Assessment of Water Conservation Function of Forest Ecosystem in Taihe County,Jiangxi Province

Water conservation is an important function of forest ecosystem,which could weaken rainfall erosivity,slow down surface runoff and preserve soil and water.It is a comprehensive effect of three main hydrological processes,namely canopy interception,litter containment,and soil water storage.On the basis of the sixth inventory data of forest resources(2003) in Taihe County,Jiangxi Province and literature reviews,this paper estimated the function of water conservation and its spatial distributions and variations.Also,we compared the water conservation capacity of forest ecosystem through three layers by forest types,age groups,elevations and slopes.The results showed that,the canopy layer could intercept approximately 16.31% of rainfall;the litter layer could hold 2.14% of water and the soil layer could store 81.55% of water.It can be seen that that soil layer is the main aquifer of forest ecosystem.The total amount of rainfall interception and water holding was 141 million cubic meters in Taihe.The amount of water conserved by different vegetation types in a descending order was Cunninghamia lanceolata forest Pinus massoniana forest Pinus elliottii forest Broad-leaved forest Phyllostachys pubescen forest Shrubby forest Mixed forest Economic forest.The contribution rate of water conservation of young stand,middle-aged stand,near-mature stand,mature stand and over-mature stand forests was 17.58%,65.39%,14.18%,2.48% and 0.37%,respectively.The capacity of water containment increased with the increasing age of forest.The spatial distribution of water conservation capacity of forest ecosystem in Taihe tended to decrease from eastern and western to the central part.The damage of forest vegetation or soil could lead to water loss and soil erosion,and even natural disasters.Therefore,reasonable management of forest ecosystem under different conditions would play an essential role in the enhancement of water conservation function.