In the coming decades, a large fraction of the tropical rainforests will be fragmented into remnants surrounded by secondaryvegetation, land-used areas, or roads. It is important to developintegrative tools to monitor the evolution of these fragmentedecosystems. We used the individual-oriented and process-basedforest growth simulator Formind to investigate the spatial andtemporal effects of various intensities and patterns offragmentation within a forest landscape, on standing biomass andfunctional diversity. The simulator was calibrated for anold-growth rain forest in French Guiana, South America. We foundthat the standing biomass of forest remnants was reducedsignificantly compared to a similar area of non fragmented forest.When fewer but large remnants were created rather than many smallones, the total loss in biomass and the increase in the abundanceof early successional species were significantly reduced,confirming that edge effects dominate the functioning of forestremnants. We also performed simulations of secondary successionafter the landscape had been abandoned. The simulated recoverytime in those secondary forests depends on both the size ofcleared area and on the spatial pattern of the remnant forests.