The functional role of soil biodiversity in grassland habitats: effects of land use and climate on niche properties, decomposition and greenhouse gas fluxes

• Applicant: Professor Dr. Volkmar Wolters
• Subject Area: Ecology and Biodiversity of Plants and Ecosystems
• Term: from 2008 to 2016
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 61150987

Our previous studies carried out within the DFG Biodiversity Exploratories revealed a significant and very often non-linear response of soil fauna biodiversity and functioning in grasslands to land-use and climatic gradients. Now we need to understand the mechanisms driving these response patterns by asking whether modifications of soil biotic processes occur through changes in species composition of the community (species turnover) or through shifts within the existing community. The latter include both interspecific shifts (alterations of the dominance structure) and intraspecific shifts (changes in the expression of certain morphological, functional, behavioral or reproductive traits). The phenotypic plasticity of soil animals provides a particular challenging case, since trait shifts allow rapid and reversible changes of the species functional roles in response to changing environmental conditions. Considering that species turnover in soil is slow due to the low migratory potential of belowground biota, such intraspecific response mechanisms most probably are much more important than previously thought. Our key hypothesis is that individual species trait plasticity significantly contributes to the striking functional redundancy and resilience of soil animal communities under conditions of climate change and increasing land-use intensity. We further hypothesize that functional shifts of belowground food webs resulting from alterations in dominance and species composition can partly be compensated by trait-related functional expansion of the remaining species. Both compositional responses at the community level and trait responses at the species level will be quantified by continuing, extending and refining field studies as well as by experimental approaches in microcosms that have been successfully established in the two preceding projects (SoilFoodWeb, SoilFun). Concerning the extension of field studies, SoilTRAIT aims at collaborating with all projects addressing processes that are related to soil biodiversity in grasslands. Within this context, a particular focus will be on quantifying a wide range of functional traits of the soil fauna and their changes in response to varying environmental conditions. Community analyses based on soil samples will cover the broadest range of invertebrate taxa possible, but specific trait analyses will focus on representative groups of soil decomposers (millipedes, collembolans, oribatid mites, enchytraeids, and earthworms) and predators (gamasid mites, spiders, carabid beetles). Integrating these new insights into our food web approach to the functional role of soil animals in grasslands established in previous projects will not only increase the reliability of descriptive and predictive models on soil ecological processes, but it will also allow us to quantify the limits of soil community resilience and sustainability in the face of environmental change or of short-term stress.

• DFG Programme: Infrastructure Priority Programmes
• Subproject of: SPP 1374: Biodiversity Exploratories