A project previously made highly difficult by rough terrain and sheer volume, scientists from nearly 90 different institutions have concluded that the Amazon Forest is home to about 16,000 different tree species.

According to a news release, researchers, scientists, taxonomists and students from 89 different institutions around the world have combined for the study. Published Thursday in the journal Science, the study's 100-plus contributors have likely helped Amazonian conservation efforts on a basin-wide scale.

"In essence, this means that the largest pool of tropical carbon on Earth has been a black box for ecologists, and conservationists don't know which Amazonian tree species face the most severe threats of extinction," Nigel Pitman, co-author on the study, said.

The study's plethora of contributors has submitted data from 1,170 forestry surveys in all types of major Amazonian forests. According to Hans ter Steege, a researcher at the Naturalis Biodiversity Center in South Holland, Netherlands and lead author of the study, there are at least 16,000 types of tree species in the Amazon and half of the trees in the basin belong to 227 of those species.

"We think there are roughly 16,000 tree species in Amazonia, but the data also suggest that half of all the trees in the region belong to just 227 of those species," he said. "Thus, the most common species of trees in the Amazon now not only have a number, they also have a name. This is very valuable information for further research and policymaking."

Because of the study, researchers now know of several thousand tree species with very small populations. About 6,000 species contained less than 1,000 individuals, qualifying them for International Union for Conservation of Nature (IUCN) Red List of Threatened Species.

Wake Forest University ecologist Miles Silman, a co-author, said this is a problem for the tree species since they are so rare and the forest so vast, that conservationists may never find them.

"Just like physicists' models tell them that dark matter accounts for much of the universe, our models tell us that species too rare to find account for much of the planet's biodiversity," he said. That's a real problem for conservation, because the species at the greatest risk of extinction may disappear before we ever find them."