Light-Gap Disturbances, Recruitment Limitation, and Tree Diversity in a Neotropical Forest

TLDR

Light gap disturbances have been postulated to play a major role in maintaining tree diversity in species‑rich tropical forests. This hypothesis was tested in more than 1,200 gaps in a tropical forest in Panama over a 13‑year period. Although gaps increased seedling and sapling densities, the effect was nonspecific, species richness per stem remained unchanged between gaps and controls, spatial and temporal variation in gap dynamics did not explain richness patterns, gap species composition was unpredictable even for pioneers, and strong recruitment limitation decouples gap disturbance from tree diversity control.

Abstract

Light gap disturbances have been postulated to play a major role in maintaining tree diversity in species-rich tropical forests. This hypothesis was tested in more than 1200 gaps in a tropical forest in Panama over a 13-year period. Gaps increased seedling establishment and sapling densities, but this effect was nonspecific and broad-spectrum, and species richness per stem was identical in gaps and in nongap control sites. Spatial and temporal variation in the gap disturbance regime did not explain variation in species richness. The species composition of gaps was unpredictable even for pioneer tree species. Strong recruitment limitation appears to decouple the gap disturbance regime from control of tree diversity in this tropical forest.