Synopsis of the Experiment

Principal Ecological Question Addressed
What Happens
Lab Objectives
Equipment/Logistics Required
Summary of What is Due
Keyword Descriptors

Principal Ecological Question Addressed

How do environmental factors influence the rate of CO₂ emission from soil?

What Happens

Before the lab meets, students read about decomposition, the global carbon cycle, and how the experimental chambers work. At the first lab session in small groups they collaboratively design their own experiment that will examine the influence of a single environmental factor on the rate of CO₂ emission from soil. They then conduct the experiment (which involves a 24 to 48 hour incubation in the field). The following week in lab students measure final weights of soda lime, they use a t-test to statistically analyze their results, and as homework write a draft lab report and then a final lab report.

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Experiment Objectives

At the end of this lab exercise students will be able to:

Explain how environmental factors, such as soil characteristics and microclimate, can affect soil CO₂ emission
Use the scientific method appropriately to answer a question, including generating hypotheses, designing an experiment, and statistically analyzing data.
Clearly communicate scientific results in writing and in the appropriate format

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Equipment/Logistics Required

Drying oven (105ºC)
Analytical balance (reads to 0.001 g)
30 small glass jars with lids (40 to 100 mL)
Desiccator
Soda lime
Aluminum weighing dishes
Clipboards
20 to 40 Rubbermaid^TM 3-L Cylinders or 2-L Bowls
Soil thermometers (or digital thermometers with metal probes)
pH meter (optional)
An experimental site where chambers can be left out overnight where they won’t be disturbed or vandalized

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Summary of What is Due

An Experimental Design written by student groups
A formal, 8 to 12 page Lab Report (2 drafts) written by individuals

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Keyword Descriptors

Ecological Topic Keywords:

carbon dioxide, abiotic factors, biogeochemical cycles, biophysical ecology, biotic factors, carbon cycle, climate change, decomposition, ecological services, ecosystems, ecosystem function, forest ecology, grasslands, greenhouse effect, global warming, microorganisms, slope effects, soil carbon, temperature

Science Methodological Skills Developed:

collecting and presenting data, data analysis, experimental design, field work, formulating hypotheses, graphing data, hypothesis generation and testing, identify biotic-abiotic interactions, library research, quantitative data analysis, quantitative sampling, scientific writing, soil moisture analysis, statistics, use of primary literature, use of spreadsheets, writing lab reports

Pedagogical Methods Keywords:

bounded inquiry, cooperative learning, formal groupwork, group work assessment, guided inquiry, inquiry, open-ended inquiry, peer evaluation, project-based teaching, rubric, prime trait assessment

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