FEATURED NEWS 8 West Virginia Forestry Association Mountain State Forestry | Spring 24 www.wvfa.org Forests are an important part of global climate dynamics—the growth of trees influences, and is influenced by, the climate. One result of increasing concern about global climate change is that there is now a market for carbon that includes programs to pay forest landowners to change how they manage their forests. More money for forest landowners and mitigating climate change seems like a ‘win-win’ scenario; however, there is an important forest carbon benefit that currently isn’t getting counted: wood products substitution. This effect is important and, although it is challenging to quantify, we need to fully account for the carbon impacts of wood products—including substitution—if we are to get the full climate benefits of our forests. What is Carbon? Carbon the element is the basic material of life on earth, but the word ‘carbon’ is also shorthand for other concepts in conversations about forests and climate change. For example, the main driver of climate change is ‘carbon,’ a reference to the emissions of carbon dioxide gas (CO2) from the burning of fossil fuels (Figure 1). Carbon dioxide is one of the greenhouse gases in the atmosphere that keeps the earth warm by trapping solar energy. Carbon sequestration occurs when trees grow by capturing carbon dioxide gas (via photosynthesis) and converting it into sugar, which is then converted into other materials such as wood. Biogenic carbon refers to the carbon in living and dead plants. Fossil carbon is the carbon in coal, oil, and natural gas. Biogenic carbon has recently been sequestered from the atmosphere—the oldest trees are only thousands of years old, and biogenic carbon will mostly be released again soon, when the trees rot or burn—likely within the next few centuries or millennia. Fossil carbon was sequestered by plants millions of years ago and, if it weren’t combusted for fuel, would have remained stored in the ‘fossil’ deposits indefinitely. Carbon (dioxide gas) removal from the atmosphere reduces the greenhouse effect. One tree doesn’t do much by itself, but the many trees growing together in the world’s forests result in significant climate impacts. For example, in the United States, our forests remove more than 600 million tonnes of carbon dioxide (TgCO2) each year, an amount equivalent to more than 10% of our nation’s fossil carbon emissions (Figure 2). Forest carbon storage occurs when plant tissue accumulates in the forest—including the wood in living and dead tree stems, roots and leaves, and their breakdown products in and on the soil (litter). Dry wood material (i.e. cellulose, etc.) is about 50% carbon by weight. The carbon stored in wood can be calculated by determining the volume of wood (m3), using the dry wood density to determine wood mass (kg), then multiplying by 50% to get carbon content (kgC), and then multiplying this by 3.67 to get the mass of the carbon dioxide equivalent (kgCO2e). Figure 2. Forest and wood products carbon storage in the United States over time. (brackets) indicate net increase that year in carbon storage in TgCO2. “SWDS” is carbon stored in wood products in landfills. From Domke et al. 2022. Carbon pool 1990 1995 2000 2005 2010 2018 2019 2020 Forest (650.2) (646.0) (622.7) (581.2) (606.7) (583.0) (546.0) (584.4) Aboveground biomass (462.5) (450.9) (435.4) (416.3) (421.4) (406.6) (393.1) (398.7) Belowground biomass (94.2) (91.6) (88.3) (84.2) (84.7) (80.8) (78.1) (79.1) Dead wood (96.8) (98.7) (98.5) (96.8) (100.1) (102.0) (97.0) (101.5) Litter 0.6 (7.0) (1.6) 16.0 0.8 1.3 22.8 (1.9) Soil (mineral) 3.0 2.2 0.9) (0.3) (1.9) 4.1 (0.6) (4.1) Soil (organic) (0.9) (0.8) (0.5) (0.3) (0.1) 0.3 (0.7) 0.2 Drained organic soil 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 Harvested wood (123.8) (112.2) (93.4) (106.0) (69.1) (94.1) (88.8) (83.6) Products in use (54.8) (51.7) (31.9) (42.6) (7.4) (29.0) (24.4) (20.0) SWDS (69.0) (60.5) (61.5) (63.4) (61.7) (65.1) (64.5) (63.6) Total net flux (774.0) (758.2) (716.2) (687.3) (675.7) (677.1) (634.8) (668.1) Forest Carbon Programs Are Missing Out on the Full Goodness of Wood By Adam Taylor, PhD, Professor, University of Tennessee Figure 1. Sources and sinks of carbon globally. From Friedlingstein et al. 2023.
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