Alvar

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This article is about the landform. For the Tamil saints, see Alvars.

An alvar or pavement barren is a limestone plain with thin or no soil and, as a result, sparse vegetation. In the United Kingdom this landform is called a limestone pavement. This environment suffers from poor drainage, so these areas flood in the spring and become very dry and hot in the summer. This challenging habitat supports a community of rare plants and animals, including species more commonly found on prairie grasslands. Lichen and mosses are common species. Trees and bushes are absent or severely stunted. Alvars can be found in southern Sweden, northwest Estonia and around the Great Lakes in Michigan, New York and Ohio in the United States and Ontario in Canada. Alvars comprise a small percentage of the Earth's ecosystems by land extent; although, some 120 exist in the Great Lakes region, they comprise only 0.2% of the land area there.

In North America, alvars provide habitat for birds such as Bobolinks, Eastern Meadowlarks, Upland Sandpipers, Eastern Towhees, Brown Thrashers and Loggerhead Shrikes whose habitat is declining elsewhere. Rare plants include northern bog violet, balsam squaw-weed, Kalm's lobelia, Pringle's aster, Juniper sedge (Carex juniperorum), Lakeside daisy (Hymenoxys acaulis), Ram's-head Lady's-slipper (Cypripedium arietinum) and Dwarf Lake Iris (Iris lacustris). Also associated with alvars are rare butterflies and snails.

The use of the word "alvar" to refer to this type of environment originated in Scandinavia. The largest alvar in Europe is located on the Swedish island of Öland. Here the thin soil mantle is only .5 to 2.0 centimeters thick in most places and in many extents consists of exposed limestone slabs^[1][2]. The landscape there has been designated a UNESCO World heritage site.

Contents 1 European alvar locations 2 North American alvar locations 3 See also 4 References

[edit] European alvar locations

• Sweden
  • Öland - Stora Alvaret - largest alvar extent in Europe
• England
  • Cumbria and North Yorkshire - under protection in the UK Biodiversity Action Plan

[edit] North American alvar locations

• Lake Erie
  • Kelley's Island, Ohio - North Shore Alvar State Nature Preserve[1]
  • Marblehead, Ohio - mostly destroyed by limestone quarrying
  • Pelee Island, Ontario - Stone Road Conservation Area[2]
• Lake Huron
  • Maxton Plains Proposed Natural Area, Drummond Island, Michigan[3]
  • Belanger Bay Alvar, Manitoulin Island, Ontario[4]
  • Bruce Alvar, Bruce Peninsula, Ontario[5]
• Lake Ontario
  • Chaumont Barrens Preserve, New York[6]
  • Three Mile Creek Barrens, New York
  • Near Almonte Ontario, particularly extensive and diverseaccording to Nature Conservancy of Canada
• Balsam Lake
  • Indian Point Provincial Park, Ontario[7]

[edit] See also

• Limestone pavement

[edit] References