2-P4: Trophic Networks II

Carbon and energy flow in the soil microbiome – functional groups, activity and interactions in trophic networks

Soil organisms form highly complex trophic networks that regulate carbon turnover and energy dissipation in terrestrial ecosystems. However, it remains unclear how interactions between microorganisms and higher trophic levels structure the carbon and energy flow in soil. To address this, our project investigates the role of trophic interactions in regulating carbon allocation and energy dynamics during decomposition. A particular focus is given on major microbial grazers, the nematodes, and their effects on microbial activity and resource utilization as well as the bacterial and fungal channels of the micro-food web. We hypothesize that the trophic network structure is a key driver of carbon and energy use efficiency in soil, and that changes in grazer composition and multitrophic interactions lead to systematic shifts in decomposition pathways. The project uses controlled soil microcosms and ¹³C labelled substrates for budgeting C pools and fluxes. Combined with stable isotope probing (SIP) and metagenomic and -transcriptomic analyses this allows to track carbon flow into microbial communities and across trophic levels of the micro-food web. The resolved functional traits and metabolic pathways are linked to carbon and energy fluxes using thermodynamic measurements. The major goals of the project are:

(1) Determine the effects of bacterial grazers on the carbon and energy flow in the microbiome and how these dynamics are modulated by their interactions and functional traits

(2) Assign how complexity in functional groups of grazers alter microbial activity and pathways in metabolic transformation of resources, and

(3) Disentangle how altered microbial turnover processes, caused by differences in energy content and metabolic utilisation of substrates, affects the structural and functional organisation of higher trophic levels.

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Link to English scientific abstract
Link to German scientific abstract

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Research Team

Humboldt-Universität zu Berlin
Institute of Biology
Ecology Group