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Glenna M. Malcolm
Department of Biology
Pennsylvania State University
From Prairies to Corn Fields for Fuel: A Tale of Lost Carbon

With increasing U.S. government support for biofuel production in the late 2000s came increased pressure to convert more land to cornfields for ethanol. To make way for more corn, millions of acres of prairie grassland were plowed under, destroying an extremely diverse wildlife habitat that also served as a large carbon reservoir. This case study focuses on the reasons for and consequences of large carbon losses when prairie grasslands are converted to agricultural lands. Many students are challenged when faced with linking together energy flows, decomposition, and nutrient cycles.  This case gives students the opportunity to consider different pools in the carbon cycle and the fluxes between them in order to model (on paper) an integrated picture of why carbon is lost when prairie grasslands are plowed and planted to cornfields.  Students also consider ways that carbon loss from land conversion due to ethanol production might be avoided via government incentive programs or mitigated via changes to farming practices. This case study was developed for an introductory ecology, environmental science, soil science, or agriculture course.

Unintended Consequences of Plant Domestication on Plant-Insect Interactions 

This case study investigates how plant domestication sometimes produces unintended consequences for plant-insect interactions. The narrative follows a boy in middle school, Podrick, who goes on a class field trip and notices that there are no caterpillar pests on the native sunflowers, in contrast to the farm on which his father grows domesticated sunflowers. When Podrick asks his teacher for an explanation, she agrees to do some research and report back the next day. The students in your course examine the research she finds and are tasked with formulating an answer in terms that Podrick can understand. In addition to offering teachers and students the opportunity to explore multi-trophic level interactions, students also work on writing hypotheses, interpreting data, integrating knowledge, and writing a clear and concise summary of results. This case is appropriate for introductory ecology, entomology, agriculture, or science education courses. Depending on how in-depth teachers want to go with statistics, the case might also be appropriate for similar upper level courses.