Cryosol

Soil profile of a Turbic Cryosol

Cryosol is a reference soil assembly from the World Reference Base for Soil Resources (WRB). Cryosols are characterized by permafrost , which means that the subsoil is permanently frozen and only the topsoil thaws every summer. Cryosols are defined by the diagnostic cryic horizon . This is characterized by a massive layer of ice or clearly visible ice crystals. If the water content is lower, it is defined by a temperature <0 ° C for at least two years. Seasonal thawing and freezing often result in cryoturbation, i.e. a strong mixing of the near-surface horizons. Equally typical are the incorporation of organic matter into the soil as wellFrost elevation with subsequent grain size sorting . This leads, among other things, to stone rings or, on inclined surfaces, to stone strips and solifluction . As a result of global warming, more and more permafrost is permanently thawing . As a result, the organic material in the cryosol is mineralized and carbon dioxide and methane are released into the atmosphere . This leads to an intensification of the greenhouse effect .

distribution

Cryosols occur only in regions with permafrost conditions . They are the dominant soil type in the polar and subpolar zones and are common as a companion soil type in the boreal zone (mostly under coniferous forests) and in the high mountains. In total, they currently cover around 18 million km² and thus around 13% of the earth's surface.

Web links

• Profile photos (with classification) WRB homepage
• Profile photos (with classification) IUSS World of Soils

literature

• IUSS Working Group WRB: World Reference Base for Soil Resources 2014, Update 2015. World Soil Resources Reports 106, FAO, Rome 2015. ISBN 978-92-5-108369-7 ( PDF 2.3 MB).
• W. Zech, P. Schad, G. Hintermaier-Erhard: Soils of the world. 2nd Edition. Springer Spectrum, Heidelberg 2014. ISBN 978-3-642-36574-4 .
• W. Amelung, H.-P. Blume , H. Fleige, R. Horn, E. Kandeler , I. Kögel-Knabner , R. Kretschmar, K. Stahr , B.-M. Wilke: Scheffer / Schachtschabel textbook of soil science. 17th edition. Heidelberg 2018. ISBN 978-3-662-55870-6 .