Global change affects the activity of soil organisms, which are responsible for several ecosystem functions and services in terrestrial ecosystems. However, we know remarkably little about potential interactive effects of global change drivers on the functioning of ecosystems. Here we study the interaction of two major global change drivers: land-use and future climatic conditions, simulated by altered precipitation regimes (reduction in summer, addition in spring and fall) and warming. The land-use types included intensively and extensively managed grasslands, as well as conventional and organic farmlands. Feeding activity of soil animals was surveyed every three weeks over a two year period using the bait lamina test, as a rapid ecosystem assessment method to obtain high temporal resolution in soil responses.
We expected climate change to shift the magnitude and phenology of soil animal feeding activity by increasing activity in earlier and later times in the growing season and by reducing activity during summer months. Furthermore, we expected that the strength of climate change effects is depending on the management intensity (i.e. land-use type). Climate change effects should be more pronounced in farmlands than in meadows, in conventional than in organic farming, and in intensively than in extensively managed grasslands.
Our results show that the future climate effect on soil animal feeding activity strongly depended on the land-use treatment. Future climatic conditions reduced soil animal feeding activity most of the year; however, the magnitude of the effect depended on the season. In addition, in the early growing season, future climatic conditions resulted in higher feeding activity.
Intensively and extensively managed grasslands as well as conventional and organic farmlands differed significantly in their belowground activity. Activity was highest in extensively managed grasslands under ambient climate, but was strongly reduced under future climatic conditions. The farmlands were less affected by climate. Overall, the intensively managed grassland showed the lowest feeding activity of all land-use types.
Surprisingly, the strongest climate effect was found for extensive grasslands, whereas the intensive grassland and farmlands were less affected - suggesting that less intensively managed systems are more vulnerable to climate change. This confirms our hypothesis that the magnitude of climate change effects on essential ecosystem functions like soil animal feeding activity is strongly contingent upon how ecosystems are managed.