Oak Observations March 2025
We often get questions about estimating the age of an oak based on its size. In the East Cascades, this is a tall order! An oak may remain at sapling size for up to 20 years waiting for the right conditions to expand its height. This is because oaks focus energy toward their long taproots first.
While it may look quiet on the surface, below ground oaks push a powerful, long taproot that connects them to resources. In the context of a 250-500 year lifespan, spending 20 years in this stage doesn’t seem like such a long time after all.
One way to uncover the age of an oak is through tree coring. This is a simple, non-destructive method of obtaining information about a tree's age and growth history using an increment borer (a special tool with a hollow tube and a drill bit that allows the user to extract a core sample). The core taken from this oak in the White River Wildlife Area by Daniel Leavell, helped us learn more than just the oak’s age (over 120 years old!) it helped us uncover interesting insights into the fire history of the site.
This image was taken by Daniel Leavell (pictured above using the increment borer). As you can see, the core of oak wood is very dense (typical of Oregon white oak which grow slowly). Oregon white oak wood is so hard it sometimes breaks the increment borer.
The core extracted from this oak tells a fascinating story about the area we visited. The tree rings are less than a millimeter wide, making them difficult to count. I estimate that the tree is over 120 years old. The black band near the center of the tree is a thick band of charcoal, likely the result of an intense fire that burned the tree's trunk over 100 years ago… Another key feature of the core is the presence of tiny black "stains"—three in total along the length of the core. These stains likely originated from ground fires that burned the tree with minor scorching of the trunk. They appear to be approximately ten years apart until about the last 60-80 years.
- Daniell Leavell, Oregon State University
To learn more about our region’s unique fire history, check out this fire history study led by Dr. Andrew Merschel.