Study On The Functional Traits Of Common Woody Plants In Chongqing Mountain Park

Plant functional traits are a set of core plant characteristics that arise during the growth and development of plants to adapt to environmental changes.The diversity of plant functional types and functional groups is an important component of plant diversity.In urban areas,the study of plant functional traits can help to understand the distribution characteristics of urban plant diversity and its ecological strategies for adapting to the environment,which is important for the protection and conservation of urban plant diversity and the construction of urban ecological environment.In this paper,48 common woody plant species in Zhaomushan Forest Park,Hong’en Temple Forest Park and Pingdingshan Park in the main urban area of Chongqing were studied.16 functional traits,including plant height,stem cross-sectional area,stem volume,specific leaf area,whole leaf dry weight,fruit dry weight,pericarp dry weight and seed dry weight,were selected from the functional traits of plant height and annual branchlets.Pearson correlation analysis was used to analyze the correlation coefficients among the traits;the frequency distribution was used to analyze the overall characteristics and range of variation of the functional traits of woody plants,and the 48 woody plants were further clustered according to the differences in the functional traits;the differences in the functional traits of woody plants of different growth types and the differences in seed size of woody plants of different fruit types and plant heights were compared;the differences in seed size of woody plants of different environments were compared.We also compared the functional traits of four widely distributed species,namely Huangge tree,Guanyang tree,Jinfushan viburnum and Haitian tree,and explored the differences in functional traits of the same species under different environmental conditions.The main findings are as follows:(1)There was a significant correlation among the functional traits of woody plants.The specific leaf area was negatively correlated with plant height and decreased with increasing plant height;leaf dry weight was positively correlated with plant height and increased with increasing plant height;leaf dry weight,fruit dry weight and seed dry weight were positively correlated with stem dry weight and stem cross-sectional area,respectively,indicating that the biomass on the branches increased with the thickening of the branches.The correlation among functional traits indicate that the traits are synergistic and co-evolving among woody plants in the process of adapting to environmental changes,and this mutually coordinated relationship determines the ecological strategies of plants to adapt to the environment.(2)The interspecific variation of each functional trait in woody plants was large,and there were different degrees of coefficients of variation among the functional traits,with an average coefficient of variation of 150%.Among them,the coefficients of variation were >200% for fruit stalk dry weight,pericarp dry weight and whole leaf area,ranging from 150% to 200% for stem volume,stem dry weight,whole leaf dry weight and fruit dry weight,ranging from 100% to 150% for seed dry weight,single leaf area and single leaf dry weight,and the smallest coefficients of variation were for plant height,specific leaf area and specific leaf dry weight,with coefficients of variation <100%.This reflects that fruit traits,leaf traits and stem traits of urban woody plants respond strongly to interspecific competition for exclusion,plant height and seed dry weight respond less strongly to interplant competition,and specific leaf area and seed dry weight can also reflect to some extent the response of woody plants in mountainous urban parks to disturbance.(3)48 species of woody plants were classified into 4 functional types by cluster analysis.Functional type I contains 20 species of plants represented by abacus(Loropetalum chinense)and plum(Prunus salicina),whose common characteristics are the lowest plant height,the smallest seed dry weight and the largest specific leaf area,which are more productive and more adaptable to the environment..Functional type II has a larger specific leaf area,smaller seed dry weight and plant height.It contains 12 species of plants,such as Sloanea sinensis,Distylium racemosum,etc.These plants have a high growth rate,high survival rate,and are highly disturbed by the environment.Functional type III is dominated by 13 species of large trees such as pecan(Juglans regia),neem(Melia azedarach),and soapberry(Gleditsia sinensis),with common characteristics of larger plant height and seed dry weight and smaller specific leaf area,which are more resistant and competitive to disturbance and have higher adaptability and tolerance to adverse environments.Functional type IV includes three species of tall trees represented by sycamore(Firmiana simplex)with the highest seed dry weight,highest plant height,and smallest specific leaf area.This functional type of plant has low specific leaf area,long leaf life,and is more resilient to adverse environments.(4)The functional traits of different growth types of woody plants were significantly different.The plant height,specific leaf area,stem dry weight,fruit dry weight,and seed dry weight of deciduous plants were greater than those of evergreen plants,and the specific leaf dry weight of evergreen plants was greater than that of deciduous plants,except for the specific leaf area,which was greater for shrubs than trees,all other functional traits were smaller for shrubs than for trees.Different growth types have different competitive ability and access to resources,resulting in large differences in functional traits among plants of different growth types,reflecting the different adaptation strategies of different growth types to the environment.(5)The seed weight of different fruit types of woody plants varied significantly,with drupes and nuts having the largest seed weight,and berries and capsules having relatively lighter seed weight,as drupes and nuts contain only one seed and their single seed dry weight is large,while berries and capsules produce a large number of seeds and their single seed dry weight is lighter.There are also large differences in the 100-seed weight of woody plants of different plant heights,with larger trees having a larger 100-seed weight than smaller trees and shrubs.The larger the tree,the more competitive it is and the larger the seeds it produces to nurture offspring.(6)Four widely distributed plants functional traits differed significantly among the three parks.Plant height of yellow kudzu,leaf traits and stem traits of Gymnema sylvestre and Jinfuoshan podophyllum,and fruit traits of Hellebore differed significantly among the three parks.Environmental conditions such as topography,slope,slope orientation,and elevation differed among the parks in the mountainous cities,reflecting the different adaptation strategies of the same species to different environments.