Study On The Leaf Functional Traits Of Woody Plants And Their Relationship With Soil Nutrients In The Natural Secondary Forest Of Northern Mountains In Hebei Province

Plant leaf functional traits have important effects on ecosystem functions,which reflect plant adaptation strategies to environmental changes.The study of leaf functional traits of woody plants in natural secondary forests and their relationship with soil nutrients at different habitats were meaningful to explore the response of plants to environmental changes,to present mechanism of communities,and to clarify the structural and functional changes of natural secondary forest.Natural secondary forest is one of the main forest types in Northern mountains of Hebei province,having important ecological functions.In this study,the morphological and leaf stoichiometric functional traits of woody plants were analyzed along the slope positions of natural secondary forest in northern mountains of Hebei Province.Univariate variance(one-way ANOVA)and Pearson correlation analysis were used to investigate the intraspecific and interspecific variation and correlations between different trees at different slopes.Principal component analysis was used to explore the leaf economic spectrum among different species.And then,the correlation between leaves functional traits of woody plants and soil nutrients was analyzed by linear regression.The major results are:(1)From the study,The minor variation of plant leaf functional traits were dry matter weight(the variation was15.92%(0.29±0.05))and leaf carbon(LC)content(the variation was 7.52%(505.20±38.03)),indicating that these two indexes were relatively stable at the species level.The major variation coefficients were leaf area and leaf dry weight index among different species.The values were 69.89%(24.56±17.16)and 85.43%(0.11±0.10)respectively,which indicated the high degree of interspecific variation.The dispersion degree of leaf functional traits of the intraspecies is smaller than that of interspecific traits.Therefore,the degree of intraspecific variation of the species is smaller than that of interspecific variation.(2)The intraspecific differences of leaf functional traits of different tree species in different slope positions were different.In natural secondary forests,the leaf area(LA)and specific leaf area(SLA)decreased from downslope position to upslope position.However,the leaf thickness(LT)of Quercus mongolicaand,Tilia amurensis increased gradually.The leaf dry matter content of Betula dahurica,Betula platyphylla,Tilia mandshurica and shrub species at the upslope position was slightly higher than the downslope position.Nitrogen(LN)and carbon contents of leaves in the upslope position were lower than those in the lower slope position.There was no significant difference of leave(LC:LN)and(LN:LP)among different slope positions.Leaf morphological functional traits of different tree species at the same slope position showed there were different degrees difference.and the degree of difference of morphological functional traits of different tree species was greater than that of leaf chemical functional traits.(3)It was found that 10 pairs of leaf functional traits from different life forms showed consistent correlation at different slope positions.The correlation between leaf area and leaf thickness at the upslope position was the largest,and the correlation coefficient was 0.729(P<0.01).There was a significant positive correlation between leaf area and leaf dry weight for the trees species,and the maximum correlation coefficient was 0.935(P<0.01)for shrub species.Correlation coefficient of leaf area and leaf Kalium(LK)content showing negative correlation.The maximum correlation coefficient between leaf thickness and leaf dry weight was 0.735(P<0.05)at upslope.There was significant negative correlation between leaf dry weight and leaf kalium content in woody plants.The maximum correlation coefficient between leaf dry weight and leaf dry matter weight was 0.646(P<0.05)at down slope.The maximum correlation coefficient between leaf dry matter weight and leaf K content at upslope were-0.389(P<0.05).There was a significant negatively correlation between leaf LN and LC:LN ratio of shrub species,and the maximum correlation coefficient was-0.922(P<0.01).The leaf P content was significantly negatively correlation with LN:LP.According to the trade-off strategy among plant leaf economics spectrum,Betula platyphylla,Betula platyphylla,Acer mono,Populus davidiana and Corylus heterophylla in this study belonged to the resource conservative type.Meanwhile,Spiraea pubescens,Rhamnus rotundus,Berberis ferdinandi-coburgir could be grouped to resource acquisition plants.(4)Leaf area of trees and shrub species had positive correlation with soil total TP content.Leaf area of shrubs was significantly positively correlated with total nitrogen contents(TN).soil total phosphorus(TP)and soil organic matter(SOM),However,the trees showed an inconsistent change pattern.There was a significant positive correlation between SLA of tree species and soil total phosphorus and SOM content,but no significant correlation between different shrub species.A negative correlation between tree LT and soil nutrient elements and a positive correlation between shrub LT and soil nutrient elements was shown in this study.There was a significant positive correlation between LC:LN of tree species and TN,TP,SOM content.Plant LN,LP,LC content and soil TN,TP and SOM have different correlation,indicating that plant leaf functional traits have different selection strategies for soil nutrients.