Responses of grassland vegetation and soil nutrients to desertification in Qilian Mountains of eastern Qinghai-Tibetan Plateau

Abstract

To explore the change characteristics of vegetation and soil nutrients in grassland desertification, the study intends to using the method of replacing space with time, taking temperate steppe (TS), temperate steppe desert (TSD) and temperate desert (TD) in Qilian mountains as the research objects, and analyze the change characteristics of vegetation and soil nutrients replacing succession of grassland desertification. The study indicated that, from TS, TSD to TD, the total coverage, AGB, Shannon-Weiner index and richness, total porosity, total N, soil organic matter, C/N, C/P, N/P, alkaline phosphatase, catalase, sucrase were decreased, and grass layer height, dominance, soil bulk density and pH were increased. While the total P, total K and available P were first increased and then decreased, and were opposite to evenness and urease enzyme activity change. Meanwhile, the C/N, C/P and N/P of three grassland types ranged from 5.06-17.27, 2.49-71.94 and 0.50-4.19. Correlation analysis showed that, except for available P, available K, and evenness, there was a significant correlation between other vegetation and soil indicators. In conclusion, in the process of grassland desertification, grassland vegetation and soil had undergone significant changes, especially total coverage, AGB, Shannon-Weiner index, soil bulk density, soil organic matter and total nitrogen. Based on N/P, the nitrogen was the main factor limiting the productivity of grassland, and the limitation was more prominent in the process of grassland desertification.