Cliff Ecosystems of the Niagara Escarpment

Incredibly, some of the oldest trees in Canada are Eastern white cedars growing on the cliff faces of the Niagara Escarpment.

A cliff face isn’t the easiest place to survive, and most of the oldest trees are very stunted, measuring less than 7 m in height. The roots grow with little to no soil and anchor themselves in small fissures and cracks in the rock. The oldest trees are often missing bark and look dead. Because of the pull of gravity, some trees have grown in a downwards direction with their crowns beneath the root zone.
Despite their gnarled appearance, these trees are very much alive and have managed to survive the harsh cliff conditions for hundreds of years (over 1000 years in some cases). Ancient cedars have been found on Escarpment cliffs at spots such as Kelso, Mount Nemo, and Inglis Falls Conservation Areas, as well as Metcalfe Rock, Old Baldy, Flowerpot Island, and Lion’s Head Provincial Nature Reserve.

But cedars aren’t the only things growing on Escarpment cliff faces. Other trees such as white birch and mountain maple can also be found growing on the cliff face, albeit less commonly. Robust and colourful lichens and a few species of flowering plants also grow here, along with a range of mosses, algae and cyanobacteria.

Escarpment cliffs also provide a home for a range of fauna. For example, researchers at the University of Guelph identified 44 species of tiny calcium loving land snails, meaning fully half of Ontario’s snails live on Escarpment cliffs. Birds such as the American goldfinch, Nashville warbler and cliff swallow are known to roost on the cliff faces. Even mammals such as white footed-mouse, deermouse, and raccoons find a home on the cliff faces of the Niagara Escarpment.

The cliff ecosystems are relatively unchanged since the retreat of the least glacier. The cliff face is protected from forest fires and floods that are major disturbances in other ecosystems. For example, while a fire raged through almost all the forests of the Bruce Peninsula in 1908, no evidence of fire was found in cliff-side cedars.

As cliff faces are so difficult to access, they are some of the areas least affected by human activity in North America. For example, they remained untouched by loggers while most of the Escarpment was being logged and converted to agriculture between 1800 and 1920.

A new disturbance to these ecosystems is recreational rock climbing, which has increased in popularity over the past 25 years. Research has shown that popular climbing routes have less species diversity and less plant cover. On top of this, non-native weeds are more common once the native vegetation has been lost.

Rock climbing is a fantastic outdoor activity and the Escarpment provides some of the best climbing routes in Southern Ontario. In the interests of conserving the rare cliff face ecosystems on the Escarpment, researchers are encouraging climbers to use popular and designated climbing areas rather than undisturbed areas.

Next time you’re hiking on the Bruce Trail or at a Conservation Area on the Escarpment, take a closer look at the cliff – you might just see one of Ontario’s oldest trees!