By Sellainne Cathry
Ten years ago, Jingjing Liang, Professor of quantitative forest ecology at Purdue University in Indiana, US, became inspired by data on Alaska’s trees that he found sitting in a drawer. So he decided to write a proposal to document the mammoth task of taking an inventory on ‘How many tree species are there on Earth?’
The question led to international cooperation for the unusual project, involving approximately 150 scientists and thousands of researchers working at ground level in 90 different countries.
They all collaborated by pooling their knowledge and data, combining tree collection records from across the planet and engaging in global joint forest missions to ascertain the answers. Various computational techniques were utilised along with studies and research to estimate the “first scientifically credible” global tree species count.
Earth’s global trees finds 73,000 species
The study published in the journal Proceedings of the National Academy of Sciences (PNAS) revealed that Earth is home to 73,000 different tree species and approximately 40 million trees, of which 9,200 are yet to be discovered.
It was found that there are 14 per cent more tree species than previously thought. “It is a massive effort for the whole world to document our forests,” said Liang, “counting the number of tree species worldwide is like a puzzle with pieces spreading all over the world. We solved it together as a team, each sharing our own piece.”
Co-author of the Tree Species Study and Professor of Tropical Ecology in the School of Geography at Leeds University, Oliver Phillips, noted that forty-three per cent of Earth’s total tree diversity grows in South America, with 3,900 tree species in this one continent alone believed to be as yet undiscovered.
The analysis showed that many undiscovered species are rare, restricted to relatively small areas and tropical, and concentrated in endangered diversity hotspots where the Amazon forest meets the Andes in Peru, Colombia, Ecuador, Venezuela and Bolivia.
“This makes forest science and conservation, of paramount priority in South America,” Phillips said, adding, “Knowing how many species there are – and especially where diversity and rare species are concentrated – is essential if we are to protect them, the carbon they store and the myriad other unique plants and creatures sheltered beneath their boughs. With old growth forests still being destroyed across the world over lack of awareness about what is being lost is of great concern. Meanwhile, politicians often talk about “Planting a Trillion Trees” – as if simply covering land with new trees will ever compensate for losing nature’s masterpieces.”
UK Universities’ report on deforestation causing global warming and climate change
There is no information on how the number of tree species may have changed over time. Yet, the challenge is to protect the trees we do have, respect the rarity of endangered species and eliminate their impending extinction due to deforestation, which along with other devastating consequences, is also a significant cause of global warming, creating change in the climate. This human-driven vicious circle then affects the ecosystem creating more unnecessary forest loss.
A report from a collaboration of UK Universities titled “Deforestation will have ‘Drastic Impact’ on South America,” cites Dr Geoff Parkin from Newcastle University stating, “Mean annual temperatures could increase by up to 2.2 degrees celsius in the Northern savannahs and that nearly two-thirds of the Amazon would experience longer and more severe droughts,” adding, “forests in Venezuela and Brazil would also experience an increase in rainfall by up to 25%, severely impacting remote indigenous communities, food supply and ecosystem stability.
The Atlantic forest, the second largest to the Amazon, once covered 43,000 square miles. Now only 10 per cent of that area remains due to deforestation and subsequent use of the land to grow mainly coffee and sugar and rear cattle for the beef industry. The forest once covered parts of Brazil, Argentina, Uruguay and Paraguay. According to data released on 2 February, 140 square miles of forest in the Brazilian Amazon were destroyed by deforestation just in January alone this year.
Trees are not dispensable or replaceable commodities
Professor Liang feels that the Amazon and other forests should not be viewed just as a commodity to take from or as a means to line the coffers of logging companies. “We need to look at the forest not just as a carbon reservoir or a resource for extraction, we should look at our forests as a habitat that contains tens of thousands of species of trees and even a much higher number of flora and fauna; we need to pay attention to this biodiversity,” he said.
Trees also produce oxygen, the fundamental life-giving substance we all need to breathe. A 2019 report by Anne Marie Helmenstine PhD, evaluated that “A mature leafy tree produces as much oxygen in a season as ten people inhale in a year.” She also established that “One acre of trees annually consumes the amount of carbon dioxide equivalent to that produced by driving an average car for 26,000 miles. That same acre of trees also produces enough oxygen for 18 people to breathe for a year.”
And they all need protecting
It is hoped that with the findings of the Tree Species Study, further credence and importance over the protection of forests will be afforded. Martin Lukac, Professor of Ecosystem Science at Reading University, said, “The paper shows that almost half of the world’s tree species are in South America – this is diamond-hard proof that we must not destroy the tropical forests there. The tree species diversity took billions of years to accumulate in the Amazon; it would be beyond reckless to destroy it inside a century.”