青海湖流域季节性冻土区坡面土壤有机碳分布特征及其影响因素

以高寒半干旱区青海湖流域季节性冻土为研究对象，通过调查采样和室内分析，研究了坡向和坡位对不同深度土壤有机碳含量分布的影响。结果表明：阴、阳坡有机碳含量均随土壤深度增加而下降，但阳坡下降的幅度（64%）明显高于阴坡（44%）。阴坡土壤有机碳平均含量为81.99 g/kg，大于阳坡（61.84 g/kg）；不同坡位，土壤有机碳分布特征因坡向而异，其中阴坡土壤有机碳平均含量表现为坡下（89.60 g/kg）＞坡中（86.52 g/kg）＞坡上（69.87 g/kg），而阳坡土壤有机碳平均含量表现为坡上（65.71 g/kg）＞坡下（61.42 g/kg）＞坡中（58.39 g/kg）。此外，坡位对不同深度土壤有机碳的影响程度在不同坡向也存在差异。阴坡坡位因子对深层土壤有机碳影响显著，而阳坡坡位因子对浅层土壤有机碳影响显著。一般线性模型结果表明，坡面土壤有机碳含量主要受土层和坡向的影响，可解释74.52%的变异性。

Characteristics of soil organic carbon distribution and its controlling factors on hillslope in seasonal frozen area of Qinghai Lake Basin

The seasonally frozen ground in Qinghai Lake Basin in alpine and semi-arid region was studied in this paper. The effects of slope aspects and positions on distribution of soil organic carbon (SOC) content at different depths were studied by means of field investigation, sample collection, and lab analysis. The results showed that the SOC content of both shady and sunny slopes decreased with the increase of soil depths, but the decrease range of the sunny slope (64%) was significantly higher than that of the shady slope (44%). The average SOC content on the shady slope was 81.99 g/kg, higher than that of the sunny slope (61.84 g/kg); the distribution characteristics of SOC content in different slope positions varied with slope aspects. On the shady slope, the average SOC content showed a trend of lower slope (89.60 g/kg) > middle slope (86.52 g/kg) > upper slope (69.87 g/kg); while on the sunny slope, the average SOC content tended to be upper slope (65.71 g/kg) > lower slope (61.42 g/kg) > middle slope (58.39 g/kg). In addition, the effect of slope positions on SOC content at different depths also varied in different slope aspects. The shady slope factor had a significant effect on SOC content at deep soil layers, while the sunny slope factor had a significant effect on SOC content at shallow soil layers. The results of general linear model showed that the SOC content in slopes was mainly affected by soil depths and slope aspects, which could explain 74.52% variability of SOC content.