陇中黄土丘陵区土地利用变化的生态环境响应——以定西市安定区为例

Eco-environmental responses to land use changes in a loess hilly region of Central Gansu: a case study of Anding District, Dingxi City

以陇中黄土丘陵区定西市安定区为例,开展了土地利用变化及其生态环境响应研究,为区域经济与生态环境协调发展提供理论支撑.基于1995、2005、2015年3期的Landsat遥感影像获得土地利用图,利用单一土地利用动态度、土地利用转移矩阵和生态环境质量指数等探讨了1995-2015年安定区土地利用变化及其生态环境响应.结果表明:1995-2015年,安定区除草地和未利用地外,其余地类面积皆有增长,其中草地面积减少最大,建设用地增速最快;研究期间安定区45.95%的区域生态环境质量指数保持不变,26.06%的区域生态环境质量指数有所提高,25.17%的区域生态环境质量指数轻微下降,2.59%的区域生态环境质量指数呈现中度下降,0.24%的区域显著下降;土地利用类型间的相互转化对区内生态环境质量影响显著.其中,耕地向林地、草地、水体的转化促进了生态环境质量的改善,林地、水体的转出以及耕地向建设用地的转化是生态环境恶化的主要原因.总体上,土地利用变化对生态环境起改善作用的贡献率(69.71%)要大于恶化作用的贡献率(30.29%),安定区生态环境质量有所改善.

Anding District in Dingxi was selected as a case to study land use changes and their ecological effects on a theoretical basis,so as to coordinate the development of economy and ecological environment in a loess hilly area.Based on the remote sensing images of 1995,2005 and 2015,respectively,the single land use dynamic attitude,land use transfer matrix,and ecological environment quality index were used to detect the land use changes and their ecological environment responses in Andign District from1995 to 2015.From 1995 to 2015,the area of grassland and unused land in Anding District decreased with the increase in other land use types,of which the construction land area increased apparently while the grassland area decreased quickly.The study result showed that 45.95%of the eco-environmental quality in the district remained unchanged,26.06%improved,25.17%declined slightly,2.59%declined moderately and 0.24%declined significantly.The inter-conversions of land use change had a significant impact on the eco-environmental quality.Among them,the conversions of farmland to forestland,grassland and water had promoted the improvement of eco-environmental quality.The transformation to other land uses of forestland and water area and the changes from farmland into construction land had caused the deterioration of eco-environment.In general,the ecological contribution rate of land use change to eco-environmental improvement(69.71%)was greater than the contribution rate of eco-environmental deterioration(30.29%),and the eco-environmental quality of Anding District had improved gradually during the research period.