六盘山小流域地形、植被特征与土壤水文物理性质的关系

利用多元统计方法,分析了六盘山分水岭沟小流域107个样地的地形、植被特征与土壤水文物理性质的关系。结果表明:饱和持水量、总孔隙度、毛管持水量、容重、石砾体积含量、非毛管孔隙度可作为土壤水文物理性质类型划分的6项重要指标,同时土壤毛管持水量还是一个敏感指标。将所有调查样地划分为土壤物理性质组间差别较大但组内接近的3组样地,发现各组样地的植被类型相近。土壤水文功能最好的第III组是以桦树和山杨为主的天然阔叶次生林样地,其主要分布在阴坡、中坡位;华北落叶松人工林为第Ⅱ组,其土壤水文功能次之;土壤水文功能最差的第Ⅰ组多是位于陡坡悬崖的华山松天然林及杂灌丛样地。土壤孔隙性受到地形和植被特征的共同影响,影响显著的地形特征主要是相对高程、坡向和坡位;植被特征主要是胸径、乔木高度和灌木层盖度。

Relationships of landform and vegetation characters with soil hydrophysical properties in a small watershed of Liupan Mountains, Northwest China

Based on the investigation data from 107 sampling plots in a small watershed of Fenshuilinggou in the Liupan Mountains of Northwest China,and by using multivariate statistical analysis,this paper analyzed the relationships of landform and vegetation characters with soil hydrophysical properties in the watershed.Soil water-holding capacity,total porosity,capillary water-holding capacity,bulk density,volumetric fragment content,and non-capillary porosity were considered as the important soil hydrophysical parameters for classifying soil hydrophysical properties,and soil capillary water-holding capacity was a sensitive parameter.The sampling plots were classified into 3 groups,with great differences in soil hydrophysical properties and vegetation types.Group III had the best soil hydrophysical properties,which was covered by the secondary broad-leaved forests mainly composed of birch(Betula spp.) and poplar(Populus davidiana) and mostly located on the middle section of shady slopes.Group II had relatively good soil hydrophysical properties,which was covered by Larix principis-rupprechtii plantation.Group I had the worst soil hydrophysical properties,which was covered by the natural forests mainly composed of Pinus armandii or shrubs and mostly located on steep slopes.The soil porosity was controlled by landform and vegetation characters.The most important parameters of landform affecting the soil porosity were relative elevation,slope position,and aspect,and the most important vegetation parameters affecting the soil porosity were DBH,tree height,and shrub layer coverage.