Effect of plateau pika disturbance on soil organic carbon storage in alpine grasslands is more strongly associated with grasslands degradation levels than pika density

The influence of plateau pika (Ochotona curzoniae) disturbance on soil organic carbon (SOC) storage in alpine grasslands remains controversial. It is unclear whether grassland degradation levels contributed to these differences. In this study, we examined variations in soil physicochemical properties, SOC content and its components in both control and pika-disturbed alpine grasslands across varying degradation levels. The primary objective is to elucidate the contributions of degradation levels, SOC component and the extent of pika disturbed areas to the impact of pika disturbance on SOC storage. The results indicate that, (i) pika disturbance increases SOC content by 10.1–23.8 % and 13.3–28.6 % in lightly (LDM) and moderately (MDM) degraded grasslands at 10–45 cm, while decreases it by 10.1–18.3 % in severely degraded grassland (SDM) at 0–20 cm. Structural equation models (SEM) analysis suggests that, the total effect of grassland degradation levels is more than twice of pika density on SOC content. (ii) Pika disturbance induces greater changes in particulate organic carbon (POC) content compared to mineral-associated organic carbon (MAOC), resulting in a more pronounced increase in its total effects on SOC content, particularly in MDM. (iii) The impacts of pika disturbance on SOC content and its components differ between pika burrow holes and tunnels, with the decreases predominantly observed in burrow holes rather than tunnels. These findings suggest that the effects of pika disturbance on SOC storage are more strongly associated with grassland degradation levels than with pika density. The management strategies for plateau pika in alpine grasslands should prioritize addressing degradation levels over exclusively focusing on reducing pika density.