(49) A Test of the Janzen-Connell Hypothesis using Breadnut (Brosimum alicastrum) Populations in the Chiquibul Rainforest of Belize

     The Janzen-Connell hypothesis seeks to explain the high diversity of tree species in a tropical rainforest by suggesting that seedling mortality resulting from herbivores and pathogens prevents tree recruitment... [ view full abstract ]

     The Janzen-Connell hypothesis seeks to explain the high diversity of tree species in a tropical rainforest by suggesting that seedling mortality resulting from herbivores and pathogens prevents tree recruitment directly beneath parent trees, thus facilitating the establishment of other tree species. Our study tested a premise of this hypothesis by examining the distribution and abundance of Brosimum alicastrum (Breadnut) juveniles as a function of distance from adult trees. We predicted that first year juveniles would show a clustered pattern close to adults in response to seed dispersal, while those older than a year would have higher density away from the parent tree as a result of differential mortality over time. The pattern of juvenile distribution was examined under four adult B. alicastrum trees in the Chiquibul Rainforest of Belize. We found that there was a spatial segregation of age classes among juveniles located beneath parent trees. First-year juveniles were clustered beneath the canopy, while older juveniles were clustered further away, confirming our hypothesis. Belizean rainforests have some of the highest tree diversity in Mesoamerica. Our study adds to the growing body of evidence to suggest that Janzen-Connell effects may be responsible for maintaining this diversity.