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...