Abstract: 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.

Key words: thinning effect, Larix olgensis plantation, simultaneous equations model., diameter distribution, parameter prediction model