The Influence of Fertilization on Some Aspects of Succession in a Humid Tropical Forest

Vegetation biomass, nutrient content, and species composition were measured during the first year following clear—cutting of a humid tropical forest near Turriabla, Coast Rica (83°40'W, 9°50N). On some plots regrowth was experimentally manipulated by fertilization and/or by establishment of a monoculture of a successional tree (Cecropia obtusifolia Bertol.). Successional tree plots produced highest biomass and had highest nutrient standing crop 1 yr after cutting; neither biomass nor nutrient standing crop was strongly affected by fertilization on these plots. Plots allowed to regenerate naturally were dominated by forbs on fertilized plots and by shrubs and trees on unfertilized plots. Forb—dominated plots produced the lowest biomass and had the lowest nutrient standing crop. Thus, biomass and vegetation nutrient standing crop were not enhanced by fertilization. Rather, fertilization retarded succession by enhancing the competitive ability of 1 forb species.