© Mike Norton (Colorado)

Spruce-Fir Forests

Some 5% of Colorado’s landscape is occupied by this forest type, which is one of the few Colorado forest types that is not fire-adapted.  The typical fire return frequency is around 400 years!  High snowfall and frequent summer showers are the norm, so this is one area of Colorado where drought is atypical.  That being said, droughts can and do happen in this system, and when they do occur, the stressed trees become susceptible to spruce-bud worm outbreaks.  This native invertebrate can kill entire hillsides in one summer.  In the early 20th century, the logging industry and the mining towns took a shine to the timber and much of Colorado’s old-growth spruce fir was cut down.  Much of this system is now re-growth, but is still possible to find old widely-spaced trees with yellow bark and snags and downed trees that create perfect habitat for cavity-nesting birds and pine martens.

Characteristic species include pine marten, lynx, red squirrel, snowshoe hare, boreal owls, elk, grey jay, and Clark’s nutcracker.

Rarity in Spruce-Fir Forests

Boreal toads were once a common species that lived in wetlands situated in high altitude coniferous forests in the Colorado Rockies.  Today less than xx healthy populations exist.  The chytrid fungus is likely responsible for killing most populations.  Lynx and boreal owls spend most of their time in or near large stands of spruce-fir forests.  Although forest habitats (all forests, not just spruce-fir) occupy over 20% of Colorado’s landscape, few rare species are found in these habitats.

Conservation in Spruce-Fir Forests

Most of spruce-fir forests in Colorado are owned and managed by the U.S. Forest Service, with a significant proportion in wilderness status.  In general, spruce-fir forests in Colorado are healthy, intact, and well protected.  Though this ecological system is heavily used for recreation and other human activities, the overall threat status is generally low.  Global climate change may have significant impacts on this system in the future.  For additional information on the status of Colorado's spruce-fir forests, access Colorado's Biodiversity Scorecard here.

Additional Resources

Colorado Natural Heritage Program ecological system description

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NatureServe Explorer ecological systems profiles

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Colorado State Forest Service

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