Farewell, giant pine: Climate change kills a champion at Washington Park Arboretum

One of the state’s biggest pines is headed for the saw, after climate change and bugs weaken a champion at the Washington Park Arboretum

Written by  and published in The Seattle Times the 13 May 2017

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The state’s champion pitch pine towers over David Zuckerman, manager of horticulture at the Washington Park Arboretum. The tree has died and must come down. (Alan Berner/The Seattle Times)

 

It saw the flight of Boeing’s first jet; the World’s Fair, the founding of Microsoft. It survived the eruption of Mount St. Helens, witnessed the state’s centennial, and the confession of the Green River Killer.

But after 72 years, Pinus rigida 212-45-C, the state’s champion pitch pine, has died and will be cut down at the Washington Park Arboretum.

The cause of death was climate change: steadily warming and drier summers, that stressed the tree in its position atop a droughty knoll. Red turpentine beetles, catching the scent of stress chemicals emitted by the tree as it struggled, bored in.

The beetles chewed and fed on the tree’s phloem, conduits just below the bark for the tree’s life-giving juices. Just as damaging, the beetles were vectors for fungus that plugged up other conduits carrying water into the tree. It wasn’t long before arborist Clif Edwards, making his usual rounds, noticed something amiss in the pinetum, the collection of pines at the arboretum.

“I saw this big orange (tree) canopy in the sky, got closer to investigate, and got the not-so-good answer,” Edwards said.

He alerted other experts at the arboretum, who confirmed by the plethora of exit holes about the size of the point of a crayon that the tree was badly infested with beetles. Now the tree must be removed before the infestation spreads to other trees in its grove, noted David Zuckerman, manager of horticulture for the arboretum.

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Since 2005, the arboretum has lost some 40 pine trees in just this way, as warming average temperatures combine with summer’s drought to stress trees. The arboretum has not in the past irrigated its collection of pines. But staff will begin pouring on the TLC with mulch and water this season to help its collection of stressed pines, Zuckerman said.

But for this big old pine, it’s too late. With its witchy, stark bare branches and bronze dead needles, it stands apart in the surging green of spring. It’s studded with a bumper crop of cones, each the size of a chicken egg, hard as a stone, and covered with sharp prickles. Trees near death typically put on a large crop of seeds, a desperate bid to persist into future generations.

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A close-up look at the tree shows exit holes drilled by the beetles that have killed it, along with the pitch produced by the tree to try to heal its wounds. The 72-year-old giant will be cut down sometime this month. (Alan Berner/The Seattle Times)

 

The tree’s yellowed accession card, marked with pencil and scanned for preservation in the arboretum’s digital archives, tells of its life and times. First stratified, or readied for germination by cooling a few weeks after the seeds arrived, the seed for the big pine was planted in flats on May 17, 1945, and transplanted to the nursery at the arboretum in September 1946. On April 16, 1948, it was planted atop the knoll in the prime spot in the pinetum.

In 2004, in a flurry of taxonomic activity, its name was changed from pinus nigra to pinus rigida. And all the while, the tree grew steadily on.

The tree outdistanced all others in its class, becoming the state champion in Washington of its species, at more than 70 feet high with a bigger-than-35-foot crown spread and nearly 6 feet around at its trunk at breast height.

The pitch pine’s rugged form and spiny cones belie a gentle presence. At the arboretum, this pine was graced by a bench in its shade, with a placard advising “peace” on its back. The ground in front of the bench is worn smooth by years of visitors’ feet, and the tree is just steps from the incantations of an active nest of a Cooper’s hawk and red-breasted nut hatch.

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The state’s champion pitch pine, 72 years old and more than 70 feet tall, must be removed so that the beetles that killed it won’t endanger the rest of the pine grove around it at the Washington Park Arboretum. (Alan Berner/The Seattle Times)

Visitors seem to know what is happening; someone inscribed a small purple heart in magic marker on the tree’s bark, the ink still fresh and bright from a recent visit. For the tree’s suffering is evident, in the sawdust heaped by chewing beetles at its feet, and the frass pushed out of their homes, deep within the tree’s sap wood, staining exit holes drilled all through its bark.

The tree has fought back nobly; gobs of hardened pitch, produced by the tree to seal its wounds, mound in golden heaps all over its trunk. But it was not enough.

And so the next stop for this tree is the Cedar Grove composting facility, the only way to safely and quickly dispose of the big logs that this tree will soon become.

Every last bit of the tree will be removed, even grinding the stump. Its tag — already removed, leaving the bare hook bereft in the tree’s bark — will be recycled, and the tree’s epitaph recorded in the arboretum’s saddest ledger: its Dead Plant Report.

In an arboretum boasting more than 21,000 trees, shrubs and vines in its collection, each one, for those who care for them, is an individual. Zuckerman and Ryan Garrison, plant-health specialist at the arboretum, were quiet Friday, as they examined the pine and made plans to cut it down later this month.

“I try to look on the bright side,” Zuckerman said. This pine is survived by two others on the knoll from the same gift of seeds from the New York Botanical Garden. “And this will make space for a new plant,” Zuckerman said. “Something that does not need summer water.”

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