Study On Functional Trait Variations And Their Correlates Of Dominant Species In Dagangshan Evergreen Broad-leaved Forest

Functional traits variation play an important role in building ecological systems and community structure,and 1s the basis and premise of plant evolution and the species coexistence.Studying functional variation at intraspecific and interspecific levels helps us to explore the mechanism for plant individuals and the communities to adapt to the environment and their response to the environmental changes,so that we can better understand the diversity of ecosystem functions and species,as well as predict the response of individual and ecosystems to global change.Taking dominant tree species in Dagang Mountain,Jiangxi Province as the research object,we analyzed variations for 12 functional traits and correlation at intraspecific and interspecific two levels,and how these function traits variation effect the growth rate.We reached the following conclusion:1.Amongst 16 subtropical species,1 1 of them are the evergreen tree species,five are deciduous trees.We measured chemical functional traits and structural functional traits from different components of plant,i.e.,leaves,twigs,trunk,and fine root.Chemical properties including s C,N,P content,and structural properties such as specifie leaf area,root length and density of xylem.The intraspecifie and interspecific variation coefficient were calculated respectively.The results showed that the intraspecific variation coefficient of specifie root length,density of xylem and the specifie leaf area were bigger than those of interspecific variation coefficient;The C content variation coefficient of leaves,twigs,and the root were the lowest in all traits variation coefficient,and in both level their values were less than 10%;The interspecific variation coefficient of P content for all component are significantly greater than intraspecific variations coefficient,and were the biggest of all the 12 traits in both interspecific and intraspecific level.2.Using the variance decomposition methods,we calculate the contribution value of life form,species and individual to the functional trait variation.The result showed that the variation of C content for all components mainly came from species,variation of N content for twig and fine root and P content for twig mainly came from interspecific and intraspecific.Leaf habit has a significant impact only on the traits associated with photosynthetic,i.e.,leaf specific area,leaf N,and leaf P.3.Using Pearson correlation test,we calculated traits correlation at different level.At the species level,C content for all components were highly correlated(p<0.001),while P content for all components has significant correlations(p<0.05),however,N content had no significant correlation for all the components.At the individual level,there was no significant correlation of elements(C,N,P)content for all components,which was different from consistent correlation for all the components at the species level.The leaf N content and twig N content,the leaf P content and twig P had significant correlation at the individual level(p<0.05).Those results suggested that at species level the elements content for all components were closely link with structure consistency,while at the individual level the elements content closely linked with functional consistency.4.On the species and individual levels,we tested the correlation of the morphological index and growth rate,and the results showed that the morphological indicators were significant associated with growth rate on the interspecific level but not in intraspecific level.The density of xylem and growth rate were significant correlation at both interspecific and intraspecific level.With diameter at breast height as the covariate,partial correlation were analyzed.The results showed that the correlation between density of xylem and the growth rate was not affected by the size of individual.Those results suggested that the correlation between the traits and growth were different at species and individual level,and to a large extent was due to the source of variation and their large differences between species and individual level.