Effect of grazing management strategies on the vegetation parameters and soil nutrients in alpine Kobresia pygmaea meadow on the northeastern Qinghai–Tibetan Plateau

Abstract

Understanding the impact of grazing management strategies on alpine meadow is of fundamental importance for grassland conservation. However, the vegetation and soil properties in response to the different grazing management strategies implemented on Kobresia pygmaea meadow remains elusive. In this study, a medium-term field experiment with three grazing management strategies (free grazing, FG; no grazing, NG; and reduced grazing, RG) was conducted. The results revealed that the total aboveground biomass (AGB), vegetation cover and litter biomass increased significantly under NG treatment, whereas the total belowground biomass (BGB) decreased significantly in NG plot. Furthermore, the responses of plant functional groups to different grazing management strategies were varied. The AGB of grass increased remarkably under NG treatment compared to FG plot, whereas there were no obvious change in AGB of the sedge, legume, and forb groups. The concentrations of the soil available phosphorus (AP) and ammonia nitrogen (NH4+-N) of RG and FG were considerably different at the 0–5 cm soil layers. In contrast, the soil C:N ratios in all soil layers were similar among the three grazing management strategies. It is worth noting that the soil AP concentration was positively correlated with the total AGB. More importantly, the results supported the functional equilibrium hypothesis for AGB versus BGB, which is based on the unique biological characteristics of K. pygmaea meadow. Our study provides valuable insights into the response of alpine meadow to grazing management strategies and can thus provide guidance for designing management strategies for degraded alpine meadow.