Simulation of the dynamics of nutrients and moisture in tropical ecosystems

Abstract

In tropical rain forests, tree growth is often limited by scarcity of nutrients. For the study of the effects of nutrients and moisture on growth, the use of models is almost compulsory. The main output of the models discussed, NUTCYC and DYNAMITE, is the growth of forest vegetation and, in case of shifting cultivation, also the yields of agricultural crops. State variables, water and nutrient flows, nutrient uptake, growth of the vegetation and required input data are shortly described. Sensitivity analysis identified retranslocation of nutrients in the vegetation as one of the major growth determining processes. As a demonstration of the use of such models, rice yields are calculated that can be expected under various shifting-cultivation scenarios. Finally the models are briefly evaluated, and some questions are discussed that arose when the models were developed.