Land-use legacies in a central Appalachian forest: differential response of trees and herbs to historic agricultural practices

Question: Are contemporary herb and tree patterns explained by historic land use practices? If so, are observed vegetation patterns associated with lifehistory characteristics, soil properties, or other environmental variables? Location: Southeastern Ohio, USA. Methods: Using archival records, currently forested sites were identified with distinct land use histories: cultivated, pasture (but not plowed), and reference sites which appear to have never been cleared. Trees were recorded by size and species on twenty 20m 20m plots; percent cover was estimated for each herb species in nested 10m 10m plots. Environmental characteristics were noted, and soil samples analysed for nutrient availability and organic matter. Nonmetric multidimensional scaling ordination was performed separately on both tree and herb datasets to graphically characterize community composition among plots. Life-history traits were investigated to explain observed compositional differences. Results: Vegetation patterns were explained by current environmental gradients, especially by land-use history. Cultivated and pasture sites had similar tree composition, distinct from reference sites. Herb composition of pasture and reference sites was similar and distinct from cultivated sites, suggesting the ‘tenacity’ of some forest herbs on formerly cleared sites. Tilling removes rhizomatous species, and disfavors species with unassisted dispersal. These life-history traits were underrepresented on cultivated sites, although ant-dispersed species were not. Conclusions: Historic land-use practices accounted for as much variation in species composition as environmental gradients. Furthermore, trees and herbs responded differently to past land-use practices. Life-history traits of individual species interact with the nature of disturbance to influence community composition.