Temperature sensitivity of soil respiration: Uncertainties of global warming positive or negative feedback

Abstract

Several models indicate that a positive feedback of an increasing atmosphere CO2 concentration to global warming would occur, which will accelerate the global warming in the current century. However, these models' results largely rely on an important hypothesis: Decompositions of soil organic matter with different mean resident time have the same temperature sensitivity (Q10). This hypothesis, however, is contrary to enzyme kinetic theory. Furthermore, a consensus has not yet reached on whether the temperature sensitivity of soil organic matter decomposition positively, negatively or do not change with different soil organic matter quality. Therefore, the significance of the positive feedback of global warming and the increasing atmosphere CO2 concentration is still to be explored before this divergence comes to an agreement. In this paper, a review was made on the following issues: 1) controversy issues on the temperature sensitivity of soil organic matter decomposition, 2) disagreement on Q10 estimation based on experiential model curve fitting and the mechanism of Q10 variation, 3) issues resulting from soil incubation experiments, 4) a modified method to calculate Q10 through soil incubation experiments. Deepening understanding of the uncertainties of temperature sensitivity of soil organic matter decomposition is of significance to future research on soil organic matter decomposition and soil respiration response to global warming.