The potential of land-use extensification as grassland restoration tool

1. Land-use extensification could be a straightforward restoration strategy to reverse grassland degradation. However, the potential of extensification to achieve comprehensive restoration goals is still unclear and may depend on site-specific conditions.

2. We used a land-use reduction experiment (45 grasslands within three German regions) to measure extensification response for a broad set of parameters related to abiotic conditions, taxonomic and functional diversity and community composition of plants and soil microbes, and ecosystem functioning and services. For each parameter, we analysed the variation in extensification response between regions and along a gradient of pre-extensification land-use intensity. To evaluate extensification effects we applied a new framework that provides a comprehensive perspective on ecosystem restoration by incorporating multiple restoration goals. The framework assigns indicators to each goal and sets targets against which goal achievement can be assessed.

3. After three years of extensification, we found notable response in light and microsites availability along with clear effects on plant community taxonomic and functional composition, probably as a result of the altered biomass removal regime in extensified plots, but only weak effects on soil properties and nutrient availability paired with missing effects on soil microbes and soil-related functions. For some parameters, extensification effects varied strongly between regions, along the gradient of pre-extensification land-use intensity or were mediated by an interaction of both. The observed pattern of effects suggests a temporal ordering of extensification response cascading from abiotic conditions, taxonomic and functional diversity and composition to ecosystem functions and services.

4. Synthesis and applications. Our results indicate that short-term extensification measures in grassland may be not particularly efficient in achieving comprehensive restoration goals. These findings call for policies that should be designed to promote a long-term reduction in grassland management intensity on constant areas, rather than short-term measures such as the ‘Eco-schemes’ implemented in current European Union’s Common Agricultural Policy. Furthermore, the results demonstrate the outstanding importance of context in predicting extensification response and in identifying circumstances where extensification may be an appropriate measure.