中亚热带喀斯特森林树木功能型的生态位特征

Niche Characterization of Tree Functional Types in a Central Subtropical Karst Forest

【目的】分析中亚热带喀斯特森林树木功能型的生态位特征,推断不同功能型树木对资源的利用程度和种间竞争差异,为喀斯特地区的植被恢复与重建提供理论指导。【方法】以中亚热带喀斯特常绿落叶阔叶混交林为研究对象,在样地调查基础上根据冠层高度、种群大小、耐荫性和种子传播方式将被选的40种树木划分为不同功能型,通过计测生态位宽度和生态位重叠指数分析不同功能型树木的生态位特征。【结果】喀斯特森林树木的生态位宽度普遍较低,表现为常见种>偶见种>稀有种,且三者的生态位宽度间差异显著;重力传播种的生态位宽度显著低于动物和风力传播种,不同耐荫性和冠层高度功能型间的生态位宽度无显著差异;40种树木种对间的生态位重叠指数同样较低,常见种的生态位重叠指数显著高于偶见种和稀有种,上层种显著高于下层种,喜光种显著高于耐荫种,而重力传播种则显著低于动物和风力传播种;常见种与偶见种间的生态位重叠指数显著高于常见种与稀有种以及偶见种与稀有种间,动物与风力传播种间的生态位重叠指数显著高于动物与重力种间以及风力与重力种间,而中生与耐荫种间的生态位重叠指数则显著低于喜光与中生种以及喜光与耐荫种间。【结论】中亚热带喀斯特常绿落叶阔叶混交林中多数树种占据较小的生态位空间并可能存在较低的种间竞争作用,不同树木功能型生态位宽度和生态位重叠指数的差异可能与生境异质性和物种性状差异等存在密切联系。在进行退化生境植被重建时,可根据不同功能型树木的生态位特征合理构建群落的组成与结构,促进森林植被快速恢复。

【Objective】By analyzing the niche characterization of tree functional types(TFTs)in a central subtropical karst forest,we can infer the differences in resource utilization and interspecific competition among different TFTs,providing theoretical guidance for vegetation restoration and reconstruction in karst areas.【Method】Based on plot surveys in the subtropical karst evergreen-deciduous broadleaved mixed forest in central subtropical China,the 40 tree species were selected and classified into different functional types according to canopy height,population size,shade tolerance,and seed dispersal mode.The niche characterization of the tree species in different functional types were analyzed by measuring niche breadth and niche overlap index.【Result】The niche breadths of tree species in the karst forest are generally low,with the ranking of common species>occasional species>rare species,and there are significant differences among them.The niche breadths of gravity dispersed species are significantly lower than those of animal dispersed and wind dispersed species,while there are no significant differences in niche breadths between different TFTs with different shade tolerance and canopy height.The niche overlaps among the 40 tree species are also low,with significantly higher overlap between common species compared to occasional and rare species,and significantly higher overlap for overstory species compared to understory species.Light demanding species have significantly higher overlaps compared to shade tolerant species,while gravity dispersed species have significantly lower overlaps compared to animal dispersed and wind dispersed species.The overlaps between common and occasional species are significantly higher than those between common and rare species,as well as those between occasional and rare species.The overlaps between animal dispersed and wind dispersed species are significantly higher than those between animal dispersed and gravity dispersed species,as well as those between wind dispersed and gravity dispersed species.However,the overlaps between mid-tolerant and shade tolerant species are significantly lower than those between light demanding and mid-tolerant species,as well as those between light demanding and shade-tolerant species.【Conclusion】Most tree species in the subtropical karst evergreen and deciduous broad-leaved mixed forest occupy relatively small niche spaces and may have lower interspecific competition.The differences in niche breadth and overlap among different TFTs may be closely related to habitat heterogeneity and species trait differences.When conducting vegetation restoration in degraded habitats,the composition and structure of the community should be reasonably constructed based on the niche characterization of different TFTs,thereby promoting recovery of forest vegetation.