LAUSR

This research was designed to explore the variation characteristics of soil C:N:P stoichiometry and enzyme activity in the Qilian Mountains different grassland types. Thus, 7 grassland types (Upland meadow: UM, Alpine meadow: AM, Temperate steppe: ST, Alpine steppe: AS, Temperate Desert Steppe: TDS, Temperate Desert: TD, Alpine desert: AD) of Qilian Natural Reserve were selected to analyze the variation characteristics of soil enzyme activities and stoichiometry of different grassland types and its relationship with environmental factors. The study indicated that the C/N, C/P, and N/P of different grasslands ranged from 5.08 to 17.35, 2.50 to 72.29, and 0.53 to 4.02.The ranking of different types grassland for the C/N was TS ≥ AM ≥ UM ≥ AS ≥ TDS > AD > TD, and the changing pattern of C/P and N/P is similar to that of C/N. The ranking of different types grassland for the urease enzyme activity was UM ≈AS > AD ≈TDS ≈TS ≈AM > TD, and TS ≈AM ≈UM ≈AS ≈AD > TDS > TD for alkaline phosphatase enzyme activity, and AS ≈AM ≈TS ≈TDS≥UM ≥TD ≈AD for catalase enzyme activity. Based on N/P ratio and RDA analysis, nitrogen was the main factor limiting the grassland productivity, and pH, TN, SOC, Richness index and Simpson diversity index were the main environmental factors affecting the soil C:N:P stoichiometry and enzyme activities. Cluster analysis showed that 7 grassland types were clustered into three categories. In conclusion, the stoichiometric characteristics and soil enzyme activities of different grasslands vary with grassland types. Nitrogen was the main factor limiting the grasslands productivity, and pH, TN, SOC, Richness index and Simpson diversity index were the main environmental factors affecting the soil C:N:P stoichiometry and enzyme activities, and the grassland Qilian Mountain can be managed in the ecological district according to the clustering results. The results of this study can provide data support and theoretical guidance for the scientific management and ecological protection of grassland in Qilian Mountains Reserve.