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Level III Ecoregions of Montana

(Revised April 2000)
National Health and Environmental Effects Research Laboratory
U.S. Environmental Protection Agency

The concept of ecoregions was developed to serve as a spatial framework for the research, assessment, management, and monitoring of ecosystems and ecosystem components. Ecoregions are directly applicable to the immediate needs of state agencies, including the development of biological criteria and water quality standards, and the establishment of management goals for nonpoint-source pollution. They are also relevant to integrated ecosystem management, an ultimate goal of most federal and state resource management agencies.

A Roman numeral hierarchical scheme has been adopted for different levels of ecological regions. Level I and Level II divide the North American continent into 15 and 51 regions, respectively. At Level III, the continental United States contains 98 regions (United States Environmental Protection Agency [USEPA], 1996). Level IV regions are more detailed ecoregions for state-level applications; and Level V are the most detailed ecoregions for landscape-level or local level projects. However, depending on the objectives of a particular project, ecoregions may be aggregated within levels of the hierarchy for data analysis and interpretation. Explanations of the methods used to define the USEPA's ecoregions are given in Omernik (1995), Griffith and others (1994), Gallant and others (1989), and Bryce and Clarke (1996).

The concept of an ecoregion framework is an interagency effort to develop a common framework of ecological regions for the entire nation. Reaching that objective requires recognition of the differences in the conceptual approaches and mapping methodologies that have been used to develop the most commonly used existing ecoregion-type frameworks, including those developed by the USFS (Bailey and others, 1994), the USEPA (Omernik, 1987, 1995), and the NRCS (United States Department of Agriculture - Soil Conservation Service, 1981). As each of these frameworks is further developed, the differences between them lessen. Regional collaborative projects, where agreement can be reached among multiple resource management agencies, is a step in the direction of attaining commonality and consistency in ecoregion frameworks for the entire nation.

In Montana, there are seven Level III Ecoregions, not to mention a network of streams, rivers, ponds and lakes. The following map illustrates these Ecoregions. We invite you to learn more about Montana’s Ecoregions, and the fauna they support, by reading the Species Identifications pages located under Species ID.


 
 
 
 

 

#15. NORTHERN ROCKIES

The Northern Rockies is an ecoregion of high, rugged mountains. Although alpine characteristics, including numerous glacial lakes, are found in the higher elevations, the region is not as high nor as snow and ice covered as the Canadian Rockies. The mosaic of vegetation that presently and originally covered the region is different than that of the Middle Rockies. Although Douglas fir, subalpine fir, Englemann spruce, and ponderosa pine are characteristic of both regions, western white pine, western red cedar, and grand fir were and are common in the Northern Rockies, but not the Middle Rockies. Mining activities have caused stream water quality problems in portions of the region.

 
 

#16. MONTANA VALLEY and FOOTHILL PRAIRIES

The Montana Valley and Foothill Prairies is a region characterized by shortgrass prairie. However, it is unlike other grassland-type ecoregions in the Great Plains because of the close proximity to nearby high-forested mountains, which feed the region with many perennial streams and result in a different mosaic of terrestrial and aquatic fauna. Most of the region is farmed and many parts of the valleys have been irrigated. Grazing of beef cattle and sheep is prevalent in the region, even in the forested parts of the foothills.

 

 

#17. MIDDLE ROCKIES

Like the Northern Rockies, this region is composed of steep-crested high mountains that are largely covered by coniferous forests. However, the mix of tree species is somewhat different in the two regions. Lodgepole pine is more common in the Middle Rockies, and white pine, grand fir, and cedar, which are prevalent in the Northern Rockies, are not in this region. Soils in the region are mainly Alfisols, whereas Inceptisols are the major soil order in the Northern Rockies. Also, a greater portion of the Middle Rockies is used for summer grazing of livestock. Recreation and lumbering are major land use activities.

 
 

#18. WYOMING BASIN

This ecoregion is a broad intermontane basin dominated by arid grasslands and shrublands and interrupted by high hills and low mountains. Nearly surrounded by forest covered mountains, the region is somewhat drier than the Northwestern Great Plains to the northeast and does not have the extensive cover of pinyon-juniper woodland found in the Colorado Plateaus to the south. Much of the region is used for livestock grazing, although many areas lack sufficient vegetation to support this activity. The region contains major producing natural gas and petroleum fields.

 
 

#41. Canadian Rockies

As its name indicates, most of this region is located in Canada. It straddles the border between Alberta and British Columbia in Canada and extends southeastward into northwestern Montana. The region is generally higher and more ice-covered than the Northern Rockies. Vegetation is mostly Douglas fir, spruce, and lodgepole pine at lower elevations and alpine fir at middle elevations. The higher elevations are treeless alpine. A large part of the region is in national parks where tourism is the major land use. Forestry and mining occur on the nonpark lands.

 
 

#42. NORTHWESTERN GLACIATED PLAINS

The Northwestern Glaciated Plains ecoregion is a transitional region between the generally more level, moister, more agricultural Northern Glaciated Plains to the east and the generally more irregular, dryer, Northwestern Great Plains to the west and southwest. The western and southwestern boundary roughly coincides with the limits of continental glaciation. Pocking this ecoregion is a moderately high concentration of semi-permanent and seasonal wetlands, locally referred to a Prairie Potholes.
 

#43. NORTHWESTERN GREAT PLAINS

The Northwestern Great Plains ecoregion encompasses the Missouri Plateau section of the Great Plains. It is a semiarid rolling plain of shale and sandstone punctuated by occasional buttes. Native grasslands, largely replaced on level ground by spring wheat and alfalfa, persist in rangeland areas on broken topography. Agriculture is restricted by the erratic precipitation and limited opportunities for irrigation.