1 in 6 native tree species in the US may face extinction

One in six tree species native to the contiguous 48 states is at risk of extinction, according to a first-ever assessment.


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  • One in six tree species native to the contiguous 48 states is at risk of extinction, according to first-ever assessment
  • The most common threats to native trees in the U.S. are invasive insects and diseases, climate change and extreme weather, habitat changes and use of biological resources such as logging, the analysis said
  • According to the researchers, The Global Tree Assessment aims to assess the threats posed by all of the world’s approximately 60,000 tree species, but most species native to the continental US have either never been analyzed or the assessments are out of date
  • The researchers concluded that 11-16% of tree species are threatened with extinction

The most common threats to native trees in the U.S. are invasive insects and diseases, climate change and extreme weather, habitat changes and use of biological resources such as logging, the analysis said.

The findings are published in the journal Plants People Planet.

According to the researchers, The Global Tree Assessment aims to assess the threats posed by all of the world’s approximately 60,000 tree species, but most species native to the continental US have either never been analyzed or the assessments are out of date.

To fill the information gap, researchers from Botanic Gardens Conservation International-US, The Morton Arboretum, and NatureServe conducted a five-year study to assess threats to all 881 native tree species in the lower 48 states. Scientists are partnering on the project with the US Botanic Garden and the US Department of Agriculture’s Forest Service.

The researchers concluded that 11-16% of tree species are threatened with extinction. They said the findings could help protect species from extinction.

“Trees form the foundation of many of the world’s terrestrial ecosystems,” Sean T. O’Brien, president and CEO of NatureServe, said in a statement. “Understanding what trees are at risk and why is critical to informing conservation of trees and ecosystems across the country.”

Oaks and hawthorns dominate the tree flora of the United States, with 85 and 94 native species, respectively. They are also the most threatened species, with 29 oaks and 17 hawthorns identified as endangered, according to the paper.

Florida (45) and California (44) have the highest number of threatened tree species, the researchers found. The trees, which either evolved in the contiguous United States or are found only here, are largely concentrated in the southeastern part of the country, Texas and California, they noted.

Among the biggest threats to the trees are the emerald ash borer, an invasive insect whose larvae have decimated the ash population by feeding on the living tissue just under the tree’s bark, and a disease known as “laurel wilt” that attacks three types of evergreen trees .

Although such insects and pathogens are considered the biggest threat to tree species, climate change, including the increasing number of forest fires, is likely to exacerbate the situation, the study said.

Ironically, the researchers note that “conserving and restoring trees and native forests on a national (and global) scale has enormous potential to mitigate climate change, particularly through carbon sequestration.”

Ninety-five percent of native tree species in the U.S. can be found in botanical gardens, arboretums or seed banks, the scientists said. However, 17 species are not conserved outside their natural locations, putting them at risk of one day becoming completely extinct.

Currently, the federal government recognizes only eight tree species in the U.S. as threatened or endangered, which carry varying levels of protection and regulation.

“This assessment improves our understanding of the threats facing America’s native trees and will help focus conservation efforts at public gardens, federal agencies and conservation organizations,” said Susan Pell, acting executive director of the US Botanic Garden. .

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