Land use and biodiversity determine the contribution of microbial necromass to soil carbon storage (BioNeCS)

• Applicants: Dr. Qing-Fang Bi; Professor Dr. Bruno Glaser; Dr. Kezia Goldmann; Dr. Klaus Kaiser; Luis Daniel Prada-Salcedo, Ph.D.; Dr. Marion Schrumpf
• Subject Area: Soil Sciences ; Ecology of Land Use
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 512408200

Microbial carbon assimilation and subsequent necromass build-up is expected to contribute greatly to soil organic carbon, though more in grasslands than in forests. The factors regulating the formation, accumulation, and stabilization of microbial necromass in soil are so far not well understood. We aim at exploring how land use and biodiversity drive extent and underlying mechanisms of necromass-induced formation of stable soil organic matter. The setup of the Biodiversity Exploratories offers the unique opportunity to study the response of soil necromass build-up along land use intensity gradients on different soil types. We hypothesize that land use and associated changes in plant and microbial communities modify the formation and fate of microbial necromass in soils. We expect that type and intensity of land use and biodiversity affect (1) the functional adaption of the microbial community to different substrates and, consequently, their carbon use efficiency, (2) the microbial community composition, such as the share of fungi and bacteria and of k- and r-life strategists, (3) the relation between decomposition and stabilization of necromass by interactions with minerals, and therefore (4) ultimately the overall contribution of microbial necromass as well as the individual contribution of bacteria and fungi necromass to soil organic matter. In order to address possible effects of necromass formation and stabilization separately, we will study on the one hand the active microbial biomass, its physiological properties (growth and carbon use efficiency), community composition and functional properties, and on the other hand the fate of bacterial and fungal necromass in soils. Stabilization of root-derived carbon via recycling in the microbial biomass will also be addressed, by tracing labelled root litter in respective microbial biomarker (amino sugar). The latter will be used to determine finally the contribution of fungal and bacterial necromass to topsoil and subsoil organic matter of the Biodiversity Exploratories. We expect that our comprehensive and complementing approach will significantly improve our understanding on the role of microbial necromass to soil carbon sequestration.

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