In cities, trees play a key role in creating healthy urban environments. Many citizens see trees as an important measure of the quality of their communities. In North America and internationally, there is a growing body of research that supports the importance of maintaining healthy, sustainable urban forests.
New technologies are allowing researchers to quantify the services provided by trees and confirm their value as vital green infrastructure. Unlike conventional or “grey” infrastructure, which begins to decay and depreciate the moment it is installed, the value of a properly maintained tree actually increases over its functional lifespan. By all measures of urban sustainability, trees are simply a good investment.
In 2007, the General Manager of Parks, Forestry and Recreation recommended undertaking a city-wide tree canopy study. In collaboration with the USDA Forest Service and The University of Vermont, Spatial Analysis Laboratory, Toronto Urban Forestry has taken advantage of sophisticated modeling and remote sensing tools to paint a more detailed picture of Toronto's urban forest.
The resulting study is entitled Every Tree Counts: A Portrait of Toronto's Urban Forest, published in 2010 and updated in 2013. Key findings include:
- Toronto has an estimated 26.6 - 28% tree canopy cover, representing 10.2 million trees.
- Of the total population, 6.1 million (60%) trees are on private property, 3.5 million (34%) trees are in parks and ravines, and 0.6 million (6%) trees are on city streets.
- Tree cover increased slightly (1.3%) between 1999 and 2009.
- Between 2004 and 2012, the City and its partners planted almost 100,000 trees per year.
- There are at least 116 different tree species in the City.
- The 10 most common species account for 57.7% of the total trees in the population.
- The urban forest provides the equivalent of more than $28.2 million dollars in ecological services each year.
- Toronto's urban forest is estimated to reduce energy use from heating and cooling of residential buildings by $10.2 million annually.
- Air quality improvements, through the interception of pollutants equals $16.9 million per year.
- Toronto's trees store 1.1 million metric tonnes of carbon, or the yearly equivalent of 733,000 car emissions.
- The structural value of Toronto's urban forest is estimated at $7.1 billion
- The benefits derived from Toronto's urban forest exceed the annual cost of management.
This study shows that Toronto supports a reasonably healthy, diverse forest. The forest provides multiple benefits to the residents of Toronto, including ecological services, recreational and health benefits as well as economic spin-offs in the real estate and commercial sectors. Active management and stewardship on public lands are improving the health and resiliency of natural areas in Toronto. Community participation in volunteer tree planting and stewardship events continues to grow.
Consistent with these efforts, a change analysis suggests that forest cover increased slightly over the ten year period between 1999-2009. There are imminent threats to the tree canopy from invasive forest insects, continuing challenges related to managing invasive plant species in the city’s natural areas as well as uncertainty related to climate change effects. Urban growth objectives for the City will lead to increased pressure on green space and trees over the next several decades. All of these factors must be considered in the development of strategies to increase and maintain a sustainable urban forest.
In 2013, Toronto City Council approved a first ever Strategic Forest Management Plan (PDF) which includes the strategic goal of increasing canopy cover in Toronto to 40%.