Functional groups, species, and light interact with nutrient limitation during tropical rainforest sapling bottleneck

1. Potential variability in nutrient limitation among tree size classes, functional groups, and species calls for an integrated community- and ecosystem-level perspective of lowland tropical rainforest nutrient limitation. In particular, canopy trees determine ecosystem nutrient conditions, but competitive success for nutrients and light during the sapling bottleneck determines canopy composition. 2. We conducted an in situ multi-nutrient sapling fertilization experiment at La Selva Biological Station, Costa Rica, to determine how functional group identity, species identity, and light availability can impact nutrient limitation of stem growth in three functional groups and nine species. 3. Despite high soil fertility, we found nutrient-light limitation in two functional groups and four species. Unexpectedly, the nitrogen-fixing (“N2fixers”) and shade-tolerant functional groups were significantly nutrient limited, while the light-demanding functional group was not. 4. This was partially ...