This Note is part of a series of Notes on key City issues to update City Council at the start of its 2018 – 2022 term.

Issue description

Increased use of Toronto’s green spaces, climate change and the introduction of pests and invasive plants are putting pressure on the city’s ecosystems, leading to degradation and the need for increased maintenance. These spaces, largely ravines and along the waterfront, contribute to the city’s high quality of life and economic prosperity, offering opportunities for recreation and education, stormwater management, clean air and water, biodiversity, and a healthier and more livable urban environment.


An implementation report for the Toronto Ravine Strategy will be brought forward for City Council consideration in 2019. Other City initiatives to manage the pressure on Toronto’s green spaces include the Parkland Strategy and Biodiversity Strategy.


Toronto’s 8,000 hectares in over 1,600 parks cover 13 percent of the city. The Parkland Strategy Preliminary Report estimates this is equal to 28 square meters of parkland per person across the city, less than Los Angeles and Houston and, in City Centres, less than Houston, Chicago and New York. Over the next 15 years, parkland supply per person in Toronto is expected to decrease from 28 m² to 21 m² per person due to population growth.

Chart showing Parkland Per Person Comparisons for Major North American citiesNote: City Centres were measured by selecting the densest census tract and spreading outwards until approximately 250,000 people were selected.

Population Growth and Increasing Use

As the city’s population grows Toronto’s parks and ravines will be affected. Construction can result in injury and loss of trees, impact ravine slope stability, and potentially encroach on parkland. High-density developments of tall buildings can cast shadows across parks, affecting recreation and vegetation. Off-trail use and off-leash dogs can trample sensitive vegetation and lead to soil erosion and other ecological impacts. Roads, cycling and transit uses, which complement and improve access to green space, can also diminish its value if not integrated well.

Climate change

Climate change will have a significant impact on green spaces, ravines and natural areas. Maintaining parks will be more difficult and unpredictable with a more extreme weather events like heat waves, heavy rains and flooding. During droughts, sports fields can dry out, and heavy rains can erode riverbanks and damage trees.

Damage from extreme weather events can be substantial and costly. For example, the combined cost of repairing the waterfront due to the 2017 flood and the 2018 wind storm was $28 million.

Subtle changes can also damage greenspaces. Milder temperatures and reduced snowfall change habitat for fish, plants, and other wildlife while creating conditions for pests and invasive species to thrive. Milder temperatures increase year-round use of parks during typically less active winter months.

Invasive species and introduced pests

Invasive species, such as dog-strangling vine and Norway maples, proliferate and outcompete and replace native species. Introduced pests, such as Emerald ash borer and European gypsy moth, can kill or damage thousands of trees if unmanaged. The ongoing threat of invasive species and introduced pests pose management challenges to the City and require ongoing oversight and action. For example, the introduction of non-native bees can potentially out-compete native bees for food and introduce pests and diseases to native bees.

Actions and Plans

City strategies and plans, listed below, have been developed to address ecosystem pressures and inform green space management. Actions focus on what the City can do alone and with residents, community groups, government agencies, not-for-profits, and private donors.

Existing policies, regulations and programs provide the foundation of protection for the City’s green spaces. Official Plan policies and land use designations and regulations, including the Parks Bylaw, the Ravine and Natural Feature Protection and Tree Bylaws, and Toronto and Region Conservation Authority regulation, help protect Toronto’s parks and natural areas from the impacts of construction and development by regulating removal of trees, change in grade and encroachment onto adjacent parkland. Staff, contractors, and volunteers through the Community Stewardship Program plant and maintain trees and control invasive species.

Date Action
July 2018 Parks and Environment Committee directed staff to undertake public consultation on the Draft Biodiversity Strategy
April 2018 Council adopted the Pollinator Protection Strategy
November 2017 Council adopted the Toronto Ravine Strategy, including a Prioritization Framework
November 2017 Executive Committee adopted the Parkland Strategy Preliminary Report
May 2017 Council adopted the 2017 Wet Weather Flow Master Plan Implementation Status Update
April 2017 The City of Toronto released the Forest Management Plan
November 2016 Council adopted the Actions to Grow Toronto’s Tree Canopy Report