Montreal’s urban wood recovery program may be the largest in the world. In 2019, the city felled 18,000 of its one million ash trees due to the Emerald ash borer, an invasive insect. Many were chipped or left to decompose, but about 2,000 tons worth from the city’s large parks were turned into lumber, pulp and paper. The social enterprise Centre de valorisation du bois urban (urban wood valorisation center, or CVBU), sent about a hundred trucks to pick up the logs and get them to local mills, designers, and fabricators. Some 200,000 board feet of lumber—twice the amount covering the Brooklyn Bridge Promenade—became chairs, desks, flooring, toboggans, and skating rink boards for the City and others.

Collaboration between Montreal, CVBU, and design/fabrication group Bois Public returns urban tree removals to the community as useful objects. Video credit: City of Montreal & Bois Public

For Patrick Piché, the founder and currently sole employee of CVBU, this impressive achievement is only the start of a much bigger opportunity for regional cities to use this wood in their own backyard—if they would take it. According to Piché, bringing cities aboard has proved to be the greatest challenge. CVBU recovers ash trees from five municipalities, including Montreal, the largest source by far. Dozens more could get involved, but most conversations about felled trees focus on the fastest, cheapest way to get rid of them. For Montreal alone, ash trees are a multi-million-dollar problem.

It's a story emblematic of the challenges and opportunities on the doorstep of cities around the world. Cities use huge amounts of wood, which is increasingly touted as a renewable material benefitting the climate, environment, and society. Trees create biodiverse habitats, filter water, provide shade, and pull CO2 out of the atmosphere. To realize the benefits cities must use wood that respects these values. An urban wood program, for instance, saves valuable wood from the chipper, gives it its highest and best use, and keeps carbon out of the atmosphere.

Of course, as practical and poetic as it is, urban wood alone is not enough to meet city wood demands. That is why it is one of eight pathways in the Cities4Forests’ Sustainable Wood for Cities Guide, designed to help cities identify and evaluate sustainable wood sources in their mission-aligned projects. The digital platform lays out an array of currently available sourcing strategies that can help protect and conserve forests, support sustainable forest management, meet green building objectives, and build a resilient future in urban spaces and beyond.

This will be essential as cities reckon with growth and housing demands while reducing their carbon footprints. Los Angeles, for example, expects to build close to half a million new and affordable homes by 2029 to address its housing crisis. At the same time, as one of the C40 cities that led the Clean Construction Declaration to address GHG emissions in the construction sector, Los Angeles is committed to reducing embodied emissions by at least 50% for all new buildings and major retrofits by 2030.

As a low-carbon material compared with concrete or steel, wood can help, but it is not always obvious how. Is wood from certified forests the only option, and what if it’s not available? Is tropical timber, plantation timber, or old-growth timber ever a sustainable choice? What are the possible pathways by which wood can markedly reduce a project’s carbon footprint?

The Sustainable Wood for Cities Guide provides a high-level, qualitative framework for answering these questions, and was designed for cities in view of their agency and objectives. It is a product of a multi-year collaboration between procurement specialists, foresters, urban planners, project managers, ecologists, and conservationists, that unearthed key considerations.

The result is the eight pathways, which can be used independently or layered together for even greater impact. The eight pathways are:

1. Forest certification

Through third-party audits of managed forests and chain of custody through the supply chain, adherence to standards of sustainable forest management is assured and can be communicated to the public. FSC and PEFC are best known internationally.

2. Social forestry

In social forestry, the purchase of wood and other forest products sustains community-based forest stewardship institutions, which are often vital to local livelihoods. At its best, social forestry offers high sustainability benefits per unit of wood because it prioritizes long-term resource conservation. Exemplary enterprises include Cities4Forests’ Partner Forests.

3. Species and grade selection

Over reliance on a few high-demand wood species creates unneeded waste and forest degradation. More nuanced and intentional selection of wood species and grade—including hurricane-downed or beetle-killed “calamity wood,” shorter lengths, and character grades—can vastly reduce the pressure on forests while meeting increasing demand. An excellent example of a company growing opportunities for lesser-known regional species is Brooklyn-based wood products manufacturer Tri-Lox.

4. Strategic geography

Strategic geography describes when wood is sourced from jurisdictions pursuing specific sustainability outcomes, such as enforcing laws against illegal logging. Wood purchases that use strategic geography can reward regional best practices in sustainable forest management and build their recognition.

5. Local and urban wood

Cities fell trees and plant new ones every year. Tapping this wood source can save trees from the chipper, store carbon, create skilled jobs, and return prized, useful products to the community. The Urban Wood Network and the work of urban lumber advocate David Barmon are examples of this in action, as they envision a future where cities can intentionally grow trees for lumber.

6. Re-use and long life

Wood stores carbon for as long as the material is intact. Projects that use reclaimed wood or design for eventual disassembly and reuse capture and extend this benefit. Baltimore’s Brick & Board, Vancouver’s Unbuilders, Portland’s Good Wood and many others are demonstrating the creative possibilities of this approach.

7. High-efficiency production

Turning trees into useful building components requires tools and processes that come with tradeoffs among cost, speed, and convenience. As consumers improve their understanding of the life cycle and carbon impacts of wood products, they can expect producers to respond with improved harvesting and manufacturing processes that minimize wood waste and the associated carbon emissions.

8. Net carbon accounting and life-cycle analysis

This pathway ties it all together, as it involves a comprehensive approach to calculating the net carbon profile for a chosen wood package. Land use, forestry practices, production, transportation and manufacturing would all factor into this approach, allowing a fair comparison between wood and competing materials within a building life cycle analysis.

Putting wood to work for sustainability objectives

Together, the pathways can provide a common ground for all stakeholders to procure wood in a way that supports both cities and forests. The City of Portland, for example, is undertaking a sustainable wood pilot that connects wood to broader social economic objectives. Working with local environmental consultancy Sustainable Northwest, the city is using the Sustainable Wood for Cities platform to test-drive wood-package assessments for city projects and inform the writing of procurement contracts. In addition, the pilot is looking to use wood’s storytelling power for good, said Sustainable Procurement Program Manager Stacey Foreman. For example, she sees opportunities for regionally sourced timber to elevate Indigenous-managed forestry, and for re-used and local wood to highlight minority-owned business and heritage.

Meanwhile, Vancouver is engaging certified wood, net carbon accounting and strategic geography to address its need to grow. The city faces a housing crisis, but is also committed to reducing its embodied carbon from construction by 40% by 2030. At the same time, the province is touting mass timber as one way to move British Columbia’s forestry from reliance on high-volume extraction to high-value production. The upshot for Vancouver, said city Green Building Engineer Patrick Enright, is an opportunity to build low carbon. Upcoming by-laws shaped by Sustainable Wood for Cities will phase in requirements to source from either certified or Indigenous-managed forests. Importantly, most of the province’s commercial forests will qualify for use so that Vancouver will be an important market for high-value, regionally-produced timber.

Next steps for Montreal and cities everywhere

What city will be next to lead on sustainable wood? Will Montreal run with its head start? With similar or increasing numbers of ash trees to be felled in the years ahead, urban wood is well under development. With more support, CVBU could bring aboard the more than 80 municipalities of the Greater Montreal Area. Additional pathways could leapfrog the city even further ahead. A recent announcement in Montreal that all new construction must be zero emission beginning in 2025 would seem to demand a new policy on sustainable wood in construction. In a rapidly urbanizing world faced with unprecedented environmental challenges, the importance of forests to cities, and the knowledge and skill to use them wisely, can’t be overstated.