Deforestation’s impending impact on Amazonian extinctions

The Amazon rainforest is many things: largest rainforest on the planet, home to one million indigenous people, carbon sink helping to alleviate climate change. It is also a biodiversity hotspot providing habitat for 10% of all known species in the world. Sadly, decades of deforestation have jeopardized all of the Amazon’s important functions—a fact that has long been acknowledged—but its effect on extinction may be significantly worse than previously assumed. If all deforestation stopped today, the Amazon would continue losing species. Scientists estimate we’ve yet to experience 80% of the Amazon’s extinctions driven by deforestation. The Amazon is in debt, extinction debt, and we need to pay attention.

Extinction debt is future species loss caused by previous events. In deforestation’s case, cutting down trees does not directly kill off a species, but the resulting reduction in habitat, decreased resource availability, and increased habitat fragmentation eventually do. By destroying more land before the extinction effects of the previous deforestation have time to play out, we rack up an extinction debt. That’s how we’ve cut, burned, and plowed our way to an anticipated 2 mammal, 5 bird, and 1 amphibian extinction on average per 2500 square kilometers (about 965 square miles). We’ve already sentenced an estimated 38 Amazonian species to imminent local extinction, and if we don’t drastically reduce deforestation, nearly all Amazonian species may follow them by the year 2050.

While that devastating fate is possible, it is also preventable. Some scientists encourage focusing on conservation efforts where the projected extinction debt is highest. Others suggest doubling down on Brazil’s Forest Code. The law passed in 1965 with intentions of preserving native plant growth and restoration but has been weakly enforced. There was, however, a decrease in Amazonian deforestation for several years until a recent spike in 2019. We need to encourage the Brazilian government, citizens, and ourselves, —as global consumers of goods produced in the Amazon—to follow the Forest Code, restore Brazil’s natural habitat, and bring down deforestation rates. While forest restoration and regeneration don’t bring about an immediate return of an area’s initial species abundance, by prioritizing the forests, perhaps we can steadily undo some of our debt so the Amazon rainforest may retain its rich biodiversity.

 

Sources:

Sample, Ian. “Amazon’s doomed species set to pay deforestation’s ‘extinction debt.’” The Guardian, 12 July 2012, https://www.theguardian.com/environment/2012/jul/12/amazon-deforestation-species-extinction-debt

Shukman, David. “Brazil’s Amazon: Deforestation ‘surges to 12-year high.’” BBC News, 30 Nov. 2020, Brazil’s Amazon: Deforestation ‘surges to 12-year high’ – BBC News

Thompson, Helen. “Most of Amazon Rainforest’s Species Extinctions Are Yet to Come.” Scientific American, 13 July 2012, https://www.scientificamerican.com/article/most-amazon-rainforest-species-extinctions-yet-to-come/

Wearn, Oliver R., Daniel C. Reuman, and Robert M. Ewers. “Extinction Debt and Windows of Conservation Opportunity in the Brazilian Amazon.” Science, vol. 337, no. 6091, 2012, pp. 228-232.