The Science

Researchers from the Next-Generation Ecosystem Experiments (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 northwestern Amazon (NWA). 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 NWA forests to winds.

The Impact

The higher frequency of windthrows in 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. The team 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 NWA. 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 NWA 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 an 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.

Principal Investigator

Jeffrey Chambers
Lawrence Berkeley National Laboratory
jchambers@lbl.gov

Program Manager

Daniel Stover
U.S. Department of Energy, Biological and Environmental Research (SC-33)
Environmental System Science
daniel.stover@science.doe.gov

Funding

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

References