海南岛霸王岭热带天然林景观中木本植物功能型分布的影响因素

 为了探讨在热带天然林景观中不同因素对木本植物（限于乔木和灌木）功能型分布的影响，在对海南岛霸王岭的热带天然林进行样方调查的基 础上，运用数量分类方法对热带天然林的木本植物进行了功能型划分，并运用冗余度分析（Redundancy analysis, RDA） 分别探讨了功能型出 现与否、功能型物种丰富度和功能型木本植物多度3个矩阵与环境、空间和干扰因素之间的关系。运用偏冗余度分析对影响功能型分布变化的环 境、干扰、空间及其交互作用等因素进行了定量分解。结果表明：利用木材密度和潜在最大高度两个指标划分出的9个功能型，能较好的区分功 能型间对生境的适应响应差异；因子分解表明，纯环境、 纯人为干扰和混合的环境-人为干扰是影响3个功能型矩阵分布变化的主要因素，纯空 间和与空间位置相耦合的因素相对较低；在诸多因子中，干扰类型、地形因子、土壤类型、砂砾含量、土层厚度以及经纬度坐标是影响功能型 分布变化的主导因子；RDA排序分析表明，一般来讲，硬木功能型多在生境条件好和远离人为干扰的立地高发生。软木功能型则更多地出现于生 境条件恶劣和人为干扰频繁的立地。而中等硬度功能型则生态幅度较宽。但除了软木灌木功能型外，其它功能型物种丰富度和木本植物多度多 在土层深厚和生境条件较好的立地较高。

INFLUENCE OF ECOLOGICAL FACTORS ON DISTRIBUTION OF WOODY PLANT FUNCTIONAL TYPES IN A NATURAL TROPICAL FOREST LANDSCAPE, BAWANGLING, HAINAN ISLAND, SOUTH CHINA

Aims The relative influence of ecological factors on the distribution of woody plant functional types in a natural tropical forest landscape is rarely explored.The three major objectives of this study were to 1)determine the relative importance of environment,anthropogenic disturbance and spatial influences on the distribution of woody plant functional types,2)determine which variables influence distribution of woody plant functional types,and 3)examine the distribution of woody plant functional types in different habitats.Methods Using data from 135 plots in a natural tropical forest landscape of Hainan Island,South China,we classified woody plant functional types using the characteristics of species wood density and potential maximum height.Three sets were used,presence-absence,species richness and abundance.Their relations to environment,anthropogenic disturbance and spatial factors were analyzed with redundancy analysis(RDA).We then used a partial RDA with variation partitioning to specify which proportion of the variation in functional types distribution pattern is explained by each of the three factors individually and which proportion is attributable to interactions between factors.Important findings We found that environmental influence,anthropogenic disturbance and interaction between environmental and anthropogenic disturbance factors were of similar importance in functional types distribution.However,spatial influence and interaction between spatial and other factors were less important.Furthermore,we found that anthropogenic disturbance types,topographical factors,soil types,grit content,soil depth and X,Y coordinates all impacted the distribution of functional types.Generally,hardwood functional types are abundant in better,undisturbed sites,but softwood functional types occur in opposite settings.The distributional range of medium hardwood functional types is wider than the other two.Except for softwood shrub functional types,the others have high species richness and abundance in better sites,especially where soils are deep.This study suggests that the plant functional type approach enhances understanding of the relative influence of environment,anthropogenic disturbance and spatial factors on species distribution.Environment and anthropogenic disturbance are more important than spatial influence in the variation of species distribution.These conclusions can aid in developing large-scale conservation and management policies in tropical rainforest areas.