Abstract: Human activities, resulted in land use and land cover changes, are main causes of global environmental changes. In 1990s, Yunnan had experienced very active economic development and environmental changes. This paper assessed the land use and land cover change between 1990 and 1998 in Lancang watershed by applying remote sensing, Geographic Information System(GIS) and other disciplines.It showed that the state designated forestland had increased from 64.9% in 1990 to 66.4% in 1998, however forest cover (natural forest and artificial forest with closed canopy >30%) had decreased from 52.6% in 1990 to 35.3% due to large-scale logging, infrastructure development, cash crop plantation, shifting cultivation and over-collection of fuelwood and construction material, which resulted in change of forest structure and loss of biodiversity.

Key words: Lancang watershed

摘要： 由人类活动引起的土地利用和地被覆盖的变化是地球上环境变化的主要原因。上世纪90年代是云南省经济发展和环境变化的活跃时期。本文通过现代卫星遥感技术、地理信息系统和其它多学科手段相结合，系统调查评估了云南澜沧江流域1990年至1998年间土地利用和地被覆盖的变化，结果显示流域中林业用地面积从1990年的64.9%增长到1998年的66.4%，但是森林有林地(郁闭度>30%的天然林和人工林)从1990年的52.6%减少到1998年的35.3%。并且分析大规模商业性森林砍伐、基础建设、经济作物的种植、刀耕火种、薪材过度采集和砍伐建筑用材等引起了森林的结构的显著变化和退化，从而导致了生物多样性的下降。

关键词: 澜沧江流域, 土地利用和地被覆盖, 驱动因子, 生物多样性