Hostname: page-component-586b7cd67f-dlnhk Total loading time: 0 Render date: 2024-11-24T12:41:15.370Z Has data issue: false hasContentIssue false
  • English
  • Français

Synthesis of studies of palsa formation underlining the importance of local environmental and physical characteristics

Published online by Cambridge University Press:  20 January 2017

Matti Seppälä
Matti Seppälä*
Affiliation:
Department of Geosciences and Geography, University of Helsinki, Finland
*
E-mail address:[email protected]
Get access Rights & Permissions [Opens in a new window]

Abstract

This review presents a synthesis of four decades of palsa studies based on field experiments and observations mainly in Fennoscandia, as well as laboratory measurements. Palsas are peat-covered mounds with a permanently frozen core; in Finnish Lapland, they range from 0.5 to 7 m in height and from 2 to 150 m in diameter. These small landforms are characteristic of the southern margin of the discontinuous permafrost zone. Palsa formation requires certain environmental conditions: long-lasting air temperature below 0°C, thin snow cover, and low summer precipitation. The development and persistence of their frozen core is sensitive to the physical properties of peat. The thermal conductivity of wet and frozen peat is high, and it decreases significantly as the peat dries and thaws. This affects the development of the active layer and makes its response to climate change complex. The insulating properties of dry peat during hot and dry summers moderate the thawing of the active layer on palsas. In contrast, humid and wet weather during the summer causes deep thawing and may destroy the frozen core of palsas. Ice layers in palsas have previously been interpreted as ice segregation features but because peat is not frost-susceptible, the ice layers are now reinterpreted as resulting from ice growth at the base of a frozen core that is effectively floating in a mire.

Keywords

PermafrostThermal conductivityActive layerCyclic developmentSnow depthPalsaBuoyancy
Type
Research Article
Information
Quaternary Research , Volume 75 , Issue 2 , March 2011 , pp. 366 - 370
Copyright
University of Washington

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Åhman, R. Palsar I Nordnorge. Meddelanden från Lunds Universitets Geografiska Institution. Avhandlingar 78, (1977). 1–165.Google Scholar
An, W., and Allard, M. A mathematical approach to modelling palsa formation: insights on processes and growth conditions. Cold Regions Science and Technology 23, (1995). 231–244.Google Scholar
Allard, M., and Rousseau, L. The internal structure of a palsa and a peat plateau in the Rivière Boniface region, Québec: inferences on the formation of ice segregation mounds. Géographie physique et Quaternaire 53, (1999). 373–387.Google Scholar
Brown, R.J.E. Influence of Vegetation on Permafrost. Proceedings Permafrost International Conference November 1963, Lafayette, Indiana. National Academy of Science—National Research Council. (1966). Publication, Washington, D.C. 20–25. 1287 Google Scholar
Brown, R.J.E. Occurrence of Permafrost in Canadian Peatbogs. Proceedings of the Third International Peat Conference, Ottawa. National Research Council of Canada. (1968). 174–181.Google Scholar
Fortier, R., and Aubé-Maurice, B. Fast Permafrost Degradation Near Umiujag in Nunavik (Canada) since 1957 Assessed from Time-lapse Aerial and Satellite Photographs. Proceedings of the Ninth International Conference on Permafrost. University of Alaska Fairbanks. Vol. 1. (2008). 457–462.Google Scholar
Fries, T., and Bergström, E. Några iakttagelser öfver palsar och deras förekomst i nordligaste Sverige. (Some observations of palsas and their occurrence in northernmost Sweden). Geologiska Föreningen i Stockholm Förhandlingar 32, (1910). 195–205.Google Scholar
Haeberli, W. Die Basis Temperatur der winterlichen Schneedecke als möglicher Indicator für die Verbreitung von Permafrost in den Alpen. Zeitschrift für Gletscherkunde und Glazialgeologie 9, (1973). 221–227.Google Scholar
Kershaw, G.P., and Gill, D. Growth and decay of palsas and peat plateaus in the Macmillan Pass-Tsichu River area, Northwest Territories, Canada. Canadian Journal of Earth Sciences 16, (1979). 1362–1374.CrossRefGoogle Scholar
Kujala, K., Seppälä, M., and Holappa, T. Physical properties of peat and palsa formation. Cold Regions Science and Technology 52, (2008). 408–414.Google Scholar
Lundqvist, G. En palsmyr sydost om Kebnekaise. Geologiska Föreningen i Stockholm Förhandlingar 73, (1951). 209–225.Google Scholar
Lundqvist, J. Patterned ground and related frost phenomena in Sweden. Sveriges Geologiska Undersökning, ser. C583, (1962). 1–101.Google Scholar
Lundqvist, J. Earth and ice mounds: a terminological discussion. Péwé, T.L. The Periglacial Environment: Past and Present. (1969). McGill-Queen's University Press, Montreal. 203–215.Google Scholar
Luoto, M., and Seppälä, M. Modelling the distribution of palsas in Finnish Lapland with logistic regression and GIS. Permafrost and Periglacial Processes 13, (2002). 17–28.Google Scholar
Luoto, M., and Seppälä, M. Thermokarst ponds as indicator of the former distribution of palsas in Finnish Lapland. Permafrost and Periglacial Processes 14, (2003). 19–27.CrossRefGoogle Scholar
Luoto, M., Fronzek, S., and Zuidhoff, F.S. Spatial modelling of palsa mires in relation to climate in northern Europe. Earth Surface Processes and Landforms 29, (2004). 1373–1387.CrossRefGoogle Scholar
Matthews, J.A., Dahl, S.-O., Berrisford, M.S., and Nesje, A. Cyclic development and thermokarstic degradation of palsas in the mid-alpine zone at Leipulan, Dovrefjell, southern Norway. Permafrost and Periglacial Processes 8, (1997). 107–122.3.0.CO;2-Z>CrossRefGoogle Scholar
Outcalt, S.I., and Nelson, F. Computer simulation of buoyancy and snow-cover effects in palsa dynamics. Arctic and Alpine Research 16, (1984). 259–263.CrossRefGoogle Scholar
Payette, S., Delwaide, A., Caccianiga, M., and Beauchemin, M. Accelerated thawing of subarctic peatland permafrost over last 50 years. Geophysical Research Letters 31, 18 (2004). 1–4.CrossRefGoogle Scholar
Railton, J.B., and Sparling, J.H. Preliminary studies on ecology of palsa mounds in northern Ontario. Canadian Journal of Botany 51, (1973). 1037–1044.Google Scholar
Rönkkö, M., and Seppälä, M. Surface Characteristics Affecting Active Layer Formation in Palsas, Finnish Lapland. Permafrost. Proceedings of the Eight International Conference on Permafrost, Zurich, Switzerland. Volume 2. (2003). 995–1000.Google Scholar
Seppälä, M. The term ‘palsa’. Zeitschrift für Geomorphologie, N.F. 16, (1972). 463 CrossRefGoogle Scholar
Seppälä, M. Seasonal thawing of a palsa at Enontekiö, Finnish Lapland, in 1974. Biuletyn Peryglacjalny 26, (1976). 17–24.Google Scholar
Seppälä, M. An experimental study of the formation of palsas. Proceedings Fourth Canadian Permafrost Conference, Calgary. National Research Council of Canada, Ottawa. (1982). 36–42.Google Scholar
Seppälä, M. Seasonal Thawing of Palsas in Finnish Lapland. Permafrost Fourth International Conference Proceedings. (1983). National Academy Press, Washington, D.C. 1127–1132.Google Scholar
Seppälä, M. The origin of palsas. Geografiska Annaler A68, (1986). 141–147.CrossRefGoogle Scholar
Seppälä, M. Palsas and related forms. Clark, M.J. Advances in Periglacial Geomorphology. (1988). John Wiley, Chichester. 247–278.Google Scholar
Seppälä, M. Depth of snow and frost on a palsa mire, Finnish Lapland. Geografiska Annaler A72, (1990). 191–201.CrossRefGoogle Scholar
Seppälä, M. Snow depth controls palsa growth. Permafrost and Periglacial Processes 5, (1994). 283–288.Google Scholar
Seppälä, M. How to make a palsa: a field experiment on permafrost formation. Zeitscrift für Geomorphologie N.F. Supplement-Band 99, (1995). 91–96.Google Scholar
Seppälä, M. Relief control of summer wind direction and velocity: a case study from Finnish Lapland. Norsk Geografisk Tidsskrift—Norwegian Journal of Geography 56, (2002). 117–121.Google Scholar
Seppälä, M. Surface abrasion of palsas by wind action in Finnish Lapland. Geomorphology 52, (2003). 141–148.Google Scholar
Seppälä, M. Wind as a Geomorphic Agent in Cold Climates. (2004). Cambridge University Press, Cambridge. 358 Google Scholar
Seppälä, M., and Kujala, K. The role of buoyancy in palsa formation. Knight, J., and Harrison, S. Periglacial and Paraglacial Processes and Environments. Geological Society Special Publication 320, (2009). 57–69.Google Scholar
Sollid, J.L., and Sørbel, L. Palsa bogs as a climate indicator—examples from Dovrefjell, southern Norway. Ambio 27, (1998). 287–291.Google Scholar
Špolanskaya, N.A., and Evseyev, V.P. Domed-hummocky peatbogs of the northern taiga in western Siberia. Biuletyn Peryglacjalny 22, (1973). 271–283.Google Scholar
Vallée, S., and Payette, S. Collapse of permafrost mounds along a subarctic river over last 100 years (northern Québec). Geomorphology 90, (2007). 162–170.Google Scholar
Washburn, A.L. Permafrost features as evidence of climatic change. Earth-Science Reviews 15, (1980). 327–402.Google Scholar
Washburn, A.L. Palsas and continuous permafrost. Proceedings of the Fourth International Conference on Permafrost 1, (1983). 1372–1377.Google Scholar
Washburn, A.L. What is a palsa?. Abhandlungen der Akademie der Wissenschaften in Göttingen, Mathematisch-Physikalische Klasse 35, (1983). 34–47.Google Scholar
Yoshikawa, K., and Hinzman, L.D. Shrinking thermokarst ponds and groundwater dynamics in discontinuous permafrost near Council, Alaska. Permafrost and Periglacial Processes 14, (2003). 151–160.Google Scholar
Zoltai, S.C. Palsas and peat plateaus in central Manitoba and Saskatchewan. Canadian Journal of Forest Research 2, (1972). 291–302.Google Scholar
Zuidhoff, F.S., and Kolstrup, E. Changes in palsa distribution in relation to climate change in Laivadalen, northern Sweden, especially 1960–1997. Permafrost and Periglacial Processes 11, (2000). 55–69.Google Scholar