title: Water uptake of Alaskan tundra evergreens during the winter-spring transition.
abstract: OBJECTIVE
  The cold season in the Arctic extends over 8 to 9 mo, yet little is known about vascular plant physiology during this period. Evergreen species photosynthesize under the snow, implying that they are exchanging water with the atmosphere. However, liquid water available for plant uptake may be limited at this time. The study objective was to determine whether evergreen plants are actively taking up water while under snow and/or immediately following snowmelt during spring thaw.
  
  
  METHODS
  In two in situ experiments, one at the plot level and another at the individual species level, (2)H-labeled water was used as a tracer injected beneath the snow, after which plant stems and leaves were tested for the presence of the label. In separate experiments, excised shoots of evergreen species were exposed to (2)H-labeled water for ∼5 s or 60 min and tested for foliar uptake of the label.
  
  
  RESULTS
  In both the plot-level and the species-level experiments, some (2)H-labeled water was found in leaves and stems. Additionally, excised individual plant shoots exposed to labeled water for 60 min took up significantly more (2)H-label than shoots exposed ∼5 s.
  
  
  CONCLUSIONS
  Evergreen tundra plants take up water under snow cover, some via roots, but also likely by foliar uptake. The ability to take up water in the subnivean environment allows evergreen tundra plants to take advantage of mild spring conditions under the snow and replenish carbon lost by winter respiration.
authors.affiliation: Department of Biological Sciences, Florida International University 11200 SW 8th Street, Miami, Florida 33199 USA.
authors.forename: Jonathan G
authors.initials: JG
authors.lastname: Moser
authors.affiliation: Department of Biological Sciences, Florida International University 11200 SW 8th Street, Miami, Florida 33199 USA oberbaue@fiu.edu.
authors.forename: Steven F
authors.initials: SF
authors.lastname: Oberbauer
authors.affiliation: Department of Biology, University of Miami, 215 Cox Science Center, 1301 Memorial Drive, Coral Gables, Florida 33124-0421 USA.
authors.forename: Leonel da S L
authors.initials: Lda S
authors.lastname: Sternberg
authors.affiliation: Department of Biology, University of Miami, 215 Cox Science Center, 1301 Memorial Drive, Coral Gables, Florida 33124-0421 USA.
authors.forename: Patrick Z
authors.initials: PZ
authors.lastname: Ellsworth
authors.affiliation: Department of Biological Sciences, University of Alabama, Box 870344, Tuscaloosa, Alabama 35487 USA.
authors.forename: Gregory
authors.initials: G
authors.lastname: Starr
authors.affiliation: Dauphin Island Sea Laboratory, 101 Bienville Boulevard, Dauphin Island, Alabama 36528 USA.
authors.forename: Behzad
authors.initials: B
authors.lastname: Mortazavi
authors.affiliation: Department of Biological Sciences, Florida International University 11200 SW 8th Street, Miami, Florida 33199 USA.
authors.forename: Paulo C
authors.initials: PC
authors.lastname: Olivas
mesh_terms: D019684:Magnoliopsida / Q000378:metabolism*; D018515:Plant Leaves / Q000378:metabolism; D018517:Plant Roots / Q000378:metabolism; D012621:Seasons; D012914:Snow; D013696:Temperature; D065929:Tundra; D014867:Water / Q000378:metabolism*
chemical_list: D014867:Water
keywords: Toolik Field Station; cold season; deuterium; evergreen; frozen soil; permafrost; snow cover; stable isotope; tundra; water uptake