Floristic Inventory of the Altamaha River Floodplain
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FLORISTIC INVENTORY OF AN ALTAMAHA RIVER FLOODPLAIN AREA by HOLLY HOLLAND LUBER (Under the Direction of David Giannasi) A floristic inventory was documented for an Altamaha River floodplain forest and associated upland communities. The study area, located in the lower Altamaha River watershed, includes parts of Bullard Creek Wildlife Management Area and Griffin Ridge Wildlife Management Area. Information on climate, geology and physiography, hydrology, and human history and disturbance of the study site precedes a discussion of the plant communities. Communities recognized include floodplain forest, flatwoods, sandhills, isolated wetlands, and aquatic. A total of 375 species representing 91 families and 233 genera were collected and appear in an annotated checklist. Five species listed as unusual or of special concern in the state of Georgia occur at the study site. A total of 303 county records for Jeff Davis and Long Counties were collected. INDEX WORDS: Floristics, Altamaha River, Coastal Plain, Floodplain Forest FLORISTIC INVENTORY OF AN ALTAMAHA RIVER FLOODPLAIN AREA by HOLLY H. LUBER B.S., Northern Arizona University, 1997 A Thesis Submitted to the Graduate Faculty of The University of Georgia in Partial Fulfillment of the Requirements for the Degree MASTER OF SCIENCE ATHENS, GEORGIA 2002 2002 Holly H. Luber All Rights Reserved FLORISTIC INVENTORY OF AN ALTAMAHA RIVER FLOODPLAIN AREA by HOLLY H. LUBER Approved: Major Professor: David Giannasi Committee: Jim Affolter Rebecca Sharitz Electronic Version Approved: Gordhan L. Patel Dean of the Graduate School The University of Georgia August 2002 ACKNOWLEDGEMENTS I would like to acknowledge several people for their support throughout this project. First, I owe the success of this project to my husband, George Luber, who accompanied me on every collecting trip. Every stage of this endeavor would not have been possible without his support, patience, and encouragement. I would also like to thank Dr. David Giannasi for his suggestions and guidance throughout my graduate study. He helped to keep things simple with the end in sight. I would also like to thank my committee members, Dr. Jim Affolter and Dr. Rebecca Sharitz, for their time and suggestions. I owe a special thanks to Dr. Wilbur Duncan for his help in making plant identifications. Last, but certainly not least, I would like to thank my friends, Gretel Guest, Elissa Totin and Lisa Kruse, for their help and support during the most important times. iv TABLE OF CONTENTS Page ACKNOWLEDGEMENTS............................................................................................... iv CHAPTER 1 INTRODUCTION..................................................................................................1 2 SITE DESCRIPTION…………………………………………………………….4 3 HUMAN HISTORY AND DISTURBANCE…………………………………..16 4 METHODS……………………………………………………………………...25 5 RESULTS AND DISCUSSION ..........................................................................26 6 SUMMARY .........................................................................................................39 REFERENCES CITED…………………………………………………………………..40 APPENDICES A ANNOTATED CHECKLIST OF THE VASCULAR FLORA OF AN ALTAMAHA RIVER FLOODPLAIN AREA ............................................................43 B MAP OF BULLARD CREEK WMA...........................................................................54 C MAP OF GRIFFIN RIDGE WMA ...............................................................................55 D CLIMATE DATA FOR GLENNVILLE, GA ..............................................................56 E CLIMATE DATA FOR SURRENCY, GA ..................................................................57 v CHAPTER 1 INTRODUCTION This thesis presents the results of a floristic inventory conducted in two floodplain forests along the Altamaha River. Located in the southeastern Coastal Plain of Georgia, the Altamaha River begins at the confluence of the Oconee and Ocmulgee Rivers near Hazelhurst, Georgia and flows 137 miles (220 kilometers) southeasterly before draining into the Atlantic Ocean. The Altamaha River watershed is the third largest on the eastern seaboard of the United States and drains 7,760 square miles (19,4000 square kilometers) of Piedmont terrain and 11,520 square miles (28,800 square kilometers) of Coastal Plain, approximately one-quarter of the state (Georgia Department of Natural Resources, Coastal Resources Division, 1997). Georgia, the largest state east of the Mississippi River, ranks seventh in vascular plant diversity in the continental United States (Villa-Lobos, 1999). The Altamaha watershed boasts the highest documented number of rare plants, animals, and natural community occurrences in the state of Georgia. Of the approximately 140 rare plants and animals occurring here, 15 are federally listed as threatened or endangered, 17 are state listed and are considered globally rare or imperiled (Georgia Department of Natural Resources, Coastal Resources Division, 1997). Four extremely rare plants occur nowhere else in the world but Georgia and have been documented in the Altamaha River corridor. They are hairy rattleweed (Baptisia arachnifera), Radford’s dicerandra (Dicerandra 1 radfordiana), Georgia plume (Elliottia racemosa), and cutleaf beardtounge (Penstemon dissectus). Among species native to the river basin the most well known and fascinating is Franklinia altamaha, named in honor of Benjamin Franklin. This rare flowering plant was first seen by William Bartram in 1765 and has not been seen in its natural environment since 1803 (Villa-Lobos, 1999). The incredible biological diversity of the lower Altamaha River watershed is important to both the economic and ecological health of the surrounding area and the state as a whole. The river and its surrounding lands provide critical habitat and food sources needed for the survival of a variety of plants and animals. The ecological value of the river has prompted The Nature Conservancy (TNC) of Georgia to make this area a conservation priority. TNC hails the Altamaha River as one of 75 remaining “Last Great Places” worldwide (Villa-Lobos, 1999). In 1991, TNC established the Altamaha River Bioreserve on 1.2 million acres of the lower River Basin (Villa-Lobos, 1999). Ultimately, The Nature Conservancy would like to protect the entire ecosystem/river corridor as a bioreserve rather than a multitude of small preserves. Intense research, including field inventory, is necessary to understand the diversity and value of the Altamaha River ecosystem. The primary purpose of this study is to document the vascular flora occurring in floodplain forests and associated habitats along the Altamaha River. The Altamaha River is a typical southeastern alluvial river and swamp system (Wharton, 1978). Plant communities found in the study site include floodplain forest, flatwoods, sandhills, and isolated wetlands such as cypress ponds, cypress domes, and bay forest. This study site was selected not only because of its uniqueness and rich history, but also because this 2 area is especially underrepresented in the University of Georgia herbarium collection. Therefore, this study seeks to provide a better understanding of the diversity of floodplain forest ecosystems along the Altamaha River. A floristic inventory of a unique area such as this will contribute to our knowledge of the flora of Georgia. The following chapters present the results of this floristic inventory. Chapter 2 describes the study site focusing on its location, climate, soils, physiography and geology, and hydrology. Chapter 3 focuses on the human influences on the Altamaha region with an emphasis on disturbances and modifications of the natural environment throughout history and prehistory. Chapter 4 details the field and herbarium methods used in this study. Chapter 5 presents the results of this floristic inventory, focusing on the description of plant communities found as well as plants of special interest encountered during this research. The discussion section compares this field site with others in the region with respect to diversity of plant species and plant communities. Chapter 6 concludes this thesis with a discussion of the significance of this research for the understanding and preservation of this rich and valuable natural resource. 3 CHAPTER 2 SITE DESCRIPTION The Study Area This floristic inventory was conducted in two Georgia Wildlife Management Areas in the Altamaha River watershed. Located in southeastern Georgia, the lower Altamaha River watershed covers both the Upper and Lower Coastal Plain physiographic provinces (see Figure 2.1). The Altamaha River’s origins in the southern Piedmont classify it as an alluvial or brown water river. The Altamaha Basin covers an area of 3,234 square miles, all within the state of Georgia (Georgia Department of Natural Resources, Coastal Resources Division, 1997). Two sites, one at the confluence of the Oconee and Ocmulgee Rivers and one approximately sixty miles, or halfway, downstream, were selected to conduct botanical collections. Both sites were located in Georgia Department of Natural Resources Wildlife Management Areas (WMA) in the upper portion of the river corridor. The upper river corridor was chosen for the following reasons: 1) Many areas along the river corridor south of the study site are abandoned rice fields or salt marsh. Hence, species diversity is expected to be low in these areas. 2) The Nature Conservancy (TNC) has purchased several tracts of land along the river and has recently