青城山常绿阔叶林冠层结构对植被生物多样性的影响

Effect of canopy structure on plant diversity of evergreen broadleaved forest in Qingcheng Mountain

【目的】分析青城山常绿阔叶林冠层结构与植被生物多样性的关系.【方法】在青城山常绿阔叶林地段设立样方,调查了森林植被特征,并运用冠层分析仪测定了森林的冠层结构和光环境特征.【结果】青城山常绿阔叶林乔木和灌木层物种丰富度、Simpson多样性指数和均匀度均高于草本层,乔木层丰富度高于灌木层,但两层间的Simpson多样性指数和均匀度差异不明显.乔木、灌木和草本层的Simpson多样性指数和冠层上方的光量子通量(PPFD)显著负相关,灌木和草本层的Simpson多样性指数与冠层下方PPFD显著正相关.草本层均匀度与冠层孔隙度和开度呈正显著相关,与郁闭度呈负相关.【结论】青城山常绿阔叶林冠层结构及其引起的光环境变化对草本层的影响较乔木层和灌木层明显,尤其是对草本层物种丰富度和多样性影响更显著.在青城山低山常绿阔叶林生态系统演替进程中,林下光照强度大小是影响林下植物生长和演替的重要限制因素.

[Objective] Analyzing the relationships between the canopy structure and vegetation diversi- ty of the evergreen broadleaved forest in Qingcheng Mountain. [Method] The quadrat method and canopy analyzer were used to investigate vegetation diversity and canopy structure for the evergreen broadleaved forest,respectively. [Result] Plant species rich in Qingcheng Mountain. Simpson diversity index and the evenness in both tree and shrub layers were higher than them in herb layer. The richness in tree layer was higher than in shrub layer, but no differences were observed on diversity index and evenness between these two layers. Simpson diversity index had a negative correlation with Photo synthetic Photon Flux Density （PPFD） above the canopy in tree, shrub and herb iayers, but had a positive correlation with PPFD below canopy in shrub and herb layers. The evenness wag positive correlation with gap fraction and openness, but negative correlation with canopy closure in herb layer. [Conclusion] Light environment caused by the difference of canopy structure has larger effect on herb layer than that on tree and shrub layers. The under-story light intensity is the maior factor controlling vegetation growth and succession in evergreen broad- leaved forest in Qingcheng Mountain.