The driving role of the microbial carbon balance in ecosystem responses to climate change – BALANCE

Soil microorganisms globally are thought to be a source of carbon (C) because of their central role in releasing greenhouse gases (carbon dioxide and methane). Certain bacteria, archaea and protists consume inorganic C such as carbon dioxide, carbon monoxide and methane, but they are presumed either to be rare community members or with insignificant C assimilation capacities compared to plants. Yet emerging evidence shows that microbial C uptake can contribute significantly to terrestrial primary productivity. Given that both microbial C uptake and release coexist in soils, an enduring question is to which extent and under which conditions these microbial C processes counterbalance each other. Particularly, any decoupling among these coexisting microbial processes resulting from climate change is likely to have consequences for the whole-soil C balance, with unforeseen consequences for future climate conditions. BALANCE will use integrative microbiome studies to advance our fundamental knowledge of how microbial physiological responses to climate change modulate soil-atmosphere C exchanges in peatland ecosystems— a major soil C pool. Specifically, this project aims to 1) probe the metabolic rates that underpin microbial C balance. 2) Examine the biotic and environmental controls of the microbial C balance across space and time to extrapolate its control over peatland C dynamics at the global peatland scale. 3) Perform observational and experimental studies to reveal how climate change alters microbial C balance and predict the consequences at the global peatland scale using geospatial modelling. To fulfil these aims, this work will utilize a powerful approach that harnesses metagenomic, biogeochemistry and geospatial modelling. Its achievement will mark a step-change in microbial ecology theory and understanding, and address a critical research challenge of the Anthropocene in a key natural ecosystem: how climate change will impact soil C cycling by the soil microbiome.