Based on the comprehensive statistical assessment model with analytical hierarchy process and global principal component analysis (AHP-GPCA model) and RS/GIS, the changes of ecological environment in Qinghai-Tibet Plateau from late 1970s to 2000 were comprehensively assessed, and then the change of ecological environment and its spatial distribution were discussed. The assessment units were county and river basin, the assessment indicators were temperature, precipitation, normalized difference vegetation index (NDVI), glacier density, marsh density, lake ratio, population density and desertification ratio. The results showed that the change of ecological environment in Qinghai-Tibet Plateau was strong from late 1970s to 2000, and the environment of most counties deteriorated; the area of environmental deterioration in serious and middle levels were 31. 8% of the total area of Qinghai-Tibet Plateau, and the area in light level were 14. 5% , and the area of environment improved was 14. 5% ; the three principals were desertification ratio, glacier density and NDVI by global principal component analysis, and the accumulative contribution rate of them was more than 70%, so they could stand for the above eight assessment indicators; the river basin with serious environmental deterioration was mainly heartland of Qinghai-Tibet Plateau, Tsaidam Basin and the zone around Qinghai Lake, the most serious was Golmud and the most improved was southeast areas of Tibet; the change of ecological environment showed the multi-level structure from the edge to heartland and the extreme development trend to different directions; the counties with the ecological environment improved mostly distributed in the regions with glacier concentrated, and the local climate, ecological environment, change of water resource in part counties were very complicated under the influence of glacier change from late 1970s to 2000. Finally, the advantages of comprehensive assessment with AHP GPCA model and RS/GIS were discussed. The method could give consideration on both subjective and objective weights, decrease the duplicate information, and visualize the results.%运用层次分析和全局主成分分析结合的综合统计评价模型(AHP-GPCA模型),以县域和流域为评价单元,以气温、降水、归一化差异植被指数(NDVI)、冰川密度、湿地密度、湖泊率、人口密度、荒漠化率等数据为评价指标基础,基于GS/GIS对20世纪70年代末期至2000年青藏高原生态环境变迁进行综合评价,并探讨了研究区生态环境总体变化和空间分异特征.结果表明:从20世纪70年代末期到2000年,青藏高原生态环境变迁较为剧烈,重度中度恶化面积占青藏高原总面积的31.8％,轻度恶化面积占14.5％,好转的地区面积占13.5％,反映青藏高原地区生态环境自20世纪70年代末期以来总体恶化,仅有部分县域生态环境好转；依据全局主成分分析得到的三个主成分分别是荒漠化、冰川密度和NDVI,其累计贡献率超过70％,基本能够代表最初获取的8个指标；生态环境退化程度最为严重的流域主要在青藏高原腹地、柴达木盆地以及环青海湖地带,恶化最为严重的流域为格尔木地区,生态环境好转程度最大的流域为藏东南地区；青藏高原环境变迁呈现由边缘地区向腹地恶化的多层次结构,并呈现向两个极端方向发展的特征,其中生态环境转好的县域多分布在冰川较为集中的地区,反映了从20世纪70年代末期到2000年在冰川变迁影响下部分县域的局地气候、生态环境、水资源变化的复杂性.最后探讨了RS/GIS和AHP-GPCA模型进行综合评价的优势,认为该方法兼顾了评估主客观权重,减少了信息重复,使结果具有直观化的特点.
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