温度对温带和亚热带森林土壤有机碳矿化速率及酶动力学参数的影响

研究了温度对长白山阔叶红松林、鼎湖山常绿阔叶林2个不同纬度的森林土壤有机碳矿化速率和酶动力学参数的影响.结果表明:土壤有机碳矿化速率(C_min)随着温度的增加而增加,长白山土壤C_min及其温度敏感性(Q_10(Cmin))显著高于鼎湖山土壤.长白山土壤β-1,4-葡萄糖苷酶(βG)和β-1,4-N-乙酰葡糖氨糖苷酶(NAG)的酶动力学参数潜在最大反应速率(V_max)和半饱和常数(K_m)高于鼎湖山土壤,但鼎湖山土壤的催化效率(V_max/K_m)高于长白山土壤,表明随着温度的升高,土壤βG和NAG的V_max和V_max/K_m增加,K_m降低,即酶与底物的结合程度增加.鼎湖山土壤βG的Q_10(Vmax)、Q_10(Km)高于长白山土壤,这与土壤Q_10(Cmin)结果不一致.增温对长白山和鼎湖山森林土壤有机碳矿化及酶动力学参数的影响机制不同,在土壤生物化学过程对增温响应的模型中应区别考虑.

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

We examined the effects of temperature on SOC mineralization rate (C_min) 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 C_min increased with temperature, and the C_min and Q10(C_min) of the Changbai Mountain forest soil were higher than those of the Dinghu Mountain forest soil. The maximal rates of velocity (V_max) and the half-saturation constant (K_m) 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 (V_max/K_m). Both V_max and V_max/K_m of βG and NAG increased with the increase of incubation temperature, while K_m decreased, i.e., the affinity of enzymes to the substrate were increased. Inconsistent with the soil Q10 (C_min), Q10(V_max) and Q_10(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 C_min and the enzyme kinetic parameters were different, and thus the temperature sensitivity of C_min and enzyme kinetic parameters should be considered differentially in the models of soil biochemical process.