Evaluation of the presence of streambed vegetation on storage and run‐off in hillslope streams in a High Arctic environment

Abstract

Polar Bear Pass, located on Bathurst Island (75°40′N, 98°30′W) in the Canadian High Arctic, is a large ecologically important, low-lying wetland that receives water inputs from streams in the surrounding hillslopes. Most of these hillslope streams are gravel-bed streams; however, some streambeds are moss lined. One of these vegetated streams was selected to determine how vegetation influences run-off processes (e.g. water storage and streamflow) in comparison with a similar-sized gravel-bed hillslope stream. During the 2009 and 2010 field seasons, snow cover, melt and streamflow measurements were collected in both streams. Frost table and soil moisture conditions were monitored weekly along four cross-sectional transects in each stream basin, and vegetation inventories were conducted in July 2010. The active layer developed more quickly in 2010 than in 2009, yet the thaw depth remained thinner in the vegetated stream in both years. In 2009, prolonged rainfall of low intensity and meltwater inputs from long-lasting valley snowbeds maintained streamflow. Warmer and drier conditions in 2010 caused the stream to eventually cease flow, only regenerating after intense rainfall. Moss plays an important role in modifying streamflow later in the season when low-flow conditions persist, acting as a barrier to streamflow as the moisture deficit of the vegetation must be satisfied before streamflow can regenerate. Results indicate that there is a threshold that determines whether vegetation promotes or hinders streamflow and that this factor will have important implications in response to changing climate conditions for this site and other arctic landscapes.

Snow cover variability at Polar Bear Pass, Nunavut

“…1 For previous years (2008)(2009)(2010), see Young and Labine (2010) and Miller and Young (2016). A photograph of the site can be found in Fig.…”

“…At the CAWS, hourly variables of air temperature (°C), relative humidity (%), net radiation (W/m 2 ), incoming and outgoing radiation (W/m 2 ), wind speed (m/s) and direction (degrees), precipitation (mm), and ground heat flux (W/m 2 ) were routinely monitored. Detailed information on instrumentation used in 2008 is reported in and from 2009 to 2010 in Miller and Young (2016). Supplementary Table S1 1 details equipment used in 2012-2013 and Fig.…”

Thermal Regime of High Arctic Tundra Ponds, Nanuit Itillinga (Polar Bear Pass), Nunavut, Canada

“…Thaw depth in ponds was measured by probing the ground with a metal rod (± 10 mm) twice a week near water wells early in the season and then weekly once ground thaw slowed, providing a means of assessing active layer development and re-freeze (i.e., 2008, 2009) (Abnizova et al, 2014). Climate data (e.g., air temperature) were obtained from the main automatic weather station located near the PBP cabin situated on the plateau above the wetland (see Young and Labine, 2010;Young et al, 2013;Miller and Young, 2016 for additional details on instrumentation, sensor siting, and frequency of monitoring). These data allowed us to examine the air temperature-pond response, and to place our results in context of the variable spring and summer conditions over several years at PBP, and in relation to the nearest government weather station at Resolute Bay (Qausuittuq),…”

Spatial and temporal dynamics of groundwater flow across a wet meadow, Polar Bear Pass, Bathurst island, Nunavut

“…The area is underlain by continuous permafrost and the maximum active layer can vary from 0.3 to 0.5 m in boggy ground and can exceed 1.0 m in drier polar desert and gravelly soils (Miller and Young, ). Most of the vegetation in the Pass can be classified as wet meadow (Sheard and Geale, , ) and typical plants include cotton grass ( Eriophorum scheuchzeri ), sedges ( Carex aquatilis ) and mosses ( Orthothecium chryseum , Tomenthypnum nitens ) (Miller and Young, ).…”

“…The area is underlain by continuous permafrost and the maximum active layer can vary from 0.3 to 0.5 m in boggy ground and can exceed 1.0 m in drier polar desert and gravelly soils (Miller and Young, 2016). Most of the vegetation in the Pass can be classified as wet meadow Geale, 1983a, 1983b) and typical plants include cotton grass (Eriophorum scheuchzeri), sedges (Carex aquatilis) and mosses (Orthothecium chryseum, Tomenthypnum nitens) (Miller and Young, 2016). In contrast, much of the hillslopes and uplands of Bathurst Island are characterised by polar desert species such as saxifrage (Saxifraga oppositifolia), dryas (Dryas integrifolia), arctic willow (Salix arctica) and lichen.…”