北京山区辽东栎林的径级结构、种群起源及生态学意义

 北京山区的辽东栎(Quercus wutaishanica)林径级结构的调查分析结果表明，辽东栎林是稳定性的群落类型，其更新主要通过萌生来完成。能够与辽东栎长期共存的伴生种有色木(Acer mono)、大果榆(Ulmus macrocarpa)、大叶白蜡(Fraxinus rhynchophylla)等。萌生在辽东栎种群中十分普遍，除辽东栎伐桩、枯木和大树根际有较多的萌生茎干外，多年生实生苗也有萌生现象发生。辽东栎林的更新在辽东栎总体种群的幼树阶段(径级2)存在着明显的瓶颈现象，但萌生特性使辽东栎林在更新时或受到干扰后形成较大的萌生种群，使辽东栎的大幼树能够得到迅速的补充，顺利地通过瓶颈进行更新，保持群落的相对稳定。一定数量的辽东栎实生种群的存在对于维持辽东栎的遗传多样性、种群整体活力和群落的稳定，提高辽东栎种群对环境变化的反应能力等方面有着十分重要的生态学意义。

SIZE STRUCTURE, ECOLOGICAL SIGNIFICANCE AND POPULATION ORIGIN OF QUERCUS WUTAISHANICA FOREST IN BEIJING MOUNTAINOUS AREA

Size structure analysis of Quercus wutaishanica (Liaodong oak) forest in a mountainous area of Beijing city indicates that while the oak forest is rather stable its regeneration mainly relies on stem base sprouting. The size structure of populations of Acer mono,Ulmus macrocarpa, and Fraxinus rhynchophylla ,the main associated species in the oak forests,indicate that these are also able to co exist the oak. The phenomenon of sprouting from the bases of the oak stems is very common in these forests. In addition to sprouting from stumps and bases of dead and aged individuals,new stems of seedlings and saplings also usually sprout basally. The size structure of the oak populations shows a clear bottleneck at the sapling stage (size class 2) during forest regeneration. However,through its sprouting ability,the number of stump sprouting,size class 3 individuals is large enough to make up the shortage of saplings and complete the regeneration of populations. It is as a result of this resprouting process that the forest is able to maintain its stability. On the other hand,the cohort of seedlings,though limited in size,has ecological significance through its role in maintaining genetic diversity,the vigor of the oak population as whole and the stability of the communities in which it occurs as well as improving the oak's adapting ability to the environmental changes.