Aims

 针对九龙山国家级自然保护区南方铁杉(Tsuga tchekiangensis)种群的分布特点, 设置了10个具有代表性的样地。以种群生命表及生存分析理论为基础, 编制了南方铁杉种群的静态生命表, 绘制了存活曲线、死亡率曲线、消失率曲线、生存率曲线、累计死亡率曲线、种群死亡密度曲线和危险率曲线, 分析了种群数量特征; 同时结合谱分析方法, 分析了南方铁杉种群数量的动态变化。结果表明: 1) 南方铁杉种群结构存在波动性, 幼年阶段的个体较丰富, 成年个体数量相对较少, 种群趋于Deevey Ⅱ型。2) 南方铁杉种群死亡率和消失率曲线变化趋势基本一致, 均出现两个高峰, 一个出现在第5龄级阶段, 另一个出现在第15龄级阶段。3) 南方铁杉种群的生存率单调下降, 累计死亡率单调上升, 生存率下降趋势前期高于后期, 累计死亡率则相反。4) 4个生存函数曲线表明, 南方铁杉具有前期稳定、中期锐减和后期衰退的特点。5) 种群动态的谱分析显示, 南方铁杉种群动态除受基波影响外, 还存在着明显的小周期波动, 谐波A3处周期的波动与南方铁杉的高生长有关; A6处周期的波动与外界环境变化有关; A8处周期的波动与南方铁杉进入生理衰退期有关。

POPULATION QUANTITATIVE CHARACTERISTICS AND DYNAMICS OF RARE AND ENDANGERED TSUGA TCHEKIANGENSIS IN JIULONGSHAN NATURE RESERVE OF CHINA

Aims Our objective was to investigate population quantitative characteristics and dynamics of Tsuga tchekiangensis, which is listed as a Chinese national third protective plant with a small geographic distribution in subtropical forests of Jiulongshan Nature Reserve, Zhejiang Province, China. Methods Ten plots (20 m × 20 m) were investigated along different ridges from low to high altitude. We developed a static life table of T. tchekiangensis population based on the population life table and theory of survival analysis. Survivorship curves, mortality rate, killing power, survival rate, cumulative mortality rate, mortality density and hazard rate were determined, and population dynamics were analyzed using spectral analysis. Important findings There were abundant young but fewer old individuals. Population structure fluctuated. The survival curve of the population was Deevey type Ⅱ. Two peaks of mortality rate and killing power existed in the lifespan: the 5th and 15th age class periods. The population survival rate of T. tchekiangensis decreased monotonically, whereas the cumulative mortality rate increased monotonically. Meanwhile, the cumulative mortality rate significantly increased during the 13th age class period, up to 98%. Four survival functional curves showed that the T. tchekiangensis population grew stably at young age, decreased very quickly in middle age and declined in old age. Spectral analysis of the population showed that there was a marked periodic fluctuation in the process of natural regeneration.