Rare tree species have narrow environmental but not functional niches

1. The majority of species in many communities are rare, and it is an enduring challenge to understand the mechanism of species rarity and commonness in local communities. The niche partitioning hypotheses posit that common species occupy wide and core positions, while rare species occupy narrow and outlying niche positions. We test these hypotheses here, simultaneously considering both an environmental and a functional perspective on niches. 2. We examined how niches correlate with species abundance in environmental and functional space by quantifying relationships between species abundance and niche width and niche position. Environmental niches were defined as the section of an environmental gradient where each species occurred, and functional niches using species traits thought to be related to resource acquisition. Hypotheses were tested using a dataset including functional traits collected from 4302 individual trees of 423 species and environmental data in one subtropical and o...1. 许多群落中的大多数物种均为稀有种，解析局地群落中物种稀有与常见的形成机制，长期以来都是一项颇具挑战性的科学难题。生态位分化假说（niche partitioning hypotheses）提出，常见物种占据宽泛且核心的生态位位置，而稀有种则占据狭窄且边缘的生态位位置。本研究对此类假说进行验证，同时从环境与功能双重视角开展生态位相关研究。 2. 本研究通过量化物种多度（species abundance）与生态位宽度、生态位位置之间的关联，探究了环境空间与功能空间中生态位与物种多度的相关性。其中，环境生态位（environmental niche）被定义为各物种分布所处的环境梯度区间，功能生态位（functional niche）则采用被认为与资源获取相关的物种性状进行表征。本研究依托数据集对上述假说开展检验，该数据集包含采集自423个物种、共计4302株个体的功能性状数据，以及一处亚热带及[原文内容未完整呈现]的环境数据。