Colorado has a diversity of ecosystem types, each of which may be broken down into many finer categories. Shown in this display are a number of the major ecosystem types on the East Slope of the Colorado Rocky Mountains, along with a few of their representative plant species. In future displays, ecosystems of the West Slope will be featured.
Colorado owes its large ecosystem variety to the environmental diversity throughout the state. Differences in the environment are primarily due to the effects of the Rocky Mountains, which divide the state in half. Mountains cause a number of climatic changes. For example, as warm air rises while traversing the mountains from the west, it is cooled. Cooler air has less capacity to hold water, which causes high precipitation on the West Slope of the mountains. As this air sweeps down the eastern slope, little additional moisture can be wrung from the atmosphere, creating a
Arain shadow@ of low precipitation on the East Slope. This rain shadow extends throughout the eastern plains of Colorado, and is largely responsible for the semi-arid climate that characterizes the region.
Although changes in precipitation may be the most profound of the climatic effects wrought by the mountains, climate is affected in other ways as well. From the eastern plains up into the mountains, precipitation generally increases, and the average temperature decreases. The increased moisture allows the growth of open woodland vegetation in the montane zone, and then higher, dense forest vegetation in the subalpine. Near 11,500 feet, temperatures become so cold and the growing season so short that timberline is reached. Above this somewhat variable boundary, tree growth is precluded.
Important changes in soils are also seen along the gradient from the eastern plains to the alpine. On the plains, soils are well developed, fine textured and alkaline. The regional climate coupled with the calcareous nature of the soils often creates a hardpan, known as caleche, a foot or more below the surface. As one travels up the mountains, soils become poorer in nutrients and much more acidic due to the granitic parent material and the acidic leaf litter that continually falls to the soils from the evergreen trees. These changes in soil profoundly affect the types of plants which can grow in the area.
These examples of environmental diversity, in part, allow the growth of about 3,500 vascular plant species throughout Colorado. We at the Colorado State University Herbarium hope that this display helps you to appreciate some of the beauty and diversity of Colorado
=s native flora.
THE ALPINE ZONE
SHORTGRASS STEPPE
THE SUBALPINE ZONE
MONTANE ZONE
FOOTHILLS ZONE
Wandering through alpine shrub lands on Guanella Pass. Photo by M. Tracey.
Cushion plants amongst the boulders in the alpine on Mount Evans. Yellow flowered plants are Aalpine avens@ (Geum rossii), the purple flowered plants are Asky pilot@ (Polemonium viscosum). Photo by C. Simmons.
A succulent cushion plant, Aalpine spring beauty@ (Claytonia megarhiza). Photo by C. Simmons.
Contorted Abristlecone@ pines (Pinus aristata) on Mount Evans. Photo by C. Simmons.
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Hall=s beard tongue@ (Penstemon hallii) and Ayellow stonecrop@ (Sedum lanceolatum) taking advantage of a crack in the bedrock for a site to grow. Photo by C. Simmons.
The dwarf
Awhip root clover@ (Trifolium dasyphyllum) is a common site in the Mount Evans tundra. Photo by C. Simmons.
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Sky pilot@ (Polemonium viscosum) grows in stable areas in the alpine tundra. Photo by C. Simmons.
The striking
Ashooting star@ (Dodecatheon pulchellum) is a common site in moist subalpine meadows. Photo by C. Simmons.
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Parry=s primrose@ (Primula parryi) is found along streambanks and snowmelt seeps in the subalpine. Photo by C. Simmons.
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Elephantella@ (Pedicularis groenlandica) is a common species in subalpine wetlands. Photo by M. Tracey.
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Sand lily@ (Leucocrinum montanum) is one of the first plants to bloom in the spring on Colorado=s plains and foothills. Photo by S. Spackman.
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Sundew@ (Drosera rotundifolia) is a carnivorous plant that is extremely rare in Colorado. It is found only in acid Abogs@. Photo by B. Neely.
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Marsh marigold@ (Caltha leptosepala) is a common plant found in subalpine wetlands. Photo by C. Simmons.
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Colorado columbine@ (Aquilegia coerulea) is the Colorado state flower. Found in moist subalpine forests. Photo by anonymous.
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Globe flower@ (Anenome multifida) is a common species of moist, open forests. Photo by C. Simmons.
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Scarlet paintbrush@ (Castilleja miniata), what look like the petals of this plant are actually colored leaves. Photo by C. Simmons.
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Holly grape@ (Mahonia repens) is found throughout the lower elevation forests. Photo by S. Spackman.
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Purple fringe@ (Phacelia sericea) grows on gravelly slopes in the subalpine zone. Photo by C. Simmons.
Several species of barrel cacti inhabit the plains and foothills of Colorado. Photo by anonymous.
This species of
Abee plant@ (Cleome multicaulis) is rare in Colorado, restricted to wetlands in the San Luis Valley. Photo by S. O=Kane.
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Stone crop@ (Sedum lanceolatum) is found from the foothills to the alpine. Photo by C. Simmons.
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Pasque flower@ (Pusatilla patens) blooms early in the foothills to the alpine. Photo by S. Spackman.
Tetraneuris acaulis is found on out wash mesas on the plains. Photo by C. Simmons.
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Copper mallow@ (Sphaeralcea coccinea) is common on the plains. Photo by S. Spackman.
Yucca (Yucca glauca) is can be seen producing a spectacular flowering scape during the spring on the plains up to the montane. Photo by B. Johnson.
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Fairy slipper@ (Calypso bulbosa), a beautiful but rare orchid, is found in moist subalpine forests. Photo by C. Simmons.
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Easter daisy@ (Townsendia hookeri) is found on the eastern plains. Photo by N. McIntyre.
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Nuttall=s violet@ (Viola nuttallii) is a pretty yellow violet found in the foothills. Photo by N. McIntyre.
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Prickly Pear@ (Opuntia polyacantha) is ubiquitous on the plains, foothills, and lower montane. Photo by N. McIntyre.
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Evening primrose@ (Oenothera albicaulis) forms huge patches of flowers on the plains. Photo by N. McIntyre.
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Mountain-mahogany@ (Cercocarpus montanus) and juniper (Juniperus sp.) are the dominant species in many foothills scrublands. Photo by T. Gerhardt.
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Spiderwort@ (Tradescantia occidentalis) is found on the plains and foothills. Photo by N. McIntyre.
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Globe flower@ (Anenome multifida) is a common species of moist, open forests. Photo by C. Simmons.
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Scarlet paintbrush@ (Castilleja miniata), what look like the petals of this plant are actually colored leaves. Photo by C. Simmons.
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Parry=s primrose@ (Primula parryi) is found along streambanks and snowmelt seeps in the subalpine. Photo by C. Simmons.
The striking
Ashooting star@ (Dodecatheon pulchellum) is a common site in moist subalpine meadows. Photo by C. Simmons.
The alpine zone in Colorado begins at about 11,400 feet. It is characterized by long, cold winters and a short growing season. Plants need to be specially adapted to grow under these harsh conditions and frequently take on novel growth forms. The contorted growth of Akrumholtz@ species is a striking example of one such adaptation. Low growing, cushion forming plants are another common growth form. Tundra vegetation is frequently dominated by islands of dwarf krumholtz trees, expansive stands of shrubs, and a field layer of grasses, shrubs, and cushion plants.
The subalpine zone is what many people envision when they think of Colorado=s vegetation. This zone starts at about 9,000 feet and covers a vast region in the center of the state. Although it is generally considered a single zone, several community types dominate different areas depending on the specific site environment and successional status. Quaking aspen (Populus tremuloides) stands occur near the lower boundary of the subalpine. They are typically thought of as being early successional, giving rise to spruce-fir forest after about 75 - 100 years. Higher in elevation, lodgepole pine (Pinus contorta) takes the place of aspen as the pioneer tree species. The most common Aclimax@ type of vegetation is the spruce-fir forest (Picea engelmannii - Abies lasiocarpa). This forest type is present at all altitudes in the subalpine and can grow under most environmental conditions in the zone. Although not as common as other vegetation types, subalpine wetlands provide important biodiversity as well as habitat for large mammals such as elk and moose. Also interesting are the broad flat Aparks@, such as South Park and the San Luis Valley, that form between the mountain ranges. These parks frequently have short grass prairie type of vegetation quite different from the surrounding spruce-fir forest.
The montane zone is found between about 6000 and 9000, feet and is frequently divided into an upper and lower zone. Most characteristic of this zone are the open canopy ponderosa pine woodlands (see photo). Fire is important in these areas to maintain the open canopy and grassy understory. On some sites, ponderosa pine co-dominates with douglas fir. In these areas, a closed canopy forest is generally formed. Higher in the montane zone douglas fir becomes the more dominant species. In this region, quaking aspen is commonly the first species to inhabit sites, although sometimes stands of lodgepole pine colonize freshly burnt or otherwise disturbed places. These species generally give way to later successional tree species, however, sometimes they may form persistent stands.
The foothills zone is familiar to anyone living along the Front Range of Colorado. This zone is generally dominated by shrubs such as mountain mahogany, skunk brush, and wild plum, although species composition is highly diverse. In the north to central portions of the state, the species mentioned above generally dominate. Further south, juniper becomes more common. The increase in juniper in the south is frequently accompanied by an increase in pines. This vegetation type is commonly called pinon-juniper woodland. Great expanses of this vegetation type are found throughout southern Colorado, and not just in foothills regions. High in the foothills region, forest vegetation becomes more important and ponderosa pine becomes more common.
The short grass prairie or Asteppe@ is found throughout the eastern third of the state, and is sometimes found in the montane and subalpine zones as well. It is characterized by short, relatively sparse vegetation cover. Grasses are the most common plant life-form found in the prairie, although plants such as sagebrush, rabbit brush, and cacti are also common. This is the zone in which blue gramma grass, Colorado=s state grass, grows. This grass is found throughout the plains and is easily recognizable by it curled and Aflagged@ seed head. CSU is world renown for its research on the short grass steppe and a long-term study area is located on the plains east of Fort Collins in the Pawnee National Grassland. Although often overlooked by residents and visitors in favor of the nearby mountains, the grasslands nevertheless form a beautiful and striking landscape that should not be ignored.