Leaf Functional Traits And Their Relationships With Environmental Factors In Beishan Mountain Of Jinhua,Zhejiang Province

As an important part of plant functional traits,leaf functional traits are the bridge between plant physiological adaptation and environment,reflecting plants' ability to acquire and utilize resources and environment,and truly reflect the environmental changes and impact of resource competition on species in the process of community construction.The study on the relationship between functional traits of plant leaves,their inter-and intra-specific variations and response mechanism to environmental factors will help understand the mechanism of plant response to environmental changes and its ecological adaptation strategy,and further the biodiversity and function of ecosystem.In addition,it is a common approach in current plant trait research that classifying plants into different growth forms to statistically analyze features of plant functional traits in various vegetation types.Different classifications of growth form,however,may lead to statistical bias of plant trait values,and such bias has not been further evaluated.Here,as a specific topic,we investigate how different classifications of growth form influence the calculation of plant functional traits.This paper selects six representative vegetation types,including coniferous forest,mixed needleleaf and broadleaf forest,evergreen broad-leaved forest,mixed evergreen and deciduous broad-leaved forest,secondary scrub and mountain primary shrubs in Beishan Mountain of Jinhua,Zhejiang Province.We constructed 24 fixed plots and collected 42 dominant and common species of woody plants as the research object.Some leaf morphological traits(leaf area,leaf thickness,leaf water content,specific leaf area,and leaf dry-matter content)and ecological stoichiometric traits(leaf carbon content,leaf nitrogen content and leaf phosphorus content,and leaf potassium content),as well as soil factors(including pH value,soil organic matter,total nitrogen,total phosphorus,and total potassium content)and terrain factors(elevation,slope,and aspect)were measured.Based on these trait data and environmental factors,this paper analyzed the characteristics of leaf functional traits of woody plants and its inter-and intra-specific variations,relationships among different leaf functional traits,and those between traits and environmental factors.In addition,we classified the growth form of 35 dominant woody plants into three schemes according to the Flora of China and actual situation in filed investigation: the classification 1,traditional tree and shrub described in the floras;classification 2,trees,small trees and shrubs based on height and diameter in breast height;and classification 3,trees and shrubs of tree layer and shrub layer according to height only.Statistical bias of plant leaf and twig traits under three classifications of growth form was analyzed and compared.The results are as follows:1)Twelve leaf traits varied in various extents.Leaf area had the highest variation and leaf carbon content had the lowest.Compared with leaf traits in region with the same latitude as in Beishan Mountain,there was a series of functional trait combinations including thick leaf thickness(LT),small leaf area and specific leaf area,large leaf dry matter content and leaf nitrogen content,and high nitrogen to phosphorus ratio,to adapt to environmental changes in Beishan Mountain,Jinhua.2)Different plant leaf traits had not only close correlations,but also differences in their interspecific and intraspecific variations.At the intraspecific level,the correlations of most leaf traits among different growth form,life form and vegetation types were consistent,but there were significant differences in some traits.The explanation rate of species and life form to most leaf traits variation was higher than that of the influence of growth form and vegetation types alone,as well as of pairwise and third-order interaction.3)Variation partitioning results showed that eight environmental factors explained 30.94% of leaf functional trait variation,among which soil factors could explain 22.13% of leaf functional trait variation and terrain factors could explain 6.91%.The joint interpretation of terrain and soil factors on leaf functional trait variation was only 2.69%,while the unexplainable part was 69.06%,indicating that the interaction between plants and the influence of random factors were higher than that of environmental factors in Beishan Mountain,Jinhua.Stepwise regression analysis further showed that soil pH was the dominant environmental factor of leaf area,leaf carbon content,nitrogen content,phosphorus content and leaf carbon to nitrogen ratio.The dominant environmental factors of leaf thickness,specific leaf area,leaf dry matter content and leaf potassium content were soil total nitrogen,while leaf water content,leaf tissue density and leaf nitrogen to potassium ratio were mainly affected by soil total phosphorus.4)Compared with the classification 1,when not considering small trees in the classification 2,classification 2 has a higher influence on twig and leaf traits of trees than classification 3,while the influence on twig and leaf traits of shrubs is lower than classification 3.However,there is no significant difference in general of tree and shrub traits in different growth classification schemes.Compared with small trees in classification 2,traits of small trees are significantly different to those of trees and shrubs among different growth form schemes and even within the classification 2.