This identification work is important, because “the estimation of the number of tree species is essential to guide efforts to conserve, improve, and prioritize the world’s forests,” this work emphasized.

They were published Monday in the Journal of the US National Academy of Sciences (PNAS). Dozens of scholars participated.

>> Tree species richness estimates at the biome level:

Estimated number of tree species in terrestrial biomes for each continent as a color gamut from low richness (yellow) to high richness (red). [Roberto Cazzolla Gatti et al. – PNAS]

About 64,100 tree species have already been listed but according to These functions — whose estimates are based on a more complete database and a more advanced statistical method than before — the total number of species would be around 73,300, or 14% more.

This means that about 9,200 species have yet to be discovered.

>> Read also: Granting a legal status to natural places in order to better protect them

Tropical or subtropical rainforest

Overall, about 43% of all species are found in South America, followed by Eurasia (22%), Africa (16%), then North America (15%) and Oceania (11%), according to the study.

The research team estimates that half to two-thirds of all known species are found in tropical or subtropical rainforests on five continents. Thus a large proportion of species still to be identified should be found in these areas, where fewer surveys are conducted.

In addition, almost a third of the world’s species are classified by scientists as rare and sparsely populated and are found in limited areas. Thus, these species are more at risk of extinction.

>> Distribution of species richness between continents:

Estimates of the percentage of continental epidemics compared to the estimated richness of each continent and intercontinental species (numbers in overlapping groups). In the middle, the percentage of species common to the five continents. [Roberto Cazzolla Gatti et al. – PNAS]

South America has the highest percentage (49%) of endemic species, that is, found only on this continent: “These results confirm the poor diversity of tree species in the world,” write the study authors, particularly in the face of “human land use and future climate.”

“Loss of forest areas containing these rare species will have a direct and potentially long-term impact on global species diversity, and their contribution to ecosystem services,” the biologists added.

Species surveys are a very long-term work and present many challenges, particularly access to certain areas or even consistency of identification, since many botanists, for example, can characterize the same species slightly differently.

>> Read also: A biologist wants to grow the idea of ​​a primitive forest in Western Europe

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