Rock It! Cliffs & Alvars | Carolinian Canada

Rock It! Cliffs & Alvars

The Niagara Escarpment is best known for its beautiful hiking trails and rock climbing, but it is also home to rare rockland communities. Rocklands occur where bedrock is exposed or covered with a thin layer of earth. Most of the Carolinian Life Zone is covered by more recent glacial deposits and there are only a few bedrock exposures, primarily along the Niagara Escarpment and on Pelee Island, where the bedrock is calcareous limestones and dolostones.

Cliff face, cliff rim and talus communities may be open, shrubby or treed. Soil is non-existent, or very shallow or confined to crack and fissures. Plants usually survive by pushing roots deep into narrow cracks between the rocks. Some trees on exposed faces may be extremely slow growing and Eastern White Cedars hundreds of years old are found on inaccessible cliffs.

Exposed bedrock may be vertical, forming cliffs, cave and crevices and talus slopes of broken rock, or horizonal, forming alvars. Alvar communities that develop on horizontal or gently sloping rock exposures have generally shallow soils that are wet in the springtime, but quickly dry out in the summer. A distinct suite of plants are associated with alvars, some of them shared with prairie and sand dune sites. Most alvars in the Carolinian Zone are dominated by grasses and herbs, but a few have shrubs or trees.

Protected Areas

  • Stone Road Alvar on Pelee Island is partially protected by Ontario Nature, Essex Region Conservation Authority and the Nature Conservancy of Canada. The Pelee Island Heritage Centre offers an audio tour of the site.
  • UNESCO named the Niagara Escarpment a World Biosphere Reserve in 1990 recognizing it as an internationally significant ecosystem for its special environment and unique environmental plan.
  • Hamilton Region Conservation Authority manages 40 km of trails in the Dundas Valley, one of the most spectacular and diverse spots along the Niagara Escarpment with 1,200 hectares of Carolinian forests, fields, cold-water streams and stunning geological formations.
  • The Bruce Trail club has been active in securing land and conservation easements along its length.
  • The Niagara Peninsula Conservation Authority manages several areas along the escarpment, providing opportunities to explore rock outcrops, ice caves and breathtaking views of the Lake Ontario shoreline.

What’s the problem?

Because the area of exposed bedrock is so small, there are only a few rockland communities in the Carolinian Zone and most of them are rare or uncommon. Some of these habitats and the species dependent on them are being lost to logging, quarrying, and development. Plants are sometimes trampled by hikers or grazed by domestic animals.

Recovery Strategies

Tallgrass Community covers many of the alvar habitats

Habitat Saving Ideas

Planning for Life! The Niagara Escarpment Commission (NEC) established in 1973 provides for the maintenance of the Escarpment as a continuous natural environment and ensure only such development occurs as is compatible with that natural environment. The Niagara Escarpment Plan works with municipalities to provide zoning protection for critical areas.

Watch out! Many people enjoy hiking on the Niagara Escarpment and at Stone Road Alvar, but special care should be taken to stay on marked paths to avoid trampling delicate species.

Plant Communities @ Risk

Canada Bluegrass-Nodding Onion Alvar Grassland

G1?S1. Likely very rare globally, very rare in Ontario

Open alvar with shallow soil and patches of exposed rock. Dominated by Canada Bluegrass with Nodding Onion and Grey-headed Coneflower, there are also scattered shrubs of dogwoods, Downy Arrowwood and Fragrant Sumac. Less that 50% vegetation cover. Nodding Onion has clusters of small white flowers which droop (nod) toward the ground.

Where? In Canada found only on Pelee Island

What’s the problem? Disturbance by grazing and trampling, loss of habitat to development

How to Help! Stick to the trails when visiting an alvar. Protect alvar from development.


Species @ Risk

Hart’s-Tongue Fern (Asplenium scolopendrium)

G4S3. Special Concern in Canada

This evergreen fern with strap-shaped fronds, up to 42 cm long grows in exposed, rocky crevices and outcrops of calcareous rocks. Moist, mossy areas seem to be essential for spore germination and early plant development. In Ontario, many populations are on north-facing slopes under hardwood canopy.

Where? Ontario has the bulk of the North American populations along the Niagara Escarpment.

How many? In Ontario, about 70 sites with one to tens of thousands of plants

What’s the problem? The range of the species is restricted and fragmented by logging, quarrying, development, competition from weeds and trampling from hikers.

How to Help! About half of the known sites in Ontario are on public land, where they receive some protection. Protect habitat from excessive trampling, maintain forest cover, manage invasive species

Peregrine Falcon Falco peregrinus

G4S2. Threatened in Canada, Endangered in Ontario

Falcons are birds of prey that are smaller and more streamlined than hawks, with long pointed wings that enable them to fly at great speed. The Peregrine is a crow-sized falcon. It nests on cliffs or tall urban buildings. A female raised on a tall building in London became the first bird to nest on a natural cliff face [at Niagara Falls] in the Carolinian Zone.

Where? Throughout Canada. In the Carolinian Zone this species has bred in Toronto, Oakville, Hamilton, St. Catherines and London and at Niagara Falls.

How many? About 8 pairs nesting in the Carolinian Zone in 2003

What’s the problem? The highest mortality comes from collisions with window glass on buildings, especially when the young birds first fledge from the nest.

How to Help! Most nest sites have a Peregrine Watch where volunteers rescue downed birds and return them to the tops of the buildings with the cooperation of the building owners.


Carolinian Canada Coalition 2009

Content based on 2004 guide by Michelle Kanter, Dave Martin, Veronique LeHouk, and Jane Bowles

Many Thanks to Photographers who donated their work for this project:
Jane Bowles, Allen Woodliffe, John Ambrose, Scott Gillingwater, Ben Porchuk, Rob Willson, Mathis Nativik, Shawn Staton, David Mihilik, Joe Milner, George Brackx, Kevin Railsback, Hamilton Conservation Authority, Essex Region Conservation Authority, Margaret Pickles, Leora Berman, Donald Kirk, Upper Thames River Conservation Authority, Larry Lamb, Peggy Hurst, Michelle Kanter, Gregory Peck, Jim Flynn and Rick Battson. 

Thanks also to expert support from Dan Kraus, Mike Nelson and Paul Smith.

 Assistance for this project was provided by the Ministry of Natural Resources.


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