Relationship between tree growth and stand structure in evergreen broad-leaved forests

<bold>Objective</bold> Studying the relationship between stand structure and tree growth at different stages in subtropical evergreen broad-leaved forests helps understand the dynamics and variability of tree development in spatial and temporal dimensions.This clarifies forest succession trends and provides significant guiding significance for vegetation restoration and optimizing stand structure. <bold>Method</bold> Taking the fixed monitoring plot of 2 hm² evergreen broad-leaved forest in Qiyun Mountain as the research object，the trees in the sample plot were divided into four growth stages：sapling trees，small trees，middle trees and large trees，and three stand structure parameters，namely angular scale，mixed tree and dominance degree，were selected to explore the effects of stand structure on the annual average growth of all trees and trees of different life forms at different growth stages. <bold>Result</bold> （1）The same stand structure parameters had a significant effect on the annual basal area growth rate of all trees at different growth stages（<italic>P</italic>&lt;0.05），impacts become progressively smaller as trees increase in size class，while different stand structure parameters only had a significant effect on the dominance of young trees（<italic>P</italic>&lt;0.05）.（2）The same stand structure parameters had a significant effect on the average annual growth of saplings，small trees and middle trees of different life forms（<italic>P</italic>&lt;0.05），due to that the angular scale had a significant effect on young and middle trees（<italic>P</italic>&lt;0.05），the degree of mixing had a significant effect on small and middle trees（<italic>P</italic>&lt;0.05），and the dominance degree had a significant effect on young and small trees（<italic>P</italic>&lt;0.05）. <bold>Conclusion</bold> Trees in evergreen broad-leaved forests are affected by the stand structure at different growth stages.Small-diameter trees are most affected，while the annual basal area growth rate of medium-diameter trees maintains stable growth，and large-diameter trees are less affected.Among different life forms，stand structure has a greater impact on deciduous trees.With the increase of diameter class，the average annual growth of basal area in deciduous tree species is gradually lower than that of evergreen tree species.This study suggests that the region is in the transition phase from mid-to-late succession stages to the climax stage，and measures can be reasonably formulated to optimize the spatial structure of forest metaspace according to the law of tree growth，and accelerate the development of forest succession to climax communitie through long-term monitoring and protection.