1. Gelisol
Soil of the Permafrost

2. 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.

3. 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.

4. 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%.

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

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

7. 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.

8. 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.

9. 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.

12. Examples of common cryostructures: (a) lenticular structures visible below 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 cm in a core extracted from the center of a low-centered ice-wedge polygon; (c) lenticular structure; and (d) suspended (ataxitic) structure. 

14. 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.

15. 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

16. 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

17. 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

18. Gelisol suborders

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

22. solifluction

23. Polygon formations in permafrost

24. Soil organic carbon content (SOCC)

25. Soil organic carbon content (SOCC)

27. 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.

28. Sources: https://www.uidaho.edu/cals/soil-orders/gelisols
pdf
edu/Nat_resources/soil_orders/gelisols.htm
telling-us/
Tarnocai, C., et al Soil organic carbon pools in the northern circumpolar permafrost region. Global Biogeochemical Cycles. V

29. Sources cont.
Ping, C., et al Permafrost soil and carbon cycle. Soil Journal.
file:///C:/Users/Jane/Downloads/Pingetal2015permafrostsoilscarboncy cling.pdf