A studyincluding work from a 鶹ԭ professorreveals 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 鶹ԭ, has spent the last decade conducting research in the Greater Yellowstone Ecosystem.Her interest in Yellowstone National Park’s Lower Geyser Basinbegan in 2020when sheanalyzed sediment samples from Goose Lake, noticingalongside coauthors Cathy Whitlock and Chris Schillerthat 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.
Collaboratorson the projectincludedscientists fromMontana State University,theU.S. Geological Survey, Oregon State University,鶹ԭand Colorado State University.
Inthis study,the teamcollectedcore samples from small lakesof different agesin theLower Geyser Basin, which is Yellowstone’s largestgeyser system.The lakes are closed, meaning that theyhave noinflowing or outflowingstreams.
Pollen records from thelakesindicatethatafterthe ice receded, a grassysteppeecosystem developed onthe rhyolitevolcanic soils.Steppewas replaced byalodgepole pine forestthatestablishedbetween 12,800 and 11,000 years ago. Despitesubsequentchanges in climate,these pineforestshavechanged littlein composition, leading theauthors tosuggestthat lodgepole pine will continue to dominatethevegetation on the plateau evenas theclimate continues to warmin the future.
The teamrealized the importance ofbothgeology and climatein explaining theenvironmentalhistory of the geyser basinwhenthe lakerecordswere comparedwithhigh-resolutionpaleoclimatemodelresultsfor Yellowstone.For example,the model showed thatsummers in thegeyser basinwere warmer and drier thantoday’sbetween12,000 and6,000 years ago,an observation that matchedthe charcoal evidence for more firesand the diatomrecordsfor lower lake levelsthen.
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 likelywon’tbe noticeable on the timescale of a human lifetime, though the study does point tointeresting possibilitiesfornear-term changes inthe timing, force and frequency ofgeysers inYellowstone’s hydrothermalareas.
“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.”
Editedfrom text by Diana Setterberg. MSU News Service.
