The Vegetation of Tristan Da Cunha

Abstract

Tristan is a Tertiany volcanic island 12 km in diameter and 2060 m high, with a temperate oceanic climate. It has been settled since 1810. Vegetational formations described are: On Lowland Plains (0-50 m): Strand and Blown Sand communities; Pasture grassland; Peat mires. On Cliffs (0-300 m): Scree communities; Blechnum penna-marina sward; Phylica arborea scrub; Blechnum palmiforme scrub; Grassland. On Base (plateau at 300-900 m): Phylica arborea bush; Blechnum palmiforme scrub; Empetrum rubrum heath; Peat Mires. On Peak (900-2060 m): Rumex acetosella grassland; Rhacomitrium - Empetrum heath; Alpine desert and Cinder scree. About 60 species of vascular plants are native to the island, more have been introduced since human settlement. Native vegetation has been altered by elimination of lowland Phylica bush, reduction of Tussock grasses and Phylica on the cliffs, and establishment of Rumex acetosella grassland on the Peak. Extreme poverty of the flora due to dispersal difficulties leads to high ecological amplitude of many species and difficulty of describing vegetation floristically. Physiognomic comparisons show resemblances of vegetation to O. Pico, Hawaii, Mt. Elgon and Fernando Po.