Mountain Mahogany Woodland and Shrubland
Provisional State Rank
* (see reason below)
State Rank Reason
This system is patchy and not common, but because occurrences are so dispersed, threats are also dispersed.
This ecological system occurs most frequently on moderately steep to very steep slopes in the mountain ranges of southwestern Montana, but extends as far north as the northern foothills of the Elkhorn Range and as far east as the Wolf Mountains on the Crow Indian Reservation. It occurs on rocky outcrops on south and southwestern aspects at 1,060-2,260 meters (3,500-7,400 feet) and forms small- to large-patch stands on dry and rocky soils. In Montana, this shrubland system is dominated by curl-leaf mountain mahogany (Cercocarpus ledifolius). Rocky Mountain juniper (Juniperus scopulorum) occurs throughout this system’s range and Utah juniper (J. osteosperma) occurs in the Pryor Mountains. Conifers such as Douglas-fir (Pseudotsuga menziesii), limber pine (Pinus flexilis) and ponderosa pine (P. ponderosa) may also occur in some stands. Other co-dominant shrubs include mountain big sagebrush (Artemisia tridentata ssp. vaseyana), antelope bitterbrush (Purshia tridentata) and rubber rabbitbrush (Ericameria nauseosa). Other low shrubs such as snakeweed (Gutierrezia sarothrae) and fringed sage (Artemisia frigida) are common. Undergrowth is dominated by bunchgrasses, usually bluebunch wheatgrass (Pseudoroegneria spicata), needle and thread (Hesperostipa comata), Indian ricegrass (Achnatherum hymenoides) or Idaho fescue (Festuca idahoensis). Curl-leaf mountain mahoganyis a slow-growing, drought-tolerant species that generally does not re-sprout after fire. Prolonged drought, potential for increased fire severity and exotic species invasion are changing the dynamics of this system.
Forest and Woodland, vegetation cover greater than 10%, Montane to foothill elevations, Cercocarpus ledifolius
This ecological system occurs most frequently on moderately steep to very steep slopes in the mountain ranges of southwestern Montana, but it extends as far north as the northern foothills of the Elkhorn Range and as far east as the Wolf Mountains on the Crow Indian Reservation. Elsewhere in the western United States, this system occurs in hills and mountain ranges of the Intermountain West basins from the eastern foothills of the Sierra Nevada northeast to the foothills of the Bighorn Mountains.
Ecological System Distribution
Approximately 284 square kilometers are classified as Mountain Mahogany Woodland and Shrubland in the 2017 Montana Land Cover layers.
Grid on map is based on USGS 7.5 minute quadrangle map boundaries.
Montana Counties of Occurrence
Beaverhead, Big Horn, Broadwater, Carbon, Carter, Cascade, Deer Lodge, Gallatin, Granite, Judith Basin, Lewis and Clark, Madison, Meagher, Mineral, Missoula, Park, Powder River, Powell, Ravalli, Rosebud, Sanders, Stillwater, Sweet Grass, Wheatland
Large Patch or Small Patch
This ecological system occurs as small- to large-patch stands on dry and rocky soils associated with moderately steep to very steep slopes, although occurrences on flat to gently sloping surfaces are also found in Montana. It is most prevalent on limestone outcrops where extensive stands develop, although it also occurs on other parent materials, generally as small patches. It can occur on all aspects but is most prevalent on south and southwestern aspects. This system’s observed elevation range within the state is 1,060-2,260 meters (3,500-7,400 feet). Climate within its distribution range in Montana is typical of mid-continental regions with long severe winters and hot, dry summers. This system is important winter range for deer and elk.
This shrubland system is dominated by curl-leaf mountain mahogany (Cercocarpus ledifolius). Rocky Mountain juniper (Juniperus scopulorum) occurs throughout this system’s range and Utah juniper (J. osteosperma) occurs in the Pryor Mountains. Conifers such as Douglas-fir (Pseudotsuga menziesii), limber pine (Pinus flexilis) and ponderosa pine (P. ponderosa) may also occur in some stands. Ponderosa pine stands within this system are mostly found in eastern Montana. Other co-dominant shrubs include mountain big sagebrush (Artemisia tridentata ssp. vaseyana), antelope bitterbrush (Purshia tridentata), and rubber rabbitbrush (Ericameria nauseosa). Other low shrubs such as snakeweed (Gutierrezia sarothrae) and fringed sage (Artemisia frigida) are common. Undergrowth is dominated by bunchgrasses, usually bluebunch wheatgrass (Pseudoroegneria spicata), needle and thread (Hesperostipa comata), and Indian ricegrass (Achnatherum hymenoides).Other low shrubs such as broom snakeweed (Gutierrezia sarothrae) and fringed sage (Artemisia frigida) are common (Mueggler and Stewart, 1980).
Bluebunch wheatgrass (Pseudoroegneria spicata) is the dominant grass throughout this system, although needle and thread (Hesperostipa comata) and Indian ricegrass (Achnatherum hymenoides) may be co-dominant on more xeric occurrences. Mesic occurrences are frequently dominated or co-dominated by Idaho fescue (Festuca idahoensis). Prairie junegrass (Koeleria macrantha) is a minor component. Due to the rocky and shallow substrates, undergrowth cover is relatively sparse, often with less than 20% cover. Common forbs include rosy pussytoes (Antennaria rosea), sulphur buckwheat (Eriogonum umbellatum), few-seed draba (Draba oligosperma), tufted fleabane (Erigeron cespitosus), Hood’s phlox (Phlox hoodii), and stoneseed (Lithospermum ruderale). Cacti such as plains pricklypear (Opuntia polyacantha)and Missouri foxtail cactus (Mammillaria missouriensis) are present on especially xeric sites. Within this system, cheatgrass (Bromus tectorum) or other annual bromes and invasive weeds can be abundant.
National Vegetation Classification Switch to Full NVC View
Adapted from US National Vegetation Classification
A0586 Cercocarpus ledifolius / Shrub Understory Woodland Alliance
A0828 Cercocarpus ledifolius Scrub Alliance
CEGL000967 Cercocarpus ledifolius - Pseudoroegneria spicata Scrub
A3570 Cercocarpus ledifolius / Herbaceous Understory Woodland Alliance
CEGL000962 Cercocarpus ledifolius - Festuca idahoensis Woodland
*Disclaimer: Alliances and Associations have not yet been finalized in the National Vegetation Classification (NVC) standard.
A complete version of the NVC for Montana can be found here
Curl-leaf mountain mahogany is easily killed by fire at all intensities. Some shrubs may re-sprout following low-intensity fires, but these are typically low in vigor and do not persist. Regeneration is by seedling recruitment. Post-fire regeneration is quick unless fire intensity is severe. High-intensity fires kill all standing shrubs and may also eliminate the seed bank (Gucker, 2006). However, a lack of continuous fuels, sparse undergrowth, open stand structure, and low downed wood accumulations contribute to a low fire frequency within this system. Fire return intervals currently range from 70 to 110 years with the majority of fires being mixed severity (U.S. Department of Agriculture, 2012). Prior to 1900, fire return intervals are estimated to have been much shorter, and have increased due to fire suppression and heavy livestock grazing, reducing fine fuel loads (Gucker, 2006). The absence of fire in curl-leaf mountain mahogany habitats in central, southwestern, and southeastern Montana has in some instances increased curl-leaf mountain mahogany abundance and regeneration success (Gruell, 1982).
Curl-leaf mountain mahogany provides food and cover for a variety of wildlife species such as deer and elk. Some livestock (domestic goats, sheep, and cattle) use this system in spring, fall, and/or winter, but rarely in the summer. In other areas of this system’s geographic range, heavy grazing practices have been observed to lead to a decrease in associated grasses and an increase in the spread of cheatgrass (Bromus tectorum) (Young, 1989). Thus, sites invaded by cheatgrass are changing the dynamics of this system by increasing fire potential, severity, and spread.
Excessive grazing can lower the cover of the most common perennial bunchgrasses in this system and lead to an increase in the cover of prairie junegrass and needle and thread grass. Unpalatable shrubs such as fringed sage or snakeweed also increase under heavy grazing pressure. Severe grazing can lead to an abundance of cheatgrass (Bromus tectorum), spotted knapweed (Centaurea maculosa), or other noxious species capable of colonizing dry, rocky soils. Prescribed fire exposes mineral soils which promote seedling establishment and is recommended for stands in which fuel levels are low, and in which cheatgrass is absent. Fire is also recommended for sites in west-central and southwestern Montana to encourage curl-lead mountain mahogany regeneration while slowing succession by shade tolerant Douglas fir (Gucker, 2006).
Restoration strategies will depend on the type and intensity of the disturbance, and in the case of fire, on the degree of fire severity and fire recovery objectives. Light or moderately intensive burns can increase cover of native perennial bunchgrasses during the first two years following fire on sites where there was good pre-fire condition with minimal exotic cover. However, severely burned sites will require replanting with curl-leaf mountain mahogany seedlings and other co-dominant shrubs, due to the slow recovery time within this system and low rates of natural seedling recruitment. When planting from seed, cold, moist stratification is required to enhance germination success (Gucker, 2006). Generally, larger container volume of nursery stock results in higher outplanting success; 20-cubic inch container stock is recommended for use on these sites. Curl-leaf mountain mahogany is rated as good to excellent for soil erosion control due to its ability to stabilize soils. Planting rates must be developed on a site-by-site basis to meet management objectives.
Successful restoration of native grasses within this system may be limited to sites where pre-fire cheatgrass cover was low. Fall germination and rapid elongation of roots provide cheatgrass with a competitive advantage over native perennial species (Harris 1967). Cheatgrass reduces growth of bluebunch wheatgrass seedlings and is capable of producing twice the root quantity during the first 45 days of growth (Aguirre and Johnson 1991). Prolific seed production also contributes to the competitive advantage of this species over native grasses. Thus, on sites that are heavily infested with cheatgrass prior to fire, seeding rates must be adjusted to include more competitive native grass species. Some selections of bluebunch wheatgrass that exhibit desirable growth characteristics may have promise for establishing this species on invaded sites.
Species Associated with this Ecological System
- Details on Creation and Suggested Uses and Limitations
How Associations Were Made
We associated the use and habitat quality (common or occasional) of each of the 82 ecological systems mapped in Montana for
vertebrate animal species that regularly breed, overwinter, or migrate through the state by:
- Using personal observations and reviewing literature that summarize the breeding, overwintering, or migratory habitat requirements of each species (Dobkin 1992, Hart et al. 1998, Hutto and Young 1999, Maxell 2000, Foresman 2012, Adams 2003, and Werner et al. 2004);
- Evaluating structural characteristics and distribution of each ecological system relative to the species' range and habitat requirements;
- Examining the observation records for each species in the state-wide point observation database associated with each ecological system;
- Calculating the percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system to get a measure of "observations versus availability of habitat".
Species that breed in Montana were only evaluated for breeding habitat use, species that only overwinter in Montana were only evaluated for overwintering habitat use, and species that only migrate through Montana were only evaluated for migratory habitat use.
In general, species were listed as associated with an ecological system if structural characteristics of used habitat documented in the literature were present in the ecological system or large numbers of point observations were associated with the ecological system.
However, species were not listed as associated with an ecological system if there was no support in the literature for use of structural characteristics in an ecological system, even if
point observations were associated with that system.
Common versus occasional association with an ecological system was assigned based on the degree to which the structural characteristics of an ecological system matched the preferred structural habitat characteristics for each species as represented in scientific literature.
The percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system was also used to guide assignment of common versus occasional association.
If you have any questions or comments on species associations with ecological systems, please contact the Montana Natural Heritage Program's Senior Zoologist.
Suggested Uses and Limitations
Species associations with ecological systems should be used to generate potential lists of species that may occupy broader landscapes for the purposes of landscape-level planning.
These potential lists of species should not be used in place of documented occurrences of species (this information can be requested at: http://mtnhp.org/requests/default.asp
) or systematic surveys for species and evaluations of habitat at a local site level by trained biologists.
Users of this information should be aware that the land cover data used to generate species associations is based on imagery from the late 1990s and early 2000s and was only intended to be used at broader landscape scales.
Land cover mapping accuracy is particularly problematic when the systems occur as small patches or where the land cover types have been altered over the past decade.
Thus, particular caution should be used when using the associations in assessments of smaller areas (e.g., evaluations of public land survey sections).
Finally, although a species may be associated with a particular ecological system within its known geographic range, portions of that ecological system may occur outside of the species' known geographic range.
- Adams, R.A. 2003. Bats of the Rocky Mountain West; natural history, ecology, and conservation. Boulder, CO: University Press of Colorado. 289 p.
- Dobkin, D. S. 1992. Neotropical migrant land birds in the Northern Rockies and Great Plains. USDA Forest Service, Northern Region. Publication No. R1-93-34. Missoula, MT.
- Foresman, K.R. 2012. Mammals of Montana. Second edition. Mountain Press Publishing, Missoula, Montana. 429 pp.
- Hart, M.M., W.A. Williams, P.C. Thornton, K.P. McLaughlin, C.M. Tobalske, B.A. Maxell, D.P. Hendricks, C.R. Peterson, and R.L. Redmond. 1998. Montana atlas of terrestrial vertebrates. Montana Cooperative Wildlife Research Unit, University of Montana, Missoula, MT. 1302 p.
- Hutto, R.L. and J.S. Young. 1999. Habitat relationships of landbirds in the Northern Region, USDA Forest Service, Rocky Mountain Research Station RMRS-GTR-32. 72 p.
- Maxell, B.A. 2000. Management of Montana's amphibians: a review of factors that may present a risk to population viability and accounts on the identification, distribution, taxonomy, habitat use, natural history, and the status and conservation of individual species. Report to U.S. Forest Service Region 1. Missoula, MT: Wildlife Biology Program, University of Montana. 161 p.
- Werner, J.K., B.A. Maxell, P. Hendricks, and D. Flath. 2004. Amphibians and reptiles of Montana. Missoula, MT: Mountain Press Publishing Company. 262 p.
- Native Species Commonly Associated with this Ecological System
- Native Species Occasionally Associated with this Ecological System
Original Concept Authors
Montana Version Authors
- Classification and Map Identifiers
Cowardin Wetland Classification:
National Land Cover Dataset:
|Element Global ID
||CES304.772, Inter-Mountain Basins Mountain Mahogany Woodland and Shrubland
43: Mixed Forest
4303: Inter-Mountain Basins Mountain Mahogany Woodland and Shrubland
- Literature Cited AboveLegend: View Online Publication
- Gucker, C.L. 2006. Cercocarpus ledifolius. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory.
- U.S. Department of Agriculture, Forest Service, Missoula Fire Sciences Laboratory. 2012. Information from LANDFIRE on Fire Regimes of Mountain-Mahogany Communities. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Serv
- Additional ReferencesLegend: View Online Publication
Do you know of a citation we're missing?
- Aguirre, Lucrecia, and Douglas A. Johnson. 1991. "Influence of Temperature and Cheatgrass Competition on Seedling Development of Two Bunchgrasses". Journal of Range Management. 44 (4): 347-354.
- Gruell GE. 1982. Fires' influence on vegetative succession--wildlife habitat implications and management opportunities. In: Eustace CD, editor. Proceedings: Montana Chapter of the Wildlife Society. Billings, MT: The Wildlife Society; p 43-50.
- Harris, G.A. 1967. Some competitive relationships between Agropyron Spicatum and Bromus tectorum. Ecological Monographs 37:89-111.
- Mueggler, W. F. and W. L. Stewart. 1980. Grassland and shrubland habitat types of western Montana. USDA Forest Service Gen. Tech. Rep. INT-66, Intermountain Forest and Range Exp. Sta., Ogden, Utah. 154 pp.
- Young JA. 1989. Intermountain shrubsteppe plant communities--pristine and grazed. Western raptor management symposium and workshop: Proceedings: 1987 October 26-28; Boise, ID. Scientific Technical Series No. 12. Washington DC: National Wildlife Federation; p 3-14.