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Best practices and strategies for the urban forest

An executive summary of Peel Region’s first Planting and Management Program guide

The following content is an executive summary of Peel Region's Best Practices and Strategies for the Urban Forest. It provides an overview of best practices for managing Peel Region’s urban forest (primarily for street and park trees). Contact Heather Hewitt if you would like to access the full set of reports.


Climate change has already begun and will continue to reduce liveability. It will also keep threatening human health and the biophysical systems we depend on. This is especially true in urban areas where heat and other environmental stressors are more intensified.

Trees have the unique ability to moderate some of these threats by cooling and filtering the air as they live and grow. However, while climate change has increased the need for more healthy and mature trees in urban spaces, it has also made it more difficult for trees to survive in these already harsh settings.

Therefore, sustaining and enhancing street and park tree populations, and the urban forest as a whole, requires a sustained commitment to providing the best possible growing conditions for trees and embracing a tree-friendly culture not just among those caring for these trees, but throughout the community.

Taking a climate-sensitive approach to urban forest planning and management is not complicated. It means continuing to implement many of the same best practices that practitioners already know, with more emphasis on diversification, integrated planning, and collaborative design.

The focus should be on providing space and "habitats" for the trees, even on a small scale, that let them do more than just survive.

This executive summary includes:

Other information

Peel Region and its municipal and agency partners have been working together through the Peel Urban Forest Working Group. Since 2007, they’ve identified and implemented strategies to protect and enhance Peel's urban forest and to help local communities adapt to climate change.

These partners, through the Peel Climate Change Partnership (PCCP), continue to prioritize urban forestry a priority action area because it contributes to both climate change mitigation and adaptation.

The PCCP specifically identified increasing the number of healthy trees in priority areas as one of its 3 strategies for addressing climate change challenges.

The Peel Climate Change Master Plan (2020-2030) has a goal to "protect and increase green infrastructure throughout Peel" with tree planting and a management program for new and existing trees as key actions to achieve this objective. We need the best growing conditions for trees

The Peel Region urban forest best practice guides

The Peel Region urban forest best practice guides are intended to help support and achieve these objectives. The guides are primarily intended for Peel’s urban areas.

  • Guide 1: Best practices guide for urban forest planning in Peel
  • Guide 2: Urban forest management best practices guide for Peel
  • Guide 3: Guide for tree and shrub standards and specifications for regional roads in Peel
  • Guide 4: Potential tree species for Peel in a climate change context
  • Guide 5: Working with trees: best practices for a resilient future

A climate change planning and adaptation framework was developed for Peel’s urban forest to help implement best management practices.

The framework is intended to be flexible and responsive to new information and changing conditions. It can be applied at the jurisdiction-wide scale and at the site-specific scale.

Adaptive management

Adaptive management is learning while doing, monitoring progress, and being prepared to adjust as required.

The circular structure of this framework embeds the principle of adaptive management. To learn from successes and mistakes, managers must:

  • Strategically and repeatedly document actions taken.
  • Track the results of these actions.
  • Assess the results in achieving the intended outcomes.
  • (Depending on the assessment) continue or revise the approach.

Take action now

The planet is on a "worst case" scenario trajectory for climate change (IPCC 2018). The need to take actions to protect and enhance the urban forest has never been more urgent.

Seek "best bets, no regrets" actions

Choose actions that can contribute to climate change adaptation or mitigation but are unlikely to have negative impacts to the urban forest if they fail. This minimizes the risks associated with the uncertainty of climate change impacts.

Right tree, right place

Know the range of conditions that certain tree species are naturally adapted to. Work to match or provide as many of these conditions as possible when selecting establishment sites in cities.

Plan to adapt

We still can't say for sure how climate change will impact the urban forest and how the urban forest will respond. So being able to collect and to respond to new information will be key.

Be proactive and be prepared

Municipalities must actively plan and prepare for more frequent extreme events and impacts of climate change that could negatively impact the urban forest. The time and effort of being proactive will save money and resources when we need to respond.

Trees can help communities adapt to climate change by providing a range of services and benefits. However, they're also vulnerable to environmental stressors, many of which are exacerbated by climate change.

Global average temperatures could rise as much as 2°C by the 2050's and as much as 5°C from current levels under the "worst case" scenario (also known as RCP8.5), which is the current trajectory. The projected climate in the 2050's under the RCP8.5 scenario, informed the work for this project.

Potential impacts on trees

Based on these projections and current science, some of the potential impacts on trees and risks to the urban forest include:

  • Limited tree growth and increased mortality.
  • Flowering that is uneven or failed (or both), which threatens seed production.
  • Increased susceptibility to pests and diseases, and
  • Potential loss of certain species or genera.

The planning and adaptation framework and the recommended best management practices are intended to:

  • Promote actions that both reduce and manage exposure to urban and climate change stressors, and
  • Increase the adaptive capacity of urban trees to respond to such stressors.

A fundamental best practice is having a good understanding of the state of the urban forest, particularly given the uncertainties in predicting urban forest responses to climate change.

Understanding the urban forest is key

Trees are a diverse group of organisms with variable tolerances and sensitivities to environmental conditions and stressors. Therefore, having a good understanding of the trees themselves (e.g., species, size, condition), and where they’re being planted or are already growing, is key to supporting their successful establishment and maintaining their health.

A good understanding of the urban forest is rooted in a comprehensive inventory of municipal tree assets that is maintained and can be shared and complemented by a jurisdiction-wide urban forest monitoring program that leverages the power of remote sensing.

This understanding can inform strategic decision-making for where and how best to invest in establishing additional trees and maintaining the existing trees. It should also be supplemented by a willingness and ability to assess the site-specific context and conditions before investing in new plantings. (More detailed guidance is provided in Guide 2).

The following best practices are key to building urban forest resilience in a changing climate and enhancing social and environmental outcomes.

Value the urban forest as an asset

Incorporate the urban forest into municipal asset management frameworks.

This ensures that municipality-owned trees are recognized for the services they provide and as assets requiring targeted maintenance and monitoring to sustain those services.

Invest strategically

Prioritize investments in actions that increase the resilience of the urban forest to current and anticipated stressors. This will maximize returns in a climate change context.

For example, up-front investment in proper street and park tree species selection, establishment, and good growing conditions can minimize large expenditures as trees mature.

Have a strategic plan

Develop a strategic Urban Forest Management Plan and integrate it with other jurisdiction-wide plans to protect, maintain, and establish trees in effective and locally appropriate ways.

These plans can also help direct tree-related risk management and provide a framework for adaptive responses to new information and changing conditions.

Enhance tree and urban forest diversity

Incorporate structural, functional, and genetic diversity of all types and at all scales into the urban forest system to build resilience in the face of climate change.

This should include the careful and gradual introduction of suitable species with ranges slightly south of the target planting area.

Plan with equity in mind

Improve the equitable distribution, availability, and quality of public greenspaces and tree cover across the jurisdiction.

This may include targeting areas not immediately suitable for trees that require an initial investment and collaborative planning and design to create suitable space above and below-ground.

Take an integrated approach to planning

Align other municipal strategic plans with urban forest goals and embed urban forest objectives in all levels of planning.

This will instill a common vision that includes trees as part of the solution to climate change challenges.

Take an integrated approach to design

Develop an integrated approach at the site-level to ensure implementation of street and park tree-friendly design through the cooperation, coordination, and expertise of multiple disciplines (for example, urban foresters or arborists (or both), planners, engineers, landscape architects, and architects).

Seek climate-positive outcomes

Actively seek opportunities to moderate the urban heat island effect where it is felt by the most vulnerable people.

Investing in planting trees that can reach maturity in built areas can provide significant cooling along with other services and benefits such as air quality improvements and wind breaks.

Foster a tree-friendly culture.

Develop partnerships with other public and private sector landowners to create opportunities for protecting and expanding tree cover on lands not under municipal ownership or management.

Be proactive and prepared

Invest in proactive urban forest management to reduce the negative impacts of an urgent situation like an ice storm or a destructive pest. Have preparations in place, such as emergency plans and funds.

Climate change adaptation research in Canada has shown that every dollar invested in being prepared can save between $4 and $6 dollars required in reactive emergency responses.

Climate change has introduced a much greater degree of uncertainty into weather patterns.

These changes are expected to negatively impact both the people and the trees in our communities. This makes protecting and sustaining trees in the urban forest challenging, particularly in the most built-up areas.

However, many of these challenges can be overcome with careful and collaborative planning and management undertaken at various scales with input from knowledgeable professionals.

The 10 urban forest best practices should be used to inform municipal strategic directions. Urban forests provide invaluable services and co-benefits that contribute directly to community health and well-being.

Investing proactively in the urban forest to help make it more resilient to climate change is one of the most cost-effective actions municipalities and their partners can take to help communities adapt to climate change.

  • Masson-Delmotte, V., P. Zhai, H. O. Pörtner, D. Roberts, J. Skea, P.R. Shukla, A. Pirani, W, Auld, H., H. Switzman, N. Comer, S. Eng, S. Hazen and G. Milner. 2016. Climate Trends and Future Projections in the Region of Peel. Ontario Climate Consortium, Toronto, ON.
  • Tu, C., G. Milner, D. Lawrie, N. Shrestha and S. Hazen. 2017. Natural Systems Vulnerability to Climate Change in Peel Region. Technical Report. Toronto, Ontario: Toronto and Region Conservation Authority and Ontario Climate Consortium Secretariat.

This summary report was prepared for Peel Region and its partners as part of the Peel Region Urban Forest Best Practice Guides project.

These guides have been developed collaboratively with input and guidance from members of the Project Team, Peel Urban Forest Working Group, Peel Climate Change Partnership, and other urban forestry and arboriculture professionals.

Specific thanks are extended to:

  • Peel Region: Heather Hewitt, Mark Pajot, Samantha Paquette, Liz Brock, Christine Tu, Chris Despins, Danielle Gnoyke, Mark Head
  • City of Mississauga: Paul Tripodo, John MacKinnon, Sarah Piett, Scott McLeod
  • City of Brampton: Michael Hoy, John Allison, Brian McKelvey, Natalia Fleishman, Zoe Milligan
  • Town of Caledon: Nick Pirzas, Christina Guido
  • Credit Valley Conservation (CVC): Yvette Roy, Aaron Day, Melanie Kramer, Christine Wilson, Joe Pearson, Lisa Riederer, Dawn Renfrew, Laura Timms, Kata Bavrlic, Aviva Patel, Scott Sampson
  • Toronto and Region Conservation Authority (TRCA): Michelle Sawka, Meaghan Eastwood, Ryan Stephenson, Mark Funk, Courtney Den Elzen, Jackie Hamilton, Jackie De Santis, Sharon Lam, Marketing and Communications Department

The consulting team for this project has been led by Margot Ursic of Beacon Environmental Limited with support from Steve Colombo of Ecoview Consulting Limited and Jana Joyce of the MBTW Group.

This project would not have been possible without the research, writing and engagement support provided by Ash Baron, Todd Smith, Dan Westerhof, Stephan Crispin, Natasha Collins, Anna Cunningham and Sarah Zicca of Beacon as well as Mike Hukezalie of MBTW.

While every attempt has been made to provide current information in an accurate manner, the authors take responsibility for any errors or omissions.