Researchers have finally counted the number of tree species in the Amazon; they determined there are 16,000 tree species in the region. Half of the total number of Amazon trees belongs to a mere 222 species.
The task of discovering the number of regional trees was so difficult because the Amazon basin and the Guiana Shield combined cover an area equal to about "48 contiguous North American states," a Field Museum news release reported.
"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, Robert O. Bass Visiting Scientist at The Field Museum in Chicago, and co-author on the study, said.
The team studied data from about 1,170 forestry surveys conducted around the Amazon over a 10 year period. The team found there are about 390 billion trees total in the vast, and often treacherous, Amazon.
"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," Hans ter Steege, first author on the study and researcher at the Naturalis Biodiversity Center, said.
These tree species were dubbed "hyperdominants," these species are believed to be responsible for about half of the region's carbon.
The study didn't only look at hyperdominants, the team also researched rare Amazon tree species. A mathematical model used in the study found that about 6,000 local species has populations of less than 1,000. If this is true the trees would be classified as threatened species, the problem is they may never be physically found.
"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," Ecologist Miles Silman of Wake Forest University, another co-author of the paper, said, calling the phenomenon "dark biodiversity.
The team is fairly confident that hyperdominants exist in parts of the Amazon that humans have never been, but they're not sure what causes some trees to grow in such abundance.
"There's a really interesting debate shaping up," Pitman, said. "Between people who think that hyperdominant trees are common because pre-1492 indigenous groups farmed them, and people who think those trees were dominant long before humans ever arrived in the Americas."
