长白山阔叶红松林木本植物系统发育与功能性状结构

Functional and phylogenetic structures of woody plants in broad-leaved Korean pine mixed forest in Changbai Mountains, Jilin, China

群落构建一直是群落生态学研究的热点问题之一.以性状差异、亲缘关系等为载体的物种相似性方面的研究,能更好地反映群落格局形成的生态学过程.本文以长白山25 hm2森林监测样地内DBH≥1 cm的50种木本植物为研究对象,收集了各树种木材密度、最大树高、叶面积、比叶面积、叶片氮含量和磷含量等6种功能性状数据,构建了物种间的系统发育结构,使用K值法检验各个功能性状的系统发育信号,并在不同空间尺度上(10,20,40,60,80和100 m)使用最近亲缘指数(NTI)分析了群落系统发育和功能性状的结构,推断其潜在的生态过程.研究结果表明:(1)所有6个植物功能性状都具有显著的系统发育信号,表明该森林木本植物的功能性状受系统发育历史的影响;(2)单个功能性状的群落结构具有明显的尺度效应,在小空间尺度上,叶面积、最大树高表现为聚集,而木材密度、叶片磷含量、叶片氮含量和比叶面积则为发散;在大空间尺度上各功能性状主要呈聚集或随机结构;(3)群落的系统发育与功能性状结构具有明显的尺度效应,在小尺度上(<40 m)2种结构均呈发散,表明竞争排斥占主导地位;随着空间尺度的增大,2种群落结构转变为随机状态,这主要由于具有相反作用的非中性过程交互作用的结果.不同空间尺度的功能性状与系统发育结构的研究表明,非中性过程在长白山温带阔叶红松林的生物多样性维持中具有重要作用.

Studies on the evolutionary and functional similarity of species can provide new insights into the mechanisms of community assembly, a well-known and important part of community ecology. We measured six functional traits of 50 woody species （wood density, maximum plant height, leaf area, specific leaf area, and leaf nitrogen and phosphorus contents） in a well-mapped 25 hm2 broad-leaved Korean pine mixed forest plot in Changbai Moutains, Jilin Province, China, and tested the phylogenetic signals of these traits. Next, we calculated the functional and phylogenetic structures using a nearest taxon index （NTI） to examine the underlying ecological processes at different spatial scales （10, 20, 40, 60, 80 and 100 m）. We found （1） all six functional traits showed significant phylogenetic signals, suggesting close related species have similar ecological characteristics; （2） the functional structure of individual traits showed strong scale dependency. At fine scales, leaf area and maximum plant height were clustered while wood density, leaf phosphorus content, leaf nitrogen content and specific leaf area were overdispersed. At larger scales, most traits showed functional overdispersion or random; （3） the functional and phylogenetic structures differed with spatial scale. At fine scales （〈 40 m）, phylogenetic and functional structures were overdispersed, indicating strong effects of competitive exclusion. At larger scales, phylogenetic and functional structures were random, because of the effects of opposing non-neutral processes. The study of functional and phylogenetic structures at different spatial scales reflects the important roles of non-neutral processes in maintaining diversity in this forest.