Soil Enzyme Activity in Picea schrenkiana and Its Relationship with Environmental Factors in the Tianshan Mountains, Xinjiang

Abstract

Nitrogen deposition may affect forest soil traits and metabolic activity. We would like to further understand the mechanisms of soil biochemical processes and habitat interactions under conditions of nitrogen deposition in forests and to investigate the characteristics of soil enzyme activities and soil environmental factors in response to nitrogen deposition in Picea schrenkiana forests in the Tianshan Mountains. In this study, nitrogen application tests were carried out using the nitrogen sedimentation gradient method on Picea schrenkiana forest soils in the Tianshan Mountains. We analyzed the characteristics of soil enzyme activity and soil environmental factors at different nitrogen application levels and discussed the correlation between soil enzyme activity and soil environmental factors in conjunction with a redundancy analysis. The study showed that:① Soil enzyme activities showed a tendency to increase and then decrease with the increase in nitrogen application. With the exception of soil acid phosphatase, all enzyme levels reached maximums in the low nitrogen treatment. ② Exogenous nitrogen addition led to low soil pH values, and in the low or medium nitrogen treatments, soil conductivity and the content of organic carbon, ammonium nitrogen, ammonium nitrogen, and total phosphorus increases, along with the C/N ratio, while the N/P ratio showed an irregular decline. ③ Soil enzymes and their correlation with soil environmental factors showed that soil water content, organic carbon content, ammonium nitrogen content, total phosphorus content, and the C/N ratio were all significantly correlated with soil enzymes activity. Only the C/N ratio was negatively correlated with soil enzyme activity, while all other environmental factors were positively correlated with soil enzyme activity. There was no significant correlation between pH and the N/P ratio and soil enzyme activity. The important factors influencing soil enzyme activity were soil organic carbon and ammonium nitrogen with nitrogen application in Picea schrenkiana, Xinjiang.