Managing Beech for Resiliency to Pests and Pathogens at the Wildlands

April 17, 2024

Written by Paulina Murray, Holt Research Forest Fellow. Photos by Logan Johnson, Maine TREE Foundation unless otherwise noted.

Trailhead at Great Pond Mountain Wildlands, Recipient of the 2023 Maine Outstanding Tree Farmer Award. Photo by Logan Johnson, Maine TREE Foundation.

Third in the Maine Forest Climate Change Webinar & Field Tour Series, Maine’s Forest Climate Change Initiative (FCCI) hosted an interactive webinar and field tour at the Great Pond Mountain Conservation Trust’s (GPMCT) Wildlands, which focused on forest pests and pathogens. Recipient of the 2023 Maine Outstanding Tree Farmer Award, the GPMCT Wildlands is described as “a place where you may see a moose while mountain biking, an osprey while paddling along a pristine shore, or enjoy an amazing view from more than one mountain – all within minutes of Rte. 1,” and is the place to go to witness adaptation and implementation in action. Together with the Forest Stewards Guild, Maine TREE Foundation, and UMaine’s Center for Research on Sustainable Forests, the FCCI hosted a diverse group of forest professionals, including foresters, loggers, students, researchers, and family forest owners, to discuss the management of a prominent tree species, forest defoliators, and disease threats in the Acadia region. The session began at stand 241, aptly described by Roger Greene, a forestry consultant with the GPMCT, as “the worst stand of beech I’d ever seen.”

Roger Greene introduces participants to stand 241.

Historically recognized by its smooth, gray bark, the American beech is a native species common throughout eastern North America. With the ability to produce root sprouts, or “suckers,” American beech trees often produce nearly uniform stands, presenting significant challenges in their management. These aggressive growth patterns are exacerbated by disease and mortality, leading to the exclusion of the regeneration of desired species and reduced site biodiversity.

Stand 241 and neighboring stands were originally slated for residential development, but the plans were abandoned before construction in the late 1990s. Acres of land were clearcut and left to regenerate without interference. What resulted were stands of pure beech. Now, there are standing trees, slash, and sprouted stumps in the managed stand, unlike the dense and uniform unmanaged stands. Roger explained how a high-stumping technique, where beech is cut below the first live branch to discourage sprouting, is used in stand 241 to reduce beech regeneration. To some, the managed stand might look messier and unmanaged due to the high piles of slash and stumps left behind. However, this complexity creates more opportunities for wildlife habitats and resources.

Beech regeneration following the high-stumping technique.

Beech trees provide habitat and resources for many wildlife species, including birds, mammals, insects, and more. For example, beech trees commonly provide cover for black-capped chickadees and other cavity-dwellers. Beech masts are particularly important for mice, squirrels, black bears, foxes, ruffed grouse, and ducks. Furthermore, American beech trees support 126 caterpillar species in Maine and, thus, provide more food options for terrestrial birds. At stand 241, Private Lands Biologist Joe Roy with the Maine Department of Inland Fisheries and Wildlife shared a story about weasels using beech slash piles for hunting. By standing on their hind legs at the top of a slash pile, weasels can double their height to give them a better view of their prey, another excellent example of how complexity can provide more opportunities for wildlife.

Beech bark disease is the primary cause of mortality in American beech trees throughout most of their natural range in North America. The disease was first reported on a shipment of infected European beech trees from Europe in 1920 and has since spread steadily throughout most of its North American range. The infection takes part in a two-step process. First, infestation occurs by the beech bark scale Cryptococcus fagisuga, predisposing them to infection by two fungi: Neonectria coccinea var. Faginta and less often N. galligena. The bark scale creates open bark wounds that allow the fungi to infect the tree, resulting in beech trees laden with thick, bubbling cankers and a light red rash blooming across the bark. As the cankers spread, branch and crown dieback eventually result in the tree’s death.

: Contrasts between managed (right) and unmanaged (left) beech stands—photos by Logan Johnson and Paulina Murray, Maine TREE.

One emphasis of the webinar and field tour was embracing the idea of a gradient of resistance to beech bark disease, with some being more susceptible than others. A susceptible beech has sunken cankers and callus tissue with cracked or recessed centers caused by the scale insect infestation and fungal infection. In the middle of the spectrum are tolerant beeches. These trees have delimited cankers and have been infected by the bark scale and fungi but formed a wound periderm, also known as the outer layer of a plant stem thickened in response to infection or wound, preventing the infection from reaching the vascular cambium. Underneath these cankers is clear and healthy bark. A resistant beech looks smooth and free of cankers, wounds, or fungal infections. Resistant beech trees are often found close to one another, and some research indicates that resistance is a genetically inheritable trait that can originate from root sprouts. Their success in resisting the disease may be due to having significantly lower concentrations of some amino acids and amino nitrogen in the bark.

A managed beech stand containing standing trees, slash, and stumps

A lesser-known disease gaining attention is beech leaf disease, which kills native and ornamental beech tree species. The disease was first detected in Ohio in 2012 and later in Waldo County, Maine in 2021. It has since spread prevalently throughout the midcoast region. As the name suggests, beech leaf disease affects the leaves of a beech tree and is associated with the nematode Litylenchus crenatae mcannii. Infected beech tree leaves will have uncharacteristic colors and deformities like dark banding between the veins or shriveled and leathery textures. Premature bud drop, aborted buds, and thinning canopies are other common signs of the disease. However, identifying beech leaf disease can often be challenging because infected trees can simultaneously contain heavily infected clusters of leaves and unaffected branches.

A memorable moment of the tour was when one participant remarked, “It’s all about balance; even doing nothing benefits some, but not others.” As we delve deeper into understanding the dynamics of Maine’s forests and their interactions with pests and pathogens, the concept of balance becomes increasingly important, both in the present and as we plan for the future.

FCCI participants gather for the GPMCT Wildlands field tour.

FCCI is a collaborative effort between Maine TREE Foundation, the Forest Stewards Guild, and UMaine’s Center for Research on Sustainable Forests (CRSF). Through quarterly webinars and field tours, the initiative fosters conversation and learning on the impacts of climate change in the Maine woods.
Join us for the final session of Season 4: Women’s Approach to Climate Adaptation on May 8 (webinar) and 10 (Field Tour). All are welcome! Learn more and register here: https://crsf.umaine.edu/fcci-webinars/