西北干旱区城市土地利用变化及其区域生态环境效应——以甘肃河西地区为例

THE URBAN LAND USE TRANSFORMATIONS AND ASSOCIATED EFFECTS ON ECO-ENVIRONMENT IN NORTHWEST CHINA ARID REGION:A CASE STUDY IN HEXI REGION,GANSU PROVINCE

基于高分辨率土地利用 /土地覆盖数据 ,本文对 1 985～ 2 0 0 0年期间河西地区城市土地利用变化的区域生态环境效应进行了定量分析 ,结果表明 :1 ) 1 985～ 2 0 0 0年期间河西地区总体生态环境质量在一定程度上维持着相对稳定 ,但生态环境质量改善和恶化的两种趋势并存 ,并在县级行政单元上表现出明显的区域分异特征 ,城市用地变化对区域生态环境的影响总体而言不显著 ;2 )整个河西地区城市用地增长缓慢 ,表明其城市化进程缓慢。与城市用地变化有关的土地利用类型也多分布在金昌、嘉峪关、张掖、武威和酒泉 5个地级市所在地区 ,表明这些区域的城市化过程相对活跃 ;3)城市用地变化对生态环境影响的空间规律表现为 :使生态环境原本较差的地区生态环境质量有所增加 ,而使生态环境质量较好的地区生态环境质量降低 ;4)城镇用地与工矿用地对区域生态环境的影响表现出与城市用地总体基本一致的规律 ,但农村居民点则对生态环境正、负两方面影响都较为显著 ;5 )城市用地扩展对区域生态环境的影响也体现出与城市用地总体类似的区域分异特征 ;而城市用地收缩的影响则与此趋势相反。

Based on the data of land use/land cover in Hexi region, Gansu Province, the process of land use transformation and associated contribution to the regional eco-environment in Hexi region were measured and quantified spatial-explicitly, the main results and findings include that: 1) the general quality of regional eco-environment has maintained relative stabilization in the past 15 years. However, the trends of both improvement and degradation in eco-environment were coexist, and displayed their spatial heterogeneity in county-level; 2) the transformation among grassland, woodland and cultivated land acted as the key contributors to the changes in regional eco-environment, while the contribution from the urban land use transformations were insignificant in general; 3) the growth of urban land use was rather slow, indicating that the process of urbanization was generally in active in Hexi region. The urban land use transformation occurred more frequently in Jinchang, Jiayuguan, Zhangye and Wuwei, showing the more active process of urbanization in those region; 4) in county level, the impacts of urban land use transformation on the regional eco-environment exhibited the following regional heterogeneity, i.e., the urban land use transformation improved the eco-environment quality where the quality of eco-environment is inferior originally, and reduced the quality of eco-environment in the area with high quality in eco-environment formerly; 5) among those urban land use transformation, the impact of city and industry land use transformation on eco-environmental quality presented the same trends as that of general urban land use, while the transformation associated with township residential land use exhibited the strong impacts on regional eco-environment both positively and adversely; 6) the growing and shrinking of urban land use both show the two-edged effects (i.e., positive and negative) on regional eco-environment in Hexi Region, the growing of urban land use showed similar trends as the general urban land use in its effects on regional eco-environment, while the shirking of urban land use behaved adversely, i.e., they may continuously undermine the eco-environment where the eco-environmental quality is formerly inferior, and enhance the eco-environment where the eco-environmental quality is high originally.