鄂尔多斯市土地利用生态安全格局构建

Building ecological security pattern based on land use:a case study of Ordos, Northern China

合理构建区域土地利用生态安全格局来实施管理对策和改善区域生态安全水平,已经成为区域生态环境保护的新需求。以位于中国北方农牧交错区的鄂尔多斯市为研究区,基于自然地理数据、社会经济统计数据、土地利用/覆被数据等,借助多目标优化模型和GIS空间分析技术,构建了鄂尔多斯市土地利用生态安全格局,结果表明:(1)不适宜性耕地所占比重较大,林地和草地分布比较合理,适宜的未利用地面积所占比重较大,后备土地资源丰富;(2)多目标优化结果显示,耕地、林地、水域和建设用地面积呈现增加的趋势;草地面积基本保持不变;未利用地面积大幅度下降;(3)土地利用生态安全格局显示,耕地面积增加,主要分布在水分条件较好的河流、湖泊和水库等的周边地区以及城镇和乡村居民点周围;林地面积大幅度增加,主要分布在达拉特旗北部和准格尔旗东部;草地略有增加,广泛分布于库布齐沙漠和毛乌素沙地以外的地区;建设用地增加面积主要来自于重点发展城镇的扩展和规划的重点矿产资源开采区;未利用地大幅度减少,主要集中在杭锦旗境内的库布齐沙漠以及乌审旗和鄂托克旗境内的毛乌素沙地。研究结果对鄂尔多斯市土地资源管理和生态安全建设具有重要指导意义。

To improve ecological security level, reasonably building regional ecological security pattern based on land use has been the requirement for eco-environmental protection. Ordos, a typical farming-grazing transitional region in the northern part of China and also an ecological vulnerable and sensitive area, confronts a sharp conflict between its vulnerable ecological environment and its social and economic development. Taking Ordos as the study area and using physical geography data, socio-economic statistical data and land use/cover data, this paper built ecological security pattern based on land ecological suitability assessment with the multi-objective optimization model and spatial analysis technology. First, slope, soil type, gein, water resources and soil erosiveness are chosen as diagnostic indices for evaluation criterion. The method of lowest restrict factor is used to assess the land eco-suitability for three kinds of land use types, which are cultivated land, woodland and grassland. The results are presented as follows ： unsuitable cultivated land accounts for a large proportion. The distribution of woodland and grassland are relatively reasonable. The proportion of the area of appropriate unused land is relatively large, which acts as the important potential land resources. Secondly, the results derived from the multi-objective optimization with two objective functions： ecological security and economic security, and some constrains such as land resources quantity and the demand for it, the water resource and soil erosion. It suggested that compared with the land use in 2008, the area of cultivated land, woodland, water, construction land showed an increasing trend, the area of grassland changed little, while the unused area decreased significantly in 2015. Thirdly, based on the multi-objective optimization, land ecological suitability assessment, land ecological security evaluation results and the city and mineral resources general plan, the ecological security pattern is built following the land use type adjustment principles under both ecological security and economic security scenarios. The adjustment results of cultivated land, ecological land （woodland and grassland ） and natural reserve （unused land） under ecological security scenario showed that the cultivated land expands, mainly distributing along the rivers, lakes and reservoirs where the water conditions are favorable and at the peripheries of towns and villages. Woodland, whose area increased significantly, is mainly distributed in the northern part of Dalad Banner and the eastern part of Jungar Banner. The grassland, the dominant land-cover type, increases slightly, and it covers almost the whole study area except Kubuqi Desert and Mu Us Sandland （sparsely distributed among the two deserts）. Unused land lessens in large amounts, and it is mainly distributed in Kubuqi Desert located in I-Ianggin Banner and Mu Us Sandland situated in Uxin Banner and Otog Banner. The adjustment results of construction land and mining area under economic security scenario mainly reflected in the increase in construction land which mainly derives from the expansion of key developing towns and the expansion of encouraging mining areas, Taking both the quantity optimization and spatial configuration into account makes the results more close to reality and bears great implications to land resources management and ecological security improvement. All findings would be useful for the researchers and local authorities, allowing it to be used as a reference for the study of land use planning or supporting land resources management.