How do scientists measure the carbon in trees?
Ever wonder how scientists figure out how much carbon is stored in trees? In the 1950s, scientists realized they could estimate the carbon inside trees, which is now a big part of studying climate change and carbon storage (also called sequestration). As we explain in another post, trees absorb carbon dioxide (CO₂) from the air, trapping the carbon in their trunks, branches, leaves, and roots as they grow.
But how do scientists actually measure it? At first, researchers cut down trees to measure them directly, but that’s not exactly tree-friendly! Eventually, they came up with something better: biomass tables. These tables are based on lots of data from trees that were measured after being cut down. By looking at a tree’s diameter and height, scientists could estimate its carbon content without chopping new ones down.
Let’s break down the steps scientists use today to measure tree biomass (don’t worry, the trees stay standing):
Measuring Diameter at Breast Height (DBH):
Scientists measure the tree’s diameter at about 1.3 meters above the ground (roughly chest height for most forestry scientists, hence the name). They use a special tape to get the circumference, which helps them figure out the diameter. It’s quick, accurate, and doesn’t harm the tree.
Estimating Tree Height:
To measure height, scientists use tools like a clinometer or hypsometer. These help them calculate the angle from their eye to the top of the tree. When they combine that with how far they are from the tree, they can figure out how tall it is—without climbing!
Using Biomass Tables:
Once they’ve got the DBH and height, they check the biomass tables. These tables help translate the tree’s size into an estimate of how much biomass it holds, including the carbon stored inside.
How Good Is This Method?
Even though these methods are old school, they’re still pretty accurate, but just like humans, trees can be a bit unpredictable:
Unusual Shapes: Trees with funny shapes or missing branches don’t always follow the rules.
Different Environments: Trees growing in different climates or soil types might store carbon a little differently.
Over time, newer technologies have developed to make this process even more accurate. Still, the traditional way gives most scientists a close-enough estimate of a tree’s carbon content–which is important for climate scientists and anyone else interested in trapping carbon and keeping the bulk of it out of the atmosphere.
