Common Species in the Subtropical Evergreen Broad-Leaved Forest: Dominance in Adaptation Mechanisms and Resource Utilization Capabilities

When species of different abundance coexist, their ecological strategies remain uncertain. Assessing the functional diversity and niche characteristics of species with different levels of abundance contributes to understanding vegetation properties and is essential for species conservation. Based on the species abundance of 380 plots in the Gutianshan subtropical evergreen broad-leaved forest in the Zhejiang Province of China, woody plants were categorized as common species (86 species), occasional species (87 species), and rare species (79 species). Plant functional traits, including maximum height, seed dispersal modes, first flowering stage, flowering duration, and fruit length, were used to assess the functional diversity of the community of common, occasional, and rare species, while 15 environmental factors were used to evaluate their Levins’ niche breadth and Pianka’s niche overlap. The results showed that rare species have the highest functional evenness, while functional dispersion and Rao’s quadratic entropy were higher for common species (2.05 and 5.07, respectively) compared to occasional species (1.57 and 3.10) and rare species (1.35 and 2.48). Furthermore, the 15-dimensional mean value of niche breadth of common species (ranging from 0.277 to 0.955) was also higher than that of occasional (ranging from 0.193 to 0.710) and rare species (ranging from 0.100 to 0.345), and the same trend was also observed in niche overlap. The results suggest that common species have diverse functional traits and a greater ability to adapt to the environment and use resources, whereas occasional species have a limited ability to use the environment. Rare species are evenly distributed within functional space to reduce direct competition with other species, but they thrive only under specific environmental conditions, mainly following a K reproductive strategy. Niche differentiation mechanisms are important determinants of species coexistence in subtropical evergreen broad-leaved forests. In summary, more attention and greater efforts should be paid to the conservation of rare species. Our findings could help forest managers in the restoration and conservation of subtropical forests.