Effects of different grazing intensities on plant seedling regeneration in an alpine meadow

Long-term overgrazing can significantly change the plant community structure of alpine meadows, and in serious cases may lead to grassland degradation. The grassland ecosystem has the ability of self-recovery, and seedling regeneration plays an important role in maintaining its ecological stability. Exploring the effects of different grazing intensities on the seedling community holds significance in guiding sustainable utilization of alpine meadow grassland resources. In this study, a typical alpine meadow plant community in Guinan County, Qinghai, China, was used as the research object to explore the effect of grazing on seedling regeneration. Through the implementation of different intensity grazing models enclosed grassland (EG), light grazing (LG), moderate grazing (MG), and heavy grazing (HG), the number and density of seedlings, and the physical and chemical properties of soil were investigated. The results showed that compared with EG, grazing significantly increased the number and density of seedlings in the grassland (P < 0.05) as well as the α diversity index of grassland seedling community (P < 0.05), and the dominance of compositae and weeds was found to be higher than that of Poaceae and Leguminosae. On the other hand, grazing led to the loss of nutrients in the surface soil (0－10 cm) of the grassland, but the contents of total nitrogen and total phosphorus in the soil were significantly negatively correlated with the community diversity of grassland seedlings. A downward trend was seen with a certain degree of degradation in species composition and density of seedlings in HG grassland. This study shows that grazing can promote the establishment of seedlings in alpine meadows and help maintain grassland ecological stability depending on grazing intensity. LG and MG were found to be conducive to the sustainable utilization of grassland resources, while HG was seen to inhibit the growth of seedlings and cause grassland degradation.