Scientists in Brazil starve trees of water to test Amazon's limits

• Rainforest faces potential tipping point • Experiment cuts rainwater to test resilience • Old-growth trees already dying with drought

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Researcher Ben Hur Marimon Jr. walks over a plastic-covered gutter on a patch of Amazon forest in the Limit Drought experiment in Querência, Brazil, on August 25, 2025.

(REUTERS)

Under Brazil's Amazon rainforest canopy, hundreds of transparent plastic panels hang between tree trunks to starve a hectare of land of half the water it normally receives.

Scientists are creating this artificial drought in Querencia municipality close to the southeastern edge of the world's largest rainforest to better understand the limits of the Amazon's resistance to extreme dry conditions that are predicted by climate change models.

In the experiment, called Seca Limite, or Limit Drought, water is captured by the platforms, then flows through a network of elevated timber gutters before being dumped elsewhere.

Like hospital patients, the vital signs of 61 of the trees are measured, including sap and carbon dioxide flow, respiration and temperature, with solar-powered equipment.

"It's like someone was taking measurements of your pulse and breathing every day," said David Galbraith, a professor of terrestrial ecosystem science at Britain's Leeds University and one of the lead researchers of Limit Drought, as he walked through the wired forest.

The team is also tracking tree trunk size and soil data from six-metre (20-foot) deep holes, while nets capture falling leaves. An artificial intelligence-powered drone has made a 3D model of the forest since the project began late last year.