【摘要】 【目的】探讨毛竹扩张对阔叶林树木树冠结构和林元结构的影响及机制，为控制毛竹扩张和实现森林可持续经营提供理论依据。【方法】在江西阳际峰国家级自然保护区建立8 hm~2(400 m×200 m）固定监测样地，并对样地内胸径（DBH）大于1 cm的植物进行每木检尺和定位，记录植物的种类、胸径、冠长、冠幅及空间位置。分析毛竹扩张对常绿树和落叶树冠幅、冠长、冠长率、冠形率的影响，以及毛竹扩张对常绿树和落叶树林元包围度、混交度、开敞度的影响。【结果】（1）毛竹的快速扩张对邻近树木的冠层形态产生了显著影响。统计分析显示，随着毛竹数量的上升，树木的平均冠幅和冠形率呈现明显的递减趋势（P<0.01），其中常绿树种的冠幅和冠形率变化幅度显著高于落叶树种。相关性分析发现，毛竹数量与常绿树种的冠长和冠长率存在显著的负相关关系（P<0.05），而与落叶树种则未表现出相关关系（P>0.05）。（2）林元空间结构特征与毛竹数量存在显著关联。具体而言，随着毛竹数量的增加，不同尺度上树木的包围度和混交度指数均呈现上升趋势（P<0.01），而开敞度则显著降低（P<0.01）。落叶树种所在林元空间结构参数（包括包围度、混交度和开敞度）与毛竹数量的拟合度更高，表明其响应关系更为显著。（3）树木林元包围度与常绿树冠幅、冠长、冠形率及落叶树冠幅呈显著负相关（P<0.05）；林元混交度与常绿树冠幅、冠长率及落叶树冠幅、冠长、冠形率呈显著负相关（P<0.05）；林元开敞度与常绿树和落叶树冠幅、冠长、冠形率均呈显著正相关（P<0.05）。【结论】毛竹扩张会显著改变周边常绿和落叶树种的邻域环境，即增大树木林元包围度和混交度，减小树木林元开敞度。这种变化进一步引发植物个体树冠结构的减小和长势的减弱，其中常绿树种的冠幅、冠长及冠形率受到的影响尤为显著。研究结果可为毛竹扩张对森林功能影响评价提供理论依据。更多还原

【Abstract】 [Objective]The objective of this study is to explore the effects and mechanisms of Phyllostachys edulis expansion on tree canopy structure and object-neighborhood community in broad-leaved forests,thus providing a theoretical basis for controlling Ph.edulis expansion and realizing sustainable forest management.[Method]In this study,an 8 hm~2 (400 m×200 m) fixed monitoring plot was established in Yangjifeng National Nature Reserve,Jiangxi Province,and the plants with DBH greater than 1 cm in the sample plot were measured and located per tree,the species,DBH,crown length,crown width and spatial position of the plants were recorded.The effects of Ph.edulis expansion on crown width,crown length,crown length rate and crown shape rate of evergreen and deciduous trees,as well as the effects of Ph.edulis expansion on the encirclement,mixing degree and openness of evergreen and deciduous trees,were studied.[Result]The results showed that:(1) The rapid expansion of Ph.edulis had a significant impact on the canopy morphology of neighboring trees.The statistical analysis showed that with the increase of the number of Ph.edulis,the average crown width and crown rate of trees showed a decreasing trend (P<0.01),and the changes of crown width and crown rate of evergreen tree species were significantly higher than those of deciduous tree species.Correlation analysis showed that there was a significant negative correlation between the number of Ph.edulis and the crown length and crown length rate of evergreen tree species (P<0.05),but not with deciduous tree species (P>0.05).(2) There was a significant correlation between object-neighborhood community of broadleaved forest and the number of moso bamboos.Specifically,with the increase of the number of moso bamboos,the envelopment and mixing index of trees at different scales showed an upward trend (P<0.01),while the openness decreased significantly (P<0.01).object-neighborhood community of broadleaved forest parameters(including envelopment,hybridity and openness) of deciduous tree species were more consistent with the number of Phyllostachys edulis,indicating that the response relationship was more significant.(3) There was a significant negative correlation between tree encirclement and evergreen crown width,crown length,crown shape rate,and deciduous crown width (P<0.05).The degree of tree hybridity was significantly negatively correlated with the crown width and crown length rate of evergreen trees,and the crown width,crown length and crown shape rate of deciduous trees (P<0.05).Tree openness was significantly positively correlated with crown width,crown length and crown shape rate of evergreen and deciduous trees (P<0.05).[Conclusion]The expansion of Ph.edulis significantly changed the neighborhood environment of the surrounding evergreen and deciduous tree species,that is,the encirclement and mixing degree of trees increased,and the openness of trees reduced.This change further led to the reduction of the canopy structure and the weakening of the growth of individual plants,and the crown width,crown length and crown shape rate of evergreen tree species were particularly affected.This study can provide a theoretical basis for the evaluation of the impact of Ph.edulis expansion on forest function.更多还原