•oki'a Dieback and Protection Management of the Hawaiian Rain Forest

The facts about the ohia (Metrosideros polymorpha) rain forest dieback are put together in abbreviated form as far as they have been revealed over the past 12 years of intensive research in Hawaii. They lead to the conclusion that this native rain forest ecosystem is made up of an irregular and dynamic mosaic of ohia cohort stands occurring side by side. These are in different and similar life stages and successional development. Unlike a multi-species forest with steady-state stand segments, the Hawaiian rain forest appears to break down periodically in larger and smaller stand segments. The primary cause of this breakdown or canopy dieback is considered to be cohort senescence rather than biotic diseases or abiotic environmental fluctuations. The last 2 disturbances are believed to act at secondary levels. The original mosaic, however, is suggested to be largely the result of catastrophic disturbances, which recur rather infrequently on the same site. Recovery following dieback depends largely on the underlying soil-substrate mosaic and the associated species. On nutritionally poor sites, ĥi'a sapling cohorts following dieback have a better chance of developing a second canopy than on nutritionally rich sites where competition of other species is strong. This new knowledge has important implications for protection management, particularly with regard to the design of Hawaiian rain forest preserves. For this, ecosystem criteria referring to the considerations of vegetation dynamics given here and the knowledge gained from a one-time survey of current native forest bird refugia by the U.S. Fish and Wildlife Service should be combined. A number of specific management-related research tasks are suggested, such as mapping an already established physical and chemical habitat classification (at 1:24,000) and superimposing on it the