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

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.