关键词: 退化草原, 线虫丰度, 磷输入, 氮输入, 群落组成

Abstract: Based on the topographic maps (1∶50 000) in 1955, MSS images in 1972, and TM images in 1986 and 2000, the dynamic changes of land use during lately 50 years in Three Gorges Reservoir Area were quantitatively analyzed, with their driving forces discussed. The results showed that during lately 50 years, the structure of land use in the study area changed obviously, with a decrease of woodland, water area and unused land, and an increase of cultivated land, grassland and construction land. During the periods of 1955-1972, 1972-1986 and 1986-2000, woodland had a persistent and gradual decrease, grassland and cultivated land underwent a process of increase-decreaseincrease and of increase-increase-decrease, respectively, construction land increased continually, while water area and unused land kept decreasing. Policy, economic development, and population growth were the main driving factors of the land use change in the study area.

Key words: phosphorus application, degraded grassland, nitrogen application, community composition, nematode abundance