G. V. Frost


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Vegetation type is an important predictor of the arctic summer land surface energy budget
Jacqueline Oehri, Gabriela Schaepman‐Strub, Jin‐Soo Kim, Raleigh Grysko, Heather Kropp, Inge Grünberg, Vitalii Zemlianskii, Oliver Sonnentag, Eugénie Euskirchen, Merin Reji Chacko, Giovanni Muscari, Peter D. Blanken, Joshua Dean, Alcide di Sarra, R. J. Harding, Ireneusz Sobota, Lars Kutzbach, Elena Plekhanova, Aku Riihelä, Julia Boike, Nathaniel B. Miller, Jason Beringer, Efrén López‐Blanco, Paul C. Stoy, Ryan C. Sullivan, Marek Kejna, Frans‐Jan W. Parmentier, John A. Gamon, Mikhail Mastepanov, Christian Wille, Marcin Jackowicz-Korczyński, Dirk Nikolaus Karger, William L. Quinton, Jaakko Putkonen, Dirk van As, Torben R. Christensen, Maria Z. Hakuba, Robert S. Stone, Stefan Metzger, Baptiste Vandecrux, G. V. Frost, Martin Wild, Birger Ulf Hansen, Daniela Meloni, Florent Dominé, Mariska te Beest, Torsten Sachs, Aram Kalhori, A. V. Rocha, Scott Williamson, S. Crepinsek, A. L. Atchley, Richard Essery, Benjamin R. K. Runkle, David Holl, Laura D. Riihimaki, Hiroyasu Iwata, Edward A. G. Schuur, Christopher Cox, A. A. Grachev, J. P. McFadden, Robert S. Fausto, Mathias Goeckede, Masahito Ueyama, Norbert Pirk, Gijs de Boer, M. Syndonia Bret‐Harte, Matti Leppäranta, Konrad Steffen, Thomas Friborg, Atsumu Ohmura, C. Edgar, Johan Olofsson, Scott D. Chambers
Nature Communications, Volume 13, Issue 1

Abstract Despite the importance of high-latitude surface energy budgets (SEBs) for land-climate interactions in the rapidly changing Arctic, uncertainties in their prediction persist. Here, we harmonize SEB observations across a network of vegetated and glaciated sites at circumpolar scale (1994–2021). Our variance-partitioning analysis identifies vegetation type as an important predictor for SEB-components during Arctic summer (June-August), compared to other SEB-drivers including climate, latitude and permafrost characteristics. Differences among vegetation types can be of similar magnitude as between vegetation and glacier surfaces and are especially high for summer sensible and latent heat fluxes. The timing of SEB-flux summer-regimes (when daily mean values exceed 0 Wm −2 ) relative to snow-free and -onset dates varies substantially depending on vegetation type, implying vegetation controls on snow-cover and SEB-flux seasonality. Our results indicate complex shifts in surface energy fluxes with land-cover transitions and a lengthening summer season, and highlight the potential for improving future Earth system models via a refined representation of Arctic vegetation types.

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Disturbances in North American boreal forest and Arctic tundra: impacts, interactions, and responses
Adrianna C. Foster, Jonathan Wang, G. V. Frost, Scott J. Davidson, Elizabeth Hoy, Kevin W. Turner, Oliver Sonnentag, Howard E. Epstein, L. T. Berner, A. H. Armstrong, Mary Kang, Brendan M. Rogers, Elizabeth M. Campbell, Kimberley Miner, Kathleen M. Orndahl, Laura Bourgeau‐Chavez, David A. Lutz, Nancy H. F. French, Dong Chen, Jinyang Du, Tatiana A. Shestakova, J. K. Shuman, Ken D. Tape, Anna-Maria Virkkala, Christopher Potter, Scott J. Goetz
Environmental Research Letters, Volume 17, Issue 11

Abstract Ecosystems in the North American Arctic-Boreal Zone (ABZ) experience a diverse set of disturbances associated with wildfire, permafrost dynamics, geomorphic processes, insect outbreaks and pathogens, extreme weather events, and human activity. Climate warming in the ABZ is occurring at over twice the rate of the global average, and as a result the extent, frequency, and severity of these disturbances are increasing rapidly. Disturbances in the ABZ span a wide gradient of spatiotemporal scales and have varying impacts on ecosystem properties and function. However, many ABZ disturbances are relatively understudied and have different sensitivities to climate and trajectories of recovery, resulting in considerable uncertainty in the impacts of climate warming and human land use on ABZ vegetation dynamics and in the interactions between disturbance types. Here we review the current knowledge of ABZ disturbances and their precursors, ecosystem impacts, temporal frequencies, spatial extents, and severity. We also summarize current knowledge of interactions and feedbacks among ABZ disturbances and characterize typical trajectories of vegetation loss and recovery in response to ecosystem disturbance using satellite time-series. We conclude with a summary of critical data and knowledge gaps and identify priorities for future study.


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Shallow soils are warmer under trees and tall shrubs across Arctic and Boreal ecosystems
Heather Kropp, M. M. Loranty, Susan M. Natali, Alexander Kholodov, A. V. Rocha, Isla H. Myers‐Smith, Benjamin W Abbot, Jakob Abermann, E. Blanc‐Betes, Daan Blok, Gesche Blume‐Werry, Julia Boike, A. L. Breen, Sean M. P. Cahoon, Casper T. Christiansen, Thomas A. Douglas, Howard E. Epstein, G. V. Frost, Mathias Goeckede, Toke T. Høye, Steven D. Mamet, J. A. O’Donnell, David Olefeldt, Gareth K. Phoenix, V. G. Salmon, A. Britta K. Sannel, Sharon L. Smith, Oliver Sonnentag, Lydia Smith Vaughn, Mathew Williams, Bo Elberling, Laura Gough, Jan Hjort, Peter M. Lafleur, Eugénie Euskirchen, M.M.P.D. Heijmans, Elyn Humphreys, Hiroyasu Iwata, Benjamin M. Jones, M. Torre Jorgenson, Inge Grünberg, Yongwon Kim, James A. Laundre, Marguerite Mauritz, Anders Michelsen, Gabriela Schaepman‐Strub, Ken D. Tape, Masahito Ueyama, Bang-Yong Lee, Kirsty Langley, Magnus Lund
Environmental Research Letters, Volume 16, Issue 1

Abstract Soils are warming as air temperatures rise across the Arctic and Boreal region concurrent with the expansion of tall-statured shrubs and trees in the tundra. Changes in vegetation structure and function are expected to alter soil thermal regimes, thereby modifying climate feedbacks related to permafrost thaw and carbon cycling. However, current understanding of vegetation impacts on soil temperature is limited to local or regional scales and lacks the generality necessary to predict soil warming and permafrost stability on a pan-Arctic scale. Here we synthesize shallow soil and air temperature observations with broad spatial and temporal coverage collected across 106 sites representing nine different vegetation types in the permafrost region. We showed ecosystems with tall-statured shrubs and trees (>40 cm) have warmer shallow soils than those with short-statured tundra vegetation when normalized to a constant air temperature. In tree and tall shrub vegetation types, cooler temperatures in the warm season do not lead to cooler mean annual soil temperature indicating that ground thermal regimes in the cold-season rather than the warm-season are most critical for predicting soil warming in ecosystems underlain by permafrost. Our results suggest that the expansion of tall shrubs and trees into tundra regions can amplify shallow soil warming, and could increase the potential for increased seasonal thaw depth and increase soil carbon cycling rates and lead to increased carbon dioxide loss and further permafrost thaw.