Livestock exclusion enhances shrub encroachment in an alpine meadow on the eastern Qinghai‐Tibetan Plateau

Abstract

AbstractThe Qinghai‐Tibetan Plateau alpine grassland is experiencing shrub encroachment, which threatens the livelihoods of local nomads. Livestock exclusion management policies have also been implemented in this grassland. It has been predicted that shrubs here will likely encroach after long‐term yak elimination, but this inference is not supported by a manipulation experiment. To determine how shrubs respond to livestock grazing cessation, we investigated Potentilla fruticose L. characteristics and properties of herbs and soil in a ‘livestock exclusion‐free grazing’ system with exclosure experiments of 9, 17, and 23 years in the northeast region of the Plateau. We showed that each characteristic of shrub growth and reproduction was significantly greater in exclosures than in control plots, and shrub properties enhancements by livestock exclusion increased over time. We further found that this livestock exclusion induced‐shrub encroachment was related not only to the exclusion of livestock's direct disturbances but also to the competitive advantage gain of shrubs through plant–plant interactions and improvement of resources in deep soil for shrubs. Given the negative influences of shrub encroachment, especially lowering rangeland quality, livestock exclusion management in alpine grasslands should be used with caution.