Forests and Carbon: Carbon Storage in Forest Products with Edie Sonne Hall.
KAXE's Tuesday Morning Show strives to take an in-depth look at some natural resource-based issues important to our region. Producer Mark Jacobs and hosts Heidi Holtan and John Latimer hope to discuss not only the problems but also highlight some creative solutions.
The current focus, Forests and Carbon, is an issue receiving a lot of attention in recent years. In the first segment of the series, Todd Ontl chatted with John and Heidi about how forests sequester and store atmospheric carbon. Stephen Handler described potential changes in Minnesota's forests due to a changing climate in the second segment. In January, Eli Sagor from the U of M.N. discussed their information exchange efforts regarding forests and carbon. In February's episode, Meredith Cornett from The Nature Conservancy described their Natural Climate Solutions initiative. Sawyer Scherer from UPM-Blandin discussed diversity-centered forestry. Last month, we covered biofuels in Minnesota's future with David Pelikan from Conservation Minnesota.
This week, Heidi and John discussed the carbon stored in forest products: Edie Sonne Hall joined them from Three Trees Consulting in Seattle. Award-winner Mark Jacobs is the producer of the Forest and Carbon series and joined the conversation.
This interview has been lightly edited for clarity.
Heidi: Thank you both for being here today.
Mark: Good morning!
Edie: Good morning; it's great to be here!
Heidi: Yeah, good to have you! So, Edie, let's start with you. Tell us about Three Trees Consulting.
Edie: Yeah, absolutely. Three Trees Consulting is an independent consulting firm that specializes in bridging the gap between science and policy and management as it relates to forestry, especially forest and forest product carbon and sustainability. I am the founder and principal. I have a Ph.D. in forest carbon accounting and life cycle assessment, and I've been working on these issues for over 20 years. I grew up in the Northeast. I worked as a wood quality research specialist in the Southeast, in Southwest Georgia, to be exact. And I've been out in Seattle in the Pacific Northwest. I went out for grad school, and I've been here for my career for the past couple of decades. So, I've been to almost all the forested parts of the U.S. except for the North Central and the great state of Minnesota! Although, almost 20 years to this day, I was canoeing in the Boundary Waters on my honeymoon.
John, laughing: You can't do any better than that! Unless... you probably aren't afflicted by mosquitoes in Seattle.
Edie, laughing: Not in Seattle! I believe there were a lot of black flies at the time.
John: Yeah! "Welcome to the Boundary Waters, here's your ration of black flies." Well, tell us about the kind of work you're doing. It's intriguing to me. We look at forests as a way to store carbon, especially older trees. Of course, an older tree is a larger tree, and a larger tree is more desirable for forest products (you can mill a lot of wood out of a tree!). Where does that all go? What happens to the carbon?
Edie: That's a great question. So, back in biology class, we learned that when trees take in carbon dioxide from the atmosphere, they convert that carbon dioxide and water into glucose (C6H12O6). That recombines to form cellulose, which makes up the cell walls. That's where the carbon is stored in your wood or plant material. When you harvest and turn that wood into a product, that carbon stays there throughout its useful life. It only re-emits into the atmosphere upon decay or combustion. So, the length of time of that carbon storage varies tremendously depending on the product. A short-lived product like paper has a half-life of 2-5 years. But if it's a two-by-four that's used to build a home, it's roughly 80 years. Of course, many of you (myself included) live in houses far older than that. So, it really can store carbon for a very long time.
Heidi: It seems like harvesting trees would reduce the amount of forest carbon each year, but that's not true, is it?
Edie: That's a great observation, but you're forgetting one critical part of forests and trees. They are a renewable resource. Because they are renewable, the increase or decrease of the forest carbon on a landscape is dependent on that net impact (how much is leaving the forest and forest product pool due to combustion or decay). So, carbon can either be released from the forest (from harvesting, fire, mortality, or land use change) or enter the forest due to regrowth or an increase in forest size. Believe it or not, the data shows that the more demand there is for forest products, the more incentive there is for planting trees and managing them more productively. It's been shown around the world that the countries with the largest amounts of harvest for industrial uses (wood that goes into making commercial forest products) have the most stable or increasing carbon stocks. The opposite is also true. So, countries with very little harvest for wood products have more loss of forests due to other land use changes. They just don't have that economic value. In the U.S. as a whole, we are growing more than we are losing and have been for quite a long time. It's offsetting on the order of 10-15% of our total U.S. greenhouse gas emissions (quite a lot!).
John: That's pretty encouraging. I work on a spruce project about carbon cycling in bogs. I'm curious about the carbon cycling that takes place with a decaying tree. Let's say you have a tree in your neighborhood (a Douglas fir, for example) that doesn't get harvested. It just topples over. What's the net effect? Obviously, it will decay over time, and carbon will leech out, but how much of that carbon ends up in the belly of a bug, and how much ends up off-gassing?
Edie: That's a great question. The bottom line is that the biogenic carbon cycle is very much a two-way street. This is a natural cycle, and we will always have some leaving the atmosphere. Those trees also break down and provide those nutrients for new seedlings to grow. If you've ever seen a 'nurse log' (that's what we call the old Douglas fir trees that have fallen over), they are a wealth of organic matter and nutrients. Some of that does decay and go back into the atmosphere, but some of it breaks down and provides a solid starting point for new growth. So, it's a cycle, and the key is to ensure the net impact stays out of the atmosphere.
John: So, would it be better then to harvest a tree, take the wood, and build a home or apartment or something, or just let the tree fall and let moss, lichens, and whatnot use that carbon for their own growth?
Edie: That's a great question. It really depends on the risk factor of the location of the forest. Suppose the forested area is subject to natural disturbances, such as fire or insects. In that case, it may make sense to not have as much biomass on the landscape. The other really important perspective in terms of wood products is that we are a society that needs products. We use about a billion tons of natural resources annually, and 74% of those are non-renewable. Those have really big energy impacts. So, if we can use renewable resources (especially wood) that have a lower carbon impact, we will net decrease the amount of emissions in the atmosphere. From a climate perspective, wood products have a triple benefit. They can substitute for materials with higher carbon footprints (such as concrete or steel in the construction sector). They can also store carbon in their wood. And, as we discussed before, they provide an incentive to have more growth in the forest. So, it's a triple impact.
John: I know that there's a lot of work being done right now to augment and make wood products last longer. Are you familiar with that technology, where it's going, and how that might affect carbon?
Edie: Yes, there's a lot of work being done with this circular economy concept. The one-up of that is the circular bio-economy. This is the concept that you're designing both for longevity and for reuse at the end of life: you really make the most of a natural resource. As I mentioned, many innovative products are coming out of the wood product sector designed to make replacements for fossil fuel-based products. This could be anything from cellulose fibers to engineered wood. For example, bioplastics made from pulp byproducts can replace fossil plastics used in our food-grade packaging. Wood foam can be used as insulation in walls and packaging as an alternative to fossil-based polyurethane polyester. There can even be wood-based textiles, which can replace polyester. The big excitement in the climate world has been in the building sector, with the use of mass timber products in buildings typically built with concrete or steel (generally in the non-residential sector). I don't know if you're aware, but there's an innovative series of products that includes things like cross-laminated timber, laminated veneer lumber, and other engineered products that are super strong.
A cross-laminated timber is made of two-by-sixes or two-by-fours glued together, with timber pressed together vertically/horizontally/vertically/horizontally to create a big, super-strong panel. These can be used in buildings that are many, many floors high. In fact, a building in the University of British Columbia that's 18 stories high. As of March 22nd, 11 of these mass timber buildings are being constructed in Minnesota, and five more are being designed. So, this is ticking on! There's a lot more that can be replaced with these buildings. Still, there's a lot of excitement because they have a lot less embodied energy and a smaller carbon footprint. They're modular, so they're easier to build. And they also store carbon. Again, they've got that positive feedback into the forests.
Mark: Edie, one of the buildings I'm familiar with is the T3 building in Minneapolis. That's a seven-story mass timber building. I remember when it was going up, there was a lot of concern about 'wooden skyscrapers' being a fire hazard. Can you talk about that?
Edie: Have you ever lit a match to a big, solid log? Does it light on fire right away? It's a similar concept. There is tons of fire testing being done. They all have to withstand this char test: I don't know the exact details, but fire code is a standard, safe process, and all the materials must meet that code. So, yes, there's lots of work being done on that front.
John: I'm curious about this cross-lamination you were talking about. This isn't like plywood; this is something more. Can you describe the whole manufacturing process a bit more?
Edie: Yeah, a little bit. You'd take lumber, two-by-sixes, for example, and put a series of them vertically. On top of that, you put a series of them horizontally. You repeat the process and use glue and pressure to make enormous panels. (Author's note: here's a video that explains the process: the relevant material starts at 45 seconds.) They can be cut to whatever specifications you need. There are some really unique designs! You can have angles, and some people design curves (incredible!) You can work with the builders, engineers, architects, and manufacturers to have an entire wall or floor system made at the manufacturing facility. Then, it's just a matter of towing it to the site and putting it together. So, it cuts down the building time. There's more upfront work in the design process, but the building process is less.
John: This is incredible, really enlightening. Mark, I'm hoping you'll bring more of this to our listeners because this has been a really edifying piece. I'm anxious to learn more about it, especially this manufacturing process, which sounds really interesting.
Heidi: Edie, is there a good place to send people if they want to read more about it?
Edie: I would say either the woodworks website (they are the designers that help architects and engineers that want to use cross-laminate timber). They have a lot of great information and Think Wood is another website. Those are two good starting points.
Heidi: Absolutely. And you're Edie Sonne Hall from Three Trees Consulting in Seattle. Could you give us your website as well?
Edie: Yes, mine is threetreesforestry.com.
Heidi: Sounds great! Also, Mark Jacobs there is the producer of our programs on Forest and Carbon. You can catch this and all the past conversations on Forest and Carbon on our website. Mark, Edie, thank you so much for being here.
Edie and Mark: Thank you!