Small-scale gold mining is a major cause of deforestation in the Amazon, and researchers found that in Guyana it destroys dung beetle communities and prevents their recovery for decades.
Gold mining causes 90% of the deforestation in the Guiana Shield, which contains a quarter of the Amazon rainforest as well as large gold deposits, according to a recent study. Most of the gold mining in this region, including in Guyana, is artisanal, driven by small-scale mining rather than large industrial mines.
To understand the long-term “ecological legacy” of such mining, a team of researchers measured dung beetle communities at 16 abandoned small-scale gold mine sites in northwest Guyana. They choose dung beetles, because the insects are easily sampled and play key roles in rainforest functions like nutrient cycling, seed dispersal and pollination. For control, the team monitored dung beetle communities at five nearby intact forests.
At every mining site, the researchers sampled dung beetles at three locations: the center of the mine where vegetation was regrowing, at the edge where the mine met the forest, and about 100 meters (328 feet) away into the forest. They trapped dung beetles using human feces as bait.
Study lead author Sean Glynn from the University of Kent, U.K., told Mongabay by email that because they were camping remotely, they didn’t have reliable access to feces from other animals to use as bait, “however, human seems to always be the best.”
The team also recorded air temperature and vegetation structure at each of the mining and control forest sites.
In total, the researchers collected 8,187 dung beetles from 44 species. They found that both dung beetle numbers and diversity increased as you moved away from the center of mining activity, with the most dung beetles in the control sites.
The team didn’t find any “discernible recovery trend” of the dung beetle communities at mined sites, even two decades after they were abandoned. At the same time, the mine centers had higher temperatures and reduced canopy cover than the other sampled sites.
The team said the findings suggest that “severely degraded soils, disrupted seed banks, and altered microclimates” from mining may prevent the recovery of forest structure critical for dung beetle habitat.
Glynn said while some research shows that planting trees is effective, more needs to be done to understand what can “improve and speed up the recovery of vegetation that will then enable biodiversity to return to these sites.”
Trond Larsen, a dung beetle expert not associated with the study from the NGO Conservation International, told Mongabay that dung beetles can be effective bioindicators to understand environmental impacts.
“We can’t measure everything,” he said. “Dung beetles represent ideal cost-effective indicators that can help us understand patterns of biodiversity loss in response to human disturbance, including gold mining, which poses a rapidly increasing threat to tropical forests.”
Banner image: Oxysternon festivum, the most common dung beetle found in the study. Image by Tom Murray via iNaturalist (CC BY-NC 4.0).
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