The role of water tracks in altering biotic and abiotic soil properties and processes in a polar desert in Antarctica

Abstract

Groundwater discharge via water tracks is a largely unexplored passageway routing salts and moisture from high elevations to valley floors in the McMurdo Dry Valleys (MDV) of Antarctica. Given the influence that water tracks have on the distribution of liquid water in seasonally thawed Antarctic soils, it is surprising how little is known about their role in structuring biotic and abiotic processes this cold desert ecosystem. Particularly, it is unclear how soil biota will respond to the activation of new water tracks resulting from enhanced active layer thickening or enhanced regional snowmelt. In the MDV, water tracks are both wetter and more saline than the surrounding soils, constituting a change in soil habitat suitability for soil biology and therefore the ecological processes they carry out. To investigate the net impact that water tracks have on Dry Valley soil biology, and therefore the ecosystem processes for which they are responsible, we analyzed microbial biomass and activity in soils inside and outside of three water tracks and relate this to the physical soil characteristics. Overall, our results suggest that water tracks can significantly influence soil properties, which can further impact biological biovolume and both biotic and abiotic fluxes of CO 2 . However, the nature of its impact differs with water track, further suggesting that not all water tracks can be regarded the same.

Water Tracks Enhance Water Flow Above Permafrost in Upland Arctic Alaska Hillslopes

“…Beneath the active layer, continuous permafrost acts as a barrier that impedes deeper subsurface flow (Ge et al, 2011;Walvoord et al, 2012). Conditions in water tracks differ significantly from those in their nontrack hillslope watersheds and are characterized by a deeper active layer depth, smaller amplitude of annual soil temperature change, coarser subsurface materials (Figure 1b), thicker snowpack, and higher soil moisture and nutrient contents (Ball & Levy, 2015;Curasi et al, 2016;Harms et al, 2019;Hastings et al, 1989;McNamara et al, 1999;Paquette et al, 2018;Rushlow, 2018). Since water tracks have a higher soil moisture content and are closer to their storage capacity than are the adjacent hillslopes, it has been suggested that water tracks are one of the main source areas for runoff to downslope rivers in response to summer rainfall (McNamara et al, 1997;Rushlow & Godsey, 2017) and spring snowmelt (Paquette et al, 2018).…”

“…Since water tracks have a higher soil moisture content and are closer to their storage capacity than are the adjacent hillslopes, it has been suggested that water tracks are one of the main source areas for runoff to downslope rivers in response to summer rainfall (McNamara et al, 1997;Rushlow & Godsey, 2017) and spring snowmelt (Paquette et al, 2018). Higher liquid-water saturation in water track soils is also linked to increased solute transport (Levy et al, 2011), nutrient and carbon cycling (Ball & Levy, 2015;Cheng et al, 1998;Harms & Ludwig, 2016;McNamara et al, 2008;Oberbauer et al, 1991;, vegetation productivity (Curasi et al, 2016), and heat transfer (Gooseff et al, 2013;Hastings et al, 1989;Paquette et al, 2016Paquette et al, , 2018.…”

Hillslope water tracks in the High Arctic: Seasonal flow dynamics with changing water sources in preferential flow paths

“…Water tracks have been the object of study mostly in Alaska and Antarctica, yet they have been reported in other parts of the periglacial domain, albeit sometimes under other terminologies (Curasi, Loranty, & Natali, ; Nicholson, ; Woo & Xia, ). Their importance in the periglacial landscape extends beyond that of a simple hydrological pathway, as they play specific roles in heat transfer and active layer development (Gooseff et al, ; Hastings, Luchessa, Oechel, & Tenhunen, ; Levy & Schmidt, ; Paquette, Fortier, Mueller, Sarrazin, & Vincent, ; Paquette, Fortier, & Vincent, ), solute transport (Levy, Fountain, Gooseff, Welch, & Lyons, ), and nutrient and carbon cycling (Ball & Levy, ; Cheng et al, ; Mcnamara, Kane, Hobbie, & Kling, ; Oberbauer, Tenhunen, & Reynolds, ). They also play a role in the development of the landscape, acting as an immature drainage network (Mcnamara, Kane, & Hinzman, ), as moisture provider for slow mass wasting processes (Verpaelst, Fortier, Kanevskiy, Paquette, & Shur, ), or as indications of denudation by leaching of fine material (Paquette et al, ).…”

Biotic Interactions in Experimental Antarctic Soil Microcosms Vary with Abiotic Stress

“…For example, elevated solar radiation and episodic warming has altered liquid water availability through melted buried ice, higher stream flows, expanded stream margins, and the formation of shallow groundwater transports, e.g., water tracks [16]. When water reaches previously dry soils, it liberates and mobilizes soil nutrients and salts, weathers soil, and stimulates primary productivity, significantly altering soil properties that affect soil biota [17][18][19]. Greater hydrological connectivity through the formation of more abundant streams and water tracks is predicted for the future [20], and could alter soil habitats and their biodiversity landscape-wide.…”