Gelisol Soil of the Permafrost

Gelisol Definition From Latin gelare meaning “to freeze” Gelisols must meet one of two criteria: 1) Permafrost within 1 meter of the soil surface OR 2) Evidence of cryoturbation within 1 meter of soil surface and permafrost within 2 meters of the soil surface As Pat said last week , gelisols are a relatively new soil order. Gelisols became recognized as a soil order in 90’s. Before that, Gelisols were identified as pergelic (have a mean annual temp below 0C) subgroups of Entisols, Inceptisols, Histosols, Mollisols, and Spodosols. Also called cryosols in the FAO/UNESCO system.

Permafrost Any type of ground that has been continuously frozen for at least two years Image: Eli Keene, The Arctic Institute Permafrost, the defining feature of the gelisol. Permafrost is simple any type of ground that has been continuously frozen for at least two year.

Cryoturbation aka frost churning mixing of soil due to freezing and thawing Cryoturbation is another important feature of gelisols. Cryoturbation (frost mixing) is an important process in many Gelisols and results in irregular or broken horizons, involutions, organic matter accumulation on the permafrost table. This is cause by mixing of soil due to freezing and thawing and the interaction between the two frozen fronts, the permafrost and the seasonally frozen soil. At 0 C, the volume of water expands at roughly 9%.

Gelisol Location Gelisols are found in very cold climates High latitude polar regions Localized high elevation areas

Global Coverage of Gelisols Approximately 9% of global ice-free land area (

US Coverage of Gelisols US Gelisols are only found in Alaska. US Coverage of Gelisols Approx. 8.7% of US ice-free land area, all located in Alaska.

Soil Factors/Characteristics CLIMATE Pergelic temperatures (mean annual temp of 0˚C) year round. Arid and effective precipitation Frozen climate results in extremely slow decomposition of organic material allowing the soil to accumulate high amounts of organic material and carbon. ORGANISMS Vegetation: lichens, mosses, grasses, and sedges Nematodes, aerobic and anaerobic bacteria, methanotrophs, fungi RELIEF Contributes to freezing/ thawing processes Climate is the dominate factor in soil formation of gelisols. The annual mean temperature of gelisols is at or below 0C. And gelisols typically have a range od effective precipitation, but are also present in arid climate. Vegetation in gelisols include very hardy grasses and sedges, mosses, lichens and sometime larger trees and shrubs in the willow (Salix), birch (betula), and spruce (picea). Up until the early 2000’s there was this idea of a biological zero, a temperature around 5C, in which no significant biological activity took place, but research has shown that there are organisms that are active in the permafrost soils.

Soil Formation Factors PARENT MATERIAL Can form in any parent material Often glacial drift material TIME Climate drastically slows soil formation processes Many gelisol soils are millions of years old Climate is the dominate factor in soil formation of gelisols. The annual mean temperature of gelisols is at or below 0C. And gelisols typically have a range od effective precipitation, but are also present in arid climate. Vegetation in gelisols include very hardy grasses and sedges, mosses, lichens and sometime larger trees and shrubs in the willow (Salix), birch (betula), and spruce (picea). Up until the early 2000’s there was this idea of a biological zero, a temperature around 5C, in which no significant biological activity took place, but research has shown that there are organisms that are active in the permafrost soils.

Examples of common cryostructures: (a) lenticular structures visible below 30-40 cm in a freshly exposed profile of an earth hummock, Mould Bay, Arctic Canada (reprinted by permission, ASA, CSSA, SSSA); (b) lenticular structures transition to a reticulate structure at 130-150 cm in a core extracted from the center of a low-centered ice-wedge polygon; (c) lenticular structure; and (d) suspended (ataxitic) structure. 

Gelisol Suborders Histels: Turbels: Orthels: High amounts of organic material Found in low lying or wet areas Turbels: Evidence of cryoturbatiton Irregular/distorted horizons Orthels: Other gelisols that are not highly organic or well mixed Histels are the Gelisols with large amounts of organic carbon that commonly accumulate under anaerobic conditions, or the organic matter at least partially fills voids in fragmental, cindery, or pumiceous materials. Cold temperatures contribute to the accumulation of organic matter. Turbels are the Gelisols that have one or more horizons with evidence of cryoturbation in the form of irregular, broken, or distorted horizon boundaries, involutions, the accumulation of organic matter on top of the permafrost, ice or sand wedges, and oriented rock fragmentsTurbels are the dominant suborder of Gelisols. They account for about half the Gelisols on a global basis.

Suborder: HISTELS Organic soils similar to histosols 80% or more organic material from the soil surface to a depth of 50cm (or solid layer). Occur in subarctic and low artic regions

Suborder: TURBELS Dominant suborder of gelisols, over 50% of gelisols worldwide, found at 65˚N in middle and high arctic vegetation regions Over 1/3 of horizons are broken/distorted due to cryoturbation Accumulation of organic material on the permafrost layer Ice wedges are common

Suborder: ORTHELS 2nd most abundant suborder of gelisols Found in southern Andes and high latitudes of North America Dry compared to Histels and Turbels Little to no cryoturbation

Gelisol suborders

Soil horizon symbols jj - cryoturbation ff - permafrost Wfm – glacic horizon (>75% ground ice in a layer that is ≥ 30cm thick)

solifluction

Polygon formations in permafrost

Soil organic carbon content (SOCC)

Soil organic carbon content (SOCC)

Climate Change and Gelisols Warming (due to climate change) in high latitudes occurs faster than in lower latitudes Melting of the permafrost and gelisol soils will release enormous amounts of CO2 and methane into the atmosphere.

Sources: https://www.uidaho.edu/cals/soil-orders/gelisols https://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs142p2_0 51232.pdf https://web.archive.org/web/20040918224844/http://grunwald.ifas.ufl. edu/Nat_resources/soil_orders/gelisols.htm https://soilsmatter.wordpress.com/2017/09/01/what-are-alaskas-soils- telling-us/ Tarnocai, C., et al. 2009. Soil organic carbon pools in the northern circumpolar permafrost region. Global Biogeochemical Cycles. V23. https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2008GB003 327

Sources cont. https://colbydigssoil.com/2012/03/23/the-soil-orders-gelisols/ Ping, C., et al. 2015. Permafrost soil and carbon cycle. Soil Journal. file:///C:/Users/Jane/Downloads/Pingetal2015permafrostsoilscarboncy cling.pdf