Variations Of Leaf And Fine Root Functional Traits Of 15 Woody Species In Two Habitats

The relationship between plants and environment has traditionally been a core problem in forestry and ecology.Leaf and fine root are important vegetative organs of plants aboveground and belowground.The relationship between leaf,root and environment has been widely concerned.Previous studies have demonstrated that the structural and functional characteristics of leaves vary with environmental changes,and fine roots also respond accordingly.However,the underlying mechanism of the variation has not yet been well understood.In addition,it is not clear how the leaf and root traits are correlated,and how the correlation changes with the environment.In this study,we compared the leaf and fine root morphological,anatomical and chemical traits of 15 common woody plants in Maoershan natural secondary forest of Heilongjiang Province and Nenjiang sandy land of Daqing.The main purpose of this study was to reveal the variation of the structure and function of leaves and fine roots in different habitats,to identify which functional traits play an important role in correlation between aboveground and belowground,and to clarify the influence of habitat changes on the correlation of functional traits.The results showed that:(1)The leaf functional traits of woody species varied markedly across the two habitats.In terms of morphological traits,most species on sand land generally had smaller specific leaf area and larger leaf thickness.In relation to leaf anatomical traits,the species on sand land generally had thicker upper and lower epidermis,palisade and spongy mesophyll tissue,higher ratio of palisade to spongy mesophyll tissue and higher vein and stomata density.Similarly,we observed a higher concentration 11.7%of leaf nitrogen in secondary forest relative to those species on sand land,and no significant differences were observed in leaf carbon concentration between the two habitats.Therefore,the higher C/N ratio 17.7%was observed on sand land relative to that of the secondary forest.We also found a significant correlation between leaves morphological and anatomical traits,and the closer correlation was observed on sandy habitat,but the chemical traits were relatively independent.Furthermore,we found that the leaf morphological traits had the highest plasticity and were most sensitive to environmental changes.(2)The root functional traits of woody species altered significantly by the two habitats.Species on the sand land generally had the conservative survival strategy of coarsening diameter,decreasing specific root length and increasing tissue density.Species on sand land generally had thicker cortical thickness and smaller average conduit diameter.There were significant differences between the two habitats in the diameter of the stele and the maximum vessel.Most species on the sand land(i.e.,67%)had higher ratio of cortical thickness to stele radius than the secondary forest.The fine root diameter(<2mm)and tissue density has significantly increased across the branch order(1-3 order root),while the specific root length significantly decreased.However,the nitrogen concentration of fine roots significantly decreased,while the carbon concentration increased across the branch order(1-3th order root)in both habitats.In the secondary forest,67%of the tree species had higher root nitrogen concentration,while the fine root carbon concentration remained stable across the habitats.Root tip morphology and anatomical traits of woody species were closely related,while the chemical traits were relatively independent.Among all traits,the higher plasticity of morphological traits,and the least plasticity of chemical traits was observed.(3)Conduit density of the first order roots was found to be positively correlated to stomata density in both habitats,and reached a significant level in sandy habitat.While most of the leaf and root functional traits have no correlation,indicates that the leaf and root functional traits were relatively independent,and their strategies of resource acquisition and utilization were different.Hence,we concluded that the leaf and fine root traits of woody species can respond to environmental changes from multiple dimensions,and the morphological traits are the m ost sensitive.Except for hydraulic traits,there is no correlation between leaf and fine root traits of woody plants,indicating the relative independence of resource acquirement and utilization between leaf and root functional traits.