天目山森林土壤的水文生态效应

天目山主峰海拔高逾1500m，由山麓到山顶形成四个森林植被垂直带谱，包括七个森林类型，即常绿阔叶林、常绿落叶阔叶混交林、落叶阔叶林、山顶灌丛－矮林、针叶林、针阔混交林和竹林。调查研究表明，各类型森林枯落物（层 ）的现存量，组成成分、持水率、持水量等均不相同，森林土壤（矿质层）的主要物理性质因森林类型而不同，并均随着土壤的深度呈某种规律性变异。森林土壤的持水量主要受土壤孔隙度的影响。在天目山地区，森林土壤的持水量较非林地土壤（荒草地）为高；落叶阔叶林类型的土壤持水量，常较针叶林类型为高。

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.