The City of Toronto maintains planted and naturalized areas through best management practices such as forest thinning, prescribed burns and controlling invasive plant species. Those practices create healthy forests that provide many environmental benefits. Learn how you can help and what to expect when forest management operations are happening in your area.

2022 Prescribed Burn at High Park

A prescribed burn was successfully completed in High Park on Friday, April 29, 2022, which included four sites. City staff will be monitoring these locations as new growth emerges in the spring and throughout the season, to evaluate the progression of each burn site.

This year was the 16th prescribed burn in High Park and continues the tremendous success of the black oak woodlands and savannah restoration programs Urban Forestry began in 2000. In the fall, City staff will meet to evaluate new burn sites for 2023.

If visiting High Park in early spring, please help to protect the sensitive new growth by remaining on trails.

2022 burn sites:

  • Site 1: located south of the Forestry School
  • Site 2: located south of the Forestry School opposite the Sports Complex
  • Site 3: located south of the Sports Complex just north of Grenadier Restaurant
  • Site 4: located on the east side of the park, south of the Parkside Drive entrance, between Howard Park Avenue and Parkside Drive

The following map has each of these locations shaded in a grey crosshatch pattern.

Map of High Park showing four prescribed burn sites for 2022: two sites located south of the Forestry School; one site located south of the Sports Complex just north of Grenadier Restaurant; and one site on the east side of the park, south of the Parkside Drive park entrance between Howard Park Avenue and Parkside Drive.
2022 High Park prescribed burn sites map

High Park contains remnants of Black Oak savannah, a globally rare and threatened ecosystem.  Prescribed burns are part of Urban Forestry’s long-term management plan to restore and protect Toronto’s rare Black Oak woodlands and savannahs.

About Prescribed Burns

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. It encourages the growth of native savannah vegetation and sets back the growth of undesirable invasive species.

Prescribed burns are:

  • planned and lead by a highly trained Fire Boss
  • controlled by the Fire Boss and a trained crew
  • used on small areas of land to ensure the survival of habitats for birds, butterflies and insects

During prescribed burns:

  • City staff onsite ensure the safety of the public and wildlife and can provide information about the burn
  • park users should be prepared for restricted access to areas near burn sites, including temporary road closures, trail closures and reduced, or no parking
  • smoke from burns will rise and dissipate in ideal conditions, however, weather changes could cause smoke to drift and impact residential areas near the park(s)
  • close windows or consider leaving the area to avoid potential sensitivity to smoke

The prescribed burn will:

  • remain under control
  • progress at a walking pace
  • reduce invasive/exotic species
  • produce brief periods of reduced visibility in the park(s)

Reasons for Prescribed Burns

Toronto is home to the rare black oak savannah ecosystem. Only one per cent of this ecosystem remains after European settlement. This ecosystem can be found in High Park, Lambton Park and South Humber Park.

High Park contains about 23 hectares of fragmented black oak savannah and is the most significant area of the savannah ecosystem in Toronto.

Prior to 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.

Determining a Prescribed Burn date

Once snow has melted and weather patterns begin to consistently warm, City staff will begin daily monitoring of on-site ground conditions including temperature, precipitation, and relative humidity. The burn consultants will use the collected information to forecast the appropriate time window for a prescribed burn.

A burn date is selected once the ground fuels (dried grasses and leaf litter) have dried significantly, and optimal temperature and humidity are met to support a slow moving fire with high smoke lofting.

Additional information

If you have read through this webpage and have additional questions

Pollution, construction, erosion and other factors deteriorate our natural habitats, and invasive species take advantage of the disturbance to thrive. Invasive species compete with native plants for growing space and nutrients. Please keep in mind that invasive species management on public land is done by qualified Urban Forestry staff only.

What You Can Do


  • Plant native species instead of non-native or invasive species on your property.
  • Identify any invasive plants on your property.
  • Use Waste Collection Services to dispose of garden waste and compost.
  • Stop seeds from germinating in disturbed soil by:
    • minimizing tilling and digging on your property
    • keeping pets on leashes
    • staying on designated trails in parks


You may need a permit to Injure or Remove a Tree.

Plant Type Method: Manual Control Method: Chemical Control
Herbaceous Annual or Biennial

(Garlic mustard, Himalayan balsam, tall sweet white clover, burdock)

hand pull or cut close to the base when flowering only in extreme circumstances
Herbaceous Perennial

(Daylily, Dog-strangling vine, Japanese knotweed, goutweed, lily-of-the-valley, Miscanthus grasses, periwinkle, phragmites)

  • hand pull or dig out roots
  • cut repeatedly to weaken roots
  • smother with mulch or black plastic
apply herbicide using spray bottle or sponge:

  • to leaves
  • cut stems of large plants

(Norway maple, Manitoba maple, white mulbery, English ivy, Siberian elm, white poplar, common buckthorn, winged euonymus, non-native honeysuckles, Asiatic bitterwseet,)

  • hand pull or dig up smaller stems
  • cut large vines at base
  • large stems of trees/shrubs
  • girdle large stems of trees/shrubs
cut stems and apply herbicide to stem


Cosmetic use of pesticides is prohibited unless authorized by a permit from the Ministry of Environment, Conservation and Parks.

Learn about invasive insect species control.

Access to the park(s) and its facilities may be limited during a tree thinning. Trails will be cleared of debris but most downed trees will remain to decompose and contribute to the health of the forest.

Tree thinning is a selective removal of trees and shrubs from a densely planted area so that the remaining trees will have better access to growing space, light, water and other nutrients.

During a tree thinning:

  • downed trees will be left behind to decompose unless doing so will be unsafe or cause problems
  • most sites will be replanted with new native trees and shrubs
  • invasive/exotic plants will be prevented by the use of herbicides
    • signs will be posted if herbicides are used

Sites may look different after tree thinning.

Reasons for Tree Thinning

Succession is the natural process of replacement of one group of plants by another group of plants in an area over time. Species that are more tolerant to shade will naturally replace the species that are fast-growing and less shade tolerant.

Tree thinning mimics succession. In the City of Toronto, thinning will be implemented in the areas that were densely planted with a mix of sun and shade-loving trees. Short-lived, sun-loving trees such as poplars provided habitat for the growth of long-living, shade-loving trees such as oaks and maples.

Once the long-living species become well established, the short-living species are removed to reduce the competition for growing space and promote the growth of the shade-loving species.

The Ontario Ministry of Environment, Conservation and Parks Cosmetic Pesticide Ban limits the use of pesticides by homeowners for cosmetic uses. There are exceptions for forestry management, arboriculture, health and safety, and natural resource management. Application of pesticides under these exceptions will require the services of a licensed exterminator.

The City of Toronto uses herbicides under the natural resources management exception to manage larger areas infested by aggressive invasive species that can’t be managed manually.

The City of Toronto uses two Class 9 pesticides regulated by the Pesticides Act.

Roundup Weathermax is the primary herbicide used by the City. It is considered non-toxic.

Garlon RTU is used for species that don’t respond to Roundup Weathermax. It is particularly good for roots. This herbicide can also be used in colder weather. It has a low-toxicity.

Coloured dye is mixed with the herbicides to indicate where it has been used. City staff will post signs indicating the area that has been treated. Please follow the instructions on the signs until they have been removed.

Pesticide use is regulated. Any use of pesticides (including herbicides) is prohibited in the city of Toronto and homeowners shall focus on manual methods of invasive species management.

In 2021, the City of Toronto entered into an agreement with Forests Ontario to provide source-identified native trees and shrubs for the City’s natural area planting programs. This 10-year contract will supply native source-identified trees and shrubs through the Tree Seed Diversity Program to expand nursery capacity and secure increasing amounts of plant material. This long-term agreement will allow the establishment of the required services including seed collection sources, nursery infrastructure and growing time to produce 25,000 native trees and shrubs annually.

Forests Ontario is a leader in tree planting in the province of Ontario and has extensive experience and expertise to carry out the deliverables for the Tree Seed Diversity Program. They have established relationships with a wide group of partners/subcontractor required to support comprehensive planning, seed collection, storage, stock production and delivery.

Planting trees and shrubs grown from seeds, which have been collected from appropriate climatic regions, will improve genetic diversity and support an ecosystem that is more resilient to climate change impacts. This is an important goal of the Toronto Ravine Strategy, Strategic Forest Management Plan, Biodiversity Strategy and the Toronto Green Standard.

More information about the Tree Seed Diversity Program is available on the Forests Ontario website.