Kinetic parameters and temperature sensitivity of soil nitrogen and phosphorus transforming enzymes in Robinia pseudoacacia plantations under different vegetation zones on the Loess Plateau, China

Abstract

Soil enzymes are catalysts for organic matter decomposition, the kinetic characteristics of which are important indicators of the catalytic performance of enzymes, with important role in evalua-ting soil health quality. We examined the responses of soil enzyme kinetic parameters to temperature change and the variation characteristics of their temperature sensitivity (Q10) in Robinia pseu-doacacia plantation soil under three different vegetation zones on the Loess Plateau. The results showed that the potential maximum reaction rate (Vmax) and the half-saturation constant (Km) of alanine transaminase (ALT), leucine aminopeptidase (LAP) and alkaline phosphatase (ALP) all increased linearly with the increasing incubation temperature. The zonal regularity of forest zone > forest-steppe zone > steppe zone was presented in Vmax. The temperature sensitivity of Vmax(Q10(Vmax)) ranged from 1.14 to 1.62, and the temperature sensitivity of Km(Q10(Km)) ranged from 1.05 to 1.47, with both values being lower in forest-steppe zone than other vegetation zones. In low and high temperature regions, the variations of Q10 in different soil enzymes differed among vegetation zones. Results from redundancy analysis showed that Q10 had a significant correlation with environmental variables, especially soil nutrients, indicating that Q10 would be affected by other environmental factors besides temperature.