Effects of stem and leaf decomposition in typical herbs on soil enzyme activity and microbial diversity in the south Ningxia loess hilly region of Northwest China

Abstract

With the method of litter bags, the characteristics of soil enzyme activities, soil microbial diversity at later stage of decomposition, and the relationships between soil enzyme activity and initial soil property were investigated in the process of stem and leaf decomposition of three typical herbs, i.e., Stipa bungeana, Artemisia sacrorum and Thymus mongolicus in the south Ningxia loess hilly region, Northwest China. The results showed that soil enzyme activity increased under different treatments after 480 d during stem and leaf decomposition. Soil sucrose activity (32.40 mg·g-1·24 h-1) and alkaline phosphatase activity (1.99 mg·g-1·24 h-1) were the highest in S. bungeana treatment. Soil urease activity (2.66 mg·g-1·24 h-1) was the highest in T. mongolicus treatment, and soil cellulase activity (1.42 mg·g-1·72 h-1) was the highest in A. sacrorum treatment. Soil cellulose activity at later stage of decomposition had significant positive correlation with initial microbial biomass carbon of soil. Soil cellulose activity at later stage of decomposition had significant negative correlation with initial nitrate nitrogen content of soil. Ace index, Chao index and Shannon index of soil bacteria and fungi in plant tissue addition treatments were higher than in the control. However, Simpson index was opposed. The stem and leaf decomposition significantly promoted the abundance and diversity of soil bacteria and fungi, accelerated the decomposition rate of stems and leaves, and promoted the cycle and transformation of soil nutrients.