One in two tree species in the Amazon could be endangered. The Amazon Tree Diversity Network international consortium, which includes the IRD, has just revealed in the Science Advances journal that, according to the predicted deforestation scenarios, 36% to 57% of Amazonian species are at risk of disappearing, i.e. up to 8,700 species out of the 15,000 estimated during the first inventory of the Amazonian Basin, published two years ago.

According to these results, when considered at the scale of the planet, it is feared that 40,000 tropical tree species may be exposed to a risk of extinction and that the proportion of endangered plants on the planet has increased to one fifth.

One in two tree species could disappear due to deforestation in the Amazon. This has just been revealed by a vast international study published in the Science Advances journal, involving nearly 160 scientists, including IRD researchers, assembled under the banner of the Amazon Tree Diversity Network.

Red alert for 8,700 tree species

According to the criteria of the International Union for Conservation of Nature (UICN) -- the most commonly used to determine the conservation status of any species -- the research team believes that 36% to 57% of Amazonian tree species are threatened with extinction, i.e. up to 8,700 species, including the famous Brazilian walnut, which has significant economic implications for the countries of the region. To date, only a minute part of these species features on the NGO's red list. Some may even disappear before they can be observed and described… Should these results be confirmed, the amount of endangered plants on the planet would increase to 22%.

Simulating the variation in the population size of each species

In 2013, the research team had already published the first inventory of Amazonian Basin trees in the Science journal. Through statistical calculation, the total number of species had then been estimated at 15,000 -- compared to the 12,000 identified to date on the planet. This initial inventory also helped assess the distribution area and number of individuals per species. In the new study, the researchers modelled the variation in the population sizes of each species, based on the different deforestation scenarios identified.

Destruction of up to one third of the forest by 2050

With the construction of dams and mines, forest fires and droughts increased by climate change, etc., the Amazon forest is facing a wave of threats. Specialists believe that nearly 20% of the forest has disappeared since the 1970s. By 2050, based on the predicted deforestation scenarios, it should shrink by up to another 30%. In the best case scenario, in which protected areas (national parks, indigenous reservations implemented to reinforce the territorial rights of aboriginal people) would contribute to the preservation of the vegetation, the surface area of the forest will still be reduced by 10%.

This trend can be observed throughout the intertropical zone. The new study claims that some 40,000 tropical tree species across the world could be facing the same risk of extinction.