The Trees Lining our Streets: Diversity and equity of Canada’s street trees

Cities across Canada are working to grow their urban forest based on the range of environmental, social, and health benefits provided by trees. These benefits include cooling during hot summer months, reduction in local flooding vulnerability, fostering community cohesion and a sense of place, and contributing to positive mental and physical health outcomes. The number of trees, their size, and species composition influence the type and extent of benefits created. However, most benefits are localized: experienced in the immediate area adjacent to the trees. As a result, an even spatial distribution of trees is important to ensure that all urban residents are receiving those benefits.

Drawing on a recently created repository of municipal street tree inventories across Canada, Alexander Martin (MSc ‘25, Department of Geography & Planning, U of T) and Tenley Conway (Professor, Department of Geography, Geomatics and Environment, UTM) examined the density, size, and species of street tree assemblages in 32 Canadian cities to understand if trees are spatially distributed evenly and if distributions of street trees unfairly burden marginalized populations. They calculated the Gini index, a measure of inequality, to determine if trees are evenly distributed. They then conducted regression analyses using variables from the Canadian Index of Multiple Deprivation to determine if marginalized communities are inequitably associated with fewer, smaller, or less diverse trees in their neighbourhoods.

There are substantial inequalities in street tree distribution in the 32 cities, and also inequities associated with population density and four measures of socio-economic deprivation. However, specific street tree inequities varied between cities, highlighting the importance of understanding local context. Cities should address inequities, ensuring all residents equally benefit from street trees. Steps toward just street tree assemblages include planning for adequate space for large trees to thrive, focusing on diversifying species in neighbourhoods with high populations, supporting street tree planting and stewardship in marginalized communities, and using tools like the Gini index to track progress over time.

Comparing Canada’s street trees populations

Canada’s 32 cities contain over 3 million street trees, with the number of trees ranging from 9,787 trees in New Westminster, B.C. (population 78,916 in 2021) to 652,547 trees in Toronto (population 2,731,571 in 2021). All municipalities have more small trees and fewer large trees than recommended size class benchmarks, which may be a result of smaller stature trees being planted or a dominance of young trees that have not yet reached their mature height.[1]

Collectively, there is a diversity of species planted along Canada's city streets, with 726 street tree species across the 32 study cities. Vancouver has the most species (373), while Regina has the fewest (29). In most cities a few species dominate, with just four species representing 34% of the trees in the dataset. This is even more pronounced in the six Prairie cities in the dataset, with green ash and American elm comprising more than half of their street trees.

The percentage of each municipality’s street trees that are native species is highly variable, ranging from just under 5% in Maple Ridge B.C. to 89% in Regina, Sask.. While warmer Canadian municipalities have a larger number of species, they also tend to have a smaller percentage of native street trees. Additionally, there are notable differences between nearby cities. For example, in Ontario, St. Catherines has 28% native street trees and Welland has 48%, but they are only 25 km apart. This suggests that management decisions, in addition to climate and other biophysical factors, are important influences on what species are present in a given city.

Street tree equality

Street tree equality is reached when there is an even spatial distribution of trees, which can provide similar levels of benefits to all neighbourhoods in a city. Many Canadian municipalities are working to create more equal distributions of urban trees.

Conway and Martin set out to explore if street tree populations are equally distributed across each city. To measure equality, they used the Gini Index. Traditionally, the Gini Index has been used to measure income (in)equality, but in recent years it has been applied to understanding inequalities in urban tree distributions. Index values less than 0.2 are generally considered to represent equal distributions and those over 0.5 indicate significant disparity. However, benchmarks specific to urban forests have not been identified.

The curves show relatively high levels of inequality for neighbourhood tree count (median Gini = 0.401), with Fredericton, N.B. having the most equal distribution (Gini = 0.259) and Maple Ridge, B.C. (Gini = 0.681) having the least. The distribution of neighbourhood basal area, a measure reflecting the cumulative volume of trees associated with the magnitude of benefits produced, showed a median Gini value of 0.469, with highest equality in Windsor, Ont. (Gini = 0.324) and least equality in Lethbridge, Alta. (0.709).

Street tree equality

Are unequal distributions of street trees unfairly burdening marginalized populations? In other words, are the uneven distributions creating inequities between neighbourhoods with different socio-demographics? Such inequities are common in many U.S. cities,[2] with lower income households and racial minorities often living in neighbourhoods with relatively low tree canopy cover.

Conway and Martin explore the possibility of inequities using the Canadian Index of Multiple Deprivation, developed by Statistics Canada.[3] The index includes four measures:

• Residential instability, which measures fluctuations in neighbourhood residents,
• Economic dependency, which addresses a population’s reliance on the workforce,
• Ethno-cultural composition, which measures the immigrant and visible minority populations, and
• Situational vulnerability, which describes additional demographic characteristics such as education levels and home value.

Next steps

While identifying uneven distributions and inequities within street trees or across the urban forest is an important first step, simply planting more trees in underserved areas will not necessarily achieve a just outcome. Rather, recognitional justice concerns need to be addressed, which acknowledges that different communities have diverse needs and expectations. With funding from the School of Cities UCG Catalyst Grant, Tenley Conway and PhD student Isaac Mendita are working in partnership with the City of Toronto Urban Forestry division and local tree planting NGOs to engage in community mapping in two marginalized communities identified as having below average tree cover. Through this project we hope to learn where community members do and do not want trees planted, along with desired tree characteristics. Findings will be shared with community leaders and research partners to develop an approach that incorporates communities’ needs and helps guide future tree planting efforts.

Related publications and resources

• Martin, A.J.F., A. Fleming, & T.M. Conway, "Distributional inequities in tree density, size, and species diversity in 32 Canadian cities," npj Urban Sustainability 5, no. 18 (2025), DOI
• Martin, A.J.F. & T.M. Conway, "Using the Gini Index to quantify urban green inequality: A systematic review and recommended reporting standards," Landscape and Urban Planning 254, no. 105231 (2025), DOI
• Martin, A.J.F., L.G. Olson, E.S. Bacon, et al., "A biogeographical analysis of taxonomic diversity and native species dominance in 32 Canadian street tree populations," Urban Ecosystems 28, no. 158 (2025), DOI
• Martin, A.J.F., L.G. Olson, E.S. Bacon, et al., "The structural diversity of Canada's urban forests: A national summary and an analysis of street tree size across ecozones, city sizes, and within cities," Journal of Forestry 123, 217–240 (2025), DOI
• Canadian Institute of Forestry/Institut forestier du Canada. "Open Urban Forests." Link