Habitat Profile: All About Alvars

A photo of an alvar habitat
Wildflowers on the Carden Alvar, Ontario. Photo by Doug Woods / Getty Images

The alvar habitat may not be as well known as wetlands and forests, but they are equally valuable.

What Are Alvars?

An alvar is a type of habitat within ecosystems, which is defined as, an environment based on a carbonate rock plain, with a shallow layer or no soil, and consequently sparse vegetation. The carbonate rock that forms the base of the alvar habitat is usually limestone or dolostone. Both rocks are easily dissolved by water, making them subject to karstification; the process that shapes the surface of the alvar habitat. 

There are five main types of alvars: shrublands, grasslands, savannahs, pavements and woodlands. Alvar type is determined by the amount of soil present in the landscape, which is typically a range between zero and ten centimetres, over the carbonate bedrock.

Species in Alvars

Vegetation in alvars largely consists of prairie-like plants and is sparse. A variety of rare species of plants and animals make up alvar ecosystems.

Endangered bird species, such as the logger-head strike in Ontario, also find a home in the alvar habitat. The population decline of these birds across north America, makes alvar conservation that much more important to the species survival.

Alvars are perhaps best known for their diversity of tiny creatures, such as invertebrates. Approximately twenty-six species of land snails have been discovered in alvars. Several other insects, rare to the great lake’s region, can also be found in alvar habitats. For example, the Garita skipper butterfly has been spotted several times in the alvars of LaCloche island north of Manitoulin.

The insects inhabiting alvars are an important food source for black bears. Black bears commonly feed on ants in the alvar habitat, which are found in the bedrock. Other animals, such as deer are also found in alvars, often grazing on plants on the outer edge of the habitat.

Alvar Locations

Alvars are globally one of the rarest ecosystems. They are found in only five countries, Canada being one of them.

In North America, approximately 65-75% of alvars are located in Canada, specifically in the Great Lakes Basin in Ontario. Some of the most popular alvar habitats in Ontario include: Manitoulin Island, the Carden Plain and the Bruce Peninsula.

Why Protect Alvars?

The most pressing threats to Alvars in Ontario are from quarrying, agriculture, land development, some recreational activities, the introduction of exotic species and forestry.

Alvars are incredibly rare, only found in a few places globally. However, they are one of the most species-rich communities in the world at a small scale, which makes them incredibly important. The habitat supports many rare species of plants and animals that have adapted to live in conditions specific to alvars. Species of plants and animals in alvars are also an important food source for animals such as black bears and deer.

Through providing an ecotourist spot, alvars also provide economic benefits to local communities.

How You Can Help

Alvar habitats are fragile and vulnerable, so it’s important we actively take steps to protect them. If you are interested in helping protect alvar habitats, here are a few actions you can take:

  • Learn more about alvars in your area. Visit your local library to check out books on the subject.
  • Sign up for a local naturalist group where you can learn from community members about these habitats.
  • When you’re in an alvar habitat remember to tread lightly and avoid cycling or using a motorized vehicle in the area. Alvars are fragile, sensitive ecosystems, easily degraded by this type of activity.
  • If there is an alvar on your land you can enter a conservation agreement with the Nature Conservancy of Canada to protect the habitat.

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