The number of tree species on Earth is around 73,000, or about 14% more than the species currently known.
Science has come a long way in understanding the natural world, but there are still plenty of unknowns out there. One such unknown is the number of species on Earth, which is currently estimated to be around 8.7 million. Of tree species alone, there might be a lot more out there than previously thought.
A team of more than 100 scientists has reached this conclusion after assembling the largest forest database to date from across the globe.
The researchers estimate the number of tree species to be around 73,000. That is about 14% more than the current number of known tree species on the planet, which means that some 9,200 still unknown species of tree have yet to be discovered by science, the experts postulate.
These undiscovered species are both rare and grow only in small clusters, which makes them particularly vulnerable to deforestation and climate change, they explain in a new study. That is why, they add, preserving existing forests is of primary importance: their loss would have catastophic consequences for the planet’s biodiversity of plants and animals.
To estimate the number of tree species on earth, the researchers combined tree abundance and occurrence data from two global datasets and found that there are 64,100 documented tree species all across the planet.
“We combined individual datasets into one massive global dataset of tree-level data,” explains Jingjing Liang of Purdue University in the United States, who is the coordinator of the Global Forest Biodiversity Initiative and was a lead author of the study.
“Each set comes from someone going out to a forest stand and measuring every single tree: collecting information about the tree species, sizes and other characteristics. Counting the number of tree species worldwide is like a puzzle with pieces spread all over the world,” the scientist adds.
Once they have combined these extensive datasets, the researchers then used advanced statistical methods to estimate how many unique tree species are at various scales (biome, continental and global), including as yet undiscovered species.
Based on the results, they posit that there are at least 73,274 species of tree of Earth, of which some 9,200 have not yet been discovered and described by science.
Around 40% of the undiscovered tree species are presumed to be in South America, which is more than on any other continent, they note. South America has the highest estimated number of rare tree species (about 8,200) of any continent and its hot spots of undiscovered tree species likely “include the tropical and subtropical moist forests of the Amazon basin, as well as Andean forests at elevations between 1,000 meters and 3,500 meters,” the scientists observe in a statement.
“Beyond the 27,000 known tree species in South America, there might be as many as another 4,000 species yet to be discovered there. Most of them could be endemic and located in diversity hot spots of the Amazon basin and the Andes-Amazon interface,” explains Peter Reich, a forest ecologist at the University of Michigan.
“This makes forest conservation of paramount priority in South America, especially considering the current tropical forest crisis from anthropogenic impacts such as deforestation, fires and climate change,” he adds.
Across the planet anywhere between half and two-thirds of all already known tree species occur in tropical and subtropical rainforests, which tend to be species-rich but poorly studied, and so large numbers of undiscovered tree species might be hiding in plain sight within them.
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