四川小凉山珙桐更新及种群稳定性研究

Regeneration and stability of Davidia involucrata population in Xiaoliangshan Mountain,Sichuan Province.

在对四川省小凉山珙桐种群的林内环境、种群分布格局及年龄(径级)结构进行详细调查的基础上,分析了林区内珙桐的更新情况及种群稳定性.结果表明:林下环境不适宜导致的幼苗发生率低下是珙桐种群更新不良的关键;一旦幼苗储备建成以后,珙桐种群发育过程具有良好的连续性,并能在群落中维持较长时期的稳定状态;因此对现有生境的简单保护并不能有效地遏制珙桐种群的衰退进程;不破坏种子库的人为干扰能改善林内小环境,并使珙桐种子充分接触土壤,协助Ⅰ级幼苗储备的建立以及种群的天然更新,进而从根本上促进珙桐种群的发育.提出了珙桐濒危的小种群效应机制假说,并指出从更大的范围来讲,人工促进珙桐各局域种群间的基因交流将有利于其作为1个物种的恢复.

The inside forest situation and stability of Davidia involucrata population were studied based on the field survey of mi , distribution pattern and age structure of the species in Xiaoliangshan Mountain, Sichuan Province. The results showed that low seedling density caused by unfavorable microenvironment was one of the most important factors for the poor inside forest situation of the population. In addition, the population could develop into the higher stage smoothly and keep stable in the community for a long period once the seedling bank has been established. Some conclusions can be made that the population size bottleneck effect and founder effect are still to be overcome for the species. Passive protection of the habitat is not enough to keep the species from extinction effectively. Moderate human disturbance without destroying the seed repertory is an effective approach to improve the microenvironment and facilitate the building of seedling reserve, thus then these will benefit the natural regeneration, thus the endangered status of the species can be hampered effectively. We also proposed a small population size hypothesis as endanger mechanism of the species and put forward that gene flow among meta-populations would greatly help the re-flourishing of the species.