基 于 生 命 表 的 大 兴 安 岭 兴 安 杜 鹃 (Rhododendron dauricum)种群数量特征及动态分析

Rhododendron dauricum is one of the main dominant species in the shrub layer of the Great Khingan Mountains. However, the demography analysis of the population is still in the blank. In this study, the population of wild R. dauricum with different elevations and forest types in Huzhong District of the Great Khingan Mountains was taken as the object. A static life table was compiled, the survival analysis functions were calculated, and population dynamics were analyzed by time series. The results showed that in the Larix gmelinii forest with low elevation gradient (600 m), there are more juvenile individuals (age class Ⅰ—Ⅱ) of R. dauricum, accounting for 67.31%. Their mortality and disappearance rate are low, and the survival rate is high. The survival curve is Deevey Ⅰ. Therefore, it is a growth population. The turning point of the population decline period is in the age class Ⅱ—Ⅲ, and the population number will increase in the future. In the Betula platyphylla forest with low and middle elevation gradient (600—900 m), there are more middle⁃aged individuals (age class Ⅱ—Ⅲ) of R. dauricum, accounting for more than 45%. Their mortality and disappearance rate are low, and the survival rate is high. The survival curve is Deevey Ⅰ. Therefore, it is a stable population. The turning point of the population decline period is between the age classes of Ⅲ—Ⅳ or Ⅳ—Ⅴ. Due to the restriction of population density, the population number will gradually decline in the future. In L. gmelinii forests with high elevation gradient (1200 m), the total number of individuals of R. dauricum is the smallest. The number of individuals at the age class Ⅰ is the largest, accounting for 33.52%, but their mortality and disappearance rate is higher, and the survival rate is lower. Moreover, the death and disappearance rate of individuals at the age class Ⅱ—Ⅴ is lower, and the survival rate is higher. The survival curve is Deevey Ⅲ. Therefore, it is a growth population, but the growth trend is weak. The turning point of the population decline period is at age class V, and the population number will increase in the future, but due to environmental constraints, the population number tends to be more stable. In conclusion, the population size of R. dauricum in the Great Khingan Mountains is stable overall. Elevation and forest type are important factors affecting the population number of R. dauricum. The B. platyphylla forest with an elevation of 600—900 m and canopy density of 45%—50% is the suitable habitat for R. dauricum, and R. dauricum is the main dominant species in shrub layer.