NUTRIENT GRADIENTS AND SPATIAL STRUCTURE IN TROPICAL FORESTS - A MODEL STUDY

We studied the competitive relationships between two life history strategies of tropical trees in a mixed-age spatial model. The two life histories differ primarily with respect to longevity, biomass per unit nutrient and amount of nutrients shedded. We show that stable coexistence in a homogeneous environment is not feasible, but that both types represent a climax vegetation on appropriate soils. In a smooth gradient of soil nutrient content a sharp transition occurs between the two tree types. The most important factors determining the outcome of the competition are longevity and the presence or absence of disturbance, and not, as earlier assumed, the differences in nutrient hoarding.