Output Of Non-point Source Pollution The Different Vegetation At Phosphorus-enriched Area In Dianchi Watershed

Lake Dianchi is one of the most seriously eutrophicated plateau lakes in China. This watershed of Dianchi has been affected not only by rapid development of agriculture and urbanization, but also severely impacted by the phosphorus input from phosphorus-enriched soil erosion within the southern area of the lake. Different vegetation has different influence on phosphorus output. This study was expected to reveal the non-point pollution sources from phosphorus-enriched soil at different vegetation of Dianchi and provide scientific basis for water quality protection and non-point source pollution control. Through field investigation and experimental analysis of the samples from sample plot, some results were obtained as follows.1.Coniferous forest was the highest plant community to reduce soil suspended particles in its runoff in the Phosphorus-enriched area of southern Dianchi Watershed, The reduction rate could reach to55.45%. Huashan pine forest could highest reduce the COD and TN in its runoff up to91.03%and33.31%respectively. Yunnan pine forest could highest reduce the TP in its runoff up to65.28%;2. Water conservation of Yunnan pine forest and the Coniferous forest were the best performed plant community in Phosphorus-enriched area of southern Dianchi Watershed, The rate of reduction of runoff generation were43.28%and50.33%respectively; 3.The phosphorus lost with runoff in Phosphorus-enriched area was affected by the structure of plant community and soil nutrition characteristics. The result of plant community’s effect on non-point source pollution output suggested that:Pinaceae plants got the highest important value in Phosphorus-enriched area; In addition, the increasing structure complexity of plant community would benefit to the Phosphorus lost control.4. Woody plant played an important role in regulation of non-point source pollution in Phosphorus-enriched area, and the functional coefficient of regulation ability relatively in five different plant communities were as follows:Yunnan pine forest(5.81)> Coniferous forest(4.31)> Alnus nepalensis forest(3.75)> Eucalyptus forest(3.58)>Huashan pine forest(2.94)>Grassland(2.92).