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 f orest edge, with peak abundance at different spatial positions relative to the edge. Principal components analysis resulted in three axes which explai ned a total of 63.2% of the variation within the data set. The first two PC A axes were related to distance to the forest edge. The third separated plo ts into those that were dominated by Solidago canadensis, and those that we re dominated by Solidago juncea. All population- and community-level attrib utes varied along the edge gradient. Species richness, Shannon-Wiener diver sity, and total percent cover increased from the forest to the edge, with s light declines 60 m from the edge in the field. Among-plot heterogeneity wa s 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 restr icted to the edge. Most population- and community-level attributes showed e dge responses on both sides of the edge. This emphasizes the need to study edges as gradients that include both disturbed and undisturbed habitats.