Effect of livestock exclusion duration years on plant and soil properties in a Tibetan alpine meadow

Livestock exclosure is widely used to restore alpine grasslands, though there is still dispute regarding the optimal duration. In the present study, we investigated how exclosure duration affected plant species biodiversity, vegetation biomass, and soil properties in an alpine meadow, by surveying grazing exclosure in sites exclosed for 5, 7, and 11 years in the central Tibetan Plateau. Our results showed that all exclosure treatments consistently and significantly enhanced the species richness, biodiversity, vegetation coverage ratio, and aboveground biomass of the plant community. Among these treatments, the highest species richness and biodiversity were observed in the 7-year exclosure treatment, and a significant difference was found between the that in the 5-year and 11-year treatments. With respect to soil properties, all livestock exclosure treatments consistently reduced soil bulk density and enhanced soil organic content as compared with those of the grazing treatment. Livestock exclosure treatments also significantly enhanced soil total nitrogen and phosphorus content, though there was no difference between the treatments. In general, our study suggests that livestock exclosure could be effective for plant and soil restoration in alpine meadows, and 5-year and 7-year exclosure are better choices from an ecological perspective.