Seedling recruitment correlates with seed input across seed sizes: implications for coexistence

Understanding controls on recruitment is critical to predicting community assembly, diversity and coexistence. Theory posits that at mean fecundity, recruitment of highly fecund small-seeded plants should be primarily microsite limited, which is indicated by a saturating recruitment function. In contrast, species that produce fewer large seeds are more likely to be seed-limited, which is characterized by a linear recruitment function. If these patterns hold in nature, seed predation that disproportionately affects larger-seeded species can limit their establishment. We tested these predictions by comparing recruitment functions among 16 co-occurring perennial forb species that vary by over two orders of magnitude in seed size. We also assessed how post-dispersal seed predation by mice influenced recruitment. We added seeds at densities from zero to three times natural fecundity of each species to undisturbed plots and examined spatial variation in recruitment by conducting experime...