民勤荒漠生态退化动态特征研究

通过设置样方，调查研究了民勤荒漠生态退化的动态特征。结果表明，民勤绿洲区地下水位正在急剧下降，天然植被面积逐年减少，盖度正在明显下降，随着水资源退化和植被退化，沙漠化土地面积正在扩大，沙漠化程度正在增强。荒漠区水资源退化引起植被退化，植被退化进而导致沙漠化过程加强。随着植物的大面积死亡和稀疏化，生态环境越来越恶化。植被退化加之开垦使得极重度、重度沙化土地面积扩大，中轻度沙化土地面积相对减少。目前地下水位下降的主要原因，一是农业灌溉用水量增大，二是上游入境水量逐年减少。实践证明，在干旱沙漠中造林，尤其是打井提取地下水造林，只能加速沙漠化和生态环境退化的过程。

Study on Dynamic Degenerate Ecological Characteristic of Desertification in Minqin

This article through the establishment sample,the investigation and study the dynamic characteristic on desert ecology degenerated of Minqin.The result indicated that,the Minqin oasis area subsoil water level suddenly is dropping,the natural vegetation area reduces year by year,coverage obviously is dropping,the desert land area is expanding and the desert degree is strengthening with the water resources degeneration and the vegetation.Decrease of water resource aroses vegetation degenerate,while vegetation degenerate accelerates desertification.With death of plants and spar sitist of the vegetation,the ecological environment has been deteriorating more and more.The vegetation degeneration and as sart result that the most serious desertification and the serious desertification land extend area,relatively the area of low-grade desertification declines.The main cause for falling water table down is as follows:the first one is allocation of water to agriculture more and more;the second is water from upper reaches of Shiyang river is smaller and smaller.The practice proves:the forestation in arid desert,especially forestation by pumping water from underground,can but accelerate behavior of desertification and environment degeneration.