原生亚热带山地常绿阔叶林下土壤侵蚀量的研究

采用量水堰方法测定了一个原生常绿阔叶林小流域的侵蚀量。该小流域在当地属较陡的类型,面积14.4ha。1986至1990年的观测结果表明,每年沉积在量水堰静水池和沉砂池中的沉积物约为530至1820kg,每年由堰口流出的侵蚀量估算为500至2950kg,故每年的全部侵蚀量约为1030至4770kg,平均每公顷约为70至330kg,其中有机物约占15％。根据观测结果分析,每年侵蚀量的多少,主要决定于降水强度。遇有暴雨和大强度降水较多的年份,侵蚀量明显增大。此外,侵蚀量主要来自地表流。由于常绿阔叶林下土壤的透水性很好,估计小流域97％的降水是先渗透到土壤中,故其侵蚀量很小。

A STUDY ON THE AMOUNT OF SOIL EROSION UNDER THE PRIMARY SUBTROPICAL MOUNTAINOUS EVERGREEN BROAD-LEAF FOREST

We apply the gaging weir approach to make the research on the amount of soil erosion under the original subtropical mountainous evergreen broad-leaf forest of a small watershed in the Jiu-lian mountain reserve,Jiangxi province.This small watershed is of the steeper type and its area is 14. 4 ha. In the five years from 1986 to 1990 , we got some results of the observation and survey of the soil erosion in the region. The annual sediment deposited in the silt trough of the gaging weir is about 530-1820 kg. The annual solid flow from the notch of the weir is about 70-330 kg/ha,and the organic matter makes up about 15% of the whole erosion amount.We make an analysis on the basis of the results of observations, and find out that the annual erosion amount mainly depends on the precipitation intensity. The annual erosion amount will markedly increase in the year when there are rainstorms and more intensive rains. Because soil erosion is mainly caused by surface flow, but the water permeability of the soil under the evergreen broad-leaf forest is very good.and about 97% of the precipitation in the small watershed can permeate into the soil,therefore the erosion amount under the evergreen broad-leaf forest in the small watershed is little.