Soil Warming and Carbon-Cycle Feedbacks to the Climate System

In a decade-long soil warming experiment in a mid-latitude forest in central Massachusetts, we have measured the responses of soil carbon and nitrogen dynamics to a year-round soil temperature increase of 5°C. We have found that while soil warming accelerates soil organic matter decay and, in the short term, CO₂ flux to the atmosphere, it also increases the availability of mineral N to plants. This increase in nitrogen availability creates conditions needed for increases in carbon storage in these ecosystems where tree growth is nitrogen limited. For many mid-latitude forests, warming may actually stimulate carbon storage at the ecosystem level and thus slow the rate of climate change.