Black, Justin

Kuhns, Michael R.

McAvoy, Darren

English

DigitalCommons@USU

Utah Forest Types: An Introduction to Utah ForestsDarren McAvoy, Mike Kuhns, Justin BlackRural/Conservation Forestry (Reviewed May 2012)                                                                                                 NR/FF/011IntroductionUtah is known more for its red rock than for its forests, but trees cover about a third of the state. This equals over 15 million acres of scattered forest and woodland found in locations where conditions are just right for trees. About fi ve million of those acres are upland forests of aspen and various conifers. The rest are lower elevation forests in foothills and along stream bottoms and are referred to as woodlands.Forests, Elevation, and AspectElevation and aspect play a signifi cant role in the ecology of Utah forests, mainly through their effect on water availability. Generally, if enough water is available in the soil, trees will be found. The most productive evergreen or coniferous forests grow in upper elevation basins and mountain slopes, and favor northern to eastern aspects. High elevation means more precipitation and cooler temperatures, both good for trees. Lower elevation valley bottoms, on the other hand, have lower precipitation and water is available only near streams, so they tend to have no forests except for cottonwoods and willows near those streams. Mid-elevation foothills get slightly increased precipitation and tend to have woodlands of drought-tolerant trees like pinyons, junipers, oaks, and maples. Often these woodlands are thickest or are only present on more northern and eastern aspects. South and west aspects are the hottest and driest and often won’t have any trees.Other factors that determine where forests and woodlands are found and how well they do include temperature, soil, grazing/browsing, aggressive weeds, and fi re.This fact sheet describes Utah’s forest types – forests categorized by their mix of species and their ecological place in the landscape.Ponderosa pine in Bryce Canyon National ParkForest TypesForest and woodland ecological communities can be better understood by separating them into categories called forest types. Forest types are defi ned by their dominant tree species, each type having its own ecological characteristics that respond to natural and human-caused disturbances in specifi c ways. Utah has about 15 different forest types that include forest species like quaking aspen, Engelmann spruce, Douglas-fi r, lodgepole pine, and ponderosa pine, and woodland species like pinyons, junipers, oaks, and maples.Pinyon-Juniper Type  The forest type with the greatest land area in Utah is pinyon-juniper (PJ), which generally occurs in the foothills. Utah has two kinds of pinyons, singleleaf (Pinus monophylla) and Colorado (P. edulis), and two tree-sized junipers (often called cedars), Utah (Juniperus osteosperma) and Rocky Mountain (J. scopulorum). They often grow together, but they also grow with other tree species like mountain-mahogany (Cercocarpus species), ponderosa pine, white fi r, or Douglas-fi r. PJ density has increased in the past century due to fi re suppression and grazing. These dense stands burn intensely, and some scientists fear that these intense fi res threaten the health and longevity of this forest type.  Aspen Type  Quaking aspen (Populus tremuloides), or quakies, are Utah’s second most common forest type, covering over 1.4 million acres. They are best known for their brilliant yellow to orange fall color, and for being carved on by sheepherders and others. Aspen is found on relatively moist sites. The trees grow together in clones, or groups of stems that share the same root system and genetic makeup. They can be found from canyon bottoms to upper elevation slopes and often grow with conifers like subalpine fi r and spruce. Scientists have shown that there are far fewer aspens in Utah now than in the 1800s, and are concerned that conifers are encroaching upon traditional aspen habitat. The diversity and abundance of forest fl oor plants in an aspen stand can be ten times that found on the fl oor of a stand of evergreen trees.Pinyon-Juniper Type 8 million acres at 5,000 to 8,000 feet elevation. Occupy the driest forested sites. Nearly 60 percent of Utah forest cover. Important for wildlife habitat and livestock grazing. Used for fence posts and poles, fi rewood, mine props, charcoal, Christmas trees, and pinyon nuts. Widely distributed, from mixed stands in southern Utah to pure juniper stands in northern Utah. The Raft River Mountains in northwest Utah are the northern-most range of singleleaf pinyon. High scenic/recreation value in some areas. Pinyon engraver beetle signifi cantly affects both species of pinyon. Aspen Type 1.4 million acres at 7,000 to 10,000 feet elevation. Important for wildlife habitat, grazing, biodiversity, and aesthetics. Easily regenerates after clearcutting or burning by producing numerous root sprouts; rarely reproduces from seed in the West. Root damage during logging can reduce sprouting. Initially out-competes associated conifers after a clearcut or fi re by sprouting from established root system, forming large, genetically identical clones. Shade intolerant and short-lived, so lack of disturbance eventually leads to replacement by more shade tolerant conifers like spruce and fi r; this is common in Utah due to fi re suppression.  Slowly spreads into non-aspen sites by root system outgrowth and sprouting. Replacement of aspen by existing conifers can be encouraged by cutting or girdling aspen while leaving the conifers alone.  Clearcutting a mixed aspen-conifer stand is likely to lead to replacement with pure aspen.Douglas-fi r Type  The next most common forest types are those dominated by Douglas-fi r (Pseudotsuga menziesii) and white fi r (Abies concolor). Douglas-fi r is very common and tends to grow in fairly pure stands, while white fi r is more scattered and less common. These mid-elevation species cover more than one million acres. Early pioneers sought out Douglas-fi r for building material, sometimes calling it red pine because it is an evergreen with reddish heartwood. There are at least fi ve canyons in Utah named Red Pine. One easy identifi er for Douglas-fi r is the mouse-tail bracts that stick out from under the cone scales.Spruce-Fir Type 3/4 million acres at 8,000 to 10,000 feet elevation. Important for wood fi ber, though spruce is worth considerably more than fi r; wildlife habitat, recreation, and watershed values also important.  Highest elevation type; dominated by subalpine fi r, which is very shade tolerant, and Engelmann spruce, which is slightly less tolerant.  Other associated species are lodgepole and limber pine, Douglas-fi r, and aspen.  Regeneration after harvest is diffi cult; group selection and shelterwood methods can be used; protection is needed for seedling survival; planting and protection of advanced regeneration help.  Stands can be very complex in structure and age distribution; group shelterwood can be used in more uneven-aged stands; openings should be less than two times tree height for good protection.  Fires are infrequent but important in dry years; windthrow is an important disturbance factor.  Root disease, bark beetles, and western spruce budworm are signifi cant pests; to control spruce beetle, remove attacked or susceptible trees and treat slash.Douglas-fi r Type    1 million acres at 6,000 to 9,000 feet elevation. Important timber and recreation resource and provides critical wildlife habitat.  Refers to sites where Douglas-fi r could dominate, but other species may be present, including true fi rs, spruces, and lodgepole and ponderosa pines. Intermediate shade tolerance, so undisturbed Douglas-fi r can be replaced by more shade tolerant subalpine fi r or Engelmann spruce; fairly common in Utah due to fi re suppression.  Use group selection or shelterwood for reproduc-tion since most associated species need protection to regenerate naturally or as planted seedlings.  Clearcutting if aspen or lodgepole pine is present will likely regenerate the stand to those species.  Careful overstory removal can encourage natural regeneration where adequate advanced regeneration is present.  Clearcutting or overstory removal without adequate advanced regeneration will convert to shade intolerant species or to a poorly stocked stand of shade tolerant species such as subalpine fi r.  Important pests are western spruce budworm, bark beetles, and dwarf mistletoe; to control and improve stand vigor, increase species and age-class diversity. Spruce-Fir Type  Spruce-fi r is the fourth most common coniferous forest type in Utah, and is generally found at higher elevations.  It occurs as stands of Engelmann spruce (Picea engelmannii) mixed with subalpine fi r (Abies lasiocarpa) and in association with Douglas-fi r, white fi r, and aspen, as well as various pines. The great majority of spruce found in Utah is Engelmann spruce, while about fi ve percent is blue spruce (Picea pungens). Spruce is an important timber species in Utah, valued for its clear, straight grain. Spruce is also used for house logs. A massive spruce beetle epidemic currently is devastating much of Utah’s spruce forest.Pine Types  Several pine forest types exist in Utah, including ponderosa, lodegpole, limber, and bristlecone types. Pines are intolerant of shade and more drought tolerant than many of their associated species.Ponderosa Pine  Ponderosa pine (Pinus ponderosa) is the pine of Bryce Canyon National Park, and is found from the Uintas south. Ponderosa is our largest pine, eventually getting an orange-yellow bark that earns it the name yellow pine, as in Yellow Pine Campground on the Uinta National Forest.Lodgepole Pine  Lodgepole pine (Pinus contorta) covers nearly a half million acres in Utah, mostly at higher elevations in and north of the Uintas. Lodgepole is relatively short-lived (150 years), but it grows straight and tall on good sites. It is used for lodge poles and fence poles, as well as lumber.Limber Pine  Limber pine (Pinus fl exilis) tends to occupy the higher ridges in Utah. Although limber pine occupies less than a million acres in Utah, its common name, “white pine,” honors 19 place names in the state. Bristlecone Pine  Bristlecone pine (Pinus longaeva) occupies a very small range in Utah, mostly on upper elevation plateaus in southern and western Utah. This species is best known for including the oldest living tree, and perhaps the oldest organism, on Earth. Oak-Maple Type  Gambel oak (Quercus gambellii) and canyon or bigtooth maple (Acer grandidentatum) woodlands occupy our lower mountain slopes and foothills, and offer outstanding fall color. As urban development expands and more homes are built in these woodlands, their management is increasingly important to prevent fi re disasters.Oak-Maple Type Common native species on lower elevation foothills in Utah, between 5,000 and 7,800 feet. Important for birds and big game. Although they often grow together, oaks prefer southern aspects while maples prefer northern and eastern aspects. Oak is fi re adapted; it grows back quickly from root sprouts after a fi re kills the tree tops. Oak tend to be scrubby small trees less than 30 feet in height, but can reach 60 feet tall. Maple tends to have several stems and can reach 50 feet in height.Pine Types Total of 1.1 million acres of pines at 7,000 to 10,000 feet elevation, depending on species. Ponderosa pine naturally grows in open, park-like stands maintained by frequent fi re; fi re suppression leads to dense stands; thick bark protects older trunks from fi re damage; commercially valuable. Lodgepole pine tends to grow in pure stands that regenerate quickly after a fi re from seed; some trees have serotinous (closed) cones that open after a fi re to release their seeds; commercially valuable.  Limber pine occupies cold, windy, steep, rocky sites, often near tree line; not commercial; regeneration depends on seed caches made by birds like Clark’s nutcracker; some Utah limber pines are over 2,500 years old.Utah State University is committed to providing an environment free from harassment and other forms of illegal discrimination based on race, color, religion, sex, national origin, age (40 and older), disability, and veteran’s status. USU’s policy also prohibits discrimination on the basis of sexual orientation in employment and academic related practices and decisions. Utah State University employees and students cannot, because of race, color, religion, sex, national origin, age, disability, or veteran’s status, refuse to hire; discharge; promote; demote; terminate; discrimi-nate in compensation; or discriminate regarding terms, privileges, or conditions of employment, against any person otherwise qualifi ed. Employees and students also cannot discriminate in the classroom, residence halls, or in on/off campus, USU-sponsored events and activities. This publication is issued in furtherance of Cooperative Extension work. Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, Jack M. Payne, Vice President and Director, Cooperative Extension Service, Utah State University. Published June 2004.More InfomationFor more information on Utah’s forests and woodlands visit the Utah State University  Forestry Extension Web site at http://extension.usu.edu/forestry.

Utah Forest Types: An Introduction to Utah Forests

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Utah Forest Types: An Introduction to Utah Forests

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