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CEGL002240 Sporobolus heterolepis - Achnatherum richardsonii - Danthonia intermedia Grassland
Type Concept Sentence: No Data Available
Common (Translated Scientific) Name: Prairie Dropseed - Richardson''s Needlegrass - Timber Oatgrass Grassland
Colloquial Name: Black Hills Montane Grassland
Hierarchy Level: Association
Type Concept: This montane grassland is best developed on the Limestone Plateau in the high western Black Hills of the United States. The zone of occurrences extends from the northwestern Black Hills in Wyoming, southeast and then south to west of Custer, South Dakota. A few stands occur in the adjacent Central Core on sites underlain by metamorphic rocks. Similar stands have been found at high elevations at two disjunct sites in the northwestern Black Hills: Cement Ridge southeast of Sundance, and Warren Peaks in the southern Bear Lodge Mountains. These sites are underlain by igneous rocks, and the stands differ somewhat in floristic composition. This type occurs at higher elevations, where there usually is significant snow cover from November through April. Most montane grasslands occur above 1800 m (5900 feet). In northeastern Wyoming, montane grasslands are found in drainage bottoms as low as 1556 m (5100 feet). Most montane grasslands occur in the bottoms and on lowermost slopes of broad drainages, on sites ranging from flat to moderately sloping with variable aspect. A few occur on rolling uplands.
Most stands of Black Hills Montane Grassland are graminoid-dominated, but forb-rich. Overall herbaceous cover is in the 60-100% range. The type as currently defined includes several phases. On drier sites, overall cover is typically in the 50-75% range. Dominant graminoids include Sporobolus heterolepis, Achnatherum richardsonii and Danthonia intermedia. Other graminoids commonly present include Elymus trachycaulus ssp. subsecundus and Hesperostipa spartea. On more mesic sites, overall cover is often 100%. Dominant graminoids often include Poa pratensis, Nassella viridula, Achnatherum richardsonii, and Danthonia intermedia. Elymus trachycaulus ssp. subsecundus and Hesperostipa spartea may be present and locally common.
Most stands of Black Hills Montane Grassland are graminoid-dominated, but forb-rich. Overall herbaceous cover is in the 60-100% range. The type as currently defined includes several phases. On drier sites, overall cover is typically in the 50-75% range. Dominant graminoids include Sporobolus heterolepis, Achnatherum richardsonii and Danthonia intermedia. Other graminoids commonly present include Elymus trachycaulus ssp. subsecundus and Hesperostipa spartea. On more mesic sites, overall cover is often 100%. Dominant graminoids often include Poa pratensis, Nassella viridula, Achnatherum richardsonii, and Danthonia intermedia. Elymus trachycaulus ssp. subsecundus and Hesperostipa spartea may be present and locally common.
Diagnostic Characteristics: No Data Available
Rationale for Nominal Species or Physiognomic Features: No Data Available
Classification Comments: This type is equivalent to the mountain meadow stage of McIntosh (1930), a successional stage found on low ground in mountain valleys in the Limestone District (now called the Limestone Plateau). McIntosh recognized two phases: a lower meadow phase with timothy (Phleum pratense) the most abundant grass, and a drier phase found on well-drained slopes with the speargrasses (Stipa spp.) and dropseed (Sporobolus heterolepis) most conspicuous. The association described here is roughly equivalent to the well-drained slope phase of McIntosh, but includes somewhat more mesic stands in drainage bottoms in the drier southern part of its range. McIntosh''s lower meadow phase dominated by timothy is not included within this type; rather it is treated as an exotic timothy grassland type. We have very little evidence as to what the native composition of these stands was prior to timothy introduction.
Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: No Data Available
Floristics: Most stands of this montane grassland type are graminoid-dominated, but forb-rich. Overall herbaceous cover is in the 60-100% range. Even on the driest sites, cover is greater than 50%. The ratio of graminoid cover to forb cover is variable, ranging from 3:1 to 2:1 at most sites surveyed. Several phases can be defined. On the driest sites, such as slopes, ridgecrests, summits and rockier areas in drainage bottoms, overall cover is typically in the 50-75% range. Dominant graminoids include Sporobolus heterolepis, Achnatherum richardsonii (= Stipa richardsonii) and Danthonia intermedia. Other graminoids commonly present include Elymus trachycaulus ssp. subsecundus (= Agropyron subsecundum) and Hesperostipa spartea (= Stipa spartea). On more mesic sites in drainage bottoms, overall cover is often 100%. Dominant graminoids vary, but often include Poa pratensis, Nassella viridula, Achnatherum richardsonii, and Danthonia intermedia. Elymus trachycaulus ssp. subsecundus and Hesperostipa spartea may be present and locally common. Sporobolus heterolepis generally is absent in these more mesic situations.
Phleum pratense is often present in montane grassland habitat in drainage bottoms, varying from occasional to overwhelmingly dominant. It is less common in the southern part of the study area. The mesic mountain meadow phase described by McIntosh (1930) as dominated by timothy is abundant and extensive in drainage bottoms on the Limestone Plateau from Castle Creek north. Meadows strongly dominated by timothy are not included within the Black Hills Montane Grassland association as currently defined. We have little evidence as to the presettlement composition of vegetation at these sites.
Black Hills Montane Grasslands have been described as being forb-rich since the time of Custer''s explorations of the area (Frost 1979). As currently defined, the type includes a range of forb dominance, which may be induced to some degree by grazing. The forb component of stands typically is diverse (often greater than 25 species in a 10x10-m plot), but with a small set of consistent species. These include Geranium viscosissimum, Erigeron subtrinervis, Geum triflorum, Thalictrum dasycarpum, and several Potentilla spp. Oligoneuron rigidum is a native species that is often present, but large populations are indicative of overgrazing. Non-native clovers are the most common exotic forb species found in montane grasslands. They can be locally abundant and extensive.
In the southern part of the study area (south of Castle Creek), shrub cover can be locally high in montane grasslands. Both Symphoricarpos occidentalis and Dasiphora fruticosa ssp. floribunda (= Pentaphylloides floribunda) are occasional grassland components that increase with heavy grazing. The former appears to be more common in drainage bottoms, the latter on lower slopes.
Two geographical variations of Black Hills Montane Grassland have been documented. Within the Central Core just east of the Limestone Plateau, montane grasslands occur mixed with other prairie types on the rolling rocky uplands of Reynolds and Slate Prairies. In the northwestern Black Hills in Wyoming, extensive grasslands are found on the summits of Cement Ridge and Warren Peaks, in areas underlain by igneous rocks. These stands differ somewhat from montane grasslands on the Limestone Plateau in that Festuca ovina is codominant, and Sporobolus heterolepis is absent (Marriott and Faber-Langendoen 2000).
Phleum pratense is often present in montane grassland habitat in drainage bottoms, varying from occasional to overwhelmingly dominant. It is less common in the southern part of the study area. The mesic mountain meadow phase described by McIntosh (1930) as dominated by timothy is abundant and extensive in drainage bottoms on the Limestone Plateau from Castle Creek north. Meadows strongly dominated by timothy are not included within the Black Hills Montane Grassland association as currently defined. We have little evidence as to the presettlement composition of vegetation at these sites.
Black Hills Montane Grasslands have been described as being forb-rich since the time of Custer''s explorations of the area (Frost 1979). As currently defined, the type includes a range of forb dominance, which may be induced to some degree by grazing. The forb component of stands typically is diverse (often greater than 25 species in a 10x10-m plot), but with a small set of consistent species. These include Geranium viscosissimum, Erigeron subtrinervis, Geum triflorum, Thalictrum dasycarpum, and several Potentilla spp. Oligoneuron rigidum is a native species that is often present, but large populations are indicative of overgrazing. Non-native clovers are the most common exotic forb species found in montane grasslands. They can be locally abundant and extensive.
In the southern part of the study area (south of Castle Creek), shrub cover can be locally high in montane grasslands. Both Symphoricarpos occidentalis and Dasiphora fruticosa ssp. floribunda (= Pentaphylloides floribunda) are occasional grassland components that increase with heavy grazing. The former appears to be more common in drainage bottoms, the latter on lower slopes.
Two geographical variations of Black Hills Montane Grassland have been documented. Within the Central Core just east of the Limestone Plateau, montane grasslands occur mixed with other prairie types on the rolling rocky uplands of Reynolds and Slate Prairies. In the northwestern Black Hills in Wyoming, extensive grasslands are found on the summits of Cement Ridge and Warren Peaks, in areas underlain by igneous rocks. These stands differ somewhat from montane grasslands on the Limestone Plateau in that Festuca ovina is codominant, and Sporobolus heterolepis is absent (Marriott and Faber-Langendoen 2000).
Dynamics: Forb dominance may increase with increased grazing pressure. Stands that are strongly forb-dominated probably are artifacts of grazing, as evidenced by the abundance of native increasers such as Oligoneuron rigidum. A single large stand of montane grassland surveyed in Gillette Canyon in the southwestern part of the Limestone Plateau was strongly graminoid-dominated, with forbs contributing less than 20% of the overall cover. It may be that in the absence of grazing, Black Hills Montane Grassland is not as forb-rich as it currently appears to be.
Environmental Description: Stands occur at higher elevations in the western and northwestern Black Hills, where there usually is significant snow cover from November through April. At the highest elevations (above 1983 m [6500 feet]), patchy snow cover persisting through May is not uncommon. Most of the range of the montane grassland lies above 1800 m (5900 feet), with the highest documented site at 2105 m (6900 feet). However, in the northwestern part of the Limestone Plateau in Wyoming, montane grasslands are found in drainage bottoms as low as 1556 m (5100 feet) (in the vicinity of Moskee, for example).
Most montane grasslands occur in the bottoms and on lowermost slopes of broad drainages (100-500 m across), on sites ranging from flat to moderately sloping with variable aspect. However, there are some significant exceptions. Slate and Reynolds prairies northwest of Hill City are large grasslands (greater than 1000 acres each) on rolling uplands. Cement Ridge and Warren Peaks in the northwestern Black Hills in Wyoming are bald (unforested) ridgecrests and summits. More mesophytic stands of this montane grassland type typically occur on deeper soils in drainage bottoms. More xerophytic stands often occur on rockier or thinner soils on slopes, uplands, ridgecrests and summits, and in rocky areas in drainage bottoms.
Stands are most extensive on the Limestone Plateau, on sites underlain by the Paleozoic Pahasapa limestone. Several stands were documented in the adjacent Central Core on sites underlain by Precambrian schist and slate (e.g., Slate and Reynolds prairies). Similar stands have been found at high elevations at two sites in the northwestern Black Hills: Cement Ridge southeast of Sundance, and Warren Peaks in the Bear Lodge Mountains northwest of Sundance. These sites are underlain by Tertiary igneous rocks and include Precambrian granites; the stands differ slightly in floristic composition (Marriott and Faber-Langendoen 2000).
Most montane grasslands occur in the bottoms and on lowermost slopes of broad drainages (100-500 m across), on sites ranging from flat to moderately sloping with variable aspect. However, there are some significant exceptions. Slate and Reynolds prairies northwest of Hill City are large grasslands (greater than 1000 acres each) on rolling uplands. Cement Ridge and Warren Peaks in the northwestern Black Hills in Wyoming are bald (unforested) ridgecrests and summits. More mesophytic stands of this montane grassland type typically occur on deeper soils in drainage bottoms. More xerophytic stands often occur on rockier or thinner soils on slopes, uplands, ridgecrests and summits, and in rocky areas in drainage bottoms.
Stands are most extensive on the Limestone Plateau, on sites underlain by the Paleozoic Pahasapa limestone. Several stands were documented in the adjacent Central Core on sites underlain by Precambrian schist and slate (e.g., Slate and Reynolds prairies). Similar stands have been found at high elevations at two sites in the northwestern Black Hills: Cement Ridge southeast of Sundance, and Warren Peaks in the Bear Lodge Mountains northwest of Sundance. These sites are underlain by Tertiary igneous rocks and include Precambrian granites; the stands differ slightly in floristic composition (Marriott and Faber-Langendoen 2000).
Geographic Range: This montane grassland is best developed on the Limestone Plateau in the high western Black Hills. The zone of occurrences extends from the northwestern Black Hills in Wyoming, about 12 air miles southeast of Sundance, southeast and then south to west of Custer, South Dakota. Most of the Limestone Plateau lies east of the Wyoming/South Dakota stateline with the exception of the northwestern part in Wyoming.
Nations: US
States/Provinces: SD, WY
Plot Analysis Summary:
http://vegbank.org/natureserve/ELEMENT_GLOBAL.2.688947
Confidence Level: Moderate
Confidence Level Comments: No Data Available
Grank: G1G2
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 | CEGL002240 Prairie Dropseed - Richardson''s Needlegrass - Timber Oatgrass Grassland | CEGL002240 | 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: = Sporobolus heterolepis - Achnatherum richardsonii - Danthonia intermedia Herbaceous Vegetation (Faber-Langendoen 2001)
= Sporobolus heterolepis - Achnatherum richardsonii - Danthonia intermedia Herbaceous Vegetation (Marriott et al. 1999)
= Sporobolus heterolepis - Achnatherum richardsonii - Danthonia intermedia Herbaceous Vegetation (Marriott 2000)
= Mountain meadow stage (McIntosh 1930)
= Sporobolus heterolepis - Achnatherum richardsonii - Danthonia intermedia Herbaceous Vegetation (Marriott et al. 1999)
= Sporobolus heterolepis - Achnatherum richardsonii - Danthonia intermedia Herbaceous Vegetation (Marriott 2000)
= Mountain meadow stage (McIntosh 1930)
- Faber-Langendoen, D., editor. 2001. Plant communities of the Midwest: Classification in an ecological context. Association for Biodiversity Information, Arlington, VA. 61 pp. plus appendix (705 pp.).
- Frost, L. A., editor. 1979. With Custer in ''74: James Calhoun''s diary of the Black Hills Expedition. Brigham Young University, Provo, UT.
- Girard, M. [1991]. ECODATA survey of riparian communities of Black Hills National Forest, 1986-1990. Unpublished files, field forms, notes, data analyses and type descriptions. Supervisor''s Office, Black Hills National Forest, Custer, SD.
- Marriott, H. J. 2000. Survey of Black Hills montane grasslands. Prepared for the Wildlife Division, South Dakota Department of Game, Fish and Parks, Pierre, SD.
- Marriott, H. J., D. Faber-Langendoen, A. McAdams, D. Stutzman, and B. Burkhart. 1999. The Black Hills Community Inventory: Final report. The Nature Conservancy, Midwest Conservation Science Center, Minneapolis, MN.
- Marriott, H. J., and D. Faber-Langendoen. 2000. The Black Hills community inventory. Volume 2: Plant community descriptions. The Nature Conservancy, Midwest Conservation Science Center and Association for Biodiversity Information, Minneapolis, MN. 326 pp.
- McIntosh, A. C. 1930. Botanical features of the northern Black Hills. Black Hills Engineer 18:79-101.
- Midwestern Ecology Working Group of NatureServe. No date. International Ecological Classification Standard: International Vegetation Classification. Terrestrial Vegetation. NatureServe, Minneapolis, MN.
- SDNHP [South Dakota Natural Heritage Program]. 2018. Unpublished data. South Dakota Natural Heritage Program, Pierre, SD.
- WNDD [Wyoming Natural Diversity Database]. No date. Unpublished data on file. Wyoming Natural Diversity Database, University of Wyoming, Laramie, WY.