An alvar is a biological environment based on a limestone plain with thin or no soil and, as a result, sparse grassland vegetation. Often flooded in the spring, and affected by drought in midsummer, alvars support a distinctive group of prairie-like plants. Most alvars occur either in northern Europe or around the Great Lakes in North America. This stressed 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.
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 Kalm's lobelia, Pringle's aster, juniper sedge, lakeside daisy, ram's-head lady's-slipper, and dwarf lake iris. Also associated with alvars are rare butterflies and snails.
Alvars in Ontario include:
The rare Charitable Research Reserve – Cambridge, Ontario
Pelee Island, Ontario – Stone Road Alvar Nature Reserve
Belanger Bay Alvar, Manitoulin Island, Ontario
Quarry Bay Nature Reserve, Manitoulin Island, Ontario
Bruce Alvar Nature Reserve, Bruce Peninsula, Ontario
Baptise Harbour Nature Reserve, Bruce Peninsula, Ontario
Misery Bay Provincial Park, Manitoulin Island, Ontario
Carden Plain Alvar, City of Kawartha Lakes, Ontario, including Carden Alvar Provincial Park
Burnt Lands Alvar, Almonte, Ontario
Balsam Lake Indian Point Provincial Park, Ontario
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