濒危植物长柄双花木自然种群数量动态

STUDY ON NUMERIC DYNAMICS OF NATURAL POPULATIONS OF THE ENDANGERED SPECIES DISANTHUS CERCIDIFOLIUS VAR. LONGIPES

运用种群生命表、生殖力表、Leslie矩阵模型和时间序列预测分析方法 ,研究了濒危植物长柄双花木 (Dis anthuscercidifoliusvar .longipes)种群的动态变化过程 ,揭示了长柄双花木各龄级植株的数量动态规律。结果表明 :长柄双花木为缓慢负增长型种群 ;种群的净增殖率、内禀增长率以及周限增长率都较低 ,世代平均周期较长 ;Leslie矩阵模型和时间序列预测分析均表明在未来 5 0年内长柄双花木各年龄级种群数量会出现波动性的消长 ,但其种群总数将逐步下降。

Disanthus cercidifolius var. longipes is an endangered plant species which is only distributed in Jinggang Mountain, Junfeng Mountain and Guanshan, Jiangxi Province,Longquan, Zhejiang Province, and Mangshan, Hunan Province, China. At present, its population is small and decreasing. In order to better understand its decline, we studied the population dynamics of this species using static life tables, fecundity schedules, Leslie matrices and time sequence analysis based on an in_depth investigation of age structure, seed production and seed germination rate. The results are as follows: Net reproductive rate ( R 0), intrinsic rate of increase ( r m ) and finite ratio fineries (λ) are 0.833 7, -0.004 7 and 0.995 3, respectively. Values of the separameters ( R 0<1, r m <0, λ<1) indicated that the population is decreasing. The Leslie matrix model predicted that over the next 50 years the number of populations would decrease from 227 1 to 764, i.e., only 30% will remain. The results of the time sequence analysis agreed with the Leslie matirix model prediction. The key threats to this species are most likely deforestation and habitat fragmentation.