珍稀濒危植物浙江楠种群结构分析

在样方数据调查的基础上,运用种群生命表、时间序列预测模型等方法,对浙江松阳地区浙江楠(Pheobe chekiangensis)的种群结构和种群数量动态变化进行研究.结果表明,松阳浙江楠种群在结构上大体呈“金字塔”形,幼树数量较大,中间径级和大径级个体数量稀少.生命表数据显示死亡率(qx)在第Ⅳ径级以前基本上为负值,说明大量幼苗在前期死亡.Deevey存活曲线属于Ⅲ形并且斜率较大,死亡率和致死率(Kx)起伏式波动,说明种群具有一定复杂性和不稳定性.时间序列预测分析表明在经历2、4和6个径级时间后,种群数量有明显减少的趋势.导致种群下降的主要原因可能是人为采伐、生境破碎化和在郁闭条件下幼苗种内竞争激烈等.

The population structure of the endangered plant Pheobe chekiangensis

Based on plot investigation, the structure and status of the Pheobe chekiangensis population in Songyang county, Zhejiang province were analyzed using the static life table and forecasting mode of time sequence. The results showed that the size class structure ratio of the P. chekiangensis population was in the pyramid-shape, indicating a large number of seedlings and saplings and a limited number of mid-class and large-class trees. The life table showed that the mortality rate (q_x) was minus value above the IV size class, implying that many seedlings died in the earlier life stage. The survival curve was of Deevey-III and dramatic changes in death curve and killing curve (K_x) were observed, indicating that the complexity and instability were in the process of natural regeneration. The time sequence analysis showed an obvious decline tendency in the Ph. chekiangensis population after 2, 4 and 6 diameter classes. The key threats to this species are most likely deforestation, habitat fragmentation and seedling intense intraspecific competition under the condition of canopy closing.