Tree diversity in tropical rain forests: A validation of the intermediate disturbance hypothesis

The "intermediate disturbance hypothesis," which postulates maximum diversi ty at intermediate regimes of disturbance, has never been clearly proved to apply to species-rich tropical forest tree communities and to local-scale canopy disturbances that modify light environments. This hypothesis was tes ted on a sample of 17,000 trees in a Guianan forest, 10 years after a silvi cultural, experiment that added to natural treefall gaps a wide range of di sturbance intensities. Species richness, standardized to eliminate density effects, peaked at intermediate disturbance levels, particularly when distu rbance intensity was estimated through the percentage of stems of strongly light-dependent species.