U.S. Department of Energy Office of Biological and Environmental Research

BER Research Highlights


Vulnerability of Amazon Forests to Storm-Driven Tree Mortality
Published: May 03, 2018
Posted: July 02, 2018

Wind-related tree mortality is important for reliable prediction of tropical forests and their effects on the Earth' system.

The Science
Researchers from the NGEE-Tropics team found that wind-related tree mortality driven by storms (windthrows) are common in the Amazon region extending from northwest (Peru, Colombia, Venezuela, and west Brazil) to central Brazil, with the highest occurrence of windthrows in the northwest Amazon. More frequent winds, produced by more frequent severe convective systems, in combination with well-known processes that limit the anchoring of trees in the soil, help to explain the higher vulnerability of the northwest Amazon forests to winds.

The Impact
The higher frequency of windthrows in the northwestern Amazon (NWA) may have resulted in a forest that is more adapted to these disturbances with respect to the central Amazonia (CA). Increases in the occurrence of windthrows may produce a shift in composition in CA but not in NWA.

Summary
Tree mortality is a key driver of forest community composition and carbon dynamics. Strong winds associated with severe convective storms are dominant natural drivers of tree mortality in the Amazon. Why forests vary with respect to their vulnerability to wind events and how the predicted increase in storm events might affect forest ecosystems within the Amazon are not well understood. We found that windthrows are common in the Amazon region extending from northwest (Peru, Colombia, Venezuela, and west Brazil) to central Brazil, with the highest occurrence of windthrows in the northwest Amazon. More frequent winds, produced by more frequent severe convective systems, in combination with well-known processes that limit the anchoring of trees in the soil, help to explain the higher vulnerability of the northwest Amazon forests to winds. Projected increases in the frequency and intensity of convective storms in the Amazon have the potential to increase wind-related tree mortality. A forest demographic model calibrated for the northwestern and the central Amazon showed that northwestern forests are more resilient to increase in wind-related tree mortality than forests in the central Amazon. This study emphasizes the importance of including wind-related tree mortality in model simulations for reliable predictions of the future of tropical forests and their effects on the Earth system.

Contacts (BER PM)
Daniel Stover
SC-23.1
Daniel.Stover@science.doe.gov (301-903-0289)

Dorothy Koch
SC-23.1
dorothy.koch@science.doe.gov (301-903-0289)

(PI Contact)
Jeffrey Q. Chambers, Lawrence Berkeley National Laboratory
jchambers@lbl.gov

Funding
This research was supported as part of the Next Generation Ecosystem Experiments-Tropics and the Regional and Global Climate Modeling, both funded by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research.

Publications
Negron-Juarez, R., et al., “Vulnerability of Amazon forests to storm-driven tree mortality.” Env. Res. Lett. 13 054021 (2018). [DOI: 10.1088/1748-9326/aabe9f]

Topic Areas:

  • Research Area: Earth and Environmental Systems Modeling
  • Research Area: Terrestrial Ecosystem Science
  • Research Area: Next-Generation Ecosystem Experiments (NGEE)

Division: SC-23.1 Climate and Environmental Sciences Division, BER

 

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