Light, nitrogen supply, and neighboring plants dictate costs and benefits of nitrogen fixation for seedlings of a tropical nitrogen‐fixing tree

The ability to fix nitrogen may confer a competitive advantage or disadvantage symbiotic nitrogen-fixing plants depending on the availability of soil and energy fuel fixation. Understanding these costs benefits fixation is critical predicting ecosystem dynamics nutrient cycling. We grew inoculated (with bacteria) uninoculated seedlings Pentaclethra macroloba (a tree species) both in isolation with Virola koschnyi nonfixing under gradients light assess how activity affect growth, biomass allocation, responses neighboring plants. Inoculation itself did not provide growth fixers, regardless limitation status. Higher rates increased similarly for nitrogen-limited nitrogen-saturated fixers. Nodule production was offset by reduced fine-root resulting no change total belowground allocation associated Under conditions, fixers partially downregulated presence neighbor. These results suggest that can advantage, even reduce minimize facilitation neighbors.