| 其他摘要 | Black-and-white snub-nosed monkeys (Rhinopithecus bieti) distribute in a restricted area of the Trans-Himalayas between the Mekong and Yangtze River, and between 26o14’N-29o20’N and 99o15’E-99o37’E. It was once listed as one of the world’s top 20 most endangered primates in 2002. There are about 1700 individuals in 15 groups remained in the habitat between 4 200 (north)-2 600 m (south) asl. Tibet is the northernmost range of the species and harbored about 300 individuals in three groups. Based on previous reports and our field survey, we identified the fir forest and the mixed conifer forest as suitable habitat of the monkey. Summer grazing lands and farmlands, which were made by local people from cutting and burning the fir forest and the mixed conifer forest at the high and low altitude belt, replaced its suitable habitat. Although wildlife is not killed by Tibetan people who practice Buddhist teachings, R. bieti lost its habitat continuously in recently decades associated with the extension of rangelands and farmlands, as well as firewood collection etc. The monkey live mainly in primary fir forest and the mixed conifer forest, to evaluate the status of the monkeys’ habitat, we employed GIS and RS software to identify the habitat types with five Landsat TM/ETM+ satellite imagery in winter of 1986, 1992, 1997, 2001 and 2006 years respectively. The work resulted in: 1) the size of summer grazing lands, farmlands, and fir forest was 13 100 hm2, 6 400 hm2, and 30 500 hm2 in 2006 respectively; 2) during the past 20 years (1986-2006), the size of fir forest (including primary fir forest and the mixed conifer forest) decreased by 14.6% (5 200 hm2), summer grazing lands and farmlands increased by 47.2% (4 200 hm2) and 14.3％(800 hm2) respectively; and 3), during the past 20 years, the number of firry forest patches increased by 68.4%, the mean size of firry forest patches decreased by 49.3% (from 15.1 to7.6 hm2), the largest patch index of firry forest decreased 54.9%; the patch richness had no change, but the Shannon's diversity index and the Shannon's evenness index increased by 2.7% respectively. These indicate the degree of habitat loss and fragmentation increased sharply during the past 20 years. We further used Spearman rank correlation coefficient to analyze the relationship of the size of fir forest, rangelands and farmlands with demographic data (such as number of households, villager population，average household size and livestock inventories). The results shown that the size of fir forest, rangelands and farmlands are significantly (positively or negatively) correlated with number of households, villager population, and livestock inventories. As the local people still employ traditional production modes, the results imply that the reduction and fragmentation of habitat for R. bieti was driven by human population growth and its increasing activities (Multiple regression, R2 = 0.972), The increased economic activities (enlarged farmlands, rangelands and livestock inventories) resulted in the habitat loss, degradation and fragmentation. On the other hand, the polyandrous marriage system (only exist in parts of Tibet) practiced by the local villagers are positive for habitat conservation, since this can reduce resource consumption (such us firewood, number of room, rangelands, farmlands) per capita in large households (that is, the number of occupants) than in small households. Furthermore, the growth in household number was much slow than population growth between 1983 and 2003, this is also positive for habitat conservation. As the Tibet population of R. bieti had been genetically divided as an isolated subpopulation. More research works and conservation actions are very important for this area . |
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