Studies On Stand Structure And Species Diversity Of Evergreen Broad-leaved Forests In Yanping District, Nanping, Fujian

Stand structure and species diversity are two important indicators of biological diversity. Stand structure is the basis and performance of stand features, and species diversity not only is the center of biodiversity, but also the most important structure and functional unit. Mastering the resource status of species diversity, analyzing the features of stand structure and species diversity, and carrying on reasonable operating and scientific management play an important part in realizing sustainable forest management. The research place is Yanping District, Nanping City, Fujian Province. In this region the Broad-leaved species mainly included Castanopsis, Schima superba,Cyclobalanopsis glauca, Castanopsis carlesii, Alniphyllum fortunei, Phoebe zhennan, Castanopsis kawakamii, Cryptocaryeae, Castanopsis fordii, Loropetalum chinensis,and so on. These species had the representation of the mid-subtropical evergreen broad-leaved forest. The stand structure and species diversity characteristics of evergreen broad-leaved forest in the region were analyzed according to floristic characters, ecology niche, diameter structure,spatial patterns, species diversity. The specific conclusions are as follows:1. The evergreen broad-leaved forests were rich in flora species, and had the ancient origin and obvious mid-subtropical properties.The evergreen broad-leaved forests of Mangdang Mountain in Yanping, Fujian had a higher richness of species diversity, including 185 families,719 genus,1 575 species (contain 77 variant,6 subspecies,2 cultivated varieties,1 variant); Chinese endemic genera (19 genus) also occupied a certain proportion, about 6.79% of total; Rare and endangered species were rich, and there were 21 rare and endangered species, 4 species of national Gradeâ… rare and endangered plants and 17 species of national Gradeâ…¡rare and endangered plants included,and there were 23 kinds of provincial-level key protected plants of Fujian Province. The single genus and small genus were rich,and single species family and depauperate family had large proportion. Meanwhile, there were a considerable number of Magnoliaceae plants along with many ancient plants whose evolution status were similar to some Magnoliaceae plants.The various components of class and critical families relatively completed, which was in line with the Chinese district flora characteristics. The proportion of temperate element was large,which had a obvious mid-subtropical character. 2. Ecological niche similarity of the main tree species of the evergreen broad-leaved forests had a higher proportion, but a small ecological niche overlap.Ecological niche similarity of the main tree species of evergreen broad-leaved forests in Yanping, Fujian had a higher proportion,and there were 17 pairs whose ecological niche similarity ratio were more than 0.9 among the top 10 main tree species, and when niche ecological similarity ratio were more than 0.8 there were 38 pairs, and when niche ecological similarity ratio were more than 0.6 there were 44 pairs. However, ecological niche overlap values were very small, mainly because the study range in this paper were a larger geographical areas, and regarded a district (county) as a larger plot. In a larger geographical scope, many species still existed a degree of niche ecological overlap. It showed that it was an obvious trend for various species groups to share the same resources,which indicated that the subtropical evergreen broad-leaved forest community in Yanping District was relatively stable.3. The diameter class structure of the main species of the evergreen broad-leaved forests is diverse.The diameter class structure diagram types of main tree species of evergreen broad-leaved forests in Yanping District, Nanping, Fujian could be divided into four categories, namely the L-type, inverted J type, single-peak type, multi-peak type. At the same time, abundance- diameter class distribution curve types also could be divided into four categories; The first category was logarithmic equations with the highest correlation coefficient, while the correlation coefficients of power function equation and exponential equation were also relatively high; The second kind was power function equation with the highest correlation coefficient, simultaneously the correlation coefficients of index and logarithm equation were also high; The third category was logarithmic equations with the highest correlation coefficient, meanwhile the correlation coefficients of index equation was also relatively high, but it was not suitable to fit power function equation; The fourth category were those that be not suitable for fitting to any equation because of a number of ups and downs existed in the diameter distributions.4. The spatial pattern of main tree species of the evergreen broad-leaved forests was cluster distribution.The spatial pattern of top 10 abundance tree species of evergreen broad-leaved forest communities in Yanping District, Nanping, Fujian were cluster distribution. The decreasing order of cluster degree was Castanopsis kawakamii, Cyclobalanopsis glauca, Loropetalum chinensis, Alniphyllum fortunei, Phoebe zhennan, Castanopsis carlesii, Schima superba, Castanopsis;Castanopsis, Cryptocaryeae, Castanopsis fordii. Castanopsis took on cluster distribution at the general,the southern slope and the northern slope , and the decreasing order of cluster degree was the general,the southern slope,and the northern slope. The cluster degree from hing to low at three different developmental stages was the middle-diameter timber stage, the big-diameter timber stage, and the small-diameter timber stage. The reason was mainly that the Castanopsis in the individual samples during 18 samples belonged to the big-diameter timbers or middle-diameter timbers,and even there were no small-diameter timbers.5. The evergreen broad-leaved forests took on the " reversal J type " in the height and diameter class structure, and their abundance and richness index existed positive correlation,also had a high species diversity .With the increase of tree height or the diameter class, the abundance,tree number and tree species of evergreen broad-leaved forests in Yanping District, Nanping, Fujian showed the distribution of"reversal J type"in the whole, the southern and northern slopes. There was the obvious positive correlation between the tree species richness and density of trees,that was to say,in the evergreen broad-leaved forests of Yanping District, the larger tree density was, the larger number of tree species was. Species number and Marglef index were the highest in general, and the southern slopes'were the second, northern slopes'was the lowest; The homogeneity index was the highest in the northern slopes,the second in the general's and the southern slopes'was the lowest. But the shannon-wiener index and Simpson index were all similar in the general, southern slopes and northern slopes. The research ground had quite plentiful species and high index diversity.Accroding to the conclusions above, brought out suggestions on the diversity protection of the evergreen broad-leaved forests in Yanping District ,as follows:(1) Reinforce publicity in education, and carry out policies vigorously to protect plant diversity and ecological protection.(2) Reinforce the construction and management of nature reserve .(3) Reduce the human actions of undermine for ecology .(4) Reinforce the input funds in the construction of specise diversity .(5) Reinforce the rare and extinct specises'local and migrating protection .(6) Reinforce scientific researches in specises diversity.