What is forest?

Abstract

Two main kinds of vegetation cover the surface of Ghana: forest and savanna; these, and the various formations into which they may be subdivided were defined at a Pan-African conference at Yangambi (C.S.A. 1956), and more recently by UNESCO (1973). Forest is dominated by trees at least 5 m high, whose crowns interlock, and lacks a continuous grassy ground layer. The crowns of trees in savanna are separated, or trees may be absent; there is always a seasonally dense understorey of grasses. Taxonomic distinctions are also important. Very few plant species occur naturally in both kinds of vegetation — notable exceptions are the trees Afzelia africana and Diospyros mespiliformis. The grasses which flourish in forest — such as Leptaspis cochleata and Olyra latifolia — are not found in savanna, and the grass tribe Andropogoneae which is so abundant in savanna is absent from forest. Both the Yangambi and the UNESCO classifications recognise a third formation-type — woodland — as intermediate between forest and savanna.