关键词: 硅添加, 群落稳定性, 磷添加

Abstract: Aims The alpine meadow ecosystem of the Qinghai-Tibet Plateau is highly sensitive to global change and human activities, with soil nutrient availability serving as a key factor regulating the structure and function of plant communities. Phosphorus (P), an essential element for plant growth, and silicon (Si), although non-essential, has the potential to enhance plant stress resistance and regulate nutrient absorption. However, their individual and interactive effects on the stability of alpine meadow communities remain unclear. Methods This study systematically investigated the effects of phosphorus, silicon, and their interaction on the structure, diversity, and stability of alpine meadow plant communities by conducting experiments on the eastern edge of the Qinghai-Tibet Plateau with different concentrations of phosphorus addition (Ca(H₂PO₄)₂, 40, 80, 120 g·m⁻², labeled as P1, P2, and P3, respectively), silicon addition (4 g·m-2 H4SiO4, labeled as Si), and combined phosphorus-silicon treatments (labeled as P1Si、P2Si、P3Si). Important findings Phosphorus addition significantly promoted the abundance and biomass of grass and sedge functional groups, but inhibited the abundance and biomass of forb species, leading to a significant decline in species richness and the Shannon-Wiener index. Silicon addition improved community evenness, asynchrony, and temporal stability. Compared with the same concentration of phosphorus addition alone, combined phosphorus and silicon addition partially alleviated the negative impact of phosphorus addition on community diversity, and their interaction was significant. Path analysis results indicated that phosphorus addition had a significant direct negative effect on community temporal stability. Silicon addition, conversely, showed a significant direct positive effect on community temporal stability. Regarding indirect pathways, phosphorus addition significantly reduced species diversity, and the decline in species diversity was significantly correlated with a decrease in community stability. Silicon addition significantly increased community evenness, and the enhancement of community evenness was significantly and positively correlated with increased stability. Therefore, silicon addition not only directly promoted stability but also produced beneficial indirect effects by enhancing community evenness. Thus, silicon plays a buffering role in maintaining species diversity, mitigating phosphorus-induced community structure simplification, and enhancing ecosystem stability and asynchrony. This study reveals the potential function of silicon in regulating the plant community structure and stability of alpine meadows, providing a theoretical basis for the ecological restoration and nutrient management of degraded meadows in this region.

Key words: silicon addition, community stability, phosphorus addition