Land use and land cover changes on the county scale -A case study of the Suzhou Oases in Hexi Corridor

A study on land use/land cover changes was carried out according to land resources classification system of 1:10 0000 from the Resources and Environmental Database of Chinese Academy of Sciences that was based on two composite Landsat 5 TM (Thematic Mapper) images of band 4, 3, 2 taken in 1988 and 2000 by GIS. The results show that: The land use pattern was dominated by unused land(56.19%), cropland(27.47%)and grassland(12.19%) in 2000. Water area, rural residences, woodland and land for urban construction only occupied 4.15% in total. The land use pattern of each town was also very different; In the 12 years between 1988 and 2000, the landscape fragmentation increased for both the mean patch area and the perimeter of cropland, woodland, grassland and unused land decreased. The changes in land use structure showed that cropland and water area had evidently increased in the same manner as the land for urban and rural use while grassland, woodland and unused land tended to decrease. It also showed a trend of speedup in urbanization and in the deterioration of the ecological environment. The application of such indices as land use change amount, land use change ratio and relative land use change rate ratio can present the characteristics of land use changes in Suzhou from different considerations. The differences among different regions are reflected in all these indices and the advantages of relative change rate in indicating land use changes are evident.