Effects of conservation measures on plant diversity in cultivated grasslands in the Altmühltal (Bavaria)

Cultivation and agriculture are a dominant feature in German landscapes. Efforts to maintain and enhance biodiversity in such landscapes are often based on cooperation and contracts between land users (mainly farmers) with state nature conservation authorities. Such contracts are content of the "Vertragsnaturschutzprogramm" (VNP,"nature conservation program"), where farmers receive monetary compensation for complying with certain rules and limits regarding land management. For grasslands, rules mainly limit the time of the first mowing event and the application of fertilizer. We investigate in the Altmühltal (Bavaria, Germany) the effect of different VNP measures on plant species richness and composition compared with non-VNP grasslands. We sample vegetation data in the field and analyse the effect of delayed first mowing events and the lack of fertilizers used. Additionally, we extracted information from the database "BiolFlor" to analyse the shift of traits (e.g. floral rewards, foraging value), between the grasslands under different or no VNP contracts. We find significant differences in species richness and composition between VNP and non-VNP grasslands. We observe a shift in the plant functional traits (amount of grasses, legumes, herbs) as well as in floristic traits following the gradient of most limits (strict VNP rules) to no additional limits (the non-VNP grasslands).