Stressed by encroaching development, deforestation, and climate change, more than a third of the Earth’s tree species are at risk of extinction and upending the ecosystems that depend on them.
For the first time, a majority of the world’s tree species were assessed by a global team of more than a thousand specialists working with the International Union for Conservation of Nature Red List of Threatened Species. The research, presented this week at the U.N. Biodiversity Conference, or COP16 in Cali, Colombia, reveals that tens of thousands of tree species could disappear forever.
The assessment included more than 80% of known tree species and found that 38% of them are at risk.
A 'barometer of life'
“Trees are essential to support life on Earth through their vital role in ecosystems, and millions of people depend upon them for their lives and livelihoods,” says Grethel Aguilar, IUCN's director general. “As the IUCN Red List celebrates 60 years of impact, this assessment highlights its importance as a barometer of life, but also, crucially, as a unique tool guiding action to reverse the decline of nature.”
At least 16,425 of the 47,282 tree species assessed are at risk of extinction. Trees now account for more than a quarter of species on the Red List, with the number of threatened trees more than double the number of all threatened birds, mammals, reptiles and amphibians combined. Tree species are at risk of extinction in 192 countries around the world, with island ecosystems – where tree populations are often small and a species may not exist anywhere else – especially vulnerable.
These isolated ecosystems require urgent, focused protection through habitat restoration as well as off-site conservation efforts, like seed banks and botanical garden collections, conservationists say. Reforestation projects and community-based initiatives have demonstrated success in Cuba, Fiji, Madagascar and Chile’s Juan Fernández Islands.
The impact of climate change
Globally, tree loss is the result mainly of urban and agricultural expansion, invasive species, pests, diseases and deforestation. Scientists are also seeing the impacts of climate change, such as sea-level rise, wildfires and stronger and more frequent storms, playing a role.
The loss of trees also poses an overwhelming threat to thousands of other plants, fungi and animals. Trees, a defining component of many ecosystems, are fundamental to life on Earth through their role in carbon, water and nutrient cycles, soil formation and climate regulation. People also depend on trees; more than 5,000 of the tree species on the Red List are used for timber in construction, and over 2,000 species for medicines, food and fuels.
South America, home to the the Earth’s greatest diversity of trees, was a key research point. Areas across the continent face relentless deforestation driven by agriculture and cattle ranching with 3,356 of the 13,668 assessed species at risk of extinction. Innovative approaches are needed, IUCN says. Colombia, for example, is using Red List data to designate Key Biodiversity Areas to protect endangered tree species including an endangered magnolia.
Risk is likely underestimated
“Although the proportion of tree species reported as threatened in South America … is lower (25%), this percentage is sure to increase, because many tree species from South America have yet to be described for science and tree species new to science are more likely than not to be threatened with extinction,” says Eimear Nic Lughadha, a researcher at London’s Royal Botanic Gardens.
Also added to the Red List was the Western European hedgehog. IUCN says numbers of the small, mostly nocturnal mammal are believed to have shrunk in more than half the countries where it lives, including the U.K., Norway, Sweden, Denmark, Belgium, the Netherlands, Germany and Austria.
IUCN, one of the world’s most respected environmental organizations, launched the Red List of Threatened Species, the world’s most comprehensive information source on the conservation status of plant, animal, and fungi species, in 1964. It is often referred to as the Earth’s “barometer of life.”
