Recently we visited our tree farm in Miller County Arkansas. We have a new forestry consultant since the individual we had worked with for many years retired. This was our first meeting with “Jay” and he suggested we meet at the site (he referred to it as a “plantation” which made us walk a bit taller).
I first wrote about our tree farm last March in a blog entitled “Éarth Day 2019”. In that post, I described the environmental benefits of trees – particularly their ability to absorb carbon dioxide – from the atmosphere. My sister and I came to be “tree plantation owners” by inheriting this land from our grandmother many years ago and instead of selling the land, we decided to plant a forest of loblolly pines. Our trees were planted according to the methods prescribed by the U.S. Forest Service (an agency of the U.S. Department of Agriculture) in 1992. Fourteen years later, we had the tract thinned for the first time, and 10 years later, thinned again. Thinning the trees allows the remaining trees to grow faster since the remaining trees have more resources (water, soil) and room to grow. Our discussion with Jay focused on our next steps – namely, should we thin again now or wait a few years to thin again, or should we clear-cut the tract and start the process again with new seedlings.
When we initially decided to create this “forest”, my motivation was primarily as an investment. I recognized the payoff for this investment would take a long time since the financial proceeds from the early thinning would be modest. Smaller trees that are thinned are used primarily to make pulp since they are too small for lumber. But as the trees mature, they are suitable for lumber and price we will receive “per ton” is much higher than the price for pulp. Wait long enough and one of these trees just make a fine telephone pole. It’s been 28 years since we planted these trees. Typically, forest managers suggest a 30-35-year cycle from planting to a final harvest.
As I contemplated what we should do now, I had mixed feelings about how to proceed – especially considering the importance of trees to our planet. Cutting them down stops them from absorbing more carbon dioxide. But planting new ones starts the process again. I thought, maybe we should just leave them alone for a while, or forever. And I must confess, I was a little confused about what happens to the carbon that has been absorbed over the years by these trees.
After a bit of research, I found an article written by R. Philip Bouchard entitled “Trees and Carbon Dioxide: What Is The True Connection?” It begins with the basic premise that “trees absorb carbon dioxide” but goes on to explains what happens next. The article also described some of the common myths and misunderstandings on this subject. At the risk of oversimplifying a detailed and well written article, I learned that trees absorb CO2 and then use the energy of sunlight through the process of photosynthesis to store the sun’s energy by combining CO2 and water molecules to form carbohydrates. The stored energy, in the form of sugar, is then used for the plant to live. The sugar that is not used for energy is converted to other carbon compounds including cellulose – the “woody” part of the tree. In other words, the “wood” in the tree contains carbon compounds created from the CO2 and acts to hold these compounds locked in storage. These carbon compounds will remain intact unless the wood is allowed to decompose or burned, which in both cases, will result in CO2 being released back into the atmosphere.
So instead of just leaving our trees alone, I concluded the best and most responsible thing to do was to properly manage our trees to grow more wood. Thin them when it benefits the further growth of the remaining trees, and clear cut when the trees are mature. Clear cutting is important because after a forest becomes mature, the natural decaying process releasing CO2 begins to offset the CO2 the tree can absorb. Most literature (but not all) suggests that at some point, the net amount of carbon absorbed by a mature forest can reach a steady state and the forest can cease to sequester more CO2. Said another way, a mature forest stops sequestering more CO2. Other studies conclude that younger forests are much better than mature forests in sequestering CO2, again suggesting that the rate of sequestering carbon dioxide capture starts to taper off as the trees mature.
While there may be differing views on how much CO2 an older or mature forest can sequester, it seems reasonable that the amount of wood that is grown tracks with the amount of CO2 sequestered. In other words, the more “wood” you grow, the better for sequestering CO2 and better for the planet. Responsible timber management, which has an objective to grow wood, follows a “plant, thin, and harvest cycle”. By using this cycle, we avoid the “wood” decaying or burning and releasing CO2 and instead, put the wood to a productive use.
And what productive use? For construction, wood is the only major sustainable and renewable resource building material. The American Forest Foundation, points out that “Wood is better for the environment in terms of greenhouse gas emissions, air and water pollution, and other impacts. In contrast, steel and concrete consume 12% and 20% more energy, emit 15% and 29% more greenhouse gases, and release 10% and 12% more pollutants into the air, and generate 300% and 225% more water pollutants than wood, respectively.”
And construction using wood is not limited to small scale projects like homes. Architects and builders are now using wood for significantly larger projects using a product referred to as “mass or massive-timber”. “Mass-timber” is a generic term that encompasses products of various sizes and functions, like glue-laminated (glulam) beams, laminated veneer lumber (LVL), nail-laminated timber (NLT), and dowel-laminated timber (DLT). But the most common and most familiar form of mass timber, the one that has opened up the newest architectural possibilities, is cross-laminated timber (CLT). To create CLT, lumber boards that have been trimmed and kiln-dried are glued atop one another in layers, crosswise, with the grain of each layer facing against the grain of the layer adjacent. Stacking boards together this way can create large slabs, up to a foot thick and as large as 18-feet-long by 98-feet-wide, though the average is something more like 10 by 40. (At this point, the size of slabs is restricted less by manufacturing limitations than by transportation limitations.) Slabs of wood this large can match or exceed the performance of concrete and steel. The world’s tallest mass timber structure, at 18 stories and over 280 feet, was recently built in Norway and there’s an 80-story wooden tower proposed for Chicago. CLT is gaining momentum in the United States exemplified in September, when Governor Jay Inslee (known for his environmental leadership) celebrated a new mass timber manufacturing facility in Spokane, Washington.
Some groups have expressed concerns that “mass-timber” could trigger massive deforestation with significant negative impacts to the environment. This is true if the trees for mass-timber were not grown and harvested in a responsibly managed way. But if coupled with climate-smart forestry practices, it is clear (at least to me) that mass-timber offers many significant advantages when compared with concrete and steel.
Bottom line, I’m very happy that what we decided to do 28 years ago as an timber investment has benefited, and will continue to benefit the environment. We plan to have our trees thinned now and expect, in about 7 years, we will have the tract clear-cut and replanted. Something to hand off to our next generation. And I’m convinced that overseeing a well-managed forest is one of the best decisions I can make – both in absorbing and storing CO2 and providing some next generation “green” products to displace concrete and steel.
And finally, a note of thanks and appreciation to my cousin Gary for his insights in helping me understand the science of CO2 and trees.