The Impact of Wood Use on North American Forests

Can specifying wood for buildings contribute to forest sustainability?
 
Sponsored by Think Wood
By Roxane Ward and Dave Patterson, RPF
 
1 AIA LU/HSW; 0.1 IACET CEU*; 1 AIBD P-CE; AAA 1 Structured Learning Hour; AANB 1 Hour of Core Learning; AAPEI 1 Structured Learning Hour; This course can be self-reported to the AIBC, as per their CE Guidelines.; MAA 1 Structured Learning Hour; NLAA 1 Hour of Core Learning; NSAA 1 Hour of Core Learning; NWTAA 1 Structured Learning Hour; OAA 1 Learning Hour; SAA 1 Hour of Core Learning

Learning Objectives:

  1. Evaluate the use of wood as a construction material in the context of long-term forest sustainability as well as attributes such as low embodied energy and light carbon footprint.
  2. Discuss forest sustainability measures such as biodiversity, soil and water quality, and harvest versus net growth.
  3. Examine the concept that using wood in buildings provides an incentive to landowners to keep forested lands forested instead of converting them to uses such as urban development.
  4. Compare the carbon benefits of an unmanaged forest versus a managed forest where timber is used for wood buildings.

This course is part of the Wood Structures Academy

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Ensuring Healthy Forest Growth

After planting new trees, foresters use a variety of practices to support and encourage healthy forest growth, including understory thinning as well as understory planting and weeding. These treatments are applied to sustain ecosystem health and function, improve stand quality, and produce desirable tree qualities that provide important economic and ecological values. They can also help to reduce the risk of wildfire in forests where previous fire prevention and other factors have resulted in an excess buildup of woody debris.

To control competing vegetation or brush, foresters use a variety of tools including chemical (e.g., herbicides), manual (e.g., saws and axes), and biological (e.g., sheep).

When properly used, herbicides can be an appropriate tool in a sustainably managed forest. In stands of pine and spruce, for example, pioneer plant species such as raspberry and trembling aspen thrive on disturbed sites with open growing conditions (i.e., following harvest), easily outcompeting newly planted seedlings for nutrients, light, and water. Similar to a garden, weeds that are not controlled will take over and prevent the growth of desired species.

According to the U.S. Environmental Protection Agency (EPA), commercial and government use of herbicides (which includes forestry) accounts for 4 percent of use nationwide, while home and garden use accounts for 5 percent, and the agricultural sector accounts for 91 percent.16

All pesticides applied in the United States must be registered with the EPA and carry federally approved labels describing permitted uses and appropriate protection measures. To be registered, pesticides must be tested for effects on humans and the environment, and applicators of pesticides on forest land must also comply with state laws. In Canada, the Pest Management Regulatory Agency (PMRA) of Health Canada reviews and regulates all pesticide use under the federal Pest Control Products Act. Such registration indicates that, based on extensive expert review of all available scientific evidence, registered products have no potential for significant effects on human or environmental health when used as directed.

Description of image.

Photo courtesy of Plum Creek©/Colin Hackley

Thinning treatments were used in this southern U.S. forest to support and encourage healthy growth.

IS THERE A NEED TO ‘GREEN’ THE FOREST SECTOR?

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Photo: Gary Darby Weyerhaeuser

“Forestry is the art and science of creating, using, and conserving forests. The forestry profession was a pioneer in developing techniques for sustainable management and, later, techniques for the multiple use of forests. More recently, broad holistic concepts such as ecosystem management and landscape management have been developed, tested, and applied. These are all elements of the sustainability and sustainable management of a wide variety of renewable resources. Although the term “sustainable forest management” is synonymous with “good forestry,” forestry and forest management are sometimes viewed as potentially damaging to the environment. This fear is justified where unscientific or illegal forest practices are used, but the argument that there is a need to ‘green the forest sector’ appears to give too little credit to forestry’s core concepts.” —State of the World’s Forests 2012, FAO

THE WOOD IN A BUILDING IS 50 PERCENT CARBON BY DRY WEIGHT18

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Photo: Lawrence Anderson

Architect: DesignARC

To highlight the carbon benefit of wood buildings, U.S. WoodWorks and the Canadian Wood Council partnered with research organization FPInnovations to develop a carbon calculator (available at www. woodworks.org). Based on widely available research, the calculator estimates the amount of carbon stored in a wood building, the greenhouse gas emissions avoided by not using steel or concrete, and how many minutes it takes North American forests to grow that volume of wood.19

The Stella luxury development in Marina del Rey includes both a four-story Type V-A wood-framed building and five-story Type III-A wood-framed building over a shared concrete podium. With approximately 2.3 million board feet (equivalent) of wood, the calculator estimates the following:

  • Carbon stored in the wood: 4,495 metric tons of CO2
  • Avoided greenhouse gas emissions: 9,554 metric tons of CO2
  • Time it takes North American forests to grow this much wood: 16 minutes

Using the EPA’s Greenhouse Gas Equivalencies Calculator, these carbon benefits equate to taking 2,683 cars off the road for a year or the energy to operate a home for 1,194 years.

Although useful as an illustration of wood’s climate change mitigation potential, these results are estimates only, as a detailed LCA would be required to provide this analysis for a specific building.

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Originally published in Architectural Record
Originally published in December 2019

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