Geoscience Reference
In-Depth Information
Table 6.8
Classifi cation schemes for permafrost-a
f
fected soils
Person or country
Year
Approach
Main features
Tedrow, J.C.F.
1977
(
1968
,
1991
)
Genetic
Geographic - pedogenetic
gradients
Campbell, I.B. & Claridge,
G.G.C.
1987 (
1969
)
Genetic
Soil climate, weathering
stage
Canadian Soil
Classifi cation System
1998
Natural
Cryosolic (permafrost);
organic vs. mineral;
cryoturbation; soil properties
Russian Federation
(Fridland; Shiskov, etc.)
1982
Genetic
8 soil orders may have
permafrost; Cryozems all
contain permafrost, lack
diagnostic horizons
Soil Taxonomy
(USA)
2010 (
1999
)
Natural
Gelic materials w/
permafrost; organic vs.
mineral; cryoturbation;
diagnostic soil horizons
WRB for Soil Resources
2006
Natural
Cryic horizon (permafrost);
diagnostic soil horizons
Chinese Soil Taxonomic
System (Zhang & Gong)
2001
Natural
Subdivision of Primosols,
Gleyosols, Cambosols;
permafrost
cryosol subgroups in the Canadian system, and cryosol soil groups in the
WRB. Table
6.8
lists the cryosol classifi cation systems described herein.
6.3
Diagnostic Horizons in Cryosols
In
Soil Taxonomy
(ST) soils are classifi ed according to diagnostic horizons (epipe-
dons and subsurface horizons) and characteristics or properties that may be used for
mineral material, organic material, or both.
In ST Gelisols, which are analogous to cryosols in the Canadian and WRB sys-
tems, are defi ned on the basis of the presence of permafrost within 1 m of the sur-
face or the presence of gelic materials and permafrost within 2 m of the surface.
Despite these requirements, cryosols contain fi ve of the eight diagnostic epipedons
recognized in ST, including two organic horizons (folistic and histic) and three min-
eral horizons (mollic, umbric, ochric).
The folistic epipedon is an organic horizon that forms under unsaturated condi-
tions and must be more than 15 or 20 cm thick. Soils with folistic epipedon (Folistels
or folistic subgroups) occur on peat plateaus or mountains in Alaska and likely
occur elsewhere in the world. These soils are well-drained, have an udic soil-
moisture regime, and contain a layer of mossy or woody peat over mineral material
and/or permafrost. The histic epipedon is a thick organic horizon that forms under
saturated conditions. Soils with a histic epipdeon are recognized in the Histels
