穿龙薯蓣种群生命表的研究

通过对吉林省三岔子林业局的野生穿龙薯蓣(Dioscorea nipponica)年龄结构的调查,编制出了其野生种群的静态生命表。结果表明:3~15年间,死亡率非常低。而15年之后,特别是25年之后的死亡率明显升高;年龄结构,在30年之前,各龄级的株数基本符合正态分布规律,而30年之后却偏离了这个规律,表现为各龄级的株数成直线减少;生命期望值在30年之后明显增大。这充分表明了该地区穿龙薯蓣的种群正趋于衰退,该物种日趋濒危。

STUDY ON LIFE TABLE OF DIOSCOREA NIPPONICA POPULATION

By investigation on age structure of wild Dioscorea nipponica in Sanchazi Forestry Bureau of Jilin Province, we established static life table of wild Dioscorea nipponica population. The results showed that its mortality rate was very low during the ages of 3~15 years old, but after that began to increase, especially evident after 25 years old. The distribution type of the individual number of different age classes belonged to normal distribution within 30 years. 30 years later, however, its distribution type diverted from normal distribution, and showed that the number of individuals of each age class decreased linearly. The mean of longevity was also found obviously getting higher after 30 years. In brief, this life table fully indicates that population dynamic of Dioscorea nipponica in this region was declining and that this species is being endangered.