The influence of geomorphological heterogeneity on biodiversity I. A patch-scale perspective

Landscapes composed of spatially heterogeneous abiotic conditions should provide a greater diversity of potential niches for plants and animals than do homogeneous landscapes. We tested this hypothesis in a deciduous forest ecosystem in the northeastern United States. We created an index that summarizes the collective variation in terrain and soil properties in 2-ha study plots. We measured woody plant species richness and diversity in 20 study plots that had high geomorphological heterogeneity and 20 plots that had low geomorphological heterogeneity. The richness and diversity of trees and shrubs were significantly higher in sites with high geomorphological heterogeneity than in sites that exhibited little change in terrain or soil conditions. Variation in aspect and soil drainage were especially important predictors of biotic diversity. Our results demonstrate an intimate association between abiotic and biotic diversity and have significant implications for long-term conservation strategies.