Environmental Impacts on Wetland Soil Characteristics in Jianhu Nature Reserve,West Yunnan Province

The soil characteristics and human disturbances on wetland soil of Jianhu Nature Reserve were analyzed.The results showed that the water body area and water storage capacity of the wetland reduced by 33.34% and 62.95% respectively within the past 50 years by reclamation and disafforestation in the catchments.Organic matter and total nitrogen of the soil lost by 43.03% and 60.71% individually since the wetland has been turned into ordinary cropland,while these two indexes dropped by 6.4% and 21.43% respectively since the swamp land has been changed into paddy field.Because of the intake of soil nutrients,the total nitrogen and total phosphorous contents of the inflow water by lakeside were increased to 3 to 10 times that of the water in the center of the lake,whereas the contents of NH₄⁺,NO₂^-and NO₃^- were increased to 4 times,and the suspended substance(BOD,COD) was doubled in the water by lakeside,which made the water adjacent to the lakeside turbid.The ecological environment deterioration tendency of Jianhu Nature Reserve wetland and its nearby regions was studied,and some tactics and measures to contain this tendency and for sustainable utilization of the land resource in the area were put forward.