Evaporation dominates evapotranspiration on Alaska’s Arctic Coastal Plain

The dynamics of evapotranspiration (ET), such as the partitioning to evaporation and transpiration, of polygonal ground on the Arctic Coastal Plain are not well understood. We assessed ET dynamics, including evaporation and transpiration partitioning, created by microtopographic features associated...

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Bibliographic Details
Published in:Arctic, Antarctic, and Alpine Research
Main Authors: Young-Robertson, Jessica M, Raz-Yaseef, Naama, Cohen, Lily R, Newman, Brent, Rahn, Thom, Sloan, Victoria, Wilson, Cathy, Wullschleger, Stan D
Format: Article in Journal/Newspaper
Language:unknown
Published: eScholarship, University of California 2018
Subjects:
Polygonal ground
permafrost
ice wedge
plant functional type
evapotranspiration partitioning
Physical Geography and Environmental Geoscience
Ecology
Antarctic and Alpine Research
Arctic
Ice
wedge*
Online Access:https://escholarship.org/uc/item/4mm5c6b2
https://escholarship.org/content/qt4mm5c6b2/qt4mm5c6b2.pdf
https://doi.org/10.1080/15230430.2018.1435931
Description
Summary:The dynamics of evapotranspiration (ET), such as the partitioning to evaporation and transpiration, of polygonal ground on the Arctic Coastal Plain are not well understood. We assessed ET dynamics, including evaporation and transpiration partitioning, created by microtopographic features associated with high- and low-centered polygons. Chamber ET and leaf-level transpiration measurements were conducted in one-week field campaigns in two growing seasons with contrasting weather conditions. We found that ET was greater in the drier and warmer sampling period (2013) compared to the colder and wetter one (2014). Evaporation dominated ET, particularly in the wetter and colder sampling period (>90% in 2014 vs. 80% in 2013). In the 2013 sampling period, wetter and warmer conditions increased ET and the contribution of transpiration to ET. If the soils warm with degrading permafrost, ET and the fraction contributed by transpiration may increase to a certain threshold, when moisture must increase with rising temperatures to further increase these fluxes. While the fraction of transpiration may rise with warmer soils, it is unlikely that transpiration will completely dominate ET. This work highlights the complexities of understanding ET in this dynamic environment and the importance of understanding differences across polygonal ground.

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