南方水土流失严重区的生态脆弱性时空演变

Spatial and temporal changes of the ecological vulnerability in a serious soil erosion area,Southern China

生态环境脆弱性评价研究,对生态环境保护与修复具有重要意义.以福建省长汀县为研究区,选择坡度、土壤类型、多年平均降雨量、地形起伏度、归一化植被指数、人口密度、土地利用类型7个指标,通过多重共线性诊断分析,构建生态脆弱性评价指标体系,采用熵权法及综合指数法对1999、2006和2014年长汀县生态脆弱性进行定量评价,分析生态脆弱性时空分布及变化.结果表明:1999—2014年,研究区生态脆弱性等级指数总体减小,局部增大.研究区1999、2006和2014年生态脆弱性指数平均值分别为0.4533±0.1216、0.4160±0.1110和0.3916±0.1139,整体处于中等脆弱水平;生态脆弱性等级指数从1999年的2.92下降到2006年的2.38,再下降到2014年的2.13.生态脆弱性的空间格局呈内高外低的分布特征,高脆弱等级区主要分布在坡度<15°、海拔<500 m的河田镇及汀州镇一带.研究期间,生态脆弱性等级指数降幅最大的是三洲乡,最小的是汀州镇.

Research on eco-environment vulnerability assessment contributes to the ecological environmental conservation and restoration. With Changting County as the study area,this paper selected 7 indicators including slope,soil type,multi-year average precipitation,elevation deviate degree,normalized difference vegetation index,population density and land use type to build ecological vulnerability assessment system by using multicollinearity diagnostics analysis approach. The quantitative assessment of ecological vulnerability in 1999,2006 and 2014 was calculated by using entropy weight method and comprehensive index method. The changes of the temporal-spatial distribution of ecological vulnerability were also analyzed. The results showed that the ecological vulnerability level index（ EVLI） decreased overall but increased locally from 1999 to 2014. The average EVLI values in 1999,2006 and 2014 were 0.4533±0.1216,0.4160±0.1111 and 0.3916±0.1139,respectively,indicating that the ecological vulnerability in Changting County was at the moderate grade. The EVLI decreased from 2.92 in 1999 to 2.38 in 2006 and 2.13 in 2014. The spatial distribution of the ecological vulnerability was high inside but low outside. The high vulnerability areas were distributed mainly in Hetian Town and Tingzhou Town,where the slope was less than 15° and the altitude was lower than 500 m. During the study period,Sanzhou Town had the largest decreasing range of EVLI while Tingzhou Town had the lowest.