CAJ | 학술논문

耕地对保障粮食安全、促进社会经济发展起着至关重要的作用。西藏生态环境脆弱，深入了解西藏耕地分布及其变化过程，可以为指导西藏农业发展、保障生态安全提供参考。本研究以4期遥感资料为数据源，采用土地利用动态度、土地利用区位指数和土地区域差异模型，对1980－2010年西藏耕地面积时空变化特征进行研究。结果表明：1）近30 a西藏耕地面积总体呈增长趋势，从3252 km2增加到3703 km2，占西藏土地总面积的比例从0.27%上升到0.31%，年变化量15.37 km2，年变化率0.46%。2）西藏耕地主要分布在日喀则、拉萨、山南、昌都4个地区，海拔>3800~4200 m之间，28°~30°N地区，其中拉萨、海拔>3800~4000 m、28°~29°N是耕地最为集中的地区。3）近30 a西藏耕地相对增加较快的是昌都地区、海拔3200 m以下和4200 m以上地区、30°~33°N地带，西藏耕地的变化表现出向高、低海拔地区、纬度较高地区扩展的趋势。近30 a西藏耕地的时空变化特征是气候等自然地理条件与人类活动综合作用的结果。
경지대보장양식안전、촉진사회경제발전기착지관중요적작용。서장생태배경취약，심입료해서장경지분포급기변화과정，가이위지도서장농업발전、보장생태안전제공삼고。본연구이4기요감자료위수거원，채용토지이용동태도、토지이용구위지수화토지구역차이모형，대1980－2010년서장경지면적시공변화특정진행연구。결과표명：1）근30 a서장경지면적총체정증장추세，종3252 km2증가도3703 km2，점서장토지총면적적비례종0.27%상승도0.31%，년변화량15.37 km2，년변화솔0.46%。2）서장경지주요분포재일객칙、랍살、산남、창도4개지구，해발>3800~4200 m지간，28°~30°N지구，기중랍살、해발>3800~4000 m、28°~29°N시경지최위집중적지구。3）근30 a서장경지상대증가교쾌적시창도지구、해발3200 m이하화4200 m이상지구、30°~33°N지대，서장경지적변화표현출향고、저해발지구、위도교고지구확전적추세。근30 a서장경지적시공변화특정시기후등자연지리조건여인류활동종합작용적결과。
Cultivated land plays a vital role in ensuring food safety and promoting social and economic development. At the same time, ecological environment in Tibet is fragile. Therefore, an in-depth understanding of the changing process of cultivated land will provide reference information for agricultural development and ecological security in Tibet. In this paper, based on remote sensing images of four periods and other related data, the temporal-spatial characteristics of cultivated land area in Tibet from 1980 to 2010 was analyzed. By using ERDAS IMAGE9.3 software, the remote sensing images were registered and geometrical corrected based on topographic maps of 1:100000 scale. According to the remote sensing image shape, texture and color, combined with land use status data, remote sensing interpreting marks were established. The supervised classification of automatic interpretation method was used to gain interpretation result, from which data of cultivated land were extracted. After correcting the interpretation cultivated land results combined with field investigation data and visual interpretation of remote sensing images, cultivated land area’s identifiable information of four periods were gotten. In order to preferably understand the temporal and spatial changes of cultivated land, the study period was evenly divided into three time periods:the first stage was 1980-1990, the second stage was 1990-2000, and the third stage was 2000-2010;and the units including administrative region, interval of altitude as well as latitude were divided. By using dynamic degree of land use, location index of land use, the temporal-spatial characteristics of cultivated land area were analyzed. Analysis of different conversion types showed that the increase of cultivated land was mainly from grassland and forest land, while the decreased cultivated land mainly was converted to grassland, forest land and construction land. From the climatic conditions, the period of 1990-2010 was beneficial to expand the cultivated land, and cultivated land in Tibet also showed a faster growth rate. The implementation of the western development strategy sped up the development of social economy in Tibet, also brought the building occupancy and ecological restoration, and therefore the cultivated land has decreased. Results showed that: 1) Between 1980 and 2010 cultivated land increased by 451 km2, from 3 252 km2 to 3 703 km2, and its proportion to the total area of the Tibet increased from 0.27%to 0.31%, with an annual change rate of 0.46%and an annual variation of 15.37 km2. 2) Cultivated land in Tibet was mainly distributed in four regions, i.e., Shigatse, Lhasa, Chamdo and Lhoka, and distributed in the altitude range of 3 200-4 200 m and the latitude range of 26°-33°N, of which, Lhasa, 3 800-4 000 m altitude and zone of 29°-30°N were the regions that cultivated land centered most. 3) Cultivated land expanded to higher altitude and lower altitude areas. Chamdo, the altitudes over 4 200 m and lower than 3 200 m and the zone of 30°-33°N increased most rapidly in area of cultivated land. It was the comprehensive effect of natural conditions and human activities, and produced the result of temporal and spatial changes characteristics of cultivated land in Tibet in recent 30 years. The special geographical environment and ecological function of Tibet had decided that in the conditions of climate warming, the impact of human activities on cultivated land must be fully understood, the consciousness of cultivated land protection should be raised; and scientific planning and reasonable use of cultivated land should be achieved so as to improve the land use efficiency and supply capacity.