Common (Translated Scientific) Name: Shrubby-cinquefoil - Bristleleaf Sedge Calcareous Scrub & Grassland Macrogroup
Colloquial Name: Laurentian-Acadian Calcareous Scrub & Grassland
Hierarchy Level: Macrogroup
Type Concept: This macrogroup encompasses calcareous outcrops and alvar grasslands and shrublands that occur in isolated patches in the Laurentian-Acadian region of southeastern Canada and the northeastern United States. Alvars are well-described, and are found in the temperate-boreal transition of the Great Lakes and Lake Winnipeg basins. They are characterized by distinctive scrub and herb flora, of eastern tallgrass prairie elements and eastern subboreal elements, with less than 10% tree cover. Alvars occur both as open grasslands and pavements, with shrubs <25% cover and as shrublands, where shrubs are >25%. Common alvar species include Carex crawei, Carex scirpoidea, Danthonia spicata, Deschampsia cespitosa, Eleocharis compressa, Juniperus horizontalis, Packera paupercula, Schizachyrium scoparium, and Sporobolus heterolepis. In more exposed areas, there is a mosaic of mossy patches and exposed bedrock that is covered with crustose and foliose lichens. In shrubby areas, the dominant shrub is the short to tall shrub Juniperus communis, mixed with Juniperus horizontalis and/or Dasiphora fruticosa ssp. floribunda, or a mix of scrub forms of tree species such as Abies balsamea, Larix laricina, Picea glauca, and Thuja occidentalis. Alvars are maintained by associated geologic, hydrologic, and other landscape processes. In particular, most types of alvar tend to flood each spring, then experience moderate to severe drought in summer months. They include open pavement, grassland, and shrubland/woodland types. Alvar communities occur in an ecological matrix with similar bedrock and hydrologically influenced communities. Four key ecological processes influence Great Lakes alvar communities: (1) hydrology and soil moisture regime, (2) fire regime and land-use history, (3) herbivory: browsing by deer and grazing by cattle, and (4) the invasion of exotic plant species. Calcareous rocky outcrops are poorly described in the region.
Diagnostic Characteristics: Calcareous scrubby-herb vegetation is characterized by a variable physiognomy, from open perennial (rarely annual) grassland or shrubland and nonvascular pavement (5-25% herb and/or shrub cover) to dense grassland or shrubland (>25%) with scattered evergreen needleleaf (more rarely broadleaf deciduous) trees <10% (variable). Species composition contains a mix of calciphilic, sometimes prairie grasses and sub-boreal to boreal shrubs and trees. Sites are on shallow soils over limestone, limestone pavement or alkaline rocky outcrops. Key dominants and differentials on alvars include the perennials Schizachyrium scoparium, Sporobolus heterolepis, Danthonia spicata, and Deschampsia cespitosa (wet to moist areas); Sporobolus neglectus, Sporobolus vaginiflorus, and Panicum philadelphicum occur in areas with the thinnest soils, typically along the margins of exposed pavement. Key shrubs, when present, are Dasiphora fruticosa ssp. floribunda, Juniperus communis, Juniperus horizontalis, and Rhus aromatica. Trees, when present, include Pinus banksiana (in more northern sites), Picea glauca, Thuja occidentalis, and Quercus macrocarpa or Quercus muehlenbergii (more southern sites).
Key characteristics of other calcareous vegetation needs to be documented.
Rationale for Nominal Species or Physiognomic Features: Nominal species are typical calciphiles in the region, but diagnostic value needs to be assessed.
Classification Comments: Excluded from the alvar concept are limestone bedrock lakeshore and rivershore pavement grasslands, and various limestone woodlands. These lack the typical diagnostic species of alvar (Reschke et al. 1998). Limestone spare woodlands (savannas) and woodlands, with >10% tree cover, are treated with Laurentian-Acadian Limestone Woodland Group (G655) in Laurentian-Acadian Pine - Hardwood Forest & Woodland Macrogroup (M159). Juniper shrublands lack many of the diagnostic species common in grassland alvars, and further review is needed to resolve their placement.
Distribution in Lower New England states is uncertain. Depending on whether Central Interior Calcareous Scrub & Grassland Macrogroup (M508) extends to Massachusetts and Connecticut for calcareous/circumneutral outcrops (currently M508 does not), Massachusetts and probably Connecticut have small outlying occurrences; not alvar, but outcrops (e.g., Massachusetts Calcareous Rocky Summit / Rock Outcrop Community). See also Weatherbee (1996) for Massachusetts and state classifications for Connecticut, Massachusetts, and Vermont (P. Swain pers. comm. 2014).
Similar NVC Types:
M057 Eastern North American Coastal Dune, Grassland & Rocky Headland, note:
M508 Central Interior Calcareous Scrub & Grassland, note:
Physiognomy and Structure: Calcareous scrub (low shrubs, stunted or sparse tree) and herb vegetation has very few trees (<10% cover of trees over 5 m tall), a variable cover of shrubs and herbaceous plants, often with exposed bedrock, which may be covered with crustose lichens, mosses, and blue-green algal mats in low-lying areas where water pools. Physiognomy varies from open nonvascular pavement with scattered vascular plants, to grassland, and shrubland or scrub types.
Floristics: Alvars are well-described and are found in the temperate-boreal transition of the Great Lakes and Lake Winnipeg basins. Great Lakes alvars are characterized by distinctive scrub (shrub?) and herb flora of western, northern and southern species, depending on where in the basin they occur, with <10% tree cover. Alvars occur both as open grasslands and pavements, with shrubs <25% cover and as shrublands, where shrubs are >25%. Common alvar species include Carex crawei, Carex scirpoidea (only on Bruce Peninsula and Manitoulin Island in Ontario), Deschampsia cespitosa (not an alvar indicator, found on rocky areas near water throughout Ontario), Eleocharis compressa, Juniperus horizontalis, Packera paupercula (= Senecio pauperculus), Schizachyrium scoparium, and Sporobolus heterolepis. Trichostema brachiatum (= Isanthus brachiatus), Panicum philadelphicum, and Scutellaria parvula are common in all alvars, much more so than Carex scirpoidea. In more exposed areas, there is a mosaic of mossy patches and exposed bedrock that is covered with crustose and foliose lichens. In shrubby areas, the dominant shrub is the short to tall shrub Juniperus communis, mixed with Juniperus horizontalis and/or Dasiphora fruticosa ssp. floribunda (= Pentaphylloides floribunda), Rhus aromatica, or a mix of scrub forms of tree species such as Abies balsamea, Larix laricina, Picea glauca, and Thuja occidentalis.
Further information on other calcareous stands is needed. See Lee et al. (1998) for information in southern Ontario, and state Natural Heritage Program classifications and Weatherbee (1996) in New England.
Dynamics: In Great Lakes alvars, natural fires appear always to have been at least an incidental part of their history, and probably instrumental in maintaining some alvar types, such as juniper alvar shrubland. But based on evidence from alvars that are open with old trees and have no burn evidence, it is clear that not all alvars require fire to remain in an open state. Therefore, the use of fire as a management tool is not advised for all alvar community types (Reschke et al. 1998). Alvars in the Great Lakes basin and elsewhere have long been influenced by grazing livestock. Brownell (1998) has noted that where grazing is intense on Great Lakes alvar grasslands, the grasses may be reduced and that species avoided by cattle such as Eleocharis compressa may increase in abundance. Rosette-forming species such as Symphyotrichum ciliolatum and Solidago species also may increase. Ranunculus fascicularis is much more frequent on some alvars subject to grazing than on adjacent non-grazed sites. Nevertheless, even light grazing tends to result in elimination of certain species, such as the disjunct Orobanche fasciculata (Catling and Brownell 1995). Several exotic species are invasive in alvar communities, including Cynanchum rossicum, Echium vulgare, Hypericum perforatum, Lonicera morrowii, Lonicera tatarica, and Rhamnus cathartica. Poa compressa, which is considered by most experts to be an introduced species, is also well-established on many alvar sites. These exotic species compete with native species for space and nutrients and, in some cases, become dominant (Reschke et al. 1998).
Dynamics of calcareous outcrops needs investigation.
Environmental Description: Alvars are maintained by associated geologic, hydrologic, and other landscape processes. In particular, most types of alvar experience moderate to severe drought in summer months, and some tend to flood each spring depending on topographic position. Soils are often thin (up to 30 cm of soil). Four key ecological processes influence Great Lakes alvar communities: (1) hydrology and soil moisture regime, (2) fire regime and land-use history, (3) herbivory: browsing by deer and grazing by cattle, and (4) the invasion of exotic plant species.
Calcareous rocky outcrops are poorly described in the region. See Lee et al. (1998) for information in southern Ontario, and state Natural Heritage Program classifications and Weatherbee (1996) in New England.
Geographic Range: Open shrub, scrub and herb calcareous rocky vegetation is found in isolated patches in the Laurentian-Acadian region of southeastern Canada and the northeastern United States, from Minnesota and southeastern Manitoba to Maine and Nova Scotia. Distribution in Lower New England states is uncertain.
Nations: CA, US
States/Provinces: MB, ME, MI, MN, NH, NS, NY, ON, PE?, QC, VT, WI
|US Forest Service Ecoregions (2007)|
Northeastern Mixed Forest Province
Confident or certain
St. Lawrence and Champlain Valley Section
Confident or certain
Confidence Level: Low
Confidence Level Comments:
Dasiphora fruticosa ssp. floribunda - Carex eburnea Calcareous Scrub & Grassland Macrogroup
Concept Author(s): D. Faber-Langendoen, in Faber-Langendoen et al. (2014)
Author of Description: D. Faber-Langendoen
Version Date: 15Oct2014
- Brownell, V. R. 1998. Significant alvar natural heritage areas in the Ontario Great Lakes region: A preliminary discussion paper. Prepared for Federation of Ontario Naturalists, Toronto. 54 pp.
- Catling, P. M., and V. R. Brownell. 1995. A review of the alvars of the Great Lakes Region: Distribution, floristic composition, biogeography, and protection. The Canadian Field Naturalist 109:143-171.
- Comer, P., D. Faber-Langendoen, R. Evans, S. Gawler, C. Josse, G. Kittel, S. Menard, C. Nordman, M. Pyne, M. Reid, M. Russo, K. Schulz, K. Snow, J. Teague, and R. White. 2003-present. Ecological systems of the United States: A working classification of U.S. terrestrial systems. NatureServe, Arlington, VA.
- 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, S. Gawler, M. Hall, C. Josse, G. Kittel, S. Menard, C. Nordman, M. Pyne, M. Reid, L. Sneddon, K. Schulz, J. Teague, M. Russo, K. Snow, and P. Comer, editors. 2010-2019a. Divisions, Macrogroups and Groups for the Revised U.S. National Vegetation Classification. NatureServe, Arlington, VA. plus appendices. [in preparation]
- 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.
- 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.
- Swain, Patricia. Personal communication. Natural Community Ecologist, Natural Heritage and Endangered Species Program, Massachusetts Division of Fisheries and Wildlife, Westborough, MA.
- Weatherbee, P. B. 1996. Flora of Berkshire County, Massachusetts. Berkshire Museum, Studley Press, Dalton, MA. 123 pp.