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Schmidt, Anne Candace.
A vascular plant inventory and description of the twelve plant community types found in the University of South Florida ecological research area, Hillsborough County, Florida
h [electronic resource] /
by Anne Candace Schmidt.
[Tampa, Fla.] :
b University of South Florida,
Thesis (M.S.)--University of South Florida, 2005.
Includes bibliographical references.
Text (Electronic thesis) in PDF format.
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ABSTRACT: The University of South Florida Ecological Research Area (USF Eco Area), located in west central Hillsborough County, is an approximately 306 hectare (756 acre) natural area on the Hillsborough River composed of twelve plant communities. While surrounded on three sides by urbanization, the USF Eco Area makes up the western most section of an extended natural corridor that runs approximately 88 kilometers (55 miles) east and north along the Hillsborough River. An inventory of the vascular flora and the associated ecological communities was developed to better assess the USF Eco Area for educational and research purposes as well as enhance informed decisions when evaluating its status for conservation and management purposes. The study, conducted from June 2001 through August 2005, documented 404 vascular plant taxa in 251 genera and 102 families.
Adviser: Richard P. Wunderlin, Ph.D.
Co-adviser: Frederick B. Essig, Ph.D.
Natural plant communities.
t USF Electronic Theses and Dissertations.
A Vascular Plant Inventory and Description of th e Twelve Plant Community Types Found in the University of South Florida Ecological Research Area, Hillsborough County, Florida by Anne Candace Schmidt A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science Department of Biology College of Arts and Sciences University of South Florida Co-Major Professor: Richard P. Wunderlin, Ph.D. Co-Major Professor: Frederick B. Essig, Ph.D. Gordon A. Fox, Ph.D. Date of Approval: July 29, 2005 Keywords: floristic survey, natural plant communities, conservation, management, anthropogenic perturbations Copyright 2005, Anne Candace Schmidt
i Table of Contents List of Tables..................................................................................................................................iii List of Figures.................................................................................................................................iv Abstract...........................................................................................................................................vi Introduction................................................................................................................... ...................1 Site Overview.................................................................................................................. ................2 Physical Location.................................................................................................. ...............2 Early Inhabitants..................................................................................................................4 Historical Land Uses and History of Land Acquisition.......................................................6 Climate............................................................................................................ .....................8 Geology............................................................................................................ ....................9 Topography, Hydrology, and Soils................................................................................... ...9 Methods........................................................................................................................ .................12 Field Collections.................................................................................................. ..............12 Delineation and Ch aracterization of Plant Communities...................................................12 Data Organization.................................................................................................. ............14 Results and Discussion......................................................................................................... .........15 Floristics......................................................................................................... ....................15 Plant Communities.................................................................................................. ...........18 Riverine Community.................................................................................... .........22 Blackwater Stream........................................................................ ...........22 Palustrine Communities................................................................................ ........28 Floodplain Swamp......................................................................... ..........28
ii Floodplain Forest........................................................................ .............33 Floodplain Marsh......................................................................... ............36 Hydric Hammock.....................................................................................39 Seepage Slope............................................................................ ..............44 Wet Flatwoods............................................................................ .............50 Terrestrial Communities............................................................................... ........55 Mesic Flatwoods.......................................................................... ............56 Scrubby Flatwoods........................................................................ ...........62 Sandhill................................................................................. ...................66 Xeric Hammock............................................................................ ...........74 Ruderal/Developed........................................................................ ...........81 Annotated List of the Vascular Flora........................................................................................... ..84 Pteridoph ytes (Ferns and Fern Allies).............................................................................. .85 Gymnosperms........................................................................................................ ............86 Angiosperms (Monocotyledons)....................................................................................... .86 Angiosperms (Dicotyledons)......................................................................................... ....93 Conclusion..................................................................................................................... ..............108 Literature Cited............................................................................................................... .............109 Appendices..................................................................................................................... ..............112 Appendix A: Summary of Research Activities on the Ecological Research Area..........113 Appendix B: Dates of controlled burns at the USF eco area .........................................118
iii List of Tables Table 1. University of South Florida Ecol ogical Research Area floristic synopsis......................15 Table 2. Vascular plant taxa endemic to Florid a occurring in the University of South Florida Ecological Research Area........................................................................................ .......16 Table 3. Florida Exotic Pest Plant Council listed invasive vascular plant taxa found in the University of South Florida Ecological Research Area..................................................17 Table 4. New records of vascular plant taxa for Hillsborough County found in the University of South Florida Ecological Research Area....................................................................17 Table 5. University of South Florida Ecological Research Area vascular plant taxa listed as endangered, threatened, or commercially exploited by the Florida Department of Agriculture and Consumer Services...........................................................................1 8 Table 6. Areas of the twelve plant communities found in the University of South Florida Ecological Research Area........................................................................................ .......19
iv List of Figures Figure 1. Map of Florida showing the location of the University of South Florida Ecological Research Ar ea (USF Eco Area) in Hillsborough County................................................2 Figure 2. A color infrared aerial of the University of South Florida Ecological Research Area....3 Figure 3. Old pilings are the only signs left from the 880 foot bridge that had provided access to Buck Island across the swamp during the Works Progress Administration 1937 archaeological survey and excavations of Buck Island....................................................5 Figure 4. 1938 USDA/SCS Hillsborough Coun ty Soils Survey aerial photograph........................6 Figure 5. National Wetland Inventory map of the University of South Florida Ecological Research Area showing the NWI wetland type classification.......................................10 Figure 6. Soil type classification in the University of South Florida Ecological Research Area from the 1989 USDA/SCS Hillsborough County Soil Survey......................................11 Figure 7. Historic and recent aerial photographs of the University of South Florida Ecological Research Area.................................................................................................. ..............13 Figure 8. The University of South Florida Ecological Research Area plant communities...........20 Figure 9. Percent areas of the thirteen plant communities found in the University of South Florida Ecological Research Area.......................................................................21 Figure 10. The blackwater stream plant community type in the University of South Florida Ecological Research Area............................................................................. ...23 Figure 11. The floodplain swamp is the dominant plant community in the University of South Florida Ecological Research Area............................................................................. ...29 Figure 12. Floodplain forest in the northwest corner of the University of South Florida Ecological Research Area..................................................................................... .......34
v Figure 13. Floodplain marsh in the University of South Florida Ecological Research Area is found west of the Hillsborough River.......................................................................... .38 Figure 14. University of South Florida Ec ological Research Area hydric hammock....................40 Figure 15. The seepage slope is one of the smalle st plant communities found in the University of South Florida Ecological Research Area......................................................................46 Figure 16. Wet flatwoods in the University of South Florida Ecological Research Area.............52 Figure 17. University of South Florida Ecological Research Area mesic flatwoods.....................57 Figure 18. Scrubby flatwoods in the University of South Florida Ecological Research Area.......62 Figure 19. University of South Florida Ecol ogical Research Area sandhill plant community......67 Figure 20. Experimental burn plots in the University of South Florida Ecological Research Area.......................................................................................................... .....................68 Figure 21. Areas of xeric hammock plant commun ity in the University of South Florida Ecological Research Area...................................................................................... .......75 Figure 22. Ruderal/developed plant community in the University of South Florida Ecological R esearch Area................................................................................................. ..............82
vi A Vascular Plant Inventory and Description of th e Twelve Plant Community Types Found in the University of South Florida Ecological Research Area, Hillsborough County, Florida Anne Candace Schmidt ABSTRACT The University of South Florida Ecological Research Area (USF Eco Area), located in west central Hillsborough County, is an approximately 306 hectare (756 acre) natural area on the Hillsborough River composed of twelve plant co mmunities. While surrounded on three sides by urbanization, the USF Eco Area makes up the western most section of an extended natural corridor that runs approximately 88 kilometers (55 miles) east and north along the Hillsborough River. An inventory of the vascular flor a and the associated ecological communities was developed to better assess the USF Eco Area for educational and research purposes as well as enhance informed decisions when evaluating its status for conservation and management purposes. The study, conducted from June 2001 through August 2005, documented 404 vascular plant taxa in 251 genera and 102 families. Three hundred and seventy-eight taxa (94%) are native to Florida of which 13 are endemic; ni ne are listed as endangered, threatened, or commercially exploited; four are first time re corded occurrences for Hillsborough County; and ten taxa are listed as Florida Exotic Pest Plant C ouncils Category I or II invasive species. Eleven natural plant communities and one ruderal/dev eloped plant community were documented, mapped and characterized by their unique vege tative, topographic, soil, and hydrological components based on qualitative field observations The blackwater stream, floodplain swamp, floodplain forest, floodplain marsh, hydric hammock, seepage slope, and wet flatwoods are wetland plant communities that cover 65% of the USF Eco Area. Upland plant communities,
vii covering the remaining 35%, are mesic flatw oods, scrubby flatwoods, sandhill, xeric hammock, and ruderal/developed.
1 INTRODUCTION The University of South Florida (USF) owns a natural area on the Hillsborough River, just north of the Tampa campus, referred to as the University of South Florida Ecological Research Area (USF Eco Area). It is essentially an urban forest surrounded on three sides by intensive development. Throughout the years, the USF Eco Area has been a valuable resource for education and research in the natural and envi ronmental sciences as well as anthropological studies. However, a thorough study has not been done documenting the vegetative, geological, and hydrological structure and characteristics of the area in order to better assess the USF Eco Area for educational and research purposes as well as enhance informed decisions when evaluating its status for conservation and management Therefore, the objective of this study is to document the flora and associated ecological co mmunities, as they presently occur in the USF Eco Area, incorporating general information about the areas geological and hydrological characteristics. The floristics and the 12 natural plant communities documented and mapped in the present study revealed that the USF Eco Area is a biologi cally rich and diverse natural area despite being somewhat compromised by surrounding anthropogenic perturbations and its small size. The diversity of integrated ecosystems in the USF Eco Area provides USF with an excellent resource for both education and research, much needed in this day and age of habitat loss and fragmentation and the accelerated extinction of species threatening the very essence of biodiversity.
SITE OVERVIEW Physical Location The USF Eco Area is located near the west coast of central Florida, within the city of Tampa, Hillsborough County, Township 28 S, Range 19 E, Sections 2, 3, and 4 (Figure 1). USF ECO AREA Tallahassee Figure 1. Map of Florida showing the location of the University of South Florida Ecological Research Area (USF Eco Area) in Hillsborough County. (Modified from Florida Center for Instructional Technology 2002 and Mapquest 2005). 2
USF Golf CourseBuck IslandFletcher AvenueE-W Eco Area RoadOld Logging RoadWest GateEast GateRiverfront ParkLettuce Lake Park56thStreetUSF CampusBuck HammockTampa PalmsTampa Palms Cypress CreekCypress CreekFletcher Avenue The property comprises approximately 306 hectares (ha) or 756 acres (a) bounded by the Tampa Palms development to the north, the Hillsborough River to the east, Fletcher Avenue to the south, and the University of South Florida Golf Course to the west (Figure 2). 3 B ruce B, DownsN-S Eco Area Road NESWCypress CreekBurn PlotsHillsborough River Figure 2. A color infrared aerial of the University of South Florida Ecological Research Area. The property boundary of the USF Eco Area is outlined in green. Approximate course of Cypress Creek flowing through the USF Eco Area is represented by the dotted blue line. (Modified from SWFWMD GIS Division 1999 color infrared aerial photograph). Over half of the USF Eco Area is composed of floodplain wetlands associated with Cypress Creek and the Hillsborough River. Cypress Creek flows through the area from west to east until it empties into the Hillsborough River within the USF Eco Area boundaries. The rest of the USF Eco Area is composed of natural and developed uplands. The natural uplands are in the south central and southeastern sections of the area and dip north into the floodplain swamp (Figure 2).
4 The developed uplands are composed of the USF Golf Course, along the entire western edge, and Riverfront Park, on the southeast corner (Figure 2). Despite the encroaching intensive devel opment to the north, south, and west, the USF Eco Area has remained a natural area and has become the western most section to an extended natural corridor that runs approximately 88 kilometers (55 miles) east and north along the Hillsborough River that includes conservation lands owned by the State of Florida (Southwest Florida Water Management District, Hillsborough River State Park, Green Swamp) and Hillsborough County (Lettuce Lake Park). A recent report by the Florida Natural Areas Inventory (FNAI) categorized the entire USF Eco Area as a Potential Habitat for Rare Species (FNAI/Abbey 2004). FNAI lists several recorded occurrences for the USF Eco Area of rare, endange red, and threatened globally, federally, and state listed plant and anim al species and one natural community. Early Inhabitants Humans have inhabited the Hillsborough Ri ver watershed for at least 10,000 years. Evidence of human occupation in the USF Eco Area was first revealed in 1937 through archaeological investigations conducted by J. Clarence Simp son under the auspices of the Works Progress Administration (Bullen 1952; Collins 2005; Eyles et al. 2001). Simpson and his crew found evidence of Indian occupation on Buck Island, lo cated in the middle of the floodplain swamp, east of the USF Golf Course. Pottery, tools, sherds, two gold discs, and beads as well as skeletal material disclosed signs of village life and a burial area or mound dating from the Weedon Island (ca.700,000 A.D.) to Safety Harbor Periods (ca.1,000,500 A.D). Some of the excavated materials date as far back as the Archaic Period (ca. 8,0003,200 B.P.). Evidence of interactions between the Spanish, who had been recorded to have been in th e area during the Safety Harbor Period, and the indigenous people of Buck Island were disclosed in some of the beads found in with the Safety Harbor excavations. Some of th e beads had been made from European materials
that had been reworked into traditional designs of the period. Several pilings still remain from the 880 foot bridge Simpson and his crew had to construct for access to Buck Island through the swamp (Figure 3). The bridge had also included 526 feet of earth fill. Figure 3. Old pilings are the only signs left from the 880 foot bridge that had provided access to Buck Island across the swamp during the Works Progress Administration 1937 archeological survey and excavations of Buck Island. (Photograph courtesy of Dan Duerr). Six archaeological sites in the USF Eco Area have been investigated by the Department of Anthropology at USF. Evidence from the sites revealed habitation in the area dating from the Archaic Period to Middle Woodland times (ca. 1,500 B.P) (Collins 2005; Eyles et al. 2001). 5
Historical Land Uses and History of Acquisition Information is scarce on the historical land uses of the USF Eco Area hence it has primarily been gleaned from old aerial photographs dating as far back as 1938, local knowledge, and observations in the field during the present study where, in passing, evidence of past habitation and land uses had been noted. As predominantly comprised of swamp and wetlands, the USF Eco Area would have been, for the most part, impenetrable for any uses other than hunting and fishing. A 1938 USDA/SCS Hillsborough County Soil Survey aerial photograph reveals that the uplands had been used for pasture (Figure 4). Figure 4. 1938 USDA/SCS Hillsborough County Soil Survey aerial photograph (courtesy of the Environmental Protection Commission of Hillsborough County). 6
7 There also appears to have been a home site ju st northeast of the west gate going into the USF Eco Area. Field observations have somewhat back ed up the placement of the home site in having noted an unusual presence, for the area, of several loblolly pines ( Pinus taeda ) and one, fairly large red cedar ( Juniperus virginiana ). Logging and turpentine operations also a ppear to have taken place on the site. The northsouth dirt road that goes through the USF Eco Area, along the upland ridge that dips north into the floodplain swamp, is on the 1938 aerial photogra ph. Local knowledge says that this had been an old logging road that had been, prior to 19 38, deeply excavated th rough the upland for access to cypress trees in the floodplain swamp to the north. Cat faces, observed on several long leaf pines ( Pinus palustris ) throughout the site, revealed signs of past turpentine operations. On Dec. 18, 1956 the Board of Education finally agreed on the current site for the then new University of South Florida (Leland Hawes, Ta mpa Tribune, Oct. 30, 1986). Along with this decision, a Mr. Stanton Sanson generously donate d an approximately 700 more acres, north of Fletcher Avenue, to the new university. Mr. Sansons donation provided the new USF with open land that had frontage on the Hillsborough River. By 1960, classes were meeting in the first five buildings on the main campus; by 1961, planning for Riverfront Park had been approved; and by 1966, construction of the USF Golf Course was well under way (Leland Hawes, Tampa Tribune, Oct. 30, 1986; Personal Communication: Florid a Studies Center; USF Recreation Department). The USF Eco Area has primarily been used as a resource for education and research in the natural and environmental sciences as well as the above mentioned anthropological studies (Collins unpublished; Eyles et al. 2002). Record s of ecological research conducted in the USF Eco Area date back to 1971 (Appendix A). Prior botanical investigation in the USF Eco Area was conducted by Lakela, Hansen, Rich ardson, Williamson, and Wunderlin. There are discrepancies as to where the ex act placement of the northern boundary is for the USF Eco Area. Between 1956 and today the northern boundary had been changed.
8 Investigations have yet to produce results as to when and why the boundary had been changed. A title search is currently being conducted to solve th e mystery. The northern boundary of the USF Eco Area, used in the present study, is the one currently on record with Hillsborough County. Climate In the Holdridge Life Zone System that is based on mean annual temperature and precipitation gradients throughout Florida, Hillsborough County falls in the bioclimatic transition zone between the warm temperate moist forest to the north and the subtropical moist forest to the south (Meyers 2000). The USF Eco Area experiences the typical cyclical subtropical climate of a humid, rainy, and particularly warm period, from June through September, and a dry, mild, but relatively cool period from October through May, w ith April, May, October, and November being the driest months of the year (Chen and Gerb er 1990; Meyers 2000; Winsberg 2003). Summers include a high frequency of thunderstorms and li ghtning, tropical storms, and periodic tornadoes and hurricanes. The cool and dry winters are often punctuated with cold and warm fronts preceded by winds and precipitation that bri ng brief periods of below or above average temperatures, respectively. The prevailing winds for the area are predominantly east northeast at an average of eight miles per hour annually, with more of a westerly flow from July through September. In January, the temperature average ranges from 10.4 o C (50.8 o F) to 21.4 o C (70.5 o F) and in August, from 23.7 o C (74.6 o F) to 32.4 o C (90.3 o F) (SERCC 2005). During the winter, temperatures can infrequently drop to or just below freezing for short periods of ti me. The rainy season, extending from June through September, typically has an average precipitation of 72.11 cm (28.39 in) (SERCC 2005). Annually, the average precipitation is 120.9 cm (47.58 in), with August typically receiving the most precipitation at an average of 20.16 cm (7.94 in) and November receiving the least at 4.0 cm (1.6 in) (SERCC 2005).
9 Geology The USF Eco Area is associated with the Post Oligocene epoch Ocala Uplift area where it lies on the Tampa Member of the Hawthorn Group Formation, dating from the Upper Oligocene to Miocene epochs of the Tertiary period (5 MYBP) (Brown et al. 1990; Meyers 2000; Scott et al. 2001; Scott 2001; Webb 1990). In the Ocal a Uplift area, clastic and marine carbonate sediments are typically thin over the lithologi es of the Hawthorn formation that include limestone, dolostone, sand, and clay, with some exceptions where sediments can be 100 meters thick with a dense layer of impermeable clay between overlying sands and underlying limestone. Topography, Hydrology, and Soils The USF Eco Area is essentially in the eco tone of two physiographic districts that are included in the Gulf Coastal Lowlands Region of the Gulf Coastal Plain Physiographic Province (Brown et al. 1990; Meyers 2000; Webb 1990). It is located at the southern end of the Ocala Uplift Physiographic District and on the cusp of the northern end of the Southwestern Flatwoods Physiographic District. Both districts reflect the characteristic topography of the Gulf Coastal Lowlands Physiographic Region that includes sweeping expanses of poorly drained, low, flatlands and swampy depressions punctuated by ve ry dry, sandy hills and ridges that were once Plio-Pleistocence shorelines, sand dunes and ridges. The Ocala Uplift District is characterized by a heterogeneous landscape of hills and low, primarily karst, flats with limestone at or near the surface that, when covered, is thinly overlain with varied sediment types (Brown et al. 1990; Meyers 2000; Webb 1990). Karst plains, pine flatwoods, sandhills, mixed hardwood forests, swamps, and streams typically occur in the district. The Southwestern Flatwoods District di ffers from the Ocala Uplift in that it has less heterogeneity in the topography with predominat ely low flat terrain and fewer hills and ridges (Brown et al. 1990; Meyers 2000; Webb 1990). Sediments over the bedrock are predominantly
sand with clay substrata, limestone, and organic materials. Pine flatwoods, cypress dome, and mangrove habitats are typically included in the district. The heterogeneity of the Ocala Uplift Physiographic District is reflected in the varied elevations found in the USF Eco Area. The highest elevation occurs in the sandhill plant community type at 18 meters (58 feet) above mean sea level (msl) (SWFWMD 1973 aerial photograph with contours). The lowest elevation occurs in the floodplain swamp at 7 meters (24 feet) above (msl). Slopes in the areas with more relief range between 2%. Over half of the USF Eco Area is comprised of wetlands (Figures 2, 5). The hydrology of the area is predominantly associated with Cypress Creek and the Hillsborough River. Figure 5. National Wetland Inventory (NWI) map of the University of South Florida Ecological Research Area showing the NWI wetland type classification. (Cowardin et al., 1979). 10
Soils types in the USF Eco Area range from extremely droughty, excessively drained sands, predominantly of the entisol soil order, to nearly permanently waterlogged muck and peat in the swamp, predominantly from the spodosol soil order (Figure 6) (Brown et al. 1990; Doolittle et al. 1989; Meyers 2000; Webb 1990). Figure 6. Soil type classification in the University of South Florida Ecological Research Area from the 1989 USDA/SCS Hillsborough County Soil Survey. (Doolittle et al. 1989). The entisols primarily include the Candler fine sand and Pomello fine sand soil types. The Chobee sandy loam, Felda fine sand, Immokalee fine sand, Malabar fine sand, and Myakka fine sand soil types are primarily spodosols. Topography, hydrology, and soils for each of the plant community types are dealt with in more depth and specificity in their respective descriptions. 11
12 METHODS Field Collections Documentation of the USF Eco flora was done by verification of plant voucher specimens in the USF Herbarium listed by Richardson et al. (1991) and by additional field collections made during the present study. Field collections of vascular plant voucher specimens were conducted from June 2001 through July 2005 in the USF Ec o Area with collection trips conducted during each season of the year throughout the five year period. Field characteristics, precise locality, habitat, plant associations, soil type (US DA/SCS 1989 Hillsborough County Soil Survey), elevation (SWFWMD 1973 aerial photograph with contours), and relative abundance (qualitative estimates of relative abundance of the vascular plan t species within the habitat collections were made), were recorded for each specimen collected. Collections were made in duplicate with the exception of plants that were on State of Flor ida rare and endangered species lists (Coile and Garland 2003). Plant voucher specimens were processed in accordance with standard field and herbarium techniques and deposited in the USF Herbarium. Identification of the plant voucher specime ns were primarily made utilizing Wunderlin (1998) and Wunderlin and Hansen (2003, 2005). Nomencla ture used is that of Wunderlin and Hansen (2003, 2005). Identified voucher specimens were verified by comparison with specimens in the USF Herbarium and confirmed by Richard P. Wunderlin and Bruce F. Hansen. Delineation and Characterization of Plant Communities Plant communities were initially delineated through photointerpretation using color infrared (CIR) (SWFWMD GIS Division 1999) (Figure 4B ) and black and white (Hillsborough County 2002) aerial photographs of the USF Eco Area. Ancillary data used for initial delineations
included the National Wetland Inventory (USDI/FWS/NWI 1988) (Figure 5), Hillsborough County Soil Survey (USDA/SCS 1989) (Figure 6), and the 1999 FLUCCS LEV 1 Land Use Map (SWFWMD 2004). The 1938 USDA/SCS Hillsborough County Soil Survey aerial photograph was used for historical reference of the plant communities and compared to the more recent 1999 color infrared (Figure 7). A. B. Figure 7. Historic and recent aerial photographs of the University of South Florida Ecological Research Area. A. 1938 black and white (USDA/SCS Hillsborough County Soil Survey 1938). B. 1999 color infrared (SWFWMD GIS Division 1999). Plant community delineations were verified and refined by ground truthing using a handheld Garmin GPS III Plus Global Positioning System (GPS) to acquire coordinate points for mapping delineations. Plant association data from specimen collections and general field observations were incorporated into the ground truthing. The Florida Natural Areas Inventory (FNAI) and Department of Natural Resources (DNR) classification system for the natural communities of Florida (FNAI and DNR 1990) was used for classification and characterization of the plant communities found in the USF Eco Area with additional information from Meyers and Ewel (1990) and Meyers (2000). A map of the USF Eco 13
14 Area plant communities was produced using the ESRI ArcGIS 8.2 (2001-2002) Geographic Information System (GIS) software. Data Organization The color infrared (CIR) (SWFWMD GIS Division 1999), black and white (Hillsborough County 2002), and USDA/SCS 1938 Hillsborough County Soil Survey aerial photographs and the USF Eco Area parcel boundary (SWFWMD GI S Division 2005), National Wetland Inventory (USDI/FWS/NWI 1988), Hillsborough County Soil Survey (USDA/SCS 1989), and the 1999 FLUCCS LEV 1 Land Use Map (SWFWMD 2004) images and data were put into the ESRI ArcGIS 8.2 (2001-2002) GIS software layers. Ground truthing and specimen collection locality coordinates were initially downloaded from th e handheld Garmin GPS III Plus GPS into the Garmin MapSource Version 3.02 (1999) GIS soft ware then imported into a Microsoft Excel 2002 database. All floristic and coordinate data were then imported from the Excel database into the ESRI ArcGIS 8.2 (2001-2002) GIS software layers. Plant community delineation for the Eco Area was finalized by digitizing the GPS ground truthing coordinate data into the above mentioned ESRI ArcGIS 8.2 (20012002) GIS software layers for mapping.
15 RESULTS AND DISCUSSION Floristics Verification of plant voucher specimens in the USF Herbarium, listed by Richardson et al. (1991), produced 312 vouchered taxa Additional collections from the present floristic inventory increased the number of vouchered taxa to 404. In the present study, 274 vascular plant taxa were collected and documented, 182 of which were present in the previous vouchered collections, and 92 are new additions to the flora. One hundred and thirty vouchered taxa from the previous collections were not recollected. The USF Eco Area flora, with the present flor istic inventory, consists of 404 vouchered taxa in 251 genera and 102 families (Table 1). Table 1. University of South Florida Ecol ogical Research Area floristic synopsis Taxa 1 Genera Families Native 2 Exotics 3 Endemics 4 County Records 5 Pteridophytes 12 10 10 7 5 0 0 Gymnosperms 5 2 2 5 0 0 0 Angiosperms (Monocotyledons) 122 56 19 115 7 2 2 Angiosperms (Dicotyledons) 265 183 71 251 14 11 2 Totals 404 251 102 378 26 13 4 1 Species and infraspecific taxa 2 Taxa whose natural range included Flor ida at the time of European contact in the sixteenth century 3 Taxa introduced into Florida from a natural range outside of Florida after European contact in the sixteenth century (non-native taxa) 4 Taxa confined within the geographic boundary of Florida 5 Hillsborough County first record of taxa presence in Hillsborough County
16 The vascular plant families with the largest representation are Asteraceae (51 taxa), Poaceae (41 taxa), Cyperaceae (34 taxa), and Fabaceae (27 ta xa). The most represented genera include Rhynchospora with 9 taxa; Cyperus Dichanthelium and Quercus with 8 taxa in each of the three genera; and Carex, Juncus and Polygala with 6 taxa in each genera. Of the 404 taxa found in the USF Eco Area, 378 (94%) are native to Florida a nd 26 (6%) are exotic (non-native) (Wunderlin 2003, Wunderlin and Hansen 2005) (Table 1). Of the 378 native taxa, 13 are endemic to Florida (Wunderlin 2003, Wunderlin and Hansen 2005) (Tables 1, 2). Table 2. Vascular plant taxa endemic* to Florid a occurring in the University of South Florida Ecological Research Area (Wunderlin and Hansen 2005) Arnoglossum floridanum Lythrum flagellare Asimina reticulata P hoebanthus grandiflorus Berlandiera subacaulis Polygala rugelii Carex vexans Scutellaria arenicola Chrysopsis linearifolia subsp. dressii Stipulicida setacea var. lacerata Chrysopsis subulata Tillandsia simulata Coreopsis leavenworthii *Endemic taxa taxa confined within the geographic boundary of Florida. Ten taxa (9 of the 26 exotic taxa and 1 of the 378 native taxa) are listed as invasive by the Florida Exotic Pest Plant Council (FLEPPC) (FLEPPC 2003 ). Seven are listed as FLEPPCs Category I invasive species and 3 are listed as Category II inv asive species (Tables 1, 3). Fortunately, the relative abundances of invasive taxa in the USF Eco Area are currently rare except for Alternanthera philoxeroides Eichhornia crassipes and Pistia stratiotes which are locally common in various areas of the Hillsborough Ri ver, Cypress Creek, floodplain swamp, and floodplain marsh.
17 Table 3. Florida Exotic Pest Plant Council listed invasive vascular plant taxa (FLEPPC 2003) found in the University of South Florida Ecological Research Area Category I* Category II** Eichhornia crassipes Alternanthera philoxeroides Lantana camara Rhynchelytrum repens Lygodium japonicum Urena lobata Nephrolepis cordifolia Pistia stratiotes Schinus terebinthifolius Urochloa mutica *Category I taxa that invade and alter the ecosystems of Floridas natural plant communities **Category II taxa that have shown inva sive properties and the potential to alter the ecosystems of Florida's natural plant communities Four taxa are new records for Hillsbor ough County (Wunderlin and Hansen 2005) (Tables 1, 4). Nine of the 404 taxa found in the USF Eco Ar ea are listed as either endangered, threatened, or commercially exploited by the Florida Department of Agriculture and Consumer Services (Coile and Garland 2003) (Table 5). Lythrum flagellare is one of most notable of the collections in that it is an endangered endemic taxon and a new record for Hillsborough County. Previously, L. flagellare had only been found in 11 Florida counties and had a disjunct distribution; Hernando and Orange counties in Central Florida and then Manatee, Sarasota, DeSoto, Okeechobee, Charlotte, Glades, Lee, Hendry, and Collier counties in Southwest and South Central Florida. Table 4. New records of vascular plant t axa for Hillsborough County found in the University of South Florida Ecological Researc h Area (Wunderlin and Hansen 2005) Echinochloa muricata Hypoxis wrightii Lechea minor Lythrum flagellare
18 Table 5. University of South Florida Ecological Research Area vascular plant taxa listed as endangered, threatened, or commercia lly exploited by the Florida Department of Agriculture and Consumer Services (Regulated Plant Index, Rule 5B-40.0055) (Coile and Garland 2003) Endangered Threatened Commercially Exploited Lythrum flagellare Pinguicu la caerulea Encyclia tampensis Matelea pubiflora Pteroglossasp is ecristata Epidendrum conopseum Tillandsia fasciculata var. densispica Zephyranthes atamasca Osmunda regalis var. spectabilis Plant Communities Classification of the USF Eco Area natural plant community types is based primarily on the Florida Natural Areas Inventory and Department of Natural Resources classification system (FNAI and DNR 1990), supplemented by Meyers and Ewel (1990) and Meyers (2000) along with field observations throughout the research period. Twelve plant community types are recognized in the USF Eco Area. Eleven are plant community types found in the natural areas (245 ha, 80%) and one is a community type that is continually di sturbed (61 ha, 20%) (Table 6) (Figures 8, 9). The majority of the USF Eco Area is made up of wetlands, which fall under the riverine and palustrine natural community categories. Th e Hillsborough River and Cypress Creek riverine ecosystems represent the blackwater stream natural plant community type (3 ha, 1%) (Table 6) (Figures 8, 9). The palustrine ecosystems consist of the floodplain swamp (128 ha, 42%), floodplain forest (18 ha, 6%), floodplain marsh (14 ha, 5%), hydric hammock (10 ha 3%), seepage slope (3 ha, 1%), and wet flatwoods (22 ha 7%) natural plant community types (Table 6) (Figures 8, 9). The mesic flatwoods (23 ha, 8% ), scrubby flatwoods (4 ha, 1%), sandhill (13 ha, 4%), and xeric hammock (7 ha, 2%) natural plan t community types, found in the uplands of the USF Eco Area, represent the terrestrial natural community category (Table 6) (Figures 8, 9). The ruderal/developed community type (61 ha, 20%) in the USF Eco Area includes the continually
disturbed and developed areas composed of the USF Golf Course, Riverfront Park, storage and dumping sites and areas along roads, fences, and firebreaks (Table 6) (Figures 8, 9). Table 6. Areas of the twelve plant communities found in the University of South Florida Ecological Research Area Plant Community Hectares Acres Floodplain Swamp (FS) 128 317 Ruderal/Developed 1 (RD) 61 150 Mesic Flatwoods 2 (MF) 23 57 Wet Flatwoods (WF) 22 54 Floodplain Forest (FF) 18 46 Floodplain Marsh (FM) 14 35 Sandhill (SH) 13 31 Hydric Hammock 3 (HH) 10 25 Xeric Hammock 4 (XH) 7 17 Scrubby Flatwoods (SF) 4 10 Blackwater Stream 5 (BS) 3 7 Seepage Slope (SS) 3 7 Total 306 6 756 6 1 USF Golf Course and USF Riverfront Park as well as dump and storage sites and along roads, fences, and firebreaks 2Dome Swamps (DS) and Sinkholes (SI) included 3Dome Swamp (DS) included 4Sandhill (S) and Sand Pine Scrub (SPS) climax community 5Hillsborough River and Cypress Creek 6Total of just the natural areas is 245 hectares (ha) or 606 acres (a), excluding Ruderal/Developed (RD) 19
Figure 8. The University of South Florida Ecological Research Area plant community types. The wetlands are comprised of Blackwater Stream, Floodplain Swamp, Floodplain Forest, Floodplain Marsh, Hydric Hammock, Seepage Slope, and Wet Flatwoods. The uplands are comprised of Mesic Flatwoods, Scrubby Flatwoods, Sandhill, Xeric Hammock, and Ruderal/Developed. 20
87654321114220051015202530354045FSRDMFWFFFFMSHHHXHSFBSSSPlant CommunitiesPercent Area (%) Figure 9. Percent areas of the twelve plant communities found in the University of South Florida Ecological Research Area. Floodplain Swamp (FS), Ruderal/Developed (RD), Mesic Flatwoods (MF), Wet Flatwoods (WF), Floodplain Forest (FF), Floodplain Marsh (FM), Sandhill (SH), Hydric Hammock (HH), Xeric Hammock (XH), Scrubby Flatwoods (SF), Blackwater Stream (BS), Seepage Slope (SS). Observations during the current survey revealed definite distributional patterns of mixed species assemblages occurring together consistently in specific abiotic and biotic environmental conditions, enough to recognizable in their designated natural plant community types. The USF Eco Area natural plant communities, delineated and classified above, do not have sharply defined 21
22 and discrete boundaries. Ecotones between communi ty types vary in width with minimal to much species overlap from abutting communities. Ecological co mmunities are dynamic, shifting spatially and compositionally th rough time, and rarely have discrete and permanent boundaries (Gurevitch et al. 2002; Stiling 1999; TNC 1996). Mo st likely, the USF Eco Area natural plant communities will shift spatially and compositionally, in time, as a result of changes in abiotic and biotic factors and/or anthropogenic perturbations. For convenience, the observed species assemblages, as they presently o ccur in the USF Eco Area, are referred to as natural plant communities. A natural plant community, in the current study, is defined per FNAI and DNR (1990). Natural plant community types in the USF Eco Area are delineated and classified to facilitate the inventory, analysis, evaluation, and monitoring of the mixed species assemblages and their associated ecosystems for purposes of research, education, planning, management, conservation, and potential restoration. Riverine Community The riverine community in the USF Eco Area consists of the blackwater stream community type. Blackwater streams are the most dominant and widely distributed type of river system found in peninsular Florida (FNAI and DNR 1990; Meyers 2000). Blackwater Stream The blackwater stream community in the USF Eco Area covers approximately 3 ha (7 a) or 1% of the total USF Eco Area plant communities and is composed of two riverine systems; Cypress Creek and the Hillsborough River (Table 6) (Figures 8, 9, 10). Despite the small percentage of blackwater st ream community in the USF Eco Area, the two riverine systems are highly interdependent a nd tightly interwoven with the USF Eco Areas palustrine systems of the floodplain swamp, forest, and marsh and hydric hammock community types.
A. B. Figure 10. The blackwater stream plant community type in the University of South Florida Ecological Research Area (USF Eco Area). A. Cypress Creek as it enters the northwest corner of the USF Eco Area. B. The Hillsborough River makes up the eastern border of the USF Eco Area. (Photograph courtesy of Ben Mercadante). 23
24 Blackwater streams can be both perennial and seasonally intermittent streams (FNAI and DNR 1990; Meyers 2000; Nordlie 1990). Depending on th e topography along their watercourses, they can alternately become deep channels confined by steep or low-lying banks; networks of braided streams that create islands of palustrine or upland vegetation; and intermittent streams, periodically disappearing into the low topography of floodplain communities and then occasionally reemerging. The flow in the Hillsborough River and Cypress Creek ranges from moderate to swift which creates shifting sands in the streambed in some areas and incised deep channels with steep banks in others. Typical of blackwater streams, their water levels go through considerable seasonal fluctuations. The water of blackwater streams is gene rally acidic, but may become more neutral when stream water is influenced by alkaline ground wa ter at times of low water levels (FNAI and DNR 1990; Meyers 2000; Nordlie 1990). The Hillsbor ough River and Cypress Creek both have the coffee/tea-colored water, characteristic of blackwater streams, as a result of the high tannin content and rich organic debris accumulated fro m their headwaters originating in extensive wetlands with organic soils. Particulate and di ssolved organic matter overlay a sandy riverbed bottom that is often underlain with limestone. Although limestone is typically exposed periodically along their watercourses, this does not occur in the USF Eco Area. Emergent, floating, and s ubmerged vegetation is ge nerally minimal in mid-channel in the USF Eco Area blackwater streams due to the dark wate rs limiting light penetration for photosynthesis. The periodic steep banks, deep channels, and seasonal wide fluctuations in water levels create an unstable habitat for vegetation to take hold. However, emergent, floating, and submerged vegetation occurs in the sloughs as well as in the shallower and slower moving areas along the edges of the streams. Both Cypress Creek, approximately 70 kilometers (km) or 40 miles (mi) in length, and the Hillsborough River, approximately 88 km (55 mi) in length, run within the boundaries of Florida.
25 Cypress Creek originates in a vast expanse of ma rsh in Pasco County, around San Antonio, north of the USF Eco Area. From there it meanders south and eventually becomes one of the major tributaries that feed into the Hillsborough River. Along its watercourse, the natural flow of Cypress Creek has been altered by flood control st ructures, diking, artificial channeling, channel diversions, and drawdowns in water well field areas. Cypress Creek enters the USF Eco Area on th e northwest corner just east of the golf course (Figure 10A). It runs in a deeply incised natu ral channel and slowly flows south for roughly 170 meters (m) or 558 feet (ft). Here the creek is approximately 10 m (33 ft) wide, bounded by steep banks of floodplain vegetation, and very little vegetation mid-channel. Cypress Creek then turns to the west southwest, for roughly 160 m (525 ft), where it starts to break up into a braided stream as the elevation drops into the floodplain forest and swamp. There, the main channel narrows even more, the banks are not as steep, and the stream flow quickens. As the main channel begins to twist, turn, and oxbow, it creates small is lands composed of floodplain forest and swamp vegetation and becomes hard to distinguish fro m the other broken off streams. Accumulated organic debris and fallen trees from flood events cau se more diversions of the braided streams as well as pockets of ditched areas. As Cypress Creek meanders through the fl oodplain forest and west through the broad, low relief of floodplain swamp, just north of Buck Island, the main channel and braided streams become even more undefined, eventually alternating between ephemeral de tritus filled and highly acidic swamp streams and more defined channels Once through the floodplain swamp, the main channel comes together again with low lying banks. The defined channel here is roughly 12 m (39 ft) wide and runs approximately 80 m (262 ft) before it empties into the Hillsborough River on the northeast corner of the USF Eco Area. Due to the extent of undefined and low-lying channels through the floodplain communities and the blackwater stream characteristic
26 fluctuations of extreme to low flows, any floodwater or discharge easily causes Cypress Creek to overflow its banks, flooding the floodplain forest and swamp. The Hillsborough River headwaters are in the southern portion of the 2,253 square kilometer (870 square mile) expanse of the Green Sw amp that extends into Sumter, Pasco, and Hillsborough Counties. On its a pproximately 88 km (55 mi.) path from the Green Swamp, the Hillsborough River winds southwest through Crys tal Springs in Zephyrhills, the Hillsborough River State Park, Lettuce Lake Park and the USF Eco Area (Bray 2004). Just north and south of the USF Eco Area the natural flow and water leve l fluctuations of the Hillsborough River become altered by the dam structures of the City of Ta mpas Hillsborough River Reservoir, built in the 1920s, and the diversion and impound ment structures of the Tampa Bypass Canal and the Lower Hillsborough River Flood Detention Area, built in the 1960s and 1970s for flood control (Bray 2004). Once through the impoundment and divers ion controls, the Hillsborough River winds through downtown Tampa and then finally empties into the mouth of Tampa Bay. The entire eastern border of the USF Eco Area, approximately .9 km (.6 mi) in length, is on the Hillsborough River (Figure 10B). The flow of th e river is a slow run from north to south with a wide channel that cuts through the low topography of floodplain swamp and marsh. Little to no vegetation is found mid-channel but emergent and floating emerge nt vegetation occurs along the edges of the river. The channel width along the USF Eco Area ranges from approximately 80 m (262 ft) where Cypress Creek empties into the river at the north end, to a width of 200 m (656 ft) in the Lettuce Lake area, and to 30 m (98 ft) wide at Riverfront Park at the southeast corner of the USF Eco Area. The stretch of the Hillsborough River that makes up the eastern border of the USF Eco Area was historically a riverine system, but today is more of a lacustrine system due to the disruption of natural flow from the reservoir and flood control impoundment and diversion structures (Cowardin et al. 1979).
27 Hydrophyte tree species such as Acer rubrum Cornus foemina Fraxinus caroliniana, Gleditsia aquatica, Salix caroliniana Taxodium ascendens Taxodium distichum and Ulmus americana, found on the margins of the USF Eco Area blackwater streams, reflect the floodplain communities they cut through. Encylia tampensis Epidendron conopseum Psilotum nudum Tillandsia fasciculata var. denispica Tillandsia simulata, and Tillandsia usneoides are among the abundant epiphyte species filling the trees that hang over the streams. Herbaceous hydrophyte species, found along the edges of the streams, include Carex lupuliformis Osmunda regalis var. spectabilis Panicum hemitomon Polygonum densiflorum Rumex verticillatus Scirpus tabernaemontani and Typha domingensis. Submerged and emergent hydrophytes including Ceratopteris thalictroides Nuphar advena Pontederia cordata and Proserpinaca palustris, are present in the shallower and more sheltered ar eas of Cypress Creek and the Hillsborough River. Other emergent plants, such as Alternanthera philoxeroides, Bidens laevis Eichhornia crassipes Habenaria repens Paspalum repens and Polygonum punctatum create floating mats, especially where Cypress Creek empties into Hillsborough River. Azolla caroliniana Lemna aequinoctiali Pistia stratiotes Salvinia minima and Spirodela polyrhiza are locally common floating aquatic plants that carpet the surface waters in sloughs and slower parts of the streams. Centella asiatica, Cicuta maculata, Hydrocotyle verticillata and Micranthemum umbrosum are a few of the herbaceous plants that colonize dead snags that float in the channels or get caught in the accumulated debris on the edge of the streams. Mikania scandens and Symphiotrichum carolinianum scramble over debris and fallen trees that have accumulated in the sloughs and the shallower and slower areas of the Creek and River. Along with the negative impacts of impoundment and diversion structures, artificial channeling, diking, and drawdowns that disrupt the natural flow and water levels of Cypress Creek and the Hillsborough River, both blackwater streams have been altered by agriculture, development, and silviculture along their watercourses. Invasive species such as Alternanthera
28 philoxeroides Eichhornia crassipes and Pistia stratiotes have also contributed to altering their fragile ecosystems. Riverine systems are closely integrated with their associated wetland systems; alterations to either system will have an effect on the other (FNAI and DNR 1990; Nordlie 1990). Despite the above mentioned an thropogenic perturbations, Cypress Creek and the Hillsborough River watershe ds have been protected enough in parts by state, county, and local agencies to provide an oasis for wildlife, including endangered and threatened species and species of special concern, which is vital in these days of compromised wetlands and habitat fragmentation. Palustrine Communities The palustrine communities in the USF Eco Area consist of floodplain swamp, floodplain forest, floodplain marsh, hydric hammock, seepage slope, and wet flatwoods community types. The floodplain communities and the hydric hammoc k are generally intermixed. Differences in their community structure and species composition are due to subtle changes in topography and hydroperiod. The USF Eco Areas seepage slope community is a seepage wetland with impermeable soils. Wet flatwoods primarily make up the ecotone between the floodplain and terrestrial communities. Floodplain Swamp Riverine floodplain swamps are the most diverse and productive type of swamp in Florida (Ewel 1990; FNAI and DNR 1990; Meyers 2000). The hydrology of the USF Eco Area floodplain swamp community is dominated by Cypress Creek and the Hillsborough River. Covering approximately 128 ha (317 a) or 42% of the total area, the floodplain swamp is the most prominent plant community in the USF Eco Area (Table 6) (Figures 8, 9, 11). It is a mosaic of saturated black organic soils; pools of organic-stained standing water in depressions of accumulated organic debris; and hummocks created by buttresses of hydrophilic trees, royal
ferns, and flood distributed detrital accumulations that occasionally provide footholds for non-hydrophilic plant species. Figure 11. The floodplain swamp is the dominant plant community in the University of South Florida Ecological Research Area. (Photograph courtesy of Ben Mercadante). 29 Hydroperiod is the primary control over the ecological structure and seasonal species composition throughout the USF Eco Area floodplain swamp (Ewel 1990; FNAI and DNR 1990; Meyers 2000). Being a riverine floodplain swamp, the flowing waters and rapid seasonal fluctuations in water levels of Cypress Creek and the Hillsborough River create a relatively short hydroperiod, as compared to stillwater swamps, of approximately 6 months, typically from June
30 to February. However, the floodplain swamp in the USF Eco Area remains semipermanently flooded throughout the year, except during extreme droughts, with local differences in hydroperiod occurring within the swamp, that often shift seasonally as detrital accumulations are redistributed by periodic flood events. Although most of the surface water in the swamp is provided by the USF Eco Area blackwater streams, surface water is also contributed by seasonal local precipitation and runoff from impermeable soil layers of abutting communities. The swamp can remain inundated with floodwaters for extended pe riods of time after prolonged intense rains. Groundwater also contributes to the hydrology of the swamp, since the water table is at or close to the soil surface, especially during dry pe riods when surface water is at a minimum. The soils in the USF Eco Area floodplain swamp are made up of a variable mix of highly decomposed organic soils. Chobee sandy loam is the dominant soil type, recognized by its surface layer of black sandy loam underlain with mottled sandy clay loam and hydrological characteristics of very poorly drained, freque ntly flooded, and high available water capacity (Doolittle et al. 1989) (Figure 6). Pockets of mucky fine sand surface layers and considerable peat accumulations are also found throughout the swam p. The wide fluctuations in water levels of the rich, organic, flowing blackwater streams a nd the constant rearranging and transporting of accumulated organic debris, sediments, and nutri ents by periodic flood events make great contributions to the high productivity typically found within the floodplain swamp system. Fire frequency in floodplain swamps in general is low, occurring roughly once every century, except during periods of extreme drought, when satur ated organic litter and peat have dried out enough to carry fire (Ewel 1990; FNAI and DNR 1990; Meyers 2000). When they do occur, fires in floodplain swamps may burn slowly for an ex tended period of time, producing a great deal of smoke as a result of the peat accumulations and mucky organic soils. No records of fire occurrences in the USF Eco Area floodplain swamp have been found.
31 The USF Eco Area floodplain swamp reflects the characteristic vegetative structure of floodplain swamps associated with blackwater streams; a well developed forested canopy, dominated by deciduous needle and broad-leaved trees, thin mid and sub-canopy of mostly deciduous small trees and shrubs, and a sparse groundcover sprinkled with seasonal herbaceous plants and overstory seedlings, that disappear af ter prolonged periods of inundation (Cowardin et al. 1979; Ewel 1990; FNAI and DNR 1990; Meyers 2000). Throughout the USF Eco Area floodplain swamp, the most dominant upper canopy tree species is the needle-leaved deciduous Taxodium distichum Taxodium ascendens is more abundant along the margins of the Hillsborough Ri ver and scattered sparingly around the swamp. The broad-leaved deciduous trees, found in the upper canopy, are a mix of Acer rubrum Gleditsia aquatica, Nyssa sylvatica var. biflora and Ulmus americana Interestingly, the relative abundance of the Nyssa sylvatica var. biflora is rare throughout most of the swamp, except in the northwest corner. Many canopy tree species in the floodplain swamp have buttresses, an adaptation to withstand long periods of inundation (Ewel 1990). Hummocks, created by the buttresses of hydrophilic tree species, rhizomes of Osmunda regalis var. spectabilis and larger accumulations of debris, support many of the pl ant species mentioned above and below as well as less hydrophilic tree species, such as Quercus laurifolia and Sabal palmetto. In the portion of the swamp northwest of Buck Island, one ex ceptionally large hummock supports an old Pinus palustris a pine tree generally f ound in upland habitats. Fraxinus caroliniana is the most dominant mid-canopy tree species throughout the swamp. Closer to the Hillsborough River, it is generally more robust where it is often included in the upper canopy. The diversity of the mid-canopy is low, composed mostly of younger overstory trees, along with the ubiquitous F. caroliniana except for Cornus foemina, which occurs occasionally throughout the swamp, and Salix caroliniana occurring in areas of tree fall and along the margin of the Hillsborough River. The diversity of small trees is greater along the
32 margins of the swamp where Ilex decidua Ilex cassine and Myrica cerifera are included in the mid-canopy along with sub-canopy shrub species such as Sideroxylon reclinatum and Viburnum obovatum During the present study, it was observe d that certain shrubs in the sub-canopy seemed to trade off dominance in different portions of the swamp. Cephalanthus occidentalis was observed to be more dominant in the middle and eastern portions while Itea virginica was observed to be more dominant in the western portions. Campsis radicans and Toxicodendron radicans are vines that occur along the margins of the swamp. T radicans occasionally occurs on some of the hummocks as well. Encylia tampensis Epidendron conopseum Psilotum nudum Tillandsia bartramii Tillandsia fasciculata var. denispica Tillandsia recurvata Tillandsia simulata, and Tillandsia usneoides are among the abundant epiphytic plant species in the floodplain swamp. Ferns such as Osmunda cinnamomea Osmunda regalis var. spectabilis Thelypteris dentata Woodwardia areolata, and Woodwardia virginica occur in shallower areas and on hummocks. Some of the grasses and sedges that occur in the swamp are Echinochloa muricata Carex gigantea Panicum hemitomon Rhynchospora corniculata Rhynchospora microcarpa. Suffrutescent species such as Hypericum hypericoides Hypericum fasciculatum, and Ludwigia spp inhabit the margins of the swamp year round. The floodplain swamp has abundant overstory seedlings and herbaceous plants early in th e spring before the upper canopy closes. Boehmeria cylindrica ubiquitous throughout the swamp, and Asclepias perennis and Sabtia calycina with more of an occasional distribution, are some of the first herbs that begin to show in the spring. Eichhornia crassipes Polygonum spp. Sagittaria graminea var. chapmanii, and Utricularia inflata are emergent and floating herbaceous plants that are found in the standing water of depressions. Saururus cernuus occurs mostly in the shallower areas of the swamp, especially north northeast of Buck Island. Small seasonal herbs such as Centella asiatica Diodia virginiana Galium tinctorium, Hydrocotyle verticillata Hypericum mutilum Hypoxis curtisii
33 Micranthium umbrosum Packera glabella Ptillimnium capillaceum and Samolus valerandi are found on fallen trees and accumulated organic debris periodically throughout the year. After the floodwaters recede, they are also the firs t to appear in the saturated soils. Symphyotrichum carolinianum is occasionally found scrambling over la rger debris and fallen trees throughout. Anthropogenic alterations of the blackwater st reams natural fluctuations in water levels have compromised the natural cycles of hydroperiod in the USF Eco Area floodplain swamp. The intense logging of cypress in the past and the more recent drainage a nd filling for surrounding developments have also had a negative impact. Along with the above disturbances, the increasing populations of Eichhornia crassipes a FLEPPC Category I invasive species, are another threat to the swamps ecosystem. Yet, due to the inaccessi bility of the swamp and the protection of the blackwater streams watersheds, the USF Eco Area floodplain swamp remains a small protected island, in a sea of encroaching development, for many wetland species. Floodplain Forest The floodplain forest plant community type is found within the floodplain swamp therefore has similar characteristics in its hydrology, topography, soils, and fire frequency. It is distinguished from the floodplain swamp by occurring at slightly higher elevations, having a shorter hydroperiod, a nd a vegetative dominance of deciduous hardwood plant species (Ewel 1990; FNAI and DNR 1990; Meye rs 2000). Approximately 18 ha (46 a) or 6% of the USF Eco Area is composed of the flood plain forest plant community type (Table 6) (Figures 8, 9, 12). Areas of floodplain forest are found where Cypress Creek enters into the USF Eco Area on the northwest corner, north of the Riverfront Park camping area, and just west of Riverfront Park (Figure 8). Floodplain forests generally have a hydrope riod of inundation every one to two years for approximately 50% of the growing season (FNAI and DNR 1990). Periodic inundation of the USF Eco Area floodplain forest only occurs dur ing the occasional seasonal flood events after
prolonged intense rain. Although the water table depth is near the soil surface, it is lower than that of the floodplain swamp. During the dry season, there is no standing water. The high productivity of the floodplain forest system in the USF Eco Area, as in the floodplain swamp, is a beneficial result of the periodic flood events that move nutrient rich accumulated organic debris around the forest. A diverse mix of deciduous broadleaf hardwood plant species dominates the vegetative structure of floodplain forests (Cowardin et al.1979; Ewel 1990; FNAI and DNR 1990; Meyers 2000). Characteristically the vegetative structure is a well-developed forested upper canopy, a very open or dense mid and sub-canopy of smaller trees and shrubs, and an understory of seasonal herbs and overstory seedlings. Figure 12. Floodplain forest in the northwest corner of the University of South 34 Florida Ecological Research Area.
35 The largest and best example of floodplain forest, covering approximately 16 ha (39 a), is in the northwest corner of the USF Eco Area (Figures 8, 12). The upper canopy is cathedral-like, composed of a mix of very tall Acer rubrum Fraxinus caroliniana Quercus laurifolia Sabal palmetto and Ulmus americana Gleditsia aquatica and Taxodium distichum occur sporadically around the forest in the wetter areas. The mid-canopy is open and very sparse with few Carpinus caroliniana Cornus foemina Ilex cassine Ilex decidua and Myrica cerifera Cephalanthus occidentalis Itea virginica, Sabal minor Sideroxylon reclinatum Rubus argutus and Viburnum obovatum occur in the thinly distributed mix of shrubs in the sub-canopy. Vines that occur in the area are Campsis radicans Toxicodendron radicans and Vitis aestivalis Epiphytes such as Encyclia tampensis Tillandsia bartramii and Tillandsia simulata are found closer to the wetter areas of the floodplain forest, overhanging Cypress Creek and the edges of the forest where it drops into the swamp. Asplenium platyneuron a small fern, is also found in the trees. Nephrolepsis cordifolia a FLEPPC Category I invasive fern, is found on a few of the fallen trunks of trees. Fortunately the occurrence of N. cordifolia is rare in most of the floodplain forest. Other ferns such as Osmunda cinnamomea Osmunda regalis var. spectabilis Thelypteris interrupta and Woodwardia virginica occur on the forest floor. Some of the grasses and sedges that inhab it the USF Eco Area floodplain forest community are Axonopus furcatus Carax alata Carex lupuliformis Carex vexans Dichanthelium communtatum Oplismenus hirtellus Panicum hemitomon Rhynchospora colorata Rhynchospora fascicularis Rhynchospora microcarpa and Rhynchospora mixta Phanopyrum gymnocarpon is found in dense patches rooted in the mud in the lower elevations and on the edges of the braided streams and oxbows Cypress Creek has made as it cuts through the floodplain forest. Hypericum hypericoides and Psychotria sulzneri are among the suffrutescent plants found in the understory of the floodplain forest along with overstory seedlings. Asclepias perennis
36 Hypoxis curtissii Iris hexagona Sabatia calycina Sida rhombifolia Solidago leavenworthii Sisyrinchium angustfolium Viola lanceolata and Viola sororia are some of the seasonal herbaceous plants that have an occasional dist ribution throughout the forest. Carpeting the floodplain forest floor and periodically colonizing fallen trees and large organic debris are other seasonal herbaceous plants such as Commelina diffusa, Cardamine pensylvanica Centella asiatica Eclipta prostrata Eryngium baldwinii Hypericum mutilum Micranthemum umbrosum Phyla nodiflora and Samolus valerandi Saururus cernuus occurs in the wetter areas of the forest. Found scrambling over fallen trees and larger organic debris are Dichondra caroliniensis Melothria pendula and Symphyotrichum carolinianum Despite many of the above mentioned species occurring in all of the USF Eco Area floodplain forest communities, the overall vegetative structure is different. The floodplain forest communities found north of the Riverfront Park camping area, covering approximately 1 ha (3 a), and just west of Riverfront Park, covering approximately 1 ha (4 a), have a lower upper canopy, much denser mid and sub-canopy, and a more sparse herbaceous understory as opposed to the tall cathedral-like and open vegetative structure of the floodplain forest community in the northwest corner of the USF Eco Area (Figure 8). The Riverfront Park areas are much smaller and are mostly surrounded by fill from the park deve lopment therefore experience fewer flood events than the floodplain forest in the northwest corner, despite their close proximity to the Hillsborough River. Although the USF Eco Area floodplain forest plant communities have been negatively impacted by the same anthropogenic perturbations as the floodplain swamp, the inaccessibility of the deeper parts of the larger area of floodplain forest in the northwest corner of the USF Eco Area have remained so mewhat healthy and undisturbed. Floodplain Marsh The vegetative structure of the floodplain marsh plant community type is typically dominated by herbaceous perennial emer gent hydrophyte plant species with a sparse
37 sub-canopy of low deciduous shrubs and little to no mid and upper canopy (Cowardin et al. 1979; FNAI and DNR 1990; Kushlan 1990). Vegetation is r ooted in organic soils with a peat substrate that remains saturated or inundated with standi ng water throughout most of the year. Natural cycles of fluctuating water levels and a fire frequency of approximately every 510 years are important factors in maintaining the floodplain marsh vegetative structure by limiting peat accumulation and the invasion of woody shrub species. The floodplain marsh natural plant commun ity type, covering approxima tely 14 ha (35 a) or 5% of the USF Eco, is a low lying river edge marsh along the west side of the Hillsborough River that extends west into the floodplain swamp for approximately 213 m (700 ft) and runs from the southern edge of the east end of Cypress Creek down to just north of Riverfront Park (Table 6) (Figures 8, 9, 13). The fluctuating water le vels of both USF Eco Area blackwater streams influence the hydrology of the floodplain marsh community. It is distinguished from the floodplain swamp by a slightly lower elevation; longer annual hydroperiod of generally 7 months, when the marsh is flooded with flow ing water; higher peat accumulation; and a vegetative dominance of low deciduous woody shrubs. The 1938 USDA/SCS Hillsborough Count y Soil Survey aerial photograph and the 1988 National Wetland Inventory survey show the USF Eco Area floodplain marsh to have historically had the typical riverine marsh vegetative structur e dominated primarily by emergent hydrophytes (Figures 4, 5). During the present study, the vegetative structure of the USF Eco Area floodplain marsh was found to be low in diversity, dominated by only two deciduous woody shrub species, averaging less than 9 m (30 ft) in height, with very few emergent hydrophyte plant species. Along with the invasion of woody shrubs, the marsh is also filled with large organic debris and many fallen, dead shrubs. Salix caroliniana and Cephalanthus occidentalis are the two dominant woody shrub species that occur in the USF Eco Area floodplain marsh. Myrica cerifera, Quercus laurifolia and
Figure 13. Floodplain marsh in the University of South Florida Ecological Research Area is found west of the Hillsborough River. Ulmus americana are found on the few hummocks that occur on the edges of the marsh. The fern Osmunda regalis var. spectabilis occasionally appears on the hummocks as well. Hydrocotyle ranunculoides, occurring in large floating mats, is the most dominant herbaceous emergent plant species in the marsh. Polygonum punctatum and Eichhornia crassipes occur occasionally throughout. Azolla caroliniana, Lemna aequinoctialis, Pistia stratiotes, Salvinia minima, and Spirodela polyrhiza are floating aquatics that usually carpet the surface water. Mikania scandens is abundant, draped over fallen shrubs and larger organic debris. Boehmeria cylindrica and small herbaceous non-hydrophyte seasonal plant species, found also in the blackwater streams and floodplain swamp, colonize floating logs, larger organic debris, and the few hummocks in the marsh. 38
39 The current low diversity and shrub domi nated vegetative structure in the USF Eco Area floodplain marsh plant community reflects the impact of the previously mentioned alterations to the USF Eco Area blackwater streams hydrological regimes. Disruption of the natural cycles of hydroperiod and water level fluctuations has also produced conditions in the marsh that are not conducive to the fire frequency needed to maintain the historic typical floodplain marsh. Hydric Hammock The hydric hammock plant community type occurs in the upper zones of riverine floodplain swamps where the underlying lim estone layer is generally closer to the soil surface (Cowardin et al. 1979; Ewel 1990; FNAI and DNR 1990). There are three areas of hydric hammock that, in total, cover approximately 10 ha (25 a) or 3% of the USF Eco Area (Table 6) (Figures 8, 9, 14). A small area of hydric hammock, covering approximately 1 ha (3 a), grades north into the floodplain swamp from the wet flatwoods in the southwestern portion of the USF Eco Area (Figure 8). The largest area of hydric hammock, covering approximately 8 ha (20 a), occurs in the central northeast portion of the USF Eco Area and is surrounded by floodplain swamp to the east, northeast, south, and west northwest and wet flatwoods to the southwest (Figure 8). The area of floodplain forest community north of the camping area, west of Riverfront Park, grades into a small, approxima tely 1 ha (2 a) area of hydric hammock surrounded by floodplain swamp to the north (Figures 8, 14A). As in the USF Eco Area floodplain forest communities, the vegetative structure of the hydric hammock community type is dominated by a mix of broad-leaved, mostly deciduous, hardwood plant species in the upper, mid, and sub-canopies. Vegetation is distinguished from the floodplain forest by a greater abundance of Sabal palmetto and a vegetative species composition that typically has a wider range of tolerances for su rvival in upland habitats as well as in habitats with soils that remain saturated for s hort periods of time after heavy rains.
A. B. Figure 14. University of South Florida Ecological Research Area hydric hammock. A. Hydric hammock community west of Riverfront Park. B. Dome swamp. 40
41 Hydrology in the hydric hammock also differs from the surrounding floodplain communities in that the main water source primarily comes from deep groundwater seeping from the underlying limestone layer and local rainfall even ts (Cowardin et al. 1979; Ewel 1990; FNAI and DNR 1990). Hydroperiod in the USF Eco Area hydric hammock communities is typically less than 60 days annually, when soils are only tem porarily flooded periodically during the growing season rains. The soils are the same variab le organic soils of the surrounding floodplain communities but differ in that they have more sand and less peat in their composition and that the underlying limestone is closer to the soil surface. Fire frequency is rare, as in the floodplain swamp and forest, due to the vegetative struct ure and plant species composition of the hydric hammock communities not being conducive to fire and the saturated conditions of the surrounding floodplain communities. Within the western portion of the larger hydric hammock plant community in the USF Eco Area, there is a very small circular dome sw amp; a stillwater swamp where dissolution and collapse of the underlying limestone layer has created a small depression (Figure 14B). The dome swamp was not mapped separately because of its relatively small size. The soils in the dome swamp are acidic and very poorly drained. They are mostly composed of peat and muck over the organic sands that had slumped into th e depression and are underlain by an impermeable layer of clay hardpan. Groundwater seepage, rainwater, and run-off from the surrounding hydric hammock community are the main water sources for the dome swamp. Water is retained for a longer duration in the deeper central portion than in the shallower periphery of the dome swamp. Taxodium distichum is the dominant tree species in the dom e swamp and has a taller habit in the center of the dome, where the hydroperiod is longer than in the outer portions. Within the dome there is very little vegetation except for Cephalanthus occidentalis and a few of the same floating aquatics found in the USF Eco Area blackw ater streams and floodplain marsh. Osmunda
42 cinnamomea occurs in the ecotone between the hydric hammock community and the dome swamp, whereas Osmunda regalis var. spectabilis occurs within the dome swamp. The vegetative structure of the USF Eco Area hydric hammock plant community type includes an upper canopy with a mix of primarily broad-leaved, mostly deciduous, hardwood tree species, a sparse mid-and sub canopy of mostly young overstory trees and shrubs that can be dense in some areas and open in others within the same hydric hammock. The herbaceous groundcover is mostly a mix of many low seasonal species. Quercus laurifolia is the dominant tree species in the upper canopy. Sabal palmetto occurs frequently throughout and Quercus virginiana occasionally occurs on the periphery adjacent to wet flatwoods. Acer rubrum and Ulmus americana are occasional throughout. Fraxinus caroliniana Gleditsia aquatica, and Taxodium distichum occur more abundantly on the edges abutting the floodplain swamp whereas they are rarely found in the center. The mid-canopy frequently contains Ilex decidua while Ilex cassine only occurs occasionally throughout the community. Cornus foemina and Myrica cerifera occur occasionally at the edges of the hammocks and are found infrequently throughout. The sub-canopy includes a mix of shrubs that include Sabal minor Sideroxylon reclinatum and Viburnum obovatum The latter periodically forms dense thickets. Vines include Ampelopsis arborea Berchemia scandens Campsis radicans Gelsemium sempervirens, Parthenocissus quinquefolia Smilax auriculata Toxicodendron radicans, Vitis aestivalis and Vitis shuttleworthii There is a large patch of Vitis shuttleworthii in the center of the largest area of hydric hammock. Tillandsia recurvata and Tillandsia usenoides are epiphytes that occasionally occur throughout the community. Few pteridophytes occur in the USF Eco Area hydric hammocks. Osmunda regalis var. spectabilis occurs occasionally in the ecotones between the hydric hammocks and the floodplain
43 swamp. Thelypteris interrupta and Woodwardia virginica occur in the ecotone and the outer portions of the hydric hammocks near the floodplain swamp. The herbaceous groundcover includes ma ny grasses and sedges, and a few rushes. Common grasses that occur in the hydric hammocks are Axonopus furcatus Panicum hemitomon Panicum rigidulim Dichanthelium commutatum, Dichanthelium dichotomum, and Dichanthelium portoricense Carex gigantea is a sedge that occurs on the periphery of the hammocks. Rhynchospora colorata, Rhynchospora corniculata, and Rhynchospora microcarpa are other sedges that are found throughout. Rhynchospora mixta carpets the floor of the hydric hammock north of the floodplain forest community, north of the camping area, and is frequently found in the other hydric hammock communities in the USF Eco Area. Juncus marginatus is a rush that occurs on the edges and in the lower elevations of the hammocks. The suffrutescent species Hypericum hypericoides commonly appears in the ecotone between the hammocks and swamp. In the hammocks, it is sparsely distributed throughout or occurs occasionally in locally common groups. Asclepias perennis is a herbaceous perennial that is found along the edges of the hydric hammocks and the floodplain swamp in the spring. Viola lanceolata is abundant in the early spring on the floor of the hammocks along with an occasional distribution of Viola sororia. In late spring, Sisyrinchium angustifolium is evident and has an occasional to frequent abundance as a herbaceous groundcover. Cardamine pensylvanica Eryngium baldwinii Galium tinctorium Hydrocotyle verticillata, Hypoxis curtissii Oxalis corniculata, Phyla nodiflora Packera glabella and Ptilimnium capillaceum are some of the other low seasonal herbs that occur occasionally. Coreopsis leavenworthii is abundant throughout while Cirsium nuttallii Erechtites hieraciifolius Erigeron quercifolius Pluchea rosea and Sabatia calycina have a more occasional distribution. Lythrum flagellare the Florida endangered, endemic taxon, and new record for Hillsborough
44 County, is found in an open area on the hammock side of the ecotone between the floodplain swamp and the largest hydric hammock. The USF Eco Area hydric hammock plant communities are difficult to differentiate from denser floodplain forest plant communities around Riverfront Park. The vegetative structure and species composition are similar. During the present study, Carpinus caroliniana Cornus foemina Gleditsia aquatica, and Taxodium distichum were observed to occasionally occur throughout the floodplain forest communities whereas Carpinus caroliniana was rarely observed to occur in any of the hydric hammock communities in the USF Eco Area and Cornus foemina Gleditsia aquatica, and Taxodium distichum were rarely observed except on the periphery of the hydric hammocks, just in from the ecotone abutting the floodplain swamp. It was also observed that there was more of a frequent distribution of Sabal palmetto throughout the hydric hammock communities than in the floodplain forest communities. Despite the primarily groundwater hydrol ogical regime of the USF Eco Area hydric hammock communities, they are affected by the anthropoge nically altered hydrological regime of the USF Eco Area blackwater streams. Unnatural cycles of hydroperiod and fluctua ting water levels could possibly accelerate succession of the hydric ha mmock plant communities into either a mesic mixed hardwood plant community or a plant community dominated by hydrophytes depending on the drawdown and flooding periodicity. Seepage slope The seepage slope plant community type is a wetland formed by water percolating down gentle to steep slopes. A seepag e zone is created when the water gets caught in abutting terraced areas or bases of slopes that have an underlying impermeable layer of clay or hardpan (Cowardin et al. 1979; Ewel 1990; FNAI and DNR 1990; Meyers 2000). The constant seepage down slope maintains saturated conditions in the seepage zones overlying soils of organic sands and peat most of the year except during extreme droughts. Although rarely
45 inundated, water may pool in the deeper zones of the community forming boggy areas of meadows or open water. Seepage slope comm unities are characterized by a sparse upper and mid-canopy that may be periodically composed of stunted trees, a sub-canopy of mostly hydrophytic shrubs, and a dense and diverse herb aceous layer dominated by a boggy groundcover of sphagnum moss. Carnivorous and mycorrhizal plant species abound in the nutrient-poor acidic soils. Denser canopies of trees and shrubs are ofte n prevented by a fire frequency of 5 years or less. Covering approximately 3 ha (7 a) or 1% of the USF Eco Area, the seepage slope plant community is a catchment that runs north to sout h at the base of the western side of the central sandy upland ridge that dips north into the floodplain swamp (Table 6) (Figures 8, 9, 15). The southern end of the community turns west where it becomes a small more concentrated catchment juxtaposed between sloped upland plant commun ities on three sides. The seepage slope is bounded on the east by the sloped sandy upla nd communities of scrubby flatwoods, xeric hammock, and sandhill, from the north to sout h respectively, that grade down into mesic flatwoods with approximate slopes of 24% fro m approximate elevations of 9 m (30 ft) above msl; on the southeast, south, and south southwest by the sandhill community that grades down into mesic flatwoods with approximate sl opes of 4% from approximate elevations of 17 18 m (55 ft) above msl; on the northwest by a scrubby flatwoods community that grades east into wet flatwoods with an approximate slope of 2% from an approximate elevation of 9 m (31 ft) above msl; and by a wet flatwoods ecotone in to the floodplain swamp with approximate elevations of 7 m (256 ft) above msl on the w est southwest, west, north at the northern end, and north where the southern end of the community turns west (Figure 8). The source of the hydrological regime is primarily the down slope seepage from the sandy upland communities being caught by the impermeable clay and hardpa n in the underlying soils of the wet flatwoods ecotone. Rainfall events also contribute to the hydrology.
Figure 15. The seepage slope is one of the smallest plant communities found in the University of South Florida Ecological Research Area. The 1938 USDA/SCS Hillsborough County Soil Survey aerial photograph shows that historically the USF Eco Area seepage slope was primarily open, with sparse upper, mid, and sub-canopies that included several depressions forming areas of boggy meadows and open water; 46
47 the largest of which occurring where the southern end of the community turns west (Figure 4). During the present study, the overall vegetative struct ure of the community was found to be fairly dense in the upper and mid canopies with a mix of somewhat stunted, almost dwarfed, deciduous and evergreen, broad and needle-leaved wood y vegetation, the stunted, more dwarfed characteristic of the woody vegetation being most prevalent in the small, concentrated catchment at the southern end of the community; a sparse sub-canopy of mostly hydrophytic shrubs; and a dense herbaceous layer in saturated soils periodically carpeted with Sphagnum sp. Throughout the community, lichens and moss cover woody vegetation and low hummocks of varying sizes that have formed by built up soil, r oots of trees, or the rhizomes of O smunda regalis var. spectabilis As the community runs north to south along the base of the western side of the central upland ridge, there are many notable, almost circular depressions of varying sizes and composition that form boggy meadows of primarily one to two c oncentrated herbaceous species that may be remnants of the areas of boggy meadows or open wa ter in the above mentioned 1938 aerial. In the northeast portion of the small, more concentr ated catchment at the southern end of the community there is a small, slightly kidney shaped, boggy meadow, approximately 2 m (7 ft) wide by 10 m (33 ft) long, which may be a remnan t of the larger area of boggy meadow or open water noted in the 1938 aerial. Quercus laurifolia dominates the low upper canopy throughout, whereas Acer rubrum Quercus virginiana and Pinus elliottii are only found occasionally throughout. Q. laurifolia Q. virginiana and P. elliottii are often supported by the low hummocks. Stunted Taxodium distichum occur occasionally throughout the upper canopy in the small, concentrated catchment at the southern end of the community. The mid-canopy, dominated by Myrica cerifera includes an occasional occurrence of Ilex cassine and a rare occurrence of Ilex decidua and Ilex opaca Vaccinium arboreum is
48 periodically found in the mid-canopy, either s upported by the low hummocks or in areas of the community abutting the mesic flatwoods. Vaccinium corymbosum is the most dominant shrub throughout the sub-canopy. Also included in the sub-canopy are; an occasional occurrence of Cephalanthus occidentalis in the small, more concentrated catchment, and occasional occurrences of Sideroxylon reclinatum Vaccinium myrsinites and Viburnum obovatum where the community runs north to south at the western base of the central upland ridge. Throughout, the low hummocks occasionally support the less hydrophytic Serenoa repens especially where the community abuts the mesic flatwoods. Occasional vines include Ampelopsis arborea Campsis radicans Parthenocissus quinquefolia Smilax auriculata and Vitis shuttleworthii. Epiphytes occasionally include Tillandsia recurvata and Tillandsia usneoides O smunda regalis var. spectabilis Woodwardia areolata, and Woodwardia virginica are pteridophytes that occur more frequently in the small, more concentrated catchment at the southern end and occasionally throughout the rest of the community. W. virginica occasionally occurs in locally common groups where the community runs north to south at the western base of the central upland ridge. Andropogon glomeratus var. glaucopis Andropogon glomeratus var. pumilus Andropogon virginicus var. glaucus Axonopus furcatus Carex verrucosa Eleocharis vivpara Juncus effusus subsp. solutus Juncus marginatus Juncus repens Panicum hemitomon and Rhynchospora fascicularis are some of the grasses, sedges, a nd rushes that are included in the herbaceous layer. Suffrutescent species, occasionally included throughout, are Hypericum crux-andreae Hypericum fasciculatum Hypericum hypericoides and Hypericum tetrapetalum Herbaceous species such as Cirsium nuttalii the endemic Coreopsis leavenworthii Eriocaulon decangulare Lachnanthes caroliana Lachnocaulon anceps Mitchella repens Oldenlandia uniflora, Pluchea rosea Rhexia mariana Sabatia grandifolia. Syngonanthus flavidulus Viola lanceolata Xyris
49 elliottii and Xyris caroliniana are found throughout the community. The seepage slope community is one of the few areas in which the terrestrial orchid, Calopogon tuberosus occurs; primarily in the small, more concentrated catchment at the southern end. Drosera capillaris and Utricularia subulata are two carnivorous plants that frequently occur throughout the herbaceous groundcover. The many open, often circular, boggy depressions of varying sizes, occurring in the portion of the community running north to south along the western base of the central upland ridge, include varying mixtures of one to two concentrated combinations of herbaceous species. Some examples of the varying combinations include a dominance or co-dominance of either Andropogon glomeratus var. glaucopis Eriocaulon decangulare Lachnanthes caroliana Syngonanthus flavidulus or Xyris elliottii that may or may not include a scattering of the above mentioned dominant/co-dominant sp ecies along with a scattering of Drosera capillaris Panicum hemitomon Rhexia mariana Sabatia grandifolia ; patches of Woodwardia virginica with a scattering of Rhynchospora fascicularis ; or just monotypic mats of Axonopus furcatus Eleocharis vivpara, Juncus repens or one of the above mentioned dominant/co-dominant species. Eriocaulon decangulare and Lachnanthes caroliana both dominate the small, kidney shaped, boggy meadow in the northeast portion of the small, more concentrated catchment at the southern end; the former is common in the western porti on of the meadow and the latter is more frequent in the central and eastern portion. The fragile ecosystem of the seepage slope community is extremely susceptible to disturbances and threats that may in turn have the potential to irreversibly alter the community (Ewel 1990; FNAI and DNR 1990; Meyers 2000). Th e saturated condition of the soils makes the vegetative structure and plant species compositi on particularly vulnerable to trampling. Unnatural cycles of drawdowns and flood even ts caused by the anthropogenically altered hydroperiod of the USF Eco Area blackwater stream s may pose a threat to the hydrology of the
50 community as a result of its close proximity to the floodplain swamp. The hydrology and the continuum of the USF Eco Area seepage slope, as a w hole, has also been potentially altered by an old, raised dirt road that cuts off the small, more concentrated catchment at the southern end from the rest of the community. Lack of fire is also a threat, as mentioned above. A carefully prescribed fire regime may help reduce the growing density of the upper canopy as well as potentially promote more diversity in the shr ub and herbaceous species composition that is characteristic of seepage slope communities. Wet Flatwoods The wet flatwoods plant community type covers approximately 22 ha (54 a) or 7% of the USF Eco Area and is an integral pa rt of the fire-dependent, open-canopied, pine flatwoods matrix that includes the mesic and scrubby flatwoods community types (Table 6) (Figures 8, 9, 16). The ecotone between the palu strine and terrestrial communities is primarily made up of the wet flatwoods community type (Figures 8, 16A). Scattered patches of the community are also found imbedded within the mesic and scrubby flatwoods communities throughout (Figures 8, 16B). Because of their re latively small sizes, the imbedded patches were not mapped separately. Differences in the hydrology, vegetative structure, and species composition between the three pine flatwoods community types are strongly influenced by subtle changes in topography and edaphic conditions (Abrahamson and Hartnett 1990; Doolittle et al. 1989; FNAI and DNR 1990; Meyers 2000). The wet flatwoods community occurs in the lower lying elevations and shallow depressions of the pine flatwoods matrix where th e soils are very poorly drained. The nutrient poor, acidic sandy soils, primarily Malabar fine sa nd, are underlain by an impermeable layer of clay or hardpan. Percolation of water is c onsiderably reduced up or down through the hardpan layer. In order to withstand the complex ed aphic conditions of the community, vegetation is hydrophytic at the same time xerophytic; adapte d to survive the stresse s of seasonal inundation
51 for one to a few months per year during the rainy season and dehydra tion during the dry season when roots are unable to penetrate the hardpan laye r to reach the lowered water table. Vegetation is mostly pyrophytic as well; adapted to and dependent on a periodic fire frequency of 3 years. The vegetative structure of wet flatwoods is typically an open upper canopy of pine trees; an insignificant mid-canopy, an open to dense s ub-canopy of shrubs, and an open to dense herbaceous layer of grasses, sedges, rushes, and forb s. Variation in the densities of the vegetative structural layers as well as the species composition and diversity generally reflect fire frequency and disturbance history (Abrahamson and Hartnett 1990; Doolittle et al. 1989; FNAI and DNR 1990; Meyers 2000). In the USF Eco Area, the vegetative structur e is variable in the wet flatwoods community that makes up the ecotone between the wetland and upland communities. It ranges from being consistent with the typical vegetative structure of the community type to being more closed in the upper and mid-canopies with a higher percentage of hardwood tree species. Most of the ecotone around Buck Island, east of the patch of scrubby flatwoods northwest of the central upland ridge, and along the western side of the seepage slope community at the base of the central upland ridge are especially dense and, during the present stud y, were observed to be nearing succession into more of a hardwood community (Figure 8). The sub-canopy and herbaceous layer in the sections of ecotone with more closed upper canopies are generally sparse with few shrubs and herbaceous species amongst patches of moss and sand whereas the sub-canopy and herb aceous layer densities are variable in sections with more open upper ca nopies. The upper, mid, and sub-canopies of the vegetative structure in the patches of wet flat woods, found in the lower lying elevations and shallow depressions within the mesic and scrubb y flatwoods, are mostly open with a sparse herbaceous layer amongst open patches of sand.
A. B. Figure 16. Wet flatwoods in the University of South Florida Ecological Research Area. A. Wet flatwoods ecotone northeast of east gate. B. Imbedded patch of the community within the scrubby flatwoods. (Photographs courtesy of Jack Stites). 52
53 Pinus elliottii is the most dominant pine species in the upper canopy of the wet flatwoods community type. Sabal palmetto occurs in the upper canopy throughout. Acer rubrum Quercus laurifolia and Taxodium distichum appear in the upper canopy in the wetland edges of the ecotone and occasionally throughout. Pinus palustris Quercus geminata and Quercus virginiana are included in the upper canopies in the upla nd edges of the ecotone and the edges of the imbedded patches of wet flatwoods within the mesic and scrubby flatwoods. Myrica cerifera occurs at the edges of and occasiona lly throughout the mid-story of the ecotone. Vaccinium arboreum occurs in the mid-story on the upland side of the ecotone. It is also found on the periphery of the imbedded pa tches of the community within the mesic and scrubby flatwoods, along with an occasional occurrence of M. cerifera Diospyrus virginiana is occasionally found in the mid-story of the ecotone surrounding Buck Island. The sub-canopy on the wetland side of the ecotone includes Sideroxylon reclinatum Viburnum obovatum and, in a few places, Vaccinium corymbosum Lyonia ferruginea Lyonia fruticosa Serenoa repens and Vaccinium myrsinites are frequently found in the upland edges of the ecotone and on the periphery of the community type within the mesic and scrubby flatwoods. Ilex glabra is occasionally locally common in some areas of wet flatwoods, notably along the southern road through the camping area. Campsis radicans Gelsemium sempervirens, Toxicodendron radicans Vitis rotundifolia and Vitis shuttleworthii are vines that only occur where the upper canopies of the ecotone are more closed. Tillandsia setacea and Tillandsia simulata are epiphytes found in the denser upper canopies whereas Tillandsia recurvata and Tillandsia usneoides occur occasionally throughout. Grasses, sedges and rushes found throughout the herbaceous layer include Andropogon glomeratus var. glaucopis Andropogon virginicus var. glaucus Bulbostylis ciliatifolia Fimbristylis caroliniana, Juncus marginatus Juncus scirpoides Panicum hemitomon Panicum virgatum Rhynchospora fascicularis Rhynchospora globularis and Rhynchospora pusilla
54 Dichanthelium ensifolium var. unciphylum Dichanthelium leucothrix Dichanthelium strigosum var. glabrescens and Eustachys glauca are generally found in the ecotone, especially in the denser canopied areas. There is an extensive patch of Stenotaphrum secundatum that has taken over most of the wet flatwoods ecotone west of the seepage slope community that runs north to south along the western base of the central upland ridge. Hypericum gentianoides is a suffrutescent plant species that is most often found in the open wet flatwoods depressions and low lying areas within the pine flatwoods matrix. Other suffrutescent species include Hypericum hypericoides found on the wetland edges of the ecotone and occasionally within, and Hypericum tetrapetalum which occurs occasionally throughout the community type. Forbs that occur throughout the wet flatwoods community type include Lachnocaulon anceps Polygala lutea Polypremum procumbens Pterocaulon pycnostachyum Xyris caroliniana Xyris elliottii and Xyris jupicai Carnivorous plants that also occur throughout include Drosera capillaries, Pinguicula pumila, and Utricularia subulata. Forbs occasionally found in the herbaceous layer of the ecotone include Agalinis fasciculata Aslcepias longifolia Cirsium nuttallii Coreopsis leavenworthii Eupatorium leptophyllum, Helenium flexuosum Hypoxis curtissii Hypoxis wrightii Lacnanthes caroliana Linum medium Lobelia glandulosa Ludwigia suffruticosa Packera glabella Phyla nodiflora Pluchea rosea Polygala cruciata Rhexia mariana Sabatia grandiflora Syngonanthus flavidulus Teucrium canadense Trichostema dichotomum and Viola lanceolata Dichondra caroliniensis Erechtites hieraciifolius Oldenlandia uniflora, and Veronica peregrina occur in denser canopied sections of the ecotone. Polygala rugelii a Florida endemic, is abundant in the southeast section of the ecotone north of the east gate. The section of th e ecotone that runs along the eastern edge of the central upland ridge is one of the few places the terrestrial orchid, Calopogon tuberosus is found.
55 Open patches of wet flatwoods, found within the mesic and scrubby flatwoods communities, include Polygala nana and Sabatia brevifolia The wet flatwoods community is easily compromised by anthropogenic perturbations (Abrahamson and Hartnett 1990; FNAI and DNR 1990) During the present study, an old, raised dirt road was found running through the wet flat woods ecotone along the floodplain swamp edge, west of the seepage slope community at the b ase of the central upland ridge (Figure 8). The ecotone in the above area is littered with larg e pieces of concrete and pavement which may, possibly, have been the source of the extensive patch of Stenotaphrum secundatum mentioned above. As with the other palustrine communiti es that abut the floodplain swamp, the wet flatwoods community in the ecotone is particularly vulnerable to the unnatural cycles of drawdowns and flood events caused by the an thropogenically altered hydroperiod of the blackwater streams. Despite occurring in the lower elevations of the fire-dependent pine flatwoods matrix, the wet flatwoods community is a pyrogenic plant community that requires periodic fire to maintain the integrity of its fire dependent ecosystem (A brahamson and Hartnett 1990; FNAI and DNR 1990; Meyers 2000). During the present study, lack of the necessary fire frequency was observed to be evident in the densities of the upper canopies in the vegetative structure of the community in most of the ecotone and in the crowding out of the community type within the mesic and scrubby flatwoods. Terrestrial Communities The terrestrial communities, comprised of the mesic flatwoods, scrubby flatwoods, sandhill, and xeric hammock community types, occur in the upland areas of the USF Eco Area. Topography, soil composition, and fire frequency ar e among the key factors that differentiate the four community types. Mesic flatwoods, occurring on relatively flat terrain, and scrubby
56 flatwoods, on slightly higher elevations, are inte rmixed within the pine flatwoods matrix that includes the wet flatwoods community type. Terrain with more relief, in the higher elevations of the USF Eco Area, is comprised of the sandhill and xeric hammock communities. The xeric hammock is typically a climax community composed of relict sandhill or sand pine scrub vegetation, depending on the origin of the community. Mesic Flatwoods The mesic flatwoods community type, covering approximately 23 ha (57 a) or 8% of the USF Eco Area, occurs on broad, nearly level terrain that gradually slopes down into the wet flatwoods ecotone from the rest of the upla nd plant communities (Table 6) (Figures 8, 9. 17A). It is the most extensive ecosystem found in Florida and is the primary flatwoods community type within the fire-dependant, open-canopied, pine flatwoods matrix that characteristically includes a mosaic of small imbe dded islands of wet flatwoods in lower lying elevations and depressions; dome swamps and si nkholes where dissolution of the underlying limestone has occurred; and scrubby flatwoods on elevated rises within the community (Abrahamson and Hartnett 1990; FNAI and DNR 1990; Meyers 2000). The imbedded islands of wet flatwoods, sinkholes, and dome swamps were not mapped separately because of their relatively small sizes. The wet flatwoods community that primarily makes up the ecotone between the palustrine and terrestrial commun ities, and the scrubby flatwoods community type were large enough to warrant mapping. Slight variations in topography and edaphi c conditions play an influential role in the complex mosaic of differences in the hydrology, vegetative structure, and species composition between the three flatwoods communities, dome swamps, and sinkholes within the pine flatwoods matrix (Abrahamson and Hartnett 1990; Doolittle et al 1989; FNAI and DNR 1990; Meyers 2000). The mesic flatwoods community occurs on relatively flat terrain where the soils are moderately drained. The soils are composed of nutrient poor acidic sands, primarily Myakka fine sand, that
A. B. Figure 17. University of South Florida Ecological Research Area mesic flatwoods. A. More open canopied section of the mesic Flatwoods. B. The small sinkhole at the northern end of the community. (Photographs courtesy of Jack Stites). 57
58 include a lower percentage of clay in the soil horizons and an insignificant underlying layer of impermeable hardpan and clay as compared to th e wet flatwoods community type. Although the community is rarely inundated, it can become pe riodically saturated during the rainy season. The characteristically open canopies and sandy soils pr oduce generally droughty conditions during the dry season. Most of the species composition within the community is pyrophytic, adapted to and highly dependant on a fire frequency of every 2 years. The vegetative structure of the mesic flatwoods community type is typically open as it stretches across vast tracts of flat terrain. It includes an open upper canopy of widely spaced pine trees; a sparse mid-canopy with a few widely sca ttered cabbage palms; a variable sub-canopy, composed of saw palmetto and primarily ericace ous shrub species, that can range from being very open, low, and diverse to dense with extensive monotypic stands of saw palmetto; and a variable herbaceous layer composed of grasses and forbs that can range from being sparse and open to densely carpeted. The varying densities of the ve getative structural layers as well as the species composition and diversity are dictated by fire frequency and disturbance history (Abrahamson and Hartnett 1990; Doolittle 1989; FNAI and DNR 1990; Meyers 2000). Two small notable sinkholes punctuate the mesic flatwoods community in the USF Eco Area. A very small, circular sinkhole with steeply slope d sides occurs in the northern section of the community (Figure 17B) and a slightly larger sinkhole, more oval in shape with moderately sloped sides, occurs on the south side of the southern dirt road through the camping area. Sinkholes are typically cylindrical and conical depressions in the ground that have been formed by the dissolution and collapse of the underl ying limestone layer (Abrahamson and Hartnett 1990; Doolittle 1989; FNAI and DNR 1990; Meyers 2000). The soils covering the bottom and sides of the USF Eco Area sinkholes are essentially the same acidic sands found in the surrounding mesic flatwoods. Although inundate d with water for only short periods after extended heavy rain events, the sinkholes can remain saturated throughout the rainy season.
59 Rainwater and run-off from the surrounding comm unity are the main water sources. The water table, when it is higher during the rainy season, may also contribute to the hydrology of the sinkholes where the accumulated sands and debris have not completely occluded the connection to the groundwater. The vegetative structure of the USF Eco Area sinkholes is primarily a herbaceous layer that is mostly compo sed of wet flatwoods vegetation such as Bulbostylis ciliatifolia, Drosera capillaris Eleocharis vivipera Lachnocaulon anceps and Utricularia subulata One Cephalanthus occidentalis makes up the sub-canopy in the small, circular sinkhole in the northern section. There are two dome swamps imbedded with in the USF Eco Area mesic flatwoods community (see the hydric hammock community type section for dome swamp characteristics). A very small and shallow dome swamp, that includes a few Taxodium distichum and very little else, occurs on the north side of the southern road through the camping area. A larger dome swamp, that includes Taxodium distichum Osmunda regalis var. spectailis and Saururus cernuus as well as occasionally Celtis laevigata Sambucus nigra and Habenaria floribunda on the periphery, occurs east of the east gate on the south side of the main east-west dirt road through the USF Eco Area. The larger dome swamp is the only place in the USF Eco Area where Lygodium japonicum and Melaleuca quinquenervia are found, two FLEPPC Category 1 invasive exotic plant species. The mesic flatwoods community in the USF Eco Area has a variable vegetative structure throughout that is generally more closed in th e upper and mid-canopies than the typical vegetative structure of the community type except for the north central a nd northeast sections and along the west side of the central upland ridge sections wh ere it is more open. In the denser areas, the vegetative structure includes an upper canopy of a few scattered Pinus spp with a dominance of Quercus spp .; a mid-canopy primarily composed of Myrica cerifera ; a fairly dense sub-canopy of primarily tall Lyonia spp.; and a sparse herbaceous layer of primarily forbs with few grass species in small, open patches of sand amongst a scattering of Cladonia spp and moss. The north central
60 and northeast sections of the mesic flatwoods are more open and savanna-like with very widely spaced Pinus palustris Pinus elliiottii, and Sabal palmetto in the upper and mid-canopies; a dense, monotypic sub-canopy of Serenoa repens ; and a very thin herbaceous layer of forbs in the few small openings within the dense stand of S. repens The more open section of the community along the west side of the central upland ridge is variable and diverse in species composition in the sub-canopy and herbaceous layer. The upper canopy of the mesic flatwoods includes Pinus elliottii Pinus palustris Quercus geminata Quercus virginiana and Sabal palmetto Pinus taeda is only found in the upper canopy in the section of mesic flatwoods just north of the southwestern section of sandhill community and west of where the seepage slope turn s west at the southern end of the community (Figure 8). There are several infrequent occurrences of Ilex opaca in the mid-canopy of the community. A fairly large I. opaca occurs just east of the small sinkhole in the northern section of the community. Myrica cerifera and Vaccinium arboreum frequently occur throughout the mid-canopy while Rhus copallinum is only found occasionally th roughout. The mid-canopy in the mid-southeast section of the community, just north and east of the east gate, includes a small population of Chionanthus virginicus Serenoa repens frequently occurs throughout the sub-canopy while Callicarpa americana Gaylussacia dumosa Vaccinium darrowii and Vaccinium myrsinites occur only occasionally throughout. Lyonia ferruginia, Lyonia fruticosa, and Vaccinium stamineum are more frequent in the denser sections of the community. Ilex glabra is more often found in the southern section of the campground. Interestingly, Lyonia lucida typically found in the sub-canopy of the mesic flatwoods community type, rarely occurs in the USF Eco Area. Vines such as Campsis radicans Gelsemium sempervirens Parthenocissus quincuefolia Smilax auriculata and Vitis rotundifolia occur in the denser canopied mesic flatwoods sections.
61 Epiphytes include Tillandsia recurvata Tillandsia simulata Tillandsia usenoides and Tillandsia x floridana The pteridophyte, Pteridium aquilinum occurs occasionally throughout the community. Grasses include Andropogon gyrans, Aristida pupura scens, Dichanthelium leucothrix and Dichanthelium portoricense. Suffrutescent species include Asimina reticulata, a Florida endemic, and Lechea minor a new record for Hillsborough County. Balduina angustifolia Chamaecrista fasciculata Dalea pinnata, Euthamia caroliniana Galactia volubilis Gratiola hispida Helianthemum corymbosum Hypericum tetrapetalum, Piloblephis rigida Piriqueta cistoides Pityopsis graminifolia Polygonella polygama, Pterocaulon pynchostachyum Sericocarpus tortifolius Stipulicida setacea var. lacerata and Symphyotrichum dumosum are among the forbs that are scattered throughout the herbaceous layer of the mesic flatwoods. During the present study, absence of the necessary fire frequency, essential for maintaining the fire-adapted and fire-dependant ecosystem of the mesic flatwoods, was observed in the closed, hardwood dominated upper canopies; the density of the extensive Serenoa repens stands in the north central and northeastern sections; and the sparse herbaceous layer throughout that revealed a paucity of grasses and low forb diversity. Th e difference between the closed canopied sections, where fire has not been through the area for over 20 years, and the more open canopied section of the community, where a fire had gone through the area within the last 10-15 years, illustrates the importance of periodic fire in restricting the invasion of hardwood tree species in the upper canopies of the community. Close proximity to Fletcher Avenue may be one of the contributing factors that might explain the concentration of FLEPPC Category I invasive exotic plant species in the larger dome swamp in the section of mesic flatwoods east of the east ga te, on the south side of the main east-west dirt
road through the USF Eco Area. If not checked, there is potential for the invasive species to spread into the rest of the USF Eco Area which, fortunately, has not occurred as of yet. Scrubby FlatwoodsThe scrubby flatwoods community type, covering approximately 4 ha (10 a) or 1% of the USF Eco Area, occurs in three separate areas on the slightly higher elevations within the open canopied, fire-dependent, pine flatwoods matrix that includes the wet and mesic flatwoods community types (Table 6) (Figures 8, 9, 18). The largest area, covering Figure 18. Scrubby flatwoods in the University of South Florida Ecological Research Area. approximately 2 ha (4 a), occurs northwest of the central upland ridge that dips north into the floodplain swamp, where it has an approximate slope of 2% that grades down into wet and 62
63 mesic flatwoods from an approximate elevation of 10 m (31 ft) above msl (Figure 8). An area of scrubby flatwoods, covering 1 ha (3 a), occurs at the northern end of the central upland ridge where it grades down into mesic flatwoods with an approximate slope of 2% from an approximate elevation of 11 m (37 ft) above ms l and abuts xeric hammock to the south (Figure 8). In the southeastern portion, west of Riverfront Park, another area of the community, covering 1 ha (3 a), grades down into mesic flatwoods and a small area of floodplain forest to the east with an approximate slope of 34% from an approximate elevation of 11 m (35 ft) above msl (Figure 8). As mentioned previously, the differences in hydrology, vegetative structure, and species composition between the wet, mesic, and scrubby flatwoods community types are strongly influenced by subtle changes in topography and edaphic conditions (Abrahamson and Hartnett 1990; Doolittle et al. 1989; FNAI and DNR 1990; Meyers 2000). The scrubby flatwoods community is found on the rises and ridges in the higher elevations of the pine flatwoods matrix where the soils are moderately to very well draine d. Soils are mostly composed of, nutrient poor, deep acidic sands, primarily Pomello fine sand, that have a minimal percentage of clay in the soil horizons and a very insignificant, if any, underl ying impermeable layer of hardpan or clay as compared to the wet and mesic flatwoods commun ities. Although the water table is not much lower than that of the wet and mesic flatwoods, the pomello sands in the scrubby flatwoods never become inundated, even during extended heavy rains. Felda fine sand, not as well drained as Pomello fine sand, occurs in the slightly less sl oped terrain of the scrubby flatwoods northwest of the central upland ridge. It is also composed of nutrient poor, acidic sands but includes a higher percentage of clay in the soil horizons with a fairly significant underlying impermeable layer of hardpan or clay. The area with Felda fine sa nd may become periodically saturated during the rainy season but is rarely inundated except in lower lying areas where it may become inundated
64 for only short periods after heavy rain events. Scrubby flatwoods, with both soil types, can become extremely droughty during the dry season. In the map of the USF Eco Area that includes the 1989 USDA/SCS Soil Survey of Hillsborough County, only the scrubby flatwoods in the southeastern portion, west of Riverfront Park, was mapped as Pomello fine sand whereas the scrubby flatwoods northwest of the central upland ridge and the section of scrubby flatwoods at the northern end of the central upland ridge were mapped as Felda fine sand and Myyaka fine sand, respectively (Figures 6, 8). During the present study, the topography, edaphic characteristics, vegetative structure, and species composition in the more sloped terrain of the co mmunity northwest of the central upland ridge and the entire section of the community at the northern end of the central upland ridge were observed to be remarkably similar in all r espects to the southeastern portion mapped by the USDA/SCS in 1989 as Pomello fine sand (Figures 6, 8). Based on the stated qualitative observations, it was conjectured that the two areas of scrubby flatwoods, noted above, are composed of Pomello fine sand. Site specific c onfirmation of the soil type, done on a larger scale than used by the USDA/SCS in 1989, is recomme nded as soil sampling is out of the scope of the present study. The scrubby flatwoods community type in cludes much species overlap, as it generally makes up the ecotone that grades from mesic flatwoods into the more upland communities of sandhill and scrub (Abrahamson and Hartnett 1990; FNAI and DNR 1990; Meyers 2000). The vegetative structure of scrubby flatwoods typically includes an upper canopy that can be either open with widely scattered pines and cabbage palms or dense with primarily xerophytic oak tree species; a moderate to dense mid and sub-canopy of low, shrubby, xerophytic trees and shrubs; and a sparse herbaceous layer with open patches of sand. Despite being an integral part of the pyrogenic pine flatwoods matrix, the vegetative structure and sp ecies composition is not as conducive to frequent fire as those of the wet and mesic flatwoods co mmunities. Fire may occur every decade or so
65 when the weather has been extremely dry for an extended period and enough leaf litter has accumulated to carry fire through the community. In the USF Eco Area, the vegetative structure of the scrubby flatwoods community is mostly on the denser side of the typical vegetative stru cture. The denser upper, mid, and sub-canopies include a sparse herbaceous layer composed of grasses, sedges, and very few forbs amongst scattered lichens ( Cladonia spp .) and mosses in patches of sand. The higher elevations of the scrubby flatwoods northwest of the central upland ridge, the western portion of the community at the northern end of the central upland ridge, a nd the entire southeastern section of the community are especially dense with a monotypic upper canopy of Quercus geminata and a densely compacted sub-canopy of tall Lyonia ferruginea and Serenoa repens The slightly less sloped areas, to the south and southeast, in the section of the community northwest of the central upland ridge as well as the eastern portion of the community at the northern end of the central upland ridge include a more open and diverse vege tative structure with a few widely spaced Pinus spp. Quercus spp., and Sabal palmetto in the upper canopy; a sparse mid-canopy of widely scattered Vaccinium arboreum ; a fairly dense sub-canopy of S. repens with a few widely scattered L. ferruginea ; and a moderately sparse herbaceous layer of primarily forbs, mosses, and Cladonia spp in the few sandy openings within the stand of S. repens The upper canopy of the USF Eco Area scrubby flatwoods includes Pinus elliottii Pinus palustris Quercus geminata, Quercus virginiana Quercus laurifolia and Sabal palmetto. P. elliottii and Q. laurifolia generally occur in the slightly l ess sloped areas of the community. In the mid-canopy, Vaccinium arboreum is frequently found where the upper canopy is not as dense. Myrica cerifera Rhus copallinum and the low, shrubby, xerophytic tree species Quercus chapmanii and Quercus myrtifolia occur occasionally throughout the mid-canopy. Serenoa repens and tall Lyonia ferruginea are ubiquitous throughout the sub-canopy of the community, especially in the more closed upper canopies dominated by Q. geminata The sub-canopy also
66 occasionally includes Asimina reticulata, Bejaria racemosa Gaylussacia dumosa Lyonia fruticosa Vaccinium darrowii Vaccinium myrsinites and Vaccinium stamineum Interestingly, B. racemosa typically an occasional component in pine flatwoods, only occurs in the USF Eco Area in a small but robust patch in the western portion of the community at the northern end of the central upland ridge Gelsemium sempervirens and Smilax auriculata are vines that occasionally occur in the community. Pleopeltis polypodioides var. michauxiana Tillandsia recurvata Tillandsia simulata Tillandsia usenoides and Tillandsia x floridana are epiphytes that occasionally occur throughout as well. The pteridophyte, Pteridium aquilinum has a variable distribution throughout. Andropogon gyrans and Aristida pupurascens are among the few grasses that occur in the USF Eco Area scrubby flatwoods. Suffrutescent species include Lechea minor and Seymeria pectinata L. minor is generally found in open patches of sand and is a new record for Hillsborough County. Euthamia caroliniana Gratiola hispida Piloblephis rigida Polygala nana Pterocaulon pycnostachyum Sericocarpus tortifolius and Stipulicida setacea var. lacerata are the more dominant forbs found in the herbaceous layer throughout the USF Eco Area scrubby flatwoods. Fire is long overdue in the denser are as of the scrubby flatwoods community in the USF Eco Area, where the diversity of species compositi on has succumbed to a densely monotypic upper canopy of Q. geminata and a dense sub-canopy of L. ferruginea and S. repens Otherwise, little disturbance was found in the community during the present study. SandhillThe sandhill community type was described by S.W. Greene in 1931 as The Forest that Fire Made and The Forest that Fire Protects (Greene 1931). It is an open-canopied, xeric, highly pyrogenic pineland, dominated by longleaf pi nes, that occurs on deep, marine deposited
Figure 19. University of South Florida Ecological Research Area sandhill plant community. (Photograph courtesy of Kai Rains). sands of very dry, sandy ridges, ridge tops, and rolling hills that were once Plio-Pleistocene beach ridges, sand dunes, and bars (Doolittle et al. 1989; FNAI and DNR 1990; Meyers 1990, 2000). In the past, it had been a prevalent natural community type throughout most of Florida, but has now 67
been reduced to the point where it is globally and Florida State listed as threatened and endangered (FNAI/Abbey 2004). Although relatively small, the sandhill community in the USF Eco Area is one of the few remaining tracts left in Florida. 1ECE7E2ECW1W5EC2E7W5W2WC2W Covering approximately 13 ha (31 a) or 4% of the USF Eco Area, it is found on the undulating, hillier terrain at the highest elevations in the south central portion where it primarily grades down into mesic flatwoods to the north with approximate slopes of 4% from elevations of approximately 1218 (40 ft) above msl, except at the northern tip, where it grades into xeric hammock (Table 6) (Figures 8, 9, 19). The sandhill community in the USF Eco Area is managed by controlled burning, a vital land management tool for the maintenance and preservation of the disappearing community type. For research and educational purposes, several experimental burn plots have been delineated to monitor and study the ecological responses and consequences of differing fire frequencies in the fire prone ecosystem (Figure 20) (Appendix B). Figure 20. Experimental burn plots in the University of South Florida Ecological Research Area. Numbers refer to scheduled prescribed burn rotation: every 1 year, 2 years, 5 years, and 7 years. C Control (unburned); E East; W West. 68
69 The vegetative structure of the sandhill comm unity type is primarily composed of deep-rooted, xerophytic, and pryrogenic vegetation. It ty pically includes a high, open upper canopy of scattered longleaf pines; a minimal mid and subcanopy of deciduous oak species, predominately turkey oak; and a herbaceous layer dominated by grasses with wiry morphology interspersed with an abundance of scattered forbs, primarily composed of aster and legume species. Fire frequency and intensity play an influential role in the de nsities of the vegetative structural layers as well as the species composition and diversity (Doolittle et al. 1989; FNAI and DNR 1990; Meyers 1990, 2000). Soils in the sandhill are excessively well drained and are composed of very deep, infertile, gray to yellowish, loose sands, primarily Candler fine sand in the USF Eco Area, with little to no horizon development (Doolittle et al. 1989; FNAI and DNR 1990; Meyers 1990, 2000). The rapid permeability and low available water capacity of the porous sands results in minimal run-off and evaporation, making the community a prime aquifer recharge area. The same characteristics also lead to the rapid leaching of plant nutrien ts. Nutrients are periodically replaced by the frequent fires and burrowing fauna associated with the community. The open canopy, deep sandy soils, along with a seasonal high water table depth of more than approximately 2 m (7 ft), produce droughty conditions throughout the year particularly in the dry season. Fire is a natural and extremely important eco logical force that has shap ed the ecosystem of the sandhill community type. The sandhill is character ized as a fire climax community where low intensity ground fires, with frequencies of every 1 years, particularly every 2 years, are essential for maintaining the highly fire-adapted and fire-dependent ecosystem (Doolittle et al. 1989; FNAI and DNR 1990; Meyers 1990, 2000). Many of the species associated with the fire prone community require fire for their continual survival and perp etuation. They have evolved adaptations that not only enable them to with stand frequent fires but to also facilitate the movement of fire throughout the community. Wi thout fire, the community eventually becomes a
70 hardwood dominated, xeric hammock from the inv asion of non-pyrogenic, hardwood species that close the upper canopies thereby compromise the regeneration of the longleaf pines and sandhill grasses as well as the other open-canopied depende nt, pyrogenic species associated with the community. As mentioned earlier, the sandhill community in the USF Eco Area has been broken up into experimental burn plots that include two plots fo r each fire frequency regime of every one, two, five, and seven years and four unburned control plots (Figure 20) (Appendix B). The average size of each plot is approximately 1 ha (3 a). With some exceptions, the two plots with the same fire frequency, as well as the four unburned control plots, do not abut each other. The different regimes of fire frequency in each of the experimental burn plots and the unburned control plots have produced a variable vegetative structure throughout the community in the USF Eco Area. In the areas with higher fi re frequencies, the vegetative structure includes a fairly open upper canopy, primar ily composed of widely spaced Pinus palustris ; sparse mid and sub-canopies composed of a few scattered deciduous Quercus tree species and ericaceous shrubs; and a fairly dense herbaceous groundcover. As the fire frequency is reduced per experimental burn plot, the vegetative structure in the upper, mid, and sub-canopies becomes denser with an ever increasing dominance of the non-pyrogenic, persistent leaved Quercus geminata and an increasing abundance of Quercus laevis and Quercus incana as well as other variable tree and shrub species. The increasingly denser canopies, in turn, include an increasingly sparse and less diverse herbaceous groundcover. Pinus palustris is the dominant upper canopy tree species in the more frequently burned areas. Quercus geminata increasingly becomes codominate with the P. palustris in the upper canopy as fire frequencies decrease where it occurs as scattered large individuals and/or in clonal clumps of ramets that periodically form dense oak domes. Pinus elliottii infrequently occurs in the upper
71 canopy in the lower elevations of the sandhill, abutting the mesic flatwoods. Sabal palmetto occurs occasionally throughout. The predominant and ubiquitous deciduous oak species throughout the mid-canopy of the community is Quercus laevis which is sparsely scattered throughout the frequently burned areas and abundant in the areas less frequently burned. Quercus incana a deciduous to semi-deciduous oak species, is sparsely scattered throughout the burned areas but increasingly becomes a codominant with Q. laevis in areas with less fire frequency. The mid-canopy includes an occasional occurrence of Quercus chapmanii and Quercus myrtifolia in the less frequently burned areas. Diospyrus virginiana and Vaccinium arboretum occur only occasionally in areas with higher fire frequencies but become increasingly more abundant as fire frequencies decrease. Crataegus michauxii Prunus umbellata, Rhus copallinum Sideroxylon tenax are other mid-canopy species that occasionally occur throughout the less often burned and unburned areas. Prunus serotina occasionally occurs in the unburned areas throughout and Zanthoxylum clava-herculis occurs in the unburned areas near the chain link fence on the south side of sandhill that runs along Fletcher Avenue. Vaccinium darrowii Vaccinium myrsinites and Vaccinium stamineum become more abundant throughout the sub-canopy as the fire frequency drops. Asimina pygmea Asimina reticulata, Licania michauxii Serenoa repens Yucca filamentosa occur occasionally throughout the subcanopy of the community. Very few vines and epiphytes o ccur in the sandhill. Vines that include Smilax auriculata and Vitis aestivalis are most often found in the denser canopied, unburned areas. Tillandsia recurvata and Tillandsia usenoides are among the few epiphytes that occur occasionally throughout, more often in the less frequently burned and unburned areas. The pteridophyte, Pteridium aquilinum is only occasionally found on the edges of unb urned areas abutting the mesic flatwoods.
72 Aristida stricta var. beyrichiana and Sporobolus junceus are grasses with wiry morphology that dominate the herbaceous groundcover in th e sandhill. Strikingly colorful grasses such as Eragrostis elliottii and Sorghastrum secundum are abundant in the more frequently burned areas. Other grasses, occasionally occurring throughout, include Anthaenantia villosa Andropogon ternarius Andropogon tracyi Aristida purpurascens Cenchrus gracillimus Dichanthelium ovale Dichanthelium portoricense, Eustachys neglecta Eustachys petraea Panicum anceps Paspalum setaceum Setaria parviflora and Triplasis americana Sedges that are also occasionally found throughout the community include Bulbostylis ciliatifolia Bulbostylis stenophylla Bulbostylis warei, Cyperus croceus Cyperus filiculmis, Cyperus retrorsus and Rhynchospora grayi The frequently burned areas include an abundance of suffrutescent and forb species, dominated by the Asteraceae and Fabaceae plant families, that decrease as the canopies become increasingly denser in the less frequently burned and unburned areas. Species from the Asteraceae include a frequent occurrence of Balduina angustifolia Carphephorus corymbosus Pityopsis graminifolia and Liatris species such as Liatris gracilis Liatris pauciflora Liatris tenuifolia and Liatris tenuifolia var. quadriflora Asters with an occasional occurrence throughout include Ageratina jucunda, Chrysopsis scabrella Elephantopus elatus Eupatorium compositifolium Euthamia caroliniana Palafoxia integrifolia Sericocarpus tortifolius Solidago stricta and Symphyotrichum concolor The asters Hiercium gronovii, Hieracium megacephalo n, and Symphyotrichum dumosum are less often found in the community in the USF Eco Area. Arnoglossum floridanum Berlandiera subacaulis and Phoebanthus grandiflorus are endemic asters that occur throughout. Fab aceae suffrutescent and forb species include Baptisia lecontei Chamaecrista fasciculata, Clitoria mariana Crotalaria rotundifolia Desmodium floridanum Dalea carnea Dalea pinnata Galactia volubilis Lespedeza hirta Lupinus diffuses, Mimosa
73 quadrivalvis var. angustata, Rhynchosia michauxii Rhynchosia reniformis and Tephrosia chrysophylla Other suffrutescent and forb species found throughout the community include Asclepias humistrata Asclepias tuberosa Asclepias verticillata Cnidoscolus stimulosus Croton argyranththemus Croton michauxii Dyschoristes obllongifolia, Eriogonum tomentosum Froelichia floridana Helianthemum corymbosum Houstonia procumbens a record occurrence for Hillsborough County of Lechea minor Lechea sessiliflora Onosmodium virginianum Opuntia humifusa Piriqueta cistoides Polygala violacea Polygonella gracilis Ruellia caroliniensis Ruellia ciliosa the endemic Scutellalria arenicola, Stillingia sylvatica, Tragia urens and Viola palmata Aureolaria pedicularia var. pectinata, Seymeria pectinata and Krameria lanceolata are included among the semi-parasitic sp ecies that are periodically found in the sandhill. Trailing, vine-like forbs, included in the herbaceous groundcover, are Stylisma patens and the Florida endangered Matelea pubiflora (Coile and Garland 2003). The 1938 USDA/SCS Hillsborough County Soil Survey aerial photograph shows that, historically, the sandhill community type was quite extensive throughout the surrounding area, especially to the south (Figure 4). As a prime, pine dominated upland; it has been usurped and irreversibly altered by development, agriculture silvaculture, fragmentation, and fire suppression throughout the years (Doolittle et al. 1989; F NAI and DNR 1990; Meyers 1990, 2000). At various times in the past, the community in the USF Eco Area has been used as a home site, pastureland, turpentine extraction site, and dumping ground. Close proximity to Fletcher Avenue makes the community vulnerable to the potential invasion of exotic species, trash, lights, and noise. The sandhill in the USF Eco Area is also compromised by the current, extremely cautious, climate of prescribed burning in urban areas that, in turn, prevents consistency in the burn regimes needed to properly maintain it as well as maintain the proper timeliness of the varying burn regimes within the experimental burn plots. Despite the overwhelming anthropogenic
74 intrusions listed above and the communitys relatively small si ze, the remnant of endangered sandhill community type and its ecosystem, found in the USF Eco Area, has remarkably survived and somewhat maintained an essence of its integrit y and viability, so much so, that it still remains an extremely valuable resource to the University of South Florida for research and education in the study of endangered habitats and the species of special concern within them. Xeric Hammock The pyrogenic, open canopied, upland communities of scrub, sand pine scrub, and sandhill, that occur on the deep sands of ridges and undulating hills, typically senesce into the xeric hammock community type in their advanced stages of succession (Doolittle et al. 1989; FNAI and DNR 1990; Meyers 1990, 2000). Xeric hammock often occurs in isolated patches where fire has been prevented from running thr ough the above communities for at least 30 years or more by natural fire barriers such as rivers, swamps, or non-pyrogenic communities; anthropogenic fragmentation; or fire suppression. In their senescence, the typically open upper canopies of the above communities become denser with the invasion of non-pyrophytic, hardwood climax vegetation thereby diminishing th e herbaceous layer as well as the diversity of the original communities. Remnant vegetative structure and species composition, derived from the original communities, typically creates vari ation in the overall appearance of the xeric hammock community type. In the 1938 USDA/SCS Hillsborough County Soil Survey aerial photograph, the two areas of xeric hammock community type, in total covering approximately 7 ha (17 a) or 2% of the USF Eco Area, are shown to have historically b een sand pine scrub and sandhill communities with primarily open upper canopies (Table 6) (Figures 4, 8, 9, 21). The larger area of xeric hammock, covering approximately 5 ha (11 a), is a sen escent sand pine scrub community that occurs on Buck Island in the middle of the floodplain swamp, in the mid-western portion of the USF Eco Area (Figures 4, 8, 21A). With approximate slopes of 2% from elevations of approximately
A. B. Figure 21. Areas of xeric hammock plant community in the University of South Florida Ecological Research Area. A. Senescent sand pine scrub on Buck island. B. Senescent sandhill on the central upland ridge. 75
76 9 m (28 ft) above msl, it grades down into the wet flatwoods ecotone encircling the island. The smaller of the two areas, covering appr oximately 2 ha (6 a), is a senescent sandhill community that occurs on top of the central upland ridge that dips north into the floodplain swamp, (Figures 4, 8, 21B). At elevations of approximately 1112 m (36 ft) above msl, the smaller area of xeric hammock grades into scrubby flatwoods to the north, sandhill to the south, and down into mesic flatwoods to the west and east with approximate slopes of 2%. Primarily composed of xerophytic plant species, typical vegetative structure of the xeric hammock community type is variable in that it can range from a dense, low, and scrubby oak dominated forest in the upper and mid canopi es with relatively sparse shrub and herbaceous layers to a multi-storied hardwood dominated forest that may include densely to widely scattered pines in the upper canopy, fairly dense mid and sub-canopies, and a sparse herbaceous layer (Doolittle et al. 1989; FNAI and DNR 1990; Meye rs 1990, 2000). Variation in the vegetative structural layers and species composition generally reflect the age of the xeric hammock and the original community types from which it was derived. Soil types differ between the two areas of xeric hammock in the USF Eco Area, based on the original community types (Doolittle et al. 1989) (Figure 6). Soils in the xeric hammock community on Buck Island exhibit the white-washed sands typically associated with sand pine scrub communities whereas the soils in the smaller area of xeric hammock on top of the central upland ridge are consistent with the characteris tic yellowish Candler fine sand of the sandhill community type (Figure 6). There is some ques tion as to the specificity of the mapped soil type on Buck Island that may be a symptom of the small scale used when mapping the 1989 USDA/SCS Soil Survey of Hillsborough County. All of Buck Island, including the ecotone into the swamp, was mapped as Immokalee fine sand wh ich is a poorly to moderately drained soil type that is more consistent with the periodi cally saturated pine flatwoods community type (Figure 6). During the present study, the topo graphy, edaphic characteristics, vegetative
77 structure, and species composition of the sand pine dominated upper portions of Buck Island were found to be inconsistent with Immokalee fine sand characteristics and its associated community traits. It is conjectured, based on the above qualitative observations, that the higher elevations, dominated by sand pine, may possibly be some other soil type that is more consistent with a sand pine scrub community. Site specific confirmation of the soil type, done on a larger scale than used by the USDA/SCS in 1989, is recommended, as soil sampling is out of the scope of the present study. Although the soil types of the origin al sand pine scrub and sandhill communities differ between the two areas, they have similar basic edaphic characteristics. Both soil types are excessively well drained and composed of very d eep, nutrient poor, mari ne deposited siliceous sands, with little to no horizon development, derived from Plio-Pleistocene beach ridges and dune systems (Doolittle et al. 1989; FNAI and DNR 1990; Meyers 1990, 2000). The deep porous sands and the characteristically deep seasonal high water table depths of the original community types produce droughty conditions throughout th e year, particularly during the dry season. Before senescence, both areas of xeric hammock in the USF Eco Area had originally been fire-maintained and fired dependent communiti es with differing fire frequency and intensity characteristics (sand pine scrubinfrequent, high intensity; sandhillfrequent, low intensity). The floodplain swamp around Buck Island; the close proximity of the less fire-prone communities on three sides of the smaller area of xeric hammock; and the north-south dirt road through the USF Eco Area, cutting part of the sm aller area of xeric hammock off from the more fire prone sandhill community to the south, ma y possibly be the contributing factors that prevented fire from having gone through the orig inal communities. The incombustibility of the climax vegetation in the xeric hammock areas a nd the density of the upper canopies diminishing the herbaceous groundcover to the point where it is unable to carry a fire, lower the prospects of fire going through the community even more. Chance ignitions, such as lightning hitting Buck
78 Island or from a fire going through the abutting san dhill community to the south of the smaller area of xeric hammock, may occur only if high winds and low humidity are combined with an extended period of extremely dry conditions and enough leaf litter has accumulated to carry fire through the community. Once a fire is ignited, it is typically a very hot and furious, catastrophic fire that, in turn, could potentially revert the xeric hammock back into its original community or into another community type altogether (D oolittle 1989; FNAI and DNR 1990; Meyers 1990, 2000) The two areas of xeric hammock in the USF Eco Area reflect the typical vegetative structure of the community type in their similarities and differences. They both have relatively closed upper canopies dominated by Quercus geminata a mix of persistent-leaved and/or deciduous hardwood tree species in the mid-canopies, vari able mid and sub-canopies, and relatively sparse herbaceous layers. The distinctive vegetative characteristics between the two separate areas of xeric hammock illustrates the variation that occu rs in the basic vegetative structure and species composition that reflects the original community type from which it was derived. The vegetative structure and species composition found on Buck Island is typical of a xeric hammock community that has developed from sa nd pine scrub. The upper canopy is dominated by Pinus clausa and a fairly dense population of somewhat stunted Quercus geminata that also includes a few, very widely scattered Pinus palustris The mid-canopy is composed of a diverse mix of scrubby Quercus species, Vaccinium arboreum and a few other hardwood species. Tall Lyonia ferruginea dominate the relatively dense sub-canopy. Herpothallon sp and many other lichens cover the trees and shrubs throughout the community. The groundcover in the herbaceous layer, that once included large open patches of white sand that may possibly have included the characteristic scattering of endemic and listed sp ecies, typical of isolated scrub and sand pine scrub communities, has primarily been taken over by mosses and several Cladonia species
79 amongst a paucity of grasses, sedges, and forbs as the senecense of the sand pine scrub community occurred over time. The vegetative structure of the small area of xeric hammock on top of the central upland ridge, derived from the sandhill community t ype, includes a dominance of large Quercus geminata with a scattering of a few Pinus palustris in the upper canopy. Quercus laevis and Quercus incana dominate the mid-canopy. The sub-canopy is sparse, primarily composed of scattered Serenoa repens Wiry grasses and very few forbs amongst Cladonia spp and patches of sand make up the sparse and discontinuous herbaceous layer. The upper canopies in both areas of xeri c hammock in the USF Eco Area are dominated by Quercus geminata A wide scattering of Pinus palustris and Sabal palmetto are also included throughout both upper canopies. Pinus clausa is a codominant with Q. geminata in the upper canopy of the community on Buck Island, many of wh ich are twisted, leaning, and/or have fallen. There is an occasional occurrence of Pinus elliottii Quercus laurifolia Quercus virginiana and even Quercus nigra in the lower to mid elevations of the community on Buck Island. Quercus chapmanii and Vaccinium arboreum occur throughout the mid-canopies of both areas. V. arboreum occurs quite frequently on Buck Isla nd, especially as the community slopes down the sides of the island, where it is more open. Other mixed hardwoods, found in the midcanopy of the community on Buck Is land, include occasional occurrences of Ilex ambigua and Persea borbonia var. humilis and a rare occurrence of Ximenia americana There is also a surprisingly, relatively large population of Chionanthus virginicus in the mid-canopy on Buck Island, where it occasionally occurs in locally co mmon groups throughout the higher elevations of the community. Quercus laevis and Quercus incana are abundant throughout the mid-canopy of the smaller area of xeric hammock on top of the central upland ridge. A wide scattering of Diospyros virginiana Quercus myrtifolia and Rhus copallinum are also included in the midcanopy of the smaller area.
80 Tall Lyonia ferruginea dominates the sub-canopy of the community on Buck Island whereas it only occasionally occurs throughout the sub-ca nopy of the smaller area of xeric hammock derived from sandhill. Serenoa repens and Vaccinium myrsinites are occasionally found throughout the sub-canopies of both areas. Asimina pygmea Asimina reticulata Licania michauxii, Lyonia fruticosa Vaccinium darrowii Vaccinium stamineum and Yucca filamentosa are widely scattered throughout the sub-canopy of the smaller area of the community. Vines, such as Gelsemium sempervirens Smilax auriculata Vitis aestivalis and Vitis rotundifolia have a variable distribution thro ughout both areas of xeric hammock. Tillandsia recurvata and Tillandsia usenoides are epiphytes that occasionally occur throughout both areas as well. Epiphytes such as Tillandsia setacea and the endemic Tillandsia simulata are found throughout the community on Buck Island. Very fe w pteridophytes occur in either of the areas of xeric hammock in the USF Eco Area, except for an occasional occurrence of Pteridium aquilinum primarily on the edges of the community. Dichanthelium ovale Dichanthelium portoricense, Scleria triglomerata and Rhynchospora megalocarpa are among the occasional grasses and sedges that occur in the herbaceous layer of the xeric hammock on Buck Island. Aristida stricta var. beyrichiana and Sporobolus junceus are the wiry grasses that dominate the herbaceous layer in the smaller area of the community. Helianthemum corymbosum is one of the very few forbs that occur in the herbaceous layer of the community on Buck Island. Balduina angustifolia Baptisia lecontei, Carphephorus corymbosus Cnidoscolus stimulosus Dalea pinnata Eriogonum tomentosum Eupatorium compositifolium Galactia volubilis Krameria lanceolata Liatris tenuifolia var. quadriflora Lupinus diffuses Polygala nana Stillingia sylvatica and Tephrosia chrysophylla are the few remnant forbs found in the herbaceous layer of the smaller area of the community derived from sandhill.
81 Despite several anthropogenic disturba nces, both areas of the USF Eco Area xeric hammock community have remained somewhat intact. The xeric hammock on Buck Island is riddled with dug out potholes from many years of archaeological and anthropological investigations into past inhabitation on the island. Prior to 1938, the middle of the smaller area of the community, on top of the upland central ridge, had been deeply excav ated in the process of building a logging road for access to the floodplain swamp to the north. Based on the 1989 USDA/SCS Hillsboroug h County Soil Survey aerial photograph and the general observations during the present study, both areas of xeric hammock in the USF Eco Area are conjectured to be in the younger stages of the community type. A series of carefully prescribed fire in both areas of the community may potentially revert them back to their original respective communities. Rural/DevelopedThe ruderal/developed plant community type is associated with areas in which native vegetation is continually disturbed anthrop ogenically, so much so that weedy pioneer and exotic plant species become the dominant vegetation. Approximately 61 ha (150 a) or 20% of the USF Eco Area is comprised of the ruderal/develope d plant community type (Table 6) (Figures 8, 9, 22). Ruderal areas in the USF Eco Area include dumping and storage sites, and areas along roads, fences, and firebreaks (Figure 22A). Developed areas include the USF Golf Course and Riverfront Park (Figures 22B, 22C). The ruderal areas were not mapped separately as a result of their relatively small sizes whereas the develope d areas were large enough to warrant mapping. Occasional upper, mid, and sub-canopy weedy species found in the USF Eco Area ruderal/developed community include Prunus serotina Salix caroliniana and Sambucus nigra. Fortunately, Schinus terebinthifolius a FLEPPC Category 1 invasive exotic plant species, occurs only rarely in the community.
A. B. C. Figure 22. Ruderal/developed plant community in the University of South Florida Ecological Research Area. A. Ruderal. B. USF Golf Course. C. Riverfront Park. 82
83 Common weedy grasses and sedges that occu r occasionally throughout the community include Axonopus furcatus Cenchrus gracillimus Cynodon dactylon Cyperus esculentus Dichanthelium ovale Dichantheliunm portoricense Echinochloa muricata, Eustachys glauca Eustachys petraea Paspalum notatum Paspalum setaceum Rhynchelytrum repens Setaria parviflora Stenotaphrum secundatum and Urochloa mutica Varieties of Cynodon dactylon are the dominant grasses planted on the USF Golf Course. Paspalum notatum is the dominant grass found around Riverfront Park. Occassional suffrutescent and herbaceous species included throughout the community are Acalypha gracilens Ambrosia artimisiifolia Bidens alba Commelina diffusa, Conyza canadensis var. pusilla Croton glandulosus Dichondra caroliniensis Eryngium baldwinii Erechtites hieraciifolius Erigeron quercifolius Eupatorium compositifolium Froelichia floridana Gomphrena serrata, Gaura angustifolia Linaria canadensis Lepidium virginicum Oxalis corniculata Phyla nodiflora Plantago virginica Portulaca oleracea Portulaca pilosa Richardia grandiflora Sida rhombifolia Solanum americanum Urena lobata Veronica peregrina, and Youngia japonica
84 ANNOTATED LIST OF THE VASCULAR FLORA The vascular flora of the University of South Florida Ecological Research Area (USF Eco Area) is documented by voucher specimens in th e USF Herbarium. The Annotated List of the Vascular Flora is organized alphabetically by family, genus, and species under the headings of Pteridophytes (Ferns and Fern Allies), Gym nosperms, Angiosperms (Monocotyledons), and Angiosperms (Dicotyledons). Nomenclature of families, genera, and species, as well as common names, follows Wunderlin and Hansen (2003, 2005). Names marked with an asterisk are exotic (n on-native) taxa. Names in bold type are the taxa endemic to Florida. Underlined names ar e new records for Hillsborough County. Common names follow the scientific name and authority. Common names are followed by the plant community in which the vascular plant taxa were collected. Plant community abbreviations are as follows: blackwater stream (BS), floodplain swamp (FS), floodplain forest (FF), floodplain marsh (FM), hydric hammock (HH), seepage slope (SS), wet flatwoods (WF), mesic flatwoods (MF), scrubby flatwoods (SF), sandhill (SH), xeric hammock (XH), and ruderal/developed (RD). Mesic flatwoods and the hydric hammock have associated dome swamp (DS) and sinkhole (SI) wetlands within them. These are abbreviated MF(DS), MF(SI), and HH(DS). Multiple plant communities listed reflect where collections were made. Plant community abbreviations are followed by the relative abundance within the pl ant community a collection was made and is abbreviated as: Common (C) (taxa abundant th roughout), Frequent (F) (taxa easily found throughout but not as abundant), Occasional (O) (t axa found sporadically throughout), Locally Common (LC) (taxa sporadically found throughout only in groups of individuals), and Rare (R) (taxa with one to very few individuals throughout ). Where a taxon is listed as an invasive species by the Florida Exotic Pest Pant Council (FLEPPC) a notation of [CAT I] or [CAT II] is given
85 following the relative abundance (FLEPPC 2003). Collection numbers from the present floristic inventory or the collectors name and collecti on number of previous collections, not documented and collected during the present study, are in italics at the end of the taxa citation. PTERIDOPHYTES (FERNS AND FERN ALLIES) ASPLENIACEAE Asplenium platyneuron (L.) Britton et al.ebony spleenwort; FF, FS, SS; F; Wunderlin et. al. 6416 AZOLLACEAE Azolla caroliniana Willd.mosquito fern; BS; C; 250 BLECHNACEAE Woodwardia areolata (L.) T. Moorenetted chain fern; SS; O; 510 Woodwardia virginca (L.) Sm.Virginia chain fern; FS, MF(DS), SS; LC, O; 505 NEPHROLEPIDACEAE Nephrolepis cordifolia (L.) C. Presltuberous sword fern; FF, WF; O; [CAT 1]; 334 OSMUNDACEAE Osmunda regalis L. var. spectabilis (Willd.) A. Grayroyal fern; FS; F; 216 PSILOTACEAE Psilotum nudum (L.) P. Beauv.whisk-fern; FS, HH; Wunderlin et al. 6400 PTERIDACEAE Ceratopteris thalictroides (L.) Brongn.watersprite; BS; O; 294, 351 SALVINIACEAE Salvinia minima Bakerwater spangles; BS; C; 249
86 SCHIZAEACEAE Lygodium japonicum (Thunb.) Sw.Japanese climbing fern; FS, HH, RD; R; [CAT I]; Wunderlin et al. 6419 THELYPTERIDACEAE Thelypteris dentata (Forssk.) E.P. St. Johndowny maiden fern; FS, HH; R; Richardson 1002 Thelypteris interrupta (Willd.) K. Iwats.hottentot fern; FF; O; 359 GYMNOPSERMS CUPRESSACEAE Taxodium distichum (L.) Rich.bald-cypress; BS, FF, FS, HH(DS), MF(DS); C; Richardson 1004 PINACEAE Pinus clausa (Chapm. ex Engelm.) Vasey ex Sarg.sand pine; XH; F; 188 Pinus elliottii Engelm.slash pine; WF; O; 164 Pinus palustris Mill.longleaf pine; MF, SH; F; Richardson 1055 Pinus taeda L.loblolly pine; MF; R; Wunderlin 10197 ANGIOSPERMS (MONOCOTYLEDONS) AGAVACEAE Yucca filamentosa L.Adam's needle; SH; O; 410 ALISMATACEAE Sagittaria graminea Michx. var. chapmanii J.G. Sm.Chapman's arrowhead; FS; F; 165 AMARYLLIDACEAE Zephyranthes atamasca (L.) Herb.atamasco lily; WF; R; Richardson 967
87 ARACEAE Lemna aequinoctialis Welw.lesser duckweed; BS; LC, O; 251 Pistia stratiotes L.water lettuce; BS; C; [CAT I]; 253 Spirodela polyrhiza (L.) Schleid.common duckweed; BS; C; 252 ARECACEAE Sabal minor (Jacq.) Pers.dwarf palmetto; FF; O; 354 Sabal palmetto (Walter) Lodd. ex Schult. & Schult. f.cabbage palm; FS, HH, MF, SF, SH, XH; O; 512 Serenoa repens (Bartr.) Smallsaw palmetto; MF, SH, XH; C; Richardson 913 BROMELIACEAE Tillandsia fasciculata Sw. var. densispica Mezcardinal airplant; FS, WF; R; 338 Tillandsia recurvata (L.) L.ballmoss; MF, XH; C; Barthe 108 Tillandsia setacea Sw.southern needleleaf; XH; C; 190, 211 Tillandsia simulata SmallFlorida air plant; FS, WF, XH; O; 212, 213, 337 Tillandsia usneoides (L.) L.Spanish moss; BS; C; 259 COMMELINACEAE Commelina diffusa Burm. F.common dayflower; FF, RD; OF; 229, 295 350 Commelina erecta L.whitemouth dayflower; RD, XH; R; Bancroft J-20 CYPERACEAE Bulbostylis ciliatifolia (Elliott) Fernaldcapillary hairsedge; SH; OF; 18 Bulbostylis stenophylla (Elliott) C.B. Clarkesandyfield hairsedge; SH; F; 86 Bulbostylis warei (Torr.) C.B. ClarkeWare's hairsedge; SH; O; 19 Carex alata Torr.broadwing sedge; BS, FF; R; 361, 366A Carex gigantea Rudgegiant sedge; FS; O; 322 Carex longii MackLongs sedge; FF, WF; R; Richardson 1085
88 Carex lupuliformis Sartwell ex Deweyfalse hop sedge; BS, FS; O; 366 Carex verrucosa Muhl.warty sedge; FS, HH(DS), MF(DS), SS, WF; R; Richardson 986 Carex vexans F.J. Herm.Florida hammock sedge; BS, FF, FS; R; 368 Cyperus croceus VahlBaldwin's flatsedge; SH; O; 406 Cyperus esculentus L.yellow nutgrass; SH; O; 87 Cyperus filiculmis Vahlwiry flatsedge; SH; RO; 411 Cyperus haspan L.haspan flatsedge; BS, SS, WF; R; Richardson 1090 Cyperus odoratus L.fragrant flatsedge; RD; F; 371 Cyperus polystachyos Rottb.manyspike flatedge; RD; F; 372 Cyperus retrorsus Chapm.pinebarren flatsedge; SH; O; 407 Cyperus surinamensis Rottb.tropical flatsedge; FS, WF; R; Richardson 1082 Eleocharis vivipara Linkviviparous spikerush; SS; O; 291 Fimbristylis caroliniana (Lam.) FernaldCarolina fimbry; WF; O; 38 Fimbristylis puberula (Michx.) Vahlhairy fimbry; WF; R; Richardson 987 Rhynchospora colorata (L.) H. Pfeiff.starrush whitetop; BS, RD; O; 228 Rhynchospora corniculata (Lam.) A. Grayshortbristle horned beaksedge; FS; F; 1 316 344 Rhynchospora fascicularis (Michx.) Vahlfascicled beaksedge; FF, SS, WF; O; 95 Rhynchospora globularis (Chapm.) Smallglobe beaksedge; WF; O; 179 Rhynchospora grayi KunthGray's beaksedge; SH; R; 111, 416 Rhynchospora megalocarpa A. Graysandyfield beaksedge; XH; O; 2 191 Rhynchospora microcarpa Baldwin ex A. Graysouthern beaksedge; FF, FS, HH, WF; C; 273 Rhynchospora mixta Britton ex Smallmingled beaksedge; BS, FS; O; 355, 363 Rhynchospora pusilla Chapm. ex M.A. Curtisfairy beaksedge; WF; O; 39 Scirpus tabernaemontani C.C. Gmel.softstem bulrush; FS, WF; R; Richardson 969
89 Scleria ciliata Michx. var. pauciflora (Muhl. ex Willd.) Kk.fewflower nutrush; FS, WF; R; Ray et al.10216 Scleria reticularis Michx.netted nutrush; FS, SS; WF; R; Bancroft J-23 Scleria triglomerata Michx.tall nutgrass; XH; O; 5 192 Scleria verticillata Muhl. ex Willd.low nutrush; WF; R; Richardson 2011 ERIOCAULACEAE Eriocaulon decangulare L.tenangle pipewort; SS; LC, O; 290 Lachnocaulon anceps (Walter) Morongwhitehead bogbutton; SS, WF; OF; 41, 94 169 177, 280, 289 Syngonanthus flavidulus (Michx.) Ruhlandyellow hatpins; SS, WF; OF; Richardson 1084 HAEMODORACEAE Lachnanthes caroliana (Lam.) DandyCarolina redroot; SS, WF; OF; Bateson 67 HYPOXIDACEAE Hypoxis curtissii Rosecommon yellow stargrass; FF, FS, WF; R; 32, 167 Hypoxis juncea Sm.fringed yellow stargrass; SS, WF; R; Lewis 21 Hypoxis wrightii (Baker) Brackettbristleseed yellow stargrass; WF; R; 46 IRIDACEAE Sisyrinchium angustifolium Mill.narrowleaf blue-eyed grass; FF, HH, WF; C; 227, 271 JUNCACEAE Juncus dichotomus Elliottforked rush; SS, WF; R; Richardson 1045 Juncus effusus L. subsp. solutus (Fernald & Wiegand) Hmet-Ahtisoft rush; SS, WF; LC, O; Richardson 977 Juncus elliottii Chapm.bog rush; SS, WF; R; Richardson 915 Juncus marginatus Rostk.shore rush; FF, SS, WF; C; 272, 279
90 Juncus repens Michx.lesser creeping rush; SS; LC, O; 514 Juncus scirpoides Lam.needlepod rush; WF; F; 26 ORCHIDACEAE Calopogon tuberosus (L.) Britton et al.tuberous grasspink; SS, WF; LC, R; 245 314 Encyclia tampensis (Lindl.) SmallFlorida butterfly orchid; FF, FS; R; 377 Epidendrum conopseum R. Br.green-fly orchid; FS, SS, WF; R; Richardson 893 Habenaria repens Nutt.waterspider false reinorchid; BS, MF(DS), WF; R; Richardson 972 Pteroglossaspis ecristata (Fernald) Rolfegiant orchid; MF, SH; R; Richardson 2019 Spiranthes odorata (Nutt.) Lindl.fragrant ladiestresses; FF, FS, WF; R; Richardson 2007 Spiranthes vernalis Englem. & A. Grayspring ladiestresses; FF, FS, SS, WF; R; Richardson 1022 POACEAE Andropogon glomeratus (Walter) Britton et al. var. glaucopis (Elliott) C. Mohrpurple bluestem; SS, WF; LC, O; 511 Andropogon glomeratus (Walter) Britton et al. var. pumilus (Vasey) Vasey ex L.H. Dewey bushy bluestem; SH, WF; O; Vincent 165 Andropogon longiberbis Hack.hairy bluestem; SH; R; Richardson 1095 Andropogon ternarius Michx.splitbeard bluestem; SH; O; 129 Andropogon tracyi NashTracy's bluestem; SH; O; 84 85 116 Anthaenantia villosa (Michx.) P. Beauv.green silkyscale; SH; O; 124 Aristida stricta Michx. var. beyrichiana (Trin. & Rupr.) D.B. Wardwiregrass; SH; F; 119, 127 Aristida purpurascens Poir.arrowfeather threeawn; SH; O; 130 Axonopus fissifolius (Raddi) Kuhlm.common carpetgrass; WF; R; Richardson 1050 Axonopus furcatus (Flgg) Hitchc.big carpetgrass; FF, HH, SS; C; 274, 364 Cenchrus gracillimus Nashslender sandbur; SH; O; 118, 399
91 Dichanthelium aciculare (Desv. ex Poir.) Gould & C.A. Clarkneedleleaf witchgrass; MF, SF, SH; R; Richardson 2000 Dichanthelium commutatum (Schult.) Gouldvariable witchgrass; BS, FF, FS; OC; 296, 333, 357 Dichanthelium dichotomum (L.) Gouldcypress witchgrass; FF, HH, WF; C; 33, 270 318 Dichanthelium ensifolium (Baldwin ex Elliott) Gould var. unciphyllum (Trin.) B.F. Hansen & Wunderlincypress witchgrass; HH, MF, SH, WF; O; Richardson 908 Dichanthelium leucothrix (Nash) Freckmannrough witchgrass; FF, HH, MF, WF; O; 282 Dichanthelium ovale (Elliott) Gould & C.A. Clarkeggleaf witchgrass; SH; O; 55, 233, 311, 380 415 Dichanthelium portoricense (Desv. ex Ham.) B.F. Hansen & Wunderlinhemlock witchgrass; MF, SH; O; 56, 157 381 396 398 414 Dichanthelium strigosum (Muhl. ex Elliott) Freckmann var. glabrescens (Griseb.) Freckmann roughhair witchgrass; FF, WF; O; 281 Digitaria serotina (Walter) Michx.blanket crabgrass; SH; O; Richardson 1097 Echinochloa muricata (P. Beauv.) Fernaldrough barnyardgrass; BS, FF, FS, HH; O; 258 Echinochloa walteri (Pursh) A. Hellercoast cockspur; RD; R; Richardson 992 Eragrostis elliottii S. WatsonElliott's lovegrass; SH; F; 100, 101, 104 Eragrostis virginica (Zuccagni) Steud.coastal lovegrass; WF; R; Richardson 1083 Eustachys glauca Chapm.saltmarsh fingergrass; WF; O; 178 Eustachys neglecta (Nash) Nashfourspike fingergrass; MF, SH; F; 110, 121, 137 Gymnopogon ambiguus (Michx.) Britton et al.bearded skeletongrass; MF, SH; R; Hilsenbeck & Stenholm 23 Panicum anceps Michx.beaked panicum; SH; LC, O; 61, 133 Panicum hemitomon Schult.maidnecane; FS; O; Richardson 1096
92 Panicum rigidulum Bosc ex Neesredtop panicum; FF, FS, HH; O; 320 Panicum virgatum L.switchgrass; WF; LC, O; 141 Paspalum repens P.J. Bergiuswater paspalum; BS, FS; F; 261 Paspalum setaceum Michx.thin paspalum; SH; O; 69, 88 122 135 Rhynchelytrum repens (Willd.) C.E. Hubb.rose natalgrass; SH; LC, R; [CAT II]; 76 Schizachyrium scoparium (Michx.) Nashlittle bluestem; SF; R; Bancroft 4 Setaria parviflora (Poir.) Kergulenyellow bristlegrass; SH; O; 57 123, 405 Sorghastrum secundum (Elliott) Nashlopsided Indiangrass; SH; F; 99 Sporobolus indicus (L.) R. Br.smutgrass; SH; R; Richardson 1038 Sporobolus junceus (P. Beauv.) Kunthpineywoods dropseed; SH, XH; OC; 17, 237, 384, 408 Triplasis americana P. Beauv.perennial sandgrass; SH; O; 117 Urochloa mutica (Forssk.) T.Q. Nguyenparagrass; RD; LC, R; [CAT I]; 369 PONTEDERIACEAE Eichhornia crassipes (Mart.) Solmscommon water-hyacinth; BS, FS; LC, O; [CAT I]; Peaden & Ford 17 Pontederia cordata L.pickerelweed; BS, FS; O; 218 SMILACACEAE Smilax auriculata Walterearleaf greenbrier; SH, MF; O; 243, 403 Smilax bona-nox L.saw greenbrier; FS; R; Richardson 1016 Smilax pumila Waltersarsaparilla vine; FS; R; Richardson 1001 TYPHACEAE Typha domingensis Pers.southern cattail; FS; R; Richardson 971 XYRIDACEAE Xyris brevifolia Michx.shortleaf yelloweyed grass; SS; R; Richardson 893 Xyris caroliniana WalterCarolina yelloweyed grass; WF; O; 25, 51
93 Xyris elliottii Chapm.Elliott's yelloweyed grass; SS, WF; LC, OF; 277, Xyris jupicai Rich.Richard's yelloweyed grass; WF; O; 199 ANGIOSPERMS (DICOTYLEDONS) ACANTHACEAE Dyschoriste oblongifolia Michx. Kuntzeoblongleaf twinflower; SH; O; Richardson 957 Ruellia caroliniensis (J.F. Gmel.) Steud.Carolina wild petunia; SH; O; 15 Ruellia ciliosa Purshciliate wild petunia; XH; R; 239; Long 1198 ADOXACEAE Viburnum obovatum WalterWalter's viburnum; FF, FS, HH; F; 154 Sambucus nigra L. subsp. canadensis (L.) R. Bolli.elderberry; FS; R; Richardson 989 AMARANTHACEAE Alternanthera philoxeroides (Mart.) Griseb.alligatorweed; BS, FS; LC, O; [CAT II]; 224, 265 Amaranthus spinosus L.spiny amaranth; RD; R; Bateson 193 Chenopodium ambrosioides L.Mexican tea; RD; R; Richardson 1070 Froelichia floridana (Nutt.) Moq.cottonweed; SH; O; 74, 79 82 Gomphrena serrata L.globe amaranth; RD; LC, O; 9 ANACARDIACEAE Rhus copallinum L.winged sumac; MF, SF, SH, XH; O; 92 Schinus terebinthifolius RaddiBrazilian pepper; RD; R; [CAT I]; Bateson 62 Toxicodendron radicans (L.) Kuntzeeastern poison ivy; FF, FS, HH, MF, WF; O; 168 ANNONACEAE Asimina pygmea (Bartr.) Dunal.dwarf pawpaw; SH, XH; RO; 391, 397 Asimina reticulata Shuttlew. ex Chapm.netted pawpaw; SF, SH, XH; O; Richardson 909
94 APIACEAE Cicuta maculata L.spotted water hemlock; BS, FS; O; 223 Erynigium baldwinii Spreng.Baldwin's eryngo; BS, FF, FS, HH; O; 158, 367 Ptilimnium capillaceum (Michx.) Raf.mock bishopweed; BS, FS; O; 215 APOCYNACEAE Asclepias humistrata Walterpinewoods milkweed; SH, XH; O; 238 Asclepias longifolia Michx.longleaf milkweed; WF; O; 241 Asclepias perennis Walterswamp milkweed; FF, FS; RO; 28, 340 Asclepias tuberosa L.butterflyweed; SH; RO; 298, 417 Asclepias verticillata L.whorled milkweed; SH; R; 63, 303, 312, 401 Matelea pubiflora (Decne.) Woodsontrailing milkvine; SH; R; 306 AQUIFOLIACEAE Ilex ambigua (Michx.) Torr.Carolina holly; XH; O; 3 Ilex cassine L.dahoon; FF, FS, HH; R; 48, 276 Ilex decidua Walterpossumhaw; FF; RO; 182, 214 Ilex glabra (L.) A. Graygallberry; MF, SH, WF; LC, O; Bateson 63 ARALIACEAE Centella asiatica (L.) Urb.spadeleaf; BS, FF, FS; O; 362 Hydrocotyle verticillata Thunb.whorled marshpennywort; BS, FM, FS; F; 260 276 ASTERACEAE Ageratina jucunda (Greene) Clewell & Wootenhammock snakeroot; MF, SH; O; 115 Ambrosia artemisiifolia L.common ragweed; RD; C; 10 Arnoglossum floridanum (A. Gray) H. Rob.Florida Indian plantain; SF, SH, XH; RO; 53, 310 402 Balduina angustifolia (Pursh) B.L. Rob.coastalplain honeycombhead; SH; OF; 59, 113
95 Berlandiera subacaulis (Nutt.) Nutt.Florida greeneyes; SH; O; 65, 235 Bidens alba (L.) DC. var. radiata (Sch. Bip.) R.E. Ballard ex Me lchertbeggarticks; RD; LC, O; Bateson 69 Carphephorus corymbosus (Nutt.) Torr. & A. GrayF lorida paintbrush; SH; F; 98 Chrysopsis linearifolia Semple subsp. dressii SempleDress' goldenaster; SH; R; Jones 42 Chrysopsis mariana (L.) ElliottMaryland goldenaster; XH; O; King 91 Chrysopsis scabrella Torr. & A. Graycoastalplain goldenaster; SH; O; 128, 383 Chrysopsis subulata Smallscrubland goldenaster; MF; R; Jourdan & Crewz s.n. Cirsium nuttallii DC.Nuttall's thistle; FF, FS, HH; LC, R; 315 Conyza canadensis (L.) Cronquist var. pusilla (Nutt.) Cronquistdwarf Canadian horseweed; RD; F; 78 Coreopsis leavenworthii Torr. & A. GrayLeavenworth's tickseed; WF; O; 44 181 Eclipta prostrata (L.) L.false daisy; BS, FF, FS, HH; O; 225, 255 346, 348 Elephantopus elatus Bertol.tall elephantsfoot; SH; F; 67 Erechtites hieraciifolius (L.) Raf. ex DC.fireweed; WF; O; 186, 283 Erigeron quercifolius Poir.oakleaf fleabane; RD; O; 231 Erigeron vernus (L.) Torr. & A. Grayslenderleaf fleabane; SH; O; Richardson 952 Eupatorium compositifolium Walteryankeeweed; SH; O; 105 Eupatorium leptophyllum DC.falsefennel; WF; F; 147 Eupatorium mohrii GreeneMohr's thoroughwort; SH; O; Richardson 981 Euthamia caroliniana (L.) Greene ex Porter & Brittonslender goldenrod; MF, SF, SH; OF; 125 Gamochaeta pensylvanica (Willd.) CabreraPennsylvania everlasting; SH; R; Richardson 966 Helenium flexuosum Raf.purplehead sneezeweed; WF; O; 376. Helianthus angustifolius L.narrowleaf sunflower; RD; R; Robbins 86
96 Helianthus radula (Pursh) Torr. & A. Graystiff sunflower; SH; R; Brunn 1 Heterotheca subaxillaris (Lam.) Britton & Rusbycamphorweed; RD, SH; O; Hilsenbeck Schweinter 10 Hieracium gronovii L.queendevil; SH; R; 60 Hieracium megacephalon Nash coastalplain hawkweed; SH; R; 313, 394, 413 Lactua graminifolia Michx.grassleaf lettuce; RD; R; Richardson 1048 Liatris gracilis Purshslender gayfeather; SH; O; 75 Liatris pauciflora Purshfewflower gayfeather; SH; O; 68 Liatris tenuifolia Nutt.shortleaf gayfeather; SH; O; 103 Liatris tenuifolia Nutt.var. quadriflora Chapm.shortleaf gayfeather; SH; XH; O; 148, 151 Mikania scandens (L.) Willd.climbing hempvine; BS, FM; F; Bateson 70 Packera glabella (Poir.) C. Jeffreybutterweed; FS, WF; O; 240, 319 Palafoxia integrifolia (Nutt.) Torr. & A. Graycoastalplain palafox; SH; O; 102 Phoebanthus grandiflorus (Torr. & A. Gray) S. F. BlakeFlorida false sunflower; SH; O; 80 Pityopsis graminifolia (Michx.) Nutt.narrowleaf silkgrass; SH; OF; 77, 140 Pluchea rosea R. K. Godfreyrosy camphorweed; WF; O; Richardson 996 Pterocaulon pycnostachyum (Michx.) Elliottblackroot; MF, SH; O; 373. Pyrrhopappus carolinianus (Walter) DC.Carolina desertchicory; RD, SH; O; Richardson 1075 Sericocarpus tortifolius (Michx.) Neeswhitetop aster; SF, SH; O; 131 Solidago fistulosa Mill.pinebarren goldenrod; MF, SH, WF; O; King 156 Solidago leavenworthii Torr. & A. GrayLeavenworth's goldenrod; WF; O; 292 Solidago stricta Aitonwand goldenrod; SH; O; 132 Symphyotrichum carolinianum (Walter) Wunderlin & B.F. Hansenclimbing aster; BS, FS; O; 257 Symphyotrichum concolor (L.) G.L. Nesomeastern silver aster; SH; O; 120
97 Symphyotrichum dumosum (L.) G.L. Nesomrice button aster; MF, SH; O; 108, 143 Youngia japonica (L.) DC.Oriental false hawkweed; RD; O; 263 BETULACEAE Carpinus caroliniana WalterAmerican hornbeam; FF; F; 352 BIGNONIACEAE Campsis radicans (L.) Seemanntrumpet creeper; FF, MF, RD, WF; F; 332 BORAGINACEAE Onosmodium virginianum (L.) DC.false Gromwell; SH; R; 307 BRASSICACEAE Cardamine pensylvanica Muhl. ex Willd.Pennsylvania bittercress; FF, HH; O; 160 Lepidium virginicum L.Virginia pepperweed; RD; O; 386 CACTACEAE Opuntia humifusa (Raf.) Raf.pricklypear; SH; O; 299 CAMPANULACEAE Lobelia glandulosa Walt.glade lobelia; WF; R; 142, 146 Lobelia paludosa Nutt.white lobelia; WF; R; Richardson 999 CARYOPHYLLACEAE Stipulicida setacea Michx. var. lacerata C.W. Jamespineland scalypink; MF, SF; O; 374 CHRYSOBALANCEAE Licania michauxii Prancegopher apple; SH; O; 304 CISTACEAE Helianthemum corymbosum Michx.pinebarren frostweed; SH, XH; O; 139, 183 Lechea minor L.thymeleaf pinweed; MF, SH, XH; F; 20, 24 Lechea mucronata Raf.hairy pinweed; SH; O; Jourdan & Crewz s.n. Lechea sessiliflora Raf.pineland pinweed; SH; F; 134
98 CLUSIACEAE Hypericum fasciculatum Lam.sandweed; FS, WF; O; Richardson 1068 Hypericum gentianoides (L.) Britton et al.pineweeds; WF; O; 36 Hypericum hypericoides (L.) CrantzSt. Andrew's-cross; FF, FS, WF; OF; 30 49 Hypericum mutilum L.dwarf St. John's-wort; FF, FS, WF; O; 284 Hypericum tetrapetalum Lam.fourpetal St. John's-wort; WF; O; 27, 47 CONVOLVULACEAE Dichondra caroliniensis Michx.Carolina ponysfoot; FF, RD; O; 185 Ipomoea cordatotriloba Dennst.tievine; RD; R; Bateson 60 Ipomoea pandurata (L.) G. Mey.man-of-the-earth; SH; R; Richardson 1018 Stylisma patens (Desr.) Myintcoastalplain dawnflower; SH; O; 14 CORNACEAE Cornus foemina Mill.swamp dogwood; FF, FS; F; 206 CUCURBITACEAE Melothria pendula L.creeping cucumber; FF; O; 365 Momordica charantia L.balsampear; RD; R; Bateson 65 DROSERACEAE Drosera capillaris Poir.pink sundew; WF; C; 324 EBENACEAE Diospyros virginiana L.common persimmon; MF, SF, SH, WF; F; 138, 210, 301 ERICACEAE Lyonia ferruginea (Walter) Nutt.rusty staggerbush; XH; F; 6 172 Lyonia fruticosa (Michx.) G.S. Torr.coastalplain staggerbush; MF, SF, SH; O; Barthe 89 Lyonia lucida (Lam.) K. Kochfetterbush; WF; R; Barthe 69 Vaccinium arboreum Marshallsparkleberry; MF, SF, SH, XH; OF; 23, 163, 196
99 Vaccinium corymbosum L.highbush blueberry; SS, WF; O; 197, 204; Vaccinium darrowii CampDarrow's blueberry; MF, SF, SH, WF; OF; Richardson 932 Vaccinium myrsinites Lam.shiny blueberry; MF, SF, SH, WF; OF; 195 Vaccinium stamineum L.deerberry; MF, SH, XH; C; 232, 392 395 EUPHORBIACEAE Acalypha gracilens A. Grayslender threeseed mercury; RD, SH; O; 83 Chamaesyce hirta (L.) Millsp.pillpod sandmat; RD, SH; O; Richardson 1053 Chamaesyce maculata (L.) Smallspotted sandmat; RD, SH; O; Richardson 1054 Cnidoscolus stimulosus (Michx.) Engelm. & A. Graytread softly; SH; O; 236 Croton argyranthemus Michx.silver croton; SH; O; 71, 393 Croton glandulosus L.vente conmigo; SH; R; 81 Croton michauxii G.L. Websterrushfoil; RD, XH; F; 21 Stillingia sylvatica L.queensdelight; SH; O; 62, 234 302 Tragia urens L.wavy noseburn; SH; O; 382 FABACEAE Astragalus obcordatus ElliottFlorida milkvetch; SH; R; Richardson 1052 Baptisia lecontei Torr. & A. Graypineland wild indigo; SH; O; 309 Chamaecrista fasciculata (Michx.) Greenepartridge pea; MF, SH; OF; 11, 375 Chamaecrista nictitans (L.) Moench var. aspera (Muhl.ex Elliott) H.S. Irwin & Barneby sensitive pea; MF, SH; O; Willett 54 Clitoria mariana L.Atlantic pigeonwings; SH; R; 300. Crotalaria rotundifolia J.F. Gmel.rabbitbells; SH; R; 58 Dalea carnea (Michx.) Poir.whitetassels; SH; O; 16 Dalea pinnata (J.F. Gmel.) Barnebysummer farewell; SH, XH; O; 114, 144 Desmodium floridanum Chapm.Florida ticktrefoil; SH; O; 13, 136
100 Desmodium incanum DC.zarzabacoa comun; RD; R; Bateson 123 Desmodium paniculatum (L.) DC.panicled tricktrefoil; SH; R; Vincent 23 Galactia volubilis (L.) Brittondowny milkpea; SH; O; 54, 244 Gleditsia aquatica Marshallwater locust; FS; O; Richardson 946 Indigofera caroliniana Mill.Carolina indigo; SH; O; Jourdan & Crewz s.n. Indigofera hirsuta L.hairy indigo; RD; O; Lewis 4 Lespedeza hirta (L.) Hornem.hairy lespedeza; SH; O; 126 Lupinus diffusus Nutt.skyblue lupine; SH; F; 200, 209 Mimosa quadrivalvis L. var. angustata (Torr. & A. Gray) Barnebysensitive brier; SH; O; 308 Rhynchosia michauxii VailMichaux's snoutbean; SH; O; 305, 404 Rhynchosia reniformis DC.dollarleaf; SH; O; 70 Senna obtusifolia (L.) H.S. Irwin & Barnebycoffeeweed; RD; R; Bancroft K-5 Sesbania herbacea (Mill.) McVaughdanglepod; RD; R; Bateson 156 Stylosanthes biflora (L.) Britton et al.sidebeak pencilflower; MF, SH; R; Wunderlin et al. 5616 Tephrosia chrysophylla Purshscurf hoarypea; SH; O; 72, 73 412 Tephrosia florida (F. Dietr.) C.E. WoodFlorida hoarypea; SH; R; Richardson 1049 Vicia acutifolia Elliottfourleaf vetch; BS, FS, HH, RD, WF; R; Richardson 950 Vigna luteola (Jacq.) Benth.hairypod cowpea; RD; R; Bateson 163 FAGACEAE Quercus chapmanii Sarg.Chapman's oak; SF, SH, XH; RO; 149, 150 Quercus geminata Smallsand live oak; SF, SH, XH; OF; 97 Quercus incana W. Bartrambluejack oak; SH, XH; O; 106 Quercus myrtifolia Willd.myrtle oak; SF, SH, XH; R; 409 Quercus laevis Walterturkey oak; SH, XH; F; Kaczor s.n. Quercus laurifolia Michx.laurel oak; FF, HH, WF; F; 93, 170
101 Quercus nigra L.water oak; WF; R; Richardson 1013 Quercus virginiana Mill.Virginia live oak; MF, SF, SS, XH; O; 96 GELSEMIACEAE Gelsemium sempervirons (L.) W.T. Aitonyellow jessamine; WF; LC, O; 180 GENTIANACEAE Sabatia brevifolia Raf.shortleaf rosegentian; WF; O; 35 Sabatia calycina (Lam.) A. Hellercoastal rosegentian; FF, FS, HH; O; 321 Sabatia grandiflora (A. Gray) Smalllargeflower rosegentian; WF; O; Weinland 2` HALORAGACEAE Proserpinaca palustris L.marsh mermaidweed; BS; C; 347 ITEACEAE Itea virginica L.Virginia willow; FS; O; 207 KRAMERIACEAE Krameria lanceolata Torr.sandspur; SH; O; 379 LAMIACEAE Callicarpa americana L.American beautyberry; XH; O; Wunderlin et al. 6409 Hyptis alata (Raf.) Shinnersclustered bushmint; WF; O; Massetti 28 Piloblephis rigida (W. Bartram ex Benth.) Raf.wild pennyroyal; MF, SF; O; 194 Scutellaria arenicola SmallFlorida scrub skullcap; SH; O; 66 Stachys floridana Shuttlew. ex Benth.Florida betony; RD; O; Richardson 1037 Trichostema dichotomum L.forked bluecurls; MF, SH; O; Willett 1 LAURACEAE Persea borbonia (L.) Spreng.red bay; XH; O; 4 173
102 LENTIBULARIACEAE Pinguicula caerulea Walterblueflower butterwort; SS, WF; R; Richardson 897 Pinguicula pumila Michx.small butterwort; WF; O; 152, 193 Utricularia inflata Walterfloating bladderwort; FS; LC, O; Richardson 973 Utricularia subulata L.zigzag bladderwort; MF(SI), WF; O; 203 LINACEAE Linum medium (Planch.) Britton var. texanum (Planch.) Fernaldstiff yellow flax; WF; O; 42 50 LOGANIACEAE Mitreola petiolata (J.F. Gmel.) Torr. & A. Graylax hornpod; FS; O; Perkey 143 LYTHRACEAE Lythrum flagellare Shuttlew. ex Chapm.Florida loosestrife; HH; LC, R; 267 MALVACEAE Sida cordifolia L.Llima; RD; R; Bancroft K-2 Sida rhombifolia L.Cuban jute; BS, FF; R; 297 Urena lobata L.ceasarweed; RD; O; [CAT II]; 356 MELASTOMATACEAE Rhexia mariana L.pale meadowbeauty; WF; O; 278, 335 MYRICACEAE Myrica cerifera L.wax myrtle; FF, FS, HH, MF, WF; OF; 45 166 184 OLACACEAE Ximenia americana L.hog plum; SH; R; Bateson 54 OLEACEAE Chionanthus virginicus L.white fringetree; MF, XH; LC, O; 189, 205, 242 Fraxinus caroliniana Mill.pop ash; BS, FF, FS, HH; C; 176, 217 222, 331
103 ONAGRACEAE Guara angustifolia Michx.southern beeblossum; RD, SH; LC, O; 385 Ludwigia maritima R.M. Harperseaside primrosewillow; SH, WF; R; Richardson 1039 Ludwigia microcarpa Michx.smallfruit primrosewillow; FS; O; Richardson 1069 Ludwigia palustris (L.) Elliottmarsh seedbox; FS; O; Richardson 976 Oenothera laciniata Hillcutleaf evening primrose; RD; LC, R; Richardson 1009 OROBANCHACEAE Agalinis fasciculata (Elliott) Raf.beach false foxglove; WF; O; 325 Agalinis setacea (J.F. Gmel.) Raf.threadleaf false foxglove; SH; R; Richardson 2005 Aureolaria pedicularia (L.) Raf. var. pectinata (Nutt.) Gleasonfernleaf yellow false foxglove; SH, XH; R; 8 8a Seymeria cassioides (J.F. Gmel.) S. F. Blakeyaupon blacksenna; SH; R; Jones 37 Seymeria pectinata PurshPiedmont blacksenna; SF, SH, XH; O; 22 OXALIDACEAE Oxalis corniculata L.common yellow woodsorrel; FF, HH, MF, RD; F; 159, 230 269 PHYTOLACCACEAE Phytolacca americana L.American pokeweed; RD; R; Richardson 911 PLANTAGINACEAE Plantago virginica L.Virginia plantain; RD; O; 246 POLYGALACEAE Polygala cruciata L.drumheads; WF; R; 326 Polygala lutea L.orange milkwort; WF; R; 330 Polygala nana (Michx.) DC.candyroot; WF; O; 40 Polygala rugelii Shuttlew. ex Chapm.yellow milkwort; WF; O; 329
104 Polygala setacea Michx.coastalplain milkwort; WF; R; Richardson 899 Polygala violacea Aubl.showy milkwort; SH; O; 52 64 POLYGONACEAE Eriogonum tomentosum Michx.wild buckwheat; SF; F; 12 Polygonella gracilis Meisn.tall jointweed; SH; O; 112 Polygonella polygama (Vent.) Engelm. & A. Grayoctober flower; MF; O; 89, 90, 91, 107 Polygonum densiflorum Meisn.knotweed; BS, FS; R; Bateson 5 Polygonum hydropiperoides Michx.swamp smartweed; FS, MF(DS); R; Richardson 1071 Polygonum punctatum Elliottdotted smartweed; BS; F; 220, 254 264 Rumex hastatulus Baldwinhastateleaf dock; RD; R; Richardson 941 Rumex verticillatus L.swamp dock; BS; F; 248, 343 PORTULACACEAE Portulaca oleracea L.little hogweed; RD, SH; O; 387 Portulaca pilosa L.,pink purslane; RD, SH; O; 388 PRIMULACEAE Samolus valerandi L. subsp. parviflorus (Raf.) Hultnpineland pimpernel; BS, FF, FS; O; 262, 349 RHAMNACEAE Berchemia scandens (Hill) K. Kochrattan vine; FF, FS, HH; R; 513 ROSACEAE Crataegus michauxii Pers.Michaux's hawthorn; SH, XH; R; 378, 389 Prunus serotina Ehrh.black cherry; RD; R; 161 Prunus umbellata Elliottflatwoods plum; SH, XH; O; 198, 390 Rubus argutus Linksawtooth blackberry; RD; LC, R; Richardson 927
105 RUBIACEAE Cephalanthus occidentalis L.common buttonbush; FF, FS; F; 323 Diodia teres Walterrough buttonweed; MF, SH; O; Richardson 1063 Diodia virginiana L.,Virginia buttonweed; FF, FS; F; 29 Galium tinctorium L.stiff marsh bedstraw; FS; C; 219, 285 339 Houstonia procumbens (J.F. Gmel.) Standl.innocence; SF, SH; O; 162, 175 Mitchella repens L.partridgeberry; SS; LC, R; 286 Oldenlandia uniflora L.clustered mille graines; FS, HH, SS, WF; O; 171, 187 287, 328 Psychotria sulzneri Smallshortleaf wild coffee; BS, FF; LC, R; 358 Richardia brasiliensis Gomestropical Mexican clover; FF, FS; R; 268 Richardia scabra L.rough Mexican clover; RD; LC, R; Richardson 1061 Spermacoce assurgens Ruiz & Pav.woodland false buttonweed; FS; LC, R; Richardson 983 RUTACEAE Zanthoxylum clava-herculis L. Hercules-club; SH; R; 7 208 SALICACEAE Salix caroliniana Michx.Carolina willow; FS; F; 201 SAPINDACEDAE Acer rubrum L.red maple; FF, FS, HH, SS, WF; O; 156 SAPOTACEAE Sideroxylon reclinatum Michx.Florida bully; FF; O; 360 SAURURACEAE Saururus cernuus L.lizard's tail; FF, FS; F; 342 SOLANACEAE Physalis arenicola Kearneycypresshead groundcherry; SH; O; Richardson 1059 Solanum americanum Mill.American black nightshade; RD; R; 202
106 TETRACHONDRACEAE Polypremum procumbens L.rustweed; WF; F; 37 TURNERACEAE Piriqueta cistoides (L.) Griseb. subsp. caroliniana (Walter) Arbopitted stripeseed; SH; O; 400 ULMACEAE Ulmus americana L.American elm; FF, FS, HH; O; Richardson 937 URTICACEAE Boehmeria cylindrica (L.) Sw.false nettle; BS, FS; O; 31, 221 256 VERBENACEAE Lantana camara (L).lantana; RD; R; [CAT 1]; Richardson 990 Phyla nodiflora (L.) Greeneturkey tangle fogfruit; FF, FS, HH, RD, WF; O; 34, 247 317 VERONICACEAE Gratiola hispida (Benth. ex Lindl.) Pollardrough hedgehyssop; MF, WF; O; 43 Gratiola pilosa Michx.shaggy hedgehyssop; SS, WF; R; Richardson 1026 Linaria canadensis (L.) Chaz.Canada toadflax; RD; F; 226 Lindernia grandiflora Nutt.Savannah false pimpernel; HH, WF; O; Richardson 975 Mecardonia acuminata (Walter) Small subsp. peninsularis (Pennell) Rossowaxilflower; SS; R; O. Lakela 23993 Micranthemum umbrosum (J.F. Gmel.) S. F. Blakeshade mudflower; BS, FS; C; 293 345 Penstemon multiflorus (Benth.) Chapm. ex Smallmanyflower beardtongue; SH, XH; O; Jourdan & Crewz s.n. Scoparia dulcis L.sweetbroom; FM, HH, WF; O; Richardson 1074
107 VIOLACEAE Viola lanceolata L.bog white violet; FF, HH, SS, WF; LC, O; 145 155 288 327 Viola palmate L.early blue violet; SH; O; 174 Viola sororia Willd.common blue violet; FF, HH; O; 153 VITACEAE Ampelopsis arborea (L.) Koehnepeppervine; FF; R; Richardson 974 Parthenocissus quinquefolia (L.) PlanchVirginia creeper; FF, RD; O; 341, 370 Vitis aestivalis Michx.summer grape; FF; O; 353 Vitis rotundifolia Michx.muscadine; WF; F; 336 Vitis shuttleworthii HouseCalloose grape; HH, SS, WF; O; 266
108 CONCLUSION The floristics and the 12 natural plant communities documented and mapped in the present study revealed that the USF Eco Area is a biologi cally rich and diverse natural area despite being somewhat compromised by surrounding anthropogenic perturbations and its small size. The diversity of integrated ecosystems in the USF Eco Area provides USF with an excellent resource for both education and research, much needed in this day and age of habitat loss and fragmentation and the accelerated extinction of species threatening the very essence of biodiversity. The extraordinary value of the USF Eco Area, along with its location, is irreplaceable. It provides many opportunities for forming partnerships with organizations and agencies such as Florida Department of Environmental Protection, Florida Division of Forestry, Florida Fish and Wildlife Conservation Commission, Hillsboroug h Countys environmental lands acquisition program, Southwest Florida Water Management District, and The Nature Conservany for management and monitoring that would also in cur educational potentials for students working along with personnel from the above groups. The USF Eco Area also provides many potential opportunities for education, research, and manageme nt grants from educational, conservation, environmental, and natural scien ce organizations and foundations.
109 LITERATURE CITED Abbey. E.A. 2004. Elemant Occurrence Report for USF Ecological Reasearch Area. Florida Natural Areas Inventory (FNAI), Tallahassee, Florida. Abrahamson, W.G. and D.C. Hartnett. 1990. Pi ne Flatwoods and Dry Prairies. P. 10349. In : Meyers, R.L. and J.J.Ewel (eds.). Ecosystems of Florida. University of Central Florida Press, Orlando, Florida. Bray, R. 2004. Watershed Excursions of the Hillsborough River. Southwest Florida Water Management District. (http:// www.swfwmd.state.fl.us/watershed/index.htm Brown, R.B., E.L. Stone, and V.W. Carlisle. 1990 Soils. p. 3569. In : Meyers, R.L. and J.J. Ewel (eds.). Ecosystems of Florida. University of Central Florida Press, Orlando, Florida. Bullen, R.P. 1952. Eleven Archeological Sit es in Hills borough County, Florida. Florida Geological Survey, Report of Investigations 8. Chen, E. and J.F. Gerber. 1990. Climate. P. 1134. In : Meyers, R.L. and J.J. Ewel (eds.). Ecosystems of Florida. University of Central Florida Press, Orlando, Florida. Coile, N.C. and M.A. Garland. 2003. Notes on Floridas Endangered and Threatened Plants. Botany Contribution No. 38, 4rth ed. (PDF version). Florida Department of Agriculture and Consumer Services, Division of Plant Industry. Gainesville, Florida. Collins, L.D. 2005. The Picnic Mound a nd Buck Island Revisited Doctorial Thesis. Unpublished. University of South Florida. Cowardin, L.M., V. Cater, F.C. Golet, and E.T. LaRoe. 1979. Classification of Wetlands and Deepwater Habitats of the United States. U.S. Fish and Wildlife Service Office of Biological Services (Technical Report), FWS/OBS 79-31. Washington, D.C. Doolittle, J.A., G. Schellentrager, and S. Poloetz. 1989. Soil Survey of Hillsborough County, Florida. Soil Conservation Service, U.S. Department of Agriculture, Washington, D.C. Ewel, K.C. 1990 Swamps. p. 2813. In : Meyers, R.L. and J.J.Ewel (eds.). Ecosystems of Florida. University of Central Florida Press, Orlando, Florida. Eyles, E.C., C.R. Harper, and N.M. White. 2002. Archeological Survey on the Campus of the University of South Florida, Tampa, 2001. Department of Anthropology, University of South Florida, Tampa, Florida. Florida Exotic Pest Plant Council. (FLEPPC). 2003. Florida Exotic Pest Plant Councils 2003 List of Invasive Species. (http://www.fleppc.org/).
110 Florida Natural Areas Inventory (FNAI) and Depa rtment of Natural Resources (DNR). 1990. Guide to the Natural Communities of Florida. Tallahassee, Florida. Greene, S.W. 1931. The Forest that Fire Made. American. Forests Vol. 37, No. 10, pp. 583 584, 618 Gurevitch, J., S.M. Scheiner, and G.A. Fox. 2002. The Ecology of Plants. Sinauer Press, Sunderland, Massachusetts. Hawes, L. 1986. USF Site, Name Stirred Struggles. Tampa Tribune; October 30, 1986. Kushlan, J.A. 1990. Swamps. p. 324363. In : Meyers, R.L. and J.J.Ewel (eds.). Ecosystems of Florida. University of Central Florida Press, Orlando, Florida. Larsen, R. 1995. Swamp Song A Natural History of Floridas Swamps. University Press of Florida. Gainesville, Florida. Lewelling, B.R., 2003, Extent of Areal Inunda tion of Riverine Wetlands Along Cypress Creek and the Peace, Alafia, North Prong Alafia and South Prong Alafia Rivers, West-Central Florida: U.S. Geological Survey Water-Resources Investigations Report 02-4254, 91 p. Meyers, R.L. and J.J. Ewel (eds.). 1990. Ecosyste ms of Florida. University of Central Florida Press, Orlando, Florida. Meyers, R.L. 1990. Scrub and High Pine. p. 15093. In : Meyers, R.L. and J.J.Ewel (eds.). Ecosystems of Florida. University of Central Florida Press, Orlando, Florida. Meyers, R.L. 2000. Physical Setting and Vegetation of Florida. p. 104. In : Wunderlin, R.P. and B.F. Hansen. 2000. Flora of Florida Volume 1 Pteridophytes and Gymnosperms. University Press of Florida. Gainesville, Florida. Milanich, J.T. 1994. Archaeology of Precolumb ian Florida. University Press of Florida, Gainesville, Florida. National Weather Service Tampa Bay Florida. 2005. 2004 Climate Scorecard for Tampa, Florida. (http//www.srh.noaa.gov). Nordlie, F.G. 1990 Rivers and Springs. p. 3925. In : Meyers, R.L. and J.J.Ewel (eds.). Ecosystems of Florida. University of Central Florida Press, Orlando, Florida. Richardson D., R.P. Wunderlin, and B.F. Hansen. 1991. University of South Florida Ecology Research Area Checklist of Vascular Plants. Scott, T.M., K.M. Campbell, F.R. Rupert, J.D. Arthur, T.M. Missimer, J.M. Lloyd, J.W. Yon, and J.G. Duncan. 2001. Geological Map of the State of Florida. Florida Geological Survey and Department of Environmental Protection. Tallahassee, Florida. (http://sofia.usgs.gov) Scott, T.M. 2001. Text to Accompany the Geological Map of Florida, Open-File Report 80. Florida Geological Survey. Tallahassee, Florida. (http://sofia.usgs.gov)
111 Southeast Regional Climate Center (SERCC). Period of Record Monthly Climate Summary. Period of Record: 3/25/1900 to 3/31/2004. Tampa WSCMO ARPT, Florida (088788). (firstname.lastname@example.org). Stiling, P. 1999. Ecology Theories and Applica tions Third Edition. Prentice Hall, Upper Saddle River, New Jersey. The Nature Conservancy. 1996. Vegetation Mon itoring in a Management Context. Text for A Workshop Coordinated by The Nature Conservanc y Cosponsored by the U.S.Forest Service. Webb, S.D. 1990. Historical Biogeography. p. 70100. In : Meyers, R.L. and J.J.Ewel (eds.). Ecosystems of Florida. University of Central Florida Press, Orlando, Florida. Winsberg, M.D. 2003. Florida Weather Second Edition. University Press of Florida, Gainesville, Florida. Wunderlin, R.P. 1998. Guide to the Vascular Plan ts of Florida. University Press of Florida, Gainesville, Florida. Wunderlin, R.P. and B.F. Hansen. 2000. Flora of Florida Volume 1 Pteridophytes and Gymnosperms. University Press of Florida. Gainesville, Florida. Wunderlin, R.P. and B.F. Hansen. 2003. Guide to the Vascular Plants of Florida, 2nd ed. University Press of Florida, Gainesville, Florida. Wunderlin, R.P. and B.F. Hansen. 2005. Atlas of Florida Vascular Plants (http://www.plantatlas.usf.edu/) [S .M. Landry and K.N. Campbell (application development), Florida Center for Co mmunity Design and Research.] Institute for Systematic Botany, University of South Florida, Tampa, Florida. Supplemental references used for identification were Chafin (2000); Dressler et al. (1991); Godfrey (1988); Godfrey and Wooten (1979, 1981); Hitchcock (1951); Lellinger (1985); Nelson (1994, 1996, 2000); Taylor (1992, 1998); Tobe et al. (1998); USDA/SCS (1974).
113 Appendix A: SUMMARY OF RESEARCH ACTIVITIES ON THE ECOLOGICAL RESEARCH AREA (Updated December 2000) Ecoarea Research Committee, Go rdon A. Fox, Gary Huxel, Earl D. McCoy, and Henry R. Mushinsky Graduate Degrees granted based upon resea rch at the Ecological Research Area Adam S.R. 1978. Populations studies and ecology of a native population of Peromyscus gossypinus and an introduced population of Peromyscus floridanus on Buck Island, Florida. M.S. Thesis, L. Brown, Major Professor. Carson, G.E. 1982. The reproductive biology of the cotton rat (Sigmodon hispidus) in central Florida. M.S. Thesis, L. Brown, Major Professor. Colson, J. 2003. M.S. Studies of paternity in the gopher tortoise. M.S. Thesis, H. Mushinsky and E. D. McCoy, Major Professors. Richardson, D.R. 1985. Allelopathic effects of species in the sand pine scrub of Florida. Ph.D. Dissertation G.B. Williamson and R.P. Wunderlin, Major Professors. Macdonald, L.A. 1986. The diet of the gopher tortoise, Gopherus polyphemus, in a sandhill habitat in Central Florida. M.S. Thesi s, H.R. Mushinsky, Major Professor. Williams, D. 1987 The effects of fire on the a bundance of small mammals. M.S. Thesis, E. D. McCoy and H.R. Mushinsky, Major Professors. Linley, T.O. 1987 The reproductive effort and output of Gopherus polyphemus in Central Florida. M.S. Thesis, H.R. Mushinsky, Major Professor. Witz, B. 1987 Insect pygidial gland secretions as a reptile predatory deterrent. M.S. Thesis, H.R. Mushinsky, Major Professor. Rebertus, A. 1987 The effect of fire on wood y vegetation of the sandhills. G.B. Williamson, Major Professor (LSU, Baton Rouge). Kaczor, S. 1988 The effect of gopher tort oise (Gopherus polyphemus) disturbance on the herbaceous vegetation and microenvironment of the sandhill. M.S. Thesis D. Hartnett and R. Wunderlin, Major Professors, Weidenhamer, J. 1988 Allelopathic effects of Blygonella myriaphyllan and Cladonia leporina Ph.D. Dissertation, J. T. Romeo, Major Professor. Wilson, D. S. 1990 Home range, activity, and burrow use of juvenile gopher tortoise (Gopherus polyphemus) in a central Florida population. M. S. Thesis. H.R. Mushinsky and E. D. McCoy, Major Professors.
114 Appendix A: (Continued) Witz, Brain W. 1994. The foraging behavior and physiological ecology of Cnemidophorus sexlineatus L. (Squamata:Teiidae) in a Florida sa ndhill habitat. Ph.D. Dissertation, E. D. McCoy and H.R. Mushinsky. Major Professors. Chernov, Kimberly R. 1994. Genetic structure of a population of the fungus Basidiobolus as revealed by analysis of anonymous DNA sequen ces. M. S. Thesis, Dr. Bruce Cochrane, Major Professor. Connor, Kevin M. 1996. Homing behavior and orientation in the gopher tortoise, Gopherus polyphemus. M. S. Thesis, H.R. Mushinsky and E. D. McCoy, Major Professors. Hayes, Keeney L. 1996. Visual cliff response and pitfall trap avoidance behavior of the six-lined racerunner, Cnemidophorus sexlineatus. M. S. Thesis, H.R. Mushinsky Major Professor. Wilson D. S. 1996 Nest site selection in the st riped mud turtle, Kinosternon baurii. Ph.D in Biology Advisors: Drs. Henry R. Mushinsky and Earl D. McCoy. Nelson, Rex T. 1998 Analysis of phenotypic and genetic variation in the fungal genus Basidiobolus. Advisor: Dr. Bruce Cochrane Stilson, T. A. 2001 The diet of the juvenile gopher tortoise. M. S. Thesis, E, D. McCoy and H. R. Mushinsky, Major Professors. Published reports of research conducte d on the Ecological Research Area All publications are in peer reviewed primary literature. Brown, L. N. 1971. Breeding biology of the pocke t gopher (Geomys pinetis) in southern Florida. American Midland Naturalist 85: 45-53. Brown, L. N. 1972. Mating behavior and life history of the sweetbay silkmoth (Callosamia carolina). Science, 176: 73-75. Brown, L. N. 1972. Life history of Florida moths. Florida Field Naturalist, 45:100-105. Hickman, G. C., and L.N. Brown. 1973. Moun d-building behavior of the southeastern pocket gopher (Geomys Pinetis). Journal of Mammalogy., 54: 786790. Hickman, G. C., and L.N. Brown. 1973. Pattern and rate of sound extension of southeastern pocket gopher (Geomys pinetis). J ournal of Mammalogy 54: 971-975. Brown, L. N. 1976. A population of Satyrium liparops liparops in west central Florida. Journal of the Lepidopteran Society 30: 213. Williamson, G.B. and E.M. Black. 1981. High temperature of forest fires under pines as a selective advantage over oaks. Nature 293: 643-644. Mushinsky, H.R. 1984. Observations on the feeding habits of the short-tailed snake. Herpetological Review 16: 67-68. Mushinsky, H.R. 1985. Fire and the Florida sa ndhill herpetofauna: with special attention to responses of Cnemidophorus sexlineatus. Herpetologica 41: 333-342.
115 Appendix A: (Continued) Mushinsky, H.R. 1986. Fire, vegetation struct ure and herpetofaunal communities. Studies in Herpetology: 383-388 Mushinsky, H.R., T. A. Stilson, and E. D. McCoy. 2003. Diet and dietary preferences of the juvenile gopher tortoise. Herpetologica 59: 477-485 McCoy, Earl D. 1987. The ground-dwelling bee tles of periodically-burned plots of sandhill. Florida Entomologist. 70:31 Hartnett, D.C. 1987. Effects of fire on clonal growth and dynamics of Pityopsis graninifolia (Asteraceae) Journal of Botany 74:1737-1743. Macdonald, L.A. and H.R. Mushinsky. 1988. Foraging ecology of the gopher tortoise, Gopherus polyhemus in a sandhill habitat Herpetologica 44:345-353. Williamson, G. B. and D. R. Richardson. 1988. Bioassays for allelopathy: Measuring treatment responses with independent controls. Journal of Chemical Ecology 14:181-187. Hartnett, D. C. and D. R. Richardson. 1989. Population biology of Bonamia grandiflora (Convolvulaceae): Effects of fire on plant and seed bank dynamics. American Journal of Botany 76:361-369. Davidson, B., T. Eisner, B.W. Witz and J. Meinwald. 1989. Defensive secretions of the Carabid Beetle, Pasimachus subsulcat us. Journal of Chemical Ecology 15(6): 1689-1697. Witz, B.W. and H.R. Mushinsky. 1989. Pygi dial secretions of Pasimachus subsulcatus (Coleoptera: Carabidae) deter predation by Eu meces inexpectatus (Squamata:Scincidae). Journal of Chemical Ecology 15(3): 1033-1044. Weidenhamer, J. D., D. C. Hartnett, and J. T. Romeo. 1989. Density-dependent phytotoxicity: Distinguishing resource competition and allelopathic interference in plants. Journal of Applied Ecology 26:613-624. Hartnett, D. C. and D. M. Krofta. 1989. Fifty-fi ve years or post-fire succession in a southern mixed hardwood forest. Bulletin of The Torrey Botanical Club 116:107-113. Rebertus, A. J., G. B. Williamson, and E. B. Mo ser. 1989. Fire induced changes in Quercus leavis spatial pattern in Florida sandhills. Journal of Ecology 77:638-650. Rebertus, A. J., G. B. Williamson, and E. B. Mo ser. 1989. Longleaf pine pyrogenicity and turkey oak mortality in Florida xeric sandhills. Ecology 70:60-70. Kaczor S. A. and D. C. Hartnett. 1990. Gophe r tortoise (Gopherus polyphemus) effects on soils and vegetation in a Florida sandhill community. American Midland Naturalist 123:100-111. McCoy, E. D. and B. W. Kaiser. 1990. Changes in the foraging activity of the southern harvester ant in response to fire. American Midland Naturalist 123:112-123. Wilson, D. S. 1991. Estimates of survival for juvenile gopher tortoises, Gopherus polyphemus. Journal of Herpetology 25(3):376-379.Witz, B.W. 1 991. Comparative ultrastructural analysis of spermatogenesis in Pasimachus subsulcatusand Pasimachus strenuus. I nvertebrate Reproduction and Development 18(3): 197-203 Wilson, D. S., H. R. Mushinsky, and E. D. McCoy. 1991. Relationship between gopher tortoise body size and burrow width. Herpetological Review 22(4):122-124. Witz, B. W., D. S. Wilson, and M. Palmer 1991. Estimating population size and hatchling mortality of Gopherus polyphemus. Florida Scientist 55(1):14-19.
116 Appendix A: (Continued) Witz, B.W., D.S. Wilson and M.D. Palmer. 1991. Distribution of Gopherus polyphemus and its vertebrate symbionts in three burrow categori es. American Midland Naturalist 126(1): 152-158. Mushinsky, H. R. and D. J. Gibson. 1991. The influence of fire periodicity on habitat structure. P. 237-259. In Habitat Structure: The Physical Arrangement of Objects in Space (S. S. Bell, E. D. McCoy, and H. R. Mushinsky, Eds.). Chapman and Hall Ltd. Mushinsky, H. R. 1992. Natural history and abundance of southeastern five-lined skinks, Eumeces inexpectatus on a periodically-burned sandhill in Florida. Herpetologica: 48:307-312. McCoy, E. D. and H. R. Mushinsky. 1992. Stud ying a species in decline:gopher tortoises and the dilemma of "correction factors". Herpetologica 48:402-407. Mushinsky, H. R. and D. S. Wilson. 1992. Seasonal occurrence of Kinosternon baurii on a sandhill in central Florida. Journal of Herpetology 26(2):207-209. McCoy, E. D., H. R. Mushinsky and D. S. Wilson. 1993. Pattern in the compass orientation of gopher tortoise burrows at different spatial scales. Global Ecology and Biogeography Letters 3:33-40. McCoy, E.D. and B.W. Witz. 1993. Population ecology of two species of Pasimachus (Coleoptera: Carabidae) in the sandhill habitat of Florida. Florida Entomologist 77: 155-163. Mushinsky, H.R. and B.W. Witz. 1993. Notes on the Peninsular Crowned Snake, Tantilla relicta, in periodically-burned habitat. Jour nal of Herpetology 27(4): 468-470. Witz, B.W. and J.M. Lawrence. 1993. Nutrient absorption efficiencies of the lizard, Cnemidophorus sexlineatus (Sauria: Teiidae). Comparative Biochemistry and Physiology 105A(1): 151-155. Mushinsky, H. R. 1993. Floridas High-Pine Sa ndhill Communities. Florida Wildlife, 47:19-23. Wilson, D. S. 1994. Tracking small animals with thread bobbins. Herpetological Review 25:1314. Mushinsky, H. R., D. S. Wilson and E. D. McCoy. 1994. Growth and sexual dimorphism of Gopherus polyphemus in central Florida. Herpetologica 50:119-128. Wilson, D. S., H. R. Mushinsky, and E. D. McCoy. 1994. Home range, activity, and burrow use of juvenile gopher tortoises in a central Florida po pulation. Pp. 147-160 in R. B. Bury and D. J. Germano, editors. Biology of North American Tortoises. National Biological Survey, Fish and Wildlife Research 13. Mushinsky, H. R. and E. D. McCoy. 1994. Co mparison of gopher tortoise populations on Islands and and the mainland in Florida. Pp. 39-47 in R. B. Bury and D. J. Germano, editors. Biology of North American Tortoises. National Biological Survey, Fish and Wildlife Research 13. Linley, T. A. and H. R. Mushinsky. 1994. Organic composition and energy content of eggs and hatchlings of the gopher tortoise. Pp. 129-138 in R. B. Bury and D. J. Germano, editors. Biology of North American Tortoises. National Biologi cal Survey, Fish and Wildlife Research 13. Witz, B.W. 1996. The functional response of Cnemidophorus sexlineatus: laboratory versus field measurements. Journal of Herpetology 30(4): 498-506. Witz. B.W. 1996. A new device for capturing small to medium sized lizards The lizard grabber. Herpetologica Review 27(3): 130-131.
117 Appendix A: (Continued) Ewert, M. A. and D. S. Wilson 1996. Seasonal variation of embryonic diapause in the striped mud turtle (Kinosternon baurii) and general considerations for conservation planning. Chelonian Conservation and Biology 2(1):43-54. Mushinsky, H. R., E. D. McCoy, and D. S. Wilson. 1997. Patterns of gopher tortoise demography in Florida. Pages 252-258 in J. Van Abbema, edito r. Proceedings: Conservation, Restoration, and Management of Tortoises and Turtles an International Conference. New York Turtle and Tortoise Society and WCS Turtle Recovery Program. Bartsch, E., J. Lawrence. 1997. Leaf size and biomass allocation in Thelypteris dentata, Woodwardia virginica, and Osmunda regalis in central Florida. American Fern Journal. 87(2):7176. Wilson, D. S. 1998. Nesting ecology of the striped mud turtle (Kinoste rnon baurii) in Central Florida. Linnaeus Fund Research Report, Chelonian Conservation and Biology 3(1):142-143. Wilson, D. S. 1998. Nest-site selection: microha bitat variation and its effects on the survival of turtle embryos. Ecology 79(6):1884-1892. Nelson, Rex T., D. Te Strake, and B. J. Cochrane 1998. The distribution of Basidiobolus in soils in the vicinity of Tampa, FL. Mycologia 90: 761-766.. Wilson, D. S., H. R. Mushinsky, and E. D. Mc Coy. 1999. Nesting behavior of the striped mud turtle, Kinosternon baurii (Testudines: Kins oternidae). Copeia. 1999(4):958-968. Wilson, D. S. 2000. Kinosternon baurii (G arman 1891), Striped mud turtle. Pages in A. G. J. Rodin and P. Pritchard, editors. Conservation Bi ology and Conservation Status of Freshwater Turtles of the World. IUCN/SCC Tortoise and Freshwater Turtle Specialists Group.
118 Appendix B: Dates of controlled burns at the USF ecoarea Compiled September 1998, Updated July 2005 Prior to 1976, burns were spotty and may have been natural fires. Data were obtained by inspection of maps by Bruce Williamson. 1968 2W burned 4/4 1971 2W burned 5/4 1976 5E, 5W, 7W, burned 1/15 1979 1E, 2E, burned 5/3 1E 1W 2E 2W 5E 5W 7E 7W burn date 1979 X X 3 May 1980 X 29 May 1981 X X X X X 10 June 1982 X 15 May 1983 X X X X X 27 May 1984 X 29 May 1985 X X 16 May 1986 X X X X X 27 May 1987 X X X X 25 June 1988 X X 15 June 1989 X X X X 16 June 1990 X X X X 12 July 1991 X X X X X X 18 July 1992 X X 30 June 1993 X X X X 20 July 1994 X X NO BURN 1995 X X X X NO BURN 1996 X X X X 2 August 1997 X X X X X X NO BURN 1998 X X X X X X 20 August (2 and 7 year plots burned one year later than schedule d) 1999 X X 28 August 2000 X X X X NO BURN 2001 X X X X X X NO BURN 2002 X X NO BURN 2003 X X X X X X 27 October (1year plots three years later than scheduled) a nd 24 November (2 and 5 year plots three and two years later than scheduled respectively ) 2004 X X NO BURN 2005 X X X X X X