Combined effects of land-use type and climate change on soil microbial activity and invertebrate decomposer activity

Land-use and climate change are two of the key forces driving soil organisms’ activity and thus the ecosystem functions they provide. However, potential interactive effects of climate change and different land-use types on soil biological activity still remain unclear. Here, we studied soil biological activity in a large-scale field experiment initiated in 2014 in central Germany with two levels of input intensity (conventional versus organic treatment) and two climate scenarios (ambient climate versus “projected climate”, i.e., increased temperature by +0.55 °C and altered rainfall patterns across seasons). We measured soil microbial activity and invertebrate decomposer feeding activity across two years (2rd and 3rd year after establishment) in three-week intervals. Both soil biological activity measures were used as proxies for decomposition processes. Interactive effects of climate change and land-use types were not significant in the present study. Our results show that the projected climate reduced soil invertebrate decomposer activity by −16%, while soil microbial activity was not impaired. This suggests that even a slight increase in temperature together with a shift in precipitation patterns, can induce a significant reduction in soil functions like organic matter decomposition and nutrient cycling. Soil microbial (−9.6%) and invertebrate decomposer activity (−22%) were significantly lower in organic treatment compared to conventional treatment, which might be due to higher soil organic carbon and nutrient concentrations in conventional treatment in the short term. These findings highlight the need to better understand the main drivers of short- and long-term effects on belowground functioning to develop sustainable management strategies for healthy soils in a changing climate.