*Rhododendron dauricum*(Ericaceae) population in the Great Khingan Mountains based on life table

*Rhododendron dauricum*)是大兴安岭森林群落灌木层的优势种,其种群统计研究尚属空白。以大兴安岭呼中区不同海拔和林型的兴安杜鹃种群为对象,编制了静态生命表,计算生存分析函数,采用时间序列分析种群数量动态。结果表明,低海拔梯度(600m)的落叶松林中,兴安杜鹃幼龄级(Ⅰ-Ⅱ)个体较多,占67.31%,且幼龄级死亡率和消失率较低,存活率较高,存活曲线为Deevey Ⅰ型曲线,为增长型种群。种群的衰退期转折点在Ⅱ-Ⅲ龄级,未来种群数量呈增长趋势。中低海拔梯度(600-900m)的白桦林中,中龄级(Ⅱ-Ⅲ)个体数量较多,占45%以上,中龄级死亡率和消失率较低,存活率较高,存活曲线为Deevey Ⅰ型曲线,为稳定型种群。种群的衰退期转折点在Ⅲ-Ⅴ龄级之间,由于种群密度制约,未来种群数量逐渐趋于衰退。高海拔梯度(1200m)的落叶松林中,种群个体总数最少。其中,Ⅰ龄级个体数量最多,占33.52%,但死亡率和消失率较高,存活率较低,Ⅱ-Ⅴ龄级死亡率和消失率较低,存活率较高,存活曲线为Deevey Ⅲ型曲线,为增长型种群,但增长趋势较弱。种群的衰退期转折点在Ⅴ龄级,未来种群数量呈增长趋势,但由于环境限制,种群数量更趋于稳定。可以认为,大兴安岭兴安杜鹃种群数量整体稳定。海拔和林型是影响兴安杜鹃种群数量的重要因素,海拔为600-900m,郁闭度为45%-50%的白桦林为兴安杜鹃的适宜生境,成为灌木层中的主要优势种。

*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.

*Rhododendron dauricum*|population quantitative|life table|elevation gradient|forest type