Plateau Pika (Ochotona curzoniae) Disturbance Alters Soil-Microbe-Enzyme C–N–P Stoichiometry and Drives a Shift From N- to P-Limitation in Alpine Meadows on the Qinghai-Tibet Plateau

Abstract

Soil-microbe-enzyme C–N–P stoichiometry is a key indicator of nutrient cycling and ecosystem resilience. This study examines its response to plateau pika (Ochotona curzoniae) disturbance in alpine meadows on the Qinghai-Tibet Plateau. The results demonstrated that plateau pika disturbance significantly enhanced soil organic carbon (SOC) by 28.97%, soil total nitrogen (STN) by 8.25%, and soil total phosphorus (STP) by 9.15%. Microbial biomass C (MBC), and N (MBN) increased by 5.60% and 6.30%, respectively. Enzyme activities of β-1,4-glucosidase (BG), N-acetyl-β-D-glucosaminidase (NAG), and leucine aminopeptidase (LAP) were also elevated in disturbed plots compared to undisturbed plots. Soil C:N, C:P ratios, and enzyme N:P ratio were 19.62%, 19.65%, and 4.48% higher, respectively, while MBN: MBP ratio was 21.63% lower in disturbed plots. Additionally, the soil C:N imbalance increased, and C:P homeostasis became weakly homeostatic (H′ = 2.38) under plateau pika disturbance. Moreover, STP and underground biomass were identified as key factors regulating soil-enzyme C–N–P stoichiometry in undisturbed plots, while SOC was the strongest factor associated with microbe C:N:P stoichiometry in disturbed plots. These results indicate that plateau pika disturbance drives a shift in microbial metabolic strategies toward C utilization and progressively transforms alpine meadow soils from N- to P-limitation with increasing disturbance intensity. Therefore, this study proposes targeted N supplementation under low disturbance intensity, whereas P fertilization is recommended under high disturbance intensity to mitigate nutrient limitation.