The Weekend Warriors of Centennial Woods

Rare Care
Jon and Martha Diemer, the weekend warriors of Centennial Woods.

Since the initial planting of Centennial woods in Union Bay Natural Area in 2007, in celebration of the first 100 years of the College of Forest Resource (now known as the School of Environmental and Forest Sciences), Jon Diemer and his wife Martha have become the weekend warriors. They devote every free Saturday to restoration work at the site. As the current UBNA Ranger, I was able to lend a hand and plant a few hemlocks and shore pines this past Saturday, January 16th, 2016. Along the way I learned about this great site.

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Jon doing a planting demo with a Western hemlock, Tsuga heterophylla.

Trying to find Centennial Woods? Centennial Woods is located on the western edge of UBNA, across from the former E-5 parking lot. (Labeled in green.)

CW map

Restoration work at Centennial Woods requires patience and perseverance because the site is threatened by tireless invasive species such as Himalayan blackberry, and also high mortality rates of planted trees. For example, from the initial school sponsored planting in 2007, only 40 of the original 400 bare root trees survived. The trees have also had some run-ins with mowers. A challenging site like this requires constant management to reach restoration objectives.

Despite having finished his Masters of Environmental Horticulture project and returned to a full time job other than managing UBNA, Jon has continued researching the best ways to control Himalayan blackberry and promote survival rates of the planted trees. Jon is trying out the efficacy of herbicide to control patches and shading out patches with a tarp (pictured below).

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Herbicide trial to eliminate blackberry.
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Shade trial to eliminate blackberry.

To increase survival rates, Jon is trying out different plant species native to more southern climates including redwoods from California! You can see one little redwood doing well in the picture with Martha and Jon. Species adapted to more southern climates are predicted to do well with the warming temperatures associated with climate change.

There are more trees that need to be planted this winter. If you are interested in helping out please contact me, Anna at or Jon at

For more information, check out Jon’s MEH thesis Centennial Woods Restoration and Management Plan.