Biodiversity Exploratories - Effects of landscape context and land-use intensity on biodiversity and multitrophic interactions among plants, pollinators, herbivores, and their natural enemies

DFG - STE 957/7-1

Responses of biodiversity to components of global change, such as land use intensification, are relatively well documented. However, related changes of food-web structures, community dynamics, and trophic interactions are little known yet vital aspects of ecosystem functioning. In three biodiversity exploratories we will perform standardised and highly replicated experiments across land use intensity gradients in both forest and grassland habitats (300 intensively studied plots). Landscape composition will be quantified within a radius of 2 km around the study plots, which will allow analyses of the combined effects of local use intensity and regional landscape context on the studied biotic interactions. A trap nest experiment will be established to study patterns of species richness, population dynamics, und biotic interactions of bees, wasps and their natural enemies. The trap nest experiment will provide data to quantify shifts in food web characteristics and community structures. In addition, host-parasite interactions will be analysed using bumblebees and their colonies as model systems. In standardised experiments with naturally occurring and experimentally exposed phytometer plant species, pollination limitation, seed predation, herbivory, and parasitism will be studied in two different resource environments. We adopt a paired approach by comparing fenced and unfenced forest plots, and mown and unmown grassland plots, respectively. In conclusion, the proposed experiments will provide complementary data with synergistic value for the overall project on the relationship between non-random species loss and key ecosystem functions.