Collaborative Research: Permafrost climate feedbacks: How interactions among plants, microbes, and minerals affect biogeochemical projections in a changing Arctic

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The Arctic is warming at a rate faster than elsewhere on Earth, resulting in changes to Arctic ecosystems that may affect global climate. Permafrost is ground that remains frozen for at least two consecutive years. It occurs under approximately one fourth of the northern hemisphere's land surface and contain as much carbon as the entire atmosphere. Permafrost thaw leads to changes in the dominant vegetation and makes the carbon stored in the permafrost soil vulnerable to decomposition, but existing measurements and models disagree about the implications of these changes for the global carbon cycle. This research project investigates how processes mediated by microbes, minerals, and their interactions with vegetation affect the vulnerability of carbon in permafrost soils. The researchers are carrying out laboratory and growth chamber studies to investigate microbial communities and the transformations of carbon with permafrost thaw. They are incorporating the results of those studies into Earth system models to understand feedbacks to the climate system. This research is addressing critical knowledge gaps about how carbon stored in frozen permafrost will affect the Earth's carbon cycle, which is information urgently needed to inform climate change adaptation and mitigation strategies.This project is addressing the question: how will feedbacks between plants and soils (specifically minerals and microbes) affect arctic soil carbon balance in response to global change? Using state-of-the-science tools, such as microbial sequencing and stable isotope tracing, the researchers are carrying out (1) laboratory incubations to determine how soil microbial communities and mineralogy affect the fate of plant exudates and the vulnerability of native soil organic matter in thawed permafrost, and (2) plant-soil growth chamber mesocosms to trace belowground plant deposits into permafrost soils under ambient and elevated CO2. These findings are being used to develop and evaluate a microbial-enabled model that can handle the complexity of plant-microbe-mineral feedbacks. This soil model is being integrated into the Community Land Model (CLM) to predict the impact of permafrost thaw on the arctic carbon budget. This research enables better long-term projections of permafrost-climate feedbacks. The project is training the next generation of interdisciplinary Arctic scholars well-versed in scales ranging from microbial genes to global elemental cycles through PhD assistantships, postdoctoral research, and undergraduate laboratory education. In addition, the project provides training for up to 50 early career researchers on the theory and practice of land modeling, with a special focus on Arctic systems.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.