How do you care for a 500-year old oak tree?

I’ve been fortunate to help care for some very special trees. When I worked for Maryland DNR, I helped care for the Wye Oak in Wye Mills, MD, which stood for decades as the National Champion white oak (the largest known white oak in the US). I was also around when that grand tree came down in a storm in 2002.

From the Baltimore Sun

Me and the Wye Oak when it fell – From the Baltimore Sun

When a large veteran tree is at risk of failure, you have a few options:

  • You can remove risk by removing the tree
  • You can mitigate risk by treating the site and moving potential targets
  • You can mitigate risk by treating the tree

With a great historic tree, removal is thankfully most often not an option. You may be able to move some targets, but if roads, buildings, and other infrastructure are at issue, those options may be limited. Treating the tree is often the primary option remaining. The tree had massive decay in the base. Support systems and a pruning prescription to bring the weight of the crown down and in bought some time, but eventually nature took its course.

In the case of the Wye Oak, the targets that could be moved (benches, paths, etc.) were moved. John Ohler, the MD DNR Park Manager charged with primary care of the tree, did an amazing job and when this giant tree fell there was virtually no property damage.

Here at SavATree, we have provided care for the Bedford Oak, a historic oak tree in Westchester County, NY, since 2000. Following a large branch failure in 2013, we undertook an examination of the tree. This examination included: aerial inspection of the tree with measurements and photographs of conditions and items of concern; data collection with TreeRadar™, the most advanced non-invasive diagnostic tool available; review of our maintenance records for the tree and consultation with our arborists that have provided direct care for the tree since we began maintaining the tree in spring of 2000; and, review of the results of all of the above with conclusions and recommendations by a team of experts including the Certified Arborists that have provided ongoing care for the tree for over a decade and three Registered Consulting Arborists who are service line directors for our Tree Care, Plant Health Care, and Consulting programs. Unfortunately, we found a tree whose defenses are compromised, evidence of inability to successfully compartmentalize injury at multiple locations, and incipient decay in the main stem at the top and at the base.

Nick in tree

SavATree’s Nick Bomber probes and measures an open cavity in the main stem of the crown of the Bedford Oak. The cut above the decay shows no compartmentalization. TreeRadar analysis indicated early stage saprot in this area as well as at the base of the tree.

Veteran trees are large structures that weigh many tons. They self-optimize by maximizing energy capture potential (leaf surface) for minimum structural cost (wood) (Mattheck and Breloer, 1994, the Body Language of Trees). Long-lived trees will reconfigure their crowns over time for the sake of efficiency as is described here. Veteran oaks with a long lifespan are described as having three phases: developmental (0-300); mature (300 – 600); and, ancient (more than 600). A tree transitioning from the mature to the ancient phase will be expected to shed parts to reconfigure its crown for the final phase. When trees retrench and reconfigure their crowns, they self-optimize by shedding pieces that have become too “expensive” from a resource allocation standpoint. This is a natural process. When we put roads beneath trees and invite people to sit under trees during this process, quite natural but entirely undesirable things happen to persons and property.

The prescription we recommended for care of the Bedford Oak is similar to one recommended and implemented to care for Maryland’s Wye Oak. That tree faced certain issues similar to those facing the Bedford Oak. Those recommendations were similarly derived by review of the tree’s history, aerial inspection and data gathering, and collective review by a team including national and local experts. Unfortunately, the Wye Oak’s prescription was not developed until its decay situation was critical. The Bedford Oak is much better positioned.

If you have a veteran tree to care for, I encourage you to perform due diligence and engage a variety of experts that have experience with veteran trees, both standing and fallen, and in a variety of locations.