There are an estimated 73,300 tree species on Earth, 9,000 of which have yet to be discovered, according to a global tree species count by thousands of researchers using WWII code-breaking techniques created at Bletchley. unknown species. .
Researchers working in the field in 90 countries collected information on 38 million trees, sometimes walking for days and camping in remote locations to reach them. The study found that there are about 14% more tree species than previously reported and that a third of undiscovered tree species are rare, meaning they could be vulnerable to extinction from changes in climate, land use by man and the climate crisis.
“It’s a big effort for everyone to document our forests,” said Jingjing Liang, the paper’s lead author and professor of quantitative forest ecology at Purdue University in Indiana, USA. “Counting the number of tree species around the world is like a jigsaw puzzle with pieces scattered around the world. We work together as a team, each sharing its own piece.”
Despite being among the largest and most widespread organisms, thousands of trees have yet to be discovered, with 40% of the unknown species found in South America, according to the article published in the journal Proceedings of the National Academy of Sciences (PNAS). ). Some of these undocumented species would likely be known to indigenous communities, but some, in the most inaccessible regions, may never have been found before.
The Amazon contains the largest number of tree species in the world
THE Amazon basin appears to have the highest diversity of tree species locally, with 200 tree species per hectare. The researchers believe this may be because it is a warm and humid environment suitable for supporting a wide range of species.
To estimate the number of unknown species, the scientists used the Good-Turing frequency estimate, which was created by codebreaker Alan Turing and his assistant Irving Good when they were trying to decipher German codes for the Enigma machine during World War II.
The theory, developed by Taiwanese statistician Anne Chao to be applied to the study of undetected species, helped researchers determine the occurrence of rare events, in this case unknown tree species, using data from observed rare species. Essentially, the code uses information about species that are only detected once or twice in the data to estimate the number of species lost.
The idea of making an inventory of the planet’s trees came about 10 years ago, when Liang found data about Alaska’s trees in a drawer. He was impressed by the findings and made it his personal mission to get the data online. So he wrote a proposal to take an inventory of the entire world. “People initially laughed at me,” he said.
Many species are considered endangered
There is no data on how the number of tree species may have changed over time, although many species are in danger of extinction due to deforestation and the climate crisis. Scientists are concerned that many will disappear before they are documented.
Liang said: “We hope this paper will provide us with baseline data so that we can know whether the total number of tree species in the world has declined, especially during our mass extinction event.
“We need to see the forest not just as a carbon reservoir or a resource for extraction; we must consider our forests as a habitat that contains tens of thousands of species of trees and even a much larger number of flora and fauna; We must be aware of this biodiversity.”
Ruth Mitchell, a plant and soil ecologist at the James Hutton Institute in Scotland who was not involved in the research, said it shows that even for organisms as large as trees, new species are still being discovered.
“It’s very exciting, but at the same time worrying that we’re losing so much biodiversity so quickly that we don’t even realize it,” he said. “This study highlights the incredible diversity within our forests, much of which is still waiting for us to discover.”
Martin Lukac, professor of ecosystem science at the University of Reading, who was also not involved in the paper, said: “The paper shows that nearly half of the world’s tree species are found in South America; this is strong proof that we shouldn’t destroy the rainforests there.
“The diversity of tree species took billions of years to accumulate in the Amazon,” he said. “It would be more than unwise to destroy it in a century.”
By Phoebe Westton. Article in English