iSeeChange
9:33 am
Tue August 6, 2013

iSeeChange: Fall in August?

Yellowing Aspen trees along Kebler Pass
Yellowing Aspen trees along Kebler Pass
Credit Patty Kaech-Feder

Though we’re barely a week into August, some signs of fall have started to appear in western Colorado.

On iSeeChange at the Almanac last week, Patty Kaech-Feder noticed some Aspen trees along Kebler Pass had already started turning yellow. Patty lived in Crested Butte for twenty years before moving to Paonia last year. 

“The peak season for the color change always is the second or third week of September,” she says. On a drive through Kebler Pass two weeks ago she noticed fog hanging in the air, a sight that usually tells her fall is coming. “And then the following week I actually saw leaves had changed, so I feel like we’re already in the fall mode even though it’s no it’s not anywhere near fall.”

William Anderegg, a researcher at Stanford University, says any changes in leaf color this early is probably driven by stress rather than regular seasonal changes. Anderegg studies the future of forests in the U.S. Born in southwestern Colorado, he’s particularly concerned with the impacts of drought, insects and wildfire on Aspen trees.

“There’s been a recent widespread die-off of Aspen trees in western Colorado and around the western US in the last decade,” he says. “We’ve been trying to get to the bottom of what’s going on in Sudden Aspen Decline, why are they dying, how are drought and climate change playing a role.”

He says the early yellowing Patty noticed may indeed be unusual. In a normal year, leaves start changing colors due to colder nights and morning frosts, but in drier years like this one, those changes can mean leaves are simply worn out.

“I think of it as sort of like, calling it quits for the summer because they’re so stressed,” Anderegg says. “If you’re seeing yellow leaves this early in the year, it’s certainly not this cold nights phenomenon, it’s probably more related to drought stress.”

Patty says she's also noticed changes in the wildflowers. This year, they showed up early and suddenly, all of them blooming at once.

“It just seems like there is a shift,” she says.

Anderegg says this seemingly-earlier start to fall – earlier wildflowers, colder nights and yellow leaves in August - is most likely linked to the past couple years of drought.

“This is really what we can think of as a drought of the future, a climate change-type drought,” he says. According to Anderegg, the changes Patty’s noticed are part of a bigger climate shift across the West, where early snowpack runoff in the spring and the hot, dry beginnings of summer are causing droughts to kick in earlier, and spread faster.

“This is maybe a slightly more benign signal,” Anderegg says, “but I think you don’t have to go very far on any Colorado highway to see large amounts of dead trees, which I think is a more saddening and serious effect of climate change that we’re already seeing.”

Anderegg and his colleagues are trying to predict that future by studying the current drought in detail. They created an online database similar to iSeeChange called the Drought Open-Source Ecology Project, where scientists and citizens can observe and measure drought effects in their own backyards. Anderegg hopes this kind of on-the-ground, real-time monitoring will help scientists better understand just how concerned we should be for the future of the western landscape. 

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