Silviculture to maintain and enhance forest carbon sinks

Weyerhaeuser Company, one of the world's largest private owners of timberlands, owns or controls approximately 11 million acres of timberlands in the US and manages additional timberlands under long-term licenses in Canada. These timberlands are managed on a sustainable basis in compliance with internationally recognized third-party forest certification schemes. Weyerhaeuser is also one of the largest manufacturers of wood products in North America.

The company’s role in addressing climate change began with drastically reducing its GHG emissions and producing low-carbon energy sources and materials. But its most significant contribution is through the provision of carbon sinks, as its forests grow and naturally sequester carbon dioxide from the atmosphere. After harvest, new trees are replanted to perpetuate the cycle. Every year, its growing landscape of trees absorbs more carbon than they remove through harvest (1). Weyerhaeuser recognizes its responsibility to manage its forests to maximizes their contribution to climate change mitigation and improve their resilience to the impacts of climate change. For that, several silviculture practices are implemented to ensure forests stay healthy and productive and continue to act as a natural climate solution for decades to come.

Silviculture (2) describes all the decisions and management practices that enable forests to meet the diverse needs of society, such as wildlife habitat, timber, water, recreation, and carbon sequestration. Because the specific action taken will depend on the stage of forest management, the geographic location, or the climate risk being mitigated, the practices were grouped into four categories: Climate-resilient traits (Group 1); decision and prioritization tools (Group 2); engineering controls (Group 3); disaster response plans (Group 4):

Silviculture Practices Group 1: Climate-resilient traits

• While Weyerheauser historically has maintained a large breeding population of seeds in its nurseries to capture genetic variation, it is increasing the rate of selection for adaptive traits, like drought tolerance, disease, and insect resistance.

• The company’s forest scientists are conducting long-term research on tree viability under different climate scenarios. This includes migrating and testing family selections further north or at higher elevations.

Silviculture Practice Group 2: Decision and prioritization tools

• Building on Weyerhaeuser’s skillset of precisely deploying seedlings based on site conditions, competing vegetation, and other environment factors, it is updating its minimum winter temperature maps and identifying drought-prone areas to deploy families best adapted for predicted future conditions.

• To take advantage of technological advancements to aid in climate-resiliency, the company is expanding the use of remote sensing tools for infrastructure and planning.

• Because of the interrelated nature of forest management and water quality, the company is evaluating interactive effects of forest management and climate change on long-term water quantity and quality, including gathering data on stream temperatures, to inform riparian buffer configurations.

• And because animal and plants species in forests are attempting to adapt to climate change as well, Weyerhaeuser is incorporating the risk of climate impacts and the adaptive capacity of species into its biological risk assessments.

Silviculture Practices Group 3: Engineering controls

• Climate change is bringing the risk of more frequent and more severe storms to many of Weyerhaeuser’s forests. While not all damages are avoidable, the company is deploying next-generation sensor networks for early detection of extreme events such as floods, droughts, extreme heat, and wildfire at seed orchards and nurseries to mitigate the risks to the most venerable age of trees. It is also replacing road infrastructure, such as culverts and cross drains, with larger units to handle larger flow events.

• The company is also regulating water levels during and following storms for low-topography coastal areas with ditch maintenance, tide gates, and weirs.

Silviculture Practices Group 4: Disaster response plans

• Climate change is increasing the risk of negative forest health impacts due to pests and disease, so Weyerhaeuser is deploying widespread pathogen and insect monitoring system, including remote sensing tools.

• And to prepare for the worst impact of climate change, the company is developing road maintenance and abandonment plans that incorporate the increased risk of extreme stormflows.

Climate impact

Targeted emissions sources

The biggest GHG impact of these solutions is maintaining the carbon balance of forests in the face of climate disruptions. Although the guidance for accounting for forest carbon is still under development (3)(4)(5). Weyerhaeuser currently reports the net change in carbon stocks (the combined impact of growth, harvest, and mortality) in its forests as a Scope 1 GHG impact (6). If there is more carbon stored in its forests year-over-year, it is reported as a removal. If there is less carbon, this would be reported as an emission. Integrating climate risks into silviculture practices allows the company to continue to maintain or increase the important amount of carbon stored in its forests.

Weyerhaeuser’s customers are also responsible for a Scope 3 (category 1) GHG impact based on products they make using the company’s harvested logs. When Weyerhaeuser manages its forests to be a net sink of carbon, it passes along a Scope 3 removal benefit to its customers, based on each customer’s allocation of the overall net change on the company’s land.

Companies should refer to the latest guidance from the GHG Protocol, International Standards Organization and other relevant national or regional entities to determine which emissions and removals sources this action targets (6)(7)(8).

Decarbonization impact

When silvicultural practices are successfully employed, the net Scope 1 impact of it’s the company’s land remains at or below zero, meaning that its forests continue to act as a carbon sink. Over the previous three years, Weyerhaeuser’s forests removed an average of 8.7 million metric tons of CO2e (9) from the atmosphere. That’s the equivalent of the emissions from 22 natural gas-fired power plants each year (10).

Business impact

Benefits

• Employing these silvicultural practices is an integral part of Weyerhaeuser’s business plan and maintains a sustainable supply of fiber that is used to build homes and make essential products needed by society.

• Because climate change is expected to worsen over the coming decades – even if the world can limit warming to 1.5C – actions taken today will improve the resilience of forests to more severe climate impacts.

Costs

The costs associated with silvicultural actions are built into operational costs and forestry research spending. In 2022, Weyerhaeuser’s total costs for its timberlands business unit were $1.8 billion (11). This include costs related to seedlings, planting, silviculture, harvest, and hauling , but costs are not broken down by individual activity. In addition, the company spent $11.5 million on forest research in 2022, most of which was directed toward forest health and productivity research (12). Weyerhaeuser uses the outcomes of research spending to develop silviculture plans that incorporate the latest climate-science and operationalizes this research using the total allocated costs for its Timberlands business.

In 2022, the US government passed the Inflation Reduction Act (13), which contained over $380 billion for energy and climate initiatives through 2031. Although the funding is in the early stages of being deployed, Weyerhaeuser expects to be able to take advantage of several forest provisions to help enhance its ability to implement climate-smart forestry practices:

• Conservation Programs: $20 billion to Climate-Smart Agriculture via NRCS programs that in many cases include tree and forest-related practices

• Climate-smart Forestry: $450 million to the US Forest Service for forest carbon incentives to private landowners

• Science, Data and Innovation: $100 million for US Forest Service Wood Innovation and $50 Million for inventory of old growth and mature forests on national forest system lands

Impact beyond climate and business

Co-benefits

In addition to the carbon benefit, Weyerhaeuser’s working forests provide numerous other benefits to neighboring communities and broader society. All the living things in a forest — plants, animals, insects and fungi — interact with each other and with the soil, water, and air to form a healthy and biologically diverse forest ecosystem. Forests also provide important benefits, such as clean drinking water, clean air and carbon sequestration, as well as other cultural benefits, such as hunting and foraging. Managing forests for climate-resilience helps maintain these important co-benefits.

To increase recognition of the full value working forests offer, Weyerhaeuser reports publicly on a select set of the additional ecosystem services provided by its timberlands (14), including the following:

• Mushroom and berry harvesting

• Honey production

• Fur production

• Renewable energy agreements

• Managed and protected habitat

• Conservation programs

• Recreational access

• Special and cultural sites

• Education

Potential side-effects:

Working forests must balance the need for a sustainable supply of timber against the impact and dependence on nature. To preserve and protect the ecosystem balance, companies can take the following actions:

• Regularly conducting biodiversity assessments across forests. These assessments, which include analyzing species occurrence data and monitoring for the presence of threatened or endangered species, guide and inform the implementation of habitat conservation and species management plans.

• Leaving buffers along riparian areas, surveying sites for species occurrences prior to harvest activities, refraining from harvest during certain times, and managing for specific habitats using prescribed burns or thinning harvests.

• Participating in the development of the forest sector guidance for the Taskforce on Nature-Related Financial Disclosures (TNFD) (15) and using the results of that guidance to inform nature strategies moving forward.

Working forests and silviculture practices must also maintain a respect for local and Indigenous communities, whose needs and knowledge are relevant to many decisions that are made on the land. Building and maintaining relationships specific to each operating area is key to achieving successful outcomes. For example, Weyerhaeuser provides financial and in-kind support for two local Indigenous communities in Grande Prairie, Alberta – Horse Lake First Nation and the Aseniwuche Winewak Nation – to identify, validate ,and catalogue important cultural and tradition knowledge.

Typical business profile

This action is applicable to forest managers of all sizes in all geographies. While the implementation should be tailored to each specific context, silviculture encompasses a suite of actions and provides a framework by which to apply climate-smart practices on land that will enhance forest carbon stocks, protect against climate-related disruptions, and enable forests to continue working as a natural climate solution for decades to come.

Purchasers of forest carbon products are encouraged to engage with their suppliers to increase the uptake of this suite of actions in their supply chains.

Approach

Group 1: Climate-resilient traits

Over decades, Weyerhaeuser has conducted research on the impact of seed selection on seedling viability and tree survival rates. In the face of climate impacts, seeds must be selected that are known to have the highest chance of surviving these more extreme conditions.

Group 2: Decision and prioritization tools

The implementation of this set of tools (updating maps with climate information, expanding remote sensing tools, and improving models of water quantity/quality and wildlife species) should be tailored to each forest manager’s technological capabilities.

• For landowners with access to large amounts of data and technical tools, the focus should be on integrating climate information into existing data sets.

• For smaller landowners or for forest managers who do not have access to readily available data, a more appropriate starting point would be to identify third-party solutions providers who could provide these at lower cost.

Group 3: Engineering controls

Some coastal forests are at risk of transitioning away from productive pine stands due to the impacts of saltwater, such as storm inundation, sea level rise, erosion, and sea spray, confounded with land subsidence. By deploying engineering controls, foresters can take protective measures to maintain tree viability and modify practices on affected stands to mitigate the worst of the impacts.

Group 4: Disaster response plans

Weyerhaeuser is investing in remote sensing forest health monitoring tools to improve its understanding of how plant species are responding to the impacts of climate change. Testing promising technologies and determining the appropriate scale provides opportunities to treat forest stands in advance of decline or prevent large-scale losses associated with pest outbreaks and disease occurrence. By course-correcting a handful of problematic stands annually, the costs of these investments can typically be justified.

Stakeholders involved

Group 1: Climate-resilient traits

Regeneration facilities, including seed orchards and nurseries, have staff and machinery on-site responsible for seed selection and for ensuring a large variety of seeds are established into viable seedlings. Forest managers are then responsible for ensuring seedlings are properly planted to maximize the survival rate of young trees.

Group 2: Decision and prioritization tools

The implementation of these tools begins with partnerships between data science and geospatial teams, and on-the-ground calibration. Once data has been collected, foresters must be given guidance on how to operationalize the tools.

Group 3: Engineering controls

Deploying engineering controls requires partnerships between foresters, researchers, and local regulatory bodies due to the sensitive nature of coastal ecosystems.

Group 4: Disaster response plans

These projects are typically led by forest scientists with the help of operational staff in the forest to collect data and implement necessary treatments to avoid the worst climate impacts before they occur. Certain technology providers, such as remote sensing companies, can be helpful partners in these projects.

Key parameters to consider