Forests in the Peruvian Amazon are not growing back after gold mining—and not just because toxic metals damage the soil, but, crucially, because the land has been depleted of its water. That is according to new findings published in Communications Earth & Environment, revealing that a standard method of mining – known as suction mining, which reshapes terrain to drain moisture and trap heat, has created harsh conditions where replanted seedlings cannot survive.
“We’ve known that soil degradation slows forest recovery,” according to Josh West, professor of Earth sciences and environmental studies at the USC Dornsife College of Letters, Arts and Sciences: “But this is different. The mining process dries out the land, making it inhospitable for new trees,” West said, also a National Geographic Explorer.
Led by Abra Atwood, a scientist at the Woodwell Climate Research Center and former student of West, Atwood worked with colleagues from Columbia University, Arizona State University and Peru’s Universidad Nacional de San Antonio Abad del Cusco to study two abandoned gold mines in Peru’s Madre de Dios region, near the Brazil and Bolivia.
Using drones, soil sensors, and underground imaging to understand how suction mining reshaped lands, the research team found that, unlike the excavating mining used in other parts of the Amazon, suction mining leaves little behind to support new growth.
“It’s like trying to grow a tree in an oven,” West said, adding that drone-mounted thermal cameras showed how barren ground baked under the sun from nearby forested areas and pond edges was significantly cooler. “When roots can’t find water and surface temperatures are scorching, even replanted seedlings just die,” said Atwood. “It’s a big part of why regeneration is so slow.”
Although the team observed some regrowth near pond edges and low-lying areas, large swaths of land remained bare, especially when sand piles were widespread. These spots, which are farther from the water table and lose moisture quickly, are harder to reforest.
Between 1980 and 2017, small-scale gold mining destroyed more than 95,000 hectares—an area more than seven times the size of San Francisco—of rainforest in the Madre de Dios region. In and around the Tambopata National Reserve, operations continue to expand, threatening biodiversity and Indigenous lands. Across the Amazon, gold mining now accounts for nearly 10% of deforestation.
As a result, researchers suggest that recovery efforts could benefit from reshaping the terrain. Flattening the mining sand piles and filling in abandoned ponds could bring tree roots closer to groundwater, improve moisture retention, and boost regrowth. While natural erosion may eventually do the same, the process is far too slow to meet urgent reforestation needs. “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.”
- For more information, click here to find out why Gold Mining amongst the fastest growing causes of deforestation in tropical forests – with a new report published by the World Resources Institue (WRI) revealing that 1.4 million hectares of forests, an area the size of Montenegro, was lost to the extraction of coal, iron and industrial minerals for the 20 years to 2020.
