Climate Change & Forestry
Common Tree Species
The Montana state tree is the Ponderosa Pine (pinus ponderosae). It is an appropriate and conspicuous choice since it grows in most areas of the state with mature trees growing upward to 180 feet, often in widely scattered stands. Ponderosas are cone-bearing evergreens with distinctive long needles – up to seven inches – usually clustered in tufts of three. Mature trees have very thick, deeply embossed bark that resembles a jig-saw puzzle. Mature trees are long-lived and can survive wildfires. The tree is straight-grained and valuable for sawmill lumber.
The Rocky Mountain Juniper (juniperus scopulorum) is perhaps Montana’s most widespread evergreen. It is found along the benchlands and lower elevations of the western mountains as well as throughout the plains. Commonly called cedar, a Juniper tree can grow as little more than a shrub. Indeed, several related ground varieties are also found throughout the state. But trees up to 50-feet are not uncommon. Many of the state’s fenceposts are cut from Juniper, owing to rot-resistant oils in the wood. The tree offers important habitat for a wide variety of birds and other wildlife.
Although not considered a true fir, the Douglas-fir (Pseudotsuga menziesii) is one of Montana’s most important tree species. It is an interior variety of the giant trees found along the Pacific Coast and is found principally on the eastern and southern aspects of Montana’s mountain ranges. Its wood is dense and durable and is used for a variety of lumber and plywood products. Douglas-fir is the predominant commercial forest tree, occupying about 6.5 million acres in Montana. It is also a popular choice for Christmas trees.
The Lodgepole (pinus contorta) is perhaps Montana’s most common forest tree. The Lodgepole covers almost all suitable mid-elevation habitats of Montana’s mountain ranges. This tall, slender, fast-growing conifer can attain heights in excess of 100 feet and tends to mature into extensive stands with little understory. It is an important source for stud-grade lumber and posts and poles. The bark is flaky, slate-gray and thin. Lodgepole has evolved naturally with fire and actually propagates effectively by releasing seed during fire events. In recent decades, Montana’s Lodgepole forests have been significantly affected by pine bark beetle infestations and forest fire events that may be associated with climate change.
Whitebark Pine (pinus albicaulis) is a slow-growing, long-lived tree of high elevations. In some settings, Whitebark Pine defines the tree-line of Montana mountain ranges. Whitebark is of no commercial value and grows naturally into gnarly, twisted forms. The seed cones produce an important seasonal food source for a variety of wildlife, however, including grizzly bears. Researchers are concerned over pine bark beetle infestations in Whitebark Pine stands in recent years. The tree had previously been regarded as naturally insulated from pine bark beetle attacks due to its high elevation and cold-weather natural environment.
Western Larch (laryx occidentalis) is commonly called Tamarack in western Montana where it occurs exclusively west of the Continental Divide. Although cone-bearing, it is readily identifiable because its needles turn yellow in the fall and are shed. The tree is tall (up to 200 feet) with a typically straight trunk and can live up to 800 years in optimal habitat. Because the tree sheds lower branches as it matures and features heavy bark, it is not usually killed by wildfire. Its wood is strong and commercial value is fairly high.
The Western White Pine (pinus monticola) is a large, straight tree of the lower elevations of northwestern Montana. The tree can attain heights exceeding 200 feet. Its soft wood is light, straight-grained and of high commercial value. The tree is susceptible to an introduced form of blister rust fungus.
Engelmann Spruce (picea englemannia) is a common evergreen of cool mountain creek bottoms, canyons, and lake sides. Its thick lower branches tend to droop and form a cave-like shelter around the trunk. Upper branches whirl toward a tapered top. The wood is of good commercial value, but the riparian location of most stands limits harvest opportunities. The tree is the natural host for the spruce bud worm and moth.
Among the broad leafed deciduous trees, the Black Cottonwood (populus trichocarpa) rates as one of Montana’s native giants. This poplar variety grows to 120 feet and can live up to 300 years. It is found along creek and river bottoms of western and central Montana plains and valleys and is a stalwart of the region’s “riparian forest.” Mature tree tops often take on a flattened appearance with lower branches shed. In early spring, the leaf buds are covered by a fragrant resin. In early summer, the trees release “cotton” seeds that resemble snowflakes in the breeze. The mature bark is heavy and deeply furrowed. The tree is known to regenerate from cut stumps and, under certain circumstances, from buried branch fragments. The tree was essential to the Lewis & Clark Expedition and the Native Americans before them, providing a source for dugout canoes among other uses. The Black Cottonwood, and its relative the Plains Cottonwood (populus deltoides), is important to bottomland stability, wildlife habitat, and as a community shade tree.
Perhaps Montana’s best known deciduous tree is the Quaking Aspen (populus tremuloides). The tree is named for its characteristic trembling in even the slightest breeze. The leaves are oval-shaped and the bark is smooth and varies in color from nearly white to olive green. Heights in Montana rarely exceed 70 feet. Quaking Aspen is found throughout Montana in appropriately cool, moist soils. Aspen possibly possesses the most extensive native range of any tree in North America, extending from Alaska to Mexico and throughout Canada from coast to coast. Quaking Aspen can form large clonal colonies with identical characteristics, propagating from common rootstock. The tree is notable for its vivid bright yellow or orange fall colors. Dieback of Quaking Aspen has been noted throughout the West since about 1996, although the reasons remain unclear.
A survey of Montana trees and shrubs would not be complete without mention of Chokecherry (prunus virginiana). More often a shrub than a tree, Chokecherry can attain heights of about 30 feet. It is found literally everywhere in the state. Its white spring blossoms and late summer fruit are seasonal harbingers. Its common name probably is derived from the bitter taste of unsweetened berries. It is an important component of wildlife habitat for big game as well as for birds.
Box Elder (acer negundo) is a small tree native to eastern Montana and is found along watercourses. The Box Elder is of the Maple family of trees and typically features several asymmetrical trunks. The Box Elder stabilizes stream banks and offers wildlife habitat.