Wood Density Does Not Affect Leaf-Level Water-Use Efficiency

The Science

A team of researchers investigated how the density of wood in trees—a proxy for successional stage—related to their water-use efficiency (WUE). Leaf-level WUE is a measure of how much water plants need for photosynthesis. The study focused on trees in an Amazonian rainforest, comparing early successional (low wood density) and late successional (high wood density) species. Researchers measured gas exchange in tree leaves to understand how they regulate water loss and carbon uptake.

The Impact

This research provides insight into the complex relationship between plant traits and WUE. It challenges previous work suggesting leaf-level WUE differs between early successional and late successional species and suggests a simpler approach to parameterization is possible for representation of tropical forest WUE in land surface models.

Summary

This study aimed to determine if wood density influences leaf-level WUE in an Amazonian wet tropical forest. Steady-state gas exchange measurements were performed on top-of-canopy leaves in early and late successional species. Contrary to expectations, the study found stomatal control of transpiration and carbon assimilation was similar. Both types of species had similar dark respiration rates and nitrogen contents. However, early successional species invested more nitrogen in photosynthetic capacity and exhibited higher photosynthetic rates and stomatal conductance. This work provides important information for parameterization of fast-growing, light-demanding, early successional species and slow-growing, shade-tolerant, late successional species in land surface models.

Principal Investigator

Alistair Rogers
Brookhaven National Laboratory
[email protected]

Program Manager

Brian Benscoter
U.S. Department of Energy, Biological and Environmental Research (SC-33)
Environmental System Science
[email protected]

Funding

This work was supported by the Next‐Generation Ecosystem Experiments Tropics Project that is funded by the Biological and Environmental Research program in the U.S. Department of Energy’s (DOE) Office of Science and through DOE’s contract No. DE-SC0012704 to Brookhaven National Laboratory.

References