桂林岩溶石山青冈群落数量分类与排序

Numerical classification and ordination of Cyclobalanopsis glauca communities in karst hills of Guilin, Southwest China

植物群落的数量分类和排序可以客观地揭示植物群落与环境之间的关系,从而能为植被恢复与重建、森林经营与管理和生物多样性保护等提供理论依据。基于群落学调查和环境因子测定数据,采用Ward聚类、双向指示种分析(TWINSPAN)和多元回归树(MRT)对桂林岩溶石山青冈群落进行数量分类,选用冗余分析(RDA)进行排序,分析其与环境因子之间的关系。结果表明:(1)3种分类方法所得结果基本一致,可将桂林岩溶石山青冈群落划分为3个群丛类型,分别为青冈 粗糠柴+龙须藤+红背山麻杆 三穗薹草群丛(Ass.Cyclobalanopsis glauca Mallotus philippensis+Bauhinia championi+Alchornea trewioides Carex tristachya)、青冈 龙须藤+红背山麻杆+干花豆 宽叶沿阶草+三穗薹草群丛(Ass.Cyclobalanopsis glauca Bauhinia championi+Alchornea trewioides+Fordia cauliflora Ophiopogon platyphyllus+Carex tristachya)、青冈 粗糠柴+干花豆 三穗薹草群丛(Ass.Cyclobalanopsis glauca Mallotus philippensis+Fordia cauliflora Carex tristachya);(2)冗余分析结果较好地反映出各群丛类型的分布格局及其与环境梯度的相互关系,在10个环境因子中,岩石裸露率、土壤含水量、pH值、全氮、全磷、全钾、速效钾这7个环境因子对群落的分布影响显著。土壤含水量和全钾含量可能是影响该植物群落物种组成与分布的重要生态因子。

The plant community is an assemblage of plant populations that live in certain area,and interact with and adapt to each other in the context of long term environmental changes.The quantitative analysis of forest community is an important approach to research the community classification and sorting.The numerical classification and ordination of plant communities can objectively reveal the ecological relationship between plant communities,distribution and the environmental factors which provides the important theoretical basis for forest vegetation restoration and reconstruction,forest management,and biodiversity conservation.Although a fast growing literature on the numerical classification and ordination of plant communities are published in recent years,yet little is known about the numerical classification and ordination of Cyclobalanopsis glauca communities in karst hills of Guilin,Southwest China,which prevents us from to determine the environmental factors influencing the distribution of Cyclobalanopsis glauca communities.Therefore,it is necessary to carry out a case study about the numerical classification and ordination of Cyclobalanopsis glauca communities in karst hills of Guilin.To explore this uncertainty,based on the environmental factors and community structure data by the systematic field investigation of 20 plots of Cyclobalanopsis glauca communities,we conducted the quantitative classification of Cyclobalanopsis glauca communities with Ward clustering,two way indicator species analysis(TWINSPAN),and multivariate regression trees(MRT)methods.The relationship between the distribution of species and environmental factors was analyzed by the redundancy analysis(RDA)ordination method.The results showed that:(1)the results of the three classification methods were basically consistent.The 20 plots of Cyclobalanopsis glauca communities in karst hills of Guilin were divided into 3 associations types:Ass.Cyclobalanopsis glauca Mallotus philippensis+Bauhinia championi+Alchornea trewioides Carex tristachya,Ass.Cyclobalanopsis glauca Bauhinia championi+Alchornea trewioides+Fordia cauliflora Ophiopogon platyphyllus+Carex tristachya,Ass.Cyclobalanopsis glauca Mallotus philippensis+Fordia cauliflora Carex tristachya.(2)Both redundancy analysis and three numerical classification exhibited consistent results.The redundancy analysis clearly reflected the distribution range of three association types and the relationships between association types and the environmental factors.Among 10 environmental factors,the rock bare rate,soil water content,soil pH value,soil total nitrogen,soil total phosphorus,soil total potassium,and available potassium have significant effects on the distribution across the 3 associations types.The changes of soil water content and total potassium content were main ecological factors influenced the composition and distribution of Cyclobalanopsis glauca communities in karst hills of Guilin,Southwest China.