Abstract: This paper studied the land use and land cover changes between 1990 and 1999 in Tacheng township,Weixi County of Northwest Yunnan.The results showed that there was little change in main land use type and in spatial structure within 10 years,with the land still predominantly forested.However,the forest structure had changed from predominantly high dense canopy to middle canopy and open canopy,among which the open canopy increased from 9.93% to 18.30%,with a net gain of 8.37%,high dense canopy lost 5.35% and middle canopy lost 5.15%,resulting in the decrease of forest quality.The landscape of land use/land cover changes mainly happened in southeast and southwest of Tacheng above altitude 3 400 m.The decrease of landscape diversity and landscape fragmentation had great impacts on the habitats of Rhinopithecus bieti in the region.

Key words: Coniferous forests, Species diversity, Low elevation region, Three Gorges area