中国西部干旱区生态环境演变与调控研究进展与展望

国家重点基础研究发展规划项目"中国西部干旱区生态环境演变与调控研究"实施 2年来,在古气候重建和环境变化,绿洲的演变规律与驱动力,绿洲水盐平衡与主要水文过程,绿洲生态系统的结构、生态过程与稳定性,山地、绿洲、荒漠三大生态系统耦合机理,生态景观演变规律及其对气候变化的响应,重大工程行为的生态环境效应,荒漠化成因及时空分布等研究方向和内容上取得了重要进展。在此基础上,项目后 2年的研究重点将继续以绿洲安全机制研究为核心,在时间序列上,重点研究近 2 000年来绿洲的形成演变规律,特别是近百年及近50年来西部干旱区气候变化与绿洲形成演变的关系,定量辨识绿洲发展演化的驱动力;在空间结构上,阐明绿洲格局的动态过程,深入探明山地、绿洲及荒漠生态系统耦合关系、绿洲生态系统稳定性机理与安全、高效、持续发展模式等;结合西部大开发工程建设和产业发展的进程,研究开发重大工程的生态环境效应,建立不同类型的生态建设示范区;配合国家重大工程时段,对西部干旱区生态环境演变趋势进行预测,提出生态系统的调控体系和管理模式,为西部开发和可持续发展服务。

THE RESEARCH ON ECO-ENVIRONMENTAL EVOLUTION, CONTROL AND ADJUSTMENT FOR THE ARID LAND IN WESTERN CHINA:RESEARCH PROGRESS AND PROSPECT

    The National Key Project of Basic Research: The Research on Eco-environmental Evolution, Control and Adjustment for the Arid Land in Western China has been undergone for two years. Some research progresses have been made in everyimportant study field of the project. First, by the analysis of growth ring, lake drill core sample and loess records the high scale of century climate evolution model for arid land has been build, and at the same time climate saltation affairs since Holocene have been analyzed. The research shows that the climate of Last Ice Age is highly unstable in arid land, and this instability of climate isglobal significance. The evolution and development of oasis in arid land are influenced by tectonic movement, climatic oscillation and human disturbance. Humandisturbance is always rapid. According to the results from environmental changestudy of arid land, human disturbance is the dominant factor on the oasis evolution in the decade scale, but climatic oscillation is outstanding in the centuryscale, tectonic movement is obvious in the millennial scale. All facts show that the process of human disturbance is strong. Based on the understanding of influences of climatic oscillation and tectonic movement on the oasis evolution, sustainable development of oasis can be realized by scientifically and rationally aggrandizing the process of human disturbance. In addition, the evolution and development of typical ancient oasis in arid land has been investigated and it provides a foundation for revealing the spatial and temporal dynamics of oasis evolution.
    The oasis stability is the core research content of this project. By the two-year research, some conclusions are as follows. The second salinization inside the oasis and desertification outside are two important factors influencing the stability of oasis in arid land. First, in arid land the inland basin is the unit of salt and water distribution, much irrigation field has been threatened by second land salinization. The spatial and temporal dynamics of water and salt concentration has been investigated, and then it provides a foundation for rational utilization of water resource in whole basin to protect the second salinizaition.Second, by the investigation and theoretical analysis on relationship of local climate and plant physiological ecology the theory of ecotone adjustment has been advanced. Then, in regional scale the relationship of climate and ecosystem dynamic has been analyzed, and it is shown that there is obvious feedback between climate and ecosystem.
    In arid land, mountain, oasis and desert are subsystems coupling one another. Water, soil, heat and all other resources are balance in these subsystems; to protect the balance of these resources is to protect the stability of these three subsystems. 
    We have analyzed the ecological effect of important engineering project and water and land exploitation in arid land; we selected some important and typical project to investigate, such as desert road, speedway, and water derivation, etc. Through investigation to analyze the ecological effect of project on its surroundings and to put forward the measure of ecological rehabilitation. Taking the Tarim Basin as the case study to analyze the formation and spatial and temporal distribution of desertification. By analysis we built the model of desertificationdevelopment according to the soil evolution process. It is also shown that the land desertification is a gradual change process in whole, but in some scale and some moment, desertification puts up break character. For different ecosystems,their evolution processes are also different, and their reversible part of evolution has different size because of the difference of break boundary. By building the break model of desertification, we can prove up the discipline of gradual change and break during the desertification process, and decide the critical boundary of break and their combination variable. By all these we can seek the cut-in spot of adjustment, control and prevention of desertification. Moreover, thedesertification evaluation map has been finished and the desertification evaluation index has been built.
    The principle, methods and scheme of ecological division in arid land have beenfinished. The pattern and dynamics of landscape in arid land have been analyzed according to satellite data, at the same time the influence of front range of Tianshan Mountain on hydro-process of plain range, oasis ecosystem development, climate and vegetation has been analyzed. Using the GCM model to simulate the evolution of ecosystem in arid land under the background of global climate change.By the analysis of ecological environment evolution and development in arid land, the ecological environment information database and decision support system have been designed. According to the research of the ecological environment adjustment and management method, the measure and approach of adjustment and management have been brought forward.
    Beyond these progresses,we will continue to keep the oasis safety mechanism asour research core. At time serial, we will emphasize the rule and power driving the oasis to develop in recent 2000 years,especially the relationship between the climate changes of the western arid land and the oasis development in recent 100 years and recent 50 years; and to identify the drive power of the oasis development quantificationally. At the spatial structure,to clarify the dynamics of the oasis structure and to prove up the coupling mechanisms of mountain, oasisand desert ecosystems and the stability mechanism of oasis ecosystem and the safety protection; to build high efficiency and sustainable development model for oasis ecosystem. Combining with the progress of the engineering project and the industries development, we will research the ecological environment influences of some large projects,to build some different kinds of ecological demonstrationspots. Combining with period of time of some national large engineering projects
,to forecast the evolvement direction of the western arid environment and to put forward the management model and the control system for the ecosystem for the sake of the western exploitation and the sustainable development.