ABSTRACT
Montane rain forest on a windward slope of Mauna Loa, Hawaii, displays a primary successional sequence on lava flows with ages ranging from 8 years to 9,000 years (Kitayama et al. 1995). Both downy (pubescent) and smooth (glabrous) varieties of the tree Metrosideros polymorpha (Myrtaceae) dominated the upper canopy layers on all lava flows in the age range 50 to 1,400 years. The downy variety was replaced by the smooth variety on the flows more than 3,000 years old. Lower forest layers are dominated a matted fern, Dicranopteris linearis, for the first 300 years, and then by tree ferns (Cibotium spp.). The Cibotium cover declined slightly after 3,000 years, while other native herb and shrub species increased. A ‘climax’ vegetation state was not reached-biomass and species composition changed continuously during succession. Such divergent succession may be unique to Hawaii, where the flora is naturally impoverished and disharmonic due to its geographical isolation (Kitayama et al. 1995). Against this view, it could be argued that Hawaii is the sort of place where succession should have the best chance of following the classical model (R.J.Whittaker pers. comm.). It is very interesting that montane forest on Hawaii does not follow the classical model. Rather, it may be an example of a general pattern of nonequilibrium dynamics of the kind revealed by new work at Glacier Bay and the Krakatau Islands.
