Perhaps the most recognizable tree in Colorado, an aspen in the wild is only a small part of a larger organism connected by an extensive root system. In a single stand or “clone” of trees, the trees are all genetic replicas. The Pando clone in Utah’s Fishlake National Forest is the largest and oldest known aspen clone. It spreads more than 106 acres, weighs an estimated 6,600 tons, is roughly 80,000 years old, and consists of more than 40,000 trees—some more than 130 years old.

Aspens are medium-sized deciduous trees, 20 to 80 feet tall, that grow best in moist soils, with plentiful sunshine. Their trunks are three to 18 inches in diameter, with smooth thin greenish-white bark. Having moist leaves and thick twigs that do not burn easily, aspens are considered low-flammability plants, with a Low Flammability Rating of nine out of 10 (higher scores mean less flammable).

Most aspens for homeowners are dug out of the wild, with little of their root system. In the home landscape, they live at most about 25 years, and often less. Aspens are fast growing, and under the outer bark layer is a thin green photosynthetic layer that lets the tree create sugars and grow all year, even in winter.

Aspens provide year-round food for many animals including black bears, porcupines and rodents. Ungulates (deer, elk and moose) have an affinity for aspen and browse on twigs, buds, leaves and bark. They often damage lower areas of the trunk by using their hooves to help tear off bark to eat. During autumn and winter, the inner sugary layer under the aspens’ bark is an important food source, providing necessary nutrients. Also, antlered ungulates usually select trees of one-to-three-inch diameters to rub their antlers on: rubbing off velvet in early autumn, intentionally creating scars to mark territory, and removing old antlers in late winter.

Once the bark is damaged, not much can be done, but Extension Master Gardeners of Douglas County advise that adequate irrigation throughout both dormant and growing seasons is essential in aiding the tree’s recovery, especially considering Colorado’s dry climate. As the tree heals, a dark scar develops in the damaged area. Homeowners should be aware that if the damage extends around the entire trunk, known as “girdling,” it will severely compromise the tree’s ability to move nutrients and water to its various parts, making it unlikely to survive.

To help protect trees from antler damage and browsing, and thwart antlered-animals’  access to the trunk, the Master Gardeners suggest installing deterrents, including:

• Three to four stakes around trees, with or without chicken wire wrapped around the stakes.
• Tubular garden netting around the trunks of seedlings.

OR

• Some type of electric fencing.

For more information about aspens, visit nationalforests.org or csfs.colostate.edu and search “aspen,” extension.colostate.edu and search “aspens” and “aspen flammability” or visit fs.usda.gov/wildflowers/beauty/aspen, or contact Douglas County Master Gardeners at dcmgardenr@gmail.com.

 

Article by Susan Helton; courtesy photo