9623433 Harte Global warming and soil organic matter dynamics: an experimental investigation of the effects of climate on soil carbon pool structure. Results from an ongoing warming manipulation in a high-altitude meadow ecosystem indicate that warming may be reducing the stock of carbon in the bulk soil organic matter. Since such an effect would constitute a positive feedback mechanism to the global warming predicted to follow from current greenhouse gas emissions, understanding it is important to fully understanding global warming itself The funds requested by this proposal will provide for a further investigation of the structure of the soil carbon pool in the study ecosystem. The aim is to better quantify the magnitude of the soil carbon loss, identify the pools of soil carbon from which it comes, and understand the underlying dynamics that will determine the timescale over which it might operate. Specifically, the PIs propose to apply: 1) recent advances in soil organic matter fractionation techniques, and 2) new methods being developed to quantify the structure of microbial decomposer communities, to soils from the warming manipulation. Organic matter fractionation divides soil carbon into pools according to turnover time (thereby revealing structure essential to predicting the long-term response to warming); identifying any potential shifts in the microbial decomposer community that might be associated with changes in the soil carbon structure will help illuminate biological mechanisms important in ecosystem response to warming.
