新疆生态景观格局演变及其与气候的相互作用

Interaction of Evolution of Ecological Landscape Pattern and Climate Change in Xinjiang

应用1982～1993年12年的NOAA气象卫星遥感数据(分辨率为8km×8km),本文借助FVC(Frac-tionalvegetationcoverdata)植被指数分析新疆维吾尔自治区境内的生态景观格局.分析结果指出,全区12年绿洲(自然和人工)的平均面积占整个区域面积的18.48%,荒漠为37.2%,典型草原占10.27%,山地森林草原为3.39%,沙漠裸地占30.31%,湖泊占0.348%.与30年气候平均值相比,12年中年降水量全区增加了23.6mm,温度增加了0.28℃.有意义的是降水量增加最多的地区不是山区,而是在南疆西北部绿洲集中分布的地区.这表明了一个重要的事实,即在一定尺度的气候背景条件下,绿洲的植被覆盖对调节区域气候有着积极的作用,当下垫面的植被覆盖面积达到一定程度时,植被和气候之间的相互作用十分明显.同时,在降水量增加和温度升高的条件下,典型草原的面积呈扩大趋势.总的来说,从20世纪80年代以来至90年代初期的10余年间,新疆的气候趋向好转,植被覆盖状况有所改善,未发现有大范围沙漠化现象.

Fractional vegetation cover data (FVC) based on the annual maximum NOAA/AVHRR NDVI (Advanced Very High Resolution Radiometer normalized difference vegetation index) data and the ground meteorological data have been used to analyze the relationship between the temporal and spatial evolution of ecological landscape pattern and climate change in Xinjiang Autonomous Region, China from 1982 to 1993.It is found that during this period, the average oasis cropland or low-damp forest-shrub meadow area occupies 7.5% of the whole region, desert 25.70%; temperate semi-arbor desert 21.70%; temperate shrub and semi-shrub desert (8.36%;) alpine subalpine desert steppe 7.71%; temperate gramineous and ruderal steppe 7.63%; mountain forest steppe 2.13%; high-cold barren 8.93%; high-cold low semi-shrub desert 9.08%; water/ice 1.26%. Compared with the 30-year (1961-1990) climatology, the 12-year average annual surface air temperature and precipitation over the whole region increase by 0.28℃ and 23.6 mm respectively. The maximum increase of precipitation did not occur over the mountain region, instead it occurs over the region with a concentrated distribution of oases, suggesting the positive role of oases in adjusting regional climate. The area of temporal steppe also increased with the growith of precipitation and temperature. Together, these results demonstrate that, during the 12-year period, the condition of vegetation cover was improved and large-scale desertification did not occur in Xinjiang.