Research For Leaf,Stem And Root Functional Traits For Common Tree Species In Subtropical Evergreen Broad-leaved Forest

Plant functional traits that including plant morphology, physiological or phonological features are the results of the interaction between plant and ecosystem, and the service of the ecosystem is also effected by them. In addition, plant functional traits act as an intermediary connecting the environment, plant individual and the structure, process and function of ecosystem together and provide a means to study the response or adaption of plant to the habitat. It can’t be more important to understand the plant functional traits when it comes to forest ecosystem management. A mass of researches have been conducted that aimed to explored the photosystem of plants, whereas few study that correlated to the traits of stem and root, especially that the correlation of different modular system in a certain species, has been carried out. In our study,11 architectural traits and 16 functional traits of 16 main tree species were selected in subtropical evergreen broad-leaved forest in Dagangshan, Jiangxi. The main results were found as follows:1. Sixteen main tree species including eleven evergreen tree species and five deciduous tree species were selected in our experiment. The architectural traits such as the tree height, diameter at breast height, canopy and the successional status were recorded, and the functional traits such as leaf traits (specific leaf area, tissue density, contents of carbon, nitrogen and phosphorous in leaves), stem traits (twig tissue density, fresh and dried wood density, contents of carbon, nitrogen and phosphorous in twigs) and root traits (thick root density, contents of carbon, nitrogen and phosphorous in fine roots). All the contents of carbon, nitrogen and phosphorous belonging to chemical traits while the rest are structural traits.2. The results of the differences of all functional traits in evergreen tree species and deciduous tree species analyzed by ANOVA showed that the specific leaf area and the leaf nitrogen content displayed a notably difference between evergreen tree species and deciduous tree species, whereas the difference in rest traits was not significant. Our results indicated that the variance of evergreen tree species and deciduous tree species could be explained by the variance of photosynthetic capacity, for instance, the better photo synthetic capacity in deciduous tree species than in evergreen tree species could cover the shortage of its leaf lifespan.3. The 15 structural and chemical traits (no fresh wood density) of the 16 main tree species are analyzed with using multiple T test and Pearson correlation test. In structural traits, there is no significant correlation between specific leaf area and specific root length whereas differences of the tissue density among the three modules are significant and the correlation between stem and root tissue density is stronger. In chemical traits, the carbon contents of the three modules don’t vary significantly and their pairwise correlations are extremely strong, meanwhile, leaf nitrogen content is significantly higher and the correlation exists between leaf and root nitrogen concentrations. Besides, twig phosphorous content is the highest and the phosphorus contents of the three modules are positively related. Therefore, according to the results of structure traits, the functions of stem and root are more closely related. While according to the chemical traits, leaf and root are more closely related, if judge from the overall perspectives, the functional traits of the three components are all coupled and they are proxies to the ecological strategies to adapt to the environment.4. Principal component analysis (PCA) was used to analyze the architectural traits and component traits, respectively, and the results of the two kinds traits are not the same. For the architectural traits indicators, the first principal component represents the plant’s ability to capture light, the variance contribution rate is 60.21%; the second principal component represents the plant’s ability to intercept light, the variance contribution rate is 17.06%, both for 77.27%. The result can explain the ability to compete for light of the tree species in the forest community. For the component traits indicators, the first principal component represents the resource acquisition and processing capacity of the plant, the variance contribution rate is 42.76%; the second principal component represents the plant’s ability to build own, the variance contribution rate is 19.90%, both for 62.66%. The result can explain the plant ecological strategy what is growing last or living long.