关键词: 土地覆盖, 草地退化, 分布格局, 长江源区

Abstract: This paper describes three basic research approaches in ecological studies,and emphasizes on the importance of experimental approach,which should be considered as a basic research approach of agroecology.Hoviever,current experimental studies of agroecology in China needs to be strengthened, and more efforts are needed to improve experimental research facilities.Some suggestions are given for improving ex-perimental studies of agroecology in China.

Key words: land cover, grassland degradation, distribution pattern, Yangtze River headwaters area.