Spatial components of biotic diversity in landscapes of Georgia, USA

Traditional measures of species diversity and spatially-explicit measures of landscape diversity (derived from Romme 1982) are used to compare biotic diversity in six landscapes across Georgia, USA; two each from the Appalachian Highlands, Piedmont, and Coastal Plain. Species richness and evenness of plots generally increased from the Coastal Plain to the Appalachian Highlands. Community richness, landscape contrast, and landscape heterogeneity increased from the Appalachian Highlands to the Coastal Plain, opposite the gradient of topographic complexity. Coastal Plain landscapes possessed greater contrast and heterogeneity than landscapes in the other two physiographic provinces. This high level of landscape diversity is interpreted as a response to two factors: the increased role of human activity in shaping landscape structure, and the increased range of soil moisture regimes encountered in the sand-rich substrates of the Coastal Plain (from permanently flooded hydric communities to well drained xeric uplands only a few meters higher in elevation).