Understanding future arctic terrestrial carbon balance is vital because high latitude soils contain about twice as much carbon as is in the atmosphere and its release would drive a major acceleration of atmospheric carbon dioxide accumulation. This research will advance the understanding of processes regulating the storage and release of carbon from arctic soils across biological and physical scales using a modeling approach. The study will promote both basic research into the controls on arctic soil and ecosystem processes and be applicable to management agencies by describing how linked biotic-abiotic responses to unprecedented warming may influence future carbon balance in Arctic terrestrial ecosystems. Further, this grant will help advance the career of an Assistant Professor at a primarily undergraduate institution, while enhancing gender and racial diversity in the biogeosciences. This research will also directly enhance undergraduate education in arctic biogeoscience through directed mentorship of undergraduate researchers; the research approach and findings will also be incorporated into courses and other teaching activities by the primary investigators.<br/><br/>Field studies suggest that inconsistent responses to comparable experimental manipulations across arctic tundra ecosystems might be driven by local variation in the plant and decomposer community. However, the relative importance of, and links between, key biotic (e.g. microbial acclimation) and abiotic factors (e.g. altered snowpack, thaw depth, and nutrient availability) that govern these divergent responses of tundra to climate variation, remains unknown. This project will synthesize available data from ambient and experimental manipulations of arctic ecosystems. The investigators will then use the synthesis to refine, parameterize, and validate a changed version of the Stoichiometrically Coupled, Acclimating Microbe-Plant-Soil (SCAMPS) model. Simulations will explore how variation in seasonal warming and the acclimation potential of the soil microbial and plant community, encompassing community shifts, evolutionary adaptation, and physiological changes across tundra landscapes, affects biogeochemical feedbacks and regulates future carbon balance of arctic soils and ecosystems.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.