Interannual Dynamics And Influencing Factors On Survival Of Woody Seedling In The Mid-Montane Moist Evergreen Broad-Leaved Forests In Gaoligong Mountain

The coexistence mechanism of species is one of the key issues in community ecology research.The neighborhood effect is used to study and explain the mechanism of species coexistence.The neighborhood effect is the interaction between plants within a certain time and space,mainly including density dependence,competition,and mutualism.The survival of seedlings is closely related to community dynamics.The interactions between neighbors,environmental factors,and functional traits of target individuals will affect the survival of seedlings.The 100 2m×2m seedling plots are in the 4-hectare dynamic plot of the middle mountain wet evergreen broad-leaved forest in Gaoligong Mountain as a platform.Using the three seedling censuses data from 2020 to 2022,combined with functional trait data,soil physical and chemical property data,light availability,and terrain factor data,the generalized linear mixed model is used to explore the impact of environmental factors,neighbor density,and functional traits on seedling survival,to analyze the ecological mechanisms driving community dynamics.The experimental results showed that:(1)A total of 986 seedlings were recorded in the investigation,belonging to 56 species,45 genera,and 24 families.The distribution of the number of species and seedlings in the sample plots is uneven.The species with the largest number and wide distribution in the sample plot are Psychotria morindoides,which is the dominant species in the seedling layer.The dominant species in the plot has a significant dominant position,and most species are rare.The fluctuation of the composition and number of seedlings is small,and the average survival rate is 3.97%,and the average mortality rate is 8.29%.The structure of the seedling layer is stable.(2)During two monitoring periods,the relative importance of density dependence,environmental factors,and functional traits on seedling survival was not the same.At the community level,the effect of initial seedling height on survival varied with seedling periods.The total neighboring density of seedling had a positive effect on the survival of target individuals.Neighboring heterospecific seedlings had a significant negative effect on seedling survival,and high leaf weight and large leaf area were negatively correlated with seedling survival.At the species level,density dependence and functional traits on seedling survival varied with species change.Overall,this study elucidates the effects and relative importance of biotic and abiotic factors on seedling survival during the key seedling stage of subtropical forest plants.The Gaoligong Mountain is one of the global hotspot of biodiversity and the results provide data support for further exploration of the theory of species coexistence in subtropical forests and scientific basis for biodiversity conservation and natural resource education.