Effects of temperature on soil organic carbon mineralization rate and enzyme kinetic para-meters in temperate and subtropical forests.

Abstract

We examined the effects of temperature on SOC mineralization rate (Cmin) and enzyme kinetic parameters in soils of two different latitudinal forests, i.e., broad-leaved Korean pine forest in Changbai Mountain at higher latitude and evergreen broad-leaved forest in Dinghu Mountain at lower latitude. The results showed that the soil Cmin increased with temperature, and the Cmin and Q10(Cmin) of the Changbai Mountain forest soil were higher than those of the Dinghu Mountain forest soil. The maximal rates of velocity (Vmax) and the half-saturation constant (Km) of the Changbai Mountain forest soil were higher relative to the Dinghu Mountain soil for both soil β-glucosidase (βG) and N-acetyl-β-D-glucosaminidase (NAG), but being opposite for catalytic efficiency (Vmax/Km). Both Vmax and Vmax/Km of βG and NAG increased with the increase of incubation temperature, while Km decreased, i.e., the affinity of enzymes to the substrate were increased. Inconsistent with the soil Q10 (Cmin), Q10(Vmax) and Q10(Km) of the soil βG were higher in Dinghu Mountain forest soil than those in the Changbai Mountain forest soil. The mechanisms underlying the effects of temperate variation on Cmin and the enzyme kinetic parameters were different, and thus the temperature sensitivity of Cmin and enzyme kinetic parameters should be considered differentially in the models of soil biochemical process.