黄土高原沟壑区小流域土壤有机碳空间变异

Spatial Variability of Soil Organic Carbon at Small Watershed in Gully Region of Loess Plateau

通过对砖窑沟流域不同地貌部位62个点的取样分析,运用地统计学方法研究了流域土壤有机碳的空间变异性特征,初步探讨了影响空间变异的复杂因素。结果表明:流域内土壤有机碳非常低,存在土壤养分贫瘠化现象。各层土壤有机碳含量的变异为中等程度,该变异主要是由空间自相关部分引起的。同层次内,沟坝地土壤有机碳含量比梁峁地高。垂直剖面上,土壤有机碳含量随深度增加而减少,表层含量值明显高于下部各层,60cm以上含量值随深度增加递减迅速,60cm以下含量值变化不大。不同地貌部位剖面土壤有机碳含量的变幅是:在80cm以上,沟坝地明显大于梁峁地;80cm以下,二者大体相当。土壤有机碳含量在空间上的分异主要受土壤动植物在土体中的分布、土壤含水量、水土流失及人类生产活动等因素的影响。

The 62 observed points were made in Zhuanyaogou watershed in gully region of Loess Plateau. Spatial variability of soil organic carbon (SOC) content were analyzed by geostatistics approach. The complex factors affected spatial variability of SOC were preliminarily discussed. The results indicated that the SOC contents were very low in the studied watershed. The variability of SOC at different soil layer belonged to the middle intensity and was contributed to the influencing of the correlation rather than of the random. The SOC contents in the gullies were higher than those on the tops of the hills at the same soil layer. With the increasing of depth the SOC contents decreased and were higher obviously in the surface soil than those in the other layers. The change quantity of the profile SOC content on the tops of the hills were larger than that in the gullies. The possible factors of influence on the distribution of SOC were soil life, soil water content, soil and water loss and human activities.