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Title: Density-dependent adult recruitment in a low-density tropical tree

The Janzen–Connell hypothesis is a well-known explanation for why tropical forests have large numbers of tree species. A fundamental prediction of the hypothesis is that the probability of adult recruitment is less in regions of high conspecific adult density, a pattern mediated by density-dependent mortality in juvenile life stages. Although there is strong evidence in many tree species that seeds, seedlings, and saplings suffer conspecific density-dependent mortality, no study has shown that adult tree recruitment is negatively density dependent. Density-dependent adult recruitment is necessary for the Janzen–Connell mechanism to regulate tree populations. Here, we report density-dependent adult recruitment in the population ofHandroanthus guayacan, a wind-dispersed Neotropical canopy tree species. We use data from high-resolution remote sensing to track individual trees with proven capacity to flower in a lowland moist forest landscape in Panama and analyze these data in a Bayesian framework similar to capture–recapture analysis. We independently quantify probabilities of adult tree recruitment and detection and show that adult recruitment is negatively density dependent. The annualized probability of adult recruitment was 3.03% ⋅ year−1. Despite the detection of negative density dependence in adult recruitment, it was insufficient to stabilize the adult population ofH. guayacan, which increased significantly in size over the decade of observation.

 
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NSF-PAR ID:
10077311
Author(s) / Creator(s):
;
Publisher / Repository:
Proceedings of the National Academy of Sciences
Date Published:
Journal Name:
Proceedings of the National Academy of Sciences
Volume:
115
Issue:
44
ISSN:
0027-8424
Page Range / eLocation ID:
p. 11268-11273
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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