A New Threat for Tropical Forests

A new gold rush could spell big trouble for South American tropical forests, a new study finds.
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A rainforest in Ecuador. (Photo: Elena Kalistratova/Shutterstock)

A rainforest in Ecuador. (Photo: Elena Kalistratova/Shutterstock)

A modern gold rush is underway in South America. While deforestation caused by agriculture, cattle ranching, and urban expansion have all begun to slow in the region, accelerated mining poses a new threat to tropical forests. A new study, published in Environmental Research Letters, identifies a link between the 2007 global economic crisis and gold mining-driven deforestation in South America.

The study looked at an area of lowland tropical and subtropical forest that stretched across at least nine South American countries, including Colombia, Venezuela, Ecuador, and Peru. Mining of gold and other metals has been a problem in the Andes for some time, but gold mining in the lowlands wasn't profitable until the economic crisis when the global demand for gold skyrocketed. The price per ounce shot up to an all-time high of nearly $2,000 in 2011, up from just $250 in 2000.

At the 61 mining sites identified between 2001 and 2006, approximately 377 square kilometers of tropical forest were lost. From 2007 to 2013, the number of mining sites had grown to 116; the area of forest lost: roughly 1,303 square kilometers.

“As soon as gold went over $1,000 an ounce, places that were previously not even considered for gold mining because it wasn’t economically feasible, became feasible,” says Mitchell Aide, a biology professor at the University of Puerto Rico and principal author on the study. Today, the price of gold has settled near $1,200 per ounce, high enough to sustain the surge in lowland gold mining.

Combining data from mining databases with forest cover maps produced by NASA, the authors found that at the 61 mining sites identified between 2001 and 2006, approximately 377 square kilometers of tropical forest were lost. From 2007 to 2013, the number of mining sites had grown to 116; the area of forest lost: roughly 1,303 square kilometers.

“The footprint [of gold-mining] is much bigger than just the area of forest that’s lost,” Aide adds. To get at gold in the lowlands, the forest is razed to make way for mining pits, roadways, and miner settlements. Miners then blast away the surface soil, with what is essentially a big fire hose, and process the run-off with harsh chemicals to extract gold from the slurry.

“A lot of this is happening around or within protected areas in the tropical lowland forest,” Aide says. And those chemicals spread far beyond the mining sites through waterways and the air, polluting one of the world's most biologically rich regions. It takes much longer for a forest to regenerate after mining activities than it would from other anthropogenic uses.

Many species of plants and animals in the area aren’t found anywhere else in the world. “In the areas where the copper and gold deposits are situated, there is a higher rate of endemism that negates any possibility whatsoever of 'recovery'” says Kelly Swing, a professor of environmental science at the Universidad San Francisco de Quito. Ecuador may house as much as 15 percent of all species on the planet, and is still home to uncontacted tribes, Swing notes, all of which are threatened by rapidly growing mining industries. “Ecuador in particular is about to embark on a path of tremendous ‘death and destruction,” Swing says.

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