西北半干旱区城郊土地利用结构与分形模型研究——以兰州市西固区为例

Study on Land-use Structure of Suburb and Fractal Model of Semiarid Area in Northwest China -A Case of Xigu District in Lanzhou City

以兰州市西固区为区域背景 ,以RS和GIS为技术手段 ,按照地貌特征将研究区划分为 4个分区 ,运用多样性指数、优势度、破碎度、分离度等指标研究半干旱区城郊土地利用结构的数量特征 ;运用分形理论建立各种土地分布形态的分形结构模型 ,以分维数为依据分析各种土地类型分布形态的复杂性与稳定性 ;探讨控制和影响土地利用格局的主要因素及土地利用优化与管理的有关问题。

Based on RS and GIS techniques the features of land-use in Xigu District of Lanzhou City are systematically and quantitatively analyzed. The main factors that control and affect the pattern of regional land-use are extracted and the fractal model of land-use fracture has been established. (1) The district is divided into four regions: river valley region, level gentle slope region, the northern mountain region and the south mountain region. River valley region, with larger index of land-use diversity, lower dominance, easily becomes the center of human activities because of its flat terrain, convenient transportation and near to the Huanghe River. The northern and the southern mountain regions have smaller index of land diversity and higher dominance limited by steep slope, relatively high altitude and far from the river. With flatter terrain, lower altitude and convenient irrigating conditions, farmland, orchard and residential site are concentrated in the level gentle slope region, where land-use diversity and dominance lie between those of the valley and the northern and south mountain regions. (2) In the terms of value of fractal dimension, the conclusions were made as follows: Water area is the most complicated and unstable land-use type. The complexity and stableness of grassland is approximate to those of water area. The complexity of scattered woodland with low stableness is under that of grassland. The complexity of farmland is higher than that of grassland whose stableness is under that of grassland. The complexity of rural residential area is higher than that of urban residential area and independent industry, but its stableness is under that of urban residential area and independent industry. (3) The main factors that affect and control the pattern of regional land-use are climate condition, landforms and human activities. To optimize and manage the land-use of this district, converting plowland to woodland or grassland and planning and managing rural residential area and independent mine industry are the two key strategies.