A prescribed burn is a deliberately set and carefully controlled fire. Fire-dependent ecosystems, such as Black Oak savannahs, contain rare native prairie plants that respond positively to burning and grow more vigorously. These burns are a part of the City’s long-term management plan to restore and protect rare Black Oak woodlands and savannahs in Toronto’s High Park, South Humber Park and Lambton Park.
The City of Toronto is currently preparing for a prescribed (or controlled) burn in High Park. The prescribed burn is scheduled to take place early spring 2023, and is contingent on favourable weather conditions.
High Park will be temporarily closed to vehicles on the day of the prescribed burn and will be re-opened once the fire is complete. Refer to the map for exact burn locations within the park planned for this year.
During prescribed burns:
The City uses a variety of different ways to communicate prescribed burn plans and preparation.
Updates on the prescribed burn will be posted on the City’s social media channels as they become available
Notices will be:
News releases will be issued about upcoming prescribed burns. If you have additional questions call 311 (416-392-2489 from outside the city limits).
A prescribed burn is a deliberately set and carefully controlled fire. It burns low to the ground and consumes dried leaves, small twigs and grass stems but does not harm larger trees. Fire-dependent ecosystems, such as Toronto’s rare Black Oak savannah, contain prairie plants that respond positively to burning, and that grow more vigorously than they would in the absence of fire. Species that are not adapted to these ecosystems can be reduced with repeated use of fire. The use of prescribed fire is part of the City’s long-term management plan to restore and protect Toronto’s rare Black Oak woodlands and savannahs.
Prescribed burns are:
The prescribed burn will:
The City of Toronto hires a Fire Boss and their crew who is experienced in high-complexity burns. The Fire Boss and his crew are in charge of the technical aspects of setting and controlling the fire. City staff are responsible for determining the goals and objectives of each burn unit and preparing each site for the planned burn.
The Fire Boss along with City staff, leading experts and members from the Indigenous community visit the site six months before the burn to assess the area and review numerous factors, including the type of fuel on site (leaves, twigs, and stems), topography, proximity to park buildings and private property.
During the winter months, City staff will prepare burn sites by clearing the majority of woody invasive species in the understorey. This helps to increase the light, space and availability to nutrients required for the native seedbank to germinate and flourish after the burn is completed.
Once the snow has melted and weather patterns begin to consistently warm, City staff will begin daily monitoring of on-site ground conditions and report this to the Fire Boss who will determine when the site is ready. The Fire Boss makes this decision by assessing the dryness of the site as well as forecasting the expected temperatures, humidity levels and wind patterns to support a slow-moving fire with high smoke lofting.
Since weather is difficult to predict with certainty, the day of the burn is selected within 24 to 48 hours of the anticipated ideal conditions in spring. On the day of the burn, the Fire Boss will determine the appropriate time to set the fire so that it will remain under control and progress across the site at a walking pace, to ensure safety and the desired effect of setting back undesirable plants.
The Black Oak savannah habitat is extremely rare. It is estimated that less than three per cent of the original pre-settlement cover of prairie and oak savannah ecosystems remain in Ontario.
In Toronto, Black Oak savannah remnants can be found in South Humber Park, Lambton Park and High Park. High Park contains approximately 29 hectares of fragmented savannah and oak woodland, and is the most significant area of remnant prairie and savannah plant communities in the Toronto region. High Park has a healthy population of uncommon and rare savannah plants. This was recognized by the Province of Ontario when it was designated an Area of Natural and Scientific Interest (ANSI) in 1989. South Humber Park, Lambton Park and High Park are all classified as Environmentally Significant Areas (ESA) in the City of Toronto’s Official Plan.
Savannahs are defined by The Ecological Land Classification as widely-spaced open-crowned trees that provide between 25 to 35 per cent canopy cover. These trees are surrounded by a sea of prairie plants including tallgrasses like Big Bluestem and Canada Wild Rye, forbs such as Hairy Beardtongue, Wild Bergamot and Black-eyed Susan, and low-lying shrubs such as Northern Bush Honeysuckle and New Jersey Tea.
What is unique about the Black Oak savannah and one of the reasons why it is so significant, is the incredible diversity of flora and fauna that it supports. It offers a unique array of shade to full sun in sandy soils that appeals to many different species all in one area. This habitat has one of the highest diversity counts of Ontario’s ecosystems.
Savannahs are fire-dependent ecosystems, which rely on burning the landscape in order to maintain them. Fire benefits native plants and helps to sustain a unique habitat for the wildlife that depend on this ecosystem.
Before European settlement, the landscape was defined by Indigenous Peoples’ use of controlled burns to manage the landscape, coupled with naturally-occurring wildfires. Indigenous people would use fire to clear the land for agriculture, to rejuvenate the quality and quantity of forage and medicinal plants, and to attract wildlife. This use of fire also helped to regenerate and maintain savannah habitats.
Prescribed Burns are designed to echo these historic controlled and natural fires and benefit native plants and animals by reducing invasive/exotic plants and grass, stimulating native plant regeneration, restoring wildlife habitat and returning nutrients to the soil.
Toronto’s magnificent oak trees are some of the largest and longest-living trees in the city and their acorns provide food for over 100 species of birds and mammals. One species of oak, the Black Oak has adapted its bark so it can withstand fires which helps it to thrive in fire-dependant ecosystems such as High Park’s Black Oak Savannahs and Oak Woodlands and are a key component to the preservation of these magnificent ecosystems. In fact, Black Oaks need occasional fires to ensure their survival and to promote the successful regeneration of new Black Oaks. As such, they have adapted their leaves to help encourage a low-travelling burn with their thicker leaves that take longer to decompose and the natural curling of the leaves that help fire travel from leaf to leaf.
In 1995, an evaluation of the oaks in High Park determined that the oaks were nearing the end of their life expectancy and the concerning discovery that there were no young oaks or oak seedlings regenerating to replace them. This was due to several key factors including but not limited to the suppression of fire resulting in a build-up of leaf litter which impeded acorns from reaching the soil; excessive population of squirrels eating the acorns; and herbivory on the seedlings that could take root.
Following the reintroduction of controlled fires to the landscape, natural black oak regeneration has once again been observed. Coupled with targeted re-planting efforts of locally sourced Black Oaks and improved conditions for associated savannah species to thrive, the longevity of this important ecosystem is very promising
The burn will temporarily produce large amounts of smoke in the park and the surrounding community. Every precaution is taken to limit the spread of smoke. Under ideal weather conditions, the smoke from the prescribed burn will rise upwards and will not affect park visitors or surrounding neighbourhoods. However, it is possible that weather conditions could change and some smoke will linger in the park.
If people are sensitive to smoke or poison ivy, they are advised to take precautions such as not entering the park during the burn and if they live in the nearby community, that they close all doors and windows.
Parks will be closed to vehicles on the day of the prescribed burn, closing at 7 a.m. and re-opening in the evening. In addition, sections of the park will be closed to pedestrians in order to protect park visitors from areas being burned and to reduce the risk to visitors and their dogs. It will be safe to walk through areas of the park that are not being burned.
Prescribed burns are scheduled at a time of year when birds are not nesting and before hibernating animals emerge. Burn sites are intentionally planned to be small and patchy to allow for wildlife and insect refuge areas, and to preserve unburned areas for overwintering insects, such as pollinators. Large cavity trees that may be home to wildlife are also protected from burning by creating a fire break at the base of the tree.
Immediately prior to burning a site, staff will perform a wildlife sweep. This is achieved by lining up staff the length of the site and they walk together across the site. Through this method, they create ground vibration and movement that encourages wildlife to return to their underground nests safe from the heat of the fire or to leave the site. This also gives the opportunity for staff to observe for any wildlife, people or dogs in the area before ignition.
Post-burn, the continued management of the burn sites is important. Invasive species are opportunists and may attempt to grow into a newly burned site before the native plants in the seedbank have a chance to grow and fill the space. City staff will monitor the burn sites and plan for the management of invasive species as required. Monitoring the sites is an important way of determining both the short and long term success of a site.
The success of the burn is determined by City staff trained in ecosystem management, the Fire Boss, and leading experts from the Ministry of Natural Resources and Forestry (MNRF) and the Toronto and Region Conservation Authority (TRCA).
City staff have established goals and objectives for each unit that is burned, monitored burned areas over many years, and determined the effects of fire on achieving the goals. The main desired effect is to see greater populations of prairie plants and the regeneration of fire-dependent Black Oaks, while at the same time seeing reduced growth and decreased populations of invasive plant species.
According to the TRCA 2019 High Park Biological Inventory Report, High Park has 75 naturally occurring plant species of regional conservation concern with 23 of those being regionally rare. Most of these 23 plants are associated with the oak woodland and savannah habitats in High Park. The report also noted that the populations of some of these rare species are recovering in the burned areas after a steep decline through the 20th century. Some of these species include Wild Lupine, Canada Hawkweed and Cylindrical Blazing Star.