Architectural differences associated with functional traits among 45 coexisting tree species in Central Africa

Architectural traits that determine the light captured in a given environment are an important aspect of the life-history strategies of tropical tree species. In this study, we examined how interspecific variation in architectural traits is related to the functional traits of 45 coexisting tree species in Central Africa. At the tree level, we measured tree diameter, total height and crown dimensions for an average of 30 trees per species (range: 14-72, total 968 trees) distributed over a large range of diameters (up to 162 cm). Using log-log models, we fitted species-specific allometric relationships between tree diameter, height and crown dimensions. At the species level, we derived architectural traits (height and crown dimensions) at 15 cm and maximum diameters from species-specific allometries. The architectural traits were then related to functional traits, including light requirements, wood density, leaf habit and dispersal mode. Among the 45 coexisting tree species, we identified strong variations in height and crown allometries, along with architectural traits derived from these species-specific allometries. There was a positive correlation among architectural traits, suggesting that large-statured canopy species were taller and had larger and deeper crowns than small-statured understorey species at all ontogenic stages. The relationships between architectural and functional traits highlighted a continuum of species between the large-statured canopy species and the small-statured understorey species. In this moist and seasonal forest, large-statured canopy species tended to be light-demanding, wind-dispersed, deciduous and large contributors to forest biomass (high basal area), while small-statured understorey species tended to be shade-tolerant, animal-dispersed, evergreen and most abundant in terms of stem density. Our results highlighted strong architectural differences among coexisting tropical tree species in Central Africa. The relationships between architectural and functional traits provided insights into the life-history strategy of tropical tree species. A is available for this article.