文峪河上游河岸林的群落结构与多样性特征

Community Structure and Plant Diversity Characteristics of Riparian Forests on Upper Reaches of Wenyuhe River

文峪河上游垂直河岸40 m的区域存在泛滥平原和山坡两种地貌。在实地踏查和河岸林群落划分的基础上,对河岸带两种地貌的森林群落结构与多样性进行了差异比较,以期为该区河岸带宽度确定提供植被依据。结果表明,56个样地分别属于13种群落,泛滥平原的林分密度、物种丰富度与植物多样性都显著大于毗邻山坡,而林木断面积与均匀度在两种地貌之间的差异不明显;两种地貌的物种组成相似性较高,共有物种达75.13%,乔木优势种基本一致,但华北落叶松在山坡的优势地位更突出;34种植物仅出现于泛滥平原,多为喜湿种类,13种旱生植物仅出现于山坡;基于以上考虑,洪水对本区植被的影响范围在20 m之内。

There exist two geomorphologic types（landscapes） on the area 40 meters away from the upper reaches of Wenyuhe River,i.e.floodplain and slope.The plots are divided into two areas： 0—20 meters and 20—40 meters away from the riparian.The floodplain is in the former area while the slope in the latter.On the basis of field survey and riparian forest community classification,the differences of forest community structure and diversity of the two landscapes were compared,serving for riparian width speculation.The results are as follows.With TWINSPAN and DCA,the 56 plots belong to 13 kinds of community,and the stand density,species richness and plant diversity of riparian forest are higher than that on the neighboring slope,but the differences of tree breast-area and evenness of the forests between the two landscapes are not significant,while the species similarity of the two landscapes is high,the common species is accounted to 75.13%.The dominant tree species are similar in the two landscapes,but Larix principis-rupprechtii grown on slope is more outstanding than that on floodplain.There are 34 plant species exist only on floodplain,most of which are wetland plants.13 xerophytes species are merely exist on slope.Based on the situation mentioned above,it is deduced that the influence of flood on plant flora is limited to the area 20 meters away from riparian.