【目的】明晰自然演替下枫香(Liquidambar formosana)种群的数量动态特征,为南京紫金山地区森林的可持续经营提供参考。【方法】以南京紫金山南麓受人为干扰较小的固定样地中枫香种群为研究对象,记录样地内所有枫香个体的胸径、树高、冠幅等指标;根据调查样地内枫香个体胸径的大小,划分为9个径级(以0~7.5 cm径阶为径级Ⅰ,后每间隔5 cm划分径级直至径级Ⅸ),用径级来对应种群个体的龄级,绘制枫香种群年龄结构图,并用结构动态指数定量描述种群数量动态。通过编制植物种群静态生命表,绘制种群存活率、死亡率和消失率曲线,利用生存分析函数和线性平稳时间序列对该种群的结构特征现状及未来变化趋势进行分析和预测。【结果】①枫香种群个体年龄结构为“金字塔”型,在干扰下种群整体的龄级结构数量变化指数为0.02,表明种群个体数量在当前演替阶段能够维持正增长。②种群存活曲线趋于Deevey-Ⅰ型,种群个体生存率逐渐下降,死亡率、消失率、累积死亡率和危险率总体上逐渐上升,死亡密度则趋于稳定。③时间序列模型的预测结果表明枫香种群能够在未来较长的演替时间内仍呈增长趋势。④枫香树在胸径达到≥32.5~37.5 cm后可能逐渐进入寿命后期阶段,抗外界环境干扰能力较差。【结论】作为北亚热带、暖温带区域地带性树种,枫香种群在南京紫金山地区能够保持较多的个体数量以及完整的年龄结构,具有较强的天然更新能力,这使得枫香种群在未来演替阶段有占据先锋树种马尾松(Pinus massoniana)种群生态位的可能。但是枫香种群个体在胸径达到Ⅶ龄级(≥32.5~37.5 cm)后逐渐进入生理寿命,抗外界环境干扰能力较差。因此,为进一步发挥紫金山地区景观功能,建议加强对胸径达到32.5 cm的枫香个体的保护力度,增加该种群的抵抗力稳定性和生态空间扩展潜力,促进森林群落的进展性演替。

【Objective】The aim of this study is to evaluate the quantitative population dynamics of Liquidambar formosana under natural succession to provide a theoretical basis for the sustainable forest management on Zijin Mountain in Nanjing, China.【Method】Using the L. formosana population in a fixed sample plot on the southeastern foothill of Zijin Mountain in Nanjing as the research object, the indices of diameter at breast height (DBH), height, and crown width of all individuals were recorded. Subsequently, the DBH of the L. formosana population was divided into nine diameter classes, which were used as age class surrogates to examine the population structure. An age structure diagram of L. formosana population was constructed and the population dynamics were described quantitatively using the structural dynamic index. Finally, the structural characteristics and change trends of the population were analyzed and predicted by compiling the static life table, constructing the survival, mortality, and disappearance rate curves using the survival analysis function and linear stationary time series.【Result】(1) The individual age structure diagram of L. formosana population was a “pyramid” shape, and the quantitative variability dynamic index of the age structure under intervention was 0.02, indicating the population is able to maintain a positive growth in the current succession stage. (2) The survival curve of L. formosana population was inclined to Deevey-Ⅰ, where the individual survival rate slowly decreased with an increase in age, while the mortality, disappearance, cumulative mortality, and hazard rates increased, and the death density diminished. (3) The predicted results from the time-sequence model showed that L. formosana would continue to grow in a lengthy succession in the future. (4) L. formosana is expected to enter the later stage of life as the DBH reaches ≥32.5-37.5 cm, and the ability to resist the interference from the external environment is relatively poorer.【Conclusion】L. formosana is a zonal tree species in northern subtropical and warm temperate regions and has a strong natural regeneration ability, with the ability to retain many seedlings and a complete age structure on Zijin Mountain in Nanjing. Therefore, the L. formosana population may occupy the niche of the pioneer species Pinus massoniana population in a future succession stage. However, it is worth noting that the individuals in the L. formosana population gradually reach their physiological life span when the DBH reaches age class Ⅶ (≥ 32.5-37.5 cm), and their ability to resist the interference from the external environment is poor. Accordingly, it is suggested to strengthen the protection of L. formosana individuals whose DBH reaches 32.5 cm to further improve the scenic splendor of Zijin Mountain, increase the resistance stability and ecological space expansion potential of the population, and promote the progressive succession of forest communities.