Soil Physical, Hydraulic, and Thermal Properties in Interior Alaska, USA: Implications for Hydrologic Response to Thawing Permafrost Conditions

Abstract

Boreal forest regions are a focal point for investigations of coupled water and biogeochemical fluxes in response to wildfire disturbances, climate warming, and permafrost thaw. Soil hydraulic, physical, and thermal property measurements for mineral soils in permafrost regions are limited, despite substantial influences on cryohydrogeologic model results. This work expands mineral soil property quantification in cold regions through soil characterization from the discontinuous permafrost zone of interior Alaska, USA. Values extend beyond the range of prior measurement magnitudes in analogous regions, highlighting the importance of this data set. Rocky and silty upland soil landscape classifications and wildfire disturbance provided guiding frameworks for the sampling and analysis for potential implications for the hydrologic response to thawing permafrost. Bulk density (ρb), soil organic matter, soil‐particle size distributions (sand, silt, and gravel fractions), and soil hydraulic properties of van Genuchten parameters alpha and N had moderate evidence of differences between silty and rocky classifications. Burned and unburned sites had only moderate evidence of differences for silt fraction. Field‐saturated hydraulic conductivity (Kfs) was more variable at burned sites compared to unburned sites, which corresponded to observations of greater rooting depths at burned sites and observations of root paths in soil cores for Kfs measurement. Soil thermal properties suggested that gravel content may reduce the accuracy of commonly used estimation methods for thermal conductivity. This work provides soil parameter constraints necessary for hypothesis testing and site‐specific prediction with cryohydrogeologic models to examine controls on active layer and permafrost dynamics in upland boreal forests.

A Model of Ice Wedge Polygon Drainage in Changing Arctic Terrain

“…The anisotropy ratio K r /K z had somewhat erratic behavior, often appearing nearly isotropic, but with a range extending from 0.1 and 10. Similar values for hydraulic conductivity were published by [4,7,16,19,20], but these studies generally did not distinguish between K r and K z . Estimates by [8] for high-centered and low-centered polygons had generally similar magnitudes of K r .…”

“…The shape of the flow net is steady during the drainage period, while the magnitude of each local velocity vector declines with the depth of water in the center pool, as defined in Equation (20). Considering that each stream tube conducts identical discharge toward the periphery of the polygon, the flux magnitudes near the polygon center and the trough differ by orders of magnitude.…”

Generalized models to estimate carbon and nitrogen stocks of organic soil horizons in Interior Alaska

“…The mineral soil data presented here mostly represent the uppermost mineral soil. Ad-ditional examinations into bulk density and C concentrations of Alaskan mineral soil can be found in Ping et al (2010), Michaelson et al (2013), and Ebel et al (2019).…”

Generalized models to estimate carbon and nitrogen stocks of organic soil layers in Interior Alaska

“…However, the mineral soil data presented here do not represent full mineral soil profiles, since our sampling often stopped 5-10 cm into mineral soil. Additional examinations into bulk density and C concentrations of Alaskan mineral soil can be found in Ping et al (2010), Michaelson et al (2013, and Ebel et al (2019).…”