Benefits of Urban Forests

Urban trees, individually or collectively as urban forests, provide diverse ecological services, some of which can be monetized and provide economic value to society. Ecological services of urban forests, in general, include regulating, provisioning, supporting, and cultural services (Filho et al., 2020). Urban forest regulating services have the ability to moderate the environment via climate regulation, flood control, air pollution removal, and carbon storage. Provisioning services provide tangible products such as food, water, wood, and medicinal plants (Visentin, 2019). Supporting services are natural processes that sustain life, including nutrient cycling, soil creation, biodiversity, habitat, oxygen production, photosynthesis, biomass production, erosion control, and the water cycle (Przewoźna, 2022). For example, urban forests support biodiversity through pollination and seed dispersal, and provide wildlife habitats for birds, mammals, and invertebrate species (FAOUN, 2022; Pickett et al., 2016). Cultural services of urban forests benefit humans when they directly or indirectly interact with trees. Compared to regulating, provisioning, and supporting services, cultural services are often harder to quantify and monetize, yet they improve the quality of human life by providing aesthetic, recreational, and restorative values (NWF, n.d.). The practice of urban forestry, which includes management and planning associated with maintaining and protecting urban forests and green spaces, also supports a steady flow of ecological services to society (Tree Canada, 2019; Salmond et al., 2016). It also provides economic benefits in terms of job creation, reduced infrastructure maintenance, and other direct and indirect benefits (Filho et al., 2020).

Climate & Urban Sustainability

With rising concerns about climate instability and government commitments to environmental sustainability and biodiversity conservation, urban forests and urban green spaces are being recognized as natural climate solutions and integral tools for improving the quality of life in urban areas. With nearly 75% of Canadians living in urban/metropolitan areas (StatCan, 2022), integrated land use planning and urban forest management efforts are required to maintain the quality of urban life and city livability in the face of climate change and environmental challenges. 

As the negative impacts of climate change, urban sprawl, and intensified development continue to grow, public awareness of environmental issues is also on the rise. Many people recognize the importance of urban forests and the ecological services they provide. As a result, urban forestry has become a prominent topic in discussions related to municipal policy and decision-making across Canada. Recognizing these challenges and the need to increase urban forest cover to obtain the benefits that trees provide, Canadian cities have set some of the most ambitious urban forest canopy goals. For example, many major Canadian cities, including Vancouver, Halifax, Montreal, Ottawa, and Winnipeg, have pledged to increase urban tree canopy cover by more than 25% by 2030 (CCI, 2021), and Toronto has set an ambitious 40% target by 2050. For example, with over 11.5 million trees and around 1,500 urban parks and green spaces, Toronto has been integrating urban forest into urban land use fabric with an aim to become one of the most forested cities in Canada (City of Toronto, 2024; City of Toronto, n.d.). 

The benefits of urban forests across various land uses and green spaces are far-reaching in Toronto. According to multiple health indicators, notably cardiovascular and respiratory health (StatCan, 2019), Toronto is one of the healthiest cities in Canada. Other Canadian cities, such as Ottawa, Winnipeg, and Metro Vancouver, are also developing and implementing management, operations, maintenance, and protection strategies to manage urban green spaces and receive the full benefits of urban forests and green spaces. Ecological services provided by urban forests and green spaces have been shown to vastly improve the quality of life in urban areas by also improving mental health and promoting social cohesion (Tree Canada, 2019). Epidemiological studies have shown that even brief experiences in natural settings can reduce neural activity in the subgenual prefrontal cortex, indicating a reduction in feelings of stress and anxiety (Bratman et al., 2015). When congruent experiments were conducted in urban areas lacking nature, the same effects were not observed (Bratman et al., 2015).  Medical studies highlight urban naturalized areas and green space as essential for enhancing mental health in urban environments (Astell-Burt & Feng, 2019; Rugel, Carpiano, Henderson & Brauer, 2019). A direct link has also been drawn between tree canopy cover and social capital, where urban neighbourhoods with more tree cover have more social networks and a greater sense of cohesion, and also further benefit from improved mental health (Holtan, Dieterlan & Sullivan, 2014). 

When access to treed green spaces is available, Canadians tend to use them, increasing the likelihood of social interaction while encouraging diverse recreation activities across all demographic spectrums (Koley, Kuo & Sullivan, 1997). Proximity and availability of green space within urban areas encourage physical activity, which further benefits the mental health of urban residents while improving general indicators of physical health (FAOUN, 2022). Greener urban areas have shown a positive association with better cardiovascular health, lower blood pressure, reduced incidences of obesity, asthma and diabetes, and improved memory and attention span (Richardson et al., 2013; Pretty et al., 2006; Kim, Lee & Ramos, 2021; Tree Canada, 2024; Kardan et al., 2015). 

In addition, urban trees are also crucial biofilters because they capture atmospheric pollutants and particulates in city air, keep the air cleaner, and reduce the severity of respiratory-related conditions and illnesses (Wolf et al., 2020). Urban trees in Canada are responsible for sequestering and neutralizing around 2.5 million metric tonnes of atmospheric carbon every year (Steenberg et al., 2023). Trees can reduce ambient temperatures by 2-5 degrees Celsius in urbanized areas, combating negative health outcomes related to high temperatures in summer months (NRCan, 2016).   

Quantifying Urban Forest Benefits 

Urban areas with extensive and diverse green spaces and strong urban forestry practices benefit from increased urban forest ecological services (FAOUN, 2022). Overall, urban forests across cities in Canada provide various benefits, and many municipalities have quantified and mapped urban forest services (i-Tree, 2024; Town of Oakville, 2016). Urban forest inventory and monitoring are a foundational step toward quantifying urban forests and the benefits they provide. Depending on the method and tools used, it is possible to estimate and quantify urban forest services and track them over time by utilizing urban canopy mapping, tree species measurements, and tree health data. 

One such tool used for estimating ecological services is i-TreeEco, developed by the USDA Forest Service. i-Tree provides forestry analysis tools at the level of individual trees to entire stands, benefits assessment tools, and a database to support quantifying forest structure and guide decision-making (i-Tree, n.d.). i-Tree has been used across over 20 municipalities in Canada to estimate ecological services (i-Tree, n.d.).