干旱区生态环境知识资源中心

Overgrazing has caused extensively vegetation destruction in deserts, the widely distributed type of grassland in northern Xinjiang, China. To restore the degraded desert ecosystems, grazing exclusion (GE) was extensively implemented in recent decades. However, changes in the vegetation characteristics and plant biodiversity in different years of GE have not been thoroughly elucidated. This study paper examines the changes in desert community characteristics (i.e., biomass, coverage, density) and plant biodiversity (i.e. Margelef richness index, Simpson dominance index and Pielou evenness index) under lightly degraded desert (LD) in Urumqi with freely grazing (FG), 1 a, 6 a,9 a and moderately degraded desert (MD) in Shawan with FG, 1 a, 4 a, 11 a. The results indicated that the vegetation density and biomass in LD had no statistical difference response to GE, while compared with FG, the coverage and biomass of GE sites in MD sigiiificantly increased by 36.9%-115.7% and 62.9%-217.5%, respectively. Relative short-term GE could increase Simpson dominance index and Margelef richness index in LD, but the Simpson dominance index and Pielou evenness index reduced in relative long-term GE condition. In addition, we suggests that the optimal vegetation biomass and plants growth condition of LD and MD were calculated and observed at the 4-5 a and 7-11 a in our study areas, respectively. Hence, we proposed that degraded deserts should adopt the grazing management when it recovered to a certain extent.