Spatial variation of soil hydrologic-physical properties within the small watershed of Fenshuilinggou in Liupan Mountains,Northwest China
WANG Die-Gao-； Wang-Pan-Hui-； Xie-Shuang-Chi-； Mo-Fei-； Xu-Peng-Chao-； Xiong-Wei-； Shi-Zhong-Jie
1.The Research Institute of Forestry Ecology,The Forestry Academy of Chongqing,400036,Chongqing;2.The Research Institute of Forestry
Ecology,Environment and Protection,Chinese Academy of Forestry,100091,Beijing;3.Forestry College of Guizhou University,550025,Guiyang;4.The Research Institute of Tropical Forestry,Chinese Academy of Forestry,510520,Guangzhou:China
Abstract：The spatial variation of soil physical properties within a small watershed is influenced by the environmental factors such as landform and vegetation,especially strongly influenced by the landform.The data analysis of soil physical properties collected from 118 sample sites in the small watershed of Fenshuilinggou in the Liupan Mountains of northwest China shows: 1) The soil bulk density and volumetric content of rock fragment increase with soil depth,while the saturation water content,capillary water content,total porosity,capillary porosity and non-capillary porosity decrease with soil depth;2) There is a big difference of soil physical properties among vegetation types.Within the 7 types of forest vegetation investigated(forest of <i>Pinus armandii</i>,forest of <i>Larix principis-rupprechtii</i>,forest of <i>Betula platyphlla</i>,forest of <i>Quercus liaotungensi</i>,mixed forest of <i>Pinus armandii</i> and <i>Betula albo-sinensis</i>,mixed forest of <i>Tilia paucicostata</i> and <i>Quercus liaotungensis</i>,mixed bushes),the soil bulk density in layer 0-20 cm and 0-60 cm is lowest for the conifer-broadleaf mixed forest of <i>Pinus armandii</i> and <i>Betula albo-sinensis</i>,highest for the mixed bushes,and in the middle for the pure conifer forests and broadleaf forests.Correspondingly,the soil water carrying capacity of soil layer 0-60 cm is largest in the conifer-broadleaf mixed forest,lowest in the bushes,and in the middle for those pure conifer or broadleaf forests.3) There is a difference of soil physical properties among slope aspects.All the soil physical properties investigated for the layer of 0-60 cm are basically better in north slope,bad in south slope,and in the middle for the west and east slopes.4) The slope position also has an effect on soil physical properties,taking the soil bulk density of soil layer of 0-20 cm as an example,it is highest at slope top and slope foot with the same value of 0.93 g/cm<sup>3</sup>.In general,the soil physical properties on the slope are better than those at the slope top and slope foot.5) There is a marked correlation between the soil physical properties and landform characters(relative elevation,slope aspect,slope position,and slope gradient),and a linear regression equations between them were established.
2008, Vol. 6 
