There are about 390 billion individual trees in greater Amazonia, according to estimates based on over 10 years of data. The region has 16,000 tree species but, over half of all trees belong to 227 "hyperdominant" tree species.

Despite being home to the world's largest carbon sink, vast regions of the Amazon have largely remained unexplored. The latest study was conducted by over 100 experts who contributed data from over from 1,100 forestry surveys. Greater Amazonia includes Amazon Basin and the Guiana Shield.

"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! 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," said Hans ter Steege, first author on the study and researcher at the Naturalis Biodiversity Center in South Holland, Netherlands.

Euterpe precatoria, a palm tree native to central and southern America was the most dominant tree in the Amazonia with over five billion trees in the region, BBC reported.

The study team used mathematical models to estimate the number of rare trees in the area. Their analysis showed that there are about 6,000 tree species in Amazon that have fewer than 1,000 specimens. Sadly, many of these may never be studied as they are most likely to go extinct soon.

Researchers have called this phenomenon the "dark biodiversity". Miles Silman of Wake Forest University explains why:

"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. That's a real problem for conservation, because the species at the greatest risk of extinction may disappear before we ever find them," said Silman in a news release.

The study is published in the journal Science.