Studies On Community Characters Of The Evergreen Broad-Leaved Forest In Beishan Mountain Of Jinhua, China

Chinese evergreen broad-leaved forest, the main part of the evergreen broad-leaved forest in the world, has the large distribution area and various types, and has an important role in protecting the region ecological environment, maintaining sustainable economic and social development. For a long time, because of inadequate understanding of evergreen broad-leaved forest in its function and effect, it had been damaged and caused series of problems, such as soil degradation, function decline, pests'frequent. Therefore, the research work of evergreen broad-leaved forest community characteristic appears especially important and urgent. This paper is a report about studies on floristic characteristics, community physiognomy, structural features, distribution pattern, intraspecific and interspecific competition, population restoration and species diversity of the evergreen broad-leaved forest in Beishan mountain of Jinhua. The research was based on the field investigation and quantitative ecology methods. The main obtained results are as follows:(1) There were 144 species,66families and 115 genera of vascular plants, including 8 ferns,2 families,2 genera and 2 species of gymnosperms,58 families,105genera and 134 species in the evergreen broad-leaved forest community of Beishan Mountain in Jinhua. The evergreen trees of Fagaceae, Lauraceae and Theaceae occupied a dominant position in 81 woody plants. And these characters reflected community structure and composition features of subtropical evergreen broad-leaved forest in China. The floristic characteristics of seed plants in the community had complicated composition significant transition properties. The floristic analysis of dominant families showed that tropic elements occupied the dominant position, and the temperate components were also important. The floristic analysis of genera showed tropical components also had important advantages, but more of them were temperate components. The high buds plant in the community had an absolute advantage, total 78.68%. The analysis of leaf characters showed most of the plant were small and medium-sized, orthophyll, entire and sample leaf. Whatever flora composition or community appearance, they were all reflected the characteristics of evergreen broad-leaved forest in subtropical northern margin, and showed the relatively warm and humid climate characteristics.(2) The vertical structure of the evergreen broad-leaved forest could be divided into four levels, including tree layer with 49 species, shrub layer with 84 species, herb layer with 26 species and inter layer with 34 species. The species diversity of the four layers was analyzed by using Shannon-Wiener index, Simpson index, and Pielou index. The results showed that:each index had the same change trend, and represented general rules which were shrub layer>tree layer>inter layer>herb layer in the subtropical evergreen broad-leaved forest community. The important value analysis of superiority species showed that the building-group trees in the community were Schima superba, Castanopsis sclerophylla, Liquidambar formosana, Pinus massoniana, and as representative trees, they reflected the basic appearance and characteristics of subtropical evergreen broad-leaved forest community. The distribution pattern of dominate trees was studied by using patchiness index, dispersion index, negative binomial parameter et al. The results showed that aggregation features of level structure in the forest were obvious, and there were 14 cluster distribution populations in 15 dominate trees, and the gathered degree of Schima superba, Castanopsis sclerophylla, Cinnamomum camphora, Ligustrum lucidum, Eurya muricata et al. were higher, while Quercus acutissima, Liquidambar formosana, Quercus fabric and Cunninghamia lanceolata showed lower gathered degree, especially, Pinus massoniana showed uniform distribution. The distribution pattern was concerned with the biological characteristics, and the intraspecific and interspecific competition in community succession process.(3) The age structure and development of dominant population were categorized into four regeneration types by the method of space for time sere. After that, combining the biological with ecological characteristics of that species, the diagnosis of succession stage of this community was carried out. The results were as follows:(1) Inverse-J type species, such as Schima superba, Castanopsis sclerophylla and Cinnamomum camphora, were strong shade-tolerant and dominant species in climax forest, they could regenerate through seedling bank or sprouting under the closed forest canopy; L type species, such as Loropetalum chinensis, Ligustrum lucidum and Ewya muricata, were broad-leaved evergreen small trees or large shrubs, and they were the main components of Iaccio wood layer and shrub layer species in climax community; Sporadic (multimodal) type species, such as Liquidambar formosana, Quercus acutissima and Castanea henryi, had the opportunity and volatility to the population structure, reflecting the characteristics of top pioneer species; Spindle type species, such as Quercus fabri, Pinus massoniana and Cunninghamia lanceolata, were high positive and the pioneer species in the successional sequence, but they had showed a recessionary signs because of the lack of updated population in the community. (2) The successional stage of the forest was classified as a late seral stage community that would develop into a climax community dominated by Schima superba and Castanopsis sclerophylla.(4) Based on the important value and 2×2 contingency table, interspecific association of 15 tree species in the evergreen broad-leaved forest of Beishan mountain were examined by using variance ratio (VR),χ2 text, association coefficient (AC), co-occurrence percentage (PC) and point related coefficient (Φ). The results showed that the interspecific relation of 15 species took on a not significantly positive coupling, which reflected instability of the community structure, and the number of positive coupling was slightly more than the negative coupling, most of the interspecific relation had weak coupling and some even had no relationship, such as Pinus massoniana and Cunninghamia lanceolata, Cunninghamia lanceolata and Symplocos sumuntia, Vaccinium bracteatum and Castanea henryi. This laxity feature between various groups reflected the community had not form a relatively stable harmonious collocation mechanism and was at the prophase of the top succession stage.(5) The niche characteristics of 15 dominate species in the evergreen broad-leaved forest were determined and analyzed by using niche breath, niche overlap and niche similarity proportion. The results showed that Schima superba, Liquidambar formosana, Eurya muricata, Castanopsis sclerophylla, Pinus massoniana and Cunninghamia lanceolata had bigger niche breath value of Levins and Shannon-Wiener in the community, the niche overlap and niche similarity proportion of dominate trees were higher, and the number of niche overlap value which was greater than 0.8 was 15 in 105 pairs constituted by 15 dominate species and 76.2% was greater than 0.4 and the trees which had big niche breadth often had higher niche overlap and niche similarity proportion value. Schima superba and Liquidambar formosana, Castanopsis sclerophylla and Pinus massoniana, Pinus massoniana and Eurya muricata which had bigger niche overlap value in the community, they existed competition of resources utilization each other. Schima superba and Eurya muricata, Loropetalum chinensis, Symplocos sumuntia, Vaccinium bracteatum located in different levels in the community, schima superba could share resources with them. And Eurya muricata, Loropetalum chinensis, Symplocos sumuntia, Vaccinium bracteatum had similar bioecology characteristics; they would compete with each other, when the resources were short, but share in enough resources. The positive pioneer species such as Pinus massoniana, Cunninghamia lanceolata, and Liquidambar formosana would gradually withdraw from the community, while the evergreen trees such as Schima superba, Castanopsis sclerophylla and Eurya muricata would have further development, and the niches of various populations would also change until the community reaches the stable succession climax.