Definitions for "Alvar"
a rare community that consists of areas of thin discontinuous soil overlying horizontal beds of limestone or dolomite found along Great Lakes shorelines. Relatively low tree cover and a distinctive biota that includes elements of rock pavement, prairie, savanna and boreal forest communities characterize them. Among these are regional endemics, some very rare.
a limestone plain
Rare landscape on glaciated horizontal limestone or dolomite bedrock along the Great Lakes shoreline. Alvars are populated by drought-resistant calcium-loving plant species (combination of boreal and prairie species) which are maintained in an open state by drought, wave action and ice formation. These factors retard soil accumulation and the growth of woody species.