色季拉山不同径级急尖长苞冷杉树皮功能性状变异及权衡OA

To explore the variation characteristics and trade-off relationships of bark functional traits of Abies georgei var.smithii along diameter classes,this study took A.georgei var.smithii in Sejila Mountain as the research object.Samples were se-lected from three diameter at breast height(D)classes:D≤30 cm,30 cm＜D＜60 cm,and D≥60 cm.Eight functional traits including bark thickness,water content,density,and element mass fraction were determined.Statistical analysis was used to test the differences in bark functional traits among different diameter classes,and principal component analysis(PCA)combined with correlation analysis was applied to explore the synergistic relationships and trade-off patterns of bark functional traits.The results showed that:(1)Bark functional traits exhibited significant variation across different diame-ter classes.Total bark thickness increased with the rise in diameter class,rising from approximately 6 mm to 30 mm,while bark water content,total nitrogen mass fraction and total phosphorus mass fraction gradually decreased,declining from a-bout 53%,4.8 g/kg and 0.6 g/kg to 36%,3.3 g/kg and 0.4 g/kg,respectively.(2)Obvious synergistic and trade-off relationships existed among traits.Bark water content was extremely significantly negatively correlated with outer bark thickness and total bark thickness,and extremely significantly positively correlated with total nitrogen and total phosphorus mass fractions of bark.Outer bark thickness was extremely significantly positively correlated with total bark thickness,and extremely significantly negatively correlated with bark total nitrogen and total phosphorus mass fractions.Bark total nitrogen mass fraction had an extremely significantly positive correlation with total phosphorus mass fraction.(3)At different diam-eter class stages,key traits exerted distinct effects on tree growth.Thickness-related traits positively predicted tree height and diameter at breast height,whereas water content and total nitrogen mass fraction showed negative effects.(4)Princi-pal component analysis revealed that the first three principal components explained more than 69%of the total variation.With the increase of diameter class,the dominant effect of thickness traits was enhanced,while the synergy between water content and nutrient traits weakened,further indicating the differences in resource allocation and trade-off strategies of functional traits among different diameter classes.The variation pattern and trade-off structure of bark traits in A.georgei var.smithii reflect its functional adaptation strategies in response to environmental changes and resource availability across growth stages.