Ecology

The rebellious beauty of American Beech

Anne Gageby
Strawberry Hill Nature Preserve

(9/2023) There’s a wild, rebellious beauty to the American beech tree. It does what it wants, grows in soil too poor for many trees, and quite literally stands out amongst the crowd. It’s simply a cool tree.

American beech, Fagus grandifolia, is also known as ‘elephant bark tree’ or ‘elephant skin tree’ for the way its bark grows a particular shade of gray with a grainy-like texture unique amongst a forest of deeply grooved oaks and plated pines. Take a walk through Strawberry Hill’s campus and you’ll easily spot these magnificent trees every couple of feet. They stand out for their interesting color and bark but also for their rebellious, rule-breaking nature. Beech is a deciduous tree, meaning its leaves are supposed to change color in autumn and fall like the rest of its deciduous brethren. Instead, beech leaves fade to gold then turn brown as they die but continue clinging to branches through winter. It’s an interesting twist on the rules.

Scientists call the process of holding onto dead plant matter marcescence and it’s more common in young trees. Of course, beeches don’t care about the rules so you’ll find beeches of all ages retaining leaves. But why do beech trees hold onto their leaves? There are a couple of theories. One theory suggests that beech marcescence is an adaptation to growing in poor, dry soil. Holding onto leaves until spring slows the decomposition of said leaves and allows the beech to deliver nutrients to itself right when it needs it most. Another theory states the shade produced by a beech canopy allows snow to linger longer than if it were in direct sunlight, thereby allowing the tree to control the moisture content of the soil. Another suggests that old dead leaves create a protective barrier for fresh buds in spring. Dead leaves are ignored while fresh buds make tasty treats for passing deer.

The American beech is a foundational tree species native to eastern North American forests. Its range stretches from southern Ontario and Nova Scotia to eastern Texas and northern Florida. This vital hardwood plays an important role in forest ecology, supporting nesting sites and providing an essential food source for a variety of vertebrates from black bears to squirrels and birds. Beech leaves create a dense canopy which moderates the amount of light reaching the forest floor. As the leaves fall, they create a thick carpet of leaf litter, contributing to nutrient cycling and providing shelter for understory insects and fauna.

A slow-growing tree, beech can reach heights between 60–80 feet with a canopy spread of up to 40 feet. Unlike rough bark trees such as black walnut or spruce, beech’s heartwood grows at the same rate as its periderm, or outer bark. This equal rate produces an outer bark that’s thin, smooth, and relatively soft. This smooth bark protects the tree from insects and climbing plants like ivy and Virginia creeper. Unfortunately, it also makes an attractive canvas for anyone determined to leave their mark. Beech has solidified its place in American culture as a popular tree for carving initials, hearts, dates, and so on. It’s not uncommon to find carvings decades old. After all, a healthy beech can live to be 400 years old.

Whether you appreciate American beech trees for their important role in forest ecology or simply because they’re beautiful trees, it’s important to note that beech trees are facing a major challenge: beech leaf disease. This disease is new and could drastically change forests here on the East Coast, especially in areas where another threat – beech bark disease – hasn’t yet been found. In a doubly sad twist, beech leaf disease will compound the crisis for areas already hit with beech bark disease. Tree dieback and mortality could likely skyrocket.

Beech leaf disease was first discovered in 2012 in Lake County, Ohio, and is characterized by dark interveinal banding of leaves. To get the best view of this banding, stand under a beech and look up. Sunlight filtering through the leaves highlights these dark bands. Leaves affected look green but dry and have the appearance of wrinkled paper. Damaged leaves fall and the stricken tree is forced to grow new ones. The cost to regrow leaves is high. More energy is spent on this process than the tree is able to produce and eventually the tree’s fate is sealed. Small trees die within 3-5 years. It’s currently unknown how beech leaf disease will affect mature beech trees, but it’s been reported that larger trees are dying within six or seven years.

American beech isn’t the only species affected. Non-native European and oriental beech (F. sylvatica, and F. orientalis) are also susceptible to this new threat. It’s also unclear what role climate change could be playing in the spread of this scourge. So, what can be done? There is currently no known treatment or cure, putting large swaths of trees or even entire forests in jeopardy. Monitoring plots have been set up around the East Coast over the last couple of years with funding from the USDA Forest Service. Here in Pennsylvania, researchers with Penn State’s College of Agricultural Sciences are collaborating with U.S. Forest Service to tackle the problem and studies are being conducted as I type.

As of this writing we know that beech leaf disease is spread via nematodes but what role they play exactly is uncertain. For now, we’ll just have to be patient. As for me, I’ll monitor our trees at Strawberry Hill and hope for the best. I use beech as a teaching tool when going out on guided hikes. American beech trees make excellent examples when teaching identification skills as they’re easily identified and visually striking no matter the season. Not to mention their foundational nature makes them critical to a healthy forest and can tell us a lot about the local ecosystem. Plus, there’s just something decidedly cool about them. They’re kingly in their own way and don’t bother with rules. Sometimes the forest likes to show a little sass. And after all, who doesn’t love a rebel?

Anne Gageby is the Environmental Education Manager of the Strawberry Hill Foundation. Strawberry Hill inspires stewardship of our natural world by
connecting the community with educational opportunities.
 Learn more by visiting StrawberryHill.org.