Conspecific negative density dependence and why its study should not be abandoned

Abstract

Recent studies showing bias in the measurement of density dependence have the potential to sow confusion in the field of ecology. We provide clarity by elucidating key conceptual and statistical errors with null-model approaches used in recent studies of density dependence. Importantly, we show that neither a relabeling null model nor a more biologically appropriate null model reproduces differences in density-dependent recruitment between tropical and temperate forests, indicating that the latitudinal gradient in negative density dependence is not an artifact of statistical bias. We also suggest a path forward that combines observational comparisons of density dependence in multiple fitness components across localities with mechanistic and geographically replicated experiments.