Learn How to Measure a Tree with Ms. Jackson’s Forest Ecology Class!

Here at Dublin School, we are fortunate to have a breathtaking campus and unrestricted access to the outdoors. Science Department Chair Katri Jackson has taken full advantage of both of those facts with her Forest Ecology class, where students immerse themselves in our School’s ecosystem to better understand the natural world around them.

In creating the class, Ms. Jackson’s goal was “to get the students to be curious about the ecosystem that surrounds them, using this forest. Ultimately, she shared, she wants to inspire them to be curious about any ecosystem they may one day find themselves in.

On Monday, September 21, the class learned how to measure a tree — both its age and its height. This involved the use of tools like a clinometer, which measured the angle students’ eyes had to reach to see the very top of their assigned tree; a tape measure, to measure distance from their trees and the circumference of their trees; and graphic calculators, to help with the required trigonometry.

Figuring out a tree’s age is simple enough, as students learned. You start by measuring the tree’s DBH — Diameter at Breast Height. “Breast Height” is a standard height in forestry: 4.5 feet. To do this, students used a “d-tape” — a special measuring tape that converts circumference to diameter. This must then be multiplied by the tree’s growth factor, which is different for each kind of tree. Sugar Maples, for example, have a growth factor of 5. These calculations will tell you how old any given tree is in years. Students got to test these calculations out for themselves with a variety of different trees on our Quad.

Next came the harder part — calculating a tree’s height! This is where the trigonometry comes in. Most of our trees on campus are too tall to just be measured with a tape measure. Students had to get fancy, using their own distance from a tree and the elevation angle required to see the top of the tree. Once both of those numbers were found, students could use the tangent of the elevation angle to figure out the tree’s height — but they had to remember one final step! Once their trigonometric calculations were complete, students had to remember to add one final number to get their tree’s final height — the distance from their eyeballs to the ground. Because the elevation angle they used was from eye-level, that distance was not factored into their calculations.

Ms. Jackson ended class by showing students one more way to discover a tree’s age — coring the tree and counting its rings. She had an increment borer (the tool used to core trees) on hand, and Dunkin Donuts straws to store the pieces of tree safely. Students got to use the borer themselves, which required patience and coordination. It was a very hands-on day in Forest Ecology, keeping the students busy!

Still to come in the semester, students will be learning about:

• Plants, including scrubs, moss, grass, sedges, and more. This will help them understand the diversity of plants that we have on campus, and the threats to this diversity — invasive pests, malicious plants, and human uses of the land.
• Animal interactions in the forest. Students will place game cameras on our trails, meet with a biologist from the Harris Center to sample their salamander plots, and meet with a Harris Center Ecologist to talk about mammals in the forest and how to track them.
• Conservation and research. Students will visit the Fox Forest in Hillsborough, New Hampshire, to learn about their Chestnut Regeneration project. They will also go to the Hubbard Brook Research Forest for a tour of their research while learning about how long-term forest research shapes management policy.
• How to appreciate the value of nature and the health of the planet, among other valuable learning skills!

Thanks, Ms. Jackson, for letting me tag along for the day! Forest Ecology is an incredible example of how we strive to push our students to think outside of the box; notice, question, and appreciate the world around them; and challenge themselves to try new things.