Next-Generation Ecosystem Experiments – Arctic

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Characterized by vast amounts of carbon stored in permafrost, Arctic tundra is rapidly evolving as permafrost degrades in response to a changing climate. The mechanisms responsible for this system-wide reorganization have been unpredictable and difficult to isolate because they are initiated at very fine spatial scales, and because of the large number of interactions among the individual system components. To address this challenge, the Terrestrial Ecosystem Science program within the Department of Energy’s Office of Biological and Environmental Research is supporting a next-generation ecosystem experiments (NGEE) project in the Arctic.

Landscapes in Transition. A mechanistic understanding of what controls the coupled nature of hydrology, biogeochemistry, and vegetation dynamics is needed for system-wide prediction of permafrost dynamics. NGEE–Arctic research activities are designed to identify and quantify the mechanisms underlying processes that control carbon and energy transfer in the Arctic biosphere, as well as how those processes play out in a changing Arctic landscape.

Geomorphological features—including thaw lakes, drained thaw lake basins, and ice-rich polygonal ground—provide the organizing framework for integrating process studies and observations from the pore or core scale (micron to tens of centimeters) to plot (meters to tens of meters) and landscape (kilometers) scales. Within these discrete geomorphological units, mechanistic studies in the field and laboratory are targeting four critical and interrelated components—water, nitrogen, carbon, and energy dynamics—that determine whether the Arctic is, or in the future will become, a negative or positive feedback to anthropogenically forced climate change. Multiscale research activities organized around these components include hydrology and geomorphology, vegetation dynamics, biogeochemistry, and energy transfer processes.

Permafrost Landscapes

Permafrost Landscapes. Degradation of ice-rich permafrost causes subsidence and increased variability in topography across the Arctic landscape. Associated changes in hydrology, vegetation, and biogeochemistry create “hot spots” (i.e., locations within an ecosystem that exert a disproportionately large influence on the flow and processing of nutrients) for CO2 and CH4 fluxes.

This comprehensive suite of NGEE–Arctic process studies and observations is being strongly linked to model development and application requirements for improving process representation, initializing multiscale model domains, calibrating models, and evaluating model predictions. The overall objective is general knowledge and understanding through direct observation and fine-grained simulation of Arctic tundra ecosystems and the mechanisms that regulate their form and function. Specifically, this generalization will provide improved representation of Arctic tundra states and dynamics in the land model component of a coupled Earth system model.

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