Trees and Carbon

Kennesaw State University

This activity describes the flow of carbon in the environment and focuses on how much carbon is stored in trees. It goes on to have students analyze data and make calculations about the amount of carbon stored in a set of trees at three sites in a wooded area that were to be cut down to build a college dormitory.

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Notes from our reviewers

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Before students review data collected about other trees, it would be good if they made their own measurements of trees so that the data they review makes sense to them. Putting the data into excel would make some steps in the activity take less time. Students may need guidance through the mathematics. If students are less familiar with logarithmic functions, the formulas can be entered into their excel spreadsheet to handle that step. Rather than having students each measure their lots where they live, groups of students or the whole class can measure a place on or near the school grounds. The activity would be greatly improved if students brainstormed ways that they can save trees or plant new trees as methods to store carbon. Adding a few more questions on the understanding of the carbon cycle would be good to ensure student learning. Measuring tapes might not be readily available but area can be measured by estimates using step length.
Great activity that addresses a common misconception that trees and other plants get most of their mass through the soil. A basic knowledge of reading balanced equations and calculating and molecular mass is necessary to understand some parts of the reading. Comment from expert scientist: The introductory reading materials need some clarification. i) The article uses the term ecosystem when it means biosphere. ii) It calls CO2 a waste product even though it is an end product. iii) Carbon as part of the carbon cycle has 3 phrases: solid, liquid, and gas. The introduction states that carbon exists in only two phases. iv) In plants, sugars are usually dissolved in water and not kept as solids. v) Carbon dissolves in water, it is not absorbed by it as stated. vi) More precise use of term 'equilibrium' is necessary. Human activities have changed the carbon cycle not its equilibrium. vii) Glass window panes are optically opaque in parts of the infrared region of the spectrum. The explanation of the greenhouse effect is misleading, because greenhouse gases do not absorb all of the infrared energy. viii) The increase in average temperatures is 0.6 deg C not 1 deg C. Comment from expert scientist: When teaching this activity be aware that converting forests into housing may sequester more carbon than planting more forests because the decomposition rates of the carbon in housing is usually slower than the decomposition rates of forest.
Great way of quantifying the carbon cycle, very illustrative and easy to modify so that the connection to local environment is drawn. The introduction to the activity is 9 pages of reading which might be a lot for some students in the classroom (It would be a good homework assignment but teachers would need to review it in class as well.)