This study takes the dynamic characteristics of soil moist ure of a whole year on Zanthoxylum Forest land in Huajiang karst valley

Guizhou Province as the overall objective.The relationships between soil water content and soil structure

vegetation hararteristics

and the dynamics of soil moist ure in different soil layers are analyzed and the change zones of soil water content in vertical direction are divided.Results indi- cate that water holding capacity of topsoil is higher than that of subsoil.The actual water content on forest land is higher than fallow land

and in deeper soil

higher than surface soil.Soil water content wit hin topsoil changes fastest due to the effects of evaporation and precipitation and it follows by intermediate layer and deepest layer due to the effects of transpiration and soil struct ure

respectively.Vertical change zone of soil moisture can be divided as follow: 0-20 cm is the rapidly changing layer

20-50 cm is the transitional layer

and >50 cm is the stable layer.