中国北方沙漠化土地时空演变分析

对2000年中国北方256×10⁴ km²区域内沙漠化土地的遥感监测结果表明:沙漠化土地总面积现已达到38.57×10⁴ km²,其中轻度和潜在沙漠化土地13.93×10⁴ km²,占沙漠化土地面积的36.1%;中度沙漠化土地9.977×10⁴ km²,占25.9%;重度沙漠化土地7.909×10⁴ km²,占20.5%;严重沙漠化土地面积6.756×10⁴ km²,占17.5%。与20世纪50年代后期到70年代中期和80年代后期的沙漠化土地发展状况相比,目前我国沙漠化土地演变趋势具以下特征:(1)沙漠化土地仍在蔓延,面积已由1987年的33.895×10⁴ km²增加到了2000年的38.569×10⁴ km²,13a中净增4.674×10⁴ km²;(2)沙漠化土地继续呈加速发展的趋势,年平均发展速率从20世纪50年代后期到70年代中期的1560 km²、70年代中期到80年代后期的2100 km²发展到90年代的3600 km²;(3)部分旱农区以及农牧交错地区沙漠化土地出现明显逆转,但荒漠草原地区沙漠化土地面积继续扩大,并且程度有所加剧。

Time-space Evolution of Desertification Land in Northern China

It was disclosed by former researches that the desertification land in northern China developed at rate of 1 560 km² per year from late of 1950s to middle of 1970s,and till late of 1970s the already desertified land had reached 17.6×10⁴ km²,the light degree and potential desertification lands had reached 15.8 10⁴ km²;During the following ten years the developing rate was up to 2 100 km² per year,and till late of 1980s the already desertified land had reached 33.3×10⁴ km².In order to further disclose the status and developing trend of desertification land in China from then on and provide dependable bases for the strategy making of desertification control,another field investigation and monitoring with remote sensing to the desertification status in 256×10⁴ km² area of Northern China was conducted in 2000.The results showed that the total desertified land area had increased to 38.576×10⁴ km² from 33.895×10⁴ km² in 1987,among which the light degree and potential desertification land was 13.93×10⁴ km²,occupied 36.1% of the total;the middle degree was 9.977×10⁴ km²,occupied 25.9%;the serious was 7.907×10⁴ km²,occupied 20.51%;the very serious was 6.756×10⁴ km²,occupied 17.5%.The developing rate of desertification land was further raised to 3 500 km² per year during 1990s.In details,although the desertification in part of agricultural and agro-pastoral areas inversed distinctly,the area of desertification land in desert steppe and steppe desert continuously extended and the degree intensified.