TROPICAL RAIN-FOREST TYPES AND SOIL FACTORS IN A WATERSHED AREA IN GUYANA

An inventory was made of the vegetation and soils of a watershed area of 480 ha in the tropical rain forest of Guyana. 252 plots of 0.05 ha were sampled. In total 111 tree species greater-than-or-equal-to 20 cm were recorded. A TWINSPAN analysis resulted in seven groupings. Corre spondence Analysis revealed that the major environmental differentiati on underlying the floristic variation is according to soil type. Final ly, five main forest communities were described. Most sites in the wat ershed area are characterized by the dominance of one or a few species . Species distribution patterns are strongly determined by soil type a nd drainage class.