濒危树种闽桦天然林优势种群生态位特征

Niche characteristics of dominant populations in Betula fujianensis J.Zeng,Jian H.Li&Z.D.Chen natural forest

为了解濒危树种闽桦(Betula fujianensis J.Zeng,Jian H.Li&Z.D.Chen)群落主要植物种群的生态位特征,利用Levins和Shannon-Wiener生态位宽度、Levins生态位重叠指数对福建省三明市罗卜岩保护区闽桦群落的乔、灌和草本层主要种群的生态位特征进行了定量分析,并基于生态位重叠值将主要种群进行了聚类分析。结果显示:(1)乔木层闽桦和闽楠(Phoebe bournei(Hemsl.)Yang)的重要值和生态位宽度均最高,是群落的优势种,其次为台湾冬青(Ilex formosana var.macropyrena S.Y.Hu)、刺毛杜鹃(Rhododendron championiae Hooker)、黄枝润楠(Machilus versicolora S.K.Lee et F.N.Wei),是群落的亚优势种;灌木层中草珊瑚(Sarcandra glabra(Thunb.)Nakai)、细枝柃(Eurya loquaiana var.aureopunctata Hung T.Chang)、单耳柃(Eurya weissiae Chun)具有较高的生态位宽度,为灌木层优势种;草本层瘤足蕨(Plagiogyria adnata(Bl.)Bedd.)、肾蕨(Nephrolepis cordifolia(L.)C.Presl)和狗脊蕨(Woodwardia japonica(L.f.)Sm.)的重要值和生态位宽度均较大,为草本层优势种。(2)乔木层主要物种间生态位重叠较为普遍,但重叠程度较高的仅有62对,占19.1%,另有12.3%的种对生态位完全分离;灌木层生态位重叠值较高的种对有236对,占67.2%,仅4对发生生态位分离;草本层生态位重叠值较高的种对有43对,占22.6%,有39对发生生态位分离;(3)将闽桦群落不同层次物种进行聚类,闽桦群落乔木层和灌木层均可以划分为4组,草本层可划分为3组。总体来看,闽桦群落不同层次种间关系较为协调,群落整体稳定性较高。

This study investigated the niche characteristics and interspecific relationships among dominant species at different levels within the Betula fujianensis J.Zeng,Jian H.Li&Z.D.Chen community in Luobuyan Nature Reserve of Sanming City,Fujian Province,China,to inform conservation and restoration strategies.Based on sample plots,both niche breadth and overlap of the dominant populations in the tree,shrub,and herbaceous layers of the B.fujianensis community were quantitatively analyzed using Levins and Shannon-Wiener niche breadth and Levins niche overlap indices,respectively,with cluster analysis subsequently carried out based on niche overlap.Results showed that:(1)B.fujianensis and Phoebe bournei(Hemsl.)Yang were the dominant species in the tree layer,followed by subdominant species Ilex formosana var.macropyrena S.Y.Hu,Rhododendron championiae Hooker,and Machilus versicolora S.K.Lee et F.N.Wei.Sarcandra glabra(Thunb.)Nakai,Eurya loquaiana var.aureopunctata Hung T.Chang,and Eurya weissiae Chun were the dominant species in the shrub layer,while Plagiogyria adnata(Bl.)Bedd.,Nephrolepis cordifolia(L.)C.Presl,and Woodwardia japonica(L.f.)Sm.were the dominant species in the herbaceous layer.(2)Niche overlap of the main species in the tree layer was relatively low,with only 62 species pairs(19.1%)showing a high degree of overlap,while 12.3%of species pairs showed complete niche separation,indicating no intense interspecific competition in this layer.Conversely,236 species pairs(67.2%)showed high niche overlap in the shrub layer,while only four species pairs showed niche separation,indicating that most shrub layer plants had similar or common resource needs.In the herbaceous layer,43 species pairs(22.6%)exhibited a high degree of niche overlap,while 39 species pairs showed niche separation,suggesting distinct resource niches and coordinated interspecific relationships.(3)Based on niche overlap,cluster analysis revealed that species in the different layers of the B.fujianensis community were clustered together,with the tree and shrub layers divided into four groups and the herbaceous layer divided into three groups.Overall,results indicated that the B.fujianensis community demonstrated high stability.These findings have important theoretical and practical value for guiding the protection and restoration of B.fujianensis communities.