Effects of changes in management on resistance and resilience in three grassland communities

Question: Diversification of grassland management is recommended as a tool for conservation of different taxonomic groups living in those habitats. How resistant and resilient are species-rich grasslands in terms of plant species richness and vegetation composition to short-term, small-scale perturbations caused by changes in management practice? Location: Bile Karpaty Mountains, SE Czech Republic. Methods: The experiment included the effect of six management regimes (mowing in June; mowing in September; mowing in June and September; mowing in June and high stubble left; no management; mowing in June and mulching). It was conducted in species-rich wooded grasslands in the White Carpathians Mts., Czech Republic, represented by three types of plant community: a Bromus erectus community (with high species richness and low productivity), a Molinia arundinacea community (with high species richness and high productivity), and a Calamagrostis epigejos community (with low species richness and high productivity). After 3yr, resistance was assessed, and traditional management (mowing once each year in June) was resumed; resilience was evaluated after three more years. Results: While the species-rich, unproductive Bromus community was relatively resistant to less intensive management in terms of species richness, and therefore its resilience could not be assessed, it changed substantially in terms of vegetation composition (maximum dissimilarity between control and abandoned plots was 63%). The more productive Molinia and Calamagrostis communities lost up to 37% of species due to abandonment, but not as a consequence of other changes management regimes. After the traditional management was resumed, resilience was higher in the Calamagrostis community than in the Molinia community. Vegetation composition was not affected by treatments. Conclusions: The results show that short-term abandonment causes loss of plant diversity in productive grasslands but not in less productive, species-rich grasslands in the short term. Other relaxed management regimes (e.g. high stubble and delayed mowing) were comparable with the control and can be used for a short time to increase diversity of management without an effect on plant species richness. However, further research is needed to assess the effects of these management practices when they are applied repeatedly or over the long term.