Ecological restoration processes in pika mounds on the Qinghai-Tibet Plateau

Abstract

Plateau pika activities affect the plant communities and soil properties by feeding, burrowing, and excretion. However, it is unclear how plant communities and soil properties in exposed mounds caused by pika activity recover. We investigated how plant species richness, vegetation biomass, and soil properties recover in pika mounds, which was formed in 2020, four years after the disturbance was ceased (2020−2023) in an alpine meadow on the Qinghai-Tibet Plateau. The results showed that 1) total carbon (TC), total nitrogen (TN), carbon nitrogen ratio (C:N), and soil water content (SWC) were significantly decreased while soil pH was significantly increased under pika mounds, whereas ammonia nitrogen and nitrate nitrogen showed no difference with control; 2) the decline in soil C:N and TN reduced grass and sedge biomass, respectively, while the increase in soil pH enhanced the forb biomass in pika mounds after 4-year recovery; 3) the decreased sedge and grass biomass outweighed the increased forb biomass, leading to the decline of aboveground biomass; the belowground biomass was also lower than ambient control after 4-year recovery; 4) although species richness increased by 22.00 % in exposed mounds after 4-year recovery, it did not recover to control level. The result suggests that neither soil properties nor plant communities in exposed mounds recovered to control levels after 4-year of recovery. The findings provide an extensive understanding of the restoration process in newly formed pika mounds, which is conductive to restoration and management of degraded grassland.