Ecological Site Classification of Florida Keys Terrestrial Habitats

Abstract

Site and vegetation characteristics were examined in 113 Florida Keys locations that had been undisturbed for at least 50 years. Detrended correspondence analysis (DECORANA) indicated that Keys vegetation was arranged along two major environmental gradients: an elevational gradient within islands, and a geographic gradient associated with position along the NE-SW trending island chain. Both were complex gradients, with soil depth and type, periodicity of tidal inundation, ground water depth and salinity, climate, and geological substrate as potential contributing factors. Two-way indicator species analysis (TWINSPAN) was used to divide the samples into 14 major groups on the basis of plant species composition. Finally, the TWINSPAN classification was modified to recognize 13 Ecological Site Units which were homogeneous in important site factors as well as vegetation characteristics. Plant species diversity increased from intertidal to upland site units, while canopy height, basal area, and fine litter production increased both upslope and downslope of the supratidal units.