Effects of an alien shrub species, Leucaena leucocephala, on establishment of native mid-successional tree species after disturbance in the national park in the Chichijima island, a subtropical oceanic island

Abstract

Effects of an invasion of an alien shrub species, Leucaena leucocephala, were investigated on subsequent establishment of a native mid-successional wooden species, Schima mertensiana at early-successional stages after disturbance in a subtropical oceanic island, Chichijima in Japan. Changes in basal areas, densities and size distribution of forests at a site dominated by L. leucocephala were compared with those at a site dominated by native shrub species, Trema orientalis at early-successional stages. Effects of L. leucocephala on germination of seeds and growth of seedlings of S. mertensiana were quantified at the sites. There were few recruited seedlings of S. mertensiana and they did not grow at the site dominated by L. leucocephala. On the other hand, there were a few recruited seedlings within a 1 m x 1 m area and they positively grew at the site dominated by T. orientalis. Germination rates of seeds and growth rates of seedlings of S. mertensiana at the site dominated by L. leucocephala were lower than those at the site dominated by T. orientalis. Germination of seeds and growth of seedlings of S. mertensiana were inhibited by L. leucocephala at the disturbed site, which potentially changed an early successional pathway of the plant community.