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Tortella tortuosa - Cladonia pocillum - Placynthium spp. Sparse Vegetation
Translated Name: Twisted Moss - Cup Lichen - Black-thread Lichen species Sparse Vegetation
Common Name: Alvar Nonvascular Pavement
Unique Identifier: CEGL005192
Classification Approach: International Vegetation Classification (IVC)
Summary: Alvar nonvascular pavement is a rock outcrop community that occurs throughout the Great Lakes region of the United States and Canada, from central and southern Ontario to northern parts of Michigan, Ohio, and New York. Stands occur on flat limestone and dolostone outcrops (pavements). Soils of alvar nonvascular pavement are either lacking or very shallow (usually less than 10 cm deep). This community typically has a soil moisture regime characterized by severe summer drought, as well as high summer temperatures. Alvar nonvascular pavements usually occur in a patchy landscape mosaic with other alvar communities, including annual alvar pavement-grassland, creeping juniper - shrubby-cinquefoil alvar pavement, little bluestem alvar grassland, tufted hairgrass wet alvar grassland, and juniper alvar shrubland. Alvar nonvascular pavement consists of exposed, flat limestone or dolostone pavement that is sparsely vegetated with a mosaic of mossy patches and exposed bedrock that is covered with crustose and foliose lichens. In the mossy patches, characteristic mosses are Tortella tortuosa, other Tortella spp., and Tortula ruralis; a characteristic lichen is Cladonia pocillum. On exposed pavement patches, characteristic lichens are Placynthium nigrum and Dermatocarpon cf. miniatum. Very small herbs (under 15 cm [6 inches] tall), grow in the mossy patches, including Saxifraga virginiensis, Penstemon hirsutus, Potentilla norvegica, Trichostema brachiatum, Fragaria virginiana, Minuartia michauxii var. michauxii, and Houstonia longifolia. Some taller herbs and low shrubs grow primarily in slightly deeper soils of rock crevices that crisscross the pavement, including Solidago nemoralis, Symphoricarpos albus, Vitis riparia, Aquilegia canadensis, and Hieracium piloselloides. There is usually less than 15% cover of herbs. Usually a few trees and shrubs are rooted in deep crevices of the pavement; characteristic trees and shrubs that occur sparsely include Thuja occidentalis, Juniperus communis, Betula papyrifera, Juniperus virginiana, Juglans cinerea, and Picea glauca. There is less than 10% total cover of trees, and less than 10% total cover of shrubs. There is a lot of exposed bedrock, and much of it is covered with lichens and mosses (average cover of lichens and mosses is about 55%).



Classification

Classification Confidence: High
Classification Comments: Alvar nonvascular pavements usually occur in a patchy landscape mosaic with other alvar communities, including Annual Alvar Pavement Grassland, Sporobolus neglectus - Sporobolus vaginiflorus - Trichostema brachiatum - Panicum philadelphicum - (Poa compressa) Alvar Grassland (CEGL005235); Creeping Juniper - Shrubby-cinquefoil Alvar Pavement, Juniperus horizontalis - Dasiphora fruticosa / Schizachyrium scoparium - Carex richardsonii Dwarf-shrubland (CEGL005236); Little Bluestem Alvar Grassland, Sporobolus heterolepis - Schizachyrium scoparium - (Carex scirpoidea) / (Juniperus horizontalis) Grassland (CEGL005234); Tufted Hairgrass Wet Alvar Grassland, Deschampsia cespitosa - (Sporobolus heterolepis, Schizachyrium scoparium) - Carex crawei - Packera paupercula Grassland (CEGL005110); and Juniper Alvar Shrubland, Juniperus communis - (Juniperus virginiana) - Rhus aromatica - Viburnum rafinesqueanum / Oligoneuron album Shrubland (CEGL005212).

Vegetation Hierarchy
Class 2 - Shrub & Herb Vegetation
Subclass 2.B - Temperate & Boreal Grassland & Shrubland
Formation 2.B.2 - Temperate Grassland & Shrubland
Division 2.B.2.Nc - Eastern North American Grassland & Shrubland
Macrogroup Laurentian-Acadian Calcareous Scrub & Grassland
Group Great Lakes Alvar
Alliance Great Lakes Alvar Grassland

This is the revised vegetation hierarchy. For more information see Classification Sources and usnvc.org.

Similar Associations
Unique Identifier Name
CEGL005235 Sporobolus neglectus - Sporobolus vaginiflorus - Trichostema brachiatum - Panicum philadelphicum - (Poa compressa) Alvar Grassland
CEGL005236 Juniperus horizontalis - Dasiphora fruticosa / Schizachyrium scoparium - Carex richardsonii Dwarf-shrubland



Related Concepts from Other Classifications

Related Subnational Community Units
These data are subject to substantial ongoing revision and may be out of date for some states.
In the U.S., contact the state Heritage Program for the most complete and up-to-date information at: http://www.natureserve.org/natureserve-network.
Information from programs in other jurisdictions will be posted when they are made available.
Subnation Concept Name Relationship to Standard Confidence Reference
Michigan Alvar Broader   Kost et al. 2007
Ohio Alvar Broader   ONHD unpubl. data


Other Related Concepts
Related Concept Name: Tortella tortuosa - Cladonia pocillum - Placynthium spp. Sparse Vegetation
Relationship: = - Equivalent
Reference: 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.).
Relationship: = - Equivalent
Reference: 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.

Ecological Systems Placement

Ecological Systems Placement
Ecological System Unique ID Ecological System Name
CES201.721 Great Lakes Alvar


NatureServe Conservation Status
Global Status: G2 (31Dec1998)
Rounded Global Status: G2 - Imperiled
Reasons: Alvar nonvascular pavement is a rock outcrop community that occurs throughout the Great Lakes region on flat outcrops of limestone and dolostone. The largest examples are in Ontario, Canada near Lake Huron on the southern shore of Manitoulin Island and the western shore of the Bruce Peninsula; smaller examples are found in other parts of southern Ontario, northern Michigan, northern Ohio (Kelley's Island), and northern New York. Alvar nonvascular pavements usually occur in small to large patches; sizes of currently documented patches range from under 1.25 acres to over 200 acres (<0.5 to >80 ha). Nineteen occurrences of this community that met the minimum mapping criterion of at least 1.25 acres (0.5 ha) have been documented, with a total area of about 1424 acres (576 ha). This community is frequently observed in small patches (often smaller than 1.25 acres) within other alvar communities.

Distribution
Color legend for Distribution Map
United States Distribution: MI, NY, OH
Canadian Province Distribution: ON
Global Distribution: Canada, United States
Global Range: Alvar nonvascular pavement is a rock outcrop community that occurs throughout the Great Lakes region of the United States and Canada, from central and southern Ontario to northern parts of Michigan, Ohio, and New York. Stands occur in Ontario, near Lake Huron on the southern shore of Manitoulin Island and the western shore of the Bruce Peninsula, as well as in other parts of southern Ontario, northern Michigan, northern Ohio, and northern New York.

U.S. Forest Service Ecoregions
Domain Name: Humid Temperate Domain
Division Name: Warm Continental Division
Province Name: Laurentian Mixed Forest Province
Province Code: 212 Occurrence Status: Confident or certain
Section Name: St. Lawrence and Champlain Valley Section
Section Code: 212E Occurrence Status: Confident or certain
Section Name: Northern Great Lakes Section
Section Code: 212H Occurrence Status: Confident or certain
Section Name: Lake Huron Section
Section Code: 212P Occurrence Status: Confident or certain
Division Name: Hot Continental Division
Province Name: Eastern Broadleaf Forest (Continental) Province
Province Code: 222 Occurrence Status: Confident or certain
Section Name: Lake Erie Section
Section Code: 222Q Occurrence Status: Confident or certain


Vegetation

Vegetation Summary: Alvar nonvascular pavement consists of exposed, flat limestone or dolostone pavement that is sparsely vegetated with a mosaic of mossy patches and exposed bedrock that is covered with crustose and foliose lichens. In the mossy patches, characteristic mosses are Tortella tortuosa, other Tortella spp., and Tortula ruralis; a characteristic lichen is Cladonia pocillum. On exposed pavement patches, characteristic lichens are Placynthium nigrum and Dermatocarpon cf. miniatum. Very small herbs (under 15 cm [6 inches] tall) grow in the mossy patches, including Saxifraga virginiensis, Penstemon hirsutus, Potentilla norvegica, Trichostema brachiatum, Fragaria virginiana, Minuartia michauxii var. michauxii, and Houstonia longifolia. Some taller herbs and low shrubs grow primarily in slightly deeper soils of rock crevices that crisscross the pavement, including Solidago nemoralis, Symphoricarpos albus, Vitis riparia, Aquilegia canadensis, and Hieracium piloselloides. There is usually less than 15% cover of herbs. Usually a few trees and shrubs are rooted in deep crevices of the pavement; characteristic trees and shrubs that occur sparsely include Thuja occidentalis, Juniperus communis, Betula papyrifera, Juniperus virginiana, Juglans cinerea, and Picea glauca. There is less than 10% total cover of trees, and less than 10% total cover of shrubs. There is a lot of exposed bedrock, and much of it is covered with lichens and mosses (average cover of lichens and mosses is about 55%) (Reschke et al. 1998).

Vegetation Composition (incomplete)
Species Name Rounded Global Status Growth Form Stratum Charact-
eristic
Dominant Constant
Cover Class %
Con-
stancy
%
Tortella tortuosa G2 Moss Nonvascular  
 
 
Cladonia pocillum G2 Lichen Nonvascular    
 
 
Placynthium nigrum G2 Lichen Nonvascular    
 
 


Environmental Setting

Wetland Indicator: N
Environmental Summary: Stands occur on flat limestone and dolostone outcrops (pavements). Soils of alvar nonvascular pavement are either lacking or very shallow (usually less than 10 cm deep). This community typically has a soil moisture regime characterized by severe summer drought, as well as high summer temperatures (Reschke et al. 1998).


Dynamic Processes


Plot Sampling & Classification Analysis

Plots stored in VegBank


Authors/Contributors
Concept Author(s): C. Reschke et al. (1998)
Element Description Edition Date: 22Apr1999
Element Description Author(s): C. Reschke
NatureServe Conservation Status Factors Edition Date: 31Dec1998
NatureServe Conservation Status Factors Author(s): C. Reschke

Ecological data developed by NatureServe and its network of natural heritage programs (see Local Programs) and other contributors and cooperators (see Sources).


References
  • Edinger, G. J., D. J. Evans, S. Gebauer, T. G. Howard, D. M. Hunt, and A. M. Olivero, editors. 2014a. Ecological communities of New York state. Second edition. A revised and expanded edition of Carol Reschke's ecological communities of New York state. New York Natural Heritage Program, New York State Department of Environmental Conservation, Albany, NY.

  • 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.).

  • Kost, M. A., D. A. Albert, J. G. Cohen, B. S. Slaughter, R. K. Schillo, C. R. Weber, and K. A. Chapman. 2007. Natural communities of Michigan: Classification and description. Report No. 2007-21, Michigan Natural Features Inventory, Lansing. 314 pp. [http://web4.msue.msu.edu/mnfi/reports/2007-21_Natural_Communites_of_Michigan_Classification_and_Description.pdf]

  • Lee, H., W. Bakowsky, J. Riley, J. Bowles, M. Puddister, P. Uhlig, and S. McMurray. 1998. Ecological land classification for southern Ontario: First approximation and its application. Ontario Ministry of Natural Resources, Southcentral Science Section, Science Development and Transfer Branch. SCSS Field Guide FG-02.

  • Midwestern Ecology Working Group of NatureServe. No date. International Ecological Classification Standard: International Vegetation Classification. Terrestrial Vegetation. NatureServe, Minneapolis, MN.

  • ONHD [Ohio Natural Heritage Database]. No date. Vegetation classification of Ohio and unpublished data. Ohio Natural Heritage Database, Division of Natural Areas and Preserves, Ohio Department of Natural Resources, Columbus.

  • ONHIC [Ontario Natural Heritage Information Centre]. 2018. Unpublished data. Ontario Natural Heritage Information Centre, Ministry of Natural Resources, Ontario, Canada.

  • 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.


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