Publication issue des travaux du projet CARBOSOIL

Synthesis analysis of the temperature sensitivity of soil respiration from laboratory studies in relation to incubation methods and soil conditions

The temperature sensitivity of soil respiration is a main factor determining the response of global terrestrial soil carbon to global warming and, consequently, its feedback on atmospheric CO2 concentrations. A data synthesis was performed to summarize information available in the literature on the temperature sensitivity of soil respiration obtained in laboratory soil incubations and expressed as Q10. The influence of common experimental variables and methods, i.e. range of incubation temperatures, length of incubation, calculation methods, and amounts of soil organic carbon, was analyzed.
We found a small but significant difference between the Q10 values calculated with different experimental methods as well as time-related trends showing an initial decrease followed by stable values. Q10 values ranged from 0.5 to over 300 and were negatively correlated with temperature, but only at the range of temperatures below 25
C. A similar dependence of the activation energy (derived from the Arrhenius equation) with temperature was observed. A negative relationship with total organic carbon content of soils was found in forest and grassland ecosystems, with an average decrease in Q10 of 0.02 mgC g1 soil, explaining their slightly lower mean Q10s compared to cultivated soils. Because most of the observed variability remained unexplained, we emphasize the need for new approaches in future studies to the problem of understanding the temperature sensitivity of soil organic matter decomposition.