科尔沁沙地沙漠化土地恢复面临的挑战

对科尔沁沙地近50年来沙漠化土地面积、水资源可利用性、土地利用与草地植物生产力的变化进行了分析.结果发现：科尔沁沙地的土地沙漠化在经历了20世纪50—80年代中期的快速发展之后，80年代后期发生了逆转.在过去的50年中，西辽河径流量持续减小，1999年在西辽河中游的内蒙古自治区通辽市段断流;近20年来，位于科尔沁沙地腹地的西湖水位下降近10 m, 2001年干涸.科尔沁沙地草场的地上生物量由1937年的520 g·m^-2下降到2005年的197 g·m^-2.产生这种结果的主要原因是土地利用方式的变化，即基于灌溉的沙漠化治理规模的扩大和灌溉农田面积的增加,导致用水量增加.这也是科尔沁沙地实现土地沙漠化持续逆转面临的严峻挑战.

Challenge to the desertification reversion in Horqin Sandy Land

Analyses of the changes in desertified land area, water resource availability, land use, and plant productivity in Horqin Sandy Land in recent 50 years showed that from 1950 to the late 1980s, the land desertification in Horqin Sandy Land had a rapid expansion, but reversed since then. The annual runoff of Xiliaohe River decreased consistently, and in 1999, the middle reach at Tongliao section was dried up. In recent 20 years, the water table of Xihu Lake was decreased by about 10 m, and dried up in 2001. The above-ground biomass of grasslands decreased from 520 g·m-2 in 1937 to 197 g·m-2 in 2005. The main cause of these results was the change of land use pattern, i.e., the overuse of water resources for re-vegetation or cropland irrigation. Water resources reduction was the major challenge to the desertification reversion in Horqin Sandy Land.