Integrative molecular biogeochemistry of long-term litter quality and quantity controls on soil organic matter composition and persistence in temperate forests

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Globally, soils store twice as much carbon as the atmosphere. The cycling of soil carbon is an intricate balance between carbon inputs, from plants and microbes, and removals, from microbial respiration (CO2 flux) and soluble carbon export or translocation through the soil profile. The world's forests store ~45% of terrestrial carbon stocks and contribute to ~50% of the net primary productivity. Recent studies have demonstrated that these forests and their vast carbon reserves are under threat due to anthropogenic climate change which is destabilizing soil carbon and making it susceptible to microbial degradation and export from soil profiles. As such, forest soil carbon is declining globally and this will negatively impact the health of forests and the important ecological services that they provide. It is hypothesized that a major proportion of soil carbon is derived from plant inputs and deposition to soil. Therefore, changes in vegetation type and quantity will also alter soil carbon storage processes. The proposed research program will use an integrative molecular biogeochemistry characterization platform to study the long-term impacts on forest soil carbon with changes in litter deposition and litter quality. As part of an international network of researchers, the applicant and her trainees, will study how long-term litter manipulations govern the quantity and quality of litter deposited to soil and how this subsequently alters soil carbon turnover and biogeochemistry. This program will study five different temperate forests that have undergone 15, 20, and 30 years of litter manipulation. This research program will be the first to study the molecular-level compositional changes of soil organic matter with long-term variation in litter inputs and how this alters soil carbon storage in forests. This research program will provide new knowledge on how soil organic matter and soil carbon are controlled by litter input changes through time and also how these differences are governed by soil and other ecosystem properties. This research program will also measure how changes in soil organic matter alter its ability to be exported or degraded through the solubilization of soil-derived carbon. This molecular-level data is critically needed to develop better management strategies for forests and ensure their long-term sustainability in a changing world. Current environmental policies require more accurate scientific knowledge regarding the sensitivity of soil carbon to potential shifts in litter inputs. Consequently, this proposed research will provide new information that will help shape future environmental mitigation strategies for protecting soil carbon in temperate forests and other sensitive ecosystems around the world.