Increasing grazing intensity enhances vegetation elemental coupling but reduces soil elemental coupling in alpine meadows

Background Grazing alters the biogeochemical cycles in grassland ecosystems, with the elemental coupling serving as an effective measure of this impact. The concept of elemental coupling allows for the inclusion of various mineral elements, offering new insights into the effects of grazing on the material cycling. Methods This study focused on a typical alpine meadow in the eastern Qinghai-Tibet Plateau, where we measured the total elemental content of dominant vegetation, soil exchangeable ions, and soil physicochemical properties. We analysed the changes in soil and plant elemental coupling and used a Structural Equation Modeling (SEM) approach to investigate the mechanisms driving these changes. Results With increasing grazing intensity, the concentrations of heavy metals such as copper (Cu²⁺), zinc (Zn²⁺), manganese (Mn²⁺), and iron (Fe³⁺) significantly increased in the soil, while the contents of essential nutrients such as Mg, Ca, and Na decreased in the vegetation. Increasing grazing intensity enhanced vegetation element coupling but reduced soil element coupling, with increases of 52.8% and decreases of 16.8% under heavy grazing, respectively. SEM analysis revealed significant direct effects of grazing intensity on the changes in coupling. Conclusion This study investigated how grazing affects elemental coupling in an alpine meadow on the eastern Qinghai-Tibet Plateau. While grazing intensity enhances vegetation element coupling, it reduces soil element coupling.This study provides new perspectives and scientific basis for rational grazing management and sustainable grassland use.