Studying soil processes of the critical zone on the Vancouver campus

For Marc Kramer’s fall 2016 class called Soil Processes in the Earth’s Critical Zone, students found an outdoor laboratory just steps from their classroom.

Five students measured various aspects of the “critical zone,” where the bulk of the planet’s life forms reside. The critical zone is an enormously complex area stretching from the treetops, through soil to the groundwater and housing a vast array of interdependent biogeochemical processes. These processes have a huge hand in ecosystem services, such as clean water and air, as well as the fate of carbon, global warming’s fundamental element.

The WSU Vancouver campus sits amid a swatch of field and forest just east of the loop road. Open meadow at its edge, then a mix of deciduous and conifer forest sloping down to a stream, it offered a chance to take measurements related to several processes within the watershed—soil, water, trees and leafy matter, vegetation that falls from the trees. “It provides a nice snapshot,” said Kramer, an assistant professor of environmental chemistry.

“One of the many exciting things about the WSU Vancouver campus is you can literally walk outside the campus and have access to field sites that can be used in teaching,” Kramer said. It is not uncommon for students at other universities to have to drive 20 or even 30 minutes off-campus to reach field sites that can be used in course instruction.

An ideal learning context

The students’ aim was to identify soluble organic carbon and nitrogen response to seasonal, land-use and climate change in the Pacific Northwest. Last fall’s extraordinary rainfall provided the ideal context for analysis.

WSU Vancouver student researchers Corey Ruder and Sarah Kintner on site.

WSU Vancouver student researchers Corey Ruder and Sarah Kintner on site.

In the meadow, Sarah Kintner, a first-year master’s student from Green Bay, Wisc., collected water to test for dissolved organic carbon and nitrogen. In the woods, Corey Ruder, a doctoral student from near Sacramento, could measure changes in carbon-dioxide concentrations in and around the ground. Greg Clark, a first-year master’s student from Harrisburg, Pennsylvania, measured precipitation with instruments in the open meadow and under the canopy.

Luke Reyes, a doctoral student from New Jersey, patrolled litter traps, screens that caught leafy matter as it fell from the trees. He would dry the contents, weigh them and do carbon and nitrogen analyses to see how the vegetation is contributing inputs to the soil. And Geoff Kahl, a geology master’s student from Portland, sampled stream and groundwater to analyze their chemistry.

Kramer2

Doctoral student Luke Reyes collects tree litter to gauge carbon and nitrogen impact.

The students then developed indicators of how water arrives and moves through the system, plus measures of soil moisture, carbon, nitrogen and carbon dioxide. The next time the course is taught, students will be able to study the movement of metals and other mobile elements such as calcium or silicon, thanks to a recent large research grant from the Murdock foundation.

“The students will have access to new equipment—an inductively coupled plasma mass spectrometer and an ion chromatograph—that will allow them to measure many additional constituents in water,” Kramer said.

More rain, more intense storms?

Kramer encourages the students to answer the questions they started with but also to look for new questions that might arise from the data they chart. It’s science as a reality-based creative process.

While analysis continues, the students research in the course has already been making an impact. WSU’s Washington State Magazine published a story in its spring issue. In February, the students made a presentation to the WSU Vancouver faculty seminar and displayed a poster at the graduate student symposium. They will be presenting their results at the Ecological Society of America conference in Portland this summer. And they are writing a paper for publication.

By semester’s end, based on reading the scientific literature and analyzing their data, they had an interesting finding—that the carbon and nitrogen and water responses they observed during the heavy warm rains of this October provided a rare opportunity to gain insight into how future climates may impact soil processes. Their observations may well be a sign of things to come.

Predictions that climate change will bring increased rainfall have been around for a long time. “But no one knows what that means for life on the ground,” Reyes said. “We see evidence that the increased rainfall may come from more intense storms rather than more frequent storms. Our study provides a rare opportunity to better understand how water, dissolved carbon, and nitrogen may respond to these type of storms, which may well become the new norm.”

One of Kramer’s goals was to make field and lab-based measurements an integral part of the classroom experience. Not only does it provide practical experience, but it benefits the students in another way too. “Gathering so many pieces of data and working in a team, the students dramatically increase their capacity to do big science,” he said.

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