Longleaf Pine / Turkey Oak Sandhill Loss in a North Central Florida Preserve, 1972-1997

Southeastern Geographer Vol. XXXXI, No. 2, November 200 1, pp. 306-3 1 1 THE CHANGING SOUTH LONGLEAF PINE / TURKEY OAK SANDHILL LOSS IN A NORTH CENTRAL FLORIDA PRESERVE, 1972-1997 Ryan R. Jensen andAnna R. Carson INTRODUCTION. Longleaf pine (Pinus palustris)/turkey oak (Quercus laevis; LLP/??) sandhills were once one ofthe most widespread ecosystems in the southeastern United States, stretching from Virginia to east Texas (Myers, 1990) until fire suppression, habitat degradation, logging, conversion to other southern pines (e.g., P. elliotii and P taeda), clearing for crops, and habitat fragmentation reduced them to about 3% oftheir previous extent (Piatt, 1998). Prior to European settlement sandhills occupied up to 37 million ha in the southeastern United States (Brockway and Outcalt, 1998). Twentieth-century losses were massive. In fact, Smith et al. (2000) estimated that, in Florida and Georgia alone, 90% ofsandhill acreage was lost in the last 60 years. Because sandhill area has decreased so greatly, maintenance is a key management goal for many nature preserves and private landowners. However, the need for regular fire, the threat of invasion from other ecosystems, including southern mixed hardwood forests and sand pine (P. clausa ) communities, and past and current landuse activities make sandhill maintenance very difficult (McCay, 2000; McCay, 2001). This study quantifies sandhill loss and ecosystem changes in a north-central Florida preserve using remotely sensed data acquired in 1972 and 1997. LLP/?? SANDHILLS. Sandhill communities occur in the temperate climate of the southeastern United States in areas of roiling terrain on nutrient-poor, deep, welldrained , white-to-yellow, sterile sands with almost no silt, clay, or organic matter (Myers, 1990). Because their soils are well drained, these communities are prime areas for development. These xeric communities contain overstories of longleaf pine with turkey oak and bluejack oak (Q. incana) in the understory. While sandhills typically have less tree species diversity than hardwood forests or other woody ecosystems, they contain more overall diversity because of an extremely species-rich herbaceous layer that contains species such as green eyes (Berlandiera subacaulis), splitbeard blustem (Andropogen ternarius), honeycomb head (Balduina angustifolia), and many others (Myers, 1990). In fact, sandhill communities are some of the most speciesDr . Jensen is Assistant Professor ofGeography and Ms. Carson is a doctoral student in the Department ofGeography, Geology, andAnthropology, Indiana State University, Terre Haute, IN 47809. E-mail: gejensen@isugw.indstate.edu and acarsonl@mymail. inastate, edu. NORTH CENTRAL FLORIDA307 Fig. 1. On left, a longleaf pine in the grass stage. At right, a longleaf pine that has begun to bolt into a tree. Photograph courtesy of Drs. Kathleen C. Parker and Albert J. Parker, University of Georgia. rich habitats outside ofthe tropics (Carter et al., 1999; Smith et al., 2000). Sandhills often have a park-like appearance because of the seemingly continuous wiregrass (Aristida beyrichiana) ground cover. Sandhills depend on regular fires (recurring every 1 to 10 years) for species reproduction and protection from invasion (Myers, 1990). Because ofthis relationship with fire, sandhill species have developed a dependence on fire that is unmatched by other tree-dominated communities in the southeastern United States. For example, longleaf pine seedlings remain in what is known as the grass stage (Fig. 1 ) for 5 to 20 years while storing large quantities of photosynthates in a deep tap root. The apical bud is embedded in the surrounding erectly displayed needles that are resistant to burning (Aber and Melillo, 1991). After a fire, the seedlings can grow as much as 1 meter in height per year. Furthermore, regular sandhill burns can create natural firebreaks to prevent the kind of cataclysmic burning seen recently in Florida. Whereas most sandhill fires once occurred naturally due to lightning strikes, most burns now are conducted as prescribed burns. To conduct a prescribed burn, landowners and managers must secure a burn permit, thereby assuming 308JENSEN AND CARSON responsibility for all burn damages including human health-related consequences. Often, the threat ofthese liabilities is enough to deter most private landowners from burning. The frequency, regularity, season, and intensity of burn can have differing effects on vegetation structure and species composition of LLP/?? sandhills. For example, the abundance and stature of deciduous oaks in sandhills may be proportional to...