| Danjiangkou Reservoir is the water source area of the“South-to-North Water Transfer”mid-line project,having important strategic significance.Citrus planting is the main income for farmers in the Danjiangkou reservoir area.During the production process,a large amount of fertilizer is applied.According to the analysis report,the Shiyan area where Danjiangkou is located roughly uses about 1.0×10~6t of fertilizer per year,and the utilization rate is very low,about 30%?40%,which causes the agricultural non-point source pollution of the water source area to become increasingly serious.This experiment was carried out in Longkou Forest Farm in Danjiangkou Reservoir Area.The waterfront vegetation buffer belts of five typical forest types(Pinus massoniana,Quercus sinensis,Pinus massoniana mixed forest,fresh bamboo forest and wild grassland)were selected as the study.The object,using community survey,soil physical and chemical properties analysis of different width waterfront vegetation buffer belts,simulated surface runoff test,etc.,studied the community characteristics of the waterfront vegetation buffer zone in Danjiangkou reservoir area,the distribution characteristics of non-point source pollutants in the reservoir area and waterfront.The interception effect of the type and width of the vegetation buffer zone on surface runoff pollutants.The waterfront vegetation buffer zone acts as the last barrier to the surface runoff into the reservoir area,and its interception effect on surface source pollution is of great significance.Limited by the conditions of land resources and geography,it is impossible for the waterfront vegetation buffer zone to randomly select the vegetation type and expand the width unrestricted to increase its non-point source pollution interception effect.Therefore,it is of great significance to study how to create a more scientific and economical waterfront vegetation buffer zone.research shows:(1)Five kinds of buffer zone plant communities belong to 52 families,48 genera and 52families,with more than 3%of the genus,10%of the genus,and 87%of the genus.The herbaceous layer in each type of tree buffer zone is the highest species richness in the community,but the degree,frequency and coverage are very low.The top 3 herbaceous plants in the wild grassland are Bermudagrass,Pleurotus ostreatus and Dendrobium,and the dominant species is Bermudagrass with a coverage of 35.24%.(2)The distribution characteristics of non-point source pollutants in the waterfront vegetation buffer zone of five different forest types are characterized by the greater the width(ie,the farther away from the citrus orchard),the lower the non-point source pollutant content,indicating that along with the waterfront vegetation The increase of the buffer zone width,the greater the proportion of non-point source pollutants being trapped,the source pollutant content of 10?-20cm soil layer is less than 0?10cm.(3)Simulating surface runoff experiments.Above the ability to intercept surface source pollutants,III is the best type of forest in the range of 15?18°,and II is the worst type of forest.To achieve an 80%rejection rate,the width of the waterfront vegetation buffer zone should be20.4?70.2m.In the range of 11?21°,the smaller the slope,the better the interception effect. |
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