宁夏土地利用时、空变化及其驱动机制

The Spatio-Temporal Variations of Land Use and Their Driving Mechanisms in Ningxia,China

利用1990年和2000年两期遥感图像,通过遥感和GIS空间分析方法,研究了1990—2000年宁夏回族自治区的土地利用动态变化情况.宁夏土地利用变化最主要的特点是耕地增加,草地和未利用土地的减少,城镇居民建设用地有小规模快速增长,其它土地利用变化处于动态平衡中.空间变化表明,土地利用变化随自然和社会经济条件不同有不同程度和幅度的变化.宁夏土地利用变化的驱动机制,以反映人类活动强度和区域社会经济情况的人类活动综合度和距居民地距离因子,及自然属性方面的海拔与坡度对土地利用变化的驱动作用最显著,说明人类活动和社会经济的发达程度是宁夏土地利用变化的基本驱动力,而自然的限制因素海拔与坡度等则一定程度上限制了变化的分布.由于人口和社会经济发展的压力,宁夏在原有耕地分布基础上,新增耕地较多的位于远离灌渠、道路和居民地的地区,而且海拔和坡度均趋于不合理.

Study on regional land use/land cover change with the remote sensing and OIS method is one of the important parts of the researches of global change. Ningxia Hui Autonomous Region has a special geography location, where the physical conditions characterized by much more variety, complexity and transition. The object of this paper is to analyze the spatio-temporal change of land use in Ningxia and the driving mechanisms of the change. Using remote sensing the accurate land use data is obtained. With TM image in 1990 and 2000 in Ningxia, the actuality maps of the 1990s and the 2000s are drawn by using GIS. According to the data of the 2000s, the area percentages were 46% for grassland, 35.8% for farmland, 10.8% for unused land, 4.7 % for forest, 2.0% for residential area and 0. 9% for water area, respectively. The land use has changed by nearly 7. 8% in Ningxia from 1990 to 2000. The primary change was grassland and other land converting into farmland. Farmland area increased about 2 247 km^2 and grassland decreased about 2 375.1 km^2. Farmland had the rapidest land--use change with an annual variation rate of 0. 99%; the following was residential area （0.94 %）. During the fourteen years, agriculture, especially farmland, and city had developed greatly; much more grassland had been dug up as farmland. Special research of land-use change was done on several regions with similar physical and social --economic condition. The change in Ningxia has a remarkable regional difference. Different land types in different regions had different transformation. In Region Ⅰ3, farmland had the largest change, 1 160 km^2; Grassland in Region Ⅰ3 changed 1 257.8 km^2 ; forest in Region Ⅱ 1 changed 85.15 km^2 ; residential area in Region Ⅰ 1 changed 85.09 km^2 ; water area in Region Ⅰ 1 changed 47. 01 km^2 ; unused land in Region Ⅰ1 changed 221.27 km^2. Different land uses in different regions would bring about different physical, social and economical results. The reason causing the difference is the special physical environment and social basic. The driving Mechanisms of land--use change were analyzed by using Logistic regression. Hu- man activity is the most important driving force. The increasing farmland is dependent on the distribution of population and the social- economic base. Altitude and slope are the second important factors rather than precipitation and temperature. The people, who live in the bad physical environ- ment, where the irrigation and topographical conditions have not advantage to the planting, develop most new farmland. Land-use change in Ningxia causes resource and environmental problems. The first is unreasonable farmland structure. The largest farmland increase takes place in Region Ⅰ3, where precipitation is poor and terrain is cracked, but the grain yield of 80% of the total in Ningxia is in Region Ⅰ1. The second is degradation of grassland owing to estrepement, heavy feeding and denudation, and much grassland converts to low--level farmland, sand land and unused land. The last one is desertification when plant has been damaged, because of the arid physical condition, heavy evaporation and strong wind.