Alvars, rarest of habitats

gentian, silverweed, shrubby cinquefoil, Indian paintbrush, and horned bladderwort to name a few. The place was so remarkable and ethereal I knew I would return often. I told Dan I could have plunked down in one spot for an hour with a good guide book.

Dan, a geology enthusiast, was equally excited. An alvar consists of bare dolomite bedrock with hardly any topsoil. Such landscapes support few trees. In places it stretched flat like pavement. In other places near the beach, the rocks displayed long low ridges, several metres wide and many dozens of metres long, the scoring of glaciers.

The alvar has also become host to a unique assortment of animals which have evolved to exist under such strange extremes. It is the favoured habitat of the threatened Eastern Massassauga Rattlesnake, Canada's only venomous snake.

The threat to alvars

More than half of North America's surviving alvars are in Southern Ontario. They may sound inhospitable, but in fact they usually occur on land in high demand for human use and habitation: along lakes and seashores in temperate climates. Many of Ontario's alvars line the southeast shore of Lake Huron, famous for its wide beaches, warm, shallow bays and breathtaking sunsets.

Ironically it is nature lovers who flock to this popular tourist area and trample its rare plants, which are well-adapted to climatic extremes, but not to human disturbance. The Dorcas Bay alvar was saved from waterfront home development in the 1960s and only added to the Canada's national parks system in 1996. I'm proud of Canada for preserving such a unique habitat.

Our first visit to an alvar is a memory and an episode in our relationship that Dan and I both still cherish. In August 1999 and again last week I returned there with my daughters, hoping to pass along an appreciation for the Earth, and its delicate, richly varied ecosystems.

Alvar resources

Here are some online resources pertaining to alvars:

• Kitchener-Waterloo Record article by Katherine Jacob, published July 3, 2000: "Bruce Peninsula's Singing Sands trail is home to rarest of habitats."
• The International Alvar Conservation Initiative is documenting and evaluation Ontario's most significant alvar sites. This link includes good images of alvar pavement, grassland and savannah. An Ontario Ministry of Natural Resources web page.
• Conserving Great Lakes Alvars, an extensive technical document from the United States Environmental Protection Agency.
• The Great Alvar of Flyway Öland: a Swedish site. The article gives a good overview of the European plant and animal species that inhabit alvars. None of the North American web sites provide anything like this.
• Habitats of the Great Lakes Region, a brief overview of various threatened habitats from Great Lakes Information
  The copyright of the article Alvars, rarest of habitats in Living With Nature is owned by Van Waffle. Permission to republish Alvars, rarest of habitats in print or online must be granted by the author in writing.

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