Soil food-web control of the carbon cycle in forests across climates and mycorrhiza types

• Applicant: Professor Dr. Anton Potapov
• Subject Area: Soil Sciences ; Ecology and Biodiversity of Animals and Ecosystems, Organismic Interactions
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 493345801

The carbon cycle supports the life of Earth. Soil is the largest pool of terrestrial carbon and it is also the largest pool of terrestrial biodiversity. Despite that, most of the current models of carbon cycling are based on climate and vegetation, not taking in account complex biological communities in soil, comprising microorganisms, protists and a wide range of invertebrates. It is increasingly recognized that soil biodiversity actively alters carbon cycling, which is evident from different carbon stocks in ecosystems dominated by trees associated with ectomycorrhizal (EMF) or arbuscular mycorrhizal (AMF) fungal symbionts in soil. In this project, my intention is to go a critical step further and quantify the role of the entire soil communities in the carbon cycle in forest ecosystems. While microbial functions are relatively well described, soil animals may exhibit complex indirect effects on the processes of organic matter transformation in soil. In particular, there are two main mechanisms how soil animals affect ecosystem functioning – selective grazing on certain functional groups of microorganisms, and shredding, transformation and vertical translocation of organic matter. My hypothesis is that these two mechanisms result in different effects on the carbon cycle in EMF- and AMF-dominated forest ecosystems. Until today, there is no systematic comparison of the composition and trophic organization of soil communities in EMF- and AMF-dominated forest ecosystems. I developed a novel soil food web reconstruction approach which includes multiple aspects of trophic interactions in soil and can be used to assess the ‘trophic multifunctionality’ in ecosystems. Using this integrative approach in the proposed project I will compare EMF- and AMF-dominated forest ecosystems by combining (1) field experiments with novel isotope methods in old-growth temperate forests, (2) meta-analysis of data from experimental platforms and natural forests across temperate, subtropical and tropical ecosystems, and (3) a controlled Ecotron-based experiment, testing the context-dependent effect of soil food webs on ecosystem functioning. The anticipated results of the project will allow to analyse the role of soil animals in carbon cycling in EMF and AMF forest ecosystems. The project will deliver a comprehensive set of functional indicators of soil food webs that can be used to communicate scientific knowledge to authorities, and to link soil biodiversity with ecosystem functioning in forest soils, from the local to the global scale.

• DFG Programme: Independent Junior Research Groups