中华山蓼不同海拔居群的繁殖分配研究

Reproductive allocation in a dioecious perennial Oxyria sinensis(Polygonaceae) along altitudinal gradients

研究了具有克隆繁殖和雌雄异株繁育特性的中华山蓼Oxyria sinensis Hemsl.在5个不同海拔居群的繁殖分配。结果表明:(1)雄株高度和茎叶总生物量仅在海拔2780m的居群显著高于雌株,在另外4个居群与雌株高度和茎叶总生物量均不存在显著差异;雄株地上部分总生物量在海拔较高的3个居群显著高于雌株的地上部分总生物量;雄株的花生物量和繁殖分配在海拔1978m的居群与雌株没有显著差异,但在另外4个居群均显著高于雌株,表明在海拔较高的地区,中华山蓼增加了对雄性植株的资源配置,可能是对海拔较高地区不可预见性降雨和降低昆虫访花频率的适应。(2)雌雄株高度、地上部分总生物量和茎叶生物量以及雌株的花生物量和繁殖分配随海拔升高表现出降低的趋势,但雄花的生物量和繁殖分配随海拔升高显著增加,进一步证明中华山蓼在海拔较高地区的居群增加了对雄性资源的投资。(3)雄雌株繁殖分配受个体大小制约(个体大小依赖性),但并不支持'植物开始繁殖必须达到一定的大小(阈值)'的观点。这可能因为中华山蓼具有较强的无性繁殖能力,而同一植株上不同分株间能通过地下根状茎达到资源共享,因此中华山蓼分株的开花繁殖不需要达到一定的大小。

The reproductive allocation （P.A, the ratio of flower biomass to total aboveground biomass） of Oxyria sinensis Hemsl., a clonal dioecious perennial, was compared among five populations along an altitudinal gradient from 1978 m to 2780 m. The goal of this study is to answer the following questions： （1） What is the variation in the reproductive allocation of O. sinensis？ （2） Does variation in reproductive allocation correspond to an altitudinal gradient？ （3） Is the reproductive allocation of male and female O. sinensis correlated to environmental factors？ We found that reproductive allocation to ramets decreased with increasing vegetative biomass in both male and female plants. Increasing altitude corresponds to a decrease in height of ramets, total aboveground biomass, and biomass of vegetative organs in both male and female plants. The total aboveground biomass of male ramets was significantly higher than female ramets in the populations at the altitudes of 2422 m and 2780 m. The biomass of flowers and reproductive allocation of male ramets were significantly higher than of female ramets at all popu- lations except at the lowest altitude population, which indicated male ramets allocate more biomass to reproduc- tion than female ramets. Our results do not support the idea of an invariable minimum vegetative biomass for reproduction, probably because resource can be shared among ramets within one ramet system of a clonal species, and the pattern of RA in O. sinensis might be an adaptation to the unpredictable rain and decreased pollinator visitation in the higher altitudinal populations.