Effect of fence management on soil phosphorus content in the Alpine grassland in Qinghai-Xizang Plateau

Fences are widely used in grassland management practices, and phosphorus is an essential nutrient for plant growth. It is crucial to investigate the impact and drivers of fence placement on soil phosphorus cycling to evaluate the dynamics of phosphorus in alpine grassland ecosystems. Moreover, there is a lack of systematic research on fence management and soil phosphorus content. To bridge this knowledge gap, 101 articles were selected for a meta-analysis, based on the Web of Science core database and the China Knowledge Network search platform, to explore the responses of soil total phosphorus (STP) and soil available phosphorus (SAP) in different alpine grasslands to fence management measures and fencing years (short-term 1～4 years, medium-term 5～8 years, and long-term 9～30 years). The results showed that: 1) Generally, fencing significantly increased STP, SAP, total nitrogen (STN), organic carbon (SOC), available nitrogen (SAN), and moisture (SM) levels (P < 0.001) but decreased pH and bulk density (P < 0.01). 2) The positive effect of fencing on STP and SAP in the alpine steppe was significantly higher than that on phosphorus content in the alpine meadow (P < 0.001). 3) According to the years of fencing, medium-term and long-term fencing exerted a significant positive effect on STP (P < 0.001), short-term fencing significantly promoted steppe STP, and medium-term and long-term fencing resulted in a decrease in steppe STP. Fencing helped to improve SAP, and medium term exerted the greatest effect of fencing on steppe SAP. 4) The effects of fencing on STP, STN, and SOC varied synergistically. However, soil acidification significantly increased the effect of fencing on STP. The effect of fencing on STP increased significantly with an increase in temperature. In addition, the effects of fencing on SAP and STN were significantly correlated. Our study revealed that reasonable fencing improves soil phosphorus content in alpine grassland ecosystems, and the results provide a theoretical reference for the scientific management of alpine grasslands.