Landscape structure as an indicator of biodiversity: matrix effects on species richness

Sustainable conservation management in cultivated landscapes urgently needs indicators that provide quantitative links between landscape patterns and biodiversity. As a contribution to this aim, the influence of the matrix surrounding managed grassland sites on species richness of ants, wild bees and vascular plants was investigated at two different scales (50 and 200 m radius). In addition, patch variables describing habitat quality were included in the analyses. Species richness of the three taxa was not significantly inter-correlated. Multiple linear regression analysis revealed significant predictor variables for the species richness of the different taxa at both matrix scales. The variation of the matrix radius had no impact on the variance explanation of the regression models. The degree of variance explained by the regression models varied between taxa (bees>plants>ants). Moreover, the predictive variables were different for the taxa, with the regression model for wild bees including both patch and matrix variables, that for plants richness including patch variables only, and that for ants including matrix variables only. We conclude that landscape diversity and percentage cover of certain land-use types might serve as useful indicators for species richness at the landscape scale. However, the specific response patterns revealed in our study suggest that a variety of taxa must be included in this type of approach.