February 7, 2012

If a tree falls in the ‘forest, UW Botanic Garden arborists hear — view slide show

News and Information

Like dominoes, two of Seattles signature oaks in the Washington Park Arboretums Rhododendron Glen toppled under Januarys heavy snows.

“The 60-foot-tall canyon live oak and a smaller huckleberry oak are among the best specimens in the city according to Arthur Lee Jacobsons ‘Trees of Seattle,” said Chris Watson, arborist with the University of Washington Botanic Gardens, which oversees the plant collection in the arboretum.

The two curving, smooth trunks to the right, one of which is being crushed by the oak, belong to another prime arboretum specimen, a huckleberry oak. Both trees represent the best of their kind in the city.

UW Botanic Gardens

The two curving, smooth trunks to the right, one of which is being crushed by the oak, belong to another prime arboretum specimen, a huckleberry oak. Both trees represent the best of their kind in the city.

After careful inspection, it turned out that the root balls of each tree had not pulled out of the ground, avoiding death sentences. Watson and assistant arborist Darrin Hedberg embarked on an effort to pull the 60-foot oak, estimated to weigh more than 8,000 pounds, back into the upright position. The effort could save both specimens plus a third tree, a smaller canyon live oak that was being crushed.

“The structure and foliage of these evergreen oaks provide a unique feel to this area of the arboretum,” Watson said. “Preserving these trees was a high priority as losing them would be a dramatic loss.”

Righting a tree in the arboretum is not undertaken unless it is especially valuable to the collection and there is a good chance it can be saved, according to David Zuckerman, manager of horticulture and plant records for UW Botanic Gardens, which is part of the UWs School of Environmental and Forest Sciences. Such rescues have only been attempted a handful of times before, he said.

Using UW Botanic Gardens employees and equipment – and with the help from a number of volunteers – the four-day rescue cost $2,000 to $2,500, Watson estimated. The same operation done commercially might run $1,500 a day or $6,000 total.

Ropes, pulleys and a tractor were used to pull the canyon live oak upright so it could be supported by steel cables connected to a western red cedar, more than 60 feet tall, that was 25 feet away. As for the huckleberry oak, a minor crack in the main stem is being supported with a cable in the tree itself.

What are the chances for survival?

Watson says its a bit of a guessing game but the crew will baby the trees with mulch over their roots and enough water in the summer. It will take five years to really know if the rescue was a success.

“Rhododendron Glen where these trees are located was a place I was immediately drawn to when I first started at the UW,” Watson said.

“Its a really special place.”