Evaluating the Impacts of Seasonal Root and Litter Quality and Biomass on Belowground Carbon Dynamics

Soil carbon is the largest terrestrial carbon sink in the biosphere. Heterotrophic soil respiration (Rh) is one terrestrial to atmospheric flux path for carbon, an important component in climate change. While the relationship of soil respiration with soil temperature and moisture is well studied, less is known about the impact of seasonally available soil organic matter (SOM). This project aims to better understand Rh, specifically its relationship with seasonal forest litter and root variation. Through biannual root and monthly litter biomass collections, as well as seasonal measurements of carbon and nitrogen ratios (CN), we will determine the impact root and litter quantity and quality has on Rh. We anticipate that root biomass die-off and litter accumulation during the fall will increase Rh. Further, we expect fall CN ratios to decrease, resulting in higher carbon use efficiency in microbial decomposers and increased Rh compared to the spring. This would suggest seasonal variations in SOM CN may amplify Rh flux patterns resulting from seasonal biomass differences. This project seeks to verify the impact of seasonal biomass on Rh , and determine if biomass alone is an effective tool for modelling soil respiration factors, or if seasonal CN differences must also be accounted for