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brown smudge on black butte ???


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the last few months I have noticed a (growing?) horizontal band of dead trees at a mid elevation on Black Butte near Sisters. It seems very confined to a specific elevation on the south face of the butte. Anyone know what this is? I looked at fire data and there weren't any fires/controlled burns there recently. Beetle kill perhaps? seems a little weird that it is so rampant in such a confined elevation and hasn't spread vertically on the slope. I'll try to get some photos next time I go out. It is very obvious while driving east on hwy 20.

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hrm, found this, perhaps the same phenomenon with the cold snap in dec.?

 

"In February of 1950 Black Butte once again became the center of local attention. But this occasion was due to the hand of Nature and not a scheme generated by humans.

 

Winter's low setting sun revealed a strange golden band wrapped around the butte's southwest slope. Forest Service personnel from the Sisters Ranger District reported that the band was three miles in length and three- quarters of a mile wide. The gold strip stretching across the bright green background of trees was spectacular when viewed from the Santiam Highway below.

 

Sisters Ranger District spokesman Harold Gustafson explained that the color of the band was produced by sunlight hitting dead, brown pine needles. Prior to the phenomenon, the area was gripped by extremely cold temperatures, which caused the needles to dehydrate. A thin stratum of very warm air then moved in and crowded out the cold air in the area of the band. This sudden increase in temperature burned the needles.

 

The needle kill was considered extensive and affected mature as well as young trees. Foresters believed that no long term damage would occur, but they were concerned that there would be significant secondary damage if pine beetles attacked the weakened trees. The gold band remained visible throughout the season."

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Bulletin ran a story about it today.

 

 

About that ring around Black Butte: Experts say...

Weather may be cause of rare phenomenon known as ‘red belt’

By Kate Ramsayer / The Bulletin

Published: May 29. 2009 4:00AM PST

 

Something a little odd has appeared on the slopes of Black Butte and a few of its neighbors.

 

Midway up the butte west of Sisters, a distinct stripe of rust-colored trees has appeared between the evergreen pines.

 

While it might look like some deadly tree disease swept through a swath of forest, the trees aren’t dead — instead, it’s just the needles that have shriveled up and turned rusty. The likely culprit is a combination of weather events — including temperature, sunlight and wind — but foresters are still trying to pin down what exactly happened.

 

“We’re still trying to piece it together,” said Stephen Fitzgerald, forester with the Oregon State Extension Service in Redmond.

 

The stripe of rust-colored trees on Black Butte, between 4,400 feet and 4,600 feet in elevation, is called a “red belt,” he said, a rare phenomenon in Central Oregon.

 

But this year, Forest Service silviculturist Brian Tandy has spotted a belt across Black Crater in the Three Sisters Wilderness, as well as Green Ridge in the Metolius River Basin.

 

All have the same characteristic swath of rust-colored pines, which is caused when needles lose moisture and dry up.

 

That can happen when the roots of a tree stay frozen in cold soil while its needles thaw. They thaw when they’re exposed to warmer temperatures, direct sunlight and the right winds, and then come out of their winter dormancy and start cranking up the plant’s energy-producing machinery.

 

During one step of that process, needles release moisture through microscopic holes. Normally, the lost moisture is replenished by water the tree takes in through its roots, Fitzgerald said.

 

But when the roots are frozen, the water stops flowing, and the needles’ water supply is shut off.

 

“The needles would desiccate or dry out,” he said.

 

That doesn’t mean the tree itself has died, however, Tandy said.

 

While some of the trees on Black Butte might look pretty bad, some of the needles are still green and can still photo-synthesize to churn out the energy needed to support the tree.

 

And the buds on the tree are still alive and green, so in a while, Tandy said, the dead needles will simply fall off, and new green ones will replace them. “It could take a year or two for it to sort of fade away,” he said.

 

The question that still puzzles foresters, Tandy said, is what caused the red belt in the first place.

 

“It’s hard to know what actually caused it,” he said. “To me, it feels like it might be more associated with an inversion.”

 

An inversion — a weather event in which cold air is trapped below a layer of warm air — could have caused the needles to come out of dormancy at a certain elevation, he said.

 

An inversion before Christmas could have done the trick, he said, causing the trees to start turning to the rust color in January.

 

Jack Barringer, a retired forester who lives in Black Butte Ranch, did a little sleuthing of his own to try to find the red belt’s cause.

 

He searched weather records from Sisters and the Hoodoo ski area to look for inversions, and went online to check the precise angles at which the sun’s rays hit Black Butte’s slope throughout the winter.

 

His candidate is an inversion that occurred during the middle of January, he said, bringing a fog bank over the bottom of Black Butte.

 

Temperatures under the fog bank were cool, but above it the air was warmer than usual, he said. And the sun’s rays could have bounced off the top of the fog, heating the air surrounding ponderosa needles even more, he said.

 

Barringer attributes the band’s sharp upper edge to snow and ice that perhaps clung to needles above a certain elevation, preventing the needles from warming up.

 

“It’s just a rare occasion; the weather has to be just right,” Barringer said.

 

And it doesn’t often happen in Central Oregon.

 

Forest Service employees who have worked in the area for about 40 years have only seen red belts a couple of times, Tandy said, adding that he’s only seen it once before.

 

It takes more than just an inversion, he noted.

 

“We have inversions all the time, and nothing like that happens,” Tandy said.

 

Instead, he said, it has to be a combination of events like an inversion, strong sunlight and maybe winds that blow across the needles, drying them out even more, “like the perfect storm.”

 

 

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