Inter-specific and sexual differences in architectural traits of two dioecious Lindera species (Lauraceae)

The architecture of trees is a crucial determinant of their performance through light capture and mechanical stability. Comparison of architectural traits between closely related dioecious species is predicted to reveal both inter-specific and sexual differences. The former may reflect life-history characteristics such as microhabitat preferences, and the latter may reflect costs of reproductive allocation. We measured branching structure, leaf traits, wood density, and biomass of each vegetative component in the dioecious shrubs Lindera praecox and Lindera triloba to explore architectural differences according to species and gender. L. triloba was less branched but had a greater total leaf mass per shoot having larger and heavier leaves than L. praecox ; most of these traits did not differ by gender. Allometric relationships between height and branch biomass corroborated our results of branching structure. The allometric relationships between tree size and leaf biomass demonstrated that in larger size classes females of both species had greater leaf biomass than males. Females of both species also showed lower tree height than males. This study suggests that tree architecture is influenced by both life-history strategy and resource-allocation pattern. Branching structure and branch biomass showed inter-specific differences, with the highly branched L. praecox apparently more shade tolerant than L. triloba ; its tolerance is likely adaptive in its preferred microhabitat where is often lit poorly. Sexual differences in leaf biomass and tree height growth may reflect higher reproductive costs incurred by females.