近几十年来，随着人口的急剧增长和科学技术水平的提高，人类的活动以空前的速度、幅度和空间规模改变着陆地环境，促使土地利用/覆被格局产生了深刻变化，由此引发了一系列环境问题。塔里木河干流区地处我国干旱少雨的西部地区，人类活动的不断加剧及水土资源的无序过度开发和低效利用，使得干流区的整体生态环境十分恶劣，己成为制约绿洲生态稳定和社会经济可持续发展的主要障碍，并直接影响到我国西部开发的战略问题。本研究以塔里木河干流区为研究对象，在遥感和GIS技术的支持下，应用地理学、景观生态学、统计学、数学等学科的理论和方法，研究塔里木河干流区土地利用/覆被空间动态变化过程及景观格局的响应，揭示土地利用格局演变的机制和规律，探讨驱动土地利用变化的主要因素和驱动机制，并在此基础上，对该区土地利用/覆被变化的生态环境效应进行分析，最后提出塔里木河干流区水土资源可持续利用的对策和措施。主要研究结论如下： 1、在过去的30多年里，塔里木河干流区的土地利用/覆被发生了显著的变化，表现为耕地和居工地的大幅度扩张，并伴随着林地、草地和湿地的大面积丧失和未利用地的增加；近15年塔里木河干流区的土地利用程度不断加大，特别是2000~2005年更是明显；土地利用的变化速度经历了一个显著变化-缓慢变化-显著变化-急剧变化的U字型变化过程。在空间变化上，耕地、林地、草地和湿地的重心由下游向上中游方向移动，而居工地和未利用地的重心则由上游向中游方向移动。 2、塔里木河干流区的景观格局也发生了显著的变化，在斑块类型水平上，耕地和居工地景观比例持续增加，斑块连片分布，林地、草地和湿地的景观比例减少，破碎化程度加大，未利用地景观比例总体上增加，斑块形状简单化和破碎化；在景观水平上，景观多样性和景观均匀度增加，景观优势度降低，景观破碎度增大，优势景观类型草地和未利用地对整个景观的控制作用降低，景观破碎化程度加大。 3、塔里木河干流区海拔高度、坡度、地貌、土壤条件、水源状况和气候条件等自然因素对于土地利用/覆被格局的形成具有决定性的作用，在长时间尺度上控制着土地利用/覆被变化的方向和趋势。但在短时期内，除地貌和距河道距离对土地利用/覆被变化有一定的影响外，其他自然因素对干流区土地利用/覆被变化的影响较小。在地势较为平坦且距离河道较近的河漫滩和平原区，土地利用/覆被变化较为剧烈，而且变化首先在这些区域开始，随着可开垦土地资源的短缺，土地利用变化开始向地貌较为复杂且距离河道较远的区域发展。驱动干流区土地利用/覆被变化的主要因子是人口及经济发展因素、产业结构和政策因素及人类干扰强度，其中，人口增长和经济发展因素是塔里木河干流土地利用/覆被变化的最直接驱动力。 4、塔里木河干流区土地利用/覆被变化的生态环境效应主要表现为，①耕地和居工地等人工景观所占的比例增加，部分地区的自然景观被人工景观所取代，同时，景观多样性和破碎度逐渐增加，优势度逐渐降低，空间异质性增加，景观的边缘效应显著；②下游来水量减小，地下水位下降，水质沿程逐年恶化，同时改变了水量的年内分配，造成冬季和春季严重缺水；③土地利用/覆被变化改变了土壤的理化性质，一方面，土地的开垦和耕作降低了土壤盐分，另一方面，土地退化造成土壤容重增加，养分下降，有机质含量下降，碱性明显增强；④另外，土地利用/覆被变化引起荒漠河岸林减少，草场退化，土壤盐渍化和土地荒漠化加剧，湿地面积锐减，生物多样性降低，生态环境恶化。 5、提出塔里木河干流区水土资源可持续发展的对策与建议为：①控制人口数量，减轻环境压力；②加强水土资源调控手段和规划管理，落实土地资源可持续利用政策；③以保护策略为主，逐步恢复和重建受损的生态系统；④加强生态用地保护，建立环境友好型水土资源利用模式；⑤加强生态环境投入，切实实施生态环境保护和建设；⑥大力宣传环境保护和可持续发展，共同保护生存环境。该研究不仅可以为塔里木河干流区受损生态系统的恢复和水土资源可持续利用提供理论参考，而且对改善区域生态环境、维护社会稳定、保障国家安全、实现西部大开发宏伟战略目标具有重大的现实意义。In the last few decades, human activities have been altering the terrestrial environment by unprecedented speed, amplitude and spatial scale. The land use/cover changed profoundly, which induced a series of environmental problems. The main stream of Tarim River is located in the arid inland with the rare rainfall in the western area of China, where extremely fragile ecological environment resulted from the increasing human activities and the excessive disorder development and ineffective utilization of the soil and water resources. The abominable eco-environment has been a barrier to keep the oasis ecosystem stable and the local socio-economic developments sustainable, and directly affects the strategies of great exploitation in western China. Taking the main stream of Tarim River as research object, through remote sensing and GIS technology, based on the theories and methods of geography, landscape ecology, statistics and mathematics, the temporal and spatial changes of land use/cover and response of landscape pattern were analyzed, and the mechanism and laws of the evolution of land-use pattern were revealed in this paper. Driving forces and mechanisms that lead to changing of land use/cover pattern was also analyzed. Through above analysis, the eco-environmental effects of LUCC in study area were appraised synthetically. At last, this paper provides some measures and suggestions on water and soil resources development and utilization. The main conclusions are as summarized as: Firstly, there had been a great change of land use/cover in the main stream of Tarim River during the past 30 years. The areas of farmland and residential land increased obviously, areas of grassland, forest and wetland decreased, and that of unused land increased first then decreased. The major patterns of land use change were the conversions of grassland, forest and wetland to farmland, farmland to residential land, and grassland to unused land. The integrated index of land use increased continuously during the past fifteen years, especially from 2000 to 2005. Land use change rate underwent a process of ‘U’ shape with ‘obvious change - slow change - obvious change - tremendous change’. As to the spatial distribution, the centroids of farmland, forest, grassland and wetland had a migration tendency from downstream to upstream and middle stream, meanwhile, the centroid of residential land and unused land had a tendency from upstream to middle stream migration. Secondly, the landscape pattern had also greatly changed during the past 30 years in the main stream of Tarim River. At class level, the percentage of landscape of farmland and residential land increased continuously with the characteristics of concentrated distribution, meanwhile, the percentage of landscape of forest, grassland and wetland had reduced with a fragmentation trend, and the percentage of landscape of unused land had increased as a whole with a fragmentation and simple trend. At landscape level, landscape diversity index increased while landscape dominance index decreased. Simultaneously, landscape fragmentation index increased gradually. The control function of grassland and unused land to landscape declined, and the diversification and evenness of landscape pattern were more obvious. Thirdly, the natural factors, such as, altitude, slope, geomorphology, soil conditions, water conditions and climatic conditions, play a decisive role and control directions and trends of land use/cover change in the long time scale. However, in a short period of time, in addition to topography and distance from the river which had some influences on land use/cover change, other natural factors had less effect on land use/cover change in the main stream of the Tarim River. In relatively flat floodplain and plain where close to the river, land use/cover changed firstly and more rapidly. As the shortage of cultivated land resources, land use/cover change occurred at the areas with more complex topography and farther distance from the river. Driving factors of land use/cover change are population growth and economic development, the industrial structure and policy, and human disturbance intensity, in which population growth and economic development are most direct driving force in the main stream of Tarim River Fourthly, the main eco-environmental effects by land use/cover change in the mainstream of Tarim River were as following: 1) the percentage of the artificial landscape such as farmland and residential land increased, and some areas of the natural landscape had been replaced by artificial landscape. At the same time, landscape diversity, fragmentation and spatial heterogeneity increased while landscape dominance decreased gradually, and landscape edge effect was more significant. 2) Caused the decrease of water resources in downstream, decline of water table, deterioration of water quality along the way in year-on-year, but also changed the distribution of water during the year, resulting in severe shortage in winter and spring. 3)land use/cover change had transformed the soil physicochemical properties. On the one hand, land reclamation and farming reduced soil salinity; on the other hand, land degradation caused increase of soil bulk density, decline of nutrient and organic matter content and significant enhancement of alkaline. 4) Caused the reduction of riparian forest, grassland degradation, soil salinization, land desertification, wetlands area reduction, biodiversity decrease, and ecological deterioration of the environment. At last, measures and suggestions are put forward as following: 1)control population quantity to reduce the pressure on the environment; 2) strengthen the regulation and planning management of land and water resources and implement the policy of sustainable utilization of land resources; 3)recover and reconstruct damaged systems through protective measures; 4)strengthen ecological land protection, and set up a mode with environment-friendly utilization of water and land resources; 5)strengthen ecological environment inputs, and implement ecological environment protection and construction effectively; 6) vigorously promote environmental protection and sustainable development to protect environment jointly. The study not only can provide theoretical basis for restoring damaged systems and achieving sustainable development of the regional in the main stream of Tarim River, but also have profound significance of theory and practice to improve the regional ecological environment, safeguarding social stability, protect national security, and implement West China Development Drive
