陕西黄土台塬区土地生态风险时空差异性评价

Assessment on Spatiotemporal Ecological Risk in Loess Highland Region of Shaanxi Province

基于RS和GIS支持,采用土地转移流和土地生态风险强度指数,对陕西黄土台塬区的土地利用变化动态及其结构性风险进行了评价。结果表明:(1)1990—2010年陕西各台塬区的建设用地均有所增长、耕地除宝鸡台塬区和西安台塬区增长外,其他台塬区均减少,生态用地则刚性减少。(2)研究时段内土地利用的生态风险指数表现出"高—低—高"的发展过程,1995年是一个拐点。(3)市域尺度上,宝鸡台塬区和西安台塬区土地利用的结构性风险自1995年以来有较大幅度的攀升,2005年后临近"高等"生态风险。(4)县域尺度上,除了白水县和永寿县的生态风险降低外,其他区县均有所增大,各区县生态风险的差异性也进一步扩大。1990年、2000年、2010年土地结构风险的变异系数分别为10.43%,10.57%,10.79%。

Based on RS and GIS,this paper used the index of land transfer flow and land ecological risk to analyze the land use change dynamic and to assess land structure ecological risk during 1990—2010.The results are as the follows.The built-up land enlarged in each loess highland region at city scale,the cultivated land reduced except in loess highland region of Baoji and loess highland region of Xi′an.Land use ecological risk index presented the pattern of‘high—low—high'during the study period,and the year of 1995 was the turning point.At city scale,loess highland region of Baoji and loess highland region of Xi′an enlarged very much since 1995,the value was up to‘high'ecological risk grade since 2005.At county scale,the ecological risk grew except Baishui County and Yongshou County,and the difference among the counties enlarged during 1990—2010.The variation coefficients of land structure risk were 10.43%,10.57% and 10.79% at1990,2000 and 2010,respectively.