Studies On Interannual Dynamics Of Tree Seedlings And Its Influencing Factors In A Secondary Forest In Montane Region Of Eastern Liaoning Province,China

To understand the interannual dynamics of tree seedlings and its influencing factors in a secondary forest in montane region of eastern liaoning province,based on the 4 hm2 dynamic monitoring forest plot,we monitored tree seedlings with DBH < 1 cm.With quantity ecology methods,we analyzed species composition and interannual dynamics of tree seedlings from three censuses and canopy monitoring(2014 to 2016).Combining data of soil chemical properties,we analyzed the relative importance of biotic neighbors and habitat heterogeneity on the survival of perennial and recruited tree seedlings by using generalized linear mixed model.To reveal the natural regeneration rules of trees in secondary forests of this region,and provide a theoretical basis for secondary forest management and biodiversity conservation.The main conclusions are as follows:1.Tree species composition and interannual dynamic of tree seedlings showed that a total of 22 species of tree seedlings were recorded.The species composition of tree seedlings did not vary significantly among years,but varied greatly among quadrats.The composition of dominant tree species in seedlings was similar to that of dominant tree species in adults.The number of tree seedlings varied greatly among different tree species and years.There were obvious inter-species and inter-annual differences in tree seedling recuits and death.The mortality rate of recruited tree seedlings(18.8%)was also significantly higher than perennial tree seedlings(8.1%).The seedlings of dominant species showed cluster distribution,and the spatial distribution of seedlings and adults maintained a certain similarity.2.The results of factors affecting survival of perennial tree seedlings showed that the survival of perennial treeseedlings were affected by biotic neighbors and habitat heterogeneity,and the relative importance varied with shade tolerance,seed dispersal types and species.At community level,the survival of perennial tree seedlings were significantly positively correlated with seedling height,soil PC1 and elevation.The survival of perennial seedlings of both gravity-dispersal tree species and shade-tolerant tree species were significantly positively correlated with the density of conspecific seedlings.The survival of perennial seedlings of light demanding tree species,shade-tolerant tree species and wind-dispersal tree species were significantly negatively correlated with soil PC2.At the same time,the survival of perennial seedlings of wind-dispersal tree species was significantly negative correlated with slope.3.The results of factors affecting survival of recruited tree seedlings showed that at the community level the survival of recruited tree seedlings was significantly positively correlated with elevation,and significantly negatively correlated with canopy openness.The survival of recruited tree seedlings of wind-dispersal tree species and shade tolerant tree species were significantly negatively correlated with soil PC3.The survival of recruited tree seedlings of neutral tree species were significantly positive correlated with heterospecific seedlings,conspecific adult trees and slope.Compared with perennial tree seedlings,there were fewer factors that significantly affected the survival of recruited tree seedlings.There were significant differences in the factors that affect seedling survival of the same species at different life stages and habitat conditions.Based on the research results,the following suggestion are proposed for the regeneration,restoration and biodiversity conservation of secondary forest in this region:(1)The seedling of F.rhynchophylla that survived for two years or more showed significant habitat preference to weakly acidic soil,we could create an appropriate environment of weakly acidic soil for the seedling of F.rhynchophylla in the process of artificial seedling cultivation.(2)The tree seedling formed by wind-dispersal seed may not be suitable for regeneration in areas with higher slopes.(3)The recruited one-year tree seedling need moderate shade.(4)Applying appropriate K fertilizer is benefical to the survival of recruited tree seedling of wind-dispersal tree specie and shade-tolerant tree specie.