Research On Ecosystem Health Assessment In Guangxi DaHuanjiang Basin

The growing problem of basin ecosystem health is a critical issue solved byhuman society. The Guangxi Dahuanjiang basin belongs to fragile ecological systemunder the constraints of Karst geological background, the problem of ecologicalenvironment is prominent, have the representative of the research. Study the basincomprehensive ecosystem health status, which will provide a scientific basis for basinecological management and restoration of basin, achieve the sustainable developmentof basin.Taking the Dahuanjiang Basin as study object, selects natural conditions limitingfactor-health instruction factor-the impact of human activity factor evaluationmodel,and adapting RS and GIS teleology, this Paper established a evaluation systemwhich contain13evaluation index(Net primary productivity, Vegetation coverage,Soil erosion sensitivity index, Landscape diversity, Landscape evenness, Landscapefragmentation, ecological elasticity, Water density, The value of ecosystem services,population density, human disturbance index, The per capita net income of farmers,more than25°farmland index). The unit of assessment is small watershed. Then, thepaper obtained the ecosystem heath as assessment results of Guangxi DahuanjiangBasin in2011by Using the spatial principal component analysis method, and furtheranalyzed the ecological health factors of this basin, and ecosystem health of thetypical small watershed were compared, revealing spatial distribution rule ofecosystem health of Guangxi Dahuanjiang basin. The results indicate follows:1. Ecosystem health scores range between2.52to15.76in Guangxi Dahuanjiangbasin. Among them, the excellent health district area reached21065.94hm2,accounting for9.94%of the whole basin, is mainly distributed in the northeast andnorthwest areas of the basin. Better health district area is82087.11hm2, accountingfor38.74%of the whole area, is mainly distributed in southern basin area innorth-central and outlet. Middle health district is mainly located in the western and eastern sides of the basin, which is an area of48966.84hm2, accounting for23.11%the entire watershed. Worse health district has an area of45288.27hm2, accountingfor21.37%of the entire basin, is mainly located in the south-central basin. Thedistrict of extremely bad health is mainly located in Downstream of Dahuanjiang rivercoast, which is an area of14486.04hm2, accounting for6.84%the entire watershed.2. From upstream to downstream, ecosystem health score from high to low.Because the upper basin is soil and water conservation district and covered with virginforest. The basin upstream of natural resources conditions is good with a strongdegree of system flexibility and anti-jamming. As the basin upstream of the highaltitude mountain of the topography, not adapt to large-scale utilization for human, soless affected by human activities, the upstream ecosystem health is better. Western andeastern edges of the basin is a typical karst area which is surface fragmented. Humanexcessively dug up the waste land lead to serious soil erosion and bedrock bare,eventually appeared rocky desertification. In recent years, the project of rockydesertification control was carried out by government. This project includes closehillsides to facilitate afforestation, reforestation, planting grass and other measures.Eco-environmental quality of the area has improved, so the ecological health of thegeneral. The region of midstream and downstream basin relative flat terrain, withabundant water resources, suitable for planting fruit trees and forest, is an importantagricultural region and resettlement areas, so densely populated. Excessivereclamation resulted in low vegetation coverage, a small degree of system flexibility,ecosystem health is poor. Especially the downstream of Dahuanjiang, was moreserious disturbed by human and the surface is covered with farmland and building.Overwhelmed by the upstream beneficiation wastes, the coastal downstream farmlandhas high heavy metal content in soil, the low value of ecosystem services lead toecosystem health is poor.3. By typical small watershed ecosystem health comparative results shows healthstatus of the29th,21th,10th,2th,6th small watersheds from excellent to poor. As thesmall watershed of the29th,21th higher elevations, less affected by the influence ofhuman activities, good natural conditions, ecosystem health than other small watershed. While the2th and the6th small watershed low altitude, high populationdensity, seriously affected by human disturbance, the small degree of systemflexibility. The10th small watershed is a typical karst region，due to the innateendowment is poor and excessive reclamation steep resulting in rocky phenomenonprominent. After artificially governance, the quality of environmental has improved.Studies show that combining ecological characteristics and socio-economicconditions of the study area, the establishment of the index system for the study area,using appropriate research methods, based on remote sensing and geographicinformation system technology evaluation Basin ecosystem health status is feasibleand capable of better performance spatial differences in ecological characteristics ofwatershed health.