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Extreme Yellowstone Flooding is Focus of Research by Idaho State University Ecologists

May 25, 2023

aerial photo of Lamar River

How portions of the Yellowstone National Park ecosystem responded to last year’s historic flooding is the focus of a new research project by Idaho State University stream ecologists.

Recently, Colden Baxter, professor in the Department of Biological Sciences, was awarded $100,000 to study how the 1 in 500-year extreme flooding event in June 2022 impacted streams in the headwaters of the Yellowstone and Lamar Rivers. Funded by the National Science Foundation’s Rapid Response Research program, Baxter and his doctoral student, Jeremy Brooks, will be measuring the abundance and diversity of the fish and insects like mayflies and midges that call the streams and the riparian ecosystems along their banks home. 

“While these floods can be devastating for our roads, bridges, and homes, it is unclear exactly how stream and riparian ecosystems will respond,” said Baxter. “The current thought among scientists is that when an extreme disturbance - like a flood or fire - happens, these ecosystems will experience a hard reset. Yet, past research from Yellowstone following the extreme fires of 1988 showed that the Yellowstone ecosystem is resilient to - and may even benefit from - such extreme disturbances. As the climate of our region continues to change rapidly, rain-on-snow events like the one we had in 2022 will become more common and, as a result, we can expect more extreme disturbances like the event in Yellowstone in the coming years.”

Researchers wade through a river

Baxter says they’ will wrap up the first phase of the project in the fall of 2023, during which they will collect field samples from Yellowstone. From there, Brooks will lead the sample processing and data analysis.

“Our preliminary observations suggest that the extreme flood impacted the stream and riparian ecosystems, but by no means were they reduced to a blank slate,” said Brooks. “Rather, it appears that some members of these ecological communities were winners while others were losers.”

The research expands on a multi-year research project funded by the National Science Foundation in the same area that was just completed by Baxter and his students, as well as the subject of Brooks’ dissertation. From 2018 to 2021, the team investigated how changes in riparian plant communities, partly driven by the restoration of gray wolves, influenced stream and riparian ecosystems. The 2023 study sees them repeating many of the same measurements they conducted previously. 

“Contrary to the common mantra that ‘wolves saved the rivers of Yellowstone,’ we found that each of the stream and riparian ecosystems studied was unique and hosts distinct communities of microbes, invertebrates, fishes, birds, bats, and spiders,” said Brooks. “The sites with recovered willows, partially and indirectly connected to the restoration of wolves, were not necessarily more diverse or supporting larger populations than sites without willows, but they were considerably different. So rather than ‘saving rivers,’ we found the restoration of wolves and other top predators contributed to complexity across Yellowstone that otherwise would not have been there.” 

“When considered as a whole, the Yellowstone and Lamar Rivers ecosystems can act like a well-diversified investment portfolio. In the face of extreme disturbances, such as last year’s flood, some parts of the portfolio may lose out while others remain neutral or benefit,” Baxter explained. “Ecosystems like those found in Yellowstone, which retain their historical suite of native species and habitat-forming processes that lead to a ‘well-diversified portfolio,’ may be resilient to extreme, climate-change-induced disturbances. Conversely, ecosystems that have lost portions of their native species or been impacted by humans may not be as resilient to extreme events. Together, these two studies point to the importance of conserving native species and the complexity and connectivity of natural environments when managing for the resiliency of our region’s ecosystems to climate change.”  

The research is being conducted jointly with collaborators from Oregon State University and under Yellowstone National Park Permit YELL-2023-SCI-8070. In addition to their research activities, the scientists will be working with the National Park Service to create public education and outreach materials to share with communities that live with and depend on the Greater Yellowstone Ecosystem.

For more information on the ISU’s Department of Biological Sciences, visit isu.edu/biology

Prospective students can schedule a campus tour at isu.edu/visit


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