By Andy Schmitz, Director of Horticulture and General manager

This article was originally published in The Brenton Arboretum’s Spring 2018 newsletter.

Did you know that out of more than 60,000 different species of trees in the world, 10,000 of these are under threat of extinction from insects, diseases, habitat destruction and/or climate change? The International Union of Conservation of Nature (IUCN) Red List is a comprehensive inventory of the global conservation status of biological species including trees of the world. The IUCN evaluates species extinction risks and works to reduce extinction.

In January, the Red List of Fraxinus (ash trees) was completed. Our native ash species is “critically
endangered,” facing an extremely high risk of extinction in the wild. The culprit is the introduced pest emerald ash borer, which is decimating white ash, Fraxinus americana, green ash, Fraxinus pennsylvanica, black ash, Fraxinus nigra, and blue ash, Fraxinus quadrangulata. Arboretums and botanical gardens all over the world are working diligently to prevent plant extinctions by conducting research, going on plant collecting expeditions and by simply growing threatened plants in their collections.

The Brenton Arboretum has living accessions of 12 tree species listed on the 1997 IUCN Red List including nine conifer species, two elm species, and ginkgo. With four ash species now listed as critically endangered, we have 16 species preserved in ex situ conservation: outside the natural geographical range of the species. In situ conservation happens in the species’ native habitats.

One Red List tree we have is the Fraser fir, Abies fraseri, which is native to parts of the Appalachian Mountains of North Carolina, Tennessee, and Virginia. It is listed as “endangered” from the threat of
another introduced pest, the balsam woolly adelgid. It feeds on Fraser fir trees, eventually killing them. Three Fraser firs growing on the west side of the Arboretum are helping to preserve the species ex situ.

In our effort to be an institution dedicated to doing our part to preserve tree species, we can use the Red Lists to identify species under threat and then attempt to grow them. Over the winter, I was looking at the Red List of Quercus (oak trees) and learned about maple-leaved oak, Quercus acerifolia, native to only four counties in the Ouachita Mountains in east-central Arkansas. With this limited range and fewer than 600 trees known to exist in the wild, it has been listed as “endangered,” which means it is facing a very high risk of extinction in the wild.

Knowing this, individuals from the Morton Arboretum and Dawes Arboretum collected acorns from the native populations in Arkansas this past September. These acorns were distributed to several institutions around the country to use in their ex situ conservation efforts. We are hoping to acquire some seedlings this spring to add maple-leaved oak to The Brenton Arboretum oak collection.

Trees all over the world are being threatened for various reasons. I encourage you to learn more about tree conservation by visiting the Botanical Gardens Conservation International website, BGCI.com, and Global Trees, globaltrees.org, to learn more about threatened trees. I also invite you to come out to visit the trees at the Arboretum to see if there are any you would like to plant in your yard to start your own ex situ conservation project.