Speaker: Tamara Harms, Ph.D., Associate Professor, University of Alaska Fairbanks, Institute of Arctic Biology
Title: Permafrost Thaw and Changing Cycles of the Elements of Life
Abstract: Boreal and arctic ecosystems are undergoing rapid change, including more frequent fires, thawing permafrost, increasing temperature, and more extreme precipitation events. Though the effects of climate change on carbon emissions from high-latitude ecosystems are well documented, changes to cycles of nitrogen and phosphorus remain poorly understood, and may cause feedbacks to carbon emissions. My group studies the fate and transport of carbon and nutrients in arctic and boreal catchments. Using in situ studies of nutrient uptake, we have shown that nitrogen released from thawing permafrost is likely hydrologically exported from arctic catchments, whereas phosphorus is retained in soils. We are also developing metrics to establish stream chemistry as an indicator of ecological resilience and state changes in boreal catchments. Using high-frequency data collected by automated instream sensors, we have found surprising increases in nitrate concentration following rain in streams draining catchments where permafrost is likely thawing. Our research suggests large, climate-driven changes to the nitrogen cycle of high-latitude ecosystems, resulting in greater flux to downstream ecosystems.
Bio: Tamara Harms is an ecosystem ecologist and biogeochemist with interests in cycles of carbon, nitrogen, and phosphorus. She is an associate professor at the University of Alaska Fairbanks where she studies the effects of changing climate, hydrologic, and disturbance regimes on elemental cycles. She focuses on how hydrologic flowpaths mediate reaction and transport of materials and has worked in deserts, cities, and high-latitude ecosystems, all places where hydrologic connectivity is changing rapidly.
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For more information, contact Doris Switzer at dswitzer@gc.cuny.edu