Washington Park Arboretum Oaks Rescued

February 7th, 2012 by UWBG Arborist, Chris Watson

Along with the constant rain and drizzle, winter in the Pacific Northwest often brings the occasional wind and snow events.  Damage to trees (and caused by trees!) is inevitable following these storms.  While wind events tend to cause the most spectacular tree failures, snow loads have been known to fell their fair share of limbs.  Damage to Arboretum trees has been lower than expected during the course of the most recent snow; however, our evergreen oak collection in Rhododendron Glen took a severe hit.

A 60-foot Canyon Live Oak (Quercus chrysolepis) uprooted, damaging another Canyon Live Oak and a Huckleberry Oak (Quercus vaccinifolia). The structure and foliage of these evergreen oaks provides a unique feel to this area of the Arboretum.  Preserving these trees was a high priority as losing them would be a dramatic loss.  In fact, the large Canyon Live Oak and the Huckleberry Oak are listed among the best specimens in the city in Arthur Lee Jacobson’s Trees of Seattle.

The tall Canyon Live Oak has an interesting history, as well.  Plant records indicate that this tree was grown from seed collected by Carl English Jr., for whom the botanic garden at the Ballard locks is named.

After a careful inspection, no root decay or extensive damage was observed on the large Canyon Live Oak.  Through the use of ropes, pulleys and a tractor, the tree was pulled upright, and supported by cables to a nearby tree.  After carefully installing a couple of braces, or steel rods, the smaller live oak will be spared a severe pruning.  As for the huckleberry oak, a minor crack in the main stem will be supported with a cable.

News stories following winter storms are often portray trees in a negative light.  However, through proper care and maintenance, most trees can withstand our seasonal storms.  Sometimes, when given a chance, the trees that receive the brunt end of Mother Nature’s fury can be given a new lease on life.  After all, trees are not only a vital component of our urban forest; they are one of our regions defining characteristics.


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Boyer Parking Lot Tree Protection

May 2nd, 2011 by UWBG Arborist, Chris Watson

One of the most widespread problems with trees in the urban environment is the failure to recognize the tree’s mature size.  If one doesn’t take into account the space required when the tree grows up, conflicts are sure to arise.  To make matters worse, the tree is often faulted for encroachment!

Several trees surrounding the Arboretum’s Boyer Parking Lot have grown up and encroached on the gravel parking spaces.  However, because we are advocates for the trees, we decided to make the parking lot yield.  A large scarlet oak (Quercus coccinea) and a grove of birch (Betula) were severely impacted by the concrete wheel stops and compacted soil over a large portion of their roots.  To remedy the problems, we moved the wheel stops to create a “root protection zone” around the trees.  Then, we used compressed air tools to break up the compacted gravel and soil.  We amended the soil with mycorrihizae and compost, then topdressed with a thick layer of mulch.  If all goes as planned, the additions will stimulate the soil biology, add nutrients and allow roots to grow in the previously uninhabitable environment.  Stay tuned for updates.

 

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