Development of the ecosystem on surtsey with references to Anak Krakatau

There is a strong similarity in the formation and size of the two new volcanic islands: Anak Krakatau, Indonesia (emerging 1930) and Surtsey, Iceland (emerging 1963). They are both piled up from an ocean floor of over 100 m depth, forming islands of cinder and lava covering more than 2 km² in area. They are both extremely valuable for various ecological studies, ie of investigation of means of dispersal and colonization. However, due to their tropical and subarctic locations, respectively, there is an extreme difference in climate of the two islands and thus in the kind of available life forms, their means of colonization and rate of growth.The first vascular plant was found on Surtsey in 1965, bryophytes became established in 1967 and lichens were first detected in 1970. The advancement of the vascular plant colonization has been of greatest importance in the establishment of vegetation on the island. Twenty-five species of vascular plants, all herbaceous, had been recorded on Surtsey in 1990, the dominant species being Honkenya peploides. Less than 1% ofthe island has vegetation cover, root biomass is low and the organic carbon and nitrogen status of the soil is poorly developed. Birds started nesting on Surtsey in 1970 and six species, all depending on marine life for food, had nested on the island in 1990. The land-invertebrate fauna has developed slowly on Surtsey and the island is devoid of vertebrates other than birds.