Soil Warming, Carbon-Nitrogen Interactions, and Forest Carbon Budgets
Soil warming has the potential to alter both soil and plant processes that affect carbon (C) storage in forest ecosystems. DOE-supported scientists have quantified these effects in a large, long-term (7-year) soil-warming study in a deciduous forest in New England. Soil warming has resulted in C losses from the soil and stimulated C gains in the woody tissue of trees. The warming-enhanced decay of soil organic matter also released enough additional inorganic nitrogen (N) into the soil solution to support the observed increases in plant C storage. Although soil warming has resulted in a cumulative net loss of C, the annual net losses generally decreased over time as plant C storage increased. In the seventh year, warming-induced soil C losses were almost totally compensated for by plant C gains. The research team attributes plant gains primarily to warming-induced increases in N availability. This study underscores the importance of incorporating C–N interactions in atmosphere–ocean–land earth system models to accurately simulate land feedbacks to the climate system.
Melillo, J. M., S. Butler, J. Johnson, J. Mohan, P. Steudler, H. Lux, E. Burrows, F. Bowles, R. Smith, L. Scott, C. Vario, T. Hill, A. Burton, Y. M. Zhou, and J. Tang. 2011. “Soil Warming, Carbon-Nitrogen Interactions, and Forest Carbon Budgets,” Proceedings of the National Academy of Sciences 108, 9508–9512.