Colorado has approximately 50 native species of trees, but there are several that stand out as hallmarks of the state’s picturesque views.
1. Ponderosa Pine
Avid campers in Colorado have probably found themselves setting up shelter in a dry, spacious grove of these noble trees. The Ponderosa pine has the longest needle of any conifer in the southern Rockies. In the summer months, this tree can often be identified by the delightful vanilla odor given off by the resin it produces.
The Ponderosa pine has several features that make it well adapted to frequent, low intensity fires, including thick, insulating bark and open crowns. Unfortunately, past management practices have left many Ponderosa pine forests overly dense, stressed by competition for resources, and vulnerable to unnaturally large wildfires.
The health of Ponderosa pine forests is of particular concern because they are prevalent in heavily populated areas along the Front Range and play a vital role in the quality and security of the state’s drinking water supply. For this reason, Ponderosa pine forests are a high priority for restoration and management in the state.
2. Plains Cottonwood
The plains cottonwood has been called the “grand tree of the American prairies” and is the largest broadleaf tree native to Colorado. The plains cottonwood is commonly found in areas alongside streams and rivers in the prairies to the foothills. Cottonwood galleries provide tremendous benefit to both people and wildlife on the plains. Bald eagles, migratory songbirds, deer, and a variety of owls are just some of the species commonly associated with cottonwood trees. They provide important stopovers for migrating birds.
Native American tribes, explorers and early settlers made use of cottonwood trees for fuel and building materials. Cottonwood makes its presence known in spring when mature cottonwood seedpods burst open like popcorn, scattering cotton-like seeds to the wind. This release coincides with the peak of spring run-off, resulting in the seeds being carried downstream to other suitable spots for germination.
The aspen is perhaps Colorado’s most exquisite tree. Beloved by photographers for its golden foliage contrasted against pale white trunks, this tree is a true icon of the Rockies. Colorado is home to one of the largest natural aspen populations in the world.
Aspens are found in groves of tens to hundreds of trees, but what makes them unique is that the entire grove has one common, extensive root system from which the trees sprout. Because of their ability to replicate themselves with relative ease and their propensity to flourish in full sun, aspen tend to be the first trees to colonize disturbed areas like those found after avalanches, wildfires and heavy insect mortality.
Large groves of aspen can sometimes provide a natural barrier to the spread of wildfire, since they do not burn as readily as many other forests in Colorado. Aspen is one of just a few deciduous trees, and the largest, that occur in Colorado’s upper elevations, thereby adding important wildlife habitat diversity to a landscape otherwise dominated by conifers.
Visitors to Colorado’s high-elevation ski slopes will no doubt recognize both species of spruce found across the western part of the state. The blue-green hue of the blue spruce, Colorado’s state tree, is unmistakable and lends to its designation as one of Colorado’s iconic trees. Engelmann spruce favor higher, drier and more exposed slopes and produce shorter, darker cones.
Spruce forests provide important habitat to a number of subalpine wildlife species, but they are particularly critical to the endangered Canada lynx. The spruce tree’s soft, clear wood also makes it highly valued for the creation of building materials and musical instruments.
Both species of spruce are highly susceptible to fire and in many parts of Colorado they are being impacted by a severe outbreak of spruce beetles.
Junipers are recognizable by their “berries” that are actually miniature cones whose scales have grown together, giving them a spherical appearance. These berries are an important food source for birds (especially a thrush, the Townsend’s solitaire) coyotes, squirrels and chipmunks. Junipers often co-occur with pinyon pine in what are known as pinyon-juniper woodlands. These woodlands are common in dry, lower-elevation settings throughout Colorado, often providing the only forest cover in an otherwise treeless landscape. They are used extensively as wintering grounds by elk on the Western Slope and as year-round cover for elk on the Eastern Plains.
What about the ash tree?
The green ash tree isn’t native to Colorado, but it has become a standard sight in front yards and urban landscapes. It is currently being threatened by another non-native species—the emerald ash borer that has decimated ash trees on the east coast. This shiny, green beetle came from eastern Asia, and as its name suggests, it has a special affinity for ash trees.
Though the threat is relatively new to Colorado, the beetle has done extensive damage in more eastern forests. In fact, it’s recommended that measures be taken now to plant replacement native trees near ash trees in preparation for their possible demise.