Response of vegetation community and soil properties of grassland to different density gradients of Ochotona curzoniae in the Sanjiangyuan Region

In order to explore the impact of rodents on alpine grassland ecosystems, we investigated the effect of different densities of plateau pika (Ochotona curzoniae) in the Sanjiangyuan (Source of the Three Rivers) Region in 2016 on different vegetation characteristics (aboveground biomass, underground biomass, species richness) and soil properties. The testing results indicate that the vegetation species richness decreased as pika density increased, and the plant community composition of meadow could be changed by an appropriate density of pika. In addition, as pika density increased, aboveground biomass and underground biomass decreased, but the root: shoot ratio increased. And there were significant differences for soil properties at different soil depths. Most soil properties showed a fluctuating downward trend at the soil depth of 0–20 cm as pika density increased. The soil properties of the areas without pika were significantly different to the areas with high and low densities of pika. Besides, according to the correlation analysis, it is concluded that soil factors are the main drivers of the changes in root: shoot ratio. The findings highlighted that certain levels of pika populations can change the plant community structure and improve soil nutrients, and consequently contribute to the sustainable development of the grassland ecosystem.