Study On Geographical Variation Of Functional Traits And Content Of Carbon,nitrogen And Phosphorus In The Twig Of Davidia Involucrata Baill.

The survival of plants is closely related to their external environment.Dove tree(Davidia involucrata Baill.)is a rare and endangered plant under national protection.It is a Cenozoic tertiary relic plant endemic to China.In order to further reveal the environment on the functional traits and the influence of nutrient element content of dove tree,this study with annual twigs of dove tree as the research object,from the level of stems,leaves and flowers the growth of the relationship between the traits,growth relationships between traits and the contents of carbon,nitrogen and phosphorus in nutrient components and reproductive components,etc.,which the variation of dove tree at three different altitude and three different latitudes was compared and analyzed.The main results of this study are as follows:1.Altitude and latitude had significant effects on the traits of twigs.At the altitude gradient,stem diameter,twig mass,large bract length,small bract length,large bract width,small bract width,individual inflorescence axis length,large bract area,small bract area,total bract area of individuals flower,total bract area,large bract mass,small bract mass,total bract mass of individual flower,individual inflorescence axis mass,total mass of flower,total inflorescence axis mass,total flower mass and reproductive allocation decreased with elevation.While leaf length,total leaf area,total lamina mass and total leaf mass increase with elevation.In the latitude gradient,stem diameter,stem mass,stem length,twig mass,leaf number,individual inflorescence axis diameter and total mass of flower decrease as the latitude increases.While leaf length,leaf width,individual leaf area,individual leaf mass,large bract length,large bract mass and total bract mass of individual flowers increase with the increase of latitude.The other traits have no gradient change with altitude and latitude.2.Altitude and latitude had significant effects on the relationship between the traits of twigs.In the altitude gradient,total lamina mass and stem mass,total lamina mass and total petiole mass,total bract area of individual flower and total bract mass of individual flower,small bract area and large bract area,small bract mass and large bract mass showed significant positive correlation.3.Altitude and latitude had significant effects on the content of carbon,nitrogen and phosphorus of twigs.As the elevation increases,the temperature decreases and the precipitation increases,lamina N has a significant positive correlation with altitude.However,as the latitude increases,the temperature decreases and the precipitation decreases,stem C:N has a significant negative correlation with the latitude.Lamina C and lamina C:N were significantly positively correlated with latitude.Bract C:N were significantly positively correlated with latitude.However,no matter in elevation gradient or latitude gradient,the C contents of stemes,leaves and bracts were similar and all had higher N and P.However,the content of N in bracts varies dynamically,and the growth of dove stemes and leaves is mainly restricted by N.In summary,the functional traits,the relationship between traits and the contents of C,N and P in the twigs of dove tree were significantly affected by the changes of altitude and latitude.In the high altitude environment,the dove tree is more exposed to low temperature,heavy precipitation and strong wind than in the low altitude environment,while in the high latitude environment,the dove tree is more exposed to low temperature and drought than in the low latitude environment.Such geographical differences may be the reason for the formation of growth trade-off in the evolutionary process of dove tree,so as to alleviate the environmental stress.