Temperature dependence of organic matter decomposition: a critical review using literature data analyzed with different models

The literature was reviewed regarding laboratory incubation studies where C mineralization was measured. Experiments were select-ed in which the same substrate was incubated at least at two different temperatures and where time-series were available with at least four measurements for each substrate and temperature. A first-order one-component model and a parallel first-order two-component model were fitted to the CO2-C evolution data in each experiment using a least-squares procedure. After normalising for a reference temperature, the temperature coefficient (Q(10)) function and three other temperature response functions were fitted to the estimated rate constants. The two-component model could describe the dynamics of the 25 experiments much more adequately than the one-component model (higher R-2, adjusted for the number of parameters), even when the rate constants for both were assumed to be equally affected by temperature. The goodness-of-fit did not differ between the temperature response models, but was affected by the choice of the reference temperature. For the whole data set, a Q(10) of 2 was found to be adequate for describing the temperature dependence of decomposition in the intermediate temperature range (about 5-35 degrees C). However, for individual experiments, Q(10) values deviated greatly from 2. At least at temperatures below 5 degrees C, functions not based on Q(10) are probably more adequate. However, due to the paucity of data from low-temperature incubations, this conclusion is only tentative, and more experimental work is called for.