Young forests regenerating after abandonment from agriculture are common in the eastern United States and much of Europe, but the factors governing floristic composition are not well understood. We examine the interaction between land-use history, physical heterogeneity, and plant life history to gain insight into the main drivers and limiting factors acting within a specific ecosystem. Land use history and landscape structure of a section of the western Allegheny Plateau were described by point-sampling historical aerial photographs. Plant community and environmental data were collected in the field. We expected a two-phase process based on studies of primary succession in which forest species accumulate and are then sorted by a process of environmental filtering.
Results/Conclusions
Forest sites accumulated an increasingly diverse community of vascular plant species through successional time, suggesting dispersal limitation. Measures of soil character and stand development became increasingly important predictors of composition with forest age, suggesting environmental filtering. Notably, previously pastured sites accrued species at a faster rate than previously cultivated sites and the communities of valleys and slopes were distinct from those of dry ridgetop environments. By contrast, landscape metrics such as edge distance had little predictive power. Covariance of land use and landscape position (e.g. preferential cultivation of flood plains) complicates the interpretation. We conclude that re-assembly of the forest community is a gradual process potentially lasting >100 years, and is initially controlled largely by life history of individual forest species. Environmental filtering may extend much longer. It is likely that this conclusion applies to deciduous forest throughout eastern North America.