Recent Outbreak of Sudden Death

in oaks in the Chesapeake Bay region: Bay Journal, Oaks are dying at record rates across Chesapeake region

It’s not your imagination. Those beautiful mature oaks are dying — along the road, in forests, perhaps even in your yard — at an accelerating rate.

Reports of mature, seemingly healthy trees suddenly becoming leafless and dropping dead branches are flooding into the offices of local officials and state forestry agencies in Chesapeake Bay drainage states. Forest inventories show the oaks are declining in Pennsylvania, Virginia and Maryland.

In Anne Arundel County, MD, county officials received so many phone calls about dying oaks that they have begun investigating where and why so many are perishing.

The rate of loss worries forest managers and arborists across the region, prompting efforts by state and federal agencies to understand and slow what they have labeled “oak decline” — which appears to have no single or predominant cause. While studies of the die-off are underway, forest managers have launched long-range efforts to nurse survivors and replace the dead.

Their concern is based both on the unsurpassed importance of oaks to wildlife and forest ecosystems, as well as the commercial value of their wood.

With about 20 species in Bay states, oaks are acknowledged as the most beneficial trees for wildlife. Acorns are food for more than 100 species of mammals, including deer, turkeys, squirrels, mice, birds and others. Migrating songbirds rely on them, feeding on insects spread under their broad canopies. Hundreds of species of caterpillars feed on oak leaves.

Even their fallen leaves support more insects than other trees, curling on the ground and decomposing more slowly than other leaves, offering an umbrella of shelter. The leaves of most trees fall flat and are plastered to the ground.

In urban neighborhoods, oak trees are valued for their wide, shading canopies, ability to filter water and, more recently, their absorption of carbon dioxide, a major greenhouse gas.
No single culprit

Experts say that oak decline is accelerating and that the causes are complex and cumulative. They include extreme weather from climate change, above-ground and subterranean diseases, insects and the current infrequency of fires that oaks evolved to tolerate, giving them a competitive advantage in post-fire environments.

“People are tired of [vague] answers, but it’s not a single insect or disease,” said Dave Clement of the University of Maryland Extension.

Then there is the sad reality that many oaks are simply ending their lifespan somewhat in unison.

Oaks became the dominant tree in eastern North American forests after a blight wiped out American chestnut trees in the 1920s and 1930s. Controlled burning and the clear-cutting of forests was common. Oaks, which evolved not only to be tolerant of fire but also to thrive in abundant sunlight, prospered in the new gaps in the forest.

Now, many of those old monarchs are giving up the ghost around the same time. The older trees are more vulnerable to disease, insect infestation and the ravages of extreme weather, noted Lori Chamberlin, forest health manager for the Virginia Department of Forestry. They can be declining for years, even decades, before telltale leaf diebacks are noticed.

“Trees don’t live forever,” Chamberlin said. “In Virginia, we just have a cohort of trees reaching this advanced age at the same time.”

As I noted before, we recently had a mature White Oak in our back lot fall over, barely missing our new fence. While it was still alive (at least it had some leaves last year), the root area clearly had some rot. It may have been negatively impacted by the building of our house over 30 years ago, its roots were just about at the edge of the pad built up for the foundation, and may also have been affected by our septic tanks, which is under the yard not far away. Or maybe it just succumbed to disease and old age naturally.