Effects of rest grazing on vegetation and soil characteristics of alpine steppe and alpine meadow in Tibet

Rest grazing is one of the primary grazing management and grassland protection strategies in Tibet to restore the vegetation and soil in degraded grasslands and maintain high diversity and biomass through natural regeneration. Considering the alpine steppe and alpine meadow in central Tibet as the research object, the effects of free grazing and rest grazing on plant species diversity, total biomass, balance between aboveground and underground biomass, and physical and chemical properties of alpine steppe and alpine meadow soils were studied through field investigation and laboratory experiment analysis. The results showed that rest grazing reduced Simpson, Pielou, and Shannon-Wiener indices of the plant community and increased the total biomass of vegetation in both alpine steppe and alpine meadow; however, the variations did not achieve any statistical significance. Furthermore, rest grazing increased the balance value of aboveground and underground biomass, thereby contributing to the growth and development of aboveground vegetation. The effect was more obvious in alpine meadow. In addition, no significant difference was observed in the effects of rest grazing and free grazing on soil mechanical composition, soil microaggregates, and soil nutrients in the alpine grasslands. Therefore, rest grazing exerted no obvious effects on vegetation restoration in the alpine grassland of Tibet, and no significant differences were observed between rest grazing and free grazing grasslands in terms of biodiversity of the community, vegetation biomass, and soil physical and chemical properties. As a consequence, the effect of rest grazing remains to be evaluated and studied in the future.