Density‐Dependent Response of Alpine Meadows to Plateau Zokor Disturbance on the Tibetan Plateau: Nonlinear Relationship and Ecological Thresholds

ABSTRACT

The plateau zokor ( Eospalax baileyi ) is a keystone subterranean rodent species in the alpine meadows of the Qinghai‐Tibet Plateau, and its burrowing and foraging activities exert complex dual effects on grassland ecosystems. Quantifying the relationship between zokor bioturbation and vegetation, ground‐surface and community characteristics, and identifying the ecological management threshold are crucial for sustainable land management. This study selected 21 typical alpine meadow sites along a disturbance gradient on the eastern Qinghai‐Tibet Plateau. We used unmanned aerial vehicle remote‐sensing to extract new mound density as a proxy for relative disturbance intensity and integrated multiple ground‐surveyed indicators into a grassland degradation index, so as to evaluate the association between overall grassland condition and disturbance intensity and to identify the key ecological management threshold. The results showed that vegetation cover and mean height declined linearly and the proportion of bare ground increased linearly with increasing disturbance intensity; community composition exhibited an inverted U‐shaped pattern in species richness and a U‐shaped pattern in the proportion of poisonous plants, whereas aboveground biomass and the proportion of edible forage showed no significant relationship with relative disturbance intensity. Furthermore, a nonlinear relationship was detected between zokor disturbance and the grassland degradation index, and we identified 166 new mounds·ha ⁻¹ as the ecological management threshold for plateau zokors; above this threshold, the tendency of grassland condition toward degradation became more pronounced, with surface denudation and deterioration of community composition emerging as the primary constraints on overall grassland condition. This study provides a quantitative basis for shifting alpine meadow management from conventional “pest control” toward threshold‐based adaptive management, and offers a reference for identifying and regulating bioturbation thresholds in other vulnerable ecosystems.