Plateau pika interferes with the relationship between biodiversity and ecosystem multifunctionality in alpine meadows

Abstract

Plateau pikas alter alpine meadow biodiversity and ecosystem functions via foraging, burrowing, and excretion. While plant and soil biodiversity synergistically regulate ecosystem multifunctionality (EMF), their relative contributions under varying pika densities remain unclear. Through a 5-year study on the Tibetan Plateau's eastern edge, we assessed pika disturbance effects on multi-trophic biodiversity (plants, earthworms, ciliates, fungi, bacteria) and EMF (biomass, soil nutrients). Results showed plant diversity exerted stronger EMF control than soil biodiversity across burrow density gradients. At 550 burrows/ha, EMF drivers shifted: soil biodiversity maintained positive correlations in low-density areas, while plant diversity dominated in high-density zones. Structural equation modeling further revealed density-dependent divergence in regulatory pathways—both plant and soil biological diversity showed significant positive correlations with pika density under low-density conditions, but these relationships inverted to negative correlations in high-density environments. In conclusion, plateau pika densities reaching 550 burrows/ha trigger a shift in dominant drivers of EMF. We recommend maintaining populations below this critical threshold to sustain functional gains while prioritizing plant diversity conservation in density-exceeding areas, thereby balancing ecological services and productivity in alpine meadows.