Ode to the beech tree

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In school we all learned how crucial trees are to our environment (crib note — they keep us alive), but aside from their ecological benefits, trees are beloved for numerous other reasons. Kids love to climb them, artists long to paint them, arborists meticulously care for them, and many indigenous tribes, including the Wampanoag Tribe of Gay Head (Aquinnah), have been honoring and tending trees for thousands of years. 

Acknowledging that humans tend to anthropomorphize nearly everything — animals, plants, robots, their cars — to better understand their experiences, I still can’t help but wonder if our connection to trees is because we have more in common with them than we may realize.

We stand upright, have a crown and limbs that stem out from a core trunk, and the bronchi in our lungs resemble the root system of many trees. Like humans, trees straddle the realm between life and death — some maintaining their leaves while other sections begin to decline. Most trees reach maturity long before their biological lives are complete, and like many people, before they reveal their most amazing characteristics. 

Many species of trees have what we might consider a communal spirit. They are engaged listeners and generous communicators, “chatting” through networks created by mycorrhizal fungi connecting their roots. Through these networks, trees not only communicate issues that arise, but they also support their neighbors by sharing resources — transporting carbon, water, and nitrogen to assist younger or weaker trees, including those of different species. 

In a Smithsonian article, “Do trees talk to each other?” author Richard Grant shares his experience of taking a guided walk with German forester and author of “The Hidden Life of Trees,” Peter Wohlleben: “Wohlleben takes me to two massive beech trees growing next to each other. He points up at their skeletal winter crowns, which appear careful not to encroach into each other’s space. ‘These two are old friends,’ he says. ‘They are very considerate in sharing the sunlight, and their root systems are closely connected. In cases like this, when one dies, the other usually dies soon afterward, because they are dependent on each other.’” 

Unfortunately, beech trees may not be able to depend on one another for long, as high numbers of native and ornamental beeches are dying from beech leaf disease (BLD). 

“Beech leaf disease is caused by a microscopic worm called a nematode,” Polly Hill Arboretum (PHA) certified arborist and grounds manager Ian Jochems says. “This nematode lives and develops between the cuticle layers of the leaves, causing damage, which reduces photosynthesis and, in turn, weakens or kills the trees.”

Affected beech trees can be identified by their leaves, which exhibit dark interveinal banding, or in some cases are curled or distorted. Since its discovery, BLD has been detected in Ohio, Connecticut, Delaware, Maine, Massachusetts, Michigan, New Hampshire, New York, New Jersey, Pennsylvania, Rhode Island, Virginia, West Virginia, and the Canadian province of Ontario. 

So why are beech trees so heavily targeted by pathogens and pests? “They fit the classic invasive species model, whereby an organism (or organism complex) is taken out of its native habitat and introduced (typically by humans) to a new environment,” says Dr. Matthew Borden, research scientist and plant pathologist of Bartlett Tree Experts. “The organism then becomes widespread and harmful due to an imbalance in the system, such as a lack of natural enemies, a more preferable environment, new ecological associates, more susceptible reproductive hosts, etc.” 

As a plant pathologist, Borden says that although he and his colleagues have joked that they like plants that are dying because that’s what they study, the loss of the beech is different. “This is very different from seeing a boxwood die from over-irrigation. It hits home for me. Seeing the radical change from a beautiful dense canopy to extremely thin canopy in just a couple years is hard. There has been an emotional response, even for a pathologist.” 

Polly Hill’s curator and assistant director, Emily Ellingson, and I took a walk to look at various species of beeches onsite. “We have American beeches — there are a few in our living collections (the 25 acres of cultivated plants) — and there are many in the 40 acres of woodlands. We also have 11 total different types of beeches in our living collection.”

Ellingson showed me a few beeches infected with BLD, and explained that the disease is most likely spread in a variety of ways. “In the summer through fall, the nematodes will actually crawl out of the leaves and into the newly formed buds that hold the next year’s leaves. Wind-driven rain can splash them on the ground, where they can be picked up and moved by a variety of insects and mammals. They may spread farther distances via birds, or possibly even nurseries.” 

The impacts of BLD are about more than just the loss of a beautiful tree. “On-Island, you will often find beeches growing clonally, in large patches,” Ellingson continues. “Losing trees will create canopy gaps which could be filled in by introduced plants that can cause ecological damage. Beeches are also important to wildlife — their nuts provide food. Anytime you lose something from an ecosystem, there are ecological consequences that can be somewhat unpredictable.”

Though disheartening, there may be hope for beeches. “Invasive species can surprise us,” Borden says. “There is an aspect of ‘we do not know what we do not know’ when it comes to their movement and interaction with the affected host. It is possible that we will be surprised by a resistant population, or a natural enemy that emerges, or a population collapse of the nematode once enough beech trees have died.”

Jochems states that there are currently two treatment options that they are recommending and seeing good results with. “One treatment is a foliar spray, performed four times a year. The second is a basal trunk injection, which is a trunk injection method that delivers pesticides, insecticides, or nutrients directly into the trunk of a tree by drilling small holes at the tree and inserting specialized ports or capsules.” 

When asked what Islanders should know, Jochems says that the community needs to recognize the impact of invasive weeds, and have a plan to manage them, paired with replanting efforts. “They go in tandem. Planting other native trees, perhaps, or planting more oak and hickory for animals.”

Borden points out that we need to be realistic in our expectations while also being proactive. “It is quite possible that a majority of beech in natural areas will die from one or both of these major diseases. Still, none of that means we can’t or shouldn’t try to help. In my opinion, invasive plant species ingress will be the most serious short-term effect of beech leaf disease, and this is something we can help address.” 

How to start? “If you own woodlands, we don’t recommend removing living or dead beech trees unless they cause a safety concern,” Ellingson says. “Some living, mature trees may yet survive, and standing dead can provide habitat for wildlife. Polly Hill provides an update every year in the form of a talk or an article in our newsletter. We will continue to provide new information as we learn it.”

Jochems recommends hiring a certified arborist who is a licensed applicator. “We want people to know that we understand how emotional and devastating this can be. Still, Mother Nature is resilient, and if we work with her, we can turn a loss into a positive step forward for the next generation. It’s always a great time to plant a new tree.” 

Visit Polly Hill Arboretum at pollyhillarboretum.org, and check out BiodiversityWorks’ program, Natural Neighbors. A representative will come to your home or business and provide information about what native plants and trees are present, and what can be added to help with the Island’s biodiversity.