Know Your Trees - Aspen

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Quaking aspen is the most widespread and numerous hardwood tree in North America. The scientific name Populus tremuloides is translated into “poplar that trembles” (or "quakes" in the case of aspen). It is known for its white bark and leaves that tremor in even the slightest breeze. It is also known for its spectacular yellow color those same leaves turn in the fall. It is those leaves when they turn yellow that provide so much of our fall color when they change. Those areas will become islands of golden aspen in a sea of evergreen trees. 

Aspen are unique plants. They have a life history unlike any other tree. Every tree in an aspen stand is often connected to a single root system. They spread through underground roots with new trunks growing up from the roots. So, every tree in a stand may have the same genetics. Because of this, aspen groves are often referred to as clones. Trunks may live for a hundred years, but the root system may be hundreds or thousands of years old. Under the right conditions, a single aspen clone may cover over a hundred acres. According to the US Forest Service, one clone in Utah was found to be 80,000 years old, although 5,000 to 10,000-year-old clones are more common. As a result of this unique biology, some experts say that aspen are the oldest and largest living things on earth. At the very least, they challenge our understanding of an individual organism. As a result of this growth pattern, aspen are highly resistant to many types of disturbance. If an individual trunk is attacked by disease or insects or is killed by a fire. It will grow back quickly from the extensive root system. When these events happen, the trunks release stress hormones, which, in turn, cause buds in the root system to start growing. This strategy and fast growth rates allow aspen to recover quickly after a wildfire. Fire is used to promote aspen growth and reproduction. Prescribed fire is an important tool in managing for aspen. Because aspen is adapted to fire and other disturbances, in this way, it does not do well in the shade of evergreens and prefers to be in the full sun. In addition to prescribed fire, the refuge complex staff often remove pine and fir growing in amongst and next to aspen to get them the sun they need to thrive.

Because they grow so fast, aspen is among the softest wood of the trees collectively known as hardwoods. This feature makes it a preferred tree for many bird species, especially those that need to carve out cavities to nest in. Woodpecker species like flickers and sapsuckers prefer to nest in aspen when possible. It is a fast-growing tree, which means the soft new growth is abundant and produces lots of sugars, making it a staple for mammals like elk, moose, deer, and beaver. Those soft leaves are exceptionally nutritious compared to most of our other trees' hard and acidic pine needles. Their leaves are a favorite of numerous insects, which in turn are fed on by warblers, flycatchers, and many other birds. These properties make aspen one of the most important wildlife trees on the Inland Northwest Complex.

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Deciduous trees
Flowering plants
Wildlife refuges