A Study On The Coexistence Mechanism Of Betula Albosinensis Forest Species Based On The Regeneration Niche And Seedling Functional Traits In Qinling Mountains

Understanding the coexistence mechanism of tree species has always been a central issue in forest ecology,which is of great significance to the protection and management of forest ecosystems.Although ecologists often assume that trait differences between species promote species coexistence,few studies have linked functional traits to niche differences.Combining functional traits with niche differences of species can establish the corresponding relationship between functional traits and specific environment at the species level.On the one hand,it can provide a mechanism explanation for species coexistence in communities,and at the same time,it can also help predicting the species diversity in different environments based on functional traits.In this study,the microhabitat structure and functional characteristics of seedlings of main canopy tree species in different communities of Betula albosinensis forest in Qinling Mountains were investigated.Based on these data,we analyzed the difference of regeneration niche and functional traits among seedlings of different tree species,the relationship between regeneration niche and functional traits,and the difference of functional traits among different life cycle stages.The results will help us to better understand the construction process and species coexistence mechanism of forest communities in warm temperate zone,and also provide theoretical basis for species diversity conservation and restoration and reconstruction of similar communities.The main findings of this study are as follows:(1)Among the three types of Betula albosinensis forest communities investigated,there were significant differences in the regeneration microhabitats of seedlings of coexisting tree species,suggesting that the regeneration niche differences play an important role in promoting the coexistence of community species.In addition,this study also found that light is the main factor determining the microhabitate where tree seedling establish.(2)There were obvious differences in functional traits of seedlings of coexisting tree species in different communities of B.albosinensis,and the functional traits of seedlings of different tree species showed obvious adaptability to the their established microhabitats,suggesting the species-specific adaptation to understory different microhabitats.In addition,some traits showed significant differences among the different life-history stages,while others keeped constant,and the changes of traits among the different life-history stages varied with species.This indicates that the functional traits of trees do not remain unchanged with the life-history,and change with the development of individuals and the changes of their surroundings.(3)The leaf traits and seed size of seedlings were found significantly correlated with the microhabitat variables,and they all reflect the niche differentiation of regeneration along the light gradient under the forest,suggesting that leaf and seed traits can predict most of the microhabitat characteristics of seedlings establishment.