[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 ow nosy, a 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.