城市化背景下珠江三角洲常绿阔叶林群落结构及植物多样性

Effects of urbanization on community structure and plant diversity in evergreen broad-leaved forests of the Pearl River Delta

随着城市化进程的加快,城市中存留森林的演替过程也发生明显变化。选取高度城市化的珠江三角洲为研究区域,以地带性群落常绿阔叶林为研究对象,选择城区(帽峰山、西樵山和大岭山)和郊区(鼎湖山、象头山和南昆山) 6个样地,分析城郊梯度上的植物群落结构和植物多样性指数。结果表明:城区森林包括31科42属46种,郊区森林包括44科75属96种,郊区样地的物种数高于城区样地的物种数;城区优势种明显,多为耐旱耐贫瘠种类,郊区无明显优势种,多为喜湿耐荫种类;城市森林中的Margalef指数、Shannon指数和Pielou指数显著低于郊区森林,城郊森林植物多样性的差异主要反映在乔木层。城市化降低了常绿阔叶林的植物多样性,促进了物种的均质化。

Rapid urbanization greatly influence succession of the remaining forests in cities. The effects of urbanization on plant community structure and species diversity in the remaining forests of southern China remain unclear. This study was conducted to examine the effects of urbanization on the community structure and diversity of the evergreen broadleaved forests in the Pearl River Delta by investigating species composition in arbor,shrub and herbaceous layers and calculating diversity indices of species abundance( Margalef index),diversity( Shannon index) and evenness( Pielou index) in six forests( including three urban forests and three suburban forests).There were 46 species and 42 genera belonging to 31 families in the urban forests,while 96 species and 75 genera belonging to 44 families in the suburban forests. The urban forests contained dominant species,which are mostly drought and nutrient poor-tolerant. In contrast,there was no obvious dominant species in the suburb forests,with most species in these forests being hygrophilous and shade-tolerant. Three kinds of diversity indices,including Margalef index,Shannon index,and Pielou index,were significantly lower in the urban forests than that in the suburban forests. Differences in plant diversity and community composition were mainly in the tree layer.Our results suggest that urbanization reduces plant species diversity and promotes species homogenization in the evergreen broadleaved forests.