【作者】 孙自永；

【导师】 徐恒力；

【作者基本信息】 中国地质大学 ， 环境工程， 2006， 博士

【摘要】 最近50a来，中国西北干旱区生态环境不断恶化，不仅制约了当地的社会和经济发展，而且影响着整个北方地区的生态安全，并对中国中、东部地区的环境构成威胁。为改善这种生态环境状况，各级政府投入了大量物力和人力，启动了一系列的生态保护与建设工程。要使这些投入发挥最大的生态效益，必须查清西北地区生态系统的长期演化趋势，了解人类活动究竟能在什么层次和多大程度上影响生态系统的演化，据此制订更为科学合理的生态保护和建设的战略决策。因此，西北干旱区生态系统演化趋势及其机制的研究是涉及国家生态安全的重大科学问题，对西北各级地方政府生态保护与建设目标及措施的制订也具有重要的指导意义。 由于生态系统外界环境变化的随机性、生态系统—环境间反馈关系的复杂性、生态系统变化机理的不明确性，基于生态模型对生态系统的演化趋势进行预测存在着较大的不准确性，并且随预测时间变长，这种不准确性增大。以历史资料为基础进行外推的方法则对资料的时间长度有极强的依赖性，只有具备足够长时间序列的观测资料，才能提取出较大时间尺度上生态系统的演化信息，对未来较长时期内生态系统的演化趋势进行外推。但在有关干旱区生态系统演化的研究中，因资料积累不足等原因，目前通常只能获得较短时间内(几年或最多几十年)的相关资料。因此，提出不依赖于观测资料时间长度的新方法，利用较短时期内的资料，对西北干旱区生态系统的演化趋势及其机制进行分析，不仅具有重要的实践意义，也是当前理论研究的一个难点。 在上述背景下，论文以系统科学思想为指导，基于生态系统时空关系和尺度效应的分析，提出了利用较短时间内的植被格局资料提取生态系统大时间尺度上演化趋势的方法。利用这种方法，选取中国西北干旱区典型内陆河—黑河流域下游额济纳盆地作为研究区，对该区生态系统不同时间尺度上的演化过程进行了分离；然后分别分析了大时间尺度和中、短时间尺度上生态系统演化的特点、驱动机制及其景观学表现；最后，对研究区生态系统的演化趋势及荒漠在未来的分布格局进行了推演。 1．生态系统演化的时空关系及尺度效应分析 以系统科学思想为指导，结合分形理论和等级系统理论，对系统有序度和形态、状态、功能间的关系，植被空间格局计盒维数的生态学意义，生态系统多重分形结构与系统等级间的对应关系，生态系统时空尺度间的对易关系进行了理论探讨，得出如下结论：更多还原

【Abstract】 In the last 50 years, the ecological deterioration developed in the faster and faster speed, and became more and more serious in arid regions, NW China. Ecological deterioration in the regions not only restricts the harmonious development between economy and society, threatens the survival of the people, but also blights the stabilization of the society and the solidification of different nations, and even threatens the whole environment in Northern China. Therefore, there has been no time to delay for the ecological protection and restoration in the arid regions, NW China. To avoid wasting of resources, the ecological protection and restoration must be based on the good understanding of evolution trend of ecosystem and its causes.The traditional method to analyze the long-term evolution trend of ecosystem, e.g. extrapolation method, need long time series data of ecosystem history. However, in the areas, only few discontinuous data about ecosystem history are securable, and the data are mostly about the very recent history, no longer than several decades. An alternative method, namely ecological model, is very inaccurately for randomicity of environmental disturbance and non-linear mechanism exiting in ecosystem. It is necessary to develop a new method to analyze the long-term evolution of ecosystem and its causes according to the shot-term data about ecosystem history.Based on the research results in the past, this paper discussed the method how to get the information about the long-term evolution of ecosystem according to the shot-term dynamics of vegetation pattern. As a case in Ejina basin, the long-term and short-medium term evolution of ecosystem, its morphologic effect, and its driving forces were analyzed. The positive feedback mechanism in short-medium evolution of ecosystem was then discussed according to the fluctuation characteristics of environmental element at micro-scale. Employing spatial-temporal scales symmetry of ecosystem as theoretical basis, this paper predicted the long-term evolution trend of ecosystem in the area. At last, the object, principles, and measures of ecologic protection and restoration for the area were put up.1. The separation of long-term effect and short-medium term effect of ecosystem evolution更多还原