Simulating the Long-term Response of Tropical Wet Forests to Fragmentation

In the coming decades, a large fraction of the world’s tropical forests will be fragmented into rem-nants surrounded by secondary vegetation, land-use areas, or roads. It is important to develop inte-grative tools to monitor the evolution of these fragmented ecosystems. We used the individual-oriented and process-based forest growth simulator FORMIND2.0 to investigate the spatial and temporal effects on standing biomass and functional diversity of various intensities and patterns of fragmentation within a forest landscape. The simulator was cali-brated for an old-growth wet forest in French Gui-ana, South America. We found that the standing biomass of forest remnants was reduced signifi-cantly compared to a similar area of nonfragmented forest. When fewer but larger remnants were cre-ated rather than many small ones, the total loss in biomass and the increase in the abundance of early-successional species were significantly reduced, confirming that edge effects dominate the function-ing of forest remnants. We also performed simula-tions of secondary succession after the landscape had been abandoned. The simulated recovery time in those secondary forests depends on both the size of cleared area and the spatial pattern of the rem-nant forests. Key words: edge effects; fragmentation; French Guiana; forest growth model; tropical forest; sec-ondary succession; spatially explicit simulation