The Colonization of a New Island

As soon as the first land emerges, some life form invariably finds it. But, the earliest colonists of Anak Krakatau were doomed as the island itself slid back into the sea. Indeed, several times since the present island was established in 1931, the developing vegetation has been eliminated or severely damaged by the eruptions. Yet despite this, many species of plants and animals have colonized the islands, and extensive food webs of plant feeders, predators, detritus feeders and scavengers have developed.

It is convenient to divide the vegetation into two types: the coastal strand-line communities and those of the interior. As the plants themselves are mostly known by their Latin names, this account will mention few by name! Coastal plants are typically sea-dispersed, and often have light buoyant husks that aid flotation, like the coconut (Cocos nucifera) or the sea-almond (Terminalia catappa). The vegetation consists, in this region, of a fairly predictable set of hardy coastal trees, shrubs and beach creepers like the beach morning glory (Ipomoea pes-caprae). Indeed, pretty much the same assemblage of these plants can be found on each of the Krakatau islands, as on other beaches in the Sunda Strait. These species seem to need no obvious site-preparation but can establish in the sand -- in this case a black volcanic sand -- at the back of the beach, where their fruits and seeds are cast by high tides and storm surges.

In the early decades, most of the vegetation of Anak Krakatau was restricted to the beaches and to two or three lobate forelands, mostly having been created by beach accretion. The volcanic cone, in its various evolutionary stages, has been a fairly hostile environment for plant life. The combination of lack of water in the upper well-drained tephra/ash layers in the dry season and the great geothermal heat, and frequent outpourings of polluting gases and ashes may account for the slow pace of inward colonization. However, along the coastal fringes, and a strip of a few scores of meters width at the base of the eastern, more gently shelving side of the island, the succession really began to take off from the late 1970s and throughout the 1980s.