Association Of Growth Indexes And Lignin Contents With Climate Factors In Birch(Betula Platyphylla)

Wood is the natural,renewable and sustainable resource utilized by human beings,which is irreplaceable by other materials.However,human beings have a higher demand for the high quality of wood.Forests in Northeast of China are more sensitive to climate change.Therefore,we chose birch,the pioneer tree species of the northeast forest,as the model tree,which has strong adaptability and regeneration ability,can adapt to the changes of the external environment rapidly,and is suitable for the study of climatic polymorphism.At the same time,as a broadleaf hardwood,lignin content of birch is an important parameter for the quality of wood,which is appropriate to analyze the lignin material properties.Here,we collected 481 birch trees from 96 sites across Changbai Mountain,Xiaoxing’an Mts and Daxing’an Mts,and drilled 962 cores,explored the response of birch growth and lignin to climatic factors combining dendrochronological and wood climatological methods and principles of biology,conclusions as follows:1.Large-scale climate zones have different effects on the growth of birch.With the similar height and DBH(diameter at breast height),the ages of birch trees in the cold temperate zone are significantly larger than that in the middle temperate zone.It demonstrated that the growth of birch in the cold temperate zone is slower than that in the middle temperate zone.The tree height and DBH of birch trees in the middle temperate zone were significantly positively correlated with tree age.However,for birch in cold temperate regions,there was no significant relationship between tree height and DBH and tree age.Tree height,DBH and average annual ring width of birch were positively correlated with trunk biomass,which could reflect the growth of birch to a certain extent.When the tree grows well laterally and radially,the larger the volume,the larger the biomass.2.The total lignin of birch was positively correlated with insoluble lignin,but not with soluble lignin.When the birch moisture content is higher,the soluble lignin content is higher,but not soluble lignin content and total lignin content is low.No apparent significant relationship between total lignin and growth of birch.3.The growth of birch was related to both longitude and latitude,among which height,average annual ring width,DBH,and biomass were significantly positively correlated with longitude and negatively correlated with latitude.Tree height is mainly related to precipitation,and annual precipitation can promote the radial growth of birch.DBH is mainly related to temperature,and the average temperature in summer can promote the lateral growth of birch;The average annual ring width is related to both temperature and precipitation,and its growth is inhibited by isothermal and monthly precipitation difference;Trunk biomass was related to both precipitation and temperature,and was mainly negatively correlated with monthly temperature difference and monthly precipitation difference,which was affected by some extreme temperature events and extreme precipitation events.4.The total lignin of birch has nothing to do with longitude and latitude,but is related to altitude.At higher altitudes,the total lignin content of birch will increase.Soluble lignin was more affected by temperature than precipitation,the temperature difference is not conducive to the synthesis of soluble lignin.Insoluble lignin was more affected by precipitation,the wettest month precipitation is not conducive to the synthesis of insoluble lignin.Overall,some extreme temperature difference events would inhibit lignin accumulation,while precipitation in the wettest month would promote lignin accumulation.This study provides new evidence for tree growth,wood properties responding to climate changes,tree breeding adapting to targeted local stands.At the same time,it provides a basis for further research on the molecular mechanism of tree growth and wood properties in response to climate change.