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Fears that juniper trees across Southwest Colorado were headed for a massive die-off did not materialize this summer, but the fate of the hardy tree throughout the Four Corners is still in serious question.

“I thought they were all going to die,” said Gretchen Fitzgerald, a forester with the U.S. Forest Service’s Columbine District. “But they all came back, for the most part.”

This past winter, junipers in Southwest Colorado started turning from green to a rusty bronze color, perplexing foresters in the region.

Normally in the winter, junipers turn a hue of purple as the tree shuts down its system in a sort of plant-induced hibernation to save energy and resources.

But last winter’s discoloration of junipers had not been seen in seasons past.

In the 20 years she’s worked in Southwest Colorado, Fitzgerald said she’s never noticed junipers take this kind of turn. Her colleagues around the region, too, said it was a first.

“I got emails from all over the state saying the same thing is happening here,” Fitzgerald said.

From the outset, beetle kill and disease were ruled out, leading foresters to believe the discoloration was somehow related to extreme stress caused by drought conditions and wildly fluctuating daytime and overnight temperatures during the winter.

Adding to the confusion, however, was the fact the junipers weren’t showing the usual signs they were dying. And, it’s ecological neighbor, the less drought-resistant piñon tree, wasn’t showing any signs of stress.

“If anything is going to survive the drought around here, it’s going to be those junipers,” said Mark Loveall, Durango supervisory forester for the Colorado State Forest Service. “They’re about as tough a tree as you can get.”

All foresters could do was wait and see how the junipers would progress over the spring and summer.

Inexplicably, and fortunately, over the past months, the junipers recovered and returned to their natural green color.

Fitzgerald said she started to notice the junipers along U.S. Highway 160 between Durango and Bayfield and up toward Hermosa turn green after it started to rain in the spring.

The trees continued to show healthy signs over the summer, despite the relative lack of precipitation, she said.

“A couple died – the ones that had turned really brown,” Fitzgerald said. “But the ones that turned orange turned green again.”

Dan West, an entomologist with the Colorado State Forest Service, said a survey of junipers around Dolores and Mancos in August also came back with the same positive results.

“Everything looked green and just fine,” he said. “We just haven’t seen any further issues with junipers.”

What caused the junipers to turn brown in the first place, and what led to the junipers to return to normal, remains a guessing game.

Southwest Colorado received some rain over the summer, but the region is still in an exceptional drought. Since Jan. 1, a weather station at the Durango-La Plata County Airport has recorded just 4 inches of rain.

That’s more than 7 inches below normal.

Fitzgerald speculated that last year’s hot and dry winter caused the junipers to shut all the way down. Then, when modest rains did fall over the spring and summer, they rebounded.

West said perhaps the discoloration was connected to a late spring frost in May 2017, and the trees didn’t show the effects until that following fall. Or, maybe it was just some reaction to the prolonged drought.

“I’m just not real sure,” West said. “We didn’t set up any permanent plots for monitoring, so there’s no data to back it up, other than anecdotally.”

The outlook for junipers across the Four Corners, however, isn’t so encouraging.

Monica Gaylord, a forest entomologist for the U.S. Forest Service based in Flagstaff, Arizona, said there have been reports of massive juniper die-off all over Arizona and Utah.

And no one knows why.

“All of a sudden the junipers are just dead,” she said. “And in all honesty, it’s a mystery right now.”

Junipers in these states didn’t show that bronzing discoloration like they did in Southwest Colorado, Gaylord said. Instead, the trees just started dying this summer.

And there seems to be no historical precedent for the die-off, she said.

During the last major drought in 2002, foresters noted significant piñon mortality, but the junipers made it through fine. This year, piñons aren’t showing any signs of stress, Gaylord said.

The juniper trees are also showing no signs the deaths are related to beetle kill or disease.

“We’re just not really seeing a smoking gun,” Gaylord said.

A recent report in the San Juan Record said junipers around San Juan County, Utah, have been dying off by the thousands in areas around Cedar Mesa, Muley Point, Alkali Ridge and Muley Canyon.

The cause there, too, is unknown.

“There are miles and miles of dead trees,” Kay Shumway, a retired botanist, told the Record. “This is killing the little guys who are by themselves, the nice beautiful young trees, and the old timers are going also.”

Shumway did not return The Durango Herald’s request for comments. Calls to foresters at the Utah Division of Forestry were also not returned.

Gaylord said foresters will conduct a flyover of piñon-juniper woodlands in the coming weeks to survey the health of the forests. It’s likely more monitoring and research will go into junipers if the situation worsens.

jromeo@durangoherald.com