北京市耕地多目标适宜性评价及空间布局研究

A Suitability Evaluation of Cultivated Land in Beijing for Multi-Purposes Use and Its Spatio-Temporal Investigation

从土地具有多宜性和耕地具有多功能性的角度出发,构建了耕地自然适宜性评价指标体系、经济适宜性评价指标体系和生态适宜性评价指标体系,基于北京市自然、社会、经济资料及图形资料,运用GIS地理空间分析功能,通过对评价要素的空间叠加、计算,评价了北京市耕地不同利用目标下的适宜性级别和面积,结合不同的发展阶段耕地承担的不同功能,对耕地的多目标利用类型做了分析。结果表明:耕地自然适宜性高、中、低的面积分别为1207.65km2、920.16km2、193.99km2;耕地经济适宜性高、中、低的面积分别为:1077.86km2、1002.55km2、241.39km2;耕地生态适宜性高、中、低的面积分别为1170.46km2、1044.25km2、107.09km2。为了体现耕地多目标适宜的弹性空间,设计了经济效益型、社会效益型、生态效益型3种方案,并对不同的发展目标下的投入水平做了探讨,评价结果可为城市新增建设用地的时空配置提供参考。

Methods for suitability evaluation of cultivated land for multi-purposes use and spatio-temporal distribution were investigated in this paper based on current natural, social and economic situations as well as associated maps of Beijing. With the spatial analysis methods and software packages of GIS, natural suitability evaluation, economic suitability evaluation and ecological suitability evaluation of cultivated land in Beijing were performed in succession. Suitability ranks and areas were estimated by means of spatial overlapping evaluation factors. With distinct development stages, functions of cultivated land vary considerably. Moreover, the authors examined the types of cultivated land for multi-purposes use. Results showed that the areas of cultivated land could be generally categorized to three levels： high suitability, moderate suitability and low suitability. It was estimated that the natural suitability with high, moderate, and low levels accounted for 1207.65km2, 920.16km2 and 193.99km2, respectively. The areas of cultivated land economic suitability with high, moderate, and low levels were found to be 1077.86km2, 1002.55km2 and 241.39km2, respectively. Meanwhile, the areas of cultivated land ecological suitability with high, moderate and low levels accounted for 1170.46km2, 1044.25km2 and 107.09km2, respectively. In order to involve the multi-purposes suitability into elastic spatial planning and take into account the functions of cultivated land about production, ecological and social security, three utilization schemes were worked out for different development levels. They are economic benefit-type, social benefit-type, and ecological benefit-type. It was noted that the schemes are interrelated with different developing levels. With different land use types investments in cultivated land can be different, approaching the investment subject from different ways. At an early stage of economic development, the farmer usually has limited means to earn money, primarily depending on cultivated land and taking it to be a major source of incomes. To this end, the food value of cultivated land is superior to any other value of land to meet the need for food for a family. This causes the cultivated land to give full play to the benefit of production. Farmers＇ incomes increase with the rapid development of industries, with cultivated land maintaining the balance between food demands and making money at the stage, in which they are keen on seeking both the food security and profits. However, conflicts frequently arise from agricultural production manages. The anticipated profits are instable at this stage. This requires the cultivated land to give full play to ensure social capacity. With population growth, Beijing is becoming more and more restrained by water shortages and land resources deficiency. Taking cultivated land as green space would greatly helpful in cultivated land for multi-purposes use. Adequate utilization of agricultural landscape with its ecological functions would also be a promising way to make the city more comfortable for living. These results and suggestions can provide meaningful information and reference for land use planning in Beijing.