Storms are a major source of forest mortality in the Amazon

Extreme storms are an underestimated cause of tree mortality in the Amazon, causing “windthrow” events in which trees are broken or completely uprooted. A team of experts at the Department of Energy’s Lawrence Berkeley National Laboratory has investigated how increasingly intense thunderstorms in a warming climate will affect forest mortality and carbon storage across the Amazon rainforest. 

The researchers determined that by the end of the century, the Amazon will likely experience 43 percent more large windthrow events that affect at least 25,000 square meters of forest. The study fills a major gap in climate models, helping to clarify the link between storm conditions in the atmosphere and forest mortality on land.

“Building this link between atmospheric dynamics and damage at the surface is very important across the board,” said Jeff Chambers, director of the Next Generation Ecosystem Experiments (NGEE)-Tropics project. “It’s not just for the tropics. It’s high-latitude, low-latitude, temperate-latitude, here in the U.S.”

“We want to know what these extreme storms and windthrows mean in terms of the carbon budget and carbon dynamics, and for carbon sinks in the forests.”

“It’s a complicated system, and there are still a lot of pieces of the puzzle that we’re working on. In order to answer the question more quantitatively, we need to build out the land-atmosphere links in Earth system models.”  

For the investigation, the researchers compared atmospheric data with a map of more than 1,000 large windthrow events. The analysis revealed that a measurement known as CAPE (convective available potential energy) is a good predictor of major blowdowns. 

“Storms account for over half of the forest mortality in the Amazon,” said study first author Yanlei Feng. “Climate change has a lot of impact on Amazon forests, but so far, a large fraction of the research focus has been on drought and fire. We hope our research brings more attention to extreme storms and improves our models to work under a changing environment from climate change.”

The study is published in the journal Nature Communications.

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By Chrissy Sexton, Earth.com Editor

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