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Oecologia

, Volume 187, Issue 4, pp 1009–1023 | Cite as

Arctic plant ecophysiology and water source utilization in response to altered snow: isotopic (δ18O and δ2H) evidence for meltwater subsidies to deciduous shrubs

  • R. Gus Jespersen
  • A. Joshua Leffler
  • Steven F. Oberbauer
  • Jeffrey M. Welker
Special Topic

Abstract

Warming-linked woody shrub expansion in the Arctic has critical consequences for ecosystem processes and climate feedbacks. The snow–shrub interaction model has been widely implicated in observed Arctic shrub increases, yet equivocal experimental results regarding nutrient-related components of this model have highlighted the need for a consideration of the increased meltwater predicted in expanding shrub stands. We used a 22-year snow manipulation experiment to simultaneously address the unexplored role of snow meltwater in arctic plant ecophysiology and nutrient-related components of the snow–shrub hypothesis. We coupled measurements of leaf-level gas exchange and leaf tissue chemistry (%N and δ13C) with an analysis of stable isotopes (δ18O and δ2H) in soil water, precipitation, and stem water. In deeper snow areas photosynthesis, conductance, and leaf N increased and δ13C values decreased in the deciduous shrubs, Betula nana and Salix pulchra, and the graminoid, Eriophorum vaginatum, with the strongest treatment effects observed in deciduous shrubs, consistent with predictions of the snow–shrub hypothesis. We also found that deciduous shrubs, especially S. pulchra, obtained much of their water from snow melt early in the growing season (40–50%), more than either E. vaginatum or the evergreen shrub, Rhododendron tomentosum (Ledum palustre). This result provides the basis for adding a meltwater-focused feedback loop to the snow–shrub interaction model of shrub expansion in the Arctic. Our results highlight the critical role of winter snow in the ecophysiology of Arctic plants, particularly deciduous shrubs, and underline the importance of understanding how global warming will affect the Arctic winter snowpack.

Keywords

Alaska Tundra Ecohydrology Water sources δ18Arctic precipitation Photosynthesis Nitrogen δ13

Notes

Acknowledgements

This project was funded primarily by the National Science Foundation Arctic Observing Networks award #1504141 and made possible by a suite of earlier ITEX, NATEX, IPY-ITEX, and AON (0632184, 0856728, 0119279, 1433063, 1432982, 1504381) projects lead by J. M. Welker and S. F. Oberbauer. Datasets generated during this study are available in the NSF Arctic Data Center or upon request. We thank Jeremy Buttler and Hannah Puterbaugh for excellent field and lab assistance, Paddy Sullivan, Sean Cahoon, John Ferguson, and Andy Anderson-Smith for generosity with their time and expertise on technical issues, Annie Brownlee and Eric Klein for guidance with sample processing and timely analysis of leaf tissue and water samples, Agata Buchwal for insightful discussion and generous field assistance, and the entire Toolik Field Station staff for an outstanding research experience. Finally, we thank five anonymous reviewers for their helpful comments on earlier versions of this manuscript.

Author contribution statement

JMW, AJL, and SFO formulated the idea. RGJ, JMW, and AJL developed methodology. RGJ collected the data. RGJ analyzed the data. RGJ, JMW, AJL, and SFO wrote the manuscript.

Supplementary material

442_2018_4196_MOESM1_ESM.docx (158 kb)
Supplementary material 1 (DOCX 157 kb)

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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  • R. Gus Jespersen
    • 1
  • A. Joshua Leffler
    • 2
  • Steven F. Oberbauer
    • 3
  • Jeffrey M. Welker
    • 4
    • 5
  1. 1.Department of Biological SciencesUniversity of Alaska AnchorageAnchorageUSA
  2. 2.Department of Natural Resource ManagementSouth Dakota State UniversityBrookingsUSA
  3. 3.Department of Biological SciencesFlorida International UniversityMiamiUSA
  4. 4.UArctic, Ecology and Genetics Research UnitUniversity of OuluOuluFinland
  5. 5.University of Alaska AnchorageAnchorageUSA

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