黄土高原土壤养分空间变异的多尺度分析——以横山县为例

Multi-Scale Analysis of Spatial Variation of Soil Characteristics in Loess Plateau——Case Study of Hengshan County

人类干扰所造成的土地利用和植被的镶嵌化分布及地貌特征等影响着土壤养分的空间分异,黄土丘陵沟壑区土壤退化严重,使得土壤特性对其环境因子的变化更加敏感。以横山县为例,从两种尺度上,利用野外调查,实验室分析和典范对应分析(CCA),得到不同尺度下(小流域尺度和县域尺度)土壤理化性质对环境因子的响应。结果表明,坡度是影响土壤养分的重要影响因子,小流域尺度上,坡度和土壤养分、土壤黏粒含量成正相关;县域尺度上,坡度和主要土壤养分等呈负相关。而海拔高度和坡向对土壤养分的影响仅次于坡度,在不同尺度上也有差异。ANOVA分析表明,土壤有机质、总氮、总磷、速效氮和黏粒百分比在两个尺度上的不同土地利用之间差异显著。地形因子和土壤性质的相关分析表明,土壤性质的差异是地形因子和土地利用等外部因子综合作用的结果,而且其作用表现出较大的尺度差异性。

The Loess Plateau with degenerated soil and land use mosaics reveals a highly modified state controlled by human disturbance and topographical fluctuation, surface soil characteristics in this region are particularly sensitive to site variables and land use change. Taking Hengshan County as a case, the relationships of land types, soil properties and topography were analyzed at two different scales using CCA method. CCA showed that slope was a dominant factor influencing soil properties at both scales. Elevation and aspect was the second important features at county and catchment scale, respectively. ANOVA analysis showed that there existed significant differences in SOM, TN, TP, AN, AP and clay % between land uses. Further study using linear correlation compared the differences of effect of environmental variables on soil properties at two scales. The study indicated that soil variations are a result of comprehensive external effect of topography and land use, Also the effects exhibit different at various scales.