长江上游暗针叶林生态系统水文过程调节机制的研究

Correlation of forest and water, whose core is water movement and water cycling mechanisms, is one of eco-hydrological topics. Relying on project of regulating mechanisms of dark coniferous forest ecosystem of upper reach of Yangtze River on hydrological process (39930130), supported by National Science Foundation of China, on base of the first-hand data derived from Alpine Ecological Experiment of Chinese Academy of Sciences on eastern slope of Gongga Mountain and experiments on the spot, spatial and temporal distribution, movement mechanisms of water in dark coniferous forest ecosystem are analyzed and discussed broadly and deeply. Regulating laws of dark coniferous forest vegetation change on hydrological process are simulated by a physically-based distributed hydrological model. The research results can be an important theoretic and practical basis for the sustainable watershed management and rational utilization of water resources of upper reach of Yangtze River...1. Structure and Pattern of the Dark Coniferous Forest Ecosystem.Assisted by plant canopy imager (CI-110) and Differential Global Positioning System (DGPS) and Geographical Information System (GIS), some principles of fractal geometry, pipe model theory, landscape ecology and geo-statistic were employed to describe the structure and its canopy interception features in Abies fabri dark coniferous ecosystem at three scales of individual tree, community and landscape. Some statistic models between their structural index and interception function have been initiatively established, including the fractal dimension of tree's body and the crown projection patches, leaf area index (LAI), and index of pipe model obtained by analysis of trees' structures and communities or landscapes' patterns. Results show that, the surface and branching structure of Abies fabri are of typical fractal features, whose fractal dimension is 2.3232 and 1.8119 respectively. Therefore, such species is of poor shade-tolerance. The foliages and branches at the same height are laid out in direct proportion, and alternated in length and weight with height. The quantity of pipes in unit area is linearly correlated to foliages that they connect. LAIs of over-aged, mature, mid-aged and young Abies fabri communities are 5.41, 5.26, 5.31 and 5.47 respectively. Except mid-aged stands, LAI vary with season in the other three kinds of stands. Mainly limited by altitude, there are few landscape types in the watershed, and they rank with gradient along slopes. Being few disturbances, the diversity index of patches is smaller than 1 in dark coniferous forest landscape, and the mature or over-mature forest stands are the dominant patches in such landscape, and the young forest stands along river have relatively more complicated patch shapes...2. Impact Mechanisms of the Dark Coniferous Forest Ecosystem on Water Quantity.(1). Average rainfall in research site is 1937.5mm per year and 79.5 percent falls in wet season. Most of rainfall event is low intensity, low quantity. Average canopy interception rate of mature dark coniferous forest in research site is about 25%～30%. Difference of forest canopy interception between seasons is mainly caused by seasonal distribution of rainfall. There are near Correlations between forest canopy interception and rainfall classes, leaf area index and succession period of dark coniferous forest. .In dark coniferous ecosystem, rainfalls outside the stands is linearly correlated to that inside of the stands, but has exponential function relationship to canopy interception. According to partial relation analysis between canopy interception and rainfall, rain period, rain intensity, the rain period has more significant influence on interception, and the influence of rainfall is more significant than rain intensity, such phenomenon corresponds to the rain feature of long period and even intensity soundly in this region. The index of tree pipes, f, representing the capability of stem and branches to support foliages, is linear correlated to canopy interception. The index

在CERN贡嘎山站长期定位基础上, 以长江上游暗针叶林生态系统为对象，从水文物理过程和生物地球化学循环入手，重点研究森林生态系统对水分运动及水量转换、流域径流形成的调节机制；研究伴随水分运动及水量转换过程的主要水质要素迁移和土壤侵蚀机理。实现根系层与非饱和－饱和带水力传导度定量关系、根系层结构对优先流与基质流交换的影响机制、流域尺度水文生态过程耦合模型等理论的创新，从本质上揭示森林生态系统调节水文