Amazon Forestry Survey Finds Roughly 16,000 Tree Species
October 18, 2013

Hyperdominant Trees Make Up Half Of Amazon Forests

redOrbit Staff & Wire Reports - Your Universe Online

Researchers have discovered that there are nearly 400 million individual trees in the Amazon, and while there are over 16,000 different types, approximately half of them belong to just 227 unique species.

Those startling findings are the result of a study, published Thursday in the journal Science, in which more than 100 scientists, taxonomists and students from 89 global institutions set out to determine the total number of trees and tree species living in the South American region.

The experts contributed data from 1,170 forestry surveys in all major forest types in the Amazon. Their efforts have helped create the first basin-wide estimate of the abundance, the frequency, and the spatial distribution of the thousands of trees living in the area, which includes regions of Brazil, Columbia and Peru.

The size of the Amazon Basin, along with the Guiana Shield (Guyana, Suriname, and French Guiana), has made it difficult to study the diversity of the trees living there. The region spans an area approximately as large as the 48 contiguous US states, the researchers said, and the lack of knowledge about the flora located there has hindered both scientific and conservation efforts.

“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,” stated study co-author Nigel Pitman, Robert O. Bass Visiting Scientist at The Field Museum in Chicago.

Pitman and his colleagues collected data over the greater Amazonia region (which includes both the Amazon Basin and the Guiana Shield) over a period of 10 years. They found that the various forest types in that region are home to roughly 390 billion individual trees, including Brazil nut, chocolate, and açai berry trees.

“We think there are roughly 16,000 tree species in Amazonia,” said Hans ter Steege, first author on the paper and a researcher at the Naturalis Biodiversity Center in the Netherlands, “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.”

The investigators have dubbed those 227 species “hyperdominants,” and explained that even though they make up less than two percent of the tree species located in the Amazon region, they account for nearly half of its carbon and ecosystem services. Furthermore, they found that none of those hyperdominant species are common throughout the Amazon; rather, most dominate one region or forest type.

“The study also offers insights into the rarest tree species in the Amazon,” the Field Museum said. “According to the mathematical model used in the study, roughly 6,000 tree species in the Amazon have populations of fewer than 1,000 individuals, which automatically qualifies them for inclusion in the International Union for Conservation of Nature (IUCN) Red List of Threatened Species.”

Unfortunately, those species are so rare that it will be difficult – if not impossible – for researchers to find them. It is a phenomenon that co-author and Wake Forest University ecologist Miles Silman calls “dark biodiversity.”

Silman compared it to physicists’ ongoing search for dark matter, and said, “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.”