| Non-structural carbohydrates are important photosynthetic products involved in plant metabolic processes.The storage and distribution of NSC can reflect the balance of carbon metabolism in plants to a certain extent,and NSC plays an important role in maintaining plant osmotic regulation,hydraulic transmission,growth and development,as well as the carbon supply and demand relationship between years,seasons and organs of buffer trees.At present,there are few studies on the interspecific difference of NSC concentration of different tree species in temperate forest and its relationship with tree growth.In this study,the NSC concentrations of trunk tissues and crowns of 32 tree species in typical temperate coniferous and broad-leaved mixed forest in Muling yew National Nature Reserve were measured,the area weighted concentrations of NSC in trunk tissues were calculated,and the differences of NSC concentration in various organs of different wood porous tree species and the relationship between NSC concentration and radial growth were analyzed.The main results were below:(1)The concentration of NSC in leaves and branches varied greatly among species.Organs,wood porosity and their interaction significantly affected the concentration of NSC.The concentration ratio of soluble sugar and starch in leaves was over 3,which was significantly higher than that in branches,indicating that leaves had high physiological activity.The concentration of soluble sugar and total NSC in leaves were non-porous wood > diffuseporous wood > ring-porous wood,while the concentration of starch in branch showed the opposite trend,indicating that there were differences in the functional differentiation of leaves and branches of different wood species.The correlation analysis of NSC concentration between leaf and branch showed that the correlation of non-porous wood was the best,but there are no significant correlation in ring-porous wood.These results showed that there are differences in the storage and distribution strategies of NSC among different tree species with different wood porosity.(2)The concentrations of NSC in the three tissues of trunk had greatly difference,the concentration of soluble sugars(7.52%)and starch(4.78%)in bark was the highest,sapwood comed second,and heartwood was the lowest.The interspecific variation of concentrations of soluble sugars,starch,total NSC and sugar/starch ratio in the three tissues were high,with the lowest coefficient of variation of 37%(total NSC concentration in bark)and the highest of101%(starch concentration in heartwood).Tissue,species and their interactions significantly affected trunk NSC concentration.The concentrations of soluble sugar,starch and total NSC decreased with the increasing radial depth,only the concentration of NSC in heartwood in nonporous wood was higher than sapwood.The concentration of soluble sugar in bark in nonporous wood was significantly higher than others,but the concentration of starch and total NSC in sapwood showed a trend that was ring-porous wood was higher than diffuse-porous wood,and non-porous wood showed the lowest concentration.The change trend is the same as that of total NSC concentration in branches,indicating that the ability of xylem to store NSC increases with the evolution of trees.The ratio of soluble sugars,starch and total NSC concentrations in sapwood to in heartwood were about one for non-porous wood species,which were significantly lower than those for diffuse-porous and ring-porous wood species,and the correlation of the starch concentration between sapwood and heartwood of non-porous wood was closer than that of the other two wood-porous types,indicating that the functional differentiation between sapwood and heartwood was clearer for angiosperms than for gymnosperms.Although there were significant differences in soluble sugar concentrations in different tissues of tree trunks with different wood porosity,there was no significant difference in the area weighted concentration of soluble sugar in the trunk,indicating that the differences in biomass and soluble sugar concentration of different tissues should be considered when estimating the NSC content of the trunk.The change trend of stem starch area weighted concentration was ring-porous wood > diffuse-porous wood > non-porous wood,and there were significant differences among different wood properties,indicating that with the evolution of trees,the NSC reserves in the trunk gradually increase,which was conducive to improving the stress resistance of trees.(3)There were no significant differences of radial growth in different wood porosity tree species in recent ten years,this meant that the environmental impact in a short time scale did not make the growth of different wood species different.The results of correlation analysis between radial growth parameters and NSC concentration in various organs of trees showed,the radial growth of non-porous wood was significantly negatively correlated with leaf starch concentration,and the radial growth of trunk of diffuse-porous wood and ring-porous wood was significantly negatively correlated with the starch concentration of branches and sapwood,indicating that NSC concentration can be used to predict the radial growth of trees.There were differences in the relationship between the radial growth of trunk and the concentration of NSC in various organs of different wood porous tree species,indicating that the functions of various organs have differentiated to varying degrees in the process of tree evolution.In this study,We found that wood porosity affected the trunk NSC storage strategy of temperate tree species.In the future,it is necessary to distinguish trunk tissue in order to study the whole tree NSC and the physiological and ecological function of trees.In the study area,the environmental changes in a short time scale did not make the radial growth of different wood porous species different.There were differences in radial growth and NSC concentration in various organs of different wood porous species,and there were differences in functional differentiation of various organs of different wood porous species.Our results provide support for exploring the characteristics of NSC storage and distribution of temperate trees and their relationship with tree species evolution,and provide reference for the mechanism interpretation of predicting tree growth under the background of climate change. |
PDF Full Text Request