Tree Planting Prioritization Tool

Beginning in 2007, the Region of Peel in Ontario started working on a tool to strategically target its tree planting work resulting a more efficient means of combating the effects of climate change and the urban heat island, especially for citizens with a lower socioeconomic well-being. Peel Region is a regional municipal government that has jurisdiction in the Western reaches of the Greater Toronto Area and includes the communities of Mississauga, Brampton, and Caledon. This work was conducted in collaboration with local municipalities and Conservation Authorities. The end result was the production of a GIS tool that allowed for the Region of Peel and its partners to make more informed decisions regarding tree planting in the area, increasing the benefits to health and well-being that such vegetation provides.

Understanding and Assessing Impacts

Trees are a simple and effective means of combating many of the hazards that are created or exacerbated by climate change. Most commonly, they are cited as an effective means of battling the urban heat island effect, but tree also provide benefits towards reducing air pollution and stormwater discharge as well as increasing property values and improving mental health. Tree mortality rates are, unfortunately, increasing over time as pests and diseases such as the emerald ash borer, combined with changing weather patterns due to climate change, are damaging the urban canopy. The rapid population growth in Peel Region, and its primarily suburban development pattern, further complicate the process of tree planting as development pressures threaten historic greenspaces that sheltered much of the urban canopy. Many of the low canopy areas in the Region are also home to recent immigrants, recent refugees, and citizens that are socially and economically vulnerable. Additionally, municipal governments have many important matters to spend their limited funds on and, as a result, tree planting programs often operate on rather limited budgets. This adds extra pressure to ensure that what tree planting programs do exist are managed effectively and deliver the most benefits for the resources invested in them. It is this complicated environment that gave rise to the demand for a program that allows the regional government to make the best decisions possible regarding tree planting.

Identifying Actions

In Peel Region, most of the actual work of planting and maintaining the urban forest canopy is done by the local municipalities of Mississauga, Brampton, and Caledon. Because of this, the Region of Peel knew immediately that they would have to work closely alongside these entities in order to ensure the successful planning and implementation of their new program. Beginning in 2007, the Region of Peel began collaborating both with the abovementioned municipalities as well as two local conservation authorities, the Toronto and Region Conservation Authority (TRCA) and the Credit Valley Conservation Authority (CVCA). After four years of collaboration, the Peel Region published the Peel Region Urban Forest Strategy in 2011. Following the publication of this guidance document, officials in all concerned entities began the discussion of how best to implement the plans laid out therein. It soon became clear that there was a need for a science-based planning tool to help environmental stewards, planners and urban foresters maximize the efficacy of their tree-planting efforts. A multi-disciplinary team, comprised of professionals in the fields of parks, forestry, environmental education and stewardship, public health, planning, transportation, and human services was then assembled to provide technical support and help guide the development of the tree planting tool.


The development of the tool proceeded along a three-step process. The first step was to conduct a thorough review of the scientific literature and identify the sustainability benefits provided by the urban tree canopy. The results of this work were then grouped into eight distinct categories of benefit and further consolidated into three sustainability themes. The second step involved the Identification of criteria to apply to the sustainability themes. For this phase, the project team identified potential target benefits and reviewed data sets at various scales to spatially define each of the eight categories of benefits. This work involved identifying specific criteria for data sets such as locating the spatial extent that these benefits would be best realized in. Each category was given a set of 12 targeted benefits. The third and final step centred on the creation of the GIS tool itself, incorporating all of the identified benefits from the previous two steps. These benefits, their spatial extent, the selective weighting of benefit categories, and more were all folded into the program alongside detailed geographic information such as land cover and possible planting areas. The end result of this process is a flexible GIS tool that enables the user to prioritize tree planting at different geographic scales with the smallest available scale being that of the dissemination area.

Next Step

As a testament to its flexibility, the tool is being used for different purposes by the different partnering organizations. For example, the Credit Valley Conservation Authority intends to use the tool to guide outreach and restoration efforts on public and private lands in parts of the watershed that are being developed. Conversely, the Town of Caledon plans to utilize the tool for the purposes of identifying gaps in the tree canopy on municipal lands where planting space is already available and planting activities could be launched in the short term.