Those who frequent High Park in the spring may spot smoke or flames later this month as part of an annual preservation ritual.

Each spring, the City of Toronto hires experts to set fire to part of the park as a way to preserve its rare black oak woodlands and savannahs.

The controlled burns are part of a long-term management project to protect the forest. Flames burn low to the ground, and consume dried leaves, small twigs and stems. The fires do not affect the larger trees.

The city also uses prescribed burns in Lambton and South Humber Parks.

"These rare vegetation communities are at risk of extinction, not only in Toronto but throughout North America," a statement issued Thursday said.

The city did not provide an exact date, but estimated that the burns would take place sometime between the end of March and middle of April. The date will be selected based on ideal weather conditions, and will be announced 24 hours before being set.

Notices will be placed at park entrances, and people will be restricted from using the areas affected by the burns. There may also be temporary road closures in the park, and restricted access to some of the off-leash dog trails.

"People with asthma or high sensitivity to poison ivy may want to limit their exposure by staying inside and keeping windows closed, or by leaving the area during the burns," the statement said.