湖南八大公山黄杉种群结构和群落特征研究

利用样方法对湖南八大公山黄杉(Pseudotsuga sinensis Dode)群落进行调查,分析黄杉群落的物种组成、区系特征、径级结构和物种多样性。结果显示,群落内共有维管植物132种,隶属于48科89属。群落垂直结构明显,分为乔木层、灌木层和草本层,黄杉是乔木层的优势种,另有檵木(Loropetalum chinense(R.Br.)Oliver)、马尾松(Pinus massoniana Lamb)和油桐(Vernicia fordii(Hemsl.)Airy Shaw)等主要伴生种,檵木为灌木层优势种,两色鳞毛蕨(Dryopteris setosa(Thunb.)Akasawa)为草本层优势种。群落区系组成以泛热带分布和北温带分布为主,具有明显的亚热带向温带过渡的性质。种群年龄结构可分为稳定型向衰退型过渡和衰退型2个类型,样方中幼苗和幼树极度缺失,中龄和老龄个体居多。黄杉、钩栲针阔混交林的物种多样性高于黄杉纯林,其中灌木层的多样性指数最高,乔木层的物种多样性指数最低。群落冠层郁闭度高造成的幼苗缺失可能是影响其濒危的主要原因,建议采取人为干扰创造林窗、加快繁殖技术研究等措施扩大其种群数量。

Population structure and community characteristics of Pseudotsuga sinensis Dode in Badagongshan,Hunan Province,China

Pseudotsuga sinensis is a National ClassⅡprotected plant species.To understand its population dynamics and underlying mechanism,we investigated the P.sinensis communities in the largest distribution area in Badagongshan,Hunan Province,China,and analyzed the species composition,vertical structure,size structure,and species diversity.Results showed that:(1)A total of 132 vascular plant species were recorded,belonging to 89 genera in 48 families.The canopy was divided into distinct tree,shrub,and herb layers.Pseudotsuga sinensis was the dominant tree-layer species,with Loropetalum chinense,Pinus massoniana,and Vernicia fordii as companion species.Loropetalum chinense was the dominant shrub-layer species and Dryopteris setosa was the dominant herb-layer species;(2)Most species in the community were subtropical to temperate zone transition species;(3)The P.sinensis population was divided into two types:stable to decaying stage and declining population stage;(4)Species diversity in the P.sinensis and Castanopsis tibetana mixed forest was higher than that in the P.sinensis forest.The highest species diversity was found in the shrub layer,followed by the tree and herb layers.Seedlings and saplings were lacking in the six study plots,thus potentially affecting population stability.This may be due to high canopy closure,which can inhibit seedling regeneration.We suggest that creating canopy gaps and long-term monitoring may help species regeneration and population stability.