How Does Warming Alter Soil Organic Matter Under Elevated CO2?.

How does warming alter soil organic matter under elevated CO2? Amanda Brennan, Elise Pendall, Yolima Carrillo and Jack Morgan Understanding plant and soil community response to climate change is a vital component of predicting future ecosystem response and carbon sequestration. As global climate patterns shift, ecosystem structure and function are expected to change. The Prairie Heating and CO2 Enrichment (PHACE) experiment provides an excellent framework for identifying biological and environmental drivers associated with global change. The elevated CO2 treatment uses a 13C depleted source which allows tracing soil carbon inputs and outputs. Stable isotope techniques are an effective tool in determining changes in soil organic matter in various climatic conditions. At PHACE, persistent carbon loss due to increased ecosystem respiration has been observed. A critical element in understanding the significance of increased soil respiration is the partitioning between the autotrophic and heterotrophic origin of the respired carbon. Warming is thought to stimulate decomposition and ecosystem carbon loss; however, this grassland ecosystem is water limited and warming may suppress decomposition due to increased drying. This research is aimed at understanding how soil carbon is affected by changes in atmospheric CO2 and temperature. In particular I will use stable isotopes to trace new carbon inputs to soil pools and quantify if warming under elevated CO2 leads to a loss of recalcitrant carbon. This data will provide insight into the potential carbon sequestration or loss in a predicted future climate.