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CEGL001780 Muhlenbergia filiculmis Grassland
Type Concept Sentence: No Data Available
Common (Translated Scientific) Name: Slim-stem Muhly Grassland
Colloquial Name: No Data Available
Hierarchy Level: Association
Type Concept: This association occurs in Colorado on xeric grassland sites of higher elevations (2700-3085 m [8860-10,120 feet]) in areas of scant rainfall. In the San Juan Mountains and Rampart ranges, it occurs primarily on volcanically derived soils, and on the Rio Grande it is found on alluvial benches. In the San Juan Mountains, Tertiary volcanic rocks overlying Precambrian crystalline and sedimentary rocks are the predominant parent materials and surface rocks for this association. Fifty percent or more of the ground surface can be exposed rock. The dominant species, Muhlenbergia filiculmis, tends to form rings or cushions averaging 5-20 cm (2-8 inches) or more in diameter. In Florissant National Monument, this grassland is observed to occur in rings or ovals on ridge and hilltops. Bouteloua gracilis is abundant, and several other grasses, including Festuca arizonica and Koeleria macrantha, are found in scattered patches. Commonly associated forbs include Artemisia frigida, Hymenoxys richardsonii, and Arenaria fendleri. Drier sites within the association tend to have an even greater abundance of Muhlenbergia filiculmis than more mesic sites. ~Festuca arizonica - Muhlenbergia filiculmis Grassland (CEGL001605)$$ occurs in the same area but on steeper more south-facing slopes, and has a much higher amount of Festuca arizonica.
Diagnostic Characteristics: No Data Available
Rationale for Nominal Species or Physiognomic Features: No Data Available
Classification Comments: No Data Available
Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: No Data Available
Floristics: This is a grassland association, dominated by a perennial sod grass Muhlenbergia filiculmis, typically short in stature (<0.5 m height). Other associated grasses are primarily perennial bunchgrasses, including Bouteloua gracilis, Festuca arizonica, Koeleria macrantha, Elymus elymoides, and the perennial sedges Carex obtusata and Carex inops ssp. heliophila. Total graminoid cover averages 23%, but can be as high as 40%. Perennial forbs are not typically abundant. Forb species can include Artemisia frigida, Hymenoxys richardsonii, Eriogonum umbellatum, Arenaria fendleri, Geranium caespitosum, Antennaria sp., Cryptantha thyrsiflora, and Castilleja integra. Total forb cover averages 4%. In Florissant National Monument, forb cover was 20-30%. A sparse shrub layer is occasionally present (averaging 4% cover), composed primarily of the evergreen species Ericameria nauseosa (= Chrysothamnus nauseosus) and Ericameria parryi (= Chrysothamnus parryi). Lichens are typically common, with 3% to over 9% (and as high as 65% in Florissant NM) cover of the ground surface.
Dynamics: Wind and fire are likely the driving disturbances maintaining these grasslands. Wind blows away any winter snow accumulation, keeping sites dry. Periodic fires maintain the open structure by killing invading confer seedlings. Hymenoxys richardsonii, Artemisia frigida, and Lappula occidentalis are known to increase in abundance in this grassland while Muhlenbergia filiculmis decreases with persistent overgrazing. High-quality stands will have no to very low cover of these forbs and abundant Muhlenbergia filiculmis. Festuca arizonica appears to do better in more protected or mesic areas.
Environmental Description: Found in a region of high-elevation (>2130 m [7000 feet]), intermountain parks and Front Range foothills, surrounded by montane and subalpine forest slopes. In general, these parks are dominated by grasslands. In Florissant National Monument, it occurs in small patches, roughly circular in shape on hilltops and ellipsoid on ridges. The region has a semi-arid to arid, continental climate. Average annual precipitation is low, <25 cm (10 inches), with a summer peak in July and August. January is the coldest and driest month, and April is the month of greatest snow accumulation. The region is often subjected to strong northerly and westerly winds, which can remove snow cover and subject plants to severe desiccation. This association is found from 2560 to 2930 m (8400-9700 feet) elevation, on slopes with southerly to southwest aspects. Slopes vary from gentle to somewhat steep, and rocks or boulders can be abundant, especially on steeper slopes. Soils are derived from volcanic parent materials, and are dry, well-drained, shallow and coarse-textured (sandy and gravelly). The ground surface is generally bare soil (35-40% cover), with rocks common.
Geographic Range: This association is known only from Mineral, Saguache, and Teller counties, Colorado. It has only been found in the northeastern slopes of the San Juan Mountains, the margins of the San Luis Valley, on the plateaus of the Trickle Mountain area in the Cochetopa Hills, and on dry ridgetops and hilltops in Florissant Fossil Beds National Monument.
Nations: US
States/Provinces: CO, WY
Plot Analysis Summary:
http://vegbank.org/natureserve/ELEMENT_GLOBAL.2.685544
Confidence Level: Moderate
Confidence Level Comments: No Data Available
Grank: G2
Greasons: No Data Available
| Type | Name | Database Code | Classification Code |
|---|---|---|---|
| Class | 2 Shrub & Herb Vegetation Class | C02 | 2 |
| Subclass | 2.B Temperate & Boreal Grassland & Shrubland Subclass | S18 | 2.B |
| Formation | 2.B.2 Temperate Grassland & Shrubland Formation | F012 | 2.B.2 |
| Division | 2.B.2.Nf Western North American Grassland & Shrubland Division | D022 | 2.B.2.Nf |
| Macrogroup | 2.B.2.Nf.3 Tufted Hairgrass - Licorice-root species - Mountain Muhly Subalpine-High Montane Mesic Meadow Macrogroup | M168 | 2.B.2.Nf.3 |
| Group | 2.B.2.Nf.3.a Arizona Fescue - Thurber''s Fescue - Mountain Muhly Grassland Group | G268 | 2.B.2.Nf.3.a |
| Alliance | A3953 Arizona Fescue - Mountain Muhly - Muttongrass Southern Rocky Mountain Montane Grassland Alliance | A3953 | 2.B.2.Nf.3.a |
| Association | CEGL001780 Slim-stem Muhly Grassland | CEGL001780 | 2.B.2.Nf.3.a |
Concept Lineage: No Data Available
Predecessors: No Data Available
Obsolete Names: No Data Available
Obsolete Parents: No Data Available
Synonomy: = Habitat Type 37: Festuca filiculmis, Bouteloua gracilis, Hymenoxys richardsonii, Artemisia frigida (Shepherd 1975)
- Bourgeron, P. S., and L. D. Engelking, editors. 1994. A preliminary vegetation classification of the western United States. Unpublished report. The Nature Conservancy, Western Heritage Task Force, Boulder, CO. 175 pp. plus appendix.
- CNHP [Colorado Natural Heritage Program]. 2006-2017. Tracked natural plant communities. Colorado Natural Heritage Program, Colorado State University, Fort Collins. [https://cnhp.colostate.edu/ourdata/trackinglist/plant_communities/]
- Owns, T., project coordinator, et al. 2004. U.S. Geological Survey and National Park Service Vegetation Mapping Program: Florissant Fossil Beds National Monument. U.S. Geological Survey and National Park Service. 390 pp.
- Ramaley, F. 1942. Vegetation of the San Luis Valley in southern Colorado. University of Colorado Studies, Series D, 1:231-277.
- Shepherd, H. R. 1975. Vegetation of two dissimilar bighorn sheep ranges in Colorado. Colorado Division of Wildlife Report 4. 223 pp.
- Stewart, B. K. 1940. Plant ecology and paleoecology of the Creede Valley, Colorado. Unpublished dissertation, University of Colorado, Boulder. 154 pp.
- WNDD [Wyoming Natural Diversity Database]. No date. Unpublished data on file. Wyoming Natural Diversity Database, University of Wyoming, Laramie, WY.
- Western Ecology Working Group of NatureServe. No date. International Ecological Classification Standard: International Vegetation Classification. Terrestrial Vegetation. NatureServe, Boulder, CO.