Print Report
A3103 Juniperus communis - Picea glauca Alvar Shrubland Alliance
Type Concept Sentence: The juniper alvar shrubland alliance is dominated by tall shrubs (2-5 m tall) or scrub trees, including Juniperus communis, Juniperus virginiana, Thuja occidentalis, and Quercus macrocarpa. It occurs throughout the Great Lakes region of the United States and Canada, on very shallow soils (usually less than 30 cm deep) over flat limestone outcrops (pavements).
Common (Translated Scientific) Name: Common Juniper - White Spruce Alvar Shrubland Alliance
Colloquial Name: Great Lakes Alvar Shrubland
Hierarchy Level: Alliance
Type Concept: Shrubs dominate this juniper alvar shrubland alliance, with over 25% cover of tall, short, and dwarf-shrubs; the average is about 43% cover of shrubs, with less than 10% of that being tall shrubs. A characteristic short (0.5-2 m) to tall (2-5 m) shrub is Juniperus communis, often associated with scrub forms of trees such as Juniperus virginiana, Thuja occidentalis, and Quercus macrocarpa. Tree forms (>5 m tall) of these species may be present, but trees have less than 10% cover in the community. Other less common trees (>5 m tall) that may be present include Carya ovata, Ulmus thomasii, and Fraxinus americana. Characteristic short shrubs (0.5-2 m tall) include Cornus racemosa, Prunus virginiana, Rhus aromatica, and Viburnum rafinesqueanum. Some dwarf-shrubs (under 0.5 m tall) are usually present, including Arctostaphylos uva-ursi and Symphoricarpos albus. Characteristic vines include Toxicodendron radicans and Vitis riparia. The herb layer forms a dry, grassy meadow between the shrubs; average cover of herbs is about 23%. The most abundant herbs are Carex eburnea, Carex umbellata, Danthonia spicata, Iris lacustris, and Oligoneuron album. Less than 50% of the ground surface is exposed limestone bedrock, which is usually covered with lichens, mosses, and algae. Grikes (eroded cracks in the rock up to 2 m or more deep and extending 5-30 m in length) may occur, with shrubs and trees rooted in the cracks. The juniper alvar shrubland occurs throughout the Great Lakes region of the United States and Canada, in northern New York, southern Ontario, northern Ohio, northern Michigan, and eastern Wisconsin. Stands occur on very shallow soils (usually less than 30 cm deep) over flat limestone outcrops (pavements). Moisture varies over the season, but summer droughts are typical. Juniper - white spruce alvar shrublands often occur in a patchy landscape mosaic with other alvar communities, including tufted hairgrass wet alvar grassland, little bluestem alvar grassland, annual alvar pavement-grassland, alvar nonvascular pavement, and poverty grass dry alvar grassland.
Diagnostic Characteristics: Stands occur on very shallow soils (usually less than 30 cm deep) over flat limestone outcrops (pavements), with at least 25% short- to tall-shrub cover, particularly Juniperus communis (dwarf-shrubs such as Juniperus horizontalis are excluded). Moisture varies over the season, but summer droughts are typical.
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: The dominant growth form is short shrubs, although scattered trees with less than 25% total cover are often present.
Floristics: Shrubs dominate this juniper alvar shrubland alliance, with over 25% cover of tall, short, and dwarf-shrubs; the average is about 43% cover of shrubs, with less than 10% of that being tall shrubs. A characteristic short (0.5-2 m) to tall (2-5 m) shrub is Juniperus communis, often associated with scrub forms of trees such as Juniperus virginiana, Thuja occidentalis, and Quercus macrocarpa. Tree forms (>5 m tall) of these species may be present, but trees have less than 10% cover in the community. Other less common trees (>5 m tall) that may be present include Carya ovata, Ulmus thomasii, and Fraxinus americana. Characteristic short shrubs (0.5-2 m tall) include Cornus racemosa (= Cornus foemina ssp. racemosa), Prunus virginiana, Rhus aromatica, and Viburnum rafinesqueanum. Some dwarf-shrubs (under 0.5 m tall) are usually present, including Arctostaphylos uva-ursi and Symphoricarpos albus. Characteristic vines include Toxicodendron radicans and Vitis riparia. The herb layer forms a dry, grassy meadow between the shrubs; average cover of herbs is about 23%. The most abundant herbs are Carex eburnea, Carex umbellata, Danthonia spicata, Iris lacustris, and Oligoneuron album (= Solidago ptarmicoides). Less than 50% of the ground surface is exposed limestone bedrock, which is usually covered with lichens, mosses, and algae.
Dynamics: No Data Available
Environmental Description: Stands are found on exposed rocky hilltops, ridges, and slopes. Soils are thin and contain sand and gravel. Exposed bedrock is common. In the Midwest the bedrock is basalt. High winds move over the ridges and slopes and are an important factor in maintaining the structure of these stands.
Geographic Range: The juniper alvar shrubland alliance occurs throughout the Great Lakes region of the United States and Canada, in northern New York, southern Ontario, northern Ohio, northern Michigan, and eastern Wisconsin.
Nations: CA,US
States/Provinces: MI, NY, OH, ON, QC?, WI
Plot Analysis Summary:
http://vegbank.org/natureserve/ELEMENT_GLOBAL.2.899233
Confidence Level: Moderate
Confidence Level Comments: No Data Available
Grank: GNR
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.Nc Eastern North American Grassland & Shrubland Division | D024 | 2.B.2.Nc |
| Macrogroup | 2.B.2.Nc.5 Shrubby-cinquefoil - Bristleleaf Sedge Calcareous Scrub & Grassland Macrogroup | M507 | 2.B.2.Nc.5 |
| Group | 2.B.2.Nc.5.a Little Bluestem - Prairie Dropseed - Common Juniper Alvar Grassland & Shrubland Group | G061 | 2.B.2.Nc.5.a |
| Alliance | A3103 Common Juniper - White Spruce Alvar Shrubland Alliance | A3103 | 2.B.2.Nc.5.a |
| Association | CEGL005211 White Spruce - Northern White-cedar - Common Juniper / Dwarf Lake Iris - Bristleleaf Sedge Shrubland | CEGL005211 | 2.B.2.Nc.5.a |
| Association | CEGL005212 Common Juniper - (Eastern Red-cedar) - Fragrant Sumac - Downy Arrow-wood / Prairie Goldenrod Shrubland | CEGL005212 | 2.B.2.Nc.5.a |
Concept Lineage: A.808 (Juniperus communis Shrubland Alliance) was defined pretty narrowly as a western Great Lakes type, but included juniper dunes, exclude here.
Predecessors: No Data Available
Obsolete Names: No Data Available
Obsolete Parents: No Data Available
Synonomy: = Alvar Shrubland (Faber-Langendoen 2001)
> Alvar grassland (Edinger et al. 2002)
> Alvar pavement grassland (Edinger et al. 2002)
? Alvar shrubland (Edinger et al. 2002)
> Alvar grassland (Edinger et al. 2002)
> Alvar pavement grassland (Edinger et al. 2002)
? Alvar shrubland (Edinger et al. 2002)
- Chapman, K. A., D. A. Albert, and G. A. Reese. 1989. Draft descriptions of Michigan''s natural community types. Michigan Department of Natural Resources, Lansing, MI. 35 pp.
- Edinger, G. J., D. J. Evans, S. Gebauer, T. G. Howard, D. M. Hunt, and A. M. Olivero, editors. 2002. Ecological communities of New York state. Second edition. A revised and expanded edition of Carol Reschke''s ecological communities of New York state. (Draft for review). New York Natural Heritage Program, New York State Department of Environmental Conservation, Albany, NY.
- 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.
- Faber-Langendoen, D., and Midwest State Natural Heritage Program Ecologists. 1996. Terrestrial vegetation of the midwest United States. International classification of ecological communities: Terrestrial vegetation of the United States. The Nature Conservancy, Arlington, VA.
- 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.).
- Reschke, C., R. Reid, J. Jones, T. Feeney, and H. Potter, on behalf of the Alvar Working Group. 1998. Conserving Great Lakes Alvars. Final Technical Report of the International Alvar Conservation Initiative. The Nature Conservancy, Great Lakes Program, Chicago, IL. 119 pp. plus 4 appendices.