Drought might affect fall foliage

by Dorothy Atkins, Aspen Daily News Staff Writer

While patches of yellow are beginning to pop up across the mountain landscape, local experts are at odds over whether the trees will change early this year due to the drought.

For Aspen’s city forester Chris Forman, the yellow leaves that have been popping up around town could be an indication of stressed trees caused by either their location or this year’s drought, he said earlier this week.

The spring was particularly rough on trees because of how dry and hot it was, and stressed trees could mean an early and possibly shorter color season, he said.

Meanwhile, the Aspen Center for Environmental Studies (ACES) has been fielding calls from out-of-towners wanting to know when the trees will peak, said Jim Kravitz, director of naturalist programs at ACES. That’s difficult to predict, he said.

A lot of things can happen with the weather between now and October that could affect fall foliage, he said.

Although conditions are still drier than normal, the rain in July and August has helped nourish a lot of the forest after this year’s unusually dry June, Kravitz said.

Kravitz is telling inquirers that the trees will peak the third week of September, which is the time it typically occurs, he said.

Changes in the length of day is the main trigger for leaves to turn. The intensity of the color change is mostly determined by the weather during the weeks prior to the day-length trigger, Kravitz said. Late August and early September rain — followed by weeks of warm, sunny days and cool, but not freezing nights, provide the most intense color — while cold and wet weather in the middle of September has the opposite effect, he said.

“No two years are alike,” Kravitz said. “While I hear some people say the leaves may change early because of drought, I have also read that dry summers might lead to a later change. All in all, I stick to the third week in September as a great time to view the Aspens.”


 Chris Council/Aspen Daily News
A clump of aspen leaves in the Maroon Bells area  turned gold earlier this week.


Still, another challenge to predicting the peak of fall foliage is that naturalists don’t have a lot of recorded data from the past detailing the timing of the changing of the leaves, Kravitz said.

There are certain species and areas that scientists have been tracking for a long time and people know a lot about, but that’s not the case with the forest in Aspen, he said. Setting up a system to track forest health specifically in the area could help naturalists predict when the leaves will change each year, he said.

“By using local examples and other people’s data along with our own, we can make the story greater,” Kravitz said.

To that end, ACES has spearheaded a program dubbed “Citizen Science,” encouraging people in the community to take pictures of certain plants and animals, and write down their locations in an effort to create an ongoing record, Kravitz said.

“With phones and cameras that have GPS on them, you can pinpoint the spot where you saw that plant or animal,” Kravitz said. “All of a sudden you have this record and this multi-level piece of data. With the right eyes comparing these things you can track trends.”

The program kicked off about a month ago with the Pika Project, which asks hikers to take a picture of a pika in the wild and email the shot, the location — GPS tagged if possible — and the date the photo was taken to pika@aspennature.org.

The pika is an ideal animal to start the program with because the species are climate change indicators, Kravitz said. The pika, which is easily spotted because of its high-pitch chirp, can only live in temperatures lower than 78 degrees Fahrenheit. Tracking pikas’ locations can help inform trends of changing climate and weather patterns in the mountains.

So far, ACES has been getting a handful of submissions from hikers, mostly tagged near Crater Lake, Kravitz said.

The program was inspired by the National Phenology Network, which brings together citizen scientists, government agencies, educators and students of all ages to monitor the impacts of climate change on plants and animals in the U.S., Kravits said.

For more information on the ACES program go www.aspennature.org/locations/hallam-lake/hallam-lake-programs/pika-project.


dorothy@aspendailynews.com