关键词: 槭叶铁线莲, 年龄结构, 数量动态, 生存分析,  时间序列模型

Abstract: Clematis acerifolia is an endangered national key protected wild plant species in China (Class II), which is distributed only on the limestone cliffs in northern Taihang Mountains. Based on field investigation, the shoot age data of 458 individuals were obtained from 11 sites. Ages of the individuals were estimated based on the number of bud scale scars on the longest shoot. Accordingly, the age structure and dynamics of the populations were quantitatively analyzed. The results showed that: (1) The population age structure was a typical pyramid pattern, with few young individuals at age class 1; (2) The population declined between age class 1-2 and 6-7, but had the ability to renew and maintain; (3) The population survival curve was N_x=259e^-0.4x, which was close to Deevey Ⅱ. The first peak of mortality rate (q_x) and disappearance rate (K_x) curve emerged at the age class 5. After that q_x remained stable and K_x rose rapidly; (4) The greatest increase or decrease of survival rate and cumulative mortality rate happened to the first six age classes, and such changes tended to be gentle after age class 7. The first peak of risk function λ_(ti) curve appeared in the age class 6. The death density f_(ti) was generally low, with the maximum value at the age class 3; (5) The prediction analysis of time sequence model suggested an increase in the number of middle-aged and old-aged individuals after the time of age class 2, 5, and 8. The population showed a high elimination rate in young age class, stable in middle age class, and depressed in old age class. The age structure was relatively stable at present, but with early signs of depression that lack of young age class individuals was the main cause limiting the population growth of Clematis acerifolia.

Key words: Clematis acerifolia, age structure, quantity dynamics, survival analysis, time sequence model.