Chisholm and Fung claim that our method of estimating conspecific negative density dependence (CNDD) in recruitment is systematically biased, and present an alternative method that shows no latitudinal pattern in CNDD. We demonstrate that their approach produces strongly biased estimates of CNDD, explaining why they do not detect a latitudinal pattern. We also address their methodological concerns using an alternative distance-weighted approach, which supports our original findings of a latitudinal gradient in CNDD and a latitudinal shift in the relationship between CNDD and species abundance.
Bibliographical noteFunding Information:
We thank an anonymous reviewer for suggesting the distance-weighted approach. We also thank everyone involved in the collection of the vast quantity of data in the CTFS-ForestGEO network; see table S20 in our original paper for site-specific acknowledgments. Supported by NSF grant DEB-1545761 (S.J.D.), NSF grants DEB-1256788 and DEB-1557094 (J.A.M.), NSF grant DEB-1257989 (S.A.M.), and the Tyson Research Center. We declare no conflicts of interest. The data and R code for analyses are available at the Smithsonian Institution’s ForestGEO database portal: https:// forestgeo.si.edu/explore-data and https://forestgeo.si.edu/ plant-diversity-increases-strength-negative-density-dependence-global-scale.
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