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Fire Starters: Understanding High Park’s Prescribed Burn

With wildfires continuing to rage out of control across North America, public opinion waivers on the value of controlled fires. Forests Ontario endeavours to uncover the value of the oft-misunderstood prescribed burn.

On April 15th, rising clouds of smoke were seen and smelled from within Toronto’s High Park well before entering the park. It was still a lovely spring day, however, and cyclists, runners, and dog walkers continued on as normal. The only complainer was a man near the tennis courts who, ironically, was smoking a cigarette.

“We’ve been doing this for about seventeen years or so, so most people know what’s going on and why we’re here,” said Jesse Heinrich of Lands and Forests Consulting (LFC), who administered the burn. “There are always some people whose first response to fire in a place like this is fear or that something is wrong,” Heinrich adds.

Henrich was referring to a prescribed burn that took place across three sites within High Park that day. Burns have been carried out by the City of Toronto since 2000, when the city developed a vegetation management plan for High Park. Burns were introduced to support the growth of prairie plants and patches of Black Oak Savannah in the park.

Prescribed burns are carefully planned and controlled fires that mimic the natural process of forest fires. In the case of the High Park burn, Lands and Forests Consulting developed an official plan (in consultation with the City of Toronto and Ministry of Natural Resources and Forestry) months in advance, taking into consideration temperature, wind patterns, and humidity before setting the date.

High Park is a treasure house of unique vegetation and landscapes. 73 hectares (ha) of High Park’s nautral areas have been designated by the MNRF as Areas of Natural and Scientific Interest (ANSI). In addition to housing 99 rare plant species, approximately 23 ha of fragmented Black Oak Savannah is concentrated within the park. Only 2,100 ha of Ontario’s original oak savannahs remain in the province, having dwindled from two million ha.

One unique feature of oak savannahs is that they are known historically as “fire ecosystems.” Prior to settlement, these ecosystems thrived on naturally occurring forest fires that eliminated leaf litter, twigs, and invasive species without damaging native plants, large trees, and wildlife habitat. Ash created by these fires would act as fertilizer, returning vital nutrients to the soil.

That day, audiences gathered along Centre Road in the park. It was a unique opportunity to watch forestry professionals at work in a way that is usually not available in the city. The High Park site is relatively small compared to rural sites where burns are often carried out. According to Heinrich, it’s typical for LFC to spend a day on a site of 50 hectares.

The burn begins with the Fire Boss moving through the site with a sputtering can dripping a mixture of gasoline and diesel onto the ground while being closely followed by an Extinguisher who controls stray flames. Within minutes the flames spread rapidly across the site and reach as high as one metre, bringing thick clouds of smoke. Within the hour, flames have died down and most of the smoke has cleared, though the burning scent lingers heavily. The ground is blackened, though small patches of unburned landscape remain. Burns are planned to be patchy to provide adequate refuge space for insects and wildlife. In 2015, City staff concluded the coverage of this spring’s burn was excellent, killing or setting back unwanted vegetation while promoting the growth of burn-adapted plants.

“Since the burns began in 2000, the City of Toronto has carefully monitored sites in High Park, and has discerned greater regeneration among the oaks and savannah vegetation in the park, including wild blue lupines,” said Beth McEwen, Manager of Forest and Natural Environment Management, City of Toronto.

In the absence of natural fires, prescribed burns are the only method to ensure the ecological sustainability of many of Ontario’s ecosystems. Forestry consultants like Lands and Forests Consulting have developed safe and effective practices for administering these burns.

To learn more about the process and purpose of prescribed burns, consult the Ontario Ministry of Natural Resources and Forestry’s Prescribed Burn Manual (2014), available online.