title: Deciduous trees are a large and overlooked sink for snowmelt water in the boreal forest.
abstract: The terrestrial water cycle contains large uncertainties that impact our understanding of water budgets and climate dynamics. Water storage is a key uncertainty in the boreal water budget, with tree water storage often ignored. The goal of this study is to quantify tree water content during the snowmelt and growing season periods for Alaskan and western Canadian boreal forests. Deciduous trees reached saturation between snowmelt and leaf-out, taking up 21-25% of the available snowmelt water, while coniferous trees removed <1%. We found that deciduous trees removed 17.8-20.9 billion m(3) of snowmelt water, which is equivalent to 8.7-10.2% of the Yukon River's annual discharge. Deciduous trees transpired 2-12% (0.4-2.2 billion m(3)) of the absorbed snowmelt water immediately after leaf-out, increasing favorable conditions for atmospheric convection, and an additional 10-30% (2.0-5.2 billion m(3)) between leaf-out and mid-summer. By 2100, boreal deciduous tree area is expected to increase by 1-15%, potentially resulting in an additional 0.3-3 billion m(3) of snowmelt water removed from the soil per year. This study is the first to show that deciduous tree water uptake of snowmelt water represents a large but overlooked aspect of the water balance in boreal watersheds.
authors.affiliation: U.S. Geological Survey, Alaska Science Center, Anchorage, Alaska, USA.|International Arctic Research Center, University of Alaska, Fairbanks, Alaska, USA.
authors.forename: Jessica M
authors.initials: JM
authors.lastname: Young-Robertson
authors.affiliation: International Arctic Research Center, University of Alaska, Fairbanks, Alaska, USA.
authors.forename: W Robert
authors.initials: WR
authors.lastname: Bolton
authors.affiliation: Department of Atmospheric Sciences, Geophysical Institute, University of Alaska, Fairbanks, Alaska, USA.
authors.forename: Uma S
authors.initials: US
authors.lastname: Bhatt
authors.affiliation: Geophysical Institute and Institute of Northern Engineering, University of Alaska, Fairbanks, Alaska, USA.
authors.forename: Jordi
authors.initials: J
authors.lastname: Cristóbal
authors.affiliation: NOAA National Weather Service, Fairbanks, Alaska, USA.
authors.forename: Richard
authors.initials: R
authors.lastname: Thoman
mesh_terms: D000413:Alaska; D002170:Canada; D002980:Climate; D018515:Plant Leaves; D045483:Rivers; D012621:Seasons; D012987:Soil; D066188:Taiga; D014197:Trees; D014867:Water / Q000032:analysis*
chemical_list: D012987:Soil; D014867:Water