Celebrate the conservation benefits of plant collections this Arbor Day
Botanical gardens and arboreta are among my favorite places to visit, including on National Arbor Day this April 24. Not only are their tree and plant collections beautiful to admire, they are fundamental to science and plant conservation.
On Arbor Day, we celebrate trees and their benefits — from cleaning the air we breathe to boosting mental well-being and so much more. It’s also important to recognize the many ways plant collections at botanical gardens and arboreta, or outdoor tree museums, help protect nature for the benefit of us all.
Behind the scenes of these institutions are networks of professional horticulturists, scientists and curators engaged in the important work of caring for plants, understanding what helps them thrive, and protecting them from extinction through plant collections.
Ecosystems rely on biodiversity to function. With nearly half of the world’s flowering plant species potentially threatened with extinction, plant collections are an important tool for protecting biodiversity.
When it comes to trees specifically, one in three species is threatened worldwide, mostly as a result of human activity. That breaks down to 17,500 threatened tree species out of 60,000 — double the combined number of threatened mammals, birds, amphibians and reptiles, according to the 2021 State of the World’s Trees report.
Preventing extinction is the ultimate goal for plant conservation; however, preserving plants in the wild is not always feasible. That is where plant collections come in to help.
Plant collections provide many research insights, such as how individual plant species are responding to climate change, both in the wild and cultivated gardens. They can help us better understand a plant’s requirements to remain resilient in our changing climate, and even support restoration in the wild.
The Morton Arboretum’s 1,700-acre site, which is twice the size of New York City’s Central Park, has more than 100,000 trees and plants in its outdoor museum collection. We grow and study trees to understand how to make natural areas and urban forests more climate resilient. Trees reduce urban heat islands, help manage stormwater runoff, and remove carbon dioxide and pollutants from the air, making them an important part of the solution to addressing climate change.
The Arboretum’s collections also support plant conservation through innovative practices like conservation groves of endangered trees, specifically paperbark maples, maple leaf oaks, Georgia oaks, and Oglethorpe oaks. Conservation groves aim to capture and preserve the genetic diversity of wild populations of endangered species.
Planted by Arboretum staff on Arbor Day in 2023, the paperbark maple conservation grove has 30 thriving young trees. Paperbark maple — prized for its magnificent cinnamon-colored, peeling bark — was originally brought to North America from China by British plant collector E.H. Wilson in 1901. Although it’s a popular landscape plant, there are fewer than 250 individual paperbark maple trees in the wild.
Further, most of the paperbark maples in cultivation in North America are derived from the handful of plants Wilson imported from China in the early 20th Century. This means very little genetic diversity of this species is represented in cultivation.
We are working with North American and Chinese botanical gardens to change that. Together, we have successfully collected seeds and cuttings from wild populations in China to establish paperbark maple conservation groves not only at the Arboretum, but also at our partner institutions.
Plant collections help improve the odds of species survival by preserving genetic diversity. This Arbor Day, let’s celebrate all that botanical gardens and arboreta do to protect plants from threats like climate change and habitat loss, and appreciate them for more than just their beauty.
• Mark Richardson is vice president of collections and horticulture at The Morton Arboretum.