黄土丘陵区县域农田土壤有机碳空间变异性——以甘肃庄浪县为例

Spatial variation of soil organic carbon of croplands in hilly Loess Plateau region of China——A case study in Zhuanglang County,Gansu Province

运用地统计学和GIS相结合的方法,研究了黄土丘陵区县域尺度农田土壤有机碳空间变异性及其影响因素。结果表明,1)研究区土壤有机碳含量处于较低水平,平均值为8.28g/kg,变异系数为18.8%,属于中等变异程度。2)有机碳变异函数的理论最佳模型为指数模型,块金值与基台值之比为9%,表明有机碳含量具有强烈的空间相关性,空间相关距离为2250 m,大于采样间距400 m。普通Kriging插值表明土壤有机碳含量整体上呈现东部比西部高、北部比南部高,西部区域斑块状的分布。3)影响该区域土壤有机碳空间变异的主要因素是海拔和土壤类型,坡向及土壤侵蚀程度等,海拔对有机碳空间变异性的贡献率为82.27%,土壤类型为13.10%,坡向和土壤侵蚀程度为4.54%。

The spatial variation of soil organic carbon （SOC） of croplands and its influencing factors at county scale were studied in Zhuanglang County in southern Gansu Province by using a geo-statistics method combined with Geographic hfformation System （G1S）. The results show that the SOC are low with a mean value of 8.28g/kg, and the coefficient of variation of SOC is 18.8%, which expresses a medium spatial variation. The result of semi- variograms indicates that the rate of nugget to sill is 9% showing a strongly spatial self-relativity of SOC in this area. The range of spatially dependent for SOC is 2250 m. The Kriging spatial interpolation at county scale show that the SOC contents in the north part are higher than those in the south part, the SOC contents in the west part are higher than those in the east part, and some high values are in patch forms in the west part. At county scale the main influencing factors for the spatial variability of farmland SOC are altitude and soil type, and altitude could explain 82. 27% of variability, soil type 13.18%, aspect and soil erosion degree 4. 54%.