“Did you see the aspen grove?” my colleague asked me after we finished our walk at Killin Wetlands Natural Area about four miles west of Banks.
“Yes!” I replied excitedly. Though obscured in a cocoon of cottonwood and Douglas firs, I could see the telltale shimmering leaves of quaking aspen.
Public access coming soon
There’s currently no formal public access to Killin Wetlands, but improvements in the works will allow visitors to experience a portion of the site starting in 2017.
The plan calls for 20 parking spots, an overlook, viewpoint and other amenities. A boardwalk is included in a future phase.
For years, devoted birders heading to Killin Wetlands parked on the side of Northwest Cedar Canyon Road and set up their scopes on the roadway. The upcoming improvements will improve safety by providing visitors with access to a portion of the 590-acre site, while also restoring habitat. The area around the aspen grove is leased for farming and is not part of the planned improvements.
In recent months, trails were laid out on the ground. Improvements to stabilize the barn are also underway, with repairs to the siding, windows, roof and doors, along with a fresh coat of paint. In the coming weeks, a colorful new addition will debut on the barn: an 8-foot square, wooden block that will be a part of the Quilt Barn Trail of Washington County.
The access improvements are paid for with money from the voter-approved 2013 parks and natural areas levy.
Quaking aspen is the most widely distributed tree in North America, but it is rare in western Oregon. With the conversion of floodplains to farmlands and other changes over the last 150 years, many Willamette Valley aspen groves were lost, diminishing the biodiversity of the valley. The aspen forest at Metro’s Killin Wetlands is one of several small groves scattered on the floodplain of the west fork of Dairy Creek, and I was excited for the chance to restore this rare native habitat.
When I first walked this aspen woodland two years ago, it was in steep decline. Aspens are sun-loving trees. But the aspen grove at Killin Wetlands was losing out to Douglas firs and black cottonwoods, both of which grow taller
and faster than aspens. In the absence of fires or other natural disturbances, the firs and cottonwoods started overtaking the aspen grove.
Fortunately, the remedy was easy. Let’s strategically remove the Douglas firs and cottonwoods to allow the prolific sprout-producing aspens to fill in the newly created gaps, I recommended.
In spring 2015, Metro staff and consultants walked through the forest many times to fine-tune our restoration strategy for this unique habitat. As summer passed, we strategically cut and removed trees overtaking the aspens.
Early this spring, I visited the aspen forest again in hopes of finding hundreds or thousands of new aspen clones. I was surprised to find that most of the regeneration looked like cottonwoods, a closely related species. The
leaves were more triangular instead of the oval-shaped leaves of aspens, and they lacked the thin, flat stems that make aspen leaves tremble in a light breeze.
Relax, my colleagues told me, these are just what young aspen look like. I was skeptical and a bit disappointed. Could we have done all this work to promote aspen only to end up regenerating cottonwood?
It turns out that aspens have a strong ability to alter the shape of their leaves. This wonderful trait allows aspens to assume different leaf shapes that allow for improved photosynthesis, the process by which plants convert sunlight
to energy. The adaptation provides an advantage for survival in unpredictable growing conditions.
I celebrated as the summer passed, as many of the young sprouts took on the more typical leaf shape and flattened stem of the quaking aspen. It turns out the thinning promoted both aspen and cottonwood. Autumn will be a little more colorful this year when the golden glow of the expanding woodland turns on.
Why are aspens so special?
Quaking aspens have some unusual characteristics that explain their success across North America. Although aspens can reproduce by seeds, the environmental conditions in Oregon result in most aspens growing through a process called vegetative reproduction. The trees share a root system, and genetically identical clones grow upward into trees called ramets. The shared root system allows thousands of trees to share water and nutrients.
It also gives aspens an advantage in surviving fires, floods and landslides, because they can rely on trees and roots in other parts of the expansive network. Often, aspens are the pioneers after fires or landslides, blanketing the land with tens of thousands of root sprouts.
Unlike the bark of other trees, the white or sometimes green-tinged bark of aspens is living tissue capable of photosynthesis – converting sunlight into energy. This feature gives aspens a boost even in low-light levels and during winters when the trees are leafless.
The conspicuously delightful trembling of the leaves is possible because of the flat shape of the leaves and stems. The slightest breeze ignites a shimmering canopy of greens or, in autumn, spectacular yellows and reds.