潭清苏铁的生境、种群结构与动态的研究

Studies on the Habitat,Population Structure and Dynamics of Cycas tanqingii

对小黑江流域潭清苏铁的生境、种群结构与动态进行了研究.结果表明,小黑江流域的自然地带性植被主要为热带雨林,海拔600m以下的原生植被为典型热带北缘季雨林,而海拔600～1000m的原生植被为山地雨林.其原生植被遭到破坏后,土壤流失严重,生态环境向干旱、贫瘠化发展,从而导致其次生植被都向山地雨林演化,加上人类活动的继续存在,不可能在短期内恢复成原生植被类型——热带季雨林或山地雨林.尽管其生态环境发生了显著的变化,但潭清苏铁的生存、繁衍正常.这也表明潭清苏铁对其环境变化有一定的适应能力.潭清苏铁种群的年龄结构基本呈金字塔形,属较稳定的结构.但是,种群的成年个体数明显偏小,成了潭清苏铁种群生存繁衍的 瓶颈 ,也反映出了潭清苏铁曾经遭受过严重破坏的事实,虽然潭清苏铁对生态环境的变化有一定的适应能力,但抗人为破坏的能力较弱.潭清苏铁生长发育很缓慢,种群恢复的周期较长,大约是30～40a.目前,潭清苏铁种群正处于恢复、上升阶段.就地保护可能是其最有效的保护途径之一.目前,潭清苏铁被列为国家一级保护植物,其分布区——小黑江流域已成为黄连山国家级自然保护区的一部分.如果其现有的生态环境得到有效保护,且在没有人为破坏的前提下,潭清苏铁不会沦为濒危物种.

This paper deals with the habitat,population structure and dynamics of Cycas tanqingii occurring in Xiaoheijiang river area.In Xiaohei river region,the virgin vegetation in the area below a altitude of 600 m is considered as a type of tropical seasonal rain forest in the northern margin of tropical Asia,and the virgin vegetation in the area with a altitude form 600~1 000 m is considered as a type of montane rain forest.After the primeval vegetation forms were destroyed,the two vegetation forms have been in a succession syndynamic from virgin vegetations to the same arid vegetations.Although the habitat change of C.tanqingii has taken place,the growth and reproduction of C.tanqingii is normal.So,population of C.tanqingii adapts itself to changed habitat to a certain degree.The age structure of the population of C.tanqingii takes on a stable shape of pyramid.However,the fact that mature trees in population is very few shows that the population might be seriously destroyed 30~40 years ago.Meanwhile,since the individual development of C.tanqingii is very slow and the restoration period of its population is as long as 30~40 years,so,few mature trees is a bottleneck for the existing and multiplying of population.The number of more young individual in population shows that C.tanqingii in Xioahei river area is in the status of population restoration.C.tanqingii is listed as the First Grade of National Conservation Plants in China.Conservation in situ is one of the most effective ways for C.tanqingii.Now,Xiaohei River area is a part of Huanglian Mountain National Reserve.Thus,C.tanqingii is not in severe danger on the premise of effective management.