Student-faculty duo publishes paper in national geophysics journal

The remains of a forest fire in the Oregon Cascade Range, approximately 15 years later. Photo by the Northwest Oregon Ecology Program, USDA Forest Service.


Senior Verena Joerger is a co-author of a paper published in an American Geophysical Union journal, along with assistant professor of environmental science Tom O’Halloran, who spearheaded the project.

The paper, titled “Post-fire influences of snag attrition on albedo and radiative forcing,” examines the environmental effects of a wildfire in a mature forest in the Oregon Cascade Range. Its findings challenge the notion that regrowth of vegetation after fire is what primarily controls the Earth’s reflectance, or albedo, within the burned area.

“It’s well known that forest fires can modify Earth’s climate because they release greenhouse gasses. Another thing they do is modify the brightness or reflectance of the Earth’s surface,” O’Halloran explains. “Scientists are interested to understand how quickly the land surface recovers after fire because of this influence on the climate. … We show in this paper that when a wildfire leaves a lot of standing dead trees, those dead trees — we call them snags — can actually be the most important element controlling the albedo of the land surface. In some cases it takes the trees decades to fall down, so this can have a long-term effect.”

O’Halloran began working on the project as a postdoctoral research associate with Dr. Bev Law at Oregon State University, where the project was partially funded by a grant from the Department of Energy. Collaborators from the National Park Service and U.S. Forest Service conducted the fieldwork at the burn site with partial support from the National Science Foundation. Joerger helped O’Halloran analyze satellite measurements of the fire and write the paper over the last two years.

“What is most fascinating to me about our findings is that they will have implications for climate modeling,” Joerger says. “As the Earth’s climate changes, models are used to help predict how the Earth will respond to these changes. We have shown that these models will need to include vegetation succession as well as snags to better represent what controls albedo after forest fires.”

Co-publishing a scientific paper as an undergrad is a pretty big deal, she says. When O’Halloran asked her to be his research assistant, she was only a sophomore.


Verena Joerger spent part of her summer climbing high above the tree line to help install Sweet Briar’s Land Atmosphere Research Station.


“I had a lot of catching up to do,” she admits. “I was given lots of scientific papers to read to help me understand, as well as get me started on a literature review.”

But Joerger proved to be a fast learner. Soon, she was performing regression analyses, creating graphs and analyzing datasets using Excel.

“I had never used Excel for much more than creating simple tables and graphs, so there was a bit of a learning curve,” she says.

Near the end of her time as a research assistant, O’Halloran gave her the opportunity to draft the introduction for the paper.

“I was nervous but excited to give it a shot,” she recalls. “I never thought I would get as involved in the research project as I did.”

Joerger also learned how to create, edit and submit the manuscript — all valuable skills as she looks toward graduate school. Being a research assistant and completing a summer internship have helped her narrow down what kind of environmental science she wants to focus on for her master’s, she says.

“I was able to winnow my interests down to forest ecology, atmospheric science and climate science,” she says. “I hope to attend graduate school next fall to study land-atmosphere interactions.”

The duo will present their research at the AGU’snational meeting in San Francisco, which takes place Dec. 15-19. Joerger will also give a presentation on her Honors Summer Research Project, which involved helping to install Sweet Briar’s Land Atmosphere Research Station.