Assessment Of Forested Catchment Ecosystem Health In The Hilly And Mountain Region Of Southern Jiangsu Province, China

The paper advances the method for the assessment of catchment ecosystem health according to the land use types, the procedures of the method are: first, investigating the land use types and their areas, ascertaining the main land use type; second, decompounding the catchment ecosystem into various sub-ecosystems according to the land use types, such as forest, surface water, et al.; third, choosing suitable indices aimed at various sub-ecosystems, then assessing the health status of catchment ecosystem. Tongshan catchment in Southern Jiangsu Province of China is taken as a case study. The studied catchment ecosystem can decompounds into 2 sub-ecosystems, which is forest and surface ecosystem, and their area scale are 86.49% and 8.07%. The assessment indices of forest ecosystem health are the vigor, ecosystem services and structure, and the assessment indices of surface ecosystem are surface water quality and the ecological risk of its sediment. Based on the outdoor and indoor experiments, the properties of the indices are measured, and put forwards the model and its parameters, and the weights of indices for the assessment, the results as follows:(1) The assessment result of forest vigor is mild disease, which the Cunninghamia lanceolata is medium disease, and the other 3 forest stands are mild disease. The soil fertility for 4 forest stands are much worse, because of the absence of soil phosphorus. Besides of the Quercus acutissima, the productivity of the other 3 forest stands are under the average level of the major producing areas', and the annual increasing of DBH of Cunninghamia lanceolata, Pinus massoniana are also under the average level of the major producing areas'.(2) The assessment result of forest ecological services is sub-health, which Quercus acutissima is health, and the other 3 forest stands are sub-health. But the function of storage water for Phyllostachys pubescens is inferior, and the function of absorbing heavy metals in soil for Cunninghamia lanceolata, Pinus massoniana and Phyllostachys pubescens are under the average level of Quercus acutissima.(3) The assessment result of forest structure is mild disease, which Pinus massoniana is medium disease, and the other 3 forest stands are mild disease. The shape of forest patches are much regular, which indicates they were disturbed by artificial action more severely. The 4 forest stands are all pure forest. Besides of Quercus acutissima, the other 3 forest stands don't form compound storied forest, and their stand density is under the average level of major producing areas'.(4) The forest ecosystem in research region is mild disease, which Quercus acutissima is sub-health, and the other 3 forest stands are mild disease. The surface water ecosystem is health. Because the area scale of forest is much bigger the others', its health status has decisive affection on catchment ecosystem, so the catchment ecosystem is mild disease.(5) The advantages of catchment ecosystem are clean soil and surface water environment, bigger environmental capacity, and better forest ecological services.