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October 2004

Farewell to a well-loved tree

The ponderosa in its healthier days.

A stately ponderosa pine tree, encircled by a walkway from the Mesa Lab to its parking lot, has been a living symbol of NCAR's sensitivity to the natural environment ever since the lab was built. For more than 40 years, passers-by have paused to savor its unique beauty and perhaps to appreciate the care that preserved it. Now, it's time to bid the tree goodbye.

"It's been such a part of the look and folklore of the building," says Diane Rabson, NCAR archivist. Although Diane could not confirm it, there's a story that Walt Roberts, NCAR's first director, asked architect I.M. Pei to save the tree by curving the sidewalk. Roberts and Pei even gave the tree a name: Old Jake.

Despite the founders' love for this tree, the Mesa Lab itself is at least partly responsible for its death—although this could hardly be considered an untimely demise, since Old Jake was nearing the end of its natural lifespan of 150-200 years. Ice-melt chemicals used on the stretch of walkway between the lab and the tree all run off onto its roots. The walkway also reduces the tree's access to surface moisture. The drought of 2002 may have dealt the death blow, but "according to the experts we have consulted, that tree has been dying a slow death for 45 years," says John Pereira (Physical Plant Services, or PPS). Runoff from a major glycol spill in the traffic circle last year only made matters worse.

John and his colleagues considered leaving the dead tree where it is to serve as habitat for many species of wildlife. But unfortunately, the first species to move in was the pine beetle, an insect pest that carries a tree-killing fungus. "We've learned that they're almost like a predator," says Dave Maddy (PPS). "They cull the weak and diseased trees." Healthy trees are able literally to pitch the insects out in a ball of sap, but many of the mesa's already stressed ponderosas are not strong enough to repel a beetle attack.

The beetle colony has already laid its eggs in the tree. "Sometime next year, between July and September, the beetles are going to emerge from Old Jake and attack the nearby trees," says John. "We choose not to sacrifice those trees." So the dead tree will be removed as soon as possible—probably this fall—and the beetle-infested wood disposed of properly. Some other dead trees will also be taken out, including a small clump near the lab.

Even with the dead trees removed, John explains, the mesa site is overpopulated with ponderosas. According to Allen Owen, Colorado State Forest Service district forester for Boulder County, a healthy density for the pines is 20-60 square feet of tree trunk per acre (a mature tree with a diameter of 3 feet has about 7 square feet of trunk); the density on the mesa is 80-100 square feet. The excess trees reduce nutrients available to other plants and increase the fire danger. "We need to do the things necessary to create a more natural habitat that will promote healthier trees," says John.

To that end, Owen and Anne Armstrong, plant ecologist for the City of Boulder, have recommended that a 10- to 20-year management plan be created for the mesa site. The plan will probably include an ongoing series of controlled burns, both to reduce the danger of wildfires and for control of noxious weeds such as knapweed, Canada thistles, and leafy spurge. The NCAR staff have contacted Anchor Point, a Boulder-based forest management consultant recommended by the state and local experts, to begin the process.

What will fill the hole left by Old Jake? Perhaps a bench, or interpretive signage about the ecosystem, or even a memorial for the majestic tree. But there's one thing that definitely won't replace Jake: another ponderosa. John notes, "We couldn't get another tree to grow there."

If you have any questions about Old Jake or the long-term plans for managing the mesa, please contact John at 303-497-1128 or pereira@ucar.edu.

Carol Rasmussen


Also in this issue...

Freezing drizzle: An aviation hazard that's no longer hard to see

Hurricanes and climate change: Is there a connection?

Paul Swarztrauber looks back on 41 years at NCAR

Digital Image Library now easily accessible

Delphi questions

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