Abstract: Analyses of the changes in desertified land area, water resource a vailability, 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 Sa ndy Land had a rapid expansion, but reversed since then. The annual runoff of Xi liaohe River decreased consistently, and in 1999, the middle reach at Tongliao s ection was dried up. In recent 20 years, the water table of Xihu Lake was decrea sed 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 c ause of these results was the change of land use pattern, i.e., the overuse of w ater resources for re-vegetation or cropland irrigation. Water resources reduct ion was the major challenge to the desertification reversion in Horqin Sandy Lan d.

Key words: fuzzy matter element, Huaihe River Basin, urbanization, eco-environment, coupling coordination.