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A3982 Great Plains Acidic Rock Outcrop Alliance
Type Concept Sentence: This alliance consists of sparsely vegetated, flat to moderately sloping outcrops of acidic bedrock in the central and northern Great Plains.
Common (Translated Scientific) Name: Great Plains Acidic Rock Outcrop Alliance
Colloquial Name: Great Plains Acidic Rock Outcrop
Hierarchy Level: Alliance
Type Concept: This alliance consists of outcrops of acidic bedrock in the central and northern Great Plains. Species vary widely across the range of this alliance but typically consist of Great Plains taxa that can tolerate the shallow, dry soils. Total vegetation cover is sparse across the outcrops but can be moderate or even dense in small pockets where soil accumulates. Substrate varies from granite and quartzite (in Minnesota) to siltstone, sandstone, shale, and even pockets of gypsum. The outcrops are generally flat to moderately sloping but soil development is limited to cracks or depressions.
Diagnostic Characteristics: This alliance consists of outcrops of acidic bedrock in the central and northern Great Plains. Occurrences may contain areas of steep slopes but are not characterized by the steep slopes of cliffs and bluffs.
Rationale for Nominal Species or Physiognomic Features: No Data Available
Classification Comments: This alliance is defined more by substrate and environmental condition (relatively flat, acidic, rocky slopes) than by floristics.
Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: There is little vegetation on most examples of this alliance. Scattered short shrubs <1 m tall and short grasses and forbs generally <0.5 m tall occur where pockets of soil have accumulated.
Floristics: This alliance has little vegetation cover but a variety of species can be found, depending on the surrounding vegetation. Species of the nearby tallgrass or mixedgrass prairies can be found in cracks and depressions where soil has collected. Forbs can include Oenothera caespitosa, Opuntia spp., Selaginella rupestris, and Phemeranthus parviflorus (= Talinum parviflorum). In Nebraska, Astragalus spatulatus, Cryptantha cana, Ericameria parryi var. howardii, Paronychia jamesii, Paronychia sessiliflora, Penstemon eriantherus, Penstemon glaber, Phlox hoodii, Stephanomeria runcinata, and Tetraneuris acaulis are considered diagnostic of this alliance.
Dynamics: The general lack of soil and sloping nature of many sites create very harsh conditions for plant growth and maintain stands of this alliance. Fire does not carry through this alliance, so shrubs and trees can persist, if they can find pockets of soil and survive the generally xeric conditions. In Minnesota, where precipitation is higher and evaporation lower, rain can collect in small depressions on generally flat outcrops and may allow the formation of ephemeral wetlands (Minnesota DNR 2010).
Environmental Description: This alliance occurs where acidic bedrock is exposed in flat to moderately sloping outcrops. This can be irregularly eroded escarpments or ravines or even ridgetops. The substrate is usually sandstone but can be siltstone. Slopes are not steep over entire stands but there is little to no soil development. Soil that does develop or accumulate is on gently sloping or flat ledges and in cracks. These are small and localized.
Geographic Range: This alliance is found from the central Great Plains in Kansas and Nebraska to southwestern Minnesota, southern Manitoba, and eastern Wyoming.
Nations: CA,US
States/Provinces: KS, MB, MN, ND, NE, SD, WY
Plot Analysis Summary:
http://vegbank.org/natureserve/ELEMENT_GLOBAL.2.900033
Confidence Level: Moderate
Confidence Level Comments: No Data Available
Grank: GNR
Greasons: No Data Available
| Type | Name | Database Code | Classification Code |
|---|---|---|---|
| Class | 6 Open Rock Vegetation Class | C06 | 6 |
| Subclass | 6.B Temperate & Boreal Open Rock Vegetation Subclass | S04 | 6.B |
| Formation | 6.B.1 Temperate & Boreal Cliff, Scree & Other Rock Vegetation Formation | F034 | 6.B.1 |
| Division | 6.B.1.Na Eastern North American Temperate Cliff, Scree & Rock Vegetation Division | D051 | 6.B.1.Na |
| Macrogroup | 6.B.1.Na.2 Great Plains Cliff, Scree & Rock Vegetation Macrogroup | M116 | 6.B.1.Na.2 |
| Group | 6.B.1.Na.2.b Skunkbush Sumac / Blue Grama - Prickly-pear species Cliff, Scree & Rock Vegetation Group | G567 | 6.B.1.Na.2.b |
| Alliance | A3982 Great Plains Acidic Rock Outcrop Alliance | A3982 | 6.B.1.Na.2.b |
| Association | CEGL002047 Siltstone - Sandstone Rock Outcrop Sparse Vegetation | CEGL002047 | 6.B.1.Na.2.b |
| Association | CEGL002294 Shale Barren Slopes Sparse Vegetation | CEGL002294 | 6.B.1.Na.2.b |
| Association | CEGL005261 Redbeds (Siltstone, Sandstone, Gypsum) Sparse Vegetation | CEGL005261 | 6.B.1.Na.2.b |
Concept Lineage: All four associations were in old A.1838 (4 of 8).
Predecessors: No Data Available
Obsolete Names: No Data Available
Obsolete Parents: No Data Available
Synonomy: = Crystalline Bedrock Outcrop (Prairie) Type [ROs12a] (Minnesota DNR 2010b)
- Anderson, R. C. 1999b. Savannas, barrens, and rock outcrop plant communities of North America. Cambridge University Press, New York.
- Faber-Langendoen, D., J. Drake, M. Hall, G. Kittel, S. Menard, C. Nordman, M. Pyne, M. Reid, M. Russo, K. Schulz, L. Sneddon, K. Snow, and J. Teague. 2013-2019b. Screening alliances for induction into the U.S. National Vegetation Classification: Part 1 - Alliance concept review. NatureServe, Arlington, VA.
- Minnesota DNR [Minnesota Department of Natural Resources]. 2010b. Native plant communities of Minnesota. Minnesota Department of Natural Resources, St. Paul. [http://www.dnr.state.mn.us/npc/index.html]
- Rolfsmeier, S. B., and G. Steinauer. 2010. Terrestrial ecological systems and natural communities of Nebraska (Version IV - March 9, 2010). Nebraska Natural Heritage Program, Nebraska Game and Parks Commission. Lincoln, NE. 228 pp.
- Younkin, W. E., Jr. 1970. A study of the vegetation of alpine rock outcrops in northern Colorado. Unpublished thesis, Colorado State University, Fort Collins. 109 pp.