(Web Desk) - The world's trees may also be one of its most threatened organisms, according to a new study published Thursday in the journal Science.
It finds that many more tropical tree species are in danger of going extinct far sooner than previously thought.
The results add to the evidence for a growing, global biodiversity crisis as the climate warms and human activity pushes more and more plants and animals to the brink.
"Reversing this crisis is a pressing challenge," write study authors led by Renato A.F. de Lima of the Naturalis Biodiversity Center in the Netherlands, in Science.
The researchers used an automated process to assess millions of herbarium and forest inventory records, specifically looking at the Atlantic Forest — a huge region that spans eastern Brazil as well as parts of Paraguay and Argentina.
The region is home to more than 15,000 plant species, half of which are endemic. About 80% of its original tree cover is already gone, and its borders are home to 35% of all the people in South America.
"A comprehensive assessment at the Atlantic Forest scale could provide insights into the conservation status of other tropical biodiversity hotspots," the authors said.
In total, they assessed almost 5,000 tree species based on criteria from the International Union for Conservation Nature (IUCN), including about 1,100 whose conservation status had never been examined.
A total of 65% were found to be threatened; if only the endemic species were considered, that number rose to 82%.
"The conservation status of the Atlantic Forest tree flora is alarming but probably worse in reality," the authors said.
Extrapolating out to 17 other large tropical forests from the Amazon to Indonesia, they estimate that between 20,000 and 25,000 tropical tree species are likely threatened thanks entirely to habitat loss — that's as many as 43% of all the tree species on the planet, far above previous estimates.
For example, a global assessment by Botanic Gardens Conservation International in 2021 found that about 30% of tree species were at risk.
That group's secretary general Paul Smith said at the time that the report was "a wake up call to everyone around the world that trees need help."
The latest study suggests an even greater biodiversity crisis is ongoing.
"Considering the ecological and sociocultural importance of tree species and the continued pressure on tropical forests," the study authors said, "fighting tropical deforestation... must be prioritized if we are to prevent the extinction of thousands of tree species in the next decades."