Observational Studies of Conspecific Negative Density Dependence on Barro Colorado Island, Panama

Explaining how such high numbers of tree species can coexist in tropical forests has long posed a challenge for ecologists. Coexistence is more likely if species have a more negative effect on neighboring individuals of their own species (conspecifics) than of other species (heterospecifics). As result, numerous ecological studies have looked for evidence of such negative effects of conspecific neighbors. Here we review observational studies of conspecific negative-density/distance dependence (CNDD) conducted on Barro Colorado Island (BCI) over the past four decades. Taken together, these studies provide evidence for the widespread existence of CNDD in the BCI tree community. Yet, the studies also reveal that the strength and prevalence of CNDD vary among life stages and species. Future work is needed to quantify the cumulative effect of CNDD across the full life cycle and determine whether CNDD contributes to the maintenance of high tree species diversity in the BCI forest.