Earth may have 9,200 more tree species than previously thought

Trillions of trees are growing on Earth, though how many kinds there are has been underestimated, a new study finds.

Earth hosts roughly 64,100 known tree species. But there could be at least 73,300 — about 14 percent more than previously thought — a global collaboration of researchers reports in the Feb. 8 Proceedings of the National Academy of Sciences.

More than a third of the 9,200 undiscovered species are probably rare and hiding out in South America’s biodiversity hot spots, such as the Amazon and tropical Andes, biologist Roberto Cazzolla Gatti of the University of Bologna in Italy and colleagues say.

To estimate the number of Earth’s existing tree species, the team analyzed global forest data from two databases — the Global Forest Biodiversity Initiative and TREECHANGE. The researchers used a statistical analysis to account for the number of rare, infrequent trees that could be overlooked, revealing the new difference between documented species and novel ones.

If more than 9,000 types of stationary, comparatively massive trees remain undetected, Cazzolla Gatti says, then the number of much smaller and more mobile animal species that are still unknown must be even greater.

The research could help scientists target conservation efforts amid accelerating biodiversity loss worldwide (SN: 4/22/20). In vulnerable places such as the Amazon, where deforestation and fires are quickly erasing habitat, many plants and animals could be being wiped off the map before they are ever documented (SN: 9/1/21).

Continuing to invest in conservation and preserving biodiversity is vital, Cazzolla Gatti says. Without it, “we have not many chances to keep our planet alive.”