Characterization of Gelolls in northern Alaska, USA

Mollisols are dark colored, carbon-rich mineral soils occupying a large proportion (836 soil series) of the soils of the Central Plains of the United States. By contrast, only eight official soil series of Mollisols have been mapped in Alaska (six Haplocryolls, one Calcicryoll, one Haplogeloll). Little information exists about Geloll pedogenesis, taxonomic variability, and extent. In this study, 39 horizons were morphologically described across ten Geloll pedons in northern Alaska. Based on analogous taxonomic structure in Cryolls, two pedons would meet the criteria for a Fluventic subgroup as the organic carbon content was ≥0.3% (1.47% and 0.88%) at a depth of 125 cm below the mineral soil surface. Three pedons would meet the criteria for a Pachic subgroup because the mollic epipedon was thicker than 40 cm (52 cm, 53 cm, and 54 cm) and the texture class was finer than loamy fine sand (sandy loam). However, no Fluventic or Pachic subgroups currently exist for Haplogelolls. Two pedons were classified as Cumulic Haplogelolls, and three pedons were Typic Haplogelolls. Field and laboratory characterization allowed for the development of a Geloll pedogenic concept generally represented by well-drained soils with limestone and/or dolomitic parent material. Such soils generally feature thin or no surficial organic horizons and large quantities of coarse fragments and coarse textured materials. Soil organic carbon calculations for suspected areas of Alaska Gelolls total 1.18 Pg; closely aligning with estimates of previous studies. Future work should expand the explanatory taxonomy based on new morphological expressions observed throughout gelic temperature regime regions.