The forest at Helan Mountain was isolated about 1 500 years ago.The estimated population size of alpine musk deer( Moschus chrysogaster) in the forest were 227 and 183 individuals in the autumn of 1995 and spring of 1996, respectively.The musk deer distributed scatterly in the trees of the steep slopes,and the population densities were very low.We suggested that the population were on the verge of extinction.The population has being disturbed and threatened by lots of environmental factors since 1950s,an...