Trees

In the Central Rocky Mountains, trees grow between 5500 ft.-11500 ft. (1650 m.-3450 m.). At higher elevations, trees are excluded by cold temperatures. At lower elevations, dry conditions prohibit tree growth. Different tree species dominate areas depending on elevation, precipitation, and aspect (the steepness and direction of the slope the tree is growing on). Only evergreen trees and a few, hearty deciduous trees thrive in the harsh mountain environment.

The Montane forest ecosystem, 5500 ft.-9000 ft. (1650 m.-2700 m.), consists of ponderosa pine forests on warm, south-facing slopes, and Douglas-fir forests on cooler, north-facing slopes. Aspen are also common, indicating areas of past disturbances from fire, windthrow, flooding, or logging. Lodgepole pines are found in areas of disturbance, particularly from fire, and where the soil has fewer nutrients.

Subalpine forests, 9000 ft. to 11500 ft. (2700 m.-3450 m.), are dense, moist communities composed of spire-like Engelmann spruce and subalpine fir. Lodgepole pine and aspen may be found in the lower subalpine zone, and limber pine are often present throughout. At treeline, the forest consists of spruce and firs that become wind-sculptured tree islands called krummholz.

Riparian ecosystems appear as narrow bands of distinctive vegetation along ponds and streams. Blue spruce, aspen, narrowleaf cottonwoods, and shrubs dominate these areas. What follows is a list of the commonly found trees in the park and identification information.

Common Name	Ponderosa Pine
Scientific Name	Pinus ponderosa
Habitat	Montane, 5600 ft.-9500 ft., (1680 m.-2850 m.)
Characteristics For a drawing of a ponderosa pine branch and pine cones, click here.	Mature trees large, with open rounded or flat-topped crown. Height to 100 ft., trunk massive, to 3 ft. diameter. Bark thick, reddish, with vanilla, or butterscotch scent. Needles 3 in. to 7 in. long, in bundles of 2 to 3. Female cones large, woody, with a short spine on each scale. Trees scattered or in clumps, generally uncrowded. Diverse understory, dominated by shrubs and grasses.

Common Name	Douglas Fir
Scientific Name	Pseudotsuga menziesii
Habitat	Montane, 5500 ft.-9500 ft., (1650 m.-2850 m.)
Characteristics For a drawing of a Douglas fir branch and pine cone, click here.	Straight Christmas-tree shape with relatively dense foliage in crown. Height to approximately 100 ft., trunk diameter to 30 inches. Needles 1 in. long, flat, with a rounded tip and a short stalk attaching them to the twig. Female cones 2 in. to 3 in. long, with prominent three-pronged papery bracts protruding from between the cone scales. Relatively dense stands. Sparse understory.

Common Name	Lodgepole Pine
Scientific Name	Pinus contorta
Habitat	Montane and Subalpine, 7800 ft.-11500 ft., (2340 m.-3450 m.)
Characteristics For a drawing of a lodgepole pine branch and cone, click here.	Trees in dense stands are tall and straight, with narrow crowns; in open sites, their crown is broader, resembling ponderosa. Height to approximately 90 ft., trunk diameter to 18 inches. Needles 1 in. to 2 in. long in bundles of two; more of a yellow-green color than those of other conifers. Female cones up to 2 in. long, many remaining closed and attached to the tree for many years. Stands often appearing even-aged, with most of the trees about the same size. Usually sparse understory. Trees in younger stands often nearly all lodgepole; older stands invaded by shade-tolerant spruce, subalpine fir, or Douglas fir.

Common Name	Rocky Mountain Juniper or Red Cedar
Scientific Name	Juniperus scopulorum
Habitat	Montane, 5000 ft.-8000 ft., (1500 m.-2400 m.)
Characteristics For a drawing of a Rocky Mountain Juniper branch, click here.	Shaped like pyramids with an irregular to slightly rounded crown. Height to approximately 16 ft. to 49 ft., trunk diameter up to 3.3 ft. Leaves small, scale-like occurring in pairs, pale-green to grayish- green. Cones appear as berry-like seeds, green or purple containing 1 to 3, usually 2 seeds. Bark is thin, reddish-brown to grayish, and scaly. Grows in rock areas, ridges, cliffs, and hillsides.

Common Name	Quaking Aspen
Scientific Name	Populus tremuloides
Habitat	Montane, Subalpine, and Riparian, 6000 ft.-10000 ft., (1800 m.-3000 m.)
Characteristics For a drawing of a branch of quaking aspen, click here.	Often grow in clumps or groves. Height 39 ft. to 100 ft., diameter to 23 in. or more. Broad, oval leaves with thin, flattened stem. Smooth, light-colored bark ranging from bone white to tan or greenish. Lush green understory compared to conifer forests. Older groves usually invaded by young conifers. The only common deciduous tree growing on mountain slopes away from riparian zones.

Common Name	Narrowleaf Cottonwood
Scientific Name	Populus angustifolia
Habitat	Montane and Riparian, 7000 ft.-9500 ft., (2100 m.-2850 m.)
Characteristics For a drawing of a branch of narrowleaf cottonwood, click here.	Vertical growth habit. Height 40 ft. to 50 ft. at maturity. Older bark gray and fissured. Buds are elongated, pointed, and resinous. Narrow, alternate, simple, 3 in. to 4 in. leaves. Light to medium green during the growing season; yellow in the fall. Catkins appear before the leaves in April. Prefers moist sites and riparian areas.

Common Name	Colorado Blue Spruce
Scientific Name	Picea pungens
Habitat	Montane and Riparian, 7000 ft.-9500 ft., (2100 m.-2850 m.)
Characteristics For a drawing of a Colorado blue spruce branch and cone, click here.	Narrow, pyramidal and an open to dense, irregularly cone-shaped crown. Possible silver-blue color or green. Height from 65 ft. to 115 ft., trunk diameter 32 in. Needles rigid, sharp to the touch almost spine-tipped. Cones over 2.4 in. long; bluish color not obvious. Bark is gray and scaly. Occurs in small groves along streams and occasionally in mixed forests.

Common Name	Engelmann Spruce
Scientific Name	Picea engelmannii
Habitat	Subalpine, 9000 ft.-11500 ft., (2700 m.-3450 m.)
Characteristics For a drawing of an Englemann spruce branch and cones, click here.	Straight trunk and dense crown having a narrow conical shape. Height to approximately 100 ft., trunk diameter to 30 in. Needles attached singly to twig, 1 in. long, 4 sided, with sharp tip. Bark in plate-like layers, relatively thin, reddish on protected side of tree, otherwise gray. Female cones 1 in. to 2 in. long with very papery scales, tan to reddish, mostly clustered in upper third of tree. Thick forest of tall trees with narrow crowns and a dark green color. Upper forest margins ragged and fragmented into wind-sculpted tree islands. Dense understory with immature spruces and firs usually abundant.

Common Name	Subalpine Fir
Scientific Name	Abies lasiocarpa
Habitat	Subalpine, 9000 ft.-12000 ft., (2700 m.-3600 m.)
Characteristics For a drawing of a subalpine fir branch and cones, click here.	Crown often narrower, more spine-like than Engelmann spruce; foliage extremely dense. Height to approximately 80 ft., trunk diameter to 28 in. Needles attached singly to twig, flat, with rounded tips and soft to the touch; often arc upward so that the tips point skyward. Bark typically thin, smooth, and silvery, with horizontal markings; shallow, vertical furrows common on older bark.

Common Name	Limber Pine
Scientific Name	Pinus flexilis
Habitat	Subalpine, 7000 ft.-11000 ft., (2340 m.-3450 m.)
Characteristics For a drawing of a limber pine branch and cones, click here.	Gnarled and twisted in windy sites; in more protected areas, crown broad, symmetrical and often flat-topped. Typically a small tree, 15 ft. to 30 ft. tall, with a trunk diameter to 18 in.; trees frequently with multiple trunks. Older bark gray and platelike; thin and smooth on younger branches, often with pinkish color at windy sites. Needles 1 in. to 2 in. long in bundles of four or five. Female cones large, often several inches long with thick, woody scales; cones bear seeds approximately 3/8 in. long in fall.

Several other non-evergreen species are found in shrub or small tree form along streams and moist hillsides. The more common ones are:

Balsam Poplar (Populus balsamifera)
Thinleaf Alder (Alnus Tenuifolia)
Willow (Salix amygdaloides)
Rocky Mountain Maple (Acer glabrum)

Sources: John Emerick's "Rocky Mountain National Park: Natural History Book", 1995, Roberts Rinehart Publishers, Niwot, CO. John Emerick's "From Grasslands to Glacier", 1992, Johnson Printing, Boulder, CO. Jack L. Carter's "Trees and Shrubs of Colorado", 1988, Jonhson Books, Boulder, CO. Thomas S. Elias's "Trees of North America",1987, Gramercy Publishing Company, New York, NY. Ruth Ashton Nelson's "Rocky Mountain Plants", 1992, Roberts Rinehart Publishers, Niwot, CO.