Drought impacts in Central European grasslands are buffered through biodiversity

Abstract

Since two decades, severe periods of drought combined with heat waves have impacted European ecosystems. Permanent ecosystems such as grasslands which are of large extent and of substantial economic importance have been strongly affected. Grasslands such as meadows and pastures are also highly diverse in species and plant functional types, and many of them are protected by law, e.g. within the frame of Natura 2000. Plant richness is correlated with the diversity of pollinators and so, grasslands are a main support to insect diversity in Central European cultural landscapes. Management practices differ, however, and traditional hay meadows and extensive pastures have become rare. They are increasingly replaced by frequently mown and fertilized species poor grasslands that exhibit a series of ecosystem disservices such as pollution of aquifers by nitrogen and release of carbon from soils.

Here, we assess the role of biodiversity for the maintenance of grassland ecosystem functioning. Experimental approaches are combined with field work and remote sensing to monitor the responses to drought and the contribution of biodiversity to resilience and stability. Extreme periods of drought are causing a series of effects in community assemblages and related processes.

Invasibility of communities is generally controlled by species richness of established plants. Drought, does not enhance invasion processes in grasslands (in contrast to long periods of heavy rain), but it modifies species composition and increases beta-diversity within short distances, resulting in a higher spatial heterogeneity of grasslands.

The stability and resistance of grasslands towards drought is found to be strongly correlated with biodiversity. The more species are established, the less negative effects of extreme climatic events can be observed. This meanst that if biodiversity is once lost, also the ecosystem services of grasslands to secure for instance food production are threatened.

Furthermore, we can show with remote sensing (Sentinel 2, Copernicus) detailled responses of grasslands in protected areas during periods of drought, indicating the need of efficient monitoring techniques to safeguard adaptive management strategies in nature reserves. We suggest consequences for the network of protected areas in face of climate change. Grasslands play an eminent role in Central European protected areas. Their contribution to societal interests such as nature conservation, recreational activities, agriculture, carbon sequenstration, flood and erosion control, slope stability etc. must be maintained. This requires and extension of protection schemes as it is requested by the CBD and the European Biodiversity Strategy for 2030. Remote sensing combined with ecological assessments of grassland biodiversity and functioning will be needed for sustainable nature-based solutions.