A study including work from a Manchester University professor reveals how climate and hydrothermal activity have shaped the vegetation, wildfire and aquatic ecosystem history of the Yellowstone Plateau over the past 15,000 years.
The results of the National Science Foundation-funded project were published this week in the journal Proceedings of the National Academy of Sciences.
Sabrina Brown, assistant professor of biology and environmental studies at Manchester University, has spent the last decade conducting research in the Greater Yellowstone Ecosystem. Her interest in Yellowstone National Park’s Lower Geyser Basin began in 2020 when she analyzed sediment samples from Goose Lake, noticing alongside coauthors Cathy Whitlock and Chris Schiller that its contents differed from those in lakebeds in other parts of the park, suggesting that distinct geologic factors may have influenced the lake’s evolution.
Collaborators on the project included scientists from Montana State University, the U.S. Geological Survey, Oregon State University, Manchester University and Colorado State University.
In this study, the team collected core samples from small lakes of different ages in the Lower Geyser Basin, which is Yellowstone’s largest geyser system. The lakes are closed, meaning that they have no inflowing or outflowing streams.
Pollen records from the lakes indicate that after the ice receded, a grassy steppe ecosystem developed on the rhyolite volcanic soils. Steppe was replaced by a lodgepole pine forest that established between 12,800 and 11,000 years ago. Despite subsequent changes in climate, these pine forests have changed little in composition, leading the authors to suggest that lodgepole pine will continue to dominate the vegetation on the plateau even as the climate continues to warm in the future.
The team realized the importance of both geology and climate in explaining the environmental history of the geyser basin when the lake records were compared with high-resolution paleoclimate model results for Yellowstone. For example, the model showed that summers in the geyser basin were warmer and drier than today’s between 12,000 and 6,000 years ago, an observation that matched the charcoal evidence for more fires and the diatom records for lower lake levels then.
Sediments in the Lower Geyser Basin lakes reveal that Yellowstone’s hydrothermal systems were more active in the past during wet periods than dry ones, suggesting that future warming in Yellowstone may result in reduced hydrothermal activity, as well as increased wildfire incidence.
Research geophysicist Michael Poland, scientist-in-charge of the USGS Yellowstone Volcano Observatory, said such changes likely won’t be noticeable on the timescale of a human lifetime, though the study does point to interesting possibilities for near-term changes in the timing, force and frequency of geysers in Yellowstone’s hydrothermal areas.
“This study and ones like it help to give us a sense of what might be expected in the future for hydrothermal activity given current trends in climate,” he said. “That’s always been a key aspect of geology, and these sorts of studies show the past is the key to the present, which is then the key to the future. The more we understand past conditions and what drove them, the more we understand what’s likely to occur in the future.”
Edited from text by Diana Setterberg. MSU News Service.
