More than half of all Amazonian tree species may be globally threatened

Amazonian forests have lost ~12% of their original extent and are projected to lose another 9 to 28% by 2050. The consequences of ongoing forest loss in Amazonia (here all rainforests of the Amazon basin and Guiana Shield) are relatively well understood at the ecosystem level, where they include soil erosion, diminished ecosystem services, altered climatic patterns, and habitat degradation. By contrast, little is known about how historical forest loss has affected the population sizes of plant and animal species in the basin and how ongoing deforestation will affect these populations in the future.

In a new study, published this week in the journal Science Advances, a research team comprising 158 researchers from 21 countries compared data from forest surveys across the Amazon with maps of current and projected deforestation to estimate how many tree species have been lost, and where.

Their results show that 36-57% of the Amazon's estimated 15,000 tree species likely qualify as globally threatened under IUCN Red List of Threatened Species criteria. Because the same trends observed in Amazonia apply throughout the tropics, the researchers argue that most of the world's more than 40,000 tropical tree species likely qualify as globally threatened.

Fortunately, the authors also report that protected areas and indigenous territories now cover over half of the Amazon Basin, and contain sizable populations of most threatened tree species.

This is good news from the Amazon that you don't hear enough of. In recent decades Amazon countries have made major strides in expanding parks and strengthening indigenous land rights. And our study shows this has big benefits for biodiversity.

However, parks and reserves will only prevent extinction of threatened species if they suffer no further degradation. The authors caution that Amazonian forests and reserves still face a barrage of threats, from dam construction and mining to wildfires and droughts intensified by global warming, and direct invasions of indigenous lands.

It's a battle we're going to see play out in our lifetimes. Either we stand up and protect these critical parks and indigenous reserves, or deforestation will erode them until we see large-scale extinctions.