Reconciling differences in predictions of temperature response of soil organic matter

Global warming has long been assumed to lead to an increase in soil respiration and, hence, decreasing soil carbon stores. This assumption has been based on short-term studies of litter and soil organic matter incubations. However, some recent studies seem to indicate that soil organic matter is less temperature sensitive than previously thought. We will in this paper use the continuous-quality theory to show that the temperature dependence of decomposition of soil organic matter depends on whether one studies soils at their native temperatures or soils that have been perturbed from their native temperatures. Turnover times of soil organic matter are more sensitive to temperature changes when they are estimated from typical incubation experiments with different temperatures than when they are estimated from soils at their native temperatures because the variation in turnover rate with native soil temperature is not the same as the temperature response of turnover rate of a given soil. This reconciles some seemingly incompatible results in the literature. (C) 2002 Elsevier Science Ltd. All rights reserved.