• Indianhead Point stands tall along the Pictured Rocks. Photo copyright Craig Blacklock

    Pictured Rocks

    National Lakeshore Michigan

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Beech Bark Disease

White spots on the bark of beech trees is a clear indication of Beech Bark Disease

An infected beech tree

U.S. Forest Service photo

The American beech, a dominant species in the upland forests of Pictured Rocks National Lakeshore, is seriously threatened by Beech Bark Disease. Beech Bark Disease (BBD) originated in Europe and was accidentally introduced to Nova Scotia around 1890, most likely in an infected European beech tree brought for a horticulture exhibit. It has been spreading slowly through the eastern U.S. ever since.

It was first detected in Michigan in 1990, and discovered at Pictured Rocks in 2001. Advanced by wind, BBD has moved from east to west through the national lakeshore. Biologists estimate that 80 to 90 percent of the park's mature beech trees will not survive.

Beech Bark Disease is the result of a complex interaction between three non-native pests (a tiny scale insect and two species of Nectria fungus) and a native Nectria fungus. The beech scale insect wounds the tree by piercing the bark with sharp mouth parts and sucking out the sap. Nectria fungus is then able to enter and infect the tree through these wounds. Once infected, most beech trees weaken and die slowly over the span of several years. Older larger trees are more susceptible to BBD than younger ones.

Infected trees can be recognized by waxy-white patches of bark, dark cankers, or obvious fuzzy "cotton ball" bumps. Other signs include loss of leaves, broken branches, and discolored foliage. Healthy beech trees have smooth grey bark and dark green shiny leaves.

The loss of beech trees to BBD will affect many animal that depend on nutritious beechnuts for food


Ohio Dept. of Natural Resources photo

Impacts to the Forest Ecosystem
The majestic beech is one of the dominant trees of northern hardwood forests along with maple and hemlock. It is the major nut-producing tree in this ecosystem, and its loss will affect wildlife such as black bear, squirrels, chipmunks, porcupines, white-tailed deer, and birds that depend on this food source. Beech trees are also a favorite nesting site for chickadees, and they provide shelter for woodpeckers, fishers, martens, and other cavity dwellers.

As infected beech fall and die, they create a gap in the forest canopy. Thickets of young beech (sprouting from roots) and saplings of other species will quickly take advantage of the increased space and light to fill in these forest openings.

The change from a closed-canopy forest to a more open one will affect animal populations as well. Increased understory vegetation and woody debris from downed beech trees will favor certain species over others. Hawks and other birds that prefer a dense canopy may no longer nest here. The loss of beech in this forest will have far-reaching impacts that scientists are only beginning to understand.

Park biologist inspecting resistant beech tree at Pictured Rocks National Lakeshore.  The dark and light patches on this tree are non-harmful moss and lichen growths.

Biologist inspecting resistant beech tree

NPS photo / Mike Peters

What can be done?
The sheer number of beech trees throughout the park (40 to 60 percent of some forest stands) makes treating BBD both uneconomical and unrealistic. No large-scale pesticide application or biological control methods currently exist.

However, park staff search for and identify trees that may be immune to the scale insect or fungi that cause BBD. Trees that show no disease symptoms are marked, measured and closely monitored. Resistant trees found here at Pictured Rocks may play a significant role in future efforts to restore beech as a functional component of the forest landscape.


Safety First
While traveling through the park, you may notice areas where dead beech have fallen or have been cut down by park staff. Pictured Rocks continually identifies and removes hazardous beech trees around roads, developed campgrounds and other high-use public areas.

Visitors are urged to use caution when hiking or camping in the backcountry. Be alert for standing trees that display signs of weakness such as large, dead branches. Weakened trees may fall without warning, even on days with little or no wind. This is known as "beech snap."

Be safe and pay attention to your surroundings.


Did You Know?

The light tower and flagpole of the Au Sable Light Station stand proudly.

Located within Pictured Rocks National Lakeshore, the Au Sable Light Station is on the National Register of Historic Places. Constructed in 1874, the station beacon still shines over Lake Superior's frigid waters. The lamp is now solar powered. More...