September 23, 2017 – A Couple of PhDs Talking Tree Extinction

You know it’s not going to be a good day when you receive an email that features this headline:


Okay, I think I’ll add a little Bailey’s Irish Cream to that morning cup of coffee.

Anyway, there’s a group that’s known as the International Union for Conservation of Nature (IUCN), and it has created something called the Red List of Threatened Species™. I’m a little foggy on why they would find it necessary to trademark the list, but they call it “the world’s most comprehensive inventory of the global conservation status of plant and animal species.” The IUCN Red List now includes 87,967 species of which 25,062 are threatened with extinction.

Now researchers at The Morton Arboretum, in collaboration with the IUCN Global Tree Specialist Group and the University of Notre Dame, have concluded that five of six of the most prominent ash species are Critically Endangered:

  • White ash (Fraxinus americana)
  • Carolina ash (Fraxinus caroliniana)
  • Black ash (Fraxinus nigra)
  • Green ash (Fraxinus pennsylvanica)
  • Pumpkin ash (Fraxinus profunda)
  • Blue ash (Fraxinus quadrangulata)

You might recognize some of those yourself, as white ash, green ash and black ash are among the most common ash trees in the United States. What does it all mean? Dr. Murphy Westwood, who is director of Global tree conservation at the Morton Arboretum, states,

Ash trees have been essential to plant communities of the United States and have been a vastly popular horticultural species, planted by the millions along our streets and in gardens. The likelihood that we are losing more than 80 percent of these trees has, and will continue to, dramatically change the composition of both wild and urban forests. Now, our challenge is to figure out what will fill those gaps and how the community dynamics of those forests will change.

By the way, unless you’ve been living on the Cassini spacecraft, and you’ve now plunged into the planet Saturn’s atmosphere, you know that the cause of all of this is an insect called emerald ash borer (Agrilus planipennis), or EAB, which made its way to Michigan at the end of the 20th century in infested shipping pallets. To date, it has been discovered in 31 states and two Canadian provinces, and has killed hundreds of millions of trees.

While ash trees can be treated with various pesticides, and even biological controls are being tested, in the long run those are unlikely to save the various species from extirpation.

And if that weren’t bad enough, how about this headline:

New study finds 16 of the nation’s oak species are in danger of extinction

Pass the Bailey’s.

Once again, the Morton Arboretum’s Global tree conservation is involved. Their scientists gathered data on the locations, populations, and threats facing all 91 native U.S. oak species and classified 16, all in the South or Southwest, as critically endangered, endangered, or vulnerable, for the IUCN Red List of Threatened Species (those guys again). By 2020, the Arboretum has pledged to assess all 450 of the world’s oak species.

Dr. Murphy Westwood joins us in studio this morning to discuss these disturbing reports. She is joined by an old friend of mine, Dr. Rex Bastian, technical advisor for Davey Tree Expert Company. I’ve known him for about fifteen years, since the local arm of Davey was known as The Care of Trees.

The other week, I saw that Dr. Bastian had been the recipient of this year’s International Society of Arboriculture’s (ISA) Award of Merit. ISA’s most prestigious Award of Distinction, the Award of Merit, acknowledges Bastian’s service in advancing the principles, ideas, and practices of arboriculture.”

Well, you’re not going to find two more qualified people to talk about trees on one radio show anytime soon, so I suggest you tune in…or at least catch the podcast.