Aspen leaves on track this season |

Aspen leaves on track this season

Erica Robbie
The Aspen Times
Leaves are beginning to change around Aspen, marking the beginning of autumn. Local expert Jim Kravitz said peak leaf-peeping season is Sept. 14-28 and that this year's colors should be right on schedule.
Jeremy Wallace/The Aspen Times |

Popular Aspen leaf-viewing spots

1. The iconic Maroon Bells are an ideal location to capture the splendor of fall leaves on camera. Visit the Maroon Bells page for access information.

2. Cathedral Lake, American Lake, Hunter Creek and Crater Lake are all wonderful hikes to enjoy nature’s show.

3. Scenic Driving Roads Maroon Creek Road, Castle Creek Road and Independence Pass are all available for those that prefer to enjoy the golden Aspen’s from the comfort of their car.

Source: Aspen Chamber Resort Association

It’s that time of year again, as we begin to spot bits of yellow, green and gold in the trees.

Prospective leaf-peepers call the Aspen Chamber Resort Association every summer asking for the inside scoop on local fall foliage. Aspen-area leaves draw people to the area from all over, according to the chamber.

Figuring out that perfect time to witness the changing of colors is a science — one that Aspen Center for Environmental Studies Director of Naturalist Programs Jim Kravitz knows well.

Kravitz said the peak season in Aspen is from Sept. 14 through 28, and that we are “right on track” this season.

One of the most important factors in determining when the leaves will change colors is daylight — how long days and nights are, he said.

“There’s a threshold when the switch that happens within the tree, as it stops sending chlorophyll to the leaves, it’s basically closing down its shop for the year,” Kravitz said. “If you look at the annual activity for the trees, there’s a minimal amount of photosynthesis in the bark of aspen trees. The thin bark allows them to photosynthesize, or make sugar.”

As the process starts working, the leaves are being made and next year’s buds also are forming, Kravitz said.

“So the 2016 buds are already formed,” he said. “You can look on an aspen tree right now, and those buds are there.”

This process is pretty much complete come end of June, Kravitz said, adding that they’re “already flowered” by this time of year, as well.

“Then the entire rest of the summer, the tree is doing photosynthesis just to store energy, or carbohydrates, for next year’s growth,” Kravitz said

That’s what all the production is for — the roots, the bugs and the twigs, he added.

“And then it can’t make those carbs anymore. It’s going to shut down, because it is getting into the time of year where the tree has to go dormant for a variety of reasons, such as freezing temperatures, which just isn’t efficient for them.”

Kravitz said the weekend of Oct. 3 and 4 is about the last opportunity to see the leaves changing in the high country.

“Then the cottonwoods start coming in, and town looks beautiful as ever,” Kravitz said.