径阶距对评估南盘江流域天然林物种多样性的影响  

Evaluating influences of diameter classes on the species diversity of natural forests in the Nanpan River basin

作　　者：黎明慧 李远发[1] LI Minghui;LI Yuanfa(College of Forestry,Guangxi Key Laboratory of Forest Ecology and Conservation,Guangxi University,Nanning 530004,China)

机构地区：[1]广西大学林学院,广西森林生态与保育重点实验室,广西南宁530004

出　　处：《南京林业大学学报（自然科学版）》2023年第4期166-174,共9页Journal of Nanjing Forestry University：Natural Sciences Edition

基　　金：国家自然科学基金项目(32060340,31400542)。

摘　　要：【目的】物种多样性和树木大小是决定森林生态系统稳定性、复杂性的关键因素,也是森林生态系统多样性的典型表征,用长时间未受外界干扰的标准固定样地数据对物种多样性和树木大小的关系进行研究,揭示径阶距和直径分布范围对物种多样性的影响。【方法】在广西雅长兰科植物国家级自然保护区建立了3块不同年龄序列的标准固定样地(30年生林分,代号30⁃YF;57年生林分,代号57⁃YF;200年生林分,代号200⁃YF),采用2、3、4、5 cm作为径阶距划分直径分布,并计算每个径阶上的物种多度(number of individual,N)、物种丰富度(species richness,RS)、多样性指数(Simpson,D;Brillouin,BH)和均匀度指数(Pielou,E_(H);Sheldon,E_(S))。【结果】①物种多度和丰富度随径阶的增大逐渐减小,呈倒“J”形分布;且随径阶距增大而增大,曲线的弯曲程度提高。②多样性指数随着径阶的增大线性降低,受径阶距的影响很小(P>0.05)。③整体上,径阶增大将促进种间多度的平衡。Pielou均匀度指数随径阶增大出现波动,而Sheldon均匀度指数呈线性增大,受径阶距的影响小(P>0.05);④只有当径阶距为2 cm时,林分间的物种多样性指数差异显著(P<0.05)。【结论】径阶距对同一林分内物种多样性的影响不大,但林龄会加强径阶距对物种多样性的影响,强调了直径分布范围和小树对物种多样性的显著影响。2 cm比其他径阶距能更好地反映南盘江流域天然林之间物种多样性的差异,亦说明了它被广泛使用的合理性。【Objective】Species diversity and tree size play an important role in maintaining the stability and complexity of forest ecosystems,and also characterize the diversity of forest ecosystems.The relationship between species diversity and tree size is not well understood.【Method】Three fixed plots(30⁃year⁃old forest,30⁃YF;57⁃year⁃old forest,50⁃YF;200⁃year⁃old forest,200⁃YF)located at Guangxi Yachang orchid national reserve were established and their diameter distributions were divided using diameter classes of 2,3,4 and 5 cm.The number of individuals(N),species richness(RS),diversity(Simpson,D;Brillouin,BH),and evenness(Pielou,E_(H);Sheldon,E_(S))were calculated for each diameter class.【Result】(1)N and RS displayed a reversed J shape,decreasing with the increase in diameter.N and RS increased with increasing diameter class,and their curves became more bent.(2)D and BH were slightly affected by diameter class and showed a linear decrease(P>0.05).(3)Overall,increasing tree diameter promoted a balance of abundance among tree populations.With an increase in diameter,EH fluctuated and ES increased linearly and was slightly affected by the diameter classes(P>0.05).(4)A significant difference in species diversity indices was found among the three stands(P<0.05)when the diameter class was 2 cm.【Conclusion】Diameter class had little effect on species diversity within the same stand.However,stand age enhanced this effect,highlighting the importance of the diameter range and small trees on species diversity.The diameter of 2 cm better reflects the diversity of species among natural forests in the Nanpan River basin than the other diameter classes.This justifies its widespread use.

关 键 词：天然林 树木大小 径阶距 丰富度 多度 均匀度 南盘江流域 

分 类 号：S718[农业科学—林学]