Prescribed Burns in High Park

The Role of Fire

Since 2000 City of Toronto Urban Forestry has been using fire as a management tool to help restore and expand High Park native plant communities including the globally rare Black Oak savannah habitat. Different areas of oak savannah are burned on a rotating cycle. (See Summary of Burn Cycle by Management Unit.)

Prior to European settlement, fire played a pivotal role in maintaining the prairies, savannahs and oak forests that once extended across southern Ontario. This included deliberate burns set by Indigenous peoples as well as naturally occurring wildfires. (See Indigenous History of Today's High Park.)

Fire is an important factor in a healthy oak savannah as it helps to encourage and invigorate native species that have evolved to persist in fire controlled systems. Indigenous peoples used fire to maintain lush grasslands that attracted deer and other game for hunting.

Prairie plants including black oaks respond to modified site conditions following the burn, and grow more vigorously than they would have in the absence of the fire. Fire also works in reducing competition from some invading exotic species that are not adapted to a fire controlled ecosystem.

Successes of the High Park Burn Program

The natural fire cycle had been suppressed in High Park for over 100 years. With fairly regular fires occurring since 2000, large improvements have been observed in the distribution and health of native plant species in the park.

The initial goals for the prescribed burn program established in the management plan focused on enhancing the growth of native species while controlling exotic plant species. Special attention was also focused on targeting small rare plant communities existing in High Park in the hope of encouraging their natural expansion. Annual monitoring has shown that many areas in High Park are exhibiting large increases in native plant community patches, as well as a significant decline in some of the exotic species controlled by burning, such as garlic mustard.

High Park is home to many rare and important species that are thriving from prescribed burning. Species in the drier savannah areas are showing large success in expansion such as dryland blueberry, Indian grass, big bluestem, woodland sunflower, sky-blue aster, and a variety of goldenrods and sedges. Wild lupine populations have exhibited an immediate response, with increases in patch size as well as seed production.

In the beginning stages of the prescribed burn program, frequent burns were necessary to reverse the effects of the approximately 100 years of suppressed fire cycles. More frequent burning was required to set-back exotic invasive plants such as buckthorn and honeysuckle, allowing more light to penetrate into the savannah habitats.

Restoration of natural areas is an adaptive process. As the successes of the High Park prescribed burn program continue, the frequency and interval between burns are reevaluated and adjusted accordingly.

Prescribed burn management, in combination with native species planting and invasive species removal, will continue to be a valuable tool used in these rare habitats to ensure their longevity and proliferation.