'Ohi'a Dieback in Hawai'i: Vegetation Changes in Permanent Plots

Abstract

Approximately 50,000 ha of native '6hi'a (Metrosideros polymorpha Gaud.) forest on the island of Hawai'i experienced a drastic reduction (dieback) of the tree canopy between 1954 and 1977. Concern for the management of this important native ecosystem has stimulated a great deal of research on the Hawaiian dieback phenomenon. In this paper we address the question of changes in the '6hi'a population after an area has experienced dieback. Since 1976, we have established 62 400-m2vegetation sampling plots throughout the dieback and adjacent nondieback forest areas on the island of Hawai'i. The tall tree vigor and '6hi'a seedling and sapling growth were resamp1ed in 26 of these study plots in 1982. The results of the reassessment of the '6hi'a populations indicate that the forest dieback has not spread appreciably since 1977. However, nearly all the plots located in areas that originally experienced a drastic reduction of the tree canopy cover were found to have a large number of '6hi'a seedlings and saplings. Based on this apparent high level of regeneration following the initial canopy loss, we speculate that most of the forest dieback areas will again develop a closed, tall-statured '6hi'a tree canopy.