Adaptation of plant functional group composition to management changes in calcareous grassland

It is the aim of plant functional research to generate general rules of species assembly and species reactions based on plant functional traits. Here we determined plant functional groups that are important with regard to land use types (grazing, mowing, mulching, burning, abandonment) and looked for mechanisms leading to changes in species composition after management changes in calcareous grasslands. To filter out the set of traits which best described the variation in plant composition along the studied land use gradient and to identify functional groups we chose an iterative three-table ordination method. We included traits related to persistence as well as traits describing the germination niche of a plant. To gain insight into underlying mechanisms which led to differing importance of these plant functional groups at different management regimes we investigated shifts in dominance of the identified functional groups at eight management regimes using long-term vegetation data of a site which was grazed before the onset of different management regimes in 1974. Ongoing unidirectional changes in cover of the four determined functional groups at most of the treatments indicated that even after almost 30 years new equilibria of functional group composition were still not reached. The study showed that other management treatments but grazing and mowing led to changes in functional group composition, which were mainly driven by increasing dominance of a highly competitive species group.