A tall, stately oak tree grows outside of my kitchen window that I enjoy watching through the seasons.  I watch as buds burst open in the spring, grow into a lush, green canopy under the summer sun and change from green to brilliant red in the fall. I see from my window squirrels racing along its trunk, birds perching on its limbs with a song, woodpeckers pecking, and acorns ripening and falling to the ground with a thud, a world unto itself.  But this year I noticed a change in my stately oak tree.  This year my oak tree is missing leaves along its fringe and the tips of her branches are bare.  This is a sign of stress.  This is a sign of Oak Decline Syndrome, a condition where oak trees decline in health for several years before they die.

For centuries, oak trees have dominated the forests of the Eastern United States. In recent years populations of many oak species have dramatically declined. Many oak trees in Virginia are aging, with a large number of mature trees reaching similar ages due to past forestry practices. Older trees are less resilient to stressors. Finding young, mature oaks is increasingly difficult, leading to concerns about the future of oak-dominated forests in the state. 

No single factor is responsible for what is generally defined as oak decline.  Invasive pests, drought, fire suppression, and soil compaction from human activities are among the primary factors of oak decline in our region. The infrequency of natural fires, which historically cleared competing vegetation and favored oaks, contributes to the success of other species. High deer populations consume oak seedlings, preventing them from establishing into mature trees.  Invasive plants and other species, such as red maple and tulip-poplar, are increasing in abundance and volume, outcompeting young oaks for resources. Some timber harvesting methods, like selective cutting, can inadvertently create conditions more favorable for competing species to grow. 

Why does this matter?

The loss of one oak tree is the loss of an entire ecosystem. Oak trees, often referred to as a keystone species, provide critical habitat to upwards of 2,300 species, from insects and birds to fungi and lichens. Oaks host the greatest diversity of caterpillars among North American trees. One study documented over 530 species in the Mid-Atlantic region alone.  Oaks also support a wide range of beetles, treehoppers, leafhoppers, and gall-forming insects, along with their predators and parasites, and over 100 species of fungi. Owls, woodpeckers, chickadees, and Eastern Bluebirds are examples of birds that utilize oak cavities for nesting.  Warblers, vireos, and thrushes forage for insects in oak woodlands during migration. Oaks offer shelter and a crucial food source (acorns) for a variety of mammals, both large and small. Deer, squirrels, mice, raccoons, opossums, and even bears rely on acorns.  Bats roost in tree cavities and porcupines feed on the bark. 

The collapse of an ecosystem leads to a gradual process of degradation that is less biodiverse and less able to support life. This degradation is evidenced by deforestation, pollution, soil erosion, and a depletion of natural resources, which ultimately harms both the environment and mankind. 

What can you do?

There is no cure for oak decline. The best course of action is to take preventative measures to keep oak trees healthy. The National Park Service offers several steps you can take to keep your oak trees healthy and reduce the risk of oak decline in your oak trees:

• Removing invasive vines from trees
• Avoiding damage to tree limbs, trunk, and roots
• Monitoring trees for insect pests and fungal and bacterial infections
• Pruning damaged/diseased limbs
• Mulching around the base of trees to protect roots
• Watering trees during dry spells and limiting pesticide use
• Consulting with local forestry experts and ISA Certified Arborists for advice and assistance on tree-related issues

Make conditions favorable to oak trees on your own property.  Ensure that your city or town supports and protects oak trees growing on the common land.  Support sustainable forestry practices and forest health monitoring programs offered by the Virginia Department of Forestry.  For concerns about specific trees, it is best to consult with a certified arborist or your local Virginia Cooperative Extension office for expert advice fitted to your situation. 

“Watching your treasured oak tree slowly die is difficult, but the time for applying preventative measures has likely passed once your tree has lost more than a third of its canopy,” warns Fairfax County Public Works and Environmental Service on oak decline. “Be cautious of treatments that promise to reverse or stop oak decline. At best they will only delay the tree’s inevitable death.”

Nancy Sopher is a newly-certified Virginia Master Naturalist.  She received a BA in Journalism from the University of South Carolina and enjoyed a long career in advertising and marketing before retiring to Central Virginia in 2016.  

(Reprinted with permission by the Piedmont Journal Recorder, an online news source covering local news in Greene, Madison, Orange and Rappahannock counties.