Abstract: In recent years， global warming has led to severe degradation of alpine grasslands on the Tibetan Plateau. In this study we investigated the soil enzyme activities and their stoichiometric characteristics in different types of alpine grasslands in the Naqu region of Xizang， aiming to understand the soil nutrient status and grassland ecosystem functions. The results show that soil enzyme activities varied significantly among different grassland types （0.5245-20 446 U·g^-1）， with degraded grasslands having lower enzyme activities than non-degraded ones， except for alkaline phosphatase （AKP） and exoglucan β-1，4-glucanase （CBH）. In alpine meadows， the vector angle of soil AKP was greater than 45°， indicating limitation of phosphorus nutrient. Degraded grasslands had higher Enzyme C/P and Enzyme N/P ratios， suggesting microbial limitations of carbon and phosphorus， while Enzyme C/N ratios showed no significant differences. Soil organic carbon （SOC）， total nitrogen （TN）， total phosphorus （TP）， and available phosphorus （AP） contents were the main factors affecting soil enzyme activities. Differences in microbial biomass carbon （MBC） and microbial biomass nitrogen （MBN） contents reflect distinctions in microbial community structure and affect enzyme secretion. The differences in soil nutrient structure among different grassland types directly influenced enzyme secretion， leading to significant differences. In the future， combining soil microbial community composition and functional characteristics could further reveal the mechanisms of soil nutrient cycling and ecosystem function in alpine grasslands on the Tibetan Plateau， providing effective suggestions for grassland management and ecological restoration of degraded grasslands.

Key words: Grassland degradation, Alpine grassland, Soil enzyme activity, Soil enzyme stoichiometry

摘要： 近年来，全球气候变暖导致青藏高原高寒草地退化问题严重。本研究探讨了西藏那曲地区不同类型高寒草地的土壤酶活性及其化学计量特征，以了解土壤养分状况及草地生态系统功能。结果显示，不同草地类型的土壤酶活性差异显著（0.5245~20 446 U·g^-1），退化草地酶活性低于未退化草地[碱性磷酸酶（Alkaline phosphatase，AKP）和外切-β-1，4-葡聚糖酶（Exoglucan β-1，4-glucanase， CBH）除外]。高寒草甸中土壤AKP矢量角度大于45°，表明存在磷养分限制。退化草地酶C/P和N/P较高，微生物存在碳和磷限制，而酶C/N无明显差异。土壤有机碳（Soil organic carbon，SOC）含量、全氮（Total nitrogen，TN）含量、全磷（Total phosphorus，TP）含量、土壤速效磷（Available phosphorus，AP）含量是影响土壤酶活性的主要因素，土壤微生物量碳（Microbial biomass carbon，MBC）和微生物量氮（Microbial biomass nitrogen，MBN）含量差异表征了微生物群落结构的区别，影响酶的分泌。不同草地类型土壤养分结构差异直接影响土壤酶的分泌，导致显著差异。未来结合土壤微生物群落组成及功能特征，可进一步揭示青藏高原高寒草地土壤养分循环及生态系统功能的影响机制，为草地管理及退化草地生态修复提供有效建议。

关键词: 草地退化, 高寒草地, 土壤酶活性, 土壤酶化学计量