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In the present study, we examined the effect of shrub encroachment in temperate semi-natural grasslands on plant species diversity. We tested the hypothesis that an initial shrub encroachment leads to enhanced habitat heterogeneity and thereby to a higher diversity. In a calcareous grassland near Göttingen (Germany) we analysed the effect of shrub encroachment on the species richness in 30, 100 m 2 plots each with 10 subplots of 1m 2 size. The 30 main plots belonged to six different shrub encroach�ent classes. A descriptive correlative gradient analysis of shrub invaded grasslands and their species nu�ber of flowering plants was performed. Within the 30 plots of different shrub encroachment a total of 203 plant species were recorded. The mean �1-diversity (level of subplots), mean �2-diversity (level of plots) as well as the �3-diversity (level of shrub encroachment classes) have their highest values at �ediu� shrub invaded sites. This finding is in line with our hypothesis of a hu�p�back relation between shrub encroachment and species richness, and can be explained by the increased habitat heterogeneity. However, Detrended Correspondence Analysis (DCA) emphasized the importance of the present vegetation composition for species richness. The dominance of highly competitive, clonal-growing grass species is accompanied by low diversity swards with a lower facilitation of shrub establish�ent. �pecies accu�ulation curves highlight the benefit of shrub encroach�ent for ��(landscape-) diversity. This result emphasises the importance of habitat heterogeneity for biodiversity and, therefore, nature conservation.

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Recent biodiversity experiments using sown plant communities suggest a positive effect of plant species diversity on ecosystem functioning and resource use. However, are these experimental results applicable to agriculturally managed grassland? We analysed vegetation structure and light interception in managed grassland in which species composition had been manipulated by herbicides. We expected the functionally more diverse plots (grasses and forbs in equal amounts) to better intercept the light than plots containing more than 90% grasses due to an optimal arrangement of leaves in space. However, management (fertilization and mowing regime) had a much stronger influence on structure and light interception than plant species composition.