A Meta-Analysis of The Effects of Grazing On Plant Diversity, Biomass and Soil Properties of Alpine Grassland On The Tibetan Plateau

Abstract

Aim As one of the main human disturbance factors in the alpine grassland on the Tibetan Plateau, grazing not only directly affects grassland plant diversity and biomass, but also indirectly changes soil carbon (C) and nitrogen (N) of grassland. Despite of extensive field grazing experiments, the impacts of grazing on grassland diversity, soil C and N remain uncertain due to different grazing management.Methods We conducted a meta-analysis of 70 peer-reviewed publications to evaluate the general response of 11 variables related to alpine grassland plant-soil ecosystems to grazing.Results The results showed that grazing significantly increased species richness, Shannon-Wiener index and Pielou evenness index by 9.8%, 7.3% and 3.7%, respectively. Aboveground biomass, belowground biomass, soil organic carbon, soil total nitrogen, soil C: N ratio and soil moisture decreased by 41.9%, 17.7%, 13.1%, 12.6%, 3.3% and 20.8%, respectively. Soil bulk density and soil pH increased by 17.5% and 2.2%, respectively. Specifically, moderate grazing, long-duration (>5 years) and winter grazing contributed to the increase in the species richness, Shannon-Wiener index, and Pielou evenness index. Aboveground biomass, belowground biomass, soil organic carbon, soil total nitrogen and soil C: N ratio showed a decreasing trend with enhanced grazing intensity. Furthermore, grazing duration, grazing season, livestock type and grassland type also affected alpine grassland plant diversity, biomass, soil C and N.Conclusions Grazing is beneficial to the maintenance of plant diversity, but negatively affects the storage of soil C and N in alpine grassland on the Tibetan Plateau. We suggest that grazing should follow intermediate grazing practice and synthesize other appropriate grazing patterns, such as seasonal and rotation grazing, thus, further research on grazing management is needed in this regard.

Effects of Long-Term Exclosure on Main Plant Functional Groups and Their Biochemical Properties in a Patchily Degraded Alpine Meadow in the Source Zone of the Yellow River, West China

“…Numerous studies have substantiated these findings. For instance, in a series of exclosure experiments conducted over 6, 11, and 12 years on the alpine grassland of the Qinghai-Tibet Plateau, Li et al [30] observed that exclosure significantly reduced the Shannon-Wiener diversity index and Margalef richness index of vegetation. Similarly, research conducted in Arizona, southwestern United States, demonstrated that grazing exclusion resulted in a decrease in native species and reduced the overall species richness compared to moderate grazing [31].…”