Colorado's Forest Types
With its diverse mix of coniferous and deciduous species, Colorado’s forested landscape is, perhaps, one of the most complex of any in the Intermountain West.
Ecoregions in Colorado
The basis for this vegetation mosaic is a physical landscape that ranges from plains and high plateaus to steep mountains, deep canyons and sloping foothills. A wide range of topographic, soil and growing conditions further influences this variety and contributes to the state’s multi-faceted forest resources.
Issues and events that influence forest condition often occur across forest types, ownerships and political boundaries. As a result, scientists, researchers and land managers must also find a way to assess and treat these issues in a boundaryless way. Ecoregions often are used as a non-political land division to help researchers study forest condition. An ecoregion is a large landscape area that has relatively consistent patterns of topography, geology, soils, vegetation, climate and natural processes (Shinneman et al 2000)1. Many smaller ecosystems may reside within an ecoregion.
Colorado contains parts of six major ecoregions (Bailey 1995)2. The most prominent is the Southern Rockies, which occupies most of the state's central and western portions and the Great Plains-Palouse Dry Steppe in the eastern half of the state. Other ecoregions include the Intermountain Semi-Desert and Desert, the Nevada-Utah Mountains and the Colorado Plateau. Forests are found in all ecoregions of the state, but the Southern Rockies contain the most forested area and the greatest variety of forest types.
Forest Types Overview
Forest type, or forest cover, refers to the dominant tree species in the overstory of a given site. The distribution of forest types across the landscape is determined by factors such as climate, soil, elevation, aspect and disturbance history (Rogers, et al, 2001)3. A number of Colorado's forests are characterized as disturbance driven. The life history of these forest types evolved with a cycle of natural disturbance such as wildfire, insect infestations, flooding, avalanches, windstorms or disease infections. These disturbances served to periodically rejuvenate forests, ensuring a variety of forest types, age classes and densities across the landscape. Due to lack of disturbance, the majority of Colorado's forests are concentrated in older age classes, with virtually no significant forest in the zero to 20-year age classes.
Forests and woodlands cover 24.4* million acres in Colorado. Within these forested landscapes are several different tree species, the majority of which are coniferous or cone-bearing trees rather than deciduous trees that seasonally shed their leaves. Colorado's primary forest species have been grouped into nine forest types based on the dominant overstory vegetation (Helms 1998)4: aspen, piñon-juniper, spruce-fir, mixed-conifer, oak shrubland, ponderosa pine, lodgepole pine, montane riparian and plains riparian.
Follow the links for brief descriptions of these forest types.
- Lodgepole pine
- Mixed conifer
- Ponderosa pine
- Montane riparian
- Oak shrublands
- Plains riparian
- Plains working forests (agroforestry)
*Acreage numbers have been adjusted due to additional data sources.
Decisions regarding the management, use and condition of Colorado's forests are complicated by a mosaic of public and private ownerships ranging in size from a single acre to several million acres. Each entity brings with it a unique set of philosophies, directives and regulations that further influence the decisions made about their particular part of the forest, as well as the options available to surrounding landowners.
Nearly 68 percent of Colorado's forests are in federal ownership; the primary land manager is the U.S. Forest Service with 47 percent or 11.3 million acres. Nearly three-quarters of the state's high-elevation species such as spruce-fir, lodgepole pine and aspen are located on USFS lands. The Bureau of Land Management oversees an additional 17 percent or 4.2 million acres, primarily in the state's lower elevation piñon-juniper and oak shrubland forests. The National Park Service has responsibility for 380,925 acres or 2 percent of Colorado's forests; the majority of these lands are within the borders of Rocky Mountain National Park.
(USFS=U.S. Forest Service, BLM=Bureau of Land Management, NPS=National Park Service, USFWS=U.S. Fish and Wildlife Service, DOD=Department of Defense)
Despite this significant federal presence, private landowners also play an important role in the stewardship of Colorado's forest resources. Approximately 186,000 private landowners control 30 percent or 7.1 million acres of the state's forested landscapes. Although the majority of these lands are in lower elevations, private landowners are represented in all of Colorado's forest types, including a notable portion of aspen and mixed-conifer forests.
The remainder of Colorado's forests is held by a combination of tribal governments, municipalities, state agencies and other non-federal entities. The Colorado State Land Board, for example, owns approximately 370,000 acres of forest land throughout the state; the largest parcel is the Colorado State Forest near Walden. Two resident tribes, the Ute Mountain Utes and Southern Utes, make their home in southwest Colorado where they own a total of 402,303 acres of forestland. The vast majority of these acres are in ponderosa pine and piñon-juniper forests. These tribes also retain specific hunting rights and other aboriginal rights on national forests throughout their traditional territory, which includes portions of Utah, New Mexico and Colorado. More than a dozen other tribes located outside Colorado also maintain tribal interests and inherent aboriginal rights in Colorado's national forests (USFS 2008)5.
Historically, human use of the forest has been constant, ranging from subsistence gathering to harvesting for mining and railroad industries, and management for wildlife habitat, drinking water and recreation. Growing populations, urban development and climate change pose new and demanding challenges for today's forest managers.
1Shinneman, D., McClellan, R., and Smith, R. 2000. The state of the southern rockies ecoregion: A report by the southern rockies ecosystem project. Golden, CO: Colorado Mountain Club Press. Available online at http://www.restoretherockies.org/report.html.
3Rogers, P., Atkins, D., Frank, M., and Parker, D. 2001. Forest health monitoring in the Interior West. Gen. Tech. Rep. RMRS-GTR-75. Fort Collins, CO: U.S. Forest Service, Rocky Mountain Research Station.
5United States Department of Agriculture, Forest Service (USFS). 2008. Rulemaking for Colorado roadless areas: draft environmental impact statement. Denver, CO: U.S. Department of Agriculture, Forest Service.