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Plateau pika (Ochotona curzoniae) is an endemic mammal in the Qinghai-Tibetan Plateau, and its activities create extensive disturbances on vegetation and soil of alpine meadow. Field surveys at two sites were conducted to determine the effects of plateau pika disturbances on important soil factors and plant biomass of vegetated land, and their relationships of the same alpine meadow type. Our study showed that plateau pika disturbances significantly increased soil organic carbon, soil total nitrogen, graminoid biomass and the number of plant species, and significantly decreased soil moisture and forb biomass, although they had no significant impacts on soil total phosphorus, soil total potassium and total biomass on vegetated land. Our study further showed that soil organic carbon, soil total nitrogen, graminoid biomass and the number of plant species were much higher at intermediate disturbance intensities than those at low and high disturbance intensities in the disturbed areas, and soil moisture showed a decreasing trend with the increase of disturbance intensity. Plateau pika disturbances altered the contribution of some important soil nutrients and moisture to plant biomass, and had different impact on the best models between plant biomass (total biomass, graminoid biomass and forb biomass) and predominant soil factors. Our results demonstrated that the optimal disturbance intensities of plateau pika were beneficial to alpine meadow. These results highlighted the influence of the presence of plateau pika and its disturbance intensity on key soil nutrients and plant productivity on vegetated land of the same alpine meadow type, which will help us better understand the role of plateau pika in the alpine meadow ecosystem.

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Small burrowing herbivores create extensive disturbances to grassland soil, which may change carbon cycling. We focused on the plateau pika (Ochotona curzoniae) to simultaneously investigate the responses of the soil organic carbon (SOC) and soil inorganic carbon (SIC) stocks of alpine meadows to the disturbance caused by this small burrowing herbivore and its disturbance intensity at the plot scale across five sites on the Qinghai‐Tibetan Plateau. The percentage of bare soil area in a disturbed plot was used as a proxy for the disturbance intensity of plateau pikas. Our study found that the disturbance by plateau pikas reduced the SIC stock and increased the SOC stock, whereas it had no effect on the soil total carbon (STC) stock. Our study also found that the SOC and STC stocks were higher at intermediate disturbance intensities of plateau pikas, whereas the SIC stock showed a decreasing trend as the disturbance intensity of plateau pikas increased. Our findings suggest that intermediate disturbance intensities of a small burrowing herbivore (plateau pika) improve soil quality by increasing the SOC stock and benefit soil carbon sequestration by increasing the STC stock.Highlights Explored the SIC and SOC stocks simultaneously in relation to the disturbance by a small burrowing herbivore. Soil carbon stocks were evaluated at plot scale across five sites. SIC and SOC stocks responded differently to the disturbance by plateau pika and its disturbance intensity. The intermediate disturbance intensities were good for the soil quality and soil carbon sequestration.

The plateau pika (Ochotona curzoniae) is known to influence the plant diversity and biomass of the alpine meadow, and it is regarded as a pest. The species has been subject to extensive controls without a clear target density in the Qinghai-Tibetan Plateau. We investigated the effects of different plateau pika disturbance levels on plant composition, species diversity and biomass. The density of active burrow entrances was used as an index of disturbance levels I, II, III and IV (corresponding to 8, 19, 27 and 39 active burrow entrances per 625 m 2 ). We found that the plant community composition differed with different disturbance levels. The plant replacements were mainly related to associate plants rather than dominant plants. With the increase in the plateau pika disturbance levels, the plant cover decreased, and the plant height first increased and then decreased. The plant evenness index was higher in the levels II and III disturbance conditions, while the plant diversity index and plant richness index were highest in the level IV disturbance condition. The disturbance levels had no effect on the total plant biomass; however, the intermediate disturbance levels (II and III) increased the palatable plant biomass. The total plant biomass was mainly dependent on the unpalatable plant biomass. The total plant biomass showed a positive correlation with the richness index and a negative correlation with the evenness index. The palatable plant biomass showed a positive correlation with the evenness index and a negative correlation with the richness index. These results imply that the intermediate disturbance levels are beneficial to livestock production as they increase the alpine meadow quality, and the higher disturbance level is better for plant diversity conservation in the alpine meadows of the Qinghai-Tibetan Plateau.

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