Bruce Peninsula Alvar

October 29, 2008


Photographer: Steve Irvine
Summary Author: Steve Irvine

The Bruce Peninsula in Ontario has some of the world's best examples of limestone alvars. These pavements are flat and open, with little or no soil. Small pits in the pavement surface hold tiny amounts of earth, and these extreme microclimates are of great interest because of the rare or endemic species they contain. In the winter, the alvar will have extreme cold, with ice crystals forming throughout what little soil there is. In the spring, it may be flooded for weeks on end. In the summer, surface temperatures can reach well over 104 degrees F (40 C), drying out everything to a crisp. Only a very limited number of specialized plants and animals can thrive under these conditions, which makes the alvar ecology so unique. Many of the plants here are nationally or provincially rare. The most notable is the Lakeside daisy (Hymenoxys herbacea), which is only found at a dozen or so small sites worldwide. The Federation of Ontario Naturalists bought the Bruce Alvar Nature Reserve in 1993 to protect it from degradation and development. A raised boardwalk through the alvar allows access with minimal disturbance to the environment.