Growing Forests in a City

In 2012, the City of Montreal created one of the most ambitious municipal tree planting plans in Canada, aiming to increase its tree cover to 25% by 2025, plus an additional 500,000 trees by 2030. The Plan d’Action Forêt Urbaine (PAFU) set out a 10-year budget and tree planting targets for each of Montreal’s boroughs and other municipalities on the island. As the city and its boroughs organized tree planting on public land, it partnered with SOVERDI, a Montreal urban greening ENGO, to reach out to and incentivize private landowners to contribute to the plan. SOVERDI created the Alliance Forêt Urbaine, a coalition of ENGOs dedicated to increasing Montreal’s canopy cover. With funding from the City, the Alliance was able to leverage more than $3.7 million in additional private investments and plant 55,000 trees on private land since 2015.

Urban forests can help cities adapt to a changing climate. They can offer refuge in heatwaves, limit flooding, filter air pollution, and provide wildlife corridors. Green spaces also offer many much-needed mental and physical health benefits, sequester greenhouse gas emissions and increase property values.

Understanding and Assessing Impacts

Increasing summertime temperatures and extended heatwave events, such as the 2018 heatwave, demonstrated that particular communities are more vulnerable to heat-related illness and death. The people who died during the heatwave were generally low-income, elderly, and living alone. In Montreal, as in many other urban centres, tree cover is higher in historically wealthier areas. Low-income areas, typically with higher proportions of visible minorities and lower education and income levels, generally experience less tree coverage. Increased tree cover in these areas would help cool the air and provide a refuge during heatwaves, and potentially save lives.

Surrounded by rivers and heavily urbanized, Montreal is prone to inland flooding. As precipitation increases with a changing climate, people and infrastructure will face increasing risk of flash floods and overflowing rivers. Preserving and enhancing natural habitats in and around cities contributes to reducing these risks by allowing water to return to the ground.

Forests do not have to be big to deliver big value. Their value continues to grow as cities seek to address converging challenges of population growth, climate change, and biodiversity loss. The benefits of urban forests include:

  • Capture greenhouse gases
  • Lower air temperatures
  • Decreased flood risk
  • Increased biodiversity
  • Cleaner air
  • Food security
  • Improved general health

Recognizing the importance of its urban forest to mitigate the impacts of climate change, the City of Montreal mapped its tree canopy index, the ratio of tree crowns or groups of trees (the canopy) to the total urban area, using aerial photography from June 2007 for every municipality on the island. The initial index was set at 20.3 percent of tree canopy and was the basis for the Plan d’Action Forêt Urbaine that followed, setting tree planting goals by land use for each of the boroughs and cities.

Identifying Actions

Montreal’s Plan de développement durable de la collectivité montréalaise 2010-2015 originally set urban tree canopy targets that aim to increase tree coverage from 20 per cent to 25 per cent by 2025. The 2012 Plan d’action forêt urbaine (PAFU) followed shortly after paving the way with targets for each municipality and a 10-year budget. In its recent climate plan, the city further committed to plant 500,000 trees by 2030. This is one of the most ambitious goals in the country, considering the timeline and population, as well as industry and commercial density. A study by Ziter et al. (2019), for example, finds that tree cover needs to approach 40 per cent in order to achieve significant cooling benefits.

Aside from quantity planted, the quality of the trees also matters. The location of trees, the type of trees, planting conditions, and work done to maintain and protect the health of trees will determine the magnitude of benefits realized as benefits increase along with tree growth. It is generally more expensive and challenging to plant trees in areas that have a high concentration of industry and transport infrastructure, given that surfaces are often covered with pavement and asphalt. Greater investment is usually justified in these areas, however, with higher societal benefits resulting.

– Identified barriers hindering the expansion of urban forests are:

  • Unaccounted benefits that make a strong business case to invest in urban forest
  • Cost and inadequate municipal financing and fiscal schemes
  • Lack of readily available space
  • Lack of incentives for private investment
  • Uneven human capacity and financial resources across the different boroughs
  • Quality of supply of trees to match tree planting ambitions of the City
  • Uneven and poor data collection to better understand state and diversity of the urban forest
  • Harsh urban conditions as well as pests and diseases

The Emerald Ash Borer has slowed Montreal’s efforts to increase its tree canopy. The insect put 20 per cent of Montreal’s urban forest at risk, potentially setting back tree cover by 2 to 3 points of percentage over 15 years.

Data collection and evaluation have been hindered by a lack of monitoring capacity. Aerial and satellite photography cannot provide the same detail as ground level measurements. Understanding the type of tree, size, height, and location can allow for more precise and detailed evaluations of tree biomass and ecosystem services like carbon storage, water retention, and air pollution abatement. Initiatives in certain Montreal boroughs are taking place to measure and identify individual trees.


The city, alongside its partner SOVERDI, created the Alliance Forêt Urbaine, a coalition of ENGOs dedicated to increasing Montreal’s canopy cover on private land. In addition to investments for public trees, the city of Montreal provided more than $4.2M to SOVERDI and the alliance through grant programs from 2015 to 2019. Together, these ENGOs have planted close to 55,000 trees on privately owned land in Montreal’s boroughs and cities since 2015.

With the funds provided by the city, the ENGOs were able to leverage more than $3.7M in private investments from project proponents through targeted planting campaigns for institutional, commercial, and industrial landowners as well as residents. Partnerships with important stakeholders, dubbed leaders of the urban forest, like CN, Port de Montréal, la Caisse de dépôt et placement du Québec (CDPQ) and Hydro-Québec also contributed to these investments.

Financing tree planting projects can be challenging due to restrictions on municipal accounting. Under the Generally Accepted Accounting Principles (GAAP), trees are considered operating expenses as opposed to capital investments. This prevents cities from financing (or amortizing) the upfront cost of planting trees. Recognizing urban forests as green infrastructure, on the other hand, would provide a basis for capital investment. The Permanent Commission on Water, Environment, Sustainable Development and Parks recommended that the urban forest be recognized as a green infrastructure capital investment, a recommendation that the executive committee implemented soon after.

Cost-effective planting strategies also require steady sources of new trees. Montreal has had its own tree nursery since 1948. It is the biggest in Canada, with around 80,000 trees at different stages of development. It provides Montreal boroughs with about a third of trees planted annually. It has around 140 different species and is seeking to increase diversity; however, the city is being challenged to reach its targets.

To further limit flooding risks and protect important natural areas, the city acquired land covering 175 hectares, with the help of $50M from the federal disaster mitigation and adaptation fund (DMAF) to create the Grand parc de l’Ouest.

Outcomes and Monitoring Process

The city of Montreal is on track for reaching its goal, as the urban canopy index was recently estimated at 23 per cent. SOVERDI and partners are also well on their way to planting 20,000 trees per year for years to come.

Montreal’s Grand parc de l’Ouest, covering 3,000 hectares, is projected to become Canada’s largest municipal natural park. The area includes forest, agricultural land and wetland, supporting biodiversity, protecting natural infrastructure that limits flooding, and providing a range of recreational opportunities.

Potential co-benefits exist between increasing tree canopy and carbon offset markets to finance urban forests. Offset markets – where businesses or individuals offset their greenhouse gas emissions by purchasing credits generated from emission removal or reduction efforts – offer a potential source of finance to expand urban tree cover. Urban trees could yield greater overall societal benefits than trees in outlying areas as they provide multiple benefits to larger populations. Despite this opportunity, uptake of these types of programs has had limited success due to a number of factors.

After the initial years of the action plan, the city lowered annual tree planting objectives in grant agreements with SOVERDI and increased per-tree budgets to ensure the necessary care and monitoring of each tree planted.

Next Steps

The city and senior levels of government can continue to aid in the expansion of urban forests in Montreal by:

  • Designing investment programs and offset frameworks to capture a wider range of societal and environmental benefits that balance the risks associated with non-permanent CO2 sequestration.
  • Require developers and property owners to invest in trees and sustainable maintenance practices
  • Finance capital and operating costs to keep trees alive in the face of disease and a changing climate
  • Implement stringent regulations to protect existing trees and provide incentives for private landowners to plant and care for new trees
  • Support strong supply chains to meet demand and help existing and prospective nurseries
  • Invest in research and data collection