PARENT SESSION
Oral Session #59: Conservation Ecology: Terrestrial Biodiversity. Presiding: K. Schulz.
Thursday, August 9, 2001. 8:00 AM to 12:15 PM. Madison Ballroom D.
Microhabitat of two Florida scrub endemic plant species with comparisons to their widespread congeners.
Maliakal, Satya1,2, Menges, Eric2, Denslow, Julie1,3, 1 2 3
ABSTRACT- Species restricted to small ranges and specific habitats may be more highly specialized on narrow microhabitats than co-occurring species that are more broadly distributed. We addressed this hypothesis by comparing microhabitats of two pairs of congeners that differ in geographic range and habitat specificity and co-occur in the same habitat type, Florida rosemary scrub. We characterized the microhabitats of two Florida scrub endemic species, Polygonella basiramia and Lechea cernua, both predominantly restricted to open sand gaps in rosemary scrub, in comparison to random points in rosemary scrub habitat. We also compared microhabitats of P. basiramia and L. cernua with their widespread congeners, Polygonella robusta and Lechea deckertii, that co-occur in rosemary scrub, but also occur throughout Florida in sandy habitats such as sandhills, oak scrub, and open scrubby flatwoods. Plants of both endemics occur in microhabitats with significantly greater distances from dominant shrubs, less litter cover and more open sand than random points in rosemary scrub. Microhabitats of the two widespread species are farther from dominant shrubs and have less litter cover and more open sand than random points, but have significantly more litter cover and less open sand than microhabitats of the two endemic species. Our data suggest that P. basiramia and L. cernua are specialized to the open sand microhabitats that characterize their preferred habitat, Florida rosemary scrub. Microhabitat specialization may limit the distribution of these rare species.
KEY WORDS: microhabitat, rare species, habitat specialization, Florida scrub