Degradation of Soil Properties due to Erosion on Sloping Land in Southern Jiangsu Province,China

Soil erosion accelerates soil degradation. Some natural soils and cultivated soils on sloping land in southern Jiangsu Province, China were chosen to study soil degradation associated with erosion. Soil erosion intensity was investigated using the 137Cs tracer method. Soil particle-size distribution, soil organic matter (OM), total nitrogen (TN) and total phosphorus (TP) were measured, and the effects of erosion on soil physical and chemical properties were analyzed statistically using SYSTAT8.0. Results indicated that erosion intensity of cultivated soils was greater than that of the natural soils, suggesting that cultivation increased soil loss. Erosion also led to an increase of coarser soil particle proportion, especially in natural soils. In addition, silt was the primary soil particle lost due to erosion. However, in cultivated fields, coarser soil particles over time were attributed not only to soil erosion but also to mechanical eluviation as a result of farming activities. Moreover, erosion caused a decrease in soil OM, TN and TP as well as thinning of the soil layer.

SOIL EROSION AND ITS IMPACTS ON ENVIRONMENT IN YIXING TEA PLANTATION OF JIANGSU PROVINCE

Soil erosion on sloping field has led to a lot of environmental prob lems. In order to reveal the seriousness of the damage of soil erosion on slopin g fields 137Cs tracer method was used to estimate soil erosion rate. 137Cs refer ence inventory of 2200Bq/m2 in Yixing, southern Jiangsu Province, was estimated and a model for estimating erosion of cultivated soil was established in order t o avoid overestimating soil erosion rates. Then based on the soil erosion rates and measured soil physical and chemical properties, direct and indirect impacts of soil erosion on environment were further discussed. Direct impacts of erosion on environment included on-site and off-site impacts. The on-site impacts we re that soil layer became thin, soil structure was deteriorated and soil nutrien ts decreased. The off-site impacts were that water bodies were polluted. The in direct impacts of soil erosion on environment were the increase of fertilizer ap plication and energy consumption, and change of adaptability of land uses. Altho ugh erosion intensity was not serious in the study area, its environmental impac ts should not be ignored because of great soil nutrient loss and coarseness of s oil particles.

ASSESSMENT OF INDIRECT USE VALUES OF FOREST BIODIVERSITY IN YAOLUOPING NATIONAL NATURE RESERVE, ANHUI PROVINCE

Direct use values of forest ecosystem have been recognized apparently due toits easy and convenient assessment, while indirect use values are usually neglected because they arenot easy to be recognized by the public. For a nature reserve with forest ecosystem, the mostimportant economic values are the indirect use values, which provide human beings and other livingthings with beneficial services through ecological processes and functions. In this case study, aquantifying framework to estimate the annual indirect use values of forest ecosystem has beenestablished in Yaoluoping National Nature Reserve based on alternative cost method and opportunitycost method. The ecological functions assessed in the study relate to six aspects: soil protection,water conservation, CO_2 fixation, nutrient cycling, pollutant decomposition and disease and pestcontrol. These ecological functions provide an economic value of 86.1xl0~6 yuan (RMB) per year(US$10.37xl0~6), which is 25 times higher than the opportunity cost for regular timber production.This study can contribute to the monetary assessment of indirect use values of forest biodiversityand to the conservation and sustainable use of nature reserves.