By Jacob Dunn, Associate Principal, LEED AP® Homes

As architects, we’re often too far removed from the relationship between the materials we specify and their impact on the environment. Given the ever-shortening timeframe we have to meaningfully effect climate change, we must start addressing the impact of building materials immediately. For instance, 11% of global emissions are from the embodied carbon in building construction, roughly 3,729,000 metric tons of CO2 per year. We know that concrete and steel are fairly carbon intensive building materials and that alternatives like wood can offer a lower embodied carbon footprint and other ecological benefits.

However, it’s not as simple as just choosing wood. Like with any material, the use of wood has a spectrum of sustainability that should be addressed to keep pushing the industry toward a more sustainable future. This is particularly important for wood as its ecological and climate impact can vary greatly depending on the species, product type, and perhaps most critically—how we manage the forest where the wood comes from.

Sustainably Managed Forests and Ecological Forestry
Sustainable harvesting, responsibly managed forests, ecological forestry, sustainable forestry—so many terms exist, and each are appropriate depending on the type of forestry at play. To simplify things, I like to use the term sustainably managed forests, as it implies a balance between managing forests for economic productivity and ecological benefit. Underpinning these terms are harvest practices that aim for ecological forestry.

What is ecological forestry? As its most basic level, it’s forestry that mimics natural patterns of disturbance and regeneration. Like with most natural systems, this boils down to one thing: diversity. Healthy forests have a diversity of horizontal structure across the landscape (think tree spacing and understory variety), diversity of vertical structure up the tree strata (multiple ages of trees with different canopy development), and species diversity (monocultures are more susceptible to shocks). This diversity is key to everything: from enhancing the forest’s wildfire resilience to unlocking the water filtration benefits so powerful that many municipalities follow these principles on forests whose watersheds provide drinking water to cities.

The wildfires that devastate the West Coast now annually are an urgent reminder of the vulnerability of our forest land and our communities. Ecological forestry can address this in two ways. First, increasing forest health restores the land’s natural fire resilience to mitigate the magnitude of fire impacts. Second, increasing carbon stocks helps mitigate climate change and reduces the conditions that exacerbate the probability of fires throughout the year. It’s important to note that while the principles of ecological forestry may not directly lead to more carbon sequestered on the landscape, many of its tenants do overlap with climate friendly forestry.

From specific harvesting perspective, the following silvicultural practices support a working forest, one managed for timber production and other values. Following these practices can lead to more diversity on the landscape in comparison to tree plantations and the other intensive forms of industrial forestry.

• Longer harvest rotation times: Increasing harvest times from the approximate industry average of 40 years to 60-plus years allows the forest to mature and develop characteristics key to ecological system services before the next harvest. This can also help to maximize carbon storage in the forest.
• Bigger riparian buffers: Limiting or eliminating harvest activities around streams minimizes erosion and protects waterways for fish and people alike.
• Increasing retention requirements: Retention can be thought of as the amount of trees left behind during a harvest. This allows for some of the trees to develop into even more mature stages and helps maintain a continuity of ecological function during regeneration post-harvest.
• Maintaining a diversity of tree species: This helps ensure horizontal and vertical structural diversity while hedging against risks that target specific species.
• Alternative silvicultural practices: There are good ways and bad ways to clear-cut a forest. There are also a multitude of other harvesting strategies including shelterwood, single tree selection, uneven-aged managed, and patch cutting, that all have different impacts on diversity, structure, and timber output. For a primer on the details of each, check out this article.

Forest to Frame: Tracking Wood’s Origin
Once we know what a more sustainably managed forest entails, we can better understand how to support those forests with our projects. We currently have two primary options, which are not necessarily mutually exclusive: utilize third party certifications like the Forest Stewardship Council or directly target landowners we know are utilizing sustainable forest management. The latter warrants some further discussion around the idea of tracking wood back to its forest of origin.

A familiar analogy for this approach is the “Farm to Table” movement for food, or as I’ve heard it called for forestry: “Forest to Frame.” There are key differences between the two types of supply chains, but the end goal is the same – to know who you’re supporting and how they’re creating their product.

Unfortunately, the many layers of the wood supply chain and its emphasis on efficiency make it difficult to track origin. This exacerbates the obfuscation between our design choices and their impact, or between the wood in our buildings and the way the wood was harvested. Without knowing exactly where our wood comes from, we can only assume it came from wide variety of sources that exist on a spectrum of sustainable harvesting and economic impact.

We’re lucky that in the Pacific Northwest there are so many landowners responsibly managing one of the region’s most precious natural resources. Our goal is to connect our buildings back to the land and celebrate these landowners who are going above and beyond what’s required. Transparency in the wood supply chain gives these landowners a way to differentiate themselves in a market encroached upon by overseas timber industries with more technologically advanced manufacturing processes and thus cheaper products. If we can target these landowners through our procurement process, we can hopefully increase the demand and direct recognition for this type of forestry, ultimately leading to more landowners managing their forests this way.

The key question is how we achieve this supply chain transparency and track our products back to their forest of origin. It’s something we’re currently piloting on projects and look forward to sharing our findings soon.

What’s Next
As the mass timber industry grows, it brings many opportunities to design more beautiful spaces, more economically efficient structures, and solve for a host of climate solutions. Here in the Pacific Northwest, we have a special connection to our forests for both their beauty and the economic value they bring to both urban and rural areas.

As architects, we’re obligated to educate ourselves about the connections between the materials we specify and their supply chains. What’s at stake is the ability to utilize sustainable forest management to truly position mass timber as a climate solution, while uplifting small businesses and the health of rural communities. Mass timber can be a win-win, but only if we execute it thoughtfully within such a complex economic and ecological system. This post reminds me of my favorite quote from Richard Power’s The Overstory, “There are no individuals in a forest, no separable events.”