Gold mining causes long-lasting damage in the Amazon rainforest

A recent study has found that efforts to restore forests in the Peruvian Amazon after gold mining are failing – not only because of toxic soil, but because the land has lost its water.

A popular method called suction mining reshapes the landscape so dramatically that it strips away moisture and traps heat, creating extreme conditions that young trees cannot survive.

The study was led by Abra Atwood of the Woodwell Climate Research Center, alongside collaborators from Columbia University, Arizona State University, and Peru’s Universidad Nacional de San Antonio Abad del Cusco.

A dry and damaged landscape

These findings help explain why reforestation in Peru’s Madre de Dios region has seen little success.

One of the co-authors, Josh West, a professor of earth sciences and environmental studies at USC Dornsife College, has spent years examining the effects of mining on ecosystems.

“We’ve known that soil degradation slows forest recovery,” he said. “But this is different. The mining process dries out the land, making it inhospitable for new trees.”

The researchers studied two abandoned Amazon mining sites in Madre de Dios, near the borders of Brazil and Bolivia.

Using drones, underground imaging, and soil sensors, they tracked the effects of suction mining – a technique often used by small-scale or family-run miners. In this method, water cannons blast soil apart, and the resulting slurry is filtered to extract gold.

No topsoil, no forest

The powerful streams also carry off the nutrient-rich topsoil. What’s left behind are still ponds and massive sand piles, sometimes up to 30 feet tall.

Unlike excavation mining, which can leave parts of the topsoil intact, suction mining strips the land bare. This not only removes vital nutrients but also changes how water behaves in the soil.

To investigate this, the team used electrical resistivity imaging, a technique that measures how moisture travels underground.

The researchers discovered that water drains through the sand piles as much as 100 times faster than in untouched forest soil. These piles also lose water about five times faster after rainfall.

Amazon heat stops forest recovery

To better understand the conditions in deforested areas, the scientists placed sensors across various environments – sand and clay zones, pond edges, and natural forests.

The results were consistent: areas in the Amazon impacted by suction mining were hotter and drier. On exposed sand piles, ground temperatures reached up to 145°F (60°C), far higher than in shaded forest areas.

“It’s like trying to grow a tree in an oven,” West said. Thermal imaging from drones showed how barren areas absorb and radiate heat, while nearby forests and pond edges remained cooler. Without moisture or shade, young trees have little chance to survive.

“When roots can’t find water and surface temperatures are scorching, even replanted seedlings just die,” Atwood said. “It’s a big part of why regeneration is so slow.”

Gold rush worsens deforestation

Despite some regrowth near ponds and in low-lying areas, the team found that much of the land – especially where sand piles dominate – remains barren.

These spots are far from the water table and lose moisture quickly, making reforestation extremely difficult.

From 1980 to 2017, small-scale gold mining wiped out over 95,000 hectares of rainforest in Madre de Dios – an area more than seven times the size of San Francisco.

Even today, operations are expanding around the Tambopata National Reserve, posing serious risks to biodiversity and nearby Indigenous communities. Across the wider Amazon basin, gold mining now contributes to nearly ten percent of deforestation.

Trees alone can’t heal the Amazon

To improve recovery efforts, the scientists suggest going beyond planting trees. One proposed solution is reshaping the land itself – flattening sand piles and filling in ponds to bring new roots closer to underground water sources.

This could help retain moisture and improve survival rates for new vegetation. Though natural erosion could eventually help, the researchers stress that it’s happening far too slowly to match the urgency of the crisis.

“There’s only one Amazon rainforest,” West said. “It’s a living system unlike anything else on Earth. If we lose it, we lose something irreplaceable.”

The experts hope their findings will guide new strategies to restore life to damaged parts of the Amazon. Without dramatic changes to current practices – and a commitment to reshape the land, not just replant it – millions of acres may remain lost to gold and drought.

The study is published in the journal Nature Communications Earth & Environment.

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