Analysis of main factors affecting seedling survival in Badagongshan evergreen and deciduous broad-leaved mixed forest

The seedling stage is the most vulnerable stage of life for a plant, and analysis of the factors influencing seedling survival can help us understand species coexistence mechanisms. We examined the importance of biotic and abiotic factors using Generalized Linear Mixed Models with survival data from 3554 seedlings of 128 species in a 25 hm² Badagongshan forest dynamic plot in central China. Results showed that:(1) At the community level, focal seedling survival was significantly negatively correlated with conspecific neighbor density, indicating negative density-dependence (NDD) effects in this plot, but was positively related to canopy openness. (2) At the age class, the survival of <4-year-old seedlings showed significant negative correlation with conspecific neighbor density; for seedlings ≥ 4 years old, the importance of NDD was exceeded by environmental factors. (3) Compared with the evergreen species, the survival rate of deciduous species was more susceptible to conspecific neighbor density, and significantly positively related to canopy openness. (4) The effects of biotic and abiotic factors on seedlings differed among species. For instance, Machilus ichangensis Rehd. et Wils. was positively related to canopy openness, whereas Symplocos anomala Brand seedling survival showed significant negative correlation with conspecific neighbor density, heterospecific adult basal area, and canopy openness, and significant positive correlation with heterospecific seedling neighbor density and elevation.