“More than 90% of the deforestation due to gold mining in the tropical humid forests of South America is concentrated in four ecoregions,” Nora Alvarez-Berríos of the University of Puerto Rico, US, told environmentalresearchweb. “These ecoregions are among the most biodiverse regions in the world.”

Gold mining has caused deforestation chiefly in the Guianan moist forest, the Southwest Amazon moist forest, Tapajós-Xingú forest, and Magdalena Valley-Urabá region.

“Given the interconnection of the global demand for gold and local land changes, it is important to evaluate what actions local actors can take to alleviate future pressures related to fluctuations in the global economy and the price of gold,” said Alvarez-Berríos.

Together with colleague Mitchell Aide, Alvarez-Berríos built a database of mine locations and used forest cover maps from satellite images to assess deforestation due to gold mining in tropical and subtropical moist broadleaf forests below 1000 m in Colombia, Venezuela, Guyana, Suriname, French Guiana, Brazil, Ecuador, Peru and Bolivia.

From 2001 to 2006, around 377 square km of forest was lost to 61 gold mining sites; from 2007 to 2013, in contrast, the figure was 1303 square km at 116 sites. In the year 2000 gold cost $250 per ounce while in 2013 it cost $1300; the higher price means it’s more viable to extract gold from low-grade deposits under tropical forests. World gold production increased from around 2445 metric tons in 2000 to roughly 2770 metric tons in 2013.

According to Alvarez-Berríos, a study in review (Graesser et al.) has found a slowdown in deforestation caused by agriculture since the economic crisis.

“We were interested in determining if there were similar trends in deforestation associated with extractive resource activities that are highly vulnerable to fluctuations in the international market,” she said. “Contrary to agricultural expansion, gold-driven deforestation accelerated in this region after the global economic crisis of 2007, and is currently one of the leading causes of forest loss in some of the most important tropical forests in South America.”

Various more active zones of gold-mining deforestation occurred inside, or within 10 km of, 32 protected areas, the team found, even when they had a strict protection designation. “Given that gold-mining activities and biodiversity coincide in space, there is a need to reduce the impacts of gold extraction on the environment,” said Alvarez-Berríos.

Gold mining can pollute water sources and have an impact far from its location, for example, elevating mercury concentrations in humans hundreds of kilometres away. Ecosystems may be affected by increased sedimentation in water bodies, heightened wildlife stress due to mercurial biomagnification, noise pollution, increased hunting and the degradation of vegetation due to various chemical pollutants, according to the team in Environmental Research Letters (ERL).

“Despite recognized environmental and social costs related to gold mining, the fact remains [it] is often an important contributor to the economies of industrialized and developing countries and can be the principal source of income for many needy populations,” said Alvarez-Berríos. “Unfortunately, there is little hope that the gold mine boom will slow down in the near future. Our research can be used as a platform to design other comparative analyses, design regional conservation efforts and plans to minimize gold mining impact on biodiversity.”

Now the team plans to shift the research from a regional to a more local scale, focusing on the Madre de Dios region of Peru. “We are analysing how international gold prices, national mining policies, and local land tenure and access rules are affecting the patterns of gold-mining deforestation,” said Alvarez-Berríos.

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