利用1967年航片数据、1986和2000年两期遥感TM数据,对长江黄河源区高寒生态系统分布格局变化进行了分析,并结合源区气候变化观测数据,分析了源区高寒生态系统变化与气候的关系和陆面生态系统变化对源区水文过程的影响。结果表明:过去40a来,长江源区高覆盖草甸、高覆盖草原和湿地面积分别减少了13.5%、3.6%和28.9%,黄河源区高覆盖草甸、高覆盖草原和湿地面积分别减少了23.2%、7.0%和13.6%,江河源区低覆盖草甸、草原和沙漠草地面积均不同程度地增加;长江、黄河源区气温变化率分别为0.27和0.31℃/10a,降水的变化趋势在长江、黄河源区分别以0.36和0.07mm/a的速率递增,气温持续升高和由此引起的冻土退化是导致高寒生态系统退化的主要因素之一;陆面生态系统退化对源区水文过程影响显著,在降水没有明显变化的情况下,长江、黄河源区径流系数分别由1960年代的0.16和0.28下降到21世纪的0.12和0.21,且降水-径流关系减弱,出源径流趋于减少,洪水发生频率显著增加,水源涵养指数持续减小。如何应对气候变化,维护源区高寒生态系统功能,已成为迫切需要关注和解决的关键问题。

The distributive pattern of the alpine ecosystem in the source regions of the Yangtze River and Yellow River was analyzed based on the aerial photo in 1967 and the TM remote sensing data obtained in 1986 and 2000; the relationship of changes in the alpine ecosystem with climate was then analyzed based on the climatic observation data; and the effect of changes in the land surface terrestrial ecological system on the hydrological process of the river source region was analyzed using runoff coefficient, rainfall-runoff relationship, flow duration curve, and water conservation index etc.Results show that the alpine ecosystem persistently degraded over the last 40 years, the area of high coverage alpine meadow and alpine steppe decreased, while wetland shrunk and desertified meadow increased.The permafrost thawing due to temperature rise is one of the main factors which led to the degradation of the alpine ecosystem.The changing of temperature was significantly negatively correlated with the areas of high coverage alpine meadow, alpine steppe and alpine swamp meadow.The degradation of land surface terrestrial ecosystem has significantly affected the hydrological process in the source regions; under the condition that precipitation changed slightly, the relation between the persistent decline of runoff coefficient and precipitation-runoffattenuated.the frequency of flood increased, and the outflow and water conservation index persistently decreased.It is urgent to pay much attention to cope with the climatic change and to sustain the alpine ecosystem's function in the source regions.