In audition to wood production services, forest ecosystems play an important role in the mitigation of anthropogenic climate change. However the role of forests as future C sinks is being discussed since there is increasing evidence or a progressive shift from carbon-limited growth to nutrient-limited growth as demonstrated in FACE experiments. The development of mechanistic models. including the main nutrient balance and their relationship with the carbon and water balances. is necessary to evaluate the future response or forests to climate change. In this contribution, we present the first joint evaluation of a coupled C-water-N-P-K model on a large number of biogeochemical measurements collected in fast-growing eucalyptus plantations in Brazil along entire rotations, including trials with variable levels or fertilisation and water availability. We have first adapted the CASTANEA ecophysiological model, primarily designed for temperate and boreal forests, to the simulation of carbon and water fluxes in tropical Eucalypt. Then, the N,P,K fluxes and stocks within the plant were modelled based on process from the literature and calibrated on specific measurements, including the interaction between nutrient content of organs and carbon and water related processes. The final objective is to quantify the relative importance ,if single nutrients and water limitation on stand growth and carbon productivity, and evaluate the impact of climate change on these different cycles through a change in mean temperature. CO2 concentration and precipitation regime.