Trait Gradient Analysis for Evergreen and Deciduous Species in a Subtropical Forest

Abstract

Leaf habits (e.g., evergreen or deciduous) can reflect strategies of species adapting to varied environmental conditions. However, how species with different leaf habits coexist within a plant community is still poorly understood. Trait gradient analysis is a new approach to partition plant functional trait variations into alpha (within-community) and beta (among-community) components to quantify the effects of environmental filtering and biotic competition on community assembly. Here, on the basis of establishing forty-eight forest dynamic plots in a subtropical evergreen and deciduous broadleaved mixed forest in central China and measuring of seven functional traits, we compared the trait variation patterns and influencing factors of evergreen and deciduous species by using the trait gradient analysis method. The results showed that there were significant differences between functional traits for evergreen and deciduous species. Alpha trait components consistently varied more widely than beta components. The correlation between species trait mean and the alpha of each trait was highly significant, but there was no significant correlation between beta and alpha trait values. There were relatively weak or nonexistent significant correlations among species mean trait values and alpha trait values of different functional traits. However, the beta trait value showed high and significant correlations in both evergreen and deciduous species. Our results indicated that evergreen and deciduous species adopt similar adaptation strategies (beta component) in the context of environmental change in the community. However, the species initially came to coexist via the ecological positioning of traits (alpha component), which helped reduce competition so individuals could obtain more resources.