Abstract: To evaluate the potential impacts of grazing on grassland soil carbon pools， this study investigated the effects of different grazing intensities on the contents of soil organic carbon （SOC） and its fractions—including particulate organic carbon （POC）， mineral-associated organic carbon， light fraction organic carbon （LFOC）， heavy fraction organic carbon （HFOC）， easily oxidizable organic carbon （EOC）， and dissolved organic carbon （DOC）-in alpine meadows. The results showed that with increasing grazing intensities， the contents of SOC and most of its fractions significantly decreased （except for EOC and DOC）， and the stability of the organic carbon pool declined. Under extreme grazing， SOC and POC contents were significantly reduced by 33.54% and 56.21%， respectively， compared with light grazing. The ratios of EOC/SOC and DOC/SOC exhibited significant fluctuations in response to grazing intensity， making them important indicators for evaluating the impacts of grazing on soil carbon pools in alpine meadows. The contents of SOC and its fractions were significantly correlated with soil total nitrogen （TN） content， bulk density （BD）， and aboveground biomass （AGB）， with TN being the key factor influencing SOC and its fractions. Appropriate grazing intensity is crucial for maintaining and enhancing soil quality and carbon pool functions in alpine meadows， as overgrazing reduces SOC accumulation and stability. This study provides a scientific basis for grazing management and soil organic carbon pool conservation in alpine meadows of the East Qilian Mountains.

Key words: Grazing intensity, Alpine meadow, Soil organic carbon, Organic carbon fraction, Physical-chemical fractionation

摘要： 为评估放牧对草地土壤碳库的潜在影响，研究了不同放牧强度对高寒草甸土壤有机碳（Soil organic carbon，SOC）及其组分颗粒有机碳（Particulate organic carbon，POC）、矿物结合有机碳、轻组有机碳、重组有机碳、易氧化有机碳（Easily oxidation organic carbon，EOC）和溶解性有机碳（Dissolved organic carbon，DOC）含量的影响。结果表明：随放牧强度的增大，土壤SOC及其组分含量显著下降（除EOC，DOC外），有机碳库稳定性降低。SOC和POC含量在极度放牧条件下，比轻度放牧分别显著降低了33.54%和56.21%。EOC/SOC，DOC/SOC占比对放牧强度的响应波动较大，可作为评价放牧影响高寒草甸土壤碳库的重要指标。SOC及其组分含量与土壤全氮含量、容重和地上生物量显著相关，其中全氮是影响SOC及其组分含量的关键因子。适宜的放牧强度对维护和提升高寒草甸土壤质量和碳库功能至关重要，过度放牧降低了SOC积累和稳定性，研究为东祁连山高寒草甸放牧和土壤有机碳库管理提供了科学依据。

关键词: 放牧强度, 高寒草甸, 土壤有机碳, 有机碳组分, 物理化学分组