Plant functional traits are thought to drive biomass production and biogeochemical cycling in tropical forests, but it remains unclear how nitrogen (N)‐fixing legumes influence the functional traits of neighbouring trees and forest‐wide biomass dynamics. Further, the degree to which effects of N‐fixers are density‐dependent and may depend on stem size and spatial scale remains largely unknown. Here, we examine 30 years of stem demography data for ~20,000 trees in a lowland tropical forest in Trinidad that span a wide range of functional traits thought to drive above‐ground biomass (AGB) dynamics. These forests show positive but decreasing long‐term net AGB accumulation resulting from constant average productivity but increasing mortality of non‐fixing trees over time. We find that high abundance of N‐fixing trees is associated with compositional shifts in non‐fixer functional traits that confer lower competitive performance and biomass accumulation. Across tree size classes, most interactions between N‐fixers and non‐fixers were negative, density‐dependent, and strongest at smaller spatial scales.
Nitrogen (N)‐fixing trees are thought to break a basic rule of leaf economics: higher leaf N concentrations do not translate into higher rates of carbon assimilation. Understanding how leaf N affects photosynthesis and water use efficiency (WUE) in this ecologically important group is critical. We grew six N‐fixing and four non‐fixing tree species for 4–5 years at four fertilization treatments in field experiments in temperate and tropical regions to assess how functional type (N fixer vs. non‐fixer) and N limitation affected leaf N and how leaf N affected light‐saturated photosynthesis (
- PAR ID:
- 10472173
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- Journal of Ecology
- Volume:
- 111
- Issue:
- 11
- ISSN:
- 0022-0477
- Format(s):
- Medium: X Size: p. 2457-2471
- Size(s):
- p. 2457-2471
- Sponsoring Org:
- National Science Foundation
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Abstract Synthesis . Overall, our findings suggest that local trait‐based interactions between N‐fixing and non‐fixing trees can influence long‐term carbon accumulation in tropical forests. -
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