THE PRELIMINARY INVESTIGATION ON THE EFFECTS OF FOREST SOIL HYDRO-ECOLOGY IN TIANMU MOUNTAIN

Tianmu Mountain, with its peak over 1500m above sea level, is the sources and water-shed of many streams of Yangtze River and Qiant-ang River. There are four vertical forest vegetation zones, which include seven forest types at different altitudes, from the foot to the top of Tianmu Mountain. The seven forest types are: evergreen broad-leaf forest, evergreen and deciduous broad-leaf mixed forest, deciduous broad-leaf forest, hill-top shrub and dwarf forest, needle and broad-leaf mixed forest, and bamboo grove.The characteristics of soil in the forest types are different. The investigation and tests showed that the standing crops, component, water-holding capacity and its percentage are all different in their litter (layers). The litter plays an important role in forest soil hydro-ecology. The physical properties of the forest soil, such as specific volume, specific weight, natural moisture content, capillary water, porosity, etc., vary with the forest types. The water-holding capacity of forest soil is higher than that of non-forest land (such as grassland). The deciduous broad-leaf forest always holds more water in the soil than the evergreen needle forest does.The abundant annual precpitation of Tianmu Mountain forest region, satisfies the needs of the forest vegetation and the evapo-transpiration of the soil surface. The forest soil hydro-ecological effect in Tianmu Mountain is essential to the preservation of natural balance.