The Background Value and Ecological Effect of Water Quality of Tropical Forest Catchment in Jianfengling, Hainan Island

The water quality and ecological effect of tropical forest watershed were studied using the located and more watershed measuring in Jianfengling. The measured results in the 41 forest watersheds with 4 indexes of water quality show that there is high quality water in the forest watershed that is a fine natural water. The effects on water quality of tropical rainforest with water cycle were that the concentration of the BOD5, N, P in total runoff was decreased and that of the DO, pH, TDS, Mn in total runoff was increased. The virgin forest ecosystem has purifying function on the BOD5, N, and P in precipitation and make contents of the DO, pH, TDS in runoff achieve the high quality standard. So, the protection and expansion of virgin forest has produced beneficial effects on purification of water and health of inhabitants in forest.