Eighty Years of Succession in a Noncommercial Plantation on Hawai'i Island: Are Native Species Returning?

Abstract

Hawai‘i’s forest ecosystems are changing rapidly due to a high level of species introductions, and it is an open question whether native species will be maintained. Several studies have explored the potential for native species to succeed in future communities dominated by introduced species in Hawai‘i, but the results have been conflicting and most of the studies have been limited to relatively young forest (<30 yr old). I surveyed a remote, 80-yr-old noncommercial plantation on Hawai‘i Island to determine whether any native tree species were able to succeed in the planted forest. I compared abundance and composition of native species in the plantation to that in a relict, native-dominated forest adjacent to the plantation and located on the same substrate type. After 80 yr, native species constituted just 4.5% of basal area and 12.1% of stem density in the plantation. However, I found that the relative success of native species varied strongly by species. Of nine native species encountered in the relict forest, six were rare or absent in the planted forest. A seventh (Metrosideros polymorpha) dominated the relict forest but was unable to recruit in the planted forest. However, two shade-tolerant understory tree species (Psychotria hawaiiensis and Psydrax odoratd) were at least as common in the plantation as in the relict forest, and the latter was significantly more abundant in the plantation. Thus, although I found no evidence that native species will dominate with continued succession, I found that at least two native species may remain important components of plantation-derived Hawaiian forests in the future.