本研究以青海湖流域高山嵩草草甸生态系统为研究对象，分析不同坡向植被、土壤碳密度的变化趋势，探究土壤理化性质、群落结构对生态系统碳密度的影响，以期为高寒草甸碳库研究提供科学参考。通过野外实验和室内分析，测定了青海湖流域不同坡向高山嵩草草甸的地上和地下碳密度、土壤碳密度（包括土壤无机碳、颗粒态有机质（Particulate organic matter，POM）、矿质结合态有机质（Mineral-associated organic matter，MOM）和热水溶性有机碳（Hot water-extractable carbon, HWC））、主要植物群落结构特征和土壤理化性质。结果表明：1）高山嵩草草甸的地上碳密度、植物地下碳密度表现为阴坡>阳坡，而不同坡向间0-10cm的植物地下碳密度阴坡＞阳坡，10-20,20-30cm均表现为阳坡大于阴坡；2）土壤无机碳密度则表现为阳坡>阴坡，土壤颗粒态有机质（Particulate organic matter，POM）、矿质结合态有机质（Mineral organic matter，MOM）、热水溶性有机碳表现为阴坡>阳坡。不同坡向间0-10,10-20cm的热水溶性有机碳为阴坡>阳坡，20-30cm为阳坡>阴坡，差异不显著；3）植物地下碳密度、POM和热水溶性有机碳随土层深度的增加逐渐降低，土壤无机碳含量随土层深度的增加逐渐增加，MOM则随着土层深度的增加先增加后降低。随着土壤比重的降低，植物地下碳密度、POM含量和热水溶性有机碳含量会增加，土壤无机碳含量会降低，随着砾石含量的增加植物地下碳密度、POM含量和热水溶性有机碳含量降低，MOM含量和土壤无机碳含量均增加；4）物种数、Shannon-Wiener多样性指数、均匀度指数和优势度指数为阴坡＞阳坡。所以说，坡向会通过影响土壤理化性质和植物群落，导致不同坡向下高山嵩草草甸生态系统碳密度出现差异。

Influence of slope aspect on carbon density and its influencing factors of Kobresia pygmaea meadows was analyzed in Qinghai Lake watershed, in order to provide reference and scientific basis for the research of alpine meadow carbon pool. In this study, we evaluated the effect of aspect on the above-ground biomass carbon density, below-ground carbon density, soil carbon density, related plant community biodiversity and soil physicochemical properties. The above-ground biomass carbon density was higher on the sunny slope than that on the shady slope, the below-ground biomass carbon density was similar between sunny and shady slopes. The below-ground biomass carbon in the 0-10cm soil layer was higher on the shady slope than that on the sunny slope, while which in the 10-30cm soil layer was higher on the sunny slope than that on the shady slope. Soil inorganic carbon was higher on the shady slope than that on the sunny slope, particulate organic matter（POM）, Mineral organic matter (MOM), hot water-extractable carbon(HWC) was higher on the sunny slope than that on the shady slope. Soil inorganic carbon in the 0-30cm soil layer was higher on the sunny slope than that on shady slope, POM and MOM in the 0-30cm soil layer were higher on the shady slope than that on sunny slope, but the difference in POM wasn’t significant. HWC in the 0-20cm soil layer was higher on the shady slope than that on the sunny slope, while in the 20-30cm soil layer was higher on the sunny slope than that on the shady slope, but the difference of HWC wasn’t significant. The below-ground biomass carbon density, POM and HWC gradually decreased with the increase of soil depth, soil inorganic carbon gradually increased with the increase of soil depth, while MOM firstly increased and then decreased with the increase of soil depth. With the decrease of Specific gravity of soil, the below-ground carbon density, POM and HWC increased, while the soil inorganic carbon decreased. With the increase of gravel content, the below-ground carbon density, POM and HWC decreased, while MOM and the soil inorganic carbon increased. The number of species, Shannon-Wiener index, evenness index and dominance index were higher on the shady slope than that on the sunny slope. Together, these results show that aspect plays an important role in the plant community structure and soil physicochemical properties, leading to significant differences in the carbon density of Kobresia pygmaea ecosystem under different slopes.