The equity of urban forest change and frequency in Toronto, ON

Abstract

Urban forests provide a myriad of social, environmental, and economic benefits that help make cities desirable and safe places to live. However, despite their importance, urban forests are often inequitably distributed, with marginalized populations having disproportionately low access to them and their associated benefits. For this reason, understanding the distribution and change of urban forests is key to achieving their equitable presence and management. Though urban forest equity is becoming a well researched topic, few studies address the equity of urban forest change and most existing equity studies assess only canopy cover. This study addresses these gaps by examining the relationship between changes in Toronto’s urban forest over a ten-year period and its frequency with four indicators of population marginalization. Diameter growth rate, mortality rate, and establishment rate were used to quantify change, while basal area per hectare and stems per hectare were used to quantify frequency. The indicators of marginalization used in this study were residential instability, economic dependency, ethnocultural composition and situational vulnerability, from the Canadian Index of Multiple Deprivation. Bivariate correlation, multiple linear regression, and geographically weighted regression were used to determine if there was a relationship between each urban forest variable and each indicator of marginalization. Bivariate cluster analysis was also used to identify areas in Toronto with the highest occurrences of urban forest inequity. Significant correlations are found between several indicators of marginalization with diameter growth rates, establishment rates, and both frequency measures. Furthermore, areas in Toronto with the highest establishment rates were also the areas with the highest tree frequency before this change analysis. Ultimately, this study suggests that changes in Toronto’s urban forest are not helping to resolve its inequity, but reveals that understanding urban forest change can provide insights into potential perpetrators of existing inequities that may help cities address them.