高山植物圆穗蓼的繁殖资源分配

Reproductive Allocation of an Alpine Perennial,Polygonum macrophyllum

于海北高寒草甸生态系统定位站附近的一个西向山坡上,以高寒灌丛草甸中海拔不同的4个地点的圆穗蓼为研究对象,分析圆穗蓼的繁殖特征在海拔梯度上的变化规律,以探讨高山植物在极端环境下的资源分配策略。结果发现:(1)随海拔升高,圆穗蓼的植株高度先增大后变小,营养器官生物量和繁殖器官生物量均呈现增加的趋势,但三者与海拔梯度的相关性不显著,而且繁殖分配在4个不同海拔取样地点间差异不显著;(2)个体越大,圆穗蓼分配到繁殖器官的绝对资源比例也显著增加,但在海拔较低的3个取样地点内,繁殖分配随海拔升高呈增加的趋势,这可能与高寒灌丛草甸土壤的潜在肥力较高而导致圆穗蓼不存在资源限制有关;(3)圆穗蓼在4个取样地点均存在繁殖阈值,繁殖阈值与海拔的相关性不显著,但仍然表现出随海拔升高而略有降低的趋势,表明海拔较高居群的植株达到开花繁殖需要的营养积累较小。研究表明,由于海北站的土壤肥力较高,4个取样地点的圆穗蓼不存在个体大小依赖性的繁殖分配和随海拔升高而增加的繁殖分配;而高海拔取样地点较低的繁殖阈值表明高山植物的有性繁殖比营养生长具有更为重要的意义,强调了有性繁殖对高山植物的重要性。

Reproductive allocation of Polygonum macrophyllum and its altitudinal variations were studied in four sample sites from an alpine shrubby meadow on a west-facing slope near the Haibei Alpine Meadow Ecosystem Station in the Qinghai-Tibet Plateau,to further understand the patterns of plant resource allocation under alpine environments.Our results showed that,with the increasing altitude,the plant height of P.macrophyllum increased gradually but decreased in the highest altitude sample site,and the biomass of both vegetative and reproductive organs increased gradually.However,the plant height,the biomass of vegetative and reproductive organs had no significant correlation with the altitude respectively.There was also no significant change in reproductive allocation among the four sample sites along the altitudinal gradients.With the increased individual size,the biomass of reproductive organs increased greatly in the four sample sites,and the reproductive allocation also slightly increased,except in the highest altitude sample site,which showed insignificant decrease in the reproductive allocation.The above outcomes indicated no resource limitation in the growth and reproduction of P.macrophyllum,which could result from the high potential soil fertility in alpine shrub meadow.We found a reproductive threshold of P.macrophyllum in each of the four sample sites,and the relationship between altitude and reproductive allocation was insignificant but weakly negative,suggesting a reduced minimum biomass of vegetative organs for reproduction in the higher altitude sample site.Based on these results,we then draw a preliminary conclusion that there was no size dependent reproductive allocation due to the high potential soil fertility and an increased resource allocation to reproduction with increased altitude in P.macrophyllum around the Haibei Alpine Meadow Ecosystem Station,but more and further investigations are needed to give a general conclusion.In addition,the reduced reproductive threshold suggested the priority of sexual reproduction over vegetative growth in high altitude sample sites,emphasizing the importance of sexual reproduction in alpine plants.