Alvar

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

Alvar on the shoreline of Lake Erie's Kelley's Island

An alvar or pavement barren is a limestone plain with thin or no soil and, as a result, sparse vegetation. 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 are a rare habitat; although, some 120 exist in the Great Lakes, they comprise only 0.2% of the land area.

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.

File:Alvar2.jpg

Lichen, moss and grasses on limestone surface

The use of the word "alvar" to refer to this type of environment originated in Scandinavia. A large alvar is located on the Swedish island of Öland. The landscape there has been designated a UNESCO World heritage site.

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