Comparative Studies Of Community Structure And Diversities Of Main Forest Types Of Ecological Service Forest In Ningbo

The ecological forest plays an important role in maintaining of ecological stability, biodiversity conservation, sustainable development, and consequently providing services for human needs. This study has been conducted in the ecological forests of Ningbo, Zhejiang Province in eastern China. Total of 100 typical subtropical forest plots were investigated through standard forest inventory method from April 2013 to October 2014, with consideration of the survey data conducted in 2007. In each sampling plot, all individuals of tree, shrub and herb layers were measured. Then the forest regeneration structure and different measures of species diversity such as species evenness (J), richness (S), Shannon-Wiener diversity (H) and Simpson dominance (D) indices were calculated at each level of whole community, tree, shrub and herb layers for each sampling plot. After that 100 plots were classified into different forest types. Pearson’s correlation coefficients were used for the correlations among S, D, J and H, while one-way ANOVA was used for the significant differences of S, D, J and H among different layers as well as different forest types. The main findings of the study were:(1) The main forest types of ecological forest in Ningbo are evergreen broadleaved forest (EBF), confinerous and broadleaved mixed forest (CBMF), shrub forest (SF), and coniferous forests including Pinus massoniana forest (PMF), Pinus taiwanensis forest (PTF), and Cunninghamia lanceolata forest (CLF). The EBF were dominated by Fagaceae, Lauraceae and Theaceae families, while the dominant species in CBMF were belonging from Pinaceae and Taxodiaceae families, but Pinaceae species were only found in PMF and PTF, and Taxodiaceae species were the main species in CLF. Among the studied forests, EBF had covered the largest area (i.e.,36%), followed by CBMF (i.e.,16%), PMF (14%), and CLF (14%), while PTF and SF had covered only 4 and 2%, respectively, and the remaining 14% was covered by other forest types.The species richness of the tree layer followed the following pattern, i.e., EBF> CLF>CBMF>PMF>PTF>SF. The species richness of shrub layer followed such pattern as; EBF>CLF>CBMF=PMF>PTF>SF. In the herb layer, the pattern of species richness were as; EBF>CLF>CBMF>PMF>PTF>SF.(2) By considering the whole ecological forest, the correlation of S with each of H and D was strong than that of J with each of H and D in most of the vegetation layers as well as at community level. With respect to different forest types, the opposite trend of correlations were found to that of lastly described. In addition, it was found that H has the strong correlation with other three indices, followed by D at each of different layer and forest type level. Thus, H followed by D index can be considered as the suitable measures of species diversity in the studied forests, but S and J also need to be included as additional factors.(3) At tree layer, the H, D, S and J in each of the EBF and CBMF were significantly (P<0.05) higher than other forest types. With respect to the shrub layer, there were no significant differences (P>0.05) for four indices among all forest types, except H and D were significantly different in CLF and PTF. There was no significant difference for each of four indices in herb layer among all forest types. The four indices of shrub and herb layers with in each forest type were significantly higher than tree layer, with exception of non-significant difference for J of shrub and tree layers in each of EBF and CBMF.(4) In the EBF, the evergreen broadleaved tree species, such as Schima superba, Cinnamomum camphora and Castanopsis eyrei, followed inverted J-shaped structure, thus, indicating to become stable, while deciduous broadleaved trees such as Liquidambar formosana and Quercus acutissima were found to be decreasing with forest age. With respect to CBMF, the tree species such as Liquidambar formosana, Pinus massoniana and Cryptomeria fortunei were found to be decreasing while Schima superba, Machilus thunbergii and Castanopsis eyrie were going to be stable with the forest age. The dominant species in PMF and PTF were found to be diminishing, and deciduous trees such as Choerospondias axillaris in both forests showing irregular development, but some evergreen tree species including Lithocarpus glaber, Cyclobalanopsis glauca, etc. were gradually increased. In CLF, the dominant species such as Cunninghamia lanceolata were found to be increasing and becoming stable with the forest age, while other species were found in the small DBH classes only.(5) The community structure of the main ecological forest types in Ningbo region were mostly clumped type with most of the individuals are small-sized with height ranges between 2 to 6 m and DBH<7.5 cm. According to the basic stages of secondary succession, the studied ecological forests may be divided into preliminary (SF), early succession (PMF and PTF), middle succession (CBMF) and late succession (EBF) stages. Hence the ecological forests in Ningbo region were likely to be in the transition of middle-later succession stage, thus, the community structure was more stable than each of the middle and later succession stage.