Our planet has many more species of trees than scientists think – Mother Jones


Rainforest in Brazil.DDurrich/Getty Images

This story was originally published by the Guardian and is reproduced here as part of the Climate office collaboration.

There is a There are an estimated 73,300 tree species on Earth, 9,000 of which have yet to be discovered, according to a global tally of tree species by thousands of researchers who used World War II decoding techniques created at Bletchley Park to assess the number of unknown species.

Researchers working on the ground in 90 countries have collected information on 38 million trees, sometimes walking for days and camping in remote places 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 due to human-induced land use change and the climate crisis.

“It’s a massive effort for the whole world to document our forests,” said Jingjing Liang, lead author of the paper and professor of quantitative forest ecology at Purdue University in Indiana, US. “Counting the number of tree species in the world is like a puzzle with pieces spreading all over the world. We solved it together as a team, each sharing their own piece.

Although they are among the largest and most widespread organisms, there are still thousands of trees yet to be discovered, with 40% of unknown species thought to be found in South America, according to the article published in the journal Proceedings of the National Academy of Sciences. Some of these undocumented species would likely have been known to indigenous communities, but some, in more inaccessible regions, may never have been found before.

The Amazon Basin appears to have the greatest diversity of tree species locally, with 200 tree species per hectare. Researchers believe this could be because it is a warm, humid environment suitable for a greater number of species.

To estimate the number of unknown species, the scientists used the Good-Turing frequency estimate, which was created by decryptor Alan Turing and his assistant Irving Good when they tried to crack German codes from the Enigma machine. during WWII.

The theory, which was developed by Taiwanese statistician Anne Chao for application to the study of undetected species, helped researchers determine the occurrence of rare events – in this case unknown tree species – using data on 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 undetected species.

The idea for an inventory of the planet’s trees came 10 years ago when Liang found data on Alaska’s trees in a drawer. He was impressed with the results and made it his personal mission to get the data online. He then wrote a proposal to make an inventory of the whole world. “People laughed at me first,” he said.

There is no data on how the number of tree species may have changed over time, although many species are considered threatened with extinction due to deforestation and the climate crisis. . Scientists fear that many will disappear before they have been documented.

Liang said, “We hope this paper will provide us with baseline data so that we can know if the total number of tree species in the world has declined, especially during our mass extinction event.

“We must consider the forest not only as a reservoir of carbon, nor as a resource to be extracted; we should think of our forests as a habitat that contains tens of thousands of tree species, and even a much higher number of flora and fauna – we need to pay attention to this biodiversity.

Dr Ruth Mitchell, a plant and soil ecologist at the James Hutton Institute in Scotland, who was not involved in the research, said it showed that even for organisms as large as trees, new species were still being discovered .

“It’s very exciting, but at the same time worrying, we’re losing so much biodiversity so quickly that we don’t even know it,” she said. “This study highlights the incredible diversity of 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 article, said: “The article shows that almost half of the world’s tree species are found in South America – this is undeniable proof that we must not destroy the tropical forests there.

“The diversity of tree species has taken billions of years to accumulate in the Amazon,” he said. “It would be beyond recklessness to destroy it in a century.”


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