Helping Canada's urban forests adapt to climate change

Urban forests improve the quality of life in cities and towns in many ways. Trees, on both public and private property, increase biodiversity by providing essential wildlife habitat. Through their natural growth systems, trees also improve air and water quality by removing pollutants from the air and reducing stormwater runoff. And trees lessen the “urban heat island” effect (warm temperatures created by human activities and city infrastructure) by adding moisture to the air and creating shade, both of which lower temperatures.

These positive impacts are linked to notable human health benefits, including reductions in stress levels, childhood obesity, and respiratory and cardiovascular illness and increases in longevity. Access to trees has even been linked to improved workplace satisfaction and job performance.

Urban forests provide many economic benefits, too. For example, they create park maintenance and planning jobs, enhance tourism, and increase property values. Trees also extend the life of municipal infrastructure by preventing erosion and flood damage, and they help reduce air conditioning and heating costs by shading homes and buildings. Studies have shown that for every $1.00 spent on urban forest maintenance, city trees provide $1.35 to $12.70 in benefits.

Then there is the benefit of greenhouse gas (GHG) reduction: urban forests help reduce the level of atmospheric carbon dioxide (CO2 ) and other GHGs. Canada’s managed forests absorb vast amounts of carbon annually – equal to the weight of about 424 CN Towers. As urban forests account for about 5% of Canada’s managed forests, that means the atmospheric carbon absorbed by city trees is equal to nearly 2.5 million metric tonnes – the weight of about 21 CN Towers.

However, Canada’s urban forests are being challenged – by development, invasive species and, increasingly, climate change. Extreme weather events, higher annual temperatures and more frequent periods of drought are putting a strain on tree health, and stressed trees face increased risk of disease and insect damage.

Across Canada, cities are testing and promoting a variety of approaches to help urban forests adapt to climate change. For instance, greater genetic diversity in tree species planted offers urban forests protection from catastrophic losses caused by drought, insects such as emerald ash borer, and diseases such as Dutch elm disease. Many communities are also exploring ways to maintain and increase the extent of tree canopy cover. Property owners can help by keeping their existing trees healthy and planting new and more diverse species.

Interested urban residents can express their inner scientist by participating in “citizen science” projects. Often led by governments or non-profit organizations, these projects rely on local residents to record forest and tree observations and relay the information to scientists.

Urban forests in four major Canadian cities

HALIFAX REGIONAL MUNICIPALITY

Halifax
  • 41% urban forest canopy cover
  • $31.37 million total benefits per year

GREATER MONTRÉAL

Montreal
  • 20% urban forest canopy cover
  • $24.44 million total benefits per year

TORONTO

Toronto
  • 30% urban forest canopy cover
  • $81.29 million total benefits per year

GREATER VANCOUVER REGIONAL DISTRICT

Vancouver
  • 43% urban forest canopy cover
  • $224.15 million total benefits per year
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