Manipulating species richness of permanent grasslands - a new approach to biodiversity experiments.

The relationship between biodiversity and ecosystem services of grasslands has received increasing attention in recent years. While most of the research has so far been focussing on artificial grasslands, only few studies have examined semi-natural systems such as managed permanent grasslands. The Grassland Management Project (GRASSMAN) in Silberborn (Solling Uplands, Germany), implemented in 2008, tries to fill this gap of knowledge. Instead of sowing new grassland with different levels of species richness, permanent grassland has been manipulated by application of herbicides against a) dicots and b) monocots to alter the species richness and to obtain a new distribution of the functional groups. The resulting swards were subjected to different management intensities in terms of cutting regime and fertilisation. The combination of treatments, especially the herbicide application, led to a broad variety of grass swards. They differed significantly in species numbers, evenness and composition of functional groups.