Manipulating the species composition of permanent grasslands-A new approach to biodiversity experiments

The relationship between biodiversity and ecosystem functions of grasslands has received increasing attention in recent years. So far, experiments were mostly conducted in experimental grasslands. We used a different approach on permanent grassland by applying herbicides selective against either dieots or monocots. This allowed us to alter plant species composition and evenness and to obtain altered constellations of functional group abundances without deliberate introduction of new species or continued disturbance by weeding. The resulting swards were subjected to different management intensities in terms of cutting regime and fertilization. Compared to the baseline data before herbicide application, within one year, the combination of treatments, especially the herbicide application, led to a broad variety of swards with the herbicide treatment alone accounting for more than 25% of the variance in composition. We conclude that the application of specific herbicides is a method highly suitable for creating different sward types, because the swards differed significantly in species number, evenness and composition of functional groups without showing signs of disturbance, as neither the area of open soil nor the proportion of annual colonizer species increased.