Colorado Statewide Forest Resource Assessment

Spruce-Fir 9Spruce-fi r is among the most extensive forest types in Colorado, coveringapproximately 4.6 million acres or 19 percent of the state’s forested lands. 10Engelmann spruce and subalpine-fi r are the primary species in this foresttype, but aspen and other conifers also may occur. The USFS manages themajority of spruce-fi r forests (88 percent), which generally grow at elevationsfrom 9,000 to 12,000 feet. Unlike many other Colorado forest types, spruce-fi rforests are not adapted to fi re. In the case of a stand-replacing fi re, it maytake as long as 300-400 years for a spruce-fi r forest to regenerate. Threats tospruce-fi r include fi re and native insects such as spruce beetle and westernspruce budworm, particularly in times of drought or when trees are otherwisestressed.Spruce-fi r forests are highly valued for their contributions to water supply,recreation and wood products. The soft wood and uniform color makesspruce ideal for boards, mine props, plywood and musical instruments.Although there are fewer uses for subalpine fi r, it can be made into lumber,produces fi ne Christmas trees and its aromatic resin serves as a basis for“pine-scented” products and adhesives (CSFS 2008). Spruce-fi r forests alsoprovide important habitat to a number of subalpine wildlife species, includingthe red squirrel, snowshoe hare, pine marten, boreal owl, Clark’s nutcrackerand three-toed woodpecker. Spruce-fi r forests are essential to the habitatmatrix required by the endangered Canada lynx, and one of Colorado’s mostat-risk amphibians – the boreal toad – inhabits open and mesic areas withinspruce-fi r forests, including subalpine lakes with marshes and beaver ponds.Seventeen of Colorado’s Species of Greatest Conservation Need, as identifi edby the Colorado Division of Wildlife (CDOW), rely on spruce-fi r forests fortheir primary habitat. The CDOW identifi es habitat shifting and alterationdue to climate change as a signifi cant threat to wildlife that rely on spruce-fi rhabitats. 11AspenAspen is another of Colorado’s extensive forest types, covering 5 million acresor 21 percent of the state’s forested land. 12 The aspen is Colorado’s onlywidespread, native deciduous tree and can be found from 6,900 to 10,500 feetin elevation, particularly on the West Slope. The USFS manages the majorityof Colorado’s aspen forests (62 percent), but a signifi cant portion (27 percent)is in private ownership. While aspen’s thin, living bark makes it prone to a hostof insect pests and diseases, the primary threats to Colorado’s aspen forestsare fi re suppression and chronic animal browsing (especially by elk) of youngaspen shoots (CSFS 2005). A recent wave of aspen die-off (referred to as“sudden aspen decline”) has caused additional concern in some parts of thestate. Scientists suspect drought, warmer temperatures, aspect and elevationare strong factors in this decline, although tree age also is a factor. Researchon this issue is ongoing.9Colorado’s forest types are listed in this section according to the elevation at which they generally occur, beginningwith the highest elevation and proceeding to the lowest.10For more information on spruce-fir and other high-elevation forests in Colorado, see the CSFS 2008 Report: TheHealth of Colorado’s Forests available online at http://csfs.colostate.edu/pages/pub-csfs2.html.11The Species of Greatest Conservation Need referred to throughout this assessment were identified by the ColoradoDivision of Wildlife as part of Colorado’s State Wildlife Action Plan available online at http://wildlife.state.co.us/WildlifeSpecies/ColoradoWildlifeActionPlan/.12For more information on Colorado’s aspen forests, see the CSFS 2005 Report on the Health of Colorado’s Forestsand 2008 Report: The Health of Colorado’s Forests available online at http://csfs.colostate.edu/pages/pub-csfs2.html.8