A COMPARISON OF THE VEGETATION COMMUNITIES FROM THE ISLANDS OF THE PITCAIRN GROUP

The vegetation of the raised coralline Henderson Island and Oeno Atoll (Pitcairn Group, south-central Pacific Ocean) is described from cover -abundance values of the vascular flora sampled in 10 x 10 m quadrats. Exploratory data analysis by detrended correspondence analysis and tw o-way indicator species analysis was used to summarize the resulting d ata matrices for each island, and to aid definition of vegetation type s. For Henderson, six major vegetation communities are described, whic h are often closely linked to geomorphology: beachfront, embayment for ests, open limestone scrub, cliff and ledge, exposed cliff top, and pl ateau forests. For Oeno, four main vegetation communities are describe d: open sandy littoral, Argusia scrub, closed forest, and coconut grov e. For each island, the main vegetation types were further subdivided into a number of communities depending on the proportions of various t axa Brief qualitative descriptions of the vegetation of Ducie and Pitc airn are also given. Anthropogenic communities, some of which are high ly invasive, are widespread on Pitcairn. Adequate conservation measure s must be given to all islands in the Pitcairn Group; this will protec t not only the endemic-rich and possibly unique plateau forests of Hen derson, but also the species-poor and scientifically important analogu es of vegetation types which occur elsewhere in the Pacific islands. ( C) 1995 The Linnean Society of London