The role of arbuscular mycorrhizal fungi in plant litter decomposition

• Applicant: Dr. Eva Leifheit
• Subject Area: Ecology and Biodiversity of Plants and Ecosystems
• Term: from 2017 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 336287045

In the context of climate change there is increasing interest in belowground processes that influence soil carbon (C) cycling and stabilization. One key component of soil C cycling is the decomposition of plant litter, which can be strongly influenced by the microbial community composition. Recently, the influence of arbuscular mycorrhizal fungi (AMF) on litter decomposition has received considerable attention, but findings are ambiguous and seem to depend on litter quality and the length of the observation period. Additionally, stabilization of C in microbial biomass or in the soil matrix have been neglected in the past. As plant litter represents the main source for natural soil carbon sequestration, even small changes in turnover time can have a globally significant impact. Therefore, our knowledge of the cycling and potential stabilization of soil carbon is crucial for understanding and predicting global warming.The aim of this research project is to clarify the ambiguous role of AMF in plant litter decomposition. First, I propose to unravel the mechanisms that are responsible for altered decomposition rates in the presence of AMF. This will be realized with a set of experiments in which I will measure root and mycelial exudates, changes in nutrient content and moisture in the soil and activity of microbial groups involved in decomposition. Second, I propose to test for the generality of AMF effects on litter decomposition. For this, I will measure litter decomposition across different litter types, AMF species and soil types. Third, I propose to test the external validity of the laboratory results with a field experiment. By using plant litter labelled with stable isotopes I will not only follow the loss of litter but also the fate and potential stabilization of C in the soil. This research project will contribute to our understanding of the ecology of the AMF symbiosis and our knowledge of belowground processes of soil C cycling.

• DFG Programme: Research Grants