Water Conservation Function Of Typical Forest Types And Their Impacts On Water Quality In Song Hua Ba Water Source Area

Sources of water have become one of the most prominent problems in many countries and regions, especially in many large cities under today's ecological environment crisis. As it is known, the rapid construction of water conservation forests and continuously increasing their conservation function will play very important role in solving this problem.Because of many problems existing in water source protection district of Song Hua Ba in Kunming, Yunnan Province, such as continuously weakening of the function of water conservation forests, tree species configuration, stand structure adjustment and space layout in the process of construction of water conservation forests, water conservation function of typical forest types and their impacts on water quality in this area were deeply studied by the method of system theory in order to supply theoretical and technical support for the construction of water conservation forest and water quality improvement in the future. The results showed:1. The water conservation function of different forest stands directly depended on the structure characteristics and their interactions among the canopy layer, the litter layer and the soil layer. Therefore, adjustment of the forest structure and their relationship among above-ground, soil surface and soil layer was a fundamental way to improve the water conservation function. Our study on eight different forest stands in the water source area of Song Hua Ba indicated that the holding water capacity of Christmas stand was the best, about 53.59%, and shrub forest floor was the least, about 31.62%. Broad-leaved forest and coniferous and broad-leaved mixed forest, such as Christmas tree forest, Alnus-Yunnan pine forest, Alnus-Mountain pine forest and shrub-Alnus forest have the most strongest integrated function of storage rainfall, meanwhile coniferous forest, such as Yunnanensis-Keteleeria forest, have stronger integrated function of storage rainfall, and shrubs have weakest integrated function of storage rainfall.2. The monitoring results of water quality of surface runoff indicated different forest stands could improve water quality of surface runoff, in particular, for those stands with stronger holding water capacity. The monitoring results of water quality of groundwater showed that different forest stands could purify water quality of groundwater, water quality was better in those sampling locations with higher forest cover rate. For the pollutant decrement of total phosphorus, total nitrogen and NH3-N, Christmas forest stand was highest,25%,17% and 32%, respectively.3. Through the study on influence of water resources conservation forest on the surface runoff and groundwater, the results indicated that there was definite positive relationship between forest stands, forest structure, and water quality; meanwhile this relationship could be also affected by human disturbance. Because shrubs were surrounded by some cultivated lands, their water quality was the worst, classified as V class.