Extensive grassland-use sustains high levels of soil biological activity, but does not alleviate detrimental climate change effects

Abstract Climate change and intensified land use simultaneously affect the magnitude and resilience of soil-derived ecosystem functions, such as nutrient cycling and decomposition. Thus far, the responses of soil organisms to interacting global change drivers remain poorly explored and our knowledge of below-ground phenology is particularly limited. Previous studies suggest that extensive land-use management has the potential to buffer detrimental climate change impacts, via biodiversity-mediated effects. According to the insurance hypothesis of biodiversity, a higher biodiversity of soil communities and thus an elevated response diversity to climate change would facilitate a more stable provisioning of ecosystem functions under environmental stress. Here we present results of a two-year study investigating, at fine temporal resolution, the effects of predicted climate change scenarios (altered precipitation patterns; passive warming) on three grassland types, differing in land-use intensity, soil biological activity, and in resilience. We show that future climate conditions consistently reduced soil biological activity, revealing an overall negative effect of predicted climate change. Furthermore, future climate caused earlier and significantly lower peaks of biological activity in the soil. Land-use intensity also significantly decreased soil biological activity, but contrary to general expectations, extensive land use did not alleviate the detrimental effects of simulated climate change. Instead, the greatest reduction in soil biological activity was observed in extensively-used grasslands, highlighting their potential vulnerability to predicted climate change. To assure high levels of biological activity in resilient agroecosystems, extensive land use needs to be complemented by other management approaches, such as the adoption of specific plant species compositions that secure ecosystem functioning in a changing world.