石羊河流域植被生态系统生态风险评价研究

区域生态风险评价涉及到多风险因子、多风险受体、多评价终点,强调不确定因素以及空间异质性的特点.以石羊河流域植被生态系统为例,以区域生态系统类型为着手点,计算不同生态系统类型的生态指数、脆弱度和生态损失度,根据不同种类和级别生态风险源的综合风险权重,利用ArcGIS 9.3软件进行叠加分析,形成不同的生态风险区.结果表明,石羊河流域植被生态风险空间差异性较为明显,其中1级风险区主要分布在石羊河流域上游,占全区面积的3.87％,以肃南和天祝2个县最为集中,植被类型多为有林地；2级生态风险区分布多与1级风险区相连,占全区面积的4.38％,植被类型多为灌木林；3级和低风险区主要分布在下游和中游地区,植被类型为草地和耕地.对石羊河开发利用时应当避免在1级和2级风险区进行大规模的土地开发利用,在3级和低风险区进行土地利用时应注意对土地进行保护利用.

Research on Ecological Risk Assessment of Vegetation Ecosystem in Shiyang River Basin

Regional ecological risk assessment is characterized by multiple risk stressors,receptors and endpoints with uncertain factors and spatial heterogeneity.By taking the vegetation ecosystem of the ShiyangRiver basin in Gansu Province for an example,the ecological indices of fragility degree,ecological loss andrisk source level of different vegetation ecosystems are analyzed for different risk patches by overlaying analysis with the aid of ArcGIS 9.3.Results show that the spatial variability of vegetation ecological risk in theShiyang River basin is more obvious.The first level risk area,accounting for 3.87% of the total area,ismainly located in the upper reaches of the Shiyang River basin,with Sunan and Tianzhu Counties being mostconcentrated and vegetation type being mostly woodland.The second level risk area,accounting for 4.38%of the total area,is connected with the first level risk area and vegetation type is mostly shrubbery.The thirdlevel and low level risk areas are mainly located in the downstream and midstream and vegetation types aregrassland and farmland.Finally,the large-scale land development and utilization of Shiyang River basinshould be avoided in the first and second level risk areas,and land use in the third level and low level risk areas should be protected.