .................................................................................................78 Statistical Analysis ............................................................................................78 Results ....................................................................................................................79 Plant Survival and Volume Over Time ..............................................................80 Effects of Herbicide Application on I. cylindrica and Planted Species ..............81 Effects of Structural Diversity on Species Richness and Percent Cover of I. cylindrica .......................................................................................................82 Discussion ..............................................................................................................82 Structural Diversity Influenc ed Planted Species Establishment ........................83 Follow-up Herbicide Pr ovided Mixed Results ...................................................84 Post-planting Community Dynamics .................................................................84 Relative Costs of Treatments ...........................................................................85 Conclusions: Implications for Practice ....................................................................85 4 CONCLUSION S...................................................................................................102 LIST OF REFERENCES .............................................................................................105 BIOGRAPHICAL SKETCH ..........................................................................................113 7

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LIST OF TABLES Table page 2-1 Species used for revegetation in both experiments. ...........................................44 2-2 Soil analysis for both ponds after r egrading, at time of planting, and 18 months after planting. .........................................................................................45 2-3 Analysis of variance for effects of planting density, elev ation, months after initial planting, and pond lo cation on plant volume and for each of the eight species planted. ..................................................................................................46 2-4 Analysis of variance for effects of planting density, elev ation, months after initial planting, and pond lo cation on percent survival overall and for each of the eight species planted. ...................................................................................47 2-5 Analysis of variance for effects of planting density and planting elevation on species richness. ................................................................................................48 2-6 Analysis of variance for effects of propagule size, elevation, and months after initial planting, on overa ll plant volume and for each of the five species planted. ...............................................................................................................49 2-7 Analysis of variance for effects of propagule size, elevation, and months after initial planting on overall percent survival and for each of the five species planted. ...............................................................................................................50 2-8 Analysis of variance for effects of planting elevati on and propagule size on species richness. ................................................................................................51 2-9 Species-specific plant volu me response to planting treatments. ........................52 2-10 Species-specific percent surv ival response to planting treatments. ....................53 2-11 Percent cover and species composition of naturally recolonizing species and their frequency of occurrence 12 months af ter planting for effects of planting density and planting elevation on species response. ..........................................54 2-12 Percent cover and species composition of naturally recolonizing species and their frequency of occurrence 12 months af ter planting for effects of planting elevation and propagule size on plant response.................................................55 3-1 List of species, quantity, total num ber of plants, cost per plant, and overall cost for species used for revegetation. ...............................................................87 8

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3-2 Analysis of variance for the effe cts of planting regime (Reg.), herbicide application (Herb.), and 0, 6, 9, 12, and 18 months after initial planting (MAP) on percent survival of all surviving species. ........................................................88 3-3 Analysis of variance for the effe cts of planting regime (Reg.), herbicide application (Herb.), and 0, 6, 9, 12, and 18 months after initial planting (MAP) on total plant volume and species richness of all surviving species. ..................89 A-1 Number of plants per species pres ent in seedbank at TFMA 0, 3, 6, and 9 months after planting in the I. cylindrica patch, edge of pl anting area, and inside the planting area. ...................................................................................104 9

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LIST OF FIGURES Figure page 2-1 Depth to water table was measured using a laser level at time of planting and installed wells thereafter at either planting elevation. Prec ipitation data also shown over data collection period (for elevation data, mean of water table height at 3 wells and standard error are shown). ................................................56 2-2 Cyperus haspan the effects of planting elevation and planting density on plant volume and percent survival. Mean of 10 replicat ions followed by standard error; n=30 for sparse planting, n=60 for dense planting. ....................57 2-3 Eleocharis atropurpurea the effects of planting elevation and planting density on plant volume and percent su rvival. Mean of 10 replications followed by standard error; n=30 for spar se planting, n=60 for dense planting. .58 2-4 Fuirena breviseta the effects of planting elevation and planting density on plant volume and percent survival. Mean of 10 replications followed by standard error; n=30 for sparse planting, n=60 for dense planting. ....................59 2-5 Juncus polycephalos the effects of planting elevation and planting density on plant volume and percent survival. Mean of 10 replications followed by standard error; n=30 for sparse planting, n=60 for dense planting. ....................60 2-6 Pluchea rosea the effects of planting elevation and planting density on plant volume and percent survival. Mean of 10 replicat ions followed by standard error; n=30 for sparse planting, n=60 for dense planting. ....................61 2-7 Proserpinaca palustris the effects of planting elevation and planting density on plant volume and percent survival. Mean of 10 replications followed by standard error; n=30 for sparse planting, n=60 for dense planting. ....................62 2-8 Rhynchospora colorata the effects of planting elevation and planting density on plant volume and percent su rvival. Mean of 10 replications followed by standard error; n=30 for spar se planting, n=60 for dense planting. .63 2-9 Verbena hastata the effects of planting el evation and planting density on plant volume and percent survival. Mean of 10 replicat ions followed by standard error; n=30 for sparse planting, n=60 for dense planting. ....................64 2-10 Effects of planting density on spec ies richness at either study pond for Experiment 1. Mean of 10 replications followed by standard error. ...................65 2-11 Bacopa caroliniana the effects of planting el evation and propagule size on plant volume and percent survival. .....................................................................66 10

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2-12 Lythrum alatum the effects of planting elevation and propagule size on plant volume and percent survival. Mean of 3 replications followed by standard error, n=5. ............................................................................................67 2-13 Pluchea rosea the effects of planting elev ation and propagule size on plant volume and percent survival. Mean of 3 replications followed by standard error, n=5. ...........................................................................................................68 2-14 Proserpinaca palustris the effects of planting elevation and propagule size on plant volume and percent survival. Mean of 3 replications followed by standard error, n=5. ............................................................................................69 2-15 Verbena hastata the effects of planting el evation and propagule size on plant volume and percent survival. Mean of 3 replications followed by standard error, n=5. ............................................................................................70 2-16 Effects of propagule size on species ri chness for Experiment 2. Mean of 3 replications followed by standard error. ..............................................................71 3-1 Schematic of a circular study plot with 12 ft diameter planting area and 2 ft buffer reserved for the follow up herbic ide application. Half of all experimental units were a ssigned an herbicide treatment. .................................90 3-2 Precipitation patterns during the study period (Marc h 2008 (initial time of planting and 12 months after planti ng)-September 2009 (6 months after planting and 18 months after planting)) and ten year average. ..........................91 3-3 Andropogon brachystachyus the effects of planting regime and herbicide application on plant volume and survival. Mean of 6 replications followed by standard error. ....................................................................................................92 3-4 Andropogon glomeratus the effects of planting regime and herbicide application on plant volume and survival. Mean of 6 replications followed by standard error. ....................................................................................................93 3-5 Aristida stricta the effects of planting regime and herbicide application on plant volume and survival. Mean of 6 replications followed by standard error. ..94 3-6 Dyschoriste oblongifolia the effects of herbicide on plant volume and survival. Mean of 6 replicat ions followed by standard error. ..............................95 3-7 Eragrostis spectabilis the effects of planting regime and herbicide application on plant volume and survival. Mean of 6 replications followed by standard error. ....................................................................................................96 3-8 Liatris spicata the effects of herbicide application on plant volume and survival. Mean of 6 replicat ions followed by standard error. ..............................97 11

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3-9 Muhlenbergia capillaris the effects of planting regime and herbicide application on plant volume and survival. Mean of 6 replications followed by standard error. ....................................................................................................98 3-10 Panicum anceps the effects of planting regi me and herbicide application on plant volume and survival. Mean of 6 replications followed by standard error. ..99 3-11 Pityopsis graminifolia the effects of herbicide application on plant volume and survival. Mean of 6 replicat ions followed by standard error. .....................100 3-12 Effects of planting regime and herbi cide application on species richness and percent cover of I. cylindrica Mean of 6 replications followed by standard error. .................................................................................................................101 12

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Abstract of Thesis Pres ented to the Graduate School of the University of Florida in Partial Fulf illment of the Requirements for t he Degree of Master of Science METHODS TO RESTORE NATIVE PL ANT COMMUNITIES AFTER INVASIVE SPECIES REMOVAL: MARL PR AIRIE PONDS AND AN ABANDONED PHOSPHATE MINE IN FLORIDA By Kathryn Aubrey Villazon December 2009 Chair: Carrie Reinhardt Adams Major: Horticultural Science Because Floridas natural ecosystems ar e increasingly invaded by exotic and undesirable plant species, invasive specie s removal is a major part of ecosystem restoration, and revegetation efforts after inva sive species clearing is often necessary. Invasive species removal can be achieved through mechanical, cultural, chemical, or biological means. Few studies have address ed methods for successful native plant recolonization after invasive species removal using revegetation strategies. Different techniques for native specie s establishment were investigated in formerly invaded hydric and mesic-xeric ecosystem s. The hydric site, consisting of two marl prairie ponds, and a mesic-xeric site, an abandoned phosphate mine, were both initially monotypic stands of Salix caroliniana Michx. (coastalplain willow) and Imperata cylindrica (L.) P. Beauv. (cogongrass), respectively. Following removal of the invasive species either by mechanical or chemic al methods, we investigated different revegetation techniques. At the hydric site, the effects of two planting densit ies, two elevations, and two different propagule sizes on plant survival and volume of installed native plants were 13

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researched. Results conclude that planting at sparse densities (3 ft centers) is most desirable since it is cost-effective and su rvival rates were higher, although dense plantings initially increased biodiversity and species rich ness. Effect of planting elevation on survival and volume was speciesspecific. Using 5-inch potted plants is recommended to maximize survival and reduce the necessity for subsequent plantings. At the mesic-xeric site, two planting r egimes (grasses or grasses/forbs/shrub) and two herbicide applications for removal of I. cylindrica were studied to assess the effects of these factors on plant volume and survival of planted native species. Generally, using grasses/forbs/shrub plantin gs increases species richness, initial establishment and survival. Herbicide application to encroaching I. cylindrica decreased cover of the invasive species, but did not in crease native plant volume in low structural diversity plots, and actually decreased native vo lume in high structural diversity plots. Results show that revegetating after inva sive species removal initially increases biodiversity and species richness. Installi ng plants at sparse densities is both cost effective and promotes planted species grow th, and using larger propagules maximizes survival. Planting native species alone deterred I. cylindrica spread, and application of herbicide after revegetating was not beneficial. 14

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CHAPTER 1 INTRODUCTION AND LI TERATURE REVIEW Introduction Floridas landscape consists of unique and highly valued natural conservation areas including: forests, flatwoods, prairi es, swamps, marshes and waterways. Rapid population growth and natural pr ocesses make Florida susceptible to land disturbances. Disturbed land results naturally from hurric anes (Lugo 2000) and severe fire as well as from anthropogenic causes such as mini ng (Carrick & Kruger 2007) urbanization, and construction. Similarly, upon large-scale re moval of invasive species, ecosystems may become disturbed and barren, susceptible to further reinvasion (Harper et al. 1961; Johnstone 1986), and may not adequately be recol onized with desirable native species. In efforts to restore degraded ecosystems on Floridas public land, over 33 million dollars were spent in 2007 controlling 122,0 00 hectares of both aquatic and terrestrial invasive species (DEP 2009). If revegetatio n strategies are not implemented, primary removal of invasive species can lead to t he introduction of other undesirable species, potentially resulting in a secondary m onotypic population (Ogden & Remanek 2005; Shilling et al. 1997). Methods for native s pecies restoration after invasive species removal are needed, but little resear ch has addressed this issue. Invasive Species Effects on Ecosystems When invasion of an undesirable species occurs in a healthy ecosystem, several scenarios are possible: (1) the ecosystem re mains unchanged, (2) a fter invasion, minor alterations to habitat or biodiversity occu r, or (3) the invasive species becomes dominant in the ecosystem. Invasion can lead to extreme habita t degradation, loss of ecosystem function, and a decrease in biod iversity (Williams 2007). Of these three 15

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scenarios, this research will address the thir d situation where invasive species removal is a critical component of restoration efforts. Invasive species have negative ecosyst em impacts in both hydric and mesicxeric ecosystems. Where invasive specie s impacts to hydrology lead to extensive changes in native species distribution, removal is critical for ecosystem recovery. For instance, in Everglades National Park, Melaleuca quinquenervia (Cav.) S.F. Blake (punktree) alters hydrology through interception in rainfall (where precipitation is intercepted by the canopy and evaporat ed back into the atmosphere), raises evapotranspiration rates higher than native species (such as Cladium mariscus (L.) Pohl ssp. jamaicense (Crantz) Kk. (Jamaican swamp sawgrass) ), and also reduces surface flow (Laroche 1998). Other aquatic invasive species, such as Hydrilla verticillata (L. f.) Royle (hydrilla) Pistia stratiotes (L.) (water lettuce) and Eichhornia crassipes (Mart.) Solms (water hyacinth) elevate evapotranspiration rates. Invasion of floating aquatic species also results in drastic loss of desired submerged v egetation because of interruption of sunlight (Deuver et al. 1986). Invasive species in more mesic sites affect the ecosystem in a variety of ways; for instance Cyperus spp. displaces native species through rapid reproduction and Imperata cylindrica (cogongrass) alters fire regimes and plant community composition. An invasive fern species, Lygodium microphyllum (Cav.) R. Br. (small-leaf climbing fern) acts as a fire ladder and upon fire entry, decimates populations of native trees (Pemberton & Ferriter 1998). These negative impacts to ecosystems caused by invasion motivate natural resource managers to develop strategies to reinstate self-sustaining diverse ecosystems by accelerating ecosystem recovery. Removal of invasive species 16

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represents elimination of a barrier to ecosystem reco very, and is a major component of most restoration projects. Removal of Invasive Species Methods for removing invasive species in clude mechanical, chemical, biological, and cultural methods of contro l. An example of mechanic al control is harvesting for E. crassipes or excavation of S. caroliniana The alligatorweed flea beetle is used for biocontrol of Alternanthera philoxeroides (Mart.) Griseb. (alligatorweed), just as Ctenopharyngodon idella (grass carp) is used on H. verticillata Cultural control, such as crop rotation, can be effective in removing undesirable weedy species from agronomic crops. However, the use of chem ical herbicides is the most widely-used means of controlling invasive species (Valenti 2002). Repeated chemical herbicide applications to treat invasive species can alter soil properties (Pickart et al. 1998) and microbial communities (Buisson et al. 2006), as well as decrease plant cover. Similarly, mec hanical control, such as scraping, removes plant communities and leaves modified so il conditions. These disturbances alter ecosystems on both spatial and temporal scale s (White 1985). In some instances, moderate soil disturbanc e creates favorable conditions fo r the establishment of a new suite of species (Platt 1975; McIntyre et al. 1995). In contrast, other studies suggest severe soil disturbance provides little shel ter for seedlings thereby creating a less tolerable environment for seedling growth and development (Rapp & Rabinowitz 1985). Regardless, recolonization of a high quality plant community on disturbed soil will take years for degraded ecosystems, and may never occur unassisted for others. 17

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Revegetating after Removal Several factors affect plant community recovery after large scale invasive species removal: (1) distance from off-site propagule sources of t he original invasive species, (2) factors affecting the natural dispersal of weed seeds, (3) recolonization from on-site propagule sources (seed bank and surv iving individuals, and (4) reinvasion by secondary undesirable species on bare ground. Because the transition from invasive species control to native plant re colonization is uncertain, and planting after disturbance can prevent or slow invasion (S pieles 2005), revegetat ion is an important, logical subsequent step upon removal of invasive species (Gutrich et al. 2009). Little is known about maximizing the pot ential of revegetation success in a restoration context. Selecting appropriate plant material, eval uating water source-plant location, postplanting invasive species control, and monito ring newly establishing native species can increase the chances for revegetation success. Revegetation can be accomplished through seeding or installing plants. Seeding is more common and appropriate when monetary resources are limited (Walker et al. 2004), land is easily sowable (Kiehl et al. 2006; Lindborg 2006), and seeds are not persistent in the seedbank (M ilberg 1995; Bakker et al. 2002) If seeding fails to establish a native species, installing plug-plants which have been grown in a greenhouse may be another option since plugplants have greater establishment success than seed (Wallin et al. 2009), though little species-specific information is available to maximize the es tablishment with this method. Understanding factors that affect revegetation of disturbed sites could potentially maximize the impact of these efforts. Ut ilizing different plant propagule sizes (smaller plugs versus container plants), determining t he correct planting location (shade versus 18

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sun, wet versus dry, acidic versus alka line soil), and planting at an appropriate planting density (dense or sparse) can collectivel y influence the success of restoration. Planting density is import ant in both promoting the growth and spread of native species and reducing reinvasion Kim et al. (2006) planted Salix spp. stakes of 90 cm tall x 1.3-2.5 cm in diameter at densities of 0.60 m and 0. 91 m on center and concluded these are most effective for control of Phalaris arundinacea L. (reedcanary grass) compared to planting on 1.41 m centers. Conversely, a less dense planting provided greater plant response (g rowth and viability) with Zostera marina L. (eelgrass) at 5 plants m -2 in an intertidal zone near Balgzand (Netherlands) (Bos & van Katwijk 2007). From the references above, it can be inferr ed that the optimal pl anting density required is a function of the eco system, the invader, and the nat ive species being planted. Propagule size is another important consideration to assure successful establishment of desired plants. Ratliff & Westfall (1992) found that 5.1 cm diameter plugs of Carex exserta had 52% greater survival over a 4 year study period than 1.9 cm diameter plugs of the same species bec ause greater root development decreased transplanting stress. Re storing with larger plants is likel y more costly than using small plugs due to associated labor and spac e requirements for plant production and handling. Little research has addressed the topic of propagule size as it relates to establishment success for other native plant communities. A greater degree of species richness in re storation projects is also an important consideration for revegetation efforts. Ecosystems constantly evolve to become resilient to disturbance (Cr opp & Gabric 2002) where changes in species composition are common (Walker et al. 1999). Species diversity increases the ability of an 19

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ecosystem to become more resilient at the community level (Steiner et al., 2006) and resistant to nonnative plant invasion (Stacho wicz et al. 2002; Hooper et al. 2005). However, some theorists have argued that ecosystems with high biodiversity are intrinsically unstable since species routinely appear and di sappear. Regardless of the stability of diverse systems, hi gh species richness is usually a common restoration goal since a large species pool is more likely to support a functioning ecosystem subjected to disturbance. Therefore, higher diversity revegetation efforts ar e more likely to result in ecosystems less prone to impact by potential future invasions and ecosystem degradation. Plant growth and development in aquatic and wetland sites is dependent upon water availability and thus planting locati on with respect to wate r depths. Native wetland species (e.g. Potamogeton pectinatus (L.) Berner (sago pondweed), Najas flexilis (Willd.) Rostk. & Schmid t (nodding waternymph), and Lemna spp. L. (duckweed)) are especially responsive to alterations in hydrology and hydr operiod, therefore, planting elevation should be a limiting factor (van der Valk 1981; Spence 1982). Budelsky & Galatowitsch (2000) showed that wa ter level conditions are most crucial during the first year of plant establishment because this is the time frame in which both growth and mortality is greatest. An understanding of the relative impor tance of factors that influence plant community establishment can only be conf irmed experimentally. Few studies have addressed this research need using multiple species, so generalizations across species may or may not be appropriate. In their study of two forbs native to wooded hay meadows, Wallin et al. (2009) found that for both species studied, plants were better 20

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established from plug-plants versus seed addi tion. However, for many ecosystems, particularly spatially heterogeneous wetlands, we expect species-specific differences with respect to optimum planting methods. Despite the benefits that active revegetation offers for ecosystem restoration, fo r many degraded ecosystems in which the restoration need is great, species-specific information on revegetation methods is lacking. Model Systems Freshwater Depression Marshes with in Everglades Marl Prairies Hydrologic alterations and fire suppressi on have led to major changes in the vast Everglades wetland ecosystem of south Florida, USA over the past century. Changes in plant community and structure result in degraded ecosystem health and a reduction of several species indigenous only to the Everglades. The Everglades are of considerable biodiversity value, containi ng a disproportionately large number of the worlds endangered and threatened specie s such as the Florida panther ( Felis concolor coryi ), the Cape Sable seaside sparrow ( Ammodramus maritimus mirabilis ) and several native orchids ( Oncidium spp., Cyrtopodium spp.). Therefore, removing invasive species would likely increase native specie s populations and could potentially prevent extinction. Hydrologic alteration in the Everglades includes channelization of the Kissimmee River and construction of the Central and Southern Florida Pr oject (McCoy et al. 2007) which protect agriculture and over 5 million peopl e. Alteration of fire regimes has also been considerable; the National Park Service rapaciously suppressed wildfires in the Everglades starting in 1947. Prescribed fires were reinstated in 1958 (Segar 2009) but the lower frequency and intensity has dram atically altered marshes and other 21

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ecosystems in the area by altering the plant populations which were not fire-adapted (Lodge 2005). Areas which were historically fr eshwater depression marshes have become dominated by Salix caroliniana (a native facultative wetland species which has become opportunistic) which has excluded native spec ies. Freshwater depression marshes within marl prairies occur only in sout h Florida (Whitney et al. 2004) and are characterized as shallow, rounded depressions in a sandy soil or subsurface hardpan and can either be permanent or temporary with hydrology ranging from 50 days per year (Florida Natural Areas Inventory and Florida Department of Natural Resources 1990). These marshes are composed of mesic species such as, asters ( Aster spp.), beaksedges ( Carex spp.), bluestems (Andropogon spp.), milkweeds ( Asclepias spp.), and lovegrasses ( Eragrostis spp.), as well as wetland species such as American white waterlily ( Nymphaea odorata Aiton), cypress ( Taxodium spp.), pickerelweed ( Pontederia cordata L., P. rotundifolia L.), sawgrass (Cladium spp.), arrowhead (Sagittaria latifolia Willd., Sagittaria lancifolia L.), spikerush (Juncus spp.), and starrush whitetop ( Rhynchospora colorata (L.) H. Pfeiffer), among other wetland species. Pine Flatwoods Pine flatwoods are the most extensive terrestrial ecosystem in Florida with very few virgin pine flatwoods left in existence. Pine flatwoods act as refuges for many faunal and floral species in cluding white-tailed deer ( Odecoileus virginianus ), the threatened Florida black bear ( Ursus americanus floridanus ), gopher tortoise ( Gopherus polyphemus ), the threatened redcockaded woodpecker ( Picoides borealis ) and Chapmans rhododendron ( Rhododendron chapmanii ). Pine flatwoods possess unique characteristics such as low, flat topography poorly drained, acidic soils, and frequent 22

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fires (every 4-10 years). These ec osystems are comprised of an open pine ( Pinus spp.) canopy, an extensive shrub layer, most commonly saw palmetto ( Serenoa repens (Bartram) Small ) but also gallberry ( Ilex glabra (L.) A. Gray ), fetterbush (Lyonia lucida (Lam.) K. Koch ), wax myrtle ( Myrica cerifera (L.) Small ), blueberries ( Vaccinium spp.), wiregrasses ( Aristida spp.), broomsedges ( Andropogon spp.), and sporadic forbs including, asters ( Aster spp.) and Catesbys lily ( Lilium catesbaei Walter). Flatwoods are often degraded as a re sult of phosphate mi ning, and required reclamation may fall short of restoring the flatwoods plant community. Former phosphate mines are characterized by increased soil distur bance, decreased biodiversity, and altered plant community co mposition (Manner et al 1984). Also, this ecosystem type has been compromised throughout the state of Florida because of extensive exotic plant invasions by Imperata cylindrica Lygodium spp, Sporobolus spp. (smutgrass), Cyperus spp., and several other weedy taxa. Anthropogenic results of pine flatwoods degradation include poaching of endangered plants, reduced prescribed burns, and undesirable species invasion. Imperata cylindrica was introduced accidentally as a packaging cushion for shipping cargo from Asia to America (1911) and later intentionally as a potential forage (1920s), and has became a noxious invasive ex otic. This species invades rapidly, forming monotypic stands that exclude nativ e species, especially during wildfire (Hubbard et al. 1944; Gaffney 1996). Effe ctive methods for initial control of I. cylindrica have been developed (applying 1.5% imazapyr in fall in conjunction with tilling), but revegetation efforts in pi ne flatwoods have not been researched (MacDonald 2004). 23

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Research Goals Determining optimum rev egetation methods may be crit ical to restoration of invaded freshwater marshes and pine flatwoods. This research investigates several aspects of revegetation following invasive s pecies removal in a mesic-xeric and hydric site. The first objective of this research will be to evaluate the effects of planting density, planting elevation, and propagule size on native plant establishment and survival in depression marshes at the Flor ida Panther National Wildlife Refuge. Two planting densities (dense and sparse), elevations (high and low), and propagule sizes (plug and container) will be analyzed to determine the effects of planting method for several species on native plant re-establishment. The second objective is to determine t he effects of planting species composition and subsequent chemical control of I. cylindrica on native species re-establishment at the Tenoroc Fish Management Area in Lakeland, Florida. Two planting regimes (high and low structural diversity) and herbicide applications (treated or untreated) will be evaluated to determine if structural dive rsity and subsequent herbicide control of I. cylindrica will suppress re-invasion. 24

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CHAPTER 2 REVEGETATING MARL PRAIRIE PONDS AFTER INVASIVE SPECIES REMOVAL Introduction Wetlands provide many functions in an ecosystem such as recycling nutrients, filtering pollutants, and prov iding habitats for endangered and pr otected flora and fauna. It follows that wetland degradation resulti ng from anthropogenic changes has been of major concern since the mid-twentieth century (Lodge 2005; McPherson & Halley 1996). The major effect of anthropogenic de velopment is alteration in hydrology and fire regime (Carrick & Kruger 2007; McPherson 1974) with south Florida providing a prime example (Lodge 2005). Everglades National Park and its surrounding wetland ecosystems, including Big Cypress National Preserve and Fakahatchee Strand Preserve State Park, are restoration focal areas for both researchers and practitioners. In these systems, altered disturbance regi mes have led to plant invasions that are significant in scope. For restoration of invaded ecosystems, in vasive species removal is often a key component of restoration goals and success. Invasive species alter ecosystem functions, values, and biodiversity by c hanging soil components, altering hydrology, outcompeting native species, and can act as catalysts to wildland fires (Lugo 2000; Carrick & Kruger 2007; Williams 2007). Upon large scale removal of invasive species, natural landscapes become disturbed resulti ng in safe sites for other undesirable invasive species (Johnstone 1986). Native species can act as a ba rrier to weed seed emergence if active revegetation strategies are implemented (Blum enthal et al. 2005) Revegetating an area upon removal of in vasive species encourages ecosystems to become more resilient to potential futu re alterations (Spiel es 2005). Rapidly 25

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establishing vegetation is often key to sa tisfying restoration contracts and mitigation requirements. Despite the crit ical nature of revegetation e fforts, factors that should be taken into account before initiating a re vegetation project are not well-known. Possible considerations for revegetation in clude planting density, species selection, planting elevation, and propagule size. Planting at greater densities may allo w for greater biodiversity and faster recolonization (Bos & Katwijk 2007). Alternat ively, sparser planting densities may allow for greater growth since plants are not as compact and competition is not as prevalent (Kim et al. 2006). In order to quickly es tablish a healthy, productive seedbank, using larger plant material (3-5 in ch pot size) compared to smalle r plant material (plugs from 72 count plug trays, approximately 2-inch di ameter cells) may be more desirable (Ratliff & Westfall 1992). Plants installed at higher el evations may have lower survivorship than plants installed at lower elevations since soil moisture is limiting at higher elevations due to the fluctuating water table (van der Valk 1981). To determine the effects of several fa ctors on native plant establishment and revegetation efforts in a south Florida wetland, two experiment s were initiated. The first experiment examined the effects of planting density and planting elevation on establishment of eight native wetland specie s. Experiment 2 examined the effects of propagule size and planting elevation on native plant establishment and growth. The ultimate goal of these studies is to provi de information pertinent to the development of revegetation protocols for fr eshwater depression marshes. 26

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Materials and Methods Study Site The Florida Panther National Wildlife Re fuge [FPNWR] is located near Naples, Florida in the Big Cypress Basin. Anth ropogenic alterations in ecosystem hydrology and fire suppression have led to a significant decrease in ecosystem function, value, and structure. As such, opportunistic species like Salix caroliniana Michx. (coastalplain willow) have colonized several freshwater depr ession marshes in marl prairies leading to a preclusion of native, desirable species. Two areas of focus at FPNWR have been documented through historic aerial photographs as formerly open-water depression marshes, or ponds, within the marl prairie. No published studies address restoration of Salix caroliniana -dominated wetlands, therefor e no information on revegetating freshwater depression mars h species is available. Site Preparation The two study ponds [(Pond 1 (lat 26.636 N, long 81.902 W) and Pond 2 (lat 26.773 N, long 81.077 W)] were su rveyed in January 2006 before developing the experimental studies. The following parameters we re assessed: extent of S. caroliniana invasion, soil nutrient status, current plant community composition, and seed bank composition (Adams et al. 2009). As suggested in the Comprehensive Conservation Plan for FPNWR (Krakowski et al. 1998), regrading the marshes is necessary to protect, restore, and manage fo r the following: (1) ca ndidate, threatened, and endangered species, (2) migratory bird s and their habitats, (3) wetlands and freshwater habitats, and (4) biodiversity. Salix caroliniana was removed from the site via excavation in January 2006 by FPNWR staff. 27

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Two separate experiments were im plemented in June 2007 to determine effectiveness of both planting de nsity and species size at two different elevations. Plots were placed at high (mean elevation= 0.9 m above water level) and low (mean elevation= 1.2 m above water level) elevations with respect to the littoral zones of the ponds. In order to measure water table location, monitoring wells were installed according to Soil Conservation Service (1993) guidelines. At time of planting (post-excavati on and regrading), both study ponds contained no vegetation. From Januar y 2008 to December 2008, Typha spp. (cattail) invaded Pond 1 and cover increased from 30% to >80% of the open water area (below the elevation of study plots). Because Typha spp. is opportunistic and grows densely in disturbed wetlands, it was critical to restorati on goals to control this invasive species. Glyphosate (3% solution of aquatic-labeled he rbicide) was applied on December 18, 2008 to invading Typha spp. Herbicide was appli ed when plants were entering dormancy, and translocation of carbohydrates in the downwar d direction was optimal for herbicide translocation to rhizomes. Plant Material Acquisition and Propagation The Guide to the Natural Communities of Florida, a comprehensive guide which classifies each natural community in Fl orida based on hydrology and vegetation, was used to determine species selection for revegetation in depression marshes. Depression marsh species for both experiments (8 species for experiment 1, 5 species for experiment 2, Table 2-1) were selected from a related seedbank assay (Adams et al. 2009) based on their wildlife value, likelihood of recolonizati on, wetland indicator status (facultative (usually occur (67-99%) in wetlands) or obligate (occurs almost always (99%) in wetlands) wetland species (United St ates Fish and Wildlife Service 1998) and 28

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potential for propagation. After species se lection, in February 2007, species were propagated via cuttings or division, placed in a fine-textured planting media (Fafard 2P Mix), moved to a misthouse for 3 weeks at mist intervals every 10 minutes, then hardened off in a temperature monitored greenhouse for 3 mont hs prior to installation (June 2007) in Gainesville, FL. Experimental Design Experiment 1: Effects of densit y and elevation on plant establishment Two parameters for Experim ent 1 were tested: effe cts of planting density and planting elevation on survival and growth. Three density treatments were tested: 1) dense [0.46 m between plants (1.5 ft centers) 48 plants per plot], 2) sparse [0.91 m between plants (3.0 ft centers) 24 plants per plot], and 3) control (unplanted). All density treatments were installed at two levels of elevation: high (1.2 m above water level) and low (0.9 m above water level). Plot sizes varied to accommodate plant material and spatial arrangement of treatments, such that dense plots were 9.5 ft x 12.5 ft (2.9 m x 3.81 m) and sparse plots were 11 ft x 17 ft (3.35 m x 5.18 m). Six and three specimens of each of the eight species were planted for dense and sparse treatment plots, respectively. Treatments were replicat ed five times for a total of 30 plots per pond and installed at both study ponds. Experiment 2: Effects of propagule size and elevation on plant establishment Two parameters for Experiment 2 were tested: the effe cts of planting elevation and propagule size on survival and plant volu me. Propagule size treatments consisted of: 1) 72-count plug tray size (2-inch diameter cells), 2) 5-inch diam eter pot size plants, or 3) unplanted (control) plots. These treatments were applied at two levels of elevation: high (1.2 m above water level) and low (0.9 m above water level). Plot dimensions were 29

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10 ft x 12 ft (3.04 m x 3.66 m) with density consis tent across treatments (plants installed at 1.5 ft centers, 0.457 m). Five individuals of five specie s were installed in each plot for a total of 25 plants per plot. Treatments were replicated three times for a total of 12 plots and installed at Pond 2 only, as Pond 1 size would not also accommodate space for this experiment. Data Collection Data were collected from June 2007 through June 2008. Plant volume and percent survival data were collected at time of planting, as well as 6 and 12 months after planting. Plant volume (m 3 ) was measured using a three-dimensional measuring device constructed from PVC. Percent su rvival was measured by locating planted individuals and observing them as alive (green shoots present) or dead. Species richness (quantity of species) data were collec ted at zero, three, six, and 12 months after planting by visually counting the number of species present in each treatment plot. Water table depth data were collected from the installed wells 6 and 12 months after planting. Soil samples were obtained afte r excavation, at time of planting, and 18 months after planting using a tu lip bulb planter to extract the top 5 cm of soil, placed in plastic zip bags, and transported on ice to prev ent fungi or mold from accumulating. Soils were analyzed at the Analytical Resear ch Laboratory (ARL) at the University of Florida for phosphorus, total Kjeldahl nitrogen (TKN), NO 3 -N, organic matter, and pH. Statistical Analyses Data were analyzed using Statistical Analysis Software (SAS) version 9.1.3 (SAS Institute Inc. 2004). For Experiments 1 and 2, analysis of variance (ANOVA) was used to assess main effects and interactions, and means were compared using the Least Significance Difference (LSD) procedure at p < 0.05. 30

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Results All species planted in both experiments had greater than 20% survival, and some had near 100% survival. The effects of all treatments (elevation, planting density, propagule size) significantly affected plant vo lume and survival. However, there were species-specific exceptions to the general trends. For both experiments, plant volume generally increased while surviv al generally decreased over the 12 month study period. At the time of planting (June 2007), water levels were excessively low due to a regional drought. Throughout the study period, water availability (depth to water at planting elevations) in both ponds varied wit h the seasonal pattern of precipitation (Figure 2-1). Although elev ation treatments in each pond were initially set at hydrologically equivalent levels with res pect to water table height, depth to water measurements were not equivalent across ponds, such that depth to water table differed significantly between parallel treatments (ANOVA F pond =3.56, p=0.04). Soils data reveal that soil quality was low in both ponds. Over time, pH levels did not vary. However, total nitrogen levels dec reased by almost 6 times over an 18 month period. Organic matter levels also decreased over 30 month period by almost 9 percent (Table 2-2). Experiment 1 Effects of Planting El evation and Planting Density on Percent Survival and Plant Volume Overall, plant volume (Table 2-3) wa s greater at sparse planting densities (p 0.01) across species. Overall percent survival (Table 2-4) was not affected by planting density (p=0.14). Plant volume was greater at lower planting elevations (p=0.01), but again did not affect overall perc ent survival (p=0.41) for all species. Species-specific responses to treatments are summarized by species in Figures 2-2 31

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through 2-9. Below, we detail the overall effect of each factor tested, focusing on 12 months after planting. Effects of elevation At 12 months after planting, both Cyperus haspan (Figure 2-2) and Fuirena breviseta (Figure 2-4) had greater plant vo lume at the lower elevation (p < 0.01), but Pluchea rosea (Figure 2-6) had greater volume at the sparse density at higher elevation (p=0.03); whereas Proserpinaca palustris (Figure 2-7) had great er volume at both sparse density and low elevation (p density =0.01, p elevation =0.44). For all other species, changes in volume over time differed wit h respect to a combination of planting treatments, but in most cases, elev ation had little impact on plant volume. Overall survival was higher at the high elevation for Proserpinaca palustris (Figure 2-7) and Rhynchospora colorata (Figure 2-8). For all ot her species, planting elevation had little effect on survival. Surviv al decreased over time at high elevations for C. haspan (Figure 2-2), F. breviseta (Figure 2-4), and V. hastata (Figure 2-9). At lower elevations, survival decreased over time for F. breviseta but either remained the same or increased for most other species. Effect of planting density At 12 months after planting, volume was greater at sparse densities for all species except Eleocharis atropurpurea (p=0.17), C. haspan (p=0.91), and F. breviseta (p=0.76) (Figures 2-3, 2-2, and 2-4, respectively). Survival was also greater at sparse densities for P. palustris (p=0.03) and V. hastata (p=0.01), but greater at higher densities for R. colorata (p=0.03). For the other five s pecies, survival was similar at both planting densities. 32

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Proserpinaca palustris and E. atropurpurea volume decreased over time in dense planting treatments. Eleocharis atropurpurea volume also decreased over time in sparse planting treatments. On the cont rary, volume increased at sparse planting densities over time for P. rosea P. palustris, R. colorata, and V. hastata. Survival in sparse planting densities increased or remained the same over time for P. rosea J. polycephalos P. palustris, R. colorata and V. hastata. Survival of all other species either remained the same or decreased ov er time at sparse planting densities. Effects of elevation and planting density on species richness Species richness was not affected by el evation (p=0.54) or density (p=0.56) at either pond (Table 2-5 and Fi gure 2-10), however, pond was si gnificant (p=<0.01). All unplanted plots had no species at time of pl anting, where planted plots contained the 8 planted study species at time of planting. More species were discovered at Pond 2 for unplanted and dense treatments during the study period but only for 6 through 12 months after planting for spar se treatments. Species ric hness increased rapidly in all treatments in the first three m onths after planting (at this poi nt, control plots contained at least 3 or more species compared to plant ed plots). After this increase, species richness gradually leveled off for the rest of the study period. Considering only densely planted plots, Pond 2 had 8 more species per plot than Pond 1 six months after planting. The highest levels of species richness (18 species) observed were in unplanted plots 3 months after planting. At 12 months after planting, species richness ranged from 8-15 species (Table 2-11). 33

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Experiment 2 Effects of Planting Elevation and Plant Size on Percent Survival and Volume Overall, volume (p=0.68) and survival (p =0.11) did not differ with elevation, but did differ with propagule size (Tables 2-6 and 2-7). Volume (p 0.01) and survival (p=0.01) were greater for 5-inch po tted plants for all species except V. hastata (regardless of planting elevation). Specie s-specific responses to treatments are summarized by species in Figures 2-11 thro ugh 2-15. Below, we detail the overall effect of each factor tested. Effects of elevation At 12 months after planting, planting el evation did not affect volume for all species except P. rosea (p=0.0453) where lower elevati ons provided for greater growth (Figure 2-13). The volume of P. palustris decreased over time at high elevations for 5inch potted plants (Figure 2-14) Conversely, volume increas ed at low elevations for the same species and plant size. All other s pecies increased in volume over time regardless of elevation or plant size. Survival was greater for V. hastata (p=0.0353) at higher elevations both 6 and 12 months afte r planting (Figure 2-15). For all other species, survival varied with time and plant size. Effects of propagule size For all species except P. palustris and V. hastata volume (p 0.01) was greater for 5-inch potted plants. At higher elevations, volume was greater for P. palustris and V. hastata as plug-plants, but at lower elevations, volume was greater as 5-inch potted plants. Survival was greater than 70% for all species except P. palustris and V. hastata both 6 and 12 months after planting at either elevation and planting size. 34

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Effects of elevation and propa gule size on species richness Species richness was not affected by any factor tested ex cept propagule size (Table 2-8). Regardless of propagule size, s pecies richness increased in planted plots past 3 months after planting. Unplanted plot s increased in species richness from initial time of planting to 3 months after planting by almost 20 species, but over time, species richness decreased in unplanted plots and eventually leveled off at or below 12 species per plot (Figure 2-16; Table 2-12). Discussion Establishment of native species follo wing invasive species removal can be accomplished with a multi-species planting. However, results also show that following species-specific guidelines will maximize establishment, and that consideration of several factors in planting methods can signifi cantly increase revegetation success. As an example, for 5-inch potted plants, P. palustris and V. hastata had 80% greater plant volume at low elevation than high elevation during the final data collection period. Because conditions following invasive spec ies removal present many barriers for native species establishment, selecting t he appropriate plants with respect to water table and other environmental criteria is particularly important to establishing a successful plant community. In this study, planting at the co rrect elevation can increase plant survival significantly. For instanc e, planting an obligate wetland species like P. palustris at low elevations (with increased water availability) resulted in 1.5 times the survival than at high elevations for this spec ies. With greater disparity in elevation treatments, more species-spec ific preferences for high or low elevation planting would have been observed given the differences in pl ant response found at this relatively 35

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small variation in elevation. Also, several of the species selected have a fairly broad elevation range. Revegetation experiments such as the two performed in this project may be useful for land managers and re storation practitioners who ex ecute large scale wetland restoration projects. To communicate species-specific planting recommendations, perhaps categorizing species based on treatment s that resulted in the most successful establishment is optimal. As an example, see Tables 2-8 and 2-9 that reflect the relative importance for each factor to est ablishment of species tested in this study. Hydrology and Elevation Drive Establishment Hydrology is a key determinant for plant community development and patterns of plant zonation (Finlayson & Mitchell 1999). This is particularly true for emergent wetland plants, which are best suited for anox ic soil conditions while foliage remains above water (van der Valk 1994). Due to this adaptation, insufficient soil moisture may be the most common reason for wetland reveget ation failure. Experiments with newly establishing seedlings have shown that drought stress was an important cause of decreased seedling survival rates (Rood et al. 2008). From this body of research, it was expected that hydrology would be a critical factor to plant establishment and success. Water levels in the study ponds varied within season (according to expected seasonal precipitation patterns) but also we re highly variable during the study period. At time of planting (June 2007) water levels were 90 cm and 120 cm to water table at low and high elevations, respectively, indica tive of drought conditi ons. Despite setting high elevation treatments at equivalent elevations initially, high elevations in Pond 2 were drier than those in Pond 1. Abiotic char acteristics related to water retention (e.g. soils, basin morphology) may have differed in the ponds, such that although ponds had 36

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equivalent hydrology initially, Pond 2 retained more water over time. During the fall and winter months (September-February) over the entire study period, however, ponds experienced somewhat similar hydrologic condi tions, as the entire st udy area of both ponds was inundated. Species hydrologic response was associ ated with typical patterns of occurrence in wetlands: plant volume was greater for ob ligate wetland species at low elevations and for facultative wetland species at higher elevat ions (Figures 2-2 through 2-9). This is to be expected since obligate wetland specie s rely more on a semi-permanent permanent water source whereas facultative wetland species thrive in a more transitional water gradient (Uni ted States Fish and Wildlife Service 1988). There were some surprising results, e.g. survival was greater for some facultative wetland species at low elevations, but at hi gh elevation obligate wetland spec ies survival was greater. This suggests there is an el evation gradient in which hydrologic niches for both facultative and obligate wetland species overl ap. A relatively small difference in elevation was tested, perhaps en compassing this niche, and therefore it is cautioned that if a greater range in el evation was chosen, more spec ies-specific preferences may have been detected. Revegetation was generally successful ( despite drought conditions at time of planting) in that pl ant volume increased throughout the study period for all species. Eleocharis atropurpurea was one exception. One reason E. atropurpurea volume decreased is because this species is an annual (other species used were perennials) and senescence of planted individuals may have occurred between the 6 and 12 months after planting observation periods. 37

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Despite the increasing trend in volume, percent survival showed a more complicated response. Survival fluctuated over time, but consistently declined in the first 6 months after planting for all species. Ponds were severely dry as a result of the summer 2007 drought during the initial establishment period, likely causing the decrease in survival at 6 months after planti ng. It is important to note, however, that over time precipitation gener ally increased, inundating both ponds and resulting in complete submergence of all planted species which caused some specimens to die. In some instances, specimens were recorded as dead in response to receding water levels, but eventually emerged with new growth. Therefore higher levels of survival were observed at 12 months than at 6 months after planting. The Role of Planting Dens ity and Propagule Size It is assumed that revegetating with larger plants results in greater likelihood of establishment because larger plants are har dier and more resistant to environmental stress since the root stru cture is more developed (St eed & Dewald 2003), whereas smaller-sized plants require more ideal condit ions. Similarly, planting at high densities is thought to be optimal becaus e of the nurse-plant concep t: a member of one species facilitates the growth of anot her species by ameliorating the stressors of the local environment (decreasing soil evaporation ra tes, decreasing microsite temperatures causing less evapotranspiration in foliage) (Niering et al. 1963; Raffaele & Veblen 1998). Revegetation projects are primarily constrained by budget. Reducing cost, either by planting in lower densities, or by using smaller plug plants, would be an important increase in cost efficiency, if eit her of these strategies resulted in successful establishment. 38

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Results showed plant volume was generally higher at sparse densities, possibly because of a lack of competition (fewer indi viduals competing for scarce resources). Budelsky et al. (2000) also f ound that at low planting densit ies, sedges obtained greater volumes due to reduced competition. Not only is planting at lower densities more costeffective than higher densities, but this lower-cost option actually results in greater volume of establishment. As expected, most species utilized in this experiment grew larger installed as 5inch potted plants. This difference is not likel y to be related only to the larger initial size of the propagules; rather, the 12 month study period is sufficiently long enough to afford plug plants the opportunity to reach volumes equiva lent to that of 5-inch potted plants. The intense water stress experienced by st udy plants during the initial planting may have provided the 5-inch potted plants wit h an advantage, because the more developed root system in these plants allowed fo r increased water absorption capacity. Proserpinaca palustris and V. hastata were exceptions to this trend in that 5-inch potted plants did not consistent ly outperform plugs. Complicating this result is that initial P. palustris volume was equivalent in both plug-pl ants and 5-inch potted plants, likely a result of its prostrate grow th habit, therefore it might be expected that there was no difference in performance due to in itial propagule size. Regarding V. hastata overall survival rates were so low (0-65%) that few plants were measurable, resulting in considerable variability in plant volume, and difficulty detecting preferences for this species. Although the experiment did not provide a generalized recommendation for propagule size across all species, results show that when developing revegetation 39

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plans, for certain species, establishment from plug plants may be as cost-effective as or better than establishment from large plants. Comparing Planting to Natural Recolonization High plant community species richness is often an important restoration goal. This parameter provided insight into the utilit y of the planting methods tested, and also revealed some interesting site-to-site differences in natural recolonization. Species richness varied over time and between ponds. Surprisingly, species richness did not differ within de nsity or elevation treatments, despite the fact that establishment is highly dependent upon hydrol ogic regime (Casanova & Brock 2000). Pond 2 had higher species richness than Pond 1 across treatments. One key difference in post-planting pond species co mposition is the cover of B. caroliniana which was 10% or less in Pond 2, compared to 60% in Pond 1. Dense mats formed by this herbaceous perennial (Villazon 2009) are likely to preclude other species and therefore may contribute to the low species richness observed in Pond 1. Results point out that si te differences offer another potential explanation for differences in species composition between ponds. Site-to-site variabili ty (e.g. in extant adjacent vegetation) may have a strong infl uence on revegetation patterns, even when restoration locations are semi-contiguous. Pond 1 was surrounded by a high pineland (e.g. Serenoa repens, Pinus spp., various herbaceous perennials, Lodge 2005), whereas Pond 2 was surrounded by sawgrass marsh (e.g. Crinum americanum, Eleocharis cellulosa Sagittaria lancifolia Cladium jamaicense ). The high pineland may have limited anemochorous dispersal into Pond 1 since lower cover of several wind dispersed species (e.g. Eupatorium capillifolium Typha sp., Echinochloa crusgalli ) was noted. 40

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Percent cover of species that natura lly recolonized was generally similar in planted and unplanted plots (Tables 2-11 and 212). Research has shown that active revegetation using propagules larger than seeds (rhizomes, stakes, plants) increase the likelihood of greater species richness (De St even &Sharitz 2007). While the plantings in this study did not increase species richness, it also did not limit recruitment from unplanted species. Restoration Trajectories Advancement of restoration from an unrestored, sometimes disturbed, ecosystem to the desired recove ry state can be viewed as a restoration trajectory (Baer et al. 2004). Recent reviews suggest that t hese trajectories are rarely born out of observations of restored wetlands over time (Zedler & Callaway 1999). Although many outcomes are possible for these depression ma rshes, the previous observations provide some insight into potential development of these ecosystems. For instance, the data suggest that over time, dense colonization of B. caroliniana in Pond 1 may exclude colonization of other species, and limit specie s richness. In contrast, in Pond 2, limited B. caroliniana cover may result in overall greate r species richness. Despite the emergence of several trends, for many response variables (survival, volume) there were no consistent trends in development, supporting the contention that trajectories may not exist, or may not be observable under a typica l monitoring period for any project (1-3 years). Soils, particularly pH, NO 3 and organic matter, are an important component to any restoration project involving active revegetation, and there were degraded soil conditions at time of planting. Continual decreases in organic matter levels from time of regrading to 12 months after in itial planting may be a result of exposure of the lower soil 41

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horizons due to the invasive species removal and removal technique (Ugen & Wortmann 2001). Since TKN decreased by almo st 75%, plant growth may be limited by nitrogen availability in these systems. Unfo rtunately, slow growing vegetation in these restored marshes means that there may be a considerable lag before the organic matter layer results in humus creation. The potential exists for invasive species to limit plant community development at these sites. Native plant arrival and establishment in prairie pothole wetland restorations is limited over the long te rm by the invasion and persistence of Phalaris arundinacea (Aronson & Galatowitsch 2008). Similarly, invasion of Typha spp. (likely angustifolia ) may limit further colonization or persi stence of existing native species in these restorations. Control of this in vasive species was necessary during the experimental period to maintain the restoration goal of an open water system (Holm et al. 1997; Mitich 2000) and may be necessary if and when future reinvasion occurs. Conclusions: Implications for Practice Since propagule size had sign ificant impact on survival for all species except L. alatum, revegetating areas using 5-inch pott ed plants is recommended to reduce the necessity for a second planting, increase in itial ground cover and biodiversity. Use of V. hastata is not recommended since survival of this species was low. Three species recommended for revegetating a marl-prairie pond are L. alatum, E. atrpourpurea and P. rosea because they generally establish well in all circumstances. If planting at sparse densities, using J. polycephalos and P. rosea C. haspan, E. atropurpurea, F. breviseta is recommended since survival of these species was unaffected by density. 42

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Invasion of Typha spp. could be a potential problem while attempting to restore an open water pond and removal the species is likely critical to maintaining an open water pond. Because significant changes in plant community composition and cover were observed in the 1 year study period, it is likely that further development of the plant community will occur in these restorations over the next dec ade or longer, and therefore monitoring and subsequent invasive species management is recommended. 43

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Table 2-1. Species used for revegetation in both experiments. Experiment 1 Experiment 2 Wetland status* Bacopa caroliniana (Walter) B.L. Rob. (waterhyssop) OBL Cyperus haspan L. (haspan flatsedge) OBL Eleocharis atropurpurea (Retz.) J. & K. Presl. (purple spikerush) OBL Fuirena breviseta Coville (saltmarsh umbrella-sedge) OBL Juncus polycephalos Michx. (manyhead rush) OBL Lythrum alatum Pursh. variety lanceolatum (Ell.) T. & G. Rothr. (winged loosestrife) OBL Pluchea rosea Godfrey (rosy camphorweed) Pluchea rosea Godfrey (rosy camphorweed) FACW Proserpinaca palustris L. (marsh mermaidweed) Proserpinaca palustris L. (marsh mermaidweed) OBL Rhynchospora colorata (L.) H. Pfeiffer (starrush whitetop) FACW Verbena hastata L. (swamp verbena) Verbena hastata L. (swamp verbena) FACW OBL= obligate, FACW= facultative wetland. 44

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45 Table 2-2. Soil analysis for both ponds afte r regrading, at time of planting, and 18 months after planting. Soil collection date P (mg/kg) pH TKN (mg/kg) NO 3 -N (mg/kg) OM(%) After regrading (January 2006) 0.24 7.7 17.54 13.10 Planting date (June 2007) 8.0 2846 6.59 7.95 December 2008 0.29 7.9 561 2.66 4.61

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Table 2-3. Analysis of variance for effects of planting density, elevation, m onths after initial planting, and pond location on plant volume and for each of the eight species planted. Overall volume Cyperus Eleocharis Fuirena Juncus Pluchea Proserpinaca Rhynchospora Verbena Source F P F P F P F P F P F P F P F P F P Density 28.8 <0.01 0.0 0.90 2. 7 0.10 0.1 0.76 8.2 0.01 4.9 0. 02 8.5 0.01 22.2 <0.01 6.7 0.01 Elevation 8.4 0.01 15.2 0.01 1. 8 0.17 41.4 <0.01 1.0 0.31 4.7 0.03 0.6 0.44 1.3 0.24 0.0 0.93 Density*elevation 0.8 0.36 0.0 0. 94 0.3 0.57 0.2 <0.01 1.6 0.20 4. 3 0.03 3.1 0.07 0.1 0.72 0.0 0.92 Pond 4.0 0.04 13.1 0.01 22.3 <0. 01 49.2 0.69 0.5 0.46 0.0 0.87 1.1 0.27 1.9 0.16 3.7 0.05 Density*pond 0.1 0.70 0.0 0.97 0.2 0.67 0.2 <0.0 1 1.3 0.26 4.6 0.03 8.3 0.01 0.0 0.86 1.1 0.29 Elevation*pond 9.4 0.01 1.2 0.27 2.7 0.10 8.3 0.01 14.9 0.01 0.0 0.86 1.2 0.25 0.0 0.90 2.2 0.13 MAP 957.5 <0.01 84.7 <0.01 17.4 <0.01 193.3 <0.01 222. 2 <0.01 29.9 <0.01 1.4 0. 23 453.9 <0.01 5.8 0.01 Density*MAP 25.2 <0.01 0.1 0.80 0.3 0.62 0.8 0. 35 6.3 0.01 3.9 0.04 6.3 0.01 18.2 <0.01 5.6 0.01 Elevation*MAP 4.3 0.03 8.9 0.01 0.7 0.39 37.3 <0.01 0.1 0.75 1.7 0.18 1.2 0.25 5.7 0.01 0.2 0.63 Pond*MAP 8.6 0.01 7.8 0.01 48.7 <0.01 46.3 <0.01 1 .1 0.29 5.7 0.01 13.4 0.01 1.6 0.20 4.7 0.03 46

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47 Table 2-4. Analysis of variance for effe cts of planting densit y, elevation, months after in itial planting, and pond location o n percent survival overall and for each of the eight species planted. Overall survival Cyperus Eleocharis Fuirena Juncus Pluchea Proserpinaca Rhynchospora Verbena Source F P F P F P F P F P F P F P F P F P Density 2.1 0.14 0.1 0.78 0.1 0.77 0.0 0.98 1.8 0.18 1.0 0.31 4.8 0.03 4.6 0.03 12.3 0.01 Elevation 1.1 0.28 4.8 0.02 0. 3 0.58 3.1 0.07 2.8 0.09 0.0 0. 92 7.0 0.01 12.7 0.01 1.8 0.17 Density*elevation 30.7 <.01 0.1 0.78 17.5 <0.01 5.9 0.01 3.1 0.07 4.6 0.03 4.6 0.03 3.9 0.05 2.5 0.11 Pond 39.9 <.01 0.8 0.36 0.3 0.58 0.4 0.54 2.0 0.15 0.0 0. 88 0.1 0.78 7.4 0.01 187.3 <0.01 Density*pond 2.4 0.12 1.9 0.16 5.0 0.02 5.2 0. 02 0.4 0.50 0.3 0.56 0.0 0.94 0.2 0.65 1.4 0.24 Elevation*pond 2.0 0.15 6.6 0.01 2.7 0.09 8.3 0.01 1.1 0.28 6.5 0.01 7.6 0.01 0.3 0.56 0.2 0.65 MAP 5.6 0.01 0.7 0.38 0.3 0.58 1.3 0.25 5. 3 0.02 10.8 0.01 1.0 0.32 15.2 0.01 14.1 0.01 Density*MAP 4.1 0.04 0.5 0.46 1.1 0.28 8.4 0. 01 0 0.98 0.0 0.95 12.7 0.01 0.1 0.70 10.9 0.01 Elevation*MAP 0.3 0.56 1.6 0.20 10.9 0.01 12.0 0 .25 2.8 0.09 0.2 0.67 4.7 0.03 9.0 0.01 1.8 0.17 Pond*MAP 0.1 0.85 10.4 0.01 1.2 0.27 0.0 0.98 8.6 0.01 0.2 0.67 2.9 0.09 0.0 0.87 58.8 <0.01

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48 Table 2-5. Analysis of variance for effect s of planting density and planting elevation on species richness. Source F P Elevation 0.38 0.5385 Pond 17.53 <0.0001 Elevation*pond 0.02 0.8904 Density 0.58 0.5597 Elevation*Density 0.86 0.4269 Pond*Density 1.96 0.6182 MAP 19.59 <0.0001 Elevation*MAP 1.50 0.2266 Pond*MAP 5.25 0.0063 Density*MAP 3.26 0.0137

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Table 2-6. Analysis of variance for effe cts of propagule size, elevation, and months after initial planting, on overall plant volume and for each of t he five species planted. Overall volume Bacopa Lythrum Pluchea Proserpinaca Verbena Source F P F P F P F P F P F P Propagule size 22.62 <.0001 57.97 <0.0001 53.54 <0.0001 43. 41 <0.0001 2.98 0.0903 0.04 0.8533 Elevation 0.16 0.6867 0.12 0.7309 0.02 0.8976 4.10 0.0453 1.24 0.2697 1.76 0.2023 Propagule size*elevation 0.01 0.9413 1.27 0.2619 0.19 0.6664 0.44 0.5109 0.23 0.6367 1.10 0.3093 MAP 34.71 <.0001 72.11 <0.0001 74.77 <0.0001 88.75 <0.0001 0.17 0.6789 0.93 0.3490 Propagule size*MAP 15.14 0.0001 22.88 <0.0001 44.97 <0.0001 43. 16 <0.0001 0.65 0.4226 0.00 0.9638 Elevation*MAP 0.14 0.7087 .0 .49 0.4867 0.00 0.9875 4.78 0.0 310 1.26 0.2673 0.42 0.5271 49

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50 Table 2-7. Analysis of variance for e ffects of propagule size, elevat ion, and months after initia l planting on overall percent survival and for each of t he five species planted. Overall survival Bacopa Lythrum Pluchea Proserpinaca Verbena Source F P F P F P F P F P F P Propagule size 14.22 0.01 9.95 0.01 1. 05 0.31 6.75 0.01 4.16 0.04 13.13 0.01 Elevation 2.61 0.10 0. 12 0.72 3.01 0.08 2.95 0. 08 0.27 0.60 4.54 0.03 Propagule size*elevation 0.81 0.36 0.12 0.72 6.03 0.01 3.00 0.08 0.02 0.87 0.25 0.61 MAP 0.00 1.00 14.86 0.01 0.14 0.70 0.74 0.39 0.34 0.56 22.58 <0.01 Propagule size*MAP 3.22 0.07 9.95 0.01 0.14 0.70 0.75 0.38 0.05 0.82 9.48 0.01 Elevation*MAP 0.13 0.71 0.12 0.72 0.10 0.74 0.00 1.00 2.64 0.10 2.06 0.15

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51 Table 2-8. Analysis of variance for effe cts of planting elevat ion and propagule size on species richness. Source F P Elevation 1.84 0.1768 Size 16.65 <0.0001 Elevation*Size 0.82 0.4442 MAP 12.17 <0.0001 Elevation*MAP 4.96 0.0083 Size*MAP 19.48 <0.0001

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Table 2-9. Species-specific plant vo lume response to planting treatments. Elevation Density High Low No preference in elevation Dense Sparse Pluchea rosea Juncus polycephalos Proserpinaca palustris Rhynchospora colorata Verbena hastata No preference in density Cyperus haspan Fuirena breviseta Eleocharis atropurpurea 52

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53 Table 2-10. Species-specific percent su rvival response to planting treatments. Elevation Density High Low No preference Dense Rhynchospora colorata Sparse Proserpinaca palustris Verbena hastata No preference Cyperus haspan Eleocharis atropurpurea Fuirena breviseta Juncus polycephalos Pluchea rosea

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Table 2-11. Percent cover and species com position of naturally recolonizing species and their frequency of occurrence 12 months after planting for effects of planting density and pl anting elevation on species response. Percent cover (%) Planted plots* Unplanted plots** Species Pond 1 Pond 2 Pond 1 Pond 2 Bacopa caroliniana 50 10 70 10 Pluchea rosea 20 25 5 30 Proserpinaca palustris 10 <5 10 <5 Rhynchospora colorata 20 45 5 10 Cyperus haspan 10 15 5 <5 Fuirena breviseta 10 15 10 <5 Juncus polycephalos 5 15 <5 <5 Eleocharis atropurpurea 20 10 20 <5 Ludwigia repends 65 30 65 45 Lythrum alatum 30 20 35 20 Acmella spp. 10 0 <5 0 Mikania scandense 20 <5 20 <5 Ludwigia microcarpa 45 10 40 5 Eupatorium capillifolium <5 25 <5 30 Saigattaria lancifolia 10 <5 5 <5 Typha spp. 30 0 30 0 Echinochloa crus-galli <5 0 <5 0 Salix caroliniana 0 <5 0 <5 Solidago spp. 0 <5 0 <5 Mitreola sp. 0 <5 0 5 Lobelia feayana 0 <5 0 <5 Mean of 40 plots ** Mean of 19 plots 54

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55 Table 2-12. Percent cover and species com position of naturally recolonizing species and their frequency of occurrence 12 months after planting for effects of planting elevation and propagule size on plant response. Percent cover (%) Species 5-inch potted plant* Plug-plant Unplanted** Acmella spp. <5 0 0 Bacopa caroliniana 10 <5 10 Eupatorium capillifolium <5 30 30 Juncus polycephalos <5 <5 <5 Ludwigia microcarpa 45 <5 5 Ludwigia repens <5 65 45 Lythrum alatum 70 30 20 Mikania scandens <5 0 <5 Pluchea rosea 35 10 30 Proserpinaca palustris <5 <5 <5 Verbena hastata 15 <5 <5 Bare soil 75 >95 55 Mean of 6 plots ** Mean of 10 plots

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56 Figure 2-1. Depth to water table was m easured using a laser level at time of pl anting and installed wells thereafter at either planting elevation. Precipitat ion data also shown over data collectio n period (for elevation data, mean of water table height at 3 wells and standard error are shown).

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Figure 2-2. Cyperus haspan the effects of planting elev ation and planting density on plant volume and percent survival. Mean of 10 replicat ions followed by standard error; n=30 for sparse planting, n=60 for dense planting. 57

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Figure 2-3. Eleocharis atropurpurea the effects of planting elevation and planting density on plant volume and percent su rvival. Mean of 10 replications followed by standard error; n=30 for sparse planting, n=60 for dense planting. 58

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Figure 2-4. Fuirena breviseta the effects of planting elev ation and planting density on plant volume and percent survival. Mean of 10 replications followed by standard error; n=30 for sparse planting, n=60 for dense planting. 59

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Figure 2-5. Juncus polycephalos the effects of planting el evation and planting density on plant volume and percent survival. Mean of 10 replications followed by standard error; n=30 for sparse planting, n=60 for dense planting. 60

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Figure 2-6. Pluchea rosea the effects of planting elevation and planting density on plant volume and percent survival. Mean of 10 replicat ions followed by standard error; n=30 for sparse planting, n=60 for dense planting. 61

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Figure 2-7. Proserpinaca palustris the effects of plantin g elevation and planting density on plant volume and percent su rvival. Mean of 10 replications followed by standard error; n=30 for sparse planting, n=60 for dense planting. 62

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Figure 2-8. Rhynchospora colorata the effects of planting elevation and planting density on plant volume and percent su rvival. Mean of 10 replications followed by standard error; n=30 for spar se planting, n=60 for dense planting. 63

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Figure 2-9. Verbena hastata the effects of planting el evation and planting density on plant volume and percent survival. Mean of 10 replicat ions followed by standard error; n=30 for sparse planting, n=60 for dense planting. 64

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65 Figure 2-10. Effects of planting density on species richness at either study pond for Experiment 1. Mean of 10 replications followed by standard error.

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Figure 2-11. Bacopa caroliniana the effects of planting elevation and propagule size on plant volume and percent survival. 66

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Figure 2-12. Lythrum alatum the effects of planting elev ation and propagule size on plant volume and percent survival. Mean of 3 replications follo wed by standard error, n=5. 67

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Figure 2-13. Pluchea rosea the effects of planting elevation and propagule si ze on plant volume and percent survival. Mean of 3 replications follo wed by standard error, n=5. 68

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Figure 2-14. Proserpinaca palustris the effects of planting elevation and pr opagule size on plant volume and percent survival. Mean of 3 replications followed by standard error, n=5. 69

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Figure 2-15. Verbena hastata the effects of planting elevat ion and propagule size on plant vo lume and percent survival. Mean of 3 replications follo wed by standard error, n=5. 70

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71 Figure 2-16. Effects of propagule size on species richness for Experiment 2. Mean of 3 replicat ions followed by standard error.

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CHAPTER 3 RESTORATION OF PINE FLATWOODS IN FLORIDA UPON REMOVAL OF COGONGRASS ( IMPERATA CYLINDRICA ) Introduction Florida is one of the worlds largest producers of phosphate because of its rich and easily accessible deposits (Jasinksi 1999). Phosphate is actively mined in Polk, Hamilton, Hillsborough, Har dee, and Manatee counties in Florida (Tamang et al. 2008), where removal of the top 15 to 50 feet of the soil surface results in significant soil disturbance. Th is alteration in soil properties generally supports mainly opportunistic plant species, such as Schinus terebinthifolius Raddi. (Brazilian pepper), Sporobolis indicus (smutgrass), and Ludwigia peruviana (L.) H. Hara (primrose willow), which bec ome problematic. Largescale removal of these invasive species often leads to further disturbed and barren soils, which may result in safe si tes for invasive species establishment (Johnstone 1986). Such removal of target invasive species from an ecosystem can lead to either a moonscape or in troduction of another undesirable invasive species which can result in monotypic st ands if revegetation strategies are not implemented (Ogden & Remanek 2005; Shilling et al. 1997). A major invasive species concern in post-mining sites is Imperata cylindrica (L.) Beauv. (cogongrass) (Coile & Shilling 1993), w here broad-scale control methods are often implemented for this spec ies, but these efforts rarely result in return of the native flatwoods plant community (MacDonald 2004). Imperata cylindrica : Biology and Morphology Imperata cylindrica is an example of a federally listed noxious weed which requires extensive control efforts especia lly in post-mining areas (Ramsey et al. 72

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2003). This rhizomatous, pyrophilous, invasive exotic is listed as one of the worlds top ten worst weeds (Lum et al. 2005), and is problematic on every continent of the worl d except Antarctica (Holm et al. 1977). Imperata cylindrica was introduced accidentally as a packaging cushion for shipping cargo from Asia to America (1911) and later intentionally as a potent ial forage (1920s), and has became a noxious invasive exotic. This species rapidly invades both disturbed and undamaged flatwoods (Collins 2005), fo rms monotypic stands, and excludes native species (Lippincott 1997), especially during wildfire (Hubbard et al. 1944; Gaffney 1996). Holm et al. (1977) and Brook (1989) speculate that I. cylindrica spread is positively correlated with degree of site disturbance. Growing in compacted tufts, I. cylindrica arises from underground rhizomes which can extend up to 10 feet (Bryson & Carter 1993). Since more than 60% of the plant biomass consists of cataphyllous rhizomes (Ayeni 1985), management and control proves difficult. Imperata cylindrica rhizomes can be found in fine textured or coarse textur ed soils at depths of 15 cm and 40 cm, respectively and optimally grow at pH of 4.7 (Holm et al. 1977; Gaffney 1996; MacDonald 2004). Ayeni & Duke (1985) re ported that regenerat ive capacity of these rhizomes increased with rhizome age, but showed very little correlation between rhizome length and weight. Re search suggests that, after apex removal, auxin-imposed apical dominance allows axillary buds to maintain dormancy after applications of IAA (indol e-3-acetic acid) (G affney & Shilling 1995). Although I. cylindrica can produce approximatel y 3000 seeds per plant, spread results primarily from rhizome production (Willard et al. 1990). These 73

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factors make control of I. cylindrica complex. Imperata cylindrica control methods include herbicide use, tillage, hand-pulling, slashing, and use of cover crops (Lum et al. 2005). Revegetating with native pl ants after control of I. cylindrica has been futile and little is known about the potential fo r re-establishing plant communities to resist further invasion of I. cylindrica (MacDonald 2004). Projects to restore heavily disturbed I.cylindrica -dominated sites may be better served by an understanding of the factors that contribute to the success of native species revegetation after invasive species control. Invasive Species and Revegetation Introduction of invasive species rapidly causes a loss of native species, reduces biodiversity, and extirpates populations and communities (Williams 2007); therefore invasive species removal is a critical component of restoration efforts. Revegetation is an importan t, logical subsequent step upon removal of invasive species, but little is known about maximizing revegetation success in a restoration context. Despite this, re vegetating an area r apidly that has been disturbed is important in preventing the introduction of invasive species (Spieles 2005), or the reinvasion of former weeds. Effective revegetation methods following I. cylindrica control have not been established; however several studies have identified potential post I. cylindrica control planting strategies. Plant se lection and plant st ructure are likely important factors to consi der in order to maximize the competitive ability of a revegetated native plant communi ty, but it is unclear if I. cylindrica reinvasion can be constrained by a specific plant community composition. Mesocosm 74

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experiments show decreased I. cylindrica spread and establishment when species such as Andropogon spp. was used in revegetation attempts (Jose 2007). However, a survey of existing native species composition at logged and unlogged sites found that species composition was independent of I. cylindrica spread (Collins 2005). Often, post-planting herbicide treatm ents for invasive species control promote the growth and survival of des irable species (Valenti 2002). Though many studies have addressed controlling I. cylindrica with herbicides prior to planting native species, there is no information on fo llow-up herbicide control for revegetation effort s in initially I. cylindrica -dominated sites. Revegetation efforts only occasionally follow invasive species clearing projects (Galatowitsch & Richards on 2005). Even when native plant communities are not assumed to readily re turn after control and revegetation is needed, limited funds for restoration may prohibit purchase of plant material. The cost of plant material can be part of the reason for high cost of restoration, though a lack of cost-reporting in revegetat ion studies makes this difficult to assess. Plants can be purchased from local native plant nurseries in plug size or larger, or as seeds in t he order of decreasing cost. The primary goal of this research was to establish techniques for the restoration of flatwoods groundcover plant communities in former phosphate mines following I. cylindrica removal. More specifically, this research addresses which plant species and follow-up herbicide treatment provides efficient revegetation and optimal ecosystem function in a restoration context. Costs of 75

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restoration research were closely moni tored so methods can be applicable in a practical context. The final goal wa s to create a management plan for the restored areas to encourage further native species establishment and address potential re-invasion. Materials and Methods Study Site Tenoroc Fish Management Area [TFMA] is the forme r site of the Coronet Phosphate Company that actively mined phosphate during the 1960s and 1970s. After mining operations ceased, the land was abandoned, and the area became heavily invaded by I. cylindrica. Soils at TFMA are overburden (sand and clay mixture removed from the soil surface to uppermost part of the ore moved away from the site). The soil type is 80% sand, 8% silt, and 12% clay which enables the soil to more readily retain water, phosphorus, and potassium than Floridan soils (Richardson et al. 2003) Previous research on I. cylindrica control at the study site found that treatments varied in effect iveness, with application of glyphosate (1.68 kg-ai/ha) resulting in 95% control, and imazapyr (al one or with glyphosate) resulting in less than 50% control (Ketterer 2007). Collect ively, these trea tments resulted in patchy distribution across the experimental study site, consisting of I. cylindrica and other weedy species [e.g. Passiflora incarnata L. (maypop passionflower) Indigofera hirsuta L. (hairy indigo) Eupatorium capillifolium (Lam.) Small (dogfennel), etc.]. Preparation of the study site for this experiment involved application of Round-up (6.18 kg-ai per hectare or 4 qt/A glyphosate), Pasturegard (0.843 kg-ai per hectare tricl opyr+0.281 kg-ai per hectare fluroxypyr 76

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or 2 qt/A fluroxypyr, triclopyr), and addi tion of a non-ionic surfactant (0.25%), followed by mowing A grid map of existing plant species and distribution at the study site was develo ped noting patches of I. cylindrica. From this grid, areas with limited plant cover were identified. In these bare areas, native plant species were installed after mowing in January 2008 when I. cylindrica was dormant. Experimental Design The experiment evaluated the effect of planting regime and follow-up herbicide treatments on establishment of planted native species. Three planting regime treatments were evaluated: no planti ng (control), high structural diversity (HSD: grasses, forbs, and a shrub) and lo w structural diversity (LSD: grasses only). Two follow up herbicide treatments were evaluated: no treatment (control), and glyphosate-treated plots. Treatm ents were applied in a 3x2 randomized complete factorial design with 6 replications for a total of 36 plots. Experimental plots consisted of 12 ft di ameter circles (area = 10.5 m, 113 ft) in which plants were installed. These circular plots we re surrounded by a 2 ft buffer (area= 1.2 m or 12.6 ft) reserved for the herbicide follow up treatment (Figure 3-1). Plants were installed in March 2008 at equal planting densities (42 plants per plot). Species composition and co st of HSD and LSD planting regimes is detailed in Table 3-1. All native plant species were obtained from The Natives, Inc., which were grown less than 20 miles aw ay from the study site in a flatwoods ecosystem and selected based on refe rence ecosystem plant community composition and potential to establish (Nancy Bissett, The Natives, Inc., personal communication, January 18, 2007). 77

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Follow up herbicide treatments were app lied 9 months after planting, in December 2008 (optimal timing for controlling I. cylindrica (Ketterer 2007). Glyphosate (2% solution) was applied to encroaching I. cylindrica at the edge of the plots using a backpack sprayer to spot spray. All efforts were taken to reduce potential impact to the native species installed, but achieve sufficient coverage of I. cylindrica Data Collection Plant volume (m 3 ) was measured at time of installation and at 6, 9, 12, and 18 months after planting. Species survival and species richness of each experimental unit were assessed 6, 9, 12 and 18 months after planting. Percent cover of all unplanted species, including I. cylindrica per plot was evaluated from 0-100% (rounded to the nearest 5%). Seed bank assays were performed prio r to planting, and 3, 6, and 9 months after planting to assess the potential contribution of the seed bank to vegetation dynamics. Seed bank sample s were attained from planted patches, I. cylindrica patches, and in the 2ft (1.17 m) di ameter surrounding planted patches. Density of I. cylindrica, other undesirable species, and desirable species seed was represented by emergence from soil spread in the greenhouse. Statistical Analysis Analysis of variance (Statistical Analysis Software (SAS) version 9.1.3, SAS Institute Inc., 2004) was used to determi ne the effect of planting regime and use of herbicide on plant response (response variables= plant volume and survival rates for each species planted and for overall native species). Means 78

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comparisons were performed using the Least Significant Difference (LSD) procedure. Alpha values were set equal to 0.05. Results Over the study period, survival, growth, and response to treatments were species-specific. All species pl anted persisted thr oughout the 18 month observation period except Ilex glabra, for which no live individuals were observed after the first data collection period (ther efore no figures display information on this species), and Dyschoriste oblongifolia, which did not persist beyond 9 months after planting. Precipitation was higher during time of planting compared with the ten year normal, but generally lower than average during the study period (Figure 3-2). The seedbank assay results (see Appendix A) indicate that no I. cylindrica seed was present in the seed bank during the study period, nor was seed of native species used for revegetation detected. Unplanted native species were, however, found within the seedbank, including: Gnaphalium purpureum Oenothera laciniata Indigofera hirsuta Eupatorium capillifolium and Sida rhombifolia Non-native species detected included: Oxalis spp., Cyperus spp., Aeschynomene spp., and Wahlenbergia marginata Costs incurred throughout the duration of this restoration project totaled less than $1900.00. Total plant cost was approximately $787.04, and herbicide for site preparation and the follow up post-planting application costs were approximately $65.00 and $15.00 respectively Labor costs associated with this restoration project tota led approximately $1000.00. 79

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Plant Survival and Volume Over Time Overall (all native plant species combined) percent survival was not affected by planting treatment or herbicide application. Overall plant volume was greater in high structural diversity (H SD) planting treatment s compared with low structural diversity planting treatments (LSD), particularly at 9 months after planting (Figures 3-3 through 3-11; not e that each figure has a unique y-axis scale, depending on plant volume for the i ndividual species). For all grasses, individual species plant volume was great er in HSD treatments in conjunction with no herbicide applied. An exception was Andropogon brachystachyus, for which volume was similar in both planting treatments (p=0.11). Survival of planted native species dec lined over the 18 month study period to less than 35% for all species except Muhlenbergia capillaris (85% survival) and Aristida beyrichiana (55% survival) No Ilex glabra survived. Overall native plant survival did not differ between plant ing regime (Table 3-2). Survival was greater in untreated plots a fter herbicide application for E. spectabilis (30%), P. anceps (15%), and A. glomeratus (15%) regardless of planting regime. Plant volume increased over time beyond initial measurements for all species before herbicide applic ation, but varied between planting regimes after herbicide application (Table 3-3). Al though plant volume increased for all grasses in the LSD treatment, plant volu me decreased for all grasses in the HSD treatment over time. Plant volume of Panicum anceps Muhlenbergia capillaris Eragrostis spectabilis Aristida beyrichiana and Andropogon brachystachyus was almost 3 times greater in HSD treatm ents than LSD treatments 9 months after planting. Plant volume in HSD treatments, however, declined for most species, 80

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whereas plant volume continually increased over time for all species planted in LSD treatments. No live Dyschoriste oblongifolia individuals were observed beyond 9 months after planting (no furt her data on this species for 12 and 18 MAP). Effects of Herbicide Application on I. cylindrica and Planted Species Imperata cylindrica cover increased rapidly from 0 to 6 months after planting, and then continued to persist at 45-50% cover in control plots (untreated, unplanted plots) but did not exceed 35% in planted plots (Figure 312). Herbicide application decreased I. cylindrica cover to less than 20% immediately following application, but I. cylindrica increased in cover 9 months after application (Figure 3-12). Percent survival and plant volume of planted native species was similar in herbi cide treated and untreated plots before herbicide application, but varied thereafter (Figures 3-3 through 3-11). Overall native species plant volume was lower in HSD plots where I. cylindrica was controlled with the follow up herbicide treatment (p < 0.01). In contrast, individual species plant volumes in treated, LSD plots were greater with the exception of P. anceps Percent survival for P. anceps E. spectabilis, and A. glomeratus was greater than or equal in both planting treatments 12 and 18 months after planting wher e herbicide was not applied. Plant volume and percent survival for Liatris spicata was not affected by herbicide application, but a minor diffe rence in growth was detected both 12 and 18 months after planting. Pityopsis graminifolia volume was also not affected by herbicide application, however, greater survival was detected both 12 and 18 months after planting in treatme nts without herbici de application. 81

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Effects of Structural Di versity on Species Richness and Percent Cover of I. cylindrica Species richness generally increased through 9 months after planting for both planting regimes. After herbicide treatment (12 months after planting) species richness decreased in treated plot s by almost 20%, however, HSD plots consistently had more species than LSD plots. As percent I. cylindrica cover decreased, species richness increased. Unplanted plots contained significantly less (up to 11) species than planted plot s throughout the study period (Figure 312). Overall percent cover of I. cylindrica was greater in experimental units not treated with herbicide regardless of planting regime. Without follow up herbicide treatment HSD pl ots had greater I. cylindrica percent cover compared with LSD plots at the end of the study. After herbicide application, I. cylindrica cover was 18% in treated plots compared to 40% in untreated plots (averaged over planting regime). This reduction in cover was accompanied by an increase in species richness for treated plots. Percent cover of I. cylindrica also decreased slightly (from 40 to 30%) in untreat ed plots, species richness also increased in this situation. Discussion Imperata cylindrica invades in heavily disturbed areas, which by nature are difficult-to-revegetate. Re vegetation efforts in thes e altered environments are further complicated by post-clearing reinvasion by I. cylindrica Results show that planting a species mixt ure of high structural di versity offers the best approach to establishment of native species and defense against further I. 82

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cylindrica reinvasion. Surprisingly, in th is study, follow up herbicide did not promote species richness, and even had some negative impacts on newly establishing natives (especially when planted in high structural diversity plantings). Conversely, there was evidence that fo llow up herbicide promoted greater plant volume in LSD plots where grasses were planted alone. Rates of establishment in this study were clearly impacted by drought conditions. During the critical establishm ent period (0 to 6 months after planting), many species did not achieve significant growth since precipitation was minimal. Adequate water is particularly critical dur ing this phase, and dry conditions cause stress to plants, resulti ng in slow or reduced establishment (Villalobos & de Pelaez 2001; Villagra & Cav agnaro 2006; Sosebee & Wan 1987). Structural Diversity Influenced Planted Species Establishment One of the most interesting observa tions throughout this study is that grasses in HSD plots attained greater volumes than LSD plots. It was hypothesized that grasses would perform better when planted alone (LSD plots) because competition would be limited by other species. One possible explanation for improved grass performanc e in the HSD planting is the nurseplant concept: a member of one species facilitates the growth of another species by ameliorating the stressors of t he local environment (decreasing soil evaporation rates, decreasing micros ite temperatures, and causing less evapotranspiration from plant tissue) (Niering et al. 1963; Raffaele & Veblen 1998). Since the site was relatively dr y during initial plant ing, reducing water losses from the soil was likely critical. As such, using higher structural diversity 83

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planting treatments may have allowed for great er plant volume of grasses as well as greater plant survival of most species planted. Follow-up Herbicide Provided Mixed Results Although it was anticipated that native plant volume would increase in response to I. cylindrica suppression as a result of the follow up herbicide, the outcome of this treatment on native plants was contradictory. For LSD plots, the follow up herbicide application result ed in higher native plant volumes, presumably a result of the reduction in I. cylindrica provided by the selectivelyapplied herbicide. However in HSD plot s, plant volumes were greater where herbicide was not applied. A possible reason for decreased plant volumes in response to the herbicide application in HS D plots is that during application to I. cylindrica some solution may have drifted onto the installed native plants. It could be that native species were more susceptible to these non-target herbicide effects in HSD plantings, where increas ed structure provided greater surface area to intercept drifting herbicide. Survival, however, was generally gr eater in plots where herbicide was applied to treat surrounding I. cylindrica regardless of planting regime where herbicide drift may have caused plant stunti ng, but not mortality. Control of the invasive generally allows for greater spread and survival of desirable species (Shilling et al. 1997; Miller 2000). Post-planting Community Dynamics There was also an abundance of undesirable forbs which recolonized throughout the study. Per haps planting grasses initially, controlling for undesirable forbs and I. cylindrica then establishing native, desirable forbs after 84

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control is complete would increase the likelihood of restoring certain ecosystem functions and values. It is interesting to note that species richness was always greater in planted plots regardless of herbicide application. After herbicide application, however, species richness initially declined in all planting treatments (when measured during winter months at 12 months after planting), then increased 18 months after planting. Unplanted plots, however, never reached a richness quantity greater than six. Possibly because spec ies were planted at consistent densities, species richness was not as variable as expected since there was a lack of interspecific competition where members of a different species vie for the same environmental resources such as water and soil nutrients (Budelsky & Galatowitsch 2000). Another possible reason for the lack of increase in species richness could be the minimal vegetati on surrounding the site (monotypic stands of Sporobolis indicus (smutgrass)) was not diverse. Relative Costs of Treatments Restoration project costs vary fr om $2000 for less than 10 hectares to greater than $51,000 per hectare for restor ation where exotic invasive species removal is part of the restoration goal (Henri et al. 2004; Macmillan et al. 1998; Rashford & Adams 2007). In comparison, t he cost of this rest oration project was at the lesser end of other restoration projects. Conclusions: Implications for Practice Initial I. cylindrica control efforts should result in relatively bare ground. In addition to reinvading I. cylindrica ruderal weedy species may compete with any revegetation efforts. Ther efore, identifying undesirable recolonizing species prior 85

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86 to designing a revegetation plan has some benefit. For example, if recolonizing undesirable species are mainly forbs, plant ing grasses only at this initial stage would afford the use of a forb-specific herbicide that will not threaten planted grass establishment. Similarly, if gra sses are primarily problematic, planting forbs and shrubs only, and using a gra ss specific herbicide would preserve planted native species and control undesirable grasses, including I. cylindrica. Note that a two-stage planting effort may be compatible with this approach; e.g. 1) plant native grasses, 2) selectively control undesirable forbs, and 3) plant native forbs. Because undesirable specie s may persist past an initial selective control herbicide application, plan for potent ially multiple selective control efforts (these may take a year or more) prior to planting native species. Selecting appropriate species for re vegetation efforts will increase chances of establishment. Plant species with a high likelihood of establishment and ability to survive harsh environmental extremes, such as Muhlenbergia capillaris. Aristida stricta and Liatris spicata may also be suitable for heavily-degraded and drought-prone areas. Initial invasive species reduction and native species establishment may be resource intensive. However, after years of native species survival and reproduction, along with follow-up control of undesirable and invasive species via chemical application, management needs may eventually be reduced.

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Table 3-1. List of species, quantity, total number of plants, cost per plant, and overall cost for species used for revegetation. Quantity Species Growth form LSD* HSD** Total number of plants Cost per plant ($) Amount ($) Andropogon brachystachyus Chapm. Grass 7 3 120 0.48 56.60 Eragrostis spectabilis (Pursh) Steud. Grass 7 3 120 0.48 56.60 Aristida beyrichiana Trin. & Rupr. Grass 7 4 132 0.51 67.32 Panicum anceps Michx. Grass 7 3 120 0.48 56.60 Andropogon virginicus L. Grass 7 3 120 0.48 56.60 Muhlenbergia capillaris (Lam.) Trin. Grass 7 4 132 0.51 67.32 Dyschoriste oblongifolia (Michx.) Kuntzel Forb 5 60 2.25 135.00 Liatris spicata (L.) Willd Forb 6 72 1.25 90.00 Pityopsis graminifolia (Michx.) Nutt. Forb 8 96 1.25 120.00 Ilex glabra (L.) A. Gray Shrub 3 36 2.25 81.00 Total 42 42 787.04 LSD = low structural diversity ** HSD = high structural diversity 87

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Table 3-2. Analysis of variance for the effects of planting r egime (Reg.), herbicide application (Herb.), and 0, 6, 9, 12, and 18 months after initial plantin g (MAP) on percent survival of all surviving species. Grasses Forbs* Overall survival A. brachystachyus Aristida Eragrostis Muhlenbergia Panicum A. glomeratus Pityopsis Liatris Source F P F P F P F P F P F P F P F P F P Reg. 0.39 0.53 0.23 0.63 0.28 0.59 1.76 0.18 0.08 0.77 1.03 0.31 0.31 0.57 Herb. 3.38 0.06 0.00 0.95 2.15 0.14 8.11 0.01 2.48 0.11 4.70 0.03 3.91 0.04 3.09 0.08 0.32 0.57 Reg*herb. 3.63 0.06 0.50 0.48 0.45 0.50 0.03 0.86 4.54 0.03 0.44 0.50 0.94 0.33 MAP 14.58 0.01 7.46 0.01 0.00 1.00 0.40 0.52 0.06 0.80 31.62 <0.01 0.53 0.46 3.12 0.07 1.76 0.18 Reg*MAP 0.00 0.98 0.10 0.75 0.06 0.79 0.91 0.34 0.44 0.50 0.00 0.96 0.23 0.62 Herb*MAP 0.00 0.95 1.10 0.42 0.00 1.00 0.10 0.75 1.26 0.26 0.45 0.50 0.20 0.65 1.22 0.27 0.32 0.57 *Results are not shown for I. glabra or D. oblongifolia as these species did not survive past 9 months after planting. 88

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89 Table 3-3. Analysis of variance for the effects of planting r egime (Reg), herbicide applicati on (Herb), and 0, 6, 9, 12, and 18 months after initial planting (MAP) on total plant volume and species richness of all surviving species. Grasses Forbs* Overall volume Species richness A. brachystachyus Aristida Eragrostis Muhlenbergia Panicum A. glomeratus Pityopsis Liatris Source F P F P F P F P F P F P F P F P F P F P Reg. 226.73 <0.01 950.06 <0.01 2.65 0.11 31.41 <0.01 12.1 0.01 268.2 <0.01 28.33 <0.01 3.89 0.05 Herb. 3.35 0.06 42.74 <0.01 0.29 0.59 0.74 0.39 0.76 0.38 1.58 0.21 1.4 0.24 0 0.98 0.02 0.88 2.7 0.11 Reg*herb. 30.75 <0.01 0.25 0.77 7.0 0.01 9.26 0.01 4.58 0.04 4.15 0.04 0 0.97 9.25 0.01 MAP 68.99 <0.01 9.45 <0.01 21.03 <0.01 30.7 <0.01 3.59 0.06 0.02 0.88 56.76 <0.01 22.55 <0.01 0.07 0.79 24.94 <0.01 Reg*MAP 224.78 <0.01 5.47 <0.01 4.56 0.04 29.0 <0.01 4.43 0.04 266.6 <0.01 1.06 0.31 6.08 0.02 Herb*MAP 6.36 0.01 6.41 <0.01 6.0 0.02 1.12 0.29 0.6 0.44 1.63 0.20 0.82 0.37 3.36 0.07 0.18 0.68 0.65 0.43 *Results are not shown for I. glabra or D. oblongifolia as these species did not survive past 9 months after planting.

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90 Figure 3-1. Schematic of a circular study plot with 12 ft diameter planting area and 2 ft buffer reserved for the follow up herbicide application. Half of all experimental units were assigned an herbicide treatment. 12 ft diameter planting area I. cylindrica patch (herbicide applied only to I. cylindrica invading the 2 ft buffer) 2 ft buffer reserved for herbicide treatment

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91 Figure 3-2. Precipitation patterns durin g the study period (March 2008 (initial ti me of planting and 12 months after planting)-September 2009 (6 months after planting and 18 months after planting)) and ten year average.

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92 Figure 3-3. Andropogon brachystachyus the effects of planting regime and herbicide application on plant volume and survival. Mean of 6 replicatio ns followed by standard error.

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93 Figure 3-4. Andropogon glomeratus the effects of planting regime and herbicide application on plant volume and survival. Mean of 6 replicatio ns followed by standard error.

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94 Figure 3-5. Aristida stricta the effects of planting regime and herbicide app lication on plant volume and survival. Mean of 6 replications followed by standard error.

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95 Figure 3-6. Dyschoriste oblongifolia the effects of herbicide on plant volume and survival. Mean of 6 replicat ions followed by standard error.

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96 Figure 3-7. Eragrostis spectabilis the effects of planting regime and herbicide application on plant volume and survival. Mean of 6 replications fo llowed by standard error.

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97 Figure 3-8. Liatris spicata the effects of herbicide application on plant volume and survival. Mean of 6 replicati ons followed by standard error.

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Figure 3-9. Muhlenbergia capillaris the effects of planting regime and herbicide application on plant volume and survival. Mean of 6 replicat ions followed by standard error. 98

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99 Figure 3-10. Panicum anceps the effects of planting r egime and herbicide application on plant volume and survival. Mean of 6 replications followed by standard error.

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100 Figure 3-11. Pityopsis graminifolia the effects of herbicide application on plant volume and survival. Mean of 6 replicat ions followed by standard error.

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101 Figure 3-12. Effects of planting regime and herbicide application on species ri chness and percent cover of I. cylindrica Mean of 6 replications followed by standard error.

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CHAPTER 4 CONCLUSIONS Floridas landscape consists of unique and highly valued natural conservation areas including: forests, flatwoods, prai ries, swamps, and marshes. Rapid population growth makes Florida susceptible to land di sturbances. Opportunist ic plant species, such as Imperata cylindrica (cogongrass), Salix caroliniana (coastalplain willow) and Typha spp. (cattail), have become problematic by displacing Floridas native plant communities. Removal of species that prec lude native plant communities is important to conserving Floridas unique ecosystems. Though rarely attempted in practice, revegetation after invasive species remova l assists in restorat ion of native plant communities. Little is known about revegetation attempts after invasive species removal. Planting density, planting el evation, propagule size, and herbi cide application may play an important role in successfully revegetat ing a disturbed ecosystem. The research previously stated shows that planting at sparse densities increases the likelihood of survival for Juncus polycephalos Pluchea rosea Cyperus haspan Eleocharis atropurpurea, and Fuirena breviseta most likely because competition is reduced. Planting elevation was another parameter investigated by th is research. We note that several species preferences emerged, even for the small difference in hydrologic condition that resulted from the elevation differential test ed in this study. Larger propagule size plants establish more eas ily, and may buffer harsh environmental conditions for newly establishing species. It is well known that for heavily invaded si tes, broadscale herbicide treatment for initial removal of invasive species in creases the likelihood of native species 102

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establishment. Active revegetation by planti ng native species following invasive species removal is likely critical and, as we found in this study, also deters I. cylindrica from further spreading. High structural dive rsity (HSD) plantings are recommended as greater volumes and survival rates were obser ved for species planted in this regime. Follow-up herbicide application reduced I. cylindrica cover by 30%, but had no effect on native species performance at the end of the study period in HS D planting regimes, possibly due to non-target effe cts of the herbicide application on native species in the HSD plantings. To reduce non-target effects of the herbicide, extr eme care is required to avoid planted species during application. Therefore, it is recommended to carefully decide whether follow-up herbicide treatments should be applied. This research also suggests a two-stage planting effort may be a more effective approach than a single planting event. For instance, 1) plant native grasses, 2) selectively control undesirable forbs (planted grasses will be unaffected), and 3) plant again with native forbs. Because undesirable species may persist past an initial selective control herbicide application, plan for potentially multiple select ive control efforts (these may take a year or more) prior to planting subsequent native species. Initial removal of invasive species is one of the first steps in successfully restoring a native plant communi ty. After removal, actively revegetating native plant communities, taking into account species preferences for envir onmental influences, should be a priority. Followup herbicide treatments should be applied appropriately. On-going monitoring to track plant community development will allo w identification of further interventions necessary to restore these plant communities. 103

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APPENDIX A Table A-1. Number of plant s per species present in s eedbank at TFMA 0, 3, 6, and 9 months after planting in the I. cylindrica patch, edge of pl anting area, and inside the planting area. Species In planting area Edge of planting area In I. cylindrica patch 0 months after planting Gnaphalium purpureum 79 24 29 Oenothera laciniata 2 0 1 Oxalis spp. 2 4 4 Cyperus spp. 15 7 14 3 months after planting Gnaphalium purpureum 0 0 0 Oenothera laciniata 0 0 1 Oxalis spp. 5 0 0 Cyperus spp. 2 25 4 Indigofera hirsuta 50 22 27 Eupatorium capillifolium 1 1 1 Aeschynomene spp. 0 1 1 6 months after planting Gnaphalium purpureum 181 138 157 Oenothera laciniata 0 0 0 Oxalis spp. 0 0 0 Cyperus spp. 0 0 1 Indigofera hirsuta 6 0 0 Eupatorium capillifolium 0 0 1 Aeschynomene spp. 2 0 0 Sida rhombifolia 2 6 1 Wahlenbergia marginata 74 97 62 9 months after planting Gnaphalium purpureum 135 134 360 Oenothera laciniata 0 0 0 Oxalis spp. 3 4 3 Cyperus spp. 2 5 3 Indigofera hirsuta 0 0 0 Eupatorium capillifolium 0 0 0 Aeschynomene spp. 0 0 0 Sida rhombifolia 0 0 0 Wahlenbergia marginata 133 239 93 104

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LIST OF REFERENCES Adams, C. R., K. A. Villazon, M. Kane, and L. Richardson. 2009. Historic pond restoration in the Flori da Panther National Wildlife Refuge. Florida Fish and Wildlife Cooperative Unit Progress Report. 39 pp. Aronson, M. F. J. and S. Galatowitsch. 2008. Long-term vegetation development of restored prairie pothole wetlands. Wetlands 28: 883-895. Ayeni, A.O. 1985. Observations on the v egetative growth patterns of speargrass [ Imperata cylindrica (L.) Beauv.]. Agriculture, Ecosystems & Environment 13: 301307. Ayeni, A.O. and W.B. Duke. 1985. The infl uence of rhizome features on subsequent regenerative capacity in speargrass ( Imperata cylindrica (L.) Beauv.). Agriculture, Ecosystems & Environment 13: 309-317. Baer, S. G., J. M. Blair, S. L. Colli ns, and A. K. Knapp. 2004. Plant community responses to resource availability and heterogeneity during restoration. Oecologia 139: 617-629. Bakker, J. P., J. A. Elzinga, and Y. de Vries. 2002. Effects of long-term cutting in a grassland system: perspectives for restor ation of plant communities on nutrientpoor soils. Applied Vegetation Science 5: 107-120. Blumenthal, D. M., N. R. Jordan, and E. L. Svenson. 2005. Effects of prairie restoration on weed invasions. Agriculture, Ecosystems and Environment 107: 221-230. Bos, A. and M. M. van Kat wijk. 2007. Planting density, hydrodynamic exposure and mussel beds affect survival of transplanted intertidal eelgrass Marine Ecology Progress Series 336: 21-129. Brook, R.M. 1989 Review of literature on Imperata cylindrica (L.) Raeuschel with particular reference to South East Asia. Tropical Pest Management 35: 2-25. Bryson, C.T. and R. Ca rter. 1993. Cogongrass, Imperata cylindrica in the United States. Weed Technology 7: 1005-1009. Budelsky, R. A. and S. M. Ga latowitsch. 2000. Effects of water regime and competition on the establishment of a native sedge in restored wetlands. Journal of Applied Ecology 37: 971-985. Buisson, E., K. D. Holl, S. Anderson, E. Co rcket, G. F. Hayes, F. Torre, A. Peteers, and T. Dutoit. 2006. Effect of seed source topsoil removal, and plant neighbor removal on restoring California coas tal prairies. Restoration Ecology 14: 569-577. 105

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BIOGRAPHICAL SKETCH Kathryn was born and raised in Homestead, Florida and attended the University of Florida (UF). Her resear ch career began at UF where she worked in a plant tissue culture and micropropagation lab studying the effects of plant growth regulators and basal salts on i nducing root and shoot organogensis in the aquatic plant Aponogeton madagascariensis under the supervision of Dr. Michael Kane. Although she loved laboratory rese arch, she decided field research was more fitting since her greatest passions exist in the outdoor environment. Kathryn graduated from UF in 2007 with a ma jor in Interdisciplinary Studies with a concentration in Environmental Horticul ture Operations. She joined the Plant Restoration, Conservation, and Propagation Biotec hnology Program in the Environmental Horticulture Department at UF in February 2006. She was fortunate enough to venture in wetland and upland restoration projects. In her spare time Kathryn enjoys hunting, fishing, photography, crocheting, playing various instruments, and writing biographies in the third person. 113