不同光环境下薇甘菊形态和生理可塑性及其响应研究

Morphological and physiological plasticity responding to different light environments of the invasive plant,Mikania micrantha H.B.Kunth

研究了华南地区外来入侵种薇甘菊Mikania micrantha H B Kunth不同光环境下形态和生理可塑性及其适应性响应。通过模拟开阔地段、林缘、大林窗、小林窗、林下等不同生境的的光照环境,并设计一个干扰实验,分析了薇甘菊的生长、碳同化以及生物量分配如何对光环境作出适应性响应。研究了当干扰发生时,薇甘菊如何对光环境的变化做出形态和生理可塑性响应。通过对其各项生物量分配及气体交换等指标的观测,在小林窗光照环境下薇甘菊生长缓慢生物量积累较少,但是如果一旦受到干扰,光照环境得到改善,薇甘菊将在很短的时间内通过适应性形态和生理可塑性响应,迅速体现出较强的入侵性。这也可能是入侵植物薇甘菊"坐待对策(sit and wait strategy)"的生动体现:如果外界环境不利,暂且先保持繁殖体(种子或者根茎),一旦条件成熟(发生干扰条件得到改善或者遗传变异或者生态生理的积累),就会迅速爆发。所以我们一方面,不用担心郁闭的森林会被薇甘菊入侵,但另一方面也要注意干扰会引起光照等环境条件的改变,使得原来潜伏于林下的薇甘菊繁殖体重新变得富有入侵性。

The morphological and physiological plasticity,and adaptability of the invasive plant Mikania micrantha H.B.Kunth,responding to different light environments were studied.Light gradients were set,which stimulated the natural irradiance environments of open sites,the fringe of forest,big gap,small gap and understory respectively,and a disturbing experiment was designed.The growth,allocation of biomass,assimilation,plasticity and adaptation to the light environments M.micrantha responding to light were surveyed and analyze.How the invasive plant responded to the light environments when the disturbances occurred was studied also. The seedlings of M.micrantha grow slowly and less biomass accumulated under small gap.But the experiments exchanging the plants from the shade to sun regime showed that the photosynthetic parameters of M.micrantha could resume to the levels those of the controls soon,and become invasive again.It is also a vivid representation of＂sit and wait strategy＂of invasion of M.micrantha. Therefore,on one hand,it is not necessary for people to worry about if M.micrantha can invade the close forest,on the other hand, the natural or human disturbances may change the light environments of understory,and make the latent reproductive organs invasive.