The formation of island ecosystems

Abstract

Island ecosystems are formed from the same generic building blocks as continental ecosystems. These can be reduced to five: (1) the terrestrial habitat (soil-parent material and topography), (2) the regional and local climate, (3) the regional biota with differential restrictions of accessibility, (4) the ecological roles assumed by the species including their potential for adaptation, and (5) the overriding dimensions of space and time. Unique to island ecosystems are various limitations that can lead to a peculiar ecology. These do not relate to the first two abiotic components mentioned above, but to the biotic components (3) and (4) and their interaction with space and time. Accessibility of species to the island habitat is a primary limitation that prevents many species of the regional biota from becoming established. This in turn results in further restrictions in the ecological types of species coming together. Limited space puts restrictions on population sizes, and time, together with isolation, is setting limits on the evolution of diversity. The paper gives examples by comparing vegetation processes in the Krakatau islands with those in Hawaii.