Changes in community and population responses across a forest-field gradient

The ground-layer vegetation of a forest-old field edge gradient was sampled to determine the effects of the edge on spatial patterns of plant species and community attributes. Species showed individualistic responses to the forest edge, with peak abundance at different spatial positions relative to the edge. Principal components analysis resulted in three axes which explained a total of 63.2% of the variation within the data set. The first two PCA axes were related to distance to the forest edge. The third separated plots into those that were dominated by Solidago canadensis. and those that were dominated by Solidago juncea. All population and community-level attributes varied along the edge gradient. Species richness, Shannon-Wiener diversity, and total percent cover increased from the forest to the edge, with slight declines 60 m from the edge in the field. Among-plot heterogeneity was higher at the edge than in either the forest or the field. Exotic species had peak abundance within 20 m of the edge inside the forest and are restricted to the edge. Most population and community-level attributes showed edge responses on both sides of the edge. This emphasizes the need to study edges as gradients that include both disturbed and undisturbed habitats.