Plant Colonization of A Volcanic Island, Surtsey, Iceland

Abstract

Surtsey is the newest member of a group of islands named Vestmannaeyjar (Westmann Islands) off the southern coast of Iceland. All the islands are of volcanic origin with palagonite tuff or basaltic lava. The eruption, which gradually built up Surtsey, started on 14 November 1963 and lasted over 3.5 yr. The island reached the size of 2.7 km². In the spring of 1964 the first biological observations were performed on the island and the vascular plants have been investigated annually since 1965, when the first plant was discovered growing on Surtsey.

The investigation of colonization of vascular plants on Surtsey involves the study of source of available species, means of dispersal, types of habitats on the island, and performance of the plants. The amount of plant material dispersing to Surtsey is in reverse proportion to the distance to the source of available plants, the nearest one being a rock 5.1 km away, but from the mainland the distance for dispersal is over 35 km. The Surtsey ecosystem is still immature and only pioneer organisms are present. By 1986 about 23 species of vascular plants have been recorded growing there and only a few coastal species have become successful colonizers. The sandwort Honkenya peploides has been the most prolific. In 1978, it showed a tendency towards the formation of an association with lyme grass, Elymus arenarius, and later with lungwort, Mertensia maritima. A study of the establishment of vegetation by pioneers in such a naturally barren land could shed some light on problems concerning rehabilitation of devastated areas.