Occurrence of Indigenous Plant Species in a Middle-Elevation Melaleuca Plantation on O'ahu (Hawaiian Islands)

Abstract

The occurrence of native species at a middle-elevation (265-290 m) site on the island of O'ahu is of interest because of the extremely disturbed character of the vegetation and paucity of native forest species in the vicinity and at these elevations generally. 'Ohi'a (Metrosideros polymorpha) and native shrubs are understory elements in a plantation of Melaleuca quinquenervia that was planted in the early 1930s. The relatively open character of the stand (light levels underneath the canopy 20-50% of incident radiation) may allow enough penetration of light to the subcanopy for native woody plants while excluding more light-demanding alien taxa. The variety of Metrosideros present is the smooth-leaved form (M polymorpha var. glaberrima) more prevalent in the later stages of succession. The findings presented here may be an example of a tree plantation acting to foster native species and promote forest regeneration, a phenomenon that has been reported in degraded lands elsewhere in the Tropics.