Tibetan ecosystem analysis based on 3S

The ecological environment of Tibet located in Qinghai-Tibetan plateau has great ecological meanings for global climate changes. GIS, RS and GPS are applied to constructing Tibetan landuse database in this study. And ecological index (El) is defined to evaluate the regional ecosystem status. The results show that: (1) the unutilized area and grasslands are the primary landuse of Tibet; (2) the Tibetan eco-environmental status is relatively good with El of 86.85; (3) the eco-environmental status of Lhoka is best with El of 99.62. The next are Chamdo, Xigaze, Nyingchi. Those of Nagri and Nagchu are inferior with El of 62.46 and 56.16; (4) there are six counties with excellent El, which is 8.22 percent of 73 counties. There are 51 counties with fine El, which is 69.86 percent of 73 counties, and 16 counties of general EI, which is 21.92 percent of 73 counties; (5) the ecological index (EI) can not embody the natural fragility completely. The more indexes should be considered in the El calculation equations to reflect the ecological environment more accurately.