Session

With varying environmental conditions at the edges of habitat patches, due to and in concert with edge effects, the community composition should differ as well. This should lead to a peak in small-scale beta diversity across boundaries between habitat patches. So far there is, however, not much research on this fundamental pattern conducted and no unifying model has been formulated. Here, we present such a conceptual model on beta diversity across boundaries, derive patterns of underlying environmental parameters and responding functional traits, and test this framework on plant diversity at crop field – dry grassland boundaries in two German landscapes. We surveyed the vegetation and sampled soil parameters along twenty transects, extending approximately 30 m into both habitats. Ecological indicator values and species functional traits were also assessed. Across the boundary, we found a peak for plant beta diversity (for the turnover component, not nestedness) and a steeper gradient than in adjacent habitat interiors for most tested environmental parameters, indicator values and plant species traits. This confirms our theoretical framework. In our study, the peak of beta diversity was due to a replacement of species (turnover), not to additional (or missing) species without replacement (nestedness). In the landscape, visible boundaries are reflecting the underlying abiotic conditions, and are reflected by the deriving species functional traits. We provide a unifying model for the small-scale pattern of beta diversity across boundaries between different habitat types here. As the peaking beta diversity at boundaries increases the species diversity at the landscape level, landscape heterogeneity should be promoted for biodiversity conservation.