Response of weed flora to large-scale landscape factors
Abstract: Weed communities were investigated in a large-scale agricultural region in northernGermany. Multivariate analysis was used to determine how species richness and weedcomposition respond to landscape structure at different spatial scales (namely 100m–2500m).Records of species numbers were accompanied by high variance. There was a significantcorrelation between landscape structure and species richness. However, the impact of landscapecomplexity on species richness was relative low and mostly scale independent. Landscapecharacteristics within a 100m circle provided significantly the best explanation of species richnesson conventional plots. The percentage of explained variation in species composition throughlandscape variables ranged from 3% to 5%. Local site effects explained a considerably higherpercentage of variation in species composition. Ellenberg indicator values and soil type explained14% of variation. These results indicate that it is difficult to relate weed species communities tolandscape characteristics if the landscape is relatively homogenous and large-scaled. Neverthelessthere seems to be a stronger effect of landscape characteristics on species if diversity exists at asmall spatial scale.