Carbon Sequestration in Campus Trees

Robert S. Cole, The Evergreen State College, Olympia, WA 98505 rscole@evergreen.edu
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This material is replicated on a number of sites as part of the SERC Pedagogic Service Project

Summary

In this Spreadsheets Across the Curriculum module, students will build a spreadsheet to calculate the net carbon sequestration in a set of trees using an allometric approach based upon parameters measured on the individual trees. Students determine the species of trees in the set, measure diameter at breast height (dbh), and, from the allometric relationships determined by forestry researchers, use the spreadsheet to calculate carbon content of the tree. Students can then compare their data to that measured a year earlier on the same set of trees, to determine the rate of carbon sequestration.

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Learning Goals


In this module, students will
  • Use Excel to model the amount of carbon stored in a tree.
  • Compare amounts of carbon stored by tree species,and by diameter of tree.
  • Compare the diameters of trees from one year to the diameters of the same trees a year earlier, in order to compute the rate of carbon storage.
In the process, students will
  • Develop Excel skills including entering equations, filling cells, and interpreting the results of computations.
  • Develop a sense of how allometric relationships are used to help calculate biomass in the biological sciences.
  • Develop an understanding of how the power function is related to linear plots on log-log graphs.
  • Be able to begin to compare the magnitude of carbon storage in trees to carbon dioxide produced by human activities.

Context for Use

This module is used in an Introduction to Environmental Studies program at The Evergreen State College. It could be used in any course that deals with climate change, global warming issues, or carbon budget or carbon cycle calculations. It would be particularly useful when combined with students measuring actual tree diameters on campus as a field work component. Such activites could form the basis of a long-term database of campus carbon sequestration. This module could be adapted to upper division classes quite readily.

Description and Teaching Materials

SSAC2006.QC879.8.RC1.1 (PowerPoint 245kB Jan10 08)
This module is a PowerPoint presentation with embedded spreadsheets. Students work though the presentation, answering questions and developing the spreadsheet. If the embedded spreadsheets are not visible, save the PowerPoint file to a disk and open it from there.

This PowerPoint file is the student version of the module. An instructor version is available by request. The instructor version includes the completed spreadsheet. Send your request to Len Vacher (vacher@usf.edu) by filling out and submitting the Instructor Module Request Form.

Teaching Notes and Tips

This module is best used when data on a given set of trees are available from prior years. In the absence of prior year's data, the module can be used to start the data collection process for the following year. Assuming that data from field measurements are available to students, this module could be used as a homework exercise, or as a lab exercise. The module is also useful in teaching about how ecologists and biologists use allometric relationships as well as teaching about the power function.

Assessment

The end-of-module questions can be used for assessment. The instructor version contains a pre-test.

References and Resources

The primary resource for this module is the Biopak software, available from the U.S. Forest Service and the H. J. Andrews Exeprimental Forest (operated jointly by Oregon State University and the U.S. For3est Service). The software is also available on the Web, here, with registration (accessed for the module on August 14, 2007).

This software consists of a DOS program (!) that can probe a database for relevant parameters about a variety of species of trees. The author of this module (Cole) has found it most useful to bypass the DOS program, and import the database from Biopak directly into a spreadsheet.

Another excellent article that addresses differences between amount of carbon stored in trees, and the rate of carbon storage (amounts versus rates)is: "Effects on Carbon Storage of Conversion of Old-Growth Forests to Young Forests," by Mark E. Harmon, William K. Ferrell, and Jerry F. Franklin, in Science, Vol. 247, No. 4943, (Feb. 9, 1990), pp. 699-702.

An excellent textbook dealing with nutrient cycles in forests, and providing excellent background for the processes of carbon uptake in forests is: Principles of Terrestrial Ecosystem Ecology by F.Sturart Chapin III, Pamaela A. Matson, and Harold A. Mooney, 2002, Springer Science+Business Media, Inc. ISBN 0-387-95443-0