Rain forest vegetation of 'Eua Island, Kingdom of Tonga

The indigenous vegetation of 'Eua Island, Tonga, is described and a species list presented. Quantitative data were collected from 40 forest plots in which all vascular plant species were recorded and the diameters of all stems ≥ 5 cm dbh were measured. Plot classification, based on basal area data, identified six forest types, two coastal and four inland, which reflect an elevational sequence from the coast to the island's summit (312 m a.s.l.). A polar ordination, based on basal area data, arranged plots from the four inland forest types in a sequence from low to high elevation along one ordination axis, and from more mature to less mature along a second axis. Species richness increased with elevation. Several additional, non-forest vegetation types, including fern- and grass-dominated vegetation of inland ridges and shrub-dominated vegetation of cliffs and rocky shores, were sampled semi-quantitatively and are also described.