Sympatric congeneric coexistence of species is a remarkable feature which causes high alpha
diversity in tropical forests. Understanding how niche partitioning and dispersal limitations affect
sympatric congeneric coexistence of species would help us explain the high species diversity
of forests. In this study, environmental factors, leaf functional traits, and spatial distributions of 3
congeneric subcanopy tree species, Helicia formosana, H. rengetiensis, and H. cochinchinensis,
were surveyed in order to understand the coexistence of these 3 species in the subtropical Lienhuachih
forest dynamics plot in Taiwan. A bivariate point pattern analysis was used to test the relationship
among the 3 Helicia species. Principal coordinates of neighbor matrices (PCNMs) and
variation partitioning were used to study niche partitioning and dispersal limitations that affect the
distributions of the 3 species. In addition, we also calculated community-weighted means of leaf
functional traits to test trait-environment relationships. Results of the bivariate point pattern analysis
showed repulsion between each 2 pairs of the 3 species. The PCNM and variation partitioning
results explained 60.6% of the variations in niche partitioning. Our results also supported habitat
divergence affecting the distributions of these 3 Helicia species and which was also reflected in
the divergence of leaf functional traits. Overall, our results concluded that niche partitioning is the
main process affecting the distributions of the 3 Helicia species. Meanwhile, it also affects the leaf
functional traits of the 3 Helicia species and maintains the coexistence and species diversity of
congeneric coexistence of species in the Lienhuachih forest.