Community structure and plant diversity of secondary forests in Shenzhen.

In order to rebuild the natural landscape with the native vegetation,this paper aimed to offer a model and a theoretical basis for the recent eco-landscaping forest construction from natural secondary forest in Shenzhen area.Based on field investigation,We set up 15 fixed plots whose area is 30 m × 40 m in Xiaomeisha,Yantian district,Paiya Mt.,Longgang district and Yangtai Mt.,Baoan district.The factors investigated include diameter at breast height of trees(DBH≥1.0 cm),tree's height,coverage and the number of shrubs and herbaceous with the method of grid sampled.All data are dealt with SPSS11.0.cluster analysis show that the current secondary forest in Shenzhen can be divided into 4 forms,i.e.,Cryptocarya chinensis+Sterculia lanceolata+Sinosideroxylon wightianum community,Schefflera octophylla+Litsea rotundifolia+Castanopsis fissa community,Cunninghamia lanceolata+Aporosa dioica+Psychotria rubra community,Cinnamomum burmannii+Albizia falcataria+Alstonia scholaris community.Comparing with research made in the Baiyun Mt.,Guangzhou and in Hong Kong,the species and the structure of secondary forest community are rather similar.It is also found that the percentage of trees with smaller diameter and the tree's height below 10 m is much more in the existing secondary forest.All communities follow log-series distribution model.The biodiversity index of four kinds secondary forest vary insignificantly,in which the S.octophylla+L.rotundifolia+C.fissa community has the highest species diversity,the mixed conifer C.burmannii+A.falcataria+A.scholaris community has the highest shrub species diversity.