乌冈栎群落垂直结构与重要值分析

群落垂直结构和物种重要值是群落的重要特征,是认识群落的基础,在一定程度上反映物种的动态及群落的演替趋势。通过对不同地区乌冈栎群落的垂直结构与重要值的分析,结果如下:(1)乌冈栎群落垂直结构可分为乔木层、灌木层、草本层和层间,但草本层与层间结构都十分简单;群落垂直高度普遍较低,大致在4～7 m,群落郁闭度在0.6～0.75,乔木层盖度在80%左右,林层稀疏,并有林窗存在;灌木层垂直结构各地情况不尽一致,高度在1～2 m,整体而言其物种组成及垂直高度结构复杂性要大于乔木层。(2)各物种重要值结果表明,乌冈栎占有较高的重要值比例,是乔木层的绝对优势树种,其余重要值较大的物种大多属于亚热带山地森林常见树种如檵木、青冈、刺柏、乌饭树、满山红等;乔木层重要值比例较为集中在前10的树种,体现出群落优势种较为明显的局面;灌木层重要值比较分散,大多数灌木的重要值比例不高,这说明了该层物种多样性高的特点;乌冈栎的幼树幼苗在多数群落内均较少,导致其重要值较低,不利于乔木层的补充更新。

Analysis of the vertical structure and importance value of Quercus phillyraeoides community in different districts

Community vertical structure and species importance values are essential characteristics to understand the community, which can reflect the dynamic of species and the succession tendency of communities. The results of this paper show as follows. (1) The vertical structure of Q. phillyraeoides community could be divided into tree layer, shrub layer, herb layer and interlayer, but the structures of herb layer and interlayer were very simple; the height of vertical structure was about 4-7 m, and the canopy of community and tree layer coverage were about 0.6-0.75 and 80%, respectively, which meant the community structure was sparse and gaps existed. It is not the same of the situation of shrub structure in different districts as that of the tree layer. The height of shrub layer was about 1-2 m, and the complexity of species composition and vertical structure were more than that of tree layer. (2)The importance value of individual species indicated that Q. phillyraeoides was dominant species with high value, while other species with less significance than Q. phillyraeoides were subtropical forestry common trees such as Loropetalum chinense, Cyclobalanopsis glauca, Juniperus formosana, Rhododendron mariesii. The importance value in the top 10 of each community occupied the great mass of percentage in the tree layer, which could represent the reality of the structure; the importance value of individual in the shrub layer were not high, which meant the high species diversity in this layer. The importance value of Q. phillyraeoides was lower in the shrub layer than that of other species because of few seedlings, and was beneficial to the community refreshing.