| This paper is a report about studies on floristic analysis, community structural features, distribution pattern, inter-specific association and niche of the major species, biodiversity, numerical classification, and dynamics of the evergreen broad -leaved forest in Jiulianshan National Nature Reserve of Jiangxi Province. The research is based on the theory and methods in floristic geography, community ecology, population ecology, mathematics ecology, plant ecological niche theory, biological statistics and computer technology. The main obtained results are as follows:The community of the evergreen broad-leaved forest is typical in the subtropical forest of South China, with an evergreen physiognomy. The flora is rich with transitional features, the flora had come floristic constituent before Quaternary and retains many floristic elements before Quaternary, and there were many rare and endangered plants in the community. The forest communities consist mainly of tropical and subtropical families and genera. Dominant families were mainly Fagaceae, Lauraceae, Theaceae, Styracaceae, Ericaceae, Magnolicceae, and etc., which were also dominant taxa.The quantity characteristics of plant species were analyzed and evaluated based on importance value. The forest communities were relatively lofty with significant, and their horizontal distribution was heterogeneity. The vegetation was a combination of natural forest, secondary natural forest and silvicultural rehabilitation. Some evergreen broad-leaved communities were matured or being renovated. Various hardwood trees were also encountered with high frequency, such as Liquidambar formosana, Alniphyllum fortunei, Betula luminifera etc.. These species with numerous individuals recruited into canopy gaps and forming evergreen and hardwood broad-leaved forests. The age structure and developments of dominant population were analyzed by the method of space for time sere. The results were as follows: the age structure of some population was stable or increasing, and that of the rest was moving from being stable to being declining.The spatial distribution pattern of the main 28 dominant trees was studied by using aggregate indices, variance ratio and the Possion distribution methods. The results showed that the spatial distribution pattern of the 28 dominant trees in the forest were all aggregated pattern in population and they were the Possion distribution of all the plots. The distribution pattern of the dominant species in the different communities was from clump to random in time serial from seedling to trees.The method of principal components analysis and the different methods of hierarchical cluster analysis included the nearest neighbor method , furthest neighbor method, within-groups linkage and between-groups linkage method were used to carry out numerical analysis for the community of the evergreen broad-leaved forest in Jiulianshan National Nature Reserve. The results indicated that there were a few differences among different methods, but the different classification results were consistent on the whole. The 18 forest plots were divided into 7 formations according to the important values of species in canopy layer, they were Castanopsis eyrei and Schima superba formation, Castanopsis fordii,Castanopsis fargesii,Castanopsis carlesii and Castanopsis fabric formation, Manglietia maudiae formation, Taxus mairei formation,Liquidambar formosana and Alniphyllum fortunei formation, Tsoongiodendron odorum formation and Rhododendron simiarum formation。The relationship between biodiversity and dynamics of different communities were analyzed by with different indices ofα-diversity andβ-diversity. The results showed that mostα-diversity indices in different layers of different communities were different from each other. The indices of tree layer was usually lower than that of shrub layer, and was bigger than that of herb layer, which was consistent with the general pattern in subtropical forest ecosystem in South China. According to the results of different indices ofβ-diversity, the species of the evergreen broad-leaved forest in low and high elevations were fewer than those in the middle elevation; species diversity appeared "mid-altitude bulge" and the highest species turn over rate was constantly appeared in the low elevation where was disturbed by human activity, and in high altitudes it was due to harsh conditions.The overall relatedness and inter-specific association of the main 28 tree layer species and 31 shrub layer species of the evergreen broad-leaved forest were examined by using variance ratio (VR) , x~2 test and different indices methods for 2×2 contingency table, Pearson correlation coefficient test and Spearman rank coefficient test. The results showed that the inter-specific association of the tree layer or the shrub layer species were significantly positive on the whole, but there were fewer paired species of positive association than those of negative association. According to the adaptability to the environment and the relationships between plants and environment, the main 28 canopy layer species were divided into two different ecological species groups, i. e., shade-intolerant and shade-tolerant.The niche breadths of 28 dominant species in the tree layer were investigated by using Levins index, Shannon-Wiener index and Hurlburt index. The results of different indices showed consistency and indicated that the niche breadths of Eurya japonica, Machilus microcarpa, Schima superba, Castanopsis fabric were larger than that of others because these species had strong adaptability. Based on the results of Petraitis's General Overlapping methods, there was not absolutely general overlapping among all species in the communities, and the reason was resulted from the differences among them for adapting to moisture and light. The niche overlap between dominant species in these 18 communities were calculated with Mac Arthur methods. The results showed their differences in resource utilization and species composition clearly. Generally, species with similar ecological features niche breadth tended to have greater niche overlap. But great niche overlap didn't necessarily lead to competition if their life forms were different, on the contrary, the relationships between them were very likely to be reciprocal. |
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