Forestland changes and climate response in the Three Gorges Reservoir Area based on RS and GIS

In order to make a detailed analysis of forestland changes and their climate responses during the last 50 years, the authors obtained information for the year 2002 of the distribution of forestland by the application of a new auto-extraction method with relatively high precision. The authors took TM, SPOT and MSS images as well as topographic maps, assisted by manual revision, as our fundamental information sources. And the forestland distribution maps of previous periods (years of 2000, 1995, 1986, 1973 and 1953) were also obtained by the manual interpretation method, which was carried out in the way of searching for dynamic spots. Meanwhile, analysis was made on the process of the dynamic changes of forestland during the last 50 years. Moreover, on the basis of data collected from 1 915 stations throughout China, the meteorological data in the Three Gorges Reservoir Area were obtained by the interpolation method and also the climate responses to the changes of forestland were analyzed.Resultsshow that each kind of forestland area in the Three Gorges Reservoir Area has experienced a process of sharp reduction--mild reduction--relatively great reduction--slow restoration during the last 50 years. The response of the annual average temperature to the forestland changes is not significant. However, the changes of annual average rainfall are closely related with those of the forestlands, although its changes lag behind the forestland changes and have abnormality in certain period.