Characteristics And Influencing Factors Of Leaf Functional Traits Of Main Woody Plants In China

The spatial variation of plant leaf functional traits reflects the response and adaptation of plants to the growth environment,which is the result of the interaction between plants and the environment.The relationship between leaf functional traits reflects the life history strategies of plants,and then affects the coexistence of multiple species and the maintenance of biodiversity.At present,the research on the potential environmental factors that affect the variation of plant leaf functional traits mostly focuses on climate factors or single factors,and the comprehensive research combined with multiple environmental factors is relatively few,which often leads to the inability to more comprehensively clarify the variation mode of leaf functional traits,and the leading factors that affect the variation of leaf traits are not clear.In addition,woody plants play an important role in the construction of forest community structure and the composition of terrestrial ecosystem in China,but there are few studies on the leaf traits of woody plants.Therefore,this study used the method of meta-analysis to collect the data of Chinese woody plant leaf functional traits in the published literature and plant trait database,namely leaf carbon content(LC)(n = 3147),leaf nitrogen content(LN)(n = 12635),leaf phosphorus content(LP)(n = 12485),carbon nitrogen ratio(C:N)(n= 3043),carbon phosphorus ratio(C: P)(n = 2916),nitrogen phosphorus ratio(N: P)(n = 11493)and specific leaf area(SLA)(n = 2055).The data analysis mainly used R software,and the methods of variance analysis,simple linear regression analysis,standard principal axis regression analysis and relative importance analysis were used to explore the overall distribution pattern of leaf traits of woody plants;Distribution pattern and influencing factors of SLA in different functional types and genus levels of woody plants;Chemometric characteristics and influencing factors of nitrogen and phosphorus in leaves of woody plants at different functional types and genus levels;Relationship between SLA of different functional types and nitrogen and phosphorus contents in leaves of woody plants.The main results are as follows:LC,LN,LP and SLA showed an increasing trend with the increase of latitude,while C:N,C:P and N:P showed the opposite trend with the increase of latitude.With the increase of annual average temperature and annual average precipitation(MAT and MAP),LC,LN and LP increased significantly,while leaf C:N,C:P and N: P showed the opposite trend along the increase of MAT and MAP.MAT explained the spatial differentiation of most leaf traits more than the annual average precipitation.Soil factors also play an important role in shaping the spatial differentiation of leaf functional characteristics.With the increase of soil available nitrogen(AN)and soil available phosphorus(AP),leaf SLA,LC,LN and LP increased significantly,while leaf C:N,C:P and N:P were on the contrary.The contribution of Soil AN content to shaping leaf traits was greater than that of soil AP content.There were significant differences in SLA of leaves of different functional woody plants,and the main influencing factor was soil AN.SLA increased significantly with the increase of latitude,decreased significantly with the increase of MAT,and increased significantly with the increase of Soil AN and AP.The SLA of different genera varies greatly with the change of climate and soil factors,but about 1/2 genera had no significant correlation with environmental factors.LN and LP of different functional types of woody plants decreased with the increase of MAT and MAP,and increased with the increase of Soil AN and AP.Functional type is the main influencing factor of LN,MAT is the main influencing factor of LP,and AN is the main influencing factor of N:P.The N-P scaling exponent of leaves is mainly affected by MAT.The N-P power index and 2/3 of trees,shrubs,deciduous leaves and needles were not significant.There are great differences in LN and LP,N:P and N-P scaling exponent among different genus,which verifies the stoichiometry changes of LN and LP of different functional types and biological communities along the climate and soil gradient reported by predecessors.The genus level geographical pattern of N-P scaling exponent reveals the necessity of plant phylogeny and classification.Compared with the previous rough grouping of angiosperms,gymnosperms or plant functional types(i.e.functional groups),our genus level data of leaf stoichiometry can avoid the error caused by the summary data.Deciduous leaves and shrubs have higher SLA,LN and LP on the side of leaf economic spectrum(LEP),while evergreen and trees have lower SLA,LN and LP on the conservative side of LEP,which strongly supports the hypothesis of relative growth rate.The results of this study clarified the distribution law of leaf traits of Chinese woody plants at different functional type scales;The independent interpretation rate of environmental factors on leaf functional traits was determined.The environmental factors with great influence were selected,and whether the environmental factors could explain the law of vegetation differentiation was clarified.The relationship between leaf traits and traits was clarified,which provided a theoretical basis for the study of adaptation strategies of Chinese woody plants to future global changes.