Future Climate Doubles the Risk of Hydraulic Failure in a Wet Tropical Forest

The Science

A team of researchers found increasing plant water stress from warming temperatures will lead to a future risk of increased tropical forest mortality under climate change. Rising atmospheric carbon levels do not mitigate mortality risk but increase plant productivity. Plant traits are crucial to determining this mortality risk.

The Impact

Tropical forests have significant impacts on global water and carbon cycles. Adapting to global climate change will require an understanding of the change to these crucial resources. Researchers show increasing temperature and drying may increase tropical forest mortality due to increased plant water stress. Increased atmospheric carbon levels were thought to potentially mitigate this loss, but the team’s model shows it does not at these levels of warming. These increasing mortality levels could significantly reduce tropical carbon storage. Global climate change will increase the annual productivity of tropical forests but remove more water from them.

Summary

A team of researchers used a dynamic vegetation model with plant hydrodynamics (FATES-Hydro) to simulate the stand-level responses to future climate changes in a wet tropical forest in Barro Colorado Island in Panama. The team calibrated the model by selecting plant trait assemblages that performed well against Next-Generation Ecosystem Experiments Tropics observations of plant hydrodynamics.

These assemblages were run with temperature and precipitation changes for two greenhouse gas emission scenarios (2086–2100: SSP2-45, SSP5-85) and two carbon dioxide (CO₂) levels (contemporary, anticipated). Simulations show an increase of 5.7% to 10.1–11.3% under future climate scenarios due to increasingly negative leaf water potentials. Gross primary productivity increased 27 to 53% under future climate but decreased (–21% to 8.6%) without rising CO₂. Minimum annual leaf water potential (a measure of plant stress) under contemporary simulations decreased under both future scenarios with anticipated CO₂ and under contemporary CO₂ scenarios (indicating greater plant stress). Trait assemblage members that experienced hydraulic failure had substantially more negative minimum season leaf water potential (–1.376  MPa) than those who did not (–0.815  MPa). Simulation analysis shows plant traits played a more significant role in the risk of hydraulic failure (98%) than climate scenarios or models.

Principal Investigator

Zachary Robbins
Los Alamos National Laboratory
[email protected]

Co-Principal Investigator

Chonggang Xu
Los Alamos 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 research was supported as part of the Next-Generation Ecosystem Experiments Tropics, funded by the Biological and Environmental Research program within the U.S. Department of Energy’s Office of Science.

References