This site requires Cookies enabled in your browser for login.
. . .
Alias List Editor
AOSM2022: Impacts of tall shrub expansion on the hydrological dynamics of a low-arctic catchment
Section 1: Publication
Authorship or Presenters
Cory Wallace, Evan Wilcox, Qianyu Chang, Anna Coles, Oliver Sonnentag, Philip Marsh, Aaron Berg, Jennifer Baltzer
Impacts of tall shrub expansion on the hydrological dynamics of a low-arctic catchment
Hydrology and Terrestrial Ecosystems
Cory Wallace, Evan Wilcox, Qianyu Chang, Anna Coles, Oliver Sonnentag, Philip Marsh, Aaron Berg, Jennifer Baltzer (2022). Impacts of tall shrub expansion on the hydrological dynamics of a low-arctic catchment. Proceedings of the GWF Annual Open Science Meeting, May 16-18, 2022.
AOSM2022 Northern Water Futures
Section 2: Abstract
Plain Language Summary
Shrub productivity and areal extent is increasing across much of the circumpolar arctic. Substantial focus has been placed on understanding the potential influence of this shrub expansion on global-scale surface energy balance feedbacks, including increased transport of water to the atmosphere, decreases in albedo, and changes to the carbon cycle. Much of our understanding of these processes has been informed by fine-scale studies, which document important impacts of shrub cover on hydrological conditions such as soil moisture, thaw depth, snow redistribution, and evapotranspiration. Despite this understanding, the cumulative effects of these local impacts have yet to be extended to hydrological responses at a regional or catchment scale.
Here we propose a conceptual model which considers the various hydrologically relevant ecosystem impacts of shrub expansion and generates specific hypotheses about how they may influence catchment-scale streamflow response to summer rainfall events. In particular, we expect increased shrub cover to increase evapotranspirative fluxes and interception, resulting in less total discharge and hydrographs with longer receding limbs. We test these hypotheses using time series of Normalized Difference Vegetation Index (NDVI), climatic variables, and streamflow responses collected from Trail Valley Creek, a watershed at the northern edge of the taiga-tundra ecotone of the Northwest Territories. As expected, maximum NDVI increased across much of the watershed, with 63% of pixels greening significantly from 2000 to 2019 and no pixels significantly browning. While both rainfall and discharge showed long term increases, the timing of these trends was inconsistent such that months showing increasing rainfall never displayed increasing streamflow. We propose that the lack of direct streamflow response to changing rainfall may be explained by shrub expansion across the basin. Our next steps are to test this by comparing individual storm responses in climatically similar years early and late in the time series to isolate the shrub response. Evidence of such a response would suggest shrub expansion may mediate future streamflow-climate relationships, complicating predictions of water resource availability in arctic systems.
Section 3: Miscellany
First Author: Cory Wallace, McMaster University
Additional Authors: Evan Wilcox, Wilfrid Laurier University; Qianyu Chang, Guelph University; Anna Coles, Government of the Northwest Territories; Oliver Sonnentag, Université de Montréal; Philip Marsh, Wilfrid Laurier University; Aaron Berg, University of Guelph; Jennifer Baltzer, Wilfrid Laurier University
Section 4: Download
T-2022-04-24-X1eKSyX3ozZ0X2JgVJxfrqKHQ Conference Publication 1.0