Recent research suggests that even modest temperature increases could cause large releases of CO2 from the soil; a one-degree temperature increase could prompt soil carbon losses (as CO2) equivalent to five times the annual CO2 release from all fossil fuel burning. But, such forecasts are based on short-term data that implicitly assume all of the carbon in the soil is uniformly temperature sensitive. The bulk of applicable research suggests that older, more resistant carbon fractions may be less temperature sensitive. We hypothesize that the physical, chemical, and biochemical mechanisms that protect soil carbon from decomposition act to reduce the temperature sensitivity of soil carbon. An important corollary is that soil carbon stocks are less vulnerable to changes in temperature than previously supposed. We will test this hypothesis by comparing temperature sensitivities of soils with more labile material versus soils with less.

Results from this work will reduce uncertainty about the vulnerability of soil carbon stocks to changes in temperature, thus improving information available to aid decision makers. This research will also advance our understanding of basic ecosystem dynamics, present a number of unique opportunities for undergraduate and graduate training, and build international collaboration.

This conceptual diagram illustrates our hypothesized relationship between temperature sensitivity and SOM decomposability. We hypothesize that resistance to decomposition (physical, chemical, and bioc

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