Associations among species traits, distribution, and demographic performance after typhoon disturbance for 22 co-occurring woody species in a mesic forest on a subtropical oceanic island.

ABSTRACT

To support conservation and restoration, it is important to understand how differences in species functional traits relate to the distribution and demographic performance (i.e., changes in rates of growth, survival and recruitment) of co-occurring endemic, indigenous, and alien species on oceanic islands, where species are especially vulnerable to invasion. We examined interspecific differences in leaf and wood traits, and their associations with species origin (endemic, indigenous, and alien), distribution patterns, and demographic performance after typhoon disturbance for 22 co-occurring woody species at Sekimon on Hahajima Island in the Ogasawara Islands. Principal components analysis showed that the first and second principal components were associated with trait variations along spectra of leaf and wood economics (LES and WES). Species origin was not significantly associated with these components. Conservative species with low resource acquisition along the LES were abundant before the typhoon but acquisitive species had higher recruitment after the typhoon. After the typhoon, acquisitive species along the WES showed higher recruitment, relative growth rates but low survival rates on soil substrates. Endemic and indigenous species had lower recruitment and relative growth rates and endemic species had lower survival rates than alien species. Alien, endemic and indigenous species have similar functional space along the LES and WES, but these functional differences do not simply explain high demographic performance of alien species after the typhoon under the conditions of the species composition shifting from endemic species to alien species after repeated typhoon disturbances.