Spotlight: Fire Science and Student Choice

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Collecting ash in the meadow

In the years we’ve been teaching student programs, one of the most creative set of student projects came from an A.P. Environmental Science class at San Francisco University High School. During an overnight field trip to Donner Summit to study wetland water chemistry, the class encountered an unexpected phenomenon and drastically changed gears on their research projects.

At the time of the program, the King Fire (nearly 100,000 acres) had just recently been contained; the fire had encroached to within 15 miles of Donner Summit. The intense winds from the fire had blown ash high enough into the atmosphere that it had rained down onto the meadow students were investigating.

Going into the program, the plan was for students to study water quality (pH, total dissolved solids, water flow, and temperature) and how these factors may correlate with populations of plants, insects, or amphibians in the wetland. The atypical experience of seeing ash everywhere during the first field day was a difficult phenomenon to ignore, so students ran with it.

Standing amidst a meadow coated in a layer of ash, students grouped together and brainstormed several questions they had about the ash deposition. Most of their questions fell into the category of trying to figure out what, if any, impact the ash might have on the meadow. The class split up into four research groups tackling different sub questions: “How much ash has fallen in the meadow?” “How does this ash affect water pH in the meadow?” “What effect does fire ash have on soil pH?” “How does the effect of ash on soil pH vary with depth?”

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Students in the makeshift lab

Each group spent the next two days combing the meadow collecting ash fragments with an impressive level of focus. My experience as an instructor that day, has led me to believe this was largely because these ash related projects were their own idea. Because we instructors let them pivot their research projects toward this phenomenon, instead of trying to reign them back to the original plan, they were more engaged in their research.

The groups ran several transects across the meadow collecting and weighing ash across the field site. Back the lodge, they also conducted laboratory experiments of mixing different volumes of ash with water or soil to measure the impact it would have on pH levels. One of the neat things about this program was how the groups shared their data to better answer their original question of “What impact is the ash having on the meadow?” While they did find that ash could increase the pH of soil and water, based on their calculations they found that the levels of ash they observed in the meadow would not be large enough to cause a measurable increase in water pH. While I’ve seen the null hypothesis be disappointing to students many times, these students were rightfully proud of their findings. In only three days, they had observed a unique phenomenon, asked relevant questions about it, collected data, and discovered answers to their questions.

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Fire ash can increase water pH

Below are links to the students’ original presentations. They serve as an example of the power of giving students the freedom to investigate topics they are excited about.

The effect of fire ash on soil pH

The amount of ash deposited in Van Norden Meadow

The effect of ash on soil pH at different soil depths and locations

The effect of fire ash deposition on wetland water pH