Geoscience Reference
In-Depth Information
Chapter 10
Alpine Cryosols
10.1
Introduction
This chapter focuses on cryosols that exist in areas with mountain permafrost. China
contains the largest area with alpine permafrost, including the Qinghai-Tibet Plateau
and portions of the Himalayas, Tien Shan, and Karakoram Mountains, at 2.1 million
km
2
, which constitutes 45 % of the total area with alpine permafrost (Table
10.1
,
Fig.
10.1
). Russia contains the next largest area of mountain permafrost, including
the Caucasus, Urals, Sayan-Stoblovoi Mountains and portions of the Altai
Mountains at 581,000 km
2
, followed by Mongolia, Canada, and the USA. However,
as will be seen, only half of the alpine permafrost area contains cryosols, because
the active layer is deeper than 1 or 2 m in many of these soils.
10.2
Soil-Forming Factors
10.2.1
Climate, Permafrost, and Active-Layer Depths
The elevation at which mountain permafrost is reported in the literature ranges from
as low as 500 m (by defi nition; Gorbunov
1978
) in high-latitude environments such
as Iceland and the subpolar portions of the Caucasus Mountains to >5,000 m in mid-
latitude regions such as the central Andes, Himalayas, and the Qinghai-Tibet Plateau
(Table
10.2
). The active-layer thickness ranges from >0.5 m in high-latitude moun-
tain environments such as Iceland or Greenland to more than 8 m in the Andes,
European Alps, and Altai Mountains.
Permafrost may exist in mountains where the mean annual air temperature (MAAT)
is as warm as 1.4 °C, but a value of −3 °C or lower is more typical of areas containing
mountain permafrost (Lewkowicz and Ednie
2004
; Etzelmüller et al.
2007
; Gruber
2012
). A MAAT of −5 or −6 °C may be necessary for the active layer to be within
