Food web control of the global topsoil carbon cycling

ongoing

Soil food webs process 90% of the terrestrial primary production and regulate the second largest carbon pool on Earth – soil organic matter. Soil food webs themselves are regulated by soil animals through changes in microbial functioning, detritus quality, and physical soil structure. However, neither drivers of soil food web structure and functions nor their effects on global biogeochemistry and carbon stabilisation are quantified across large environmental gradients. CARBONWEB addresses this challenge at the global scale and tests the following Key Hypotheses: (A) biotic controls of soil food web structure and functions increase under conditions promoting biological activity and nutrient limitation; (B) consumption of detritus by consumers in soil food webs increases the stable fraction of soil carbon across ecosystem types; (C) the effect of soil animals on multiple ecosystem functions increases with temperature, precipitation, and nutrient limitation, proportionally to the total energy flux in soil food webs; (D) the global net effect of soil animals on topsoil carbon is positive (>10% increase) and will increase with climate warming. To test my hypotheses, I will use (1) the first comprehensive global monitoring of soil animal communities in the framework of Soil BON, (2) an EU-wide survey and isotopic experiments on carbon stabilisation, (3) steady-state and dynamic food web modelling and AI-based animal image analysis approaches, and (4) geospatial extrapolations. My experience in soil macroecology, functional ecology, large-scale project coordination, and the established collaborative network will help to ensure this project is successful. I will describe and mechanistically model the status and trends of energy fluxes, animal biodiversity, and carbon pools in global topsoils. Results of the project will provide the first-ever global estimation of soil food web effects on soil functioning and facilitate long-term monitoring of soil biodiversity.