Breaking It Down: What Factors Control Microbial Decomposition Rates?

Author(s)

Brian M. Connolly, Gonzaga UniversityFollow
Nigel D'Souza, Gonzaga UniversityFollow
Naupaka Zimmerman, University of San Francisco
John Zobitz, Augsburg University

Author ORCID Identifier

Brian Connolly: http://orcid.org/0000-0001-7084-4311

Document Type

Lesson Plan

Abstract

Demonstrating and modeling changes in ecosystem processes in the laboratory classroom can be logistically difficult and expensive. This complexity often leaves little time for students to generate and test hypotheses. Yet, we must foster student understanding of how matter and energy move through ecosystems to develop an appreciation of how current ecosystems function and how human-mediated global change may alter ecosystem processes. In this lesson, we describe an adaptation of the Tea Bag Index (TBI) that provides students with an inexpensive, adaptable, and easily replicated method for testing how an ecosystem function (i.e., decomposition by microorganisms) alters carbon flow between two carbon pools (i.e., dead organic matter and the atmosphere). We outline the steps that small student research groups can take to develop testable research questions with an emphasis on how abiotic factors (e.g., temperature, moisture availability) can influence the rate of biomass loss. We outline the equipment and methods that can be used for conceptual add-ons (e.g., CO₂ gas analysis) and include exercises that work on teaching students principles of tidy data organizing and data analysis. Finally, we include rubrics for written and graph-based assignments and an example dataset to assist instructors in implementing the lab in their own courses. In post-lab evaluations, students reflected positively on this lab exercise in open-ended course evaluation prompts and we observed better quality data collection and analysis in subsequent experimental labs, likely motivated by the practice and guidelines provided in this lab module.

Publication Date

5-15-2024

Recommended Citation

Connolly BM, D’Souza N, Zimmerman N, Zobitz J. 2024. Breaking It Down: What Factors Control Microbial Decomposition Rates? CourseSource 11. https://doi.org/10.24918/cs.2024.17

Creative Commons License

This work is licensed under a Creative Commons Attribution-NonCommercial-Share Alike 4.0 International License.