I recently gave a presentation on Forest Sector Carbon Strategies and Status in the U.S. entitled, “How you can have your carbon cake in the forest and build with it too.” Architects and builders are increasingly interested in wood as a win-win-win material that is low in embodied carbon, easy to use and reconfigure, and aesthetically pleasing. And yet there is often a “yes, but…?” What about the forest? If we use more wood what happens to the trees? This blog bridges the gap between the product and forest sides of wood use to have your forest and build with it, too.
I am mainly going to focus on carbon but want to start off with some other important aspects of working forests as they are questions/concerns that arise any time you talk about using more wood products. I have compiled a combination of modeling and empirical data—some of it global and some regional/national—to get a sense of how working forests can play an important role in climate mitigation and how this impacts other ecosystem services. Recognize that you could go really deep into each one of these and there are nuances associated with them all; this blog is a very high-level overview. Let’s begin by looking at each of the central concerns.
Concern #1- Does increased demand for wood products cause reduction in supply of forests?
The first concern is about replacement of removed volume over time. How can we harvest more and not be depleting the forest stock? I know it's counter-intuitive, but forest product demand can actually lead to more forests. Peter Ince at the US Forest Service conducted a study a few years ago that looked at industrial roundwood harvest levels and associated deforestation and carbon stock rates by country (note- roundwood is the unit that describes a log that will be manufactured into something without specifying its end use (e.g. sawtimber, plywood, paper). He found that there was no correlation between industrial roundwood harvesting and deforestation—in fact, the opposite was true. “In general, the data show that global regions with the highest levels of industrial timber harvest and forest product output are also regions with the lowest rates of deforestation…The alternative economic hypothesis suggests that forest products and industrial roundwood demands provide revenue and policy incentives to support sustainable forest management, and in turn industrial timber revenues and economical forest management have helped avoid large-scale systematic deforestation in those regions with the highest levels of industrial timber harvest.” The graph below shows industrial roundwood harvest and carbon stock change by region. In this case (as opposed to many other carbon sequestration graphs) a positive carbon value refers to net sequestration (more carbon increasing on the land). You can see that Europe and North and Central America have by far the highest harvest and also have increasing carbon stocks.
Source: Ince, Peter. 2010. Sustainable development in the forest products industry, Chapter 2. Porto, Portugal : Universidade Fernando Pessoa, 2010: p. 29-41. ISBN: 9789896430528. http://www.fpl.fs.fed.us/documnts/pdf2010/fpl_2010_ince001.pdf
Industrial timber revenues can contribute to avoiding land-use change, even in the US. The following graph is created from the 2012 Resources Planning Act (RPA) assessment scenario forecasting for the US South, which predicts forest conditions under different population, GDP, and forest product price scenarios. When all of these are held constant except forest product price, a higher demand for forest products (higher price) will result in 9 million more acres of forest land per scenario than a low forest product price. Multiply that by the average carbon stock per acre in US South, and that is the equivalent of 660 million tons CO2 sequestered by 2060. This means that higher demand for timber contributes to forest, and carbon, protection.
Source: Wear, D., R. Huggett, R. Li, B. Perryman, and S. Liu. 2013. Forecasts of Forest Conditions in U.S. Regions Under Future Scenarios: a technical document supporting the Forest Service 2012 RPA Assessment. Gen. Tech. Rep. SRS-170. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station.
And indeed, we can see from empirical data that demand can influence supply. Economic trends show that higher demand leads to more supply (growth). The graph below is US Forest Growth Removals Mortality and Inventory. You can see that inventory has gone up even as removals (harvest) have increased. Before the Great Recession, harvest levels increased 35% from 1952 and inventory increased 50%. The future trend is unclear, though, as harvest seems to be trending downward and mortality has increased since the late 1980’s.
Source: USFS 2014 US Forest Resources Facts and Historical Trends.
Together, these examples show empirical evidence that supply can increase to meet or exceed increasing demand. The question is why? With a higher demand for forest products, landowner have revenue and incentives to invest in forest planting and management, which for forest products keeps forests as forests and increases forest productivity.
Concern #2: How can we be assured of forest sustainability?
A second major concern relates to forest sustainability. If we are harvesting trees, what are we doing to water, wildlife, and all those beautiful forests? How can be we assured of forest sustainability in the US?
Forest Certification
Forest certification is a mechanism for forest monitoring and labeling timber, wood and pulp products and non-timber forest products, where the quality of forest management is judged against a series of agreed standards (WWF, 2018) . The highest level of sustainability assurance is third-party forest certification. Forest certification assesses a landowner’s forest management against a series of agreed standards related to water quality, biodiversity, wildlife, and forests with exceptional conservation value. There are about 96 million acres certified forests in the US, which is about 19% of total US timberland—above the global average of 11%.
The three major systems, Sustainable Forestry Initiative (SFI), Forest Stewardship Council (FSC), and American Tree Farm System (ATFS)—shown in the graph below—all have slightly different principles and procedures. SFI is a single-standard North American program. FSC is a global program with regional standards. ATFS is geared toward smaller US landowners. While you can debate the nuances, there is more assurance of sustainable forest management with any of them.
Source: State of America’s Forests. 2019. https://usaforests.org/
Responsible Fiber Sourcing
You will never be able to get all forests certified, especially with the majority of private land owned by small family landowners. The next level of assurance can be achieved from responsible fiber sourcing. The three major responsible fiber sourcing standards are summarized below, taken from a great module on “the role of forest certification” from Green Blue.
"1. PEFC Controlled Sources: In May 2013 PEFC published a revised PEFC Chain of Custody standard, which allows organizations to handle fiber from non-PEFC certified forests and to sell it with a ‘PEFC Controlled Sources’ claim. This claim demonstrates that a risk assessment was implemented to ensure that the fiber from these uncertified forests is legal and in compliance with relevant regulations. In addition, it avoids controversial sources and does not allow fiber to be sourced from genetically modified trees or from land converted to non-forest use.
2. FSC Controlled Wood: A company level certification developed and published by the Forest Stewardship Council (FSC). This standard specifies material from acceptable uncertified sources that can be mixed with FSC-certified material in products that carry the “FSC Mix” label. This standard aims to ensure the avoidance of ‘bad wood’, which includes wood that is illegally harvested, harvested in violation of human rights, harvested in threatened forests with high conservation values, harvested in forests being converted to plantations or non-forest use, or wood from forests with genetically modified trees.
3. SFI Fiber Sourcing: A standard to certify manufacturers of wood products, which source fiber from a variety of sources, requiring them to show that the raw material in their supply chain comes from legal and responsible sources. The standard aims to avoid controversial sources by avoiding illegal logging and fiber sourced from areas without effective social laws. The fiber sourcing requirements also go further by including measures to broaden the practice of biodiversity, use forestry best management practices to protect water quality, provide training to foresters, engage in research, and outreach to landowners. This standard encourages the spread of responsible forestry practices such as conserving water quality, providing outreach to landowners and using the services of trained forest management and harvesting professionals."
Resources for further information about responsible fiber sourcing: https://www.treehugger.com/corporate-responsibility/new-webinars-engage-marketplace-responsible-forest-sourcing.html
Water Quality from Best Management Practices
One of the ways we can assess forest management impact on water is by tracking compliance of Best Management Practices (BMPs). These are regionally appropriate guidelines for streamside buffers and road construction to reduce erosion and maintain water quality. BMPs, whether regulatory, quasi-regulatory, or non-regulatory (voluntary) are tracked in the US and are above 90% compliance in all states (see below). This is important as forests are important protectors of water supply. About 60% of water is sourced from forests across the nation and up to 75% in the West.
We can be assured that timber is harvested sustainably in ways that support water quality, biodiversity, and habitat through mechanisms like forest certification, responsible fiber sourcing standards, and best management practices.
Concern #3: Does wood product demand cause deforestation?
The third concern people express is that wood product demand leads to deforestation. This is, almost by definition, not true. Deforestation (land-use change) occurs when there is a higher demand for the land than wood products. As you can see from the WWF figure below, in no region at risk of deforestation is logging or wood product demand the primary cause of forest loss and/or severe degradation.
Source: WWF. 2015. WWF Living Forests Report: Chapter 5 Saving Forests at Risk. http://assets.worldwildlife.org/publications/793/files/original/Report.pdf?1430147305&_ga=1.26569597.1522058232.1430426384. Accessed 3/17/16
In fact, in the US and Canada, where there is a healthy forest products market, there is “extremely low risk of deforestation” as confirmed by the WWF report. [Note, while the U.S. is the largest producer of industrial roundwood, not all of the wood products consumed in the U.S. are harvested domestically. Consumers should still be aware of where their wood product comes from].
Source: WWF. 2015. WWF Living Forests Report: Chapter 5 Saving Forests at Risk. http://assets.worldwildlife.org/publications/793/files/original/Report.pdf?1430147305&_ga=1.26569597.1522058232.1430426384. Accessed 3/17/16
Demand for wood products does not contribute to deforestation, and in fact, provides incentives to keep land as forests instead of converting it to other uses like agriculture or development.
Concern #4: Is using wood the best carbon mitigation pathway? Isn’t it better to let trees grow?
Ok, fine. You may be convinced that using wood products sourced in the US helps keep forests as forests, which in turn provides a bunch of co-benefits. BUT…for climate change, wouldn’t it be better to just let the trees grow?
First, I’m going to tell you where we are now. In the US, our forests are a huge carbon sink—on the order of 10-15% of our nation’s greenhouse gas (GHG) emissions, depending on the year.
Source: US EPA GHG Inventory, Chapter 6. From https://www.epa.gov/sites/production/files/2019-04/documents/us-ghg-inventory-2019-chapter-6-land-use-land-use-change-and-forestry.pdf
The table below shows the net change in carbon stocks and harvested wood products (HWP) each year since 1990 and is the table form of the graph above. You can see wood products provide a small, but important contribution. You’ll also notice that net sequestration is trending down slightly, meaning that the forests are still accumulating carbon but at a slower rate.
Source: US EPA GHG Inventory, Chapter 6.
The graph below is growing stock and timberland area by region. You’ll notice that the US South has doubled its growing stock since 1953.
Source: State of America’s Forests. 2019. https://usaforests.org/
Now I’m going to tell you a bit of why we are currently in a huge carbon sink. It’s because we heavily cut the forests 150 years ago and converted land in US South and Northeast to farmland. Since the turn of the last century, land has been converting back to forests. For the past 100 years, the total forest area in the U.S. has been stable and even grew by two million acres from 2000 to 2005, a time when timber markets were strong. The first graph below shows that forests were net carbon sources (black line above the X axis) when they were cut over past centuries, but returned to net carbon sinks (black line below the X axis) as farmlands converted back to forests. The second graph, however, projects future sequestration under different emissions scenarios. It shows that forests will become net carbon sources (colored lines above the X axis) in the latter half of this century due to loss of forest area and accelerating disturbance rates. The U.S. Forest Service projects a loss of 16-34 million acres of forestland in the U.S. by 2060. The South is expected to have the greatest loss of forest at 9-21 million acres.
Source: USFS, 2012: Future of America’s forest and rangelands: 2010 Resources Planning Act assessment. General Technical Report WO-87. 198 pp., U.S. Department of Agriculture, U.S. Forest Service, Washington, D.C.
So, what does that mean for climate mitigation? We’ve been talking about how our US forests are a great carbon sink and now you’re saying it’s going to go away? Let’s put things into perspective. Below is a hypothetical graph—the US hasn’t made any commitments to get to 0 net emissions by 2050- but some reports believe that is what is needed to stay below 1.5 degrees C of warming. If that’s the case, we not only have to cut current annual emissions but also make up for the 645 MMT CO2 sink we are currently enjoying from the land sector. The reduction of sink strength is inevitable at some point if just focused on carrying capacity of land; however there are MANY opportunities to slow down the rate of reduction and many ways land can be used to help reduce both fossil and biogenic C emissions.
Source: 1990-2015 from US EPA. 2019. https://www.epa.gov/ghgemissions/inventory-us-greenhouse-gas-emissions-and-sinks-1990-2017. Projections modeled based on IPCC science target. Sequestration projections from RPA assessment
What can the forest sector do? Below a graph I adapted from the 2016 UN Food and Agriculture Organization report, “Forestry for a Low Carbon Future.” The report lists six key mitigation strategies: 1) plant more trees, 2) increase carbon density/stocks in existing forests, 3) increase wood product carbon storage, 4) reduce deforestation and degradation, 5) use biomass for energy, replacing fossil fuel, and 6) use wood products in construction materials, avoiding fossil fuel emissions in manufacturing products with higher combined emissions. Four of the strategies deal with the land-atmosphere interaction and two of them help reduce fossil fuel use. Remember, the goal is to minimize CO2 in the atmosphere, which can be accomplished by pumping more CO2 into the land, or allowing less CO2 from fossil fuel (or land) to enter the atmosphere. All of the elements in the figure interact with each other. For example, producing more wood products may reduce forest carbon but lead to a greater reduction in fossil fuel emissions overall. The greater question is, how do you look at them all together?
The next graph presents one set of options: focusing on the land side through natural climate solutions. The graph, taken from a recent TNC analysis, shows there is a lot of potential here in the US. Reforestation puts more land in forests. Avoided conversion and fire management prevent emissions. Of the top three options, those are the most straightforward. The natural forest management mitigation option is large, but in this case assumes a 10% reduction in harvesting from current levels (Fargione et al 2018). When you reduce harvesting you are reducing the supply of wood products, which may lead to more harvesting in another country or consumers to choose other materials with a higher carbon footprint instead, generally known as substitution.
Source: Fargione et al. 2018. Natural Climate Solutions for the United States. Science Advances 4 (11)
Wood products not only take less energy to manufacture than other more energy-intensive materials; they store carbon long-term over their useful lifetime (which varies depending on the end-product). The graphic below shows how the carbon storage for a given acre of working forestland is calculated over time. This shows the forest itself in green at the bottom, long- and short-lived products above that, and then includes credit (in orange and blue) for substituting wood for more emissions-intensive materials. When you include the substitution benefits of already managed forests, the benefits are often higher with continued harvest than leaving it to grow.
That is not to say you should do this in all forests. If there is one take-away I can communicate, it is that across a landscape, forests should be serving different purposes. Some should be managed intensively for wood products and some should be managed as forests with exceptional conservation value.
Climate-Smart Forestry (CSF) is a targeted approach or strategy to increase the climate benefits from forests and the forest sector, in a way that creates synergies with other needs related to forests. The approach builds on three pillars: 1) reducing and/or removing greenhouse gas emissions to mitigate climate change; 2) adapting forest management to build resilient forests; and 3) active forest management aimed to sustainably increase productivity and provide the full suite of forest benefits. There is the potential to sequester ADDITIONAL carbon on the landscape by focusing on healthy, resilient, and productive forests. In a future blog I will discuss just what these can be.
In sum, wood products as building materials are one important climate solution because they take less energy/emissions to manufacture than other materials and store carbon through the useful lifetime of the product. Wood products are one critical forest use that is complementary with other forest uses for climate and conservation benefits.
Hopefully by now I have started to answer some of your concerns about using wood products. They are summarized below.
1) Increase in demand for wood can support investment into forests and ultimately increase supply.
2) Forests can be managed to protect water quality, wildlife, soil, and areas of high conservation value. Assurances can be made through forest certification, responsible fiber sourcing certification, and state regulatory or voluntary best management practices.
3) Demand for wood does not cause deforestation. In fact, demand for wood ensures value to forests.
4) Using wood products can be part of a climate solution but should not be the only pathway. Climate Smart Forestry can provide the following benefits:
• Use wood products to drive carbon sequestration in forests
• Will get/keep more forests (afforestation and avoided conversion)
• Will get benefits from substitution
• Focus on resilient, healthy, productive forests
• Will keep more forests from disturbances (fire, insect, disease)
• Will get more carbon in existing forests
• Use a landscape approach
• Some forests (with low risk of disturbance and other ecosystem attributes) should be carbon reserves
• Some should be managed to reduce risk of disturbances
• Some should be managed for wood product production