grassland area and its cause in Inner MongoliaA case study on Duolun County of Xilin Gol League

Variation of grassland area in the Duolun County of Xilin Gol League was presented by combining field survey and remote sensing technology and its causes were discussed in this study. The results of this study showed that grassland area in Duolun County was fluctuant from 1971 to 2007, indicating that the grassland area decreased from 227 640.93 ha in 1980 s to 166 929.43 ha in 1990 s, and restored to grassland area of the 1980 s in 2000 due to conversion of cropland to forest and grassland. Under the climate warming and drying, human disturbance was key factor affecting the grassland area. Plenty of grasslands were reclaimed into croplands and were substituted by the lakes and marshes in 1990 s when the climate was warm and humid, resulting in the decrease of grassland areas. In 1980 s, grassland degenerated and deserted because of overgrazing. Although the rainfall decreased, the grassland had been gradually restored because of better management from 2000 to 2007.