珍稀濒危植物桫椤种群生命过程及谱分析

根据种群生命表和生存分析理论，以高度级为基础编制了桫椤种群特定时间生命表，绘制了生存函数曲线，分析了种群的生命过程.结果表明:桫椤种群结构为前期增长、后期稳定类型.生命期望在第4龄级最大，此阶段种群生存质量相对较高.种群存活曲线属于典型的Deevey-Ⅲ型.种群生命过程有3个死亡高峰期，分别是第2龄级向第3龄级、第10龄级向第11龄级和第12龄级向第13龄级生长阶段.种群存活率随龄级增加呈单调减少，相应的积累死亡率呈单调增加，变动幅度为前期大、后期小;死亡密度函数曲线呈现前期下降、后期平缓稳定的特点，凹点出现于第4龄级.谱分析结果显示,桫椤种群数量波动性是大周期内有小周期的多谐波迭加，各周期作用基本上随周期的缩短而减小，基波的影响最显著.

Population life process and spectral analysis of rare and endangered plant Alsophila spinulosa.

According to population life table and survival analysis theory, the time-specific life table and the survival function curve of Alsophila spinulosa population were established and drawn based on height class, and the life process of the population was analyzed. The results revealed that the population structure of A. spinulosa was of the type ascending at early stage and stable at late stage. The peak of expected life appeared at the 4th age class, indicating the relative good survival quality at this phase, and the survival curve belonged to the typical form of Deevey-Ⅲ. There existed three death peak phases in the population life process, i.e., the growth stages from 2nd to 3rd age class, from 10th to 11th age class, and from 12th to 13th age class. With the increase of age class, the population survivability dropped down monotonously, and the accumulative mortality rose up correspondently. The variation extent was high in early phase and low in anaphase. The death density function curve displayed the characteristics of descent in early phase and stabilization in anaphase, and the concave point occurred at 4th age class. Spectral analysis showed that the quantitative fluctuation of A.spinulosa population was multi-harmonic superposition with large cycles containing small cycles. The influences of these cycles dropped with the diminishment of cycle length, and the effect of fundamental wave was most prominent.