ARCTIC Geomorphology, Vegetation Succession, Soil Characteristics and Permafrost in Retrogressive Thaw Slumps near Mayo, Yukon Territory

• Main Authors: C. R. Burn, P. A. Friele
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 1988
• Subjects: Arctic; Yukon; Ice; Mayo; permafrost
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.508.2740; http://pubs.aina.ucalgary.ca/arctic/Arctic42-1-31.pdf

ABSTRACT. Three retrogressive thaw slumps of varying age have been initiated by erosion of ice-rich glaciolacustrine sediments on a bend of Stewart River, 3 km upstream from Mayo, Yukon Territory. Two of the slumps are presently active; the third stabilized before 1944. The rate of retreat of the active slump headwalls between 1949 and 1987, determined from aerial photographs and ground surveys, is up to 16 m.yr". Floors of the active thaw slumps contain well-defined vegetation successional communities that are distinct from the local, mature boreal forest. Although a few clumps of mature forest vegetation survive the fall into the slump, a birch/white spruce sere, similar to the original forest, is re-established after a period of 35-50 years. Changes in soil calcium carbonate and soil structure profiles on disturbed surfaces of varying age demonstrate the initiation of pedogenesis in the floor of the stabilized slump, but assays of pH, organic carbon and total nitrogen indicate that after about 40 years the new soils remain immature. Comparison of ground temperatures in the stabilized thaw slump and at undisturbed sites in the area indicates that the ground thermal regime may return to local conditions a century or more after disturbance. Key words: permafrost, terrain disturbance, retrogressive thaw slump, vegetation succession, Yukon Territory RÉSUMÉ. Trois décrochements de fonte régressifs, datant de différentes époques, ont été formés àl'origine par l'érosion de sédiments glaciolacustres riches en glace, à un tournant de la rivière Stewart, à 3 km en amont de Mayo dans le Yukon. Deux des décrochements sont actuellement en activité, le troisième s'étant stabilisé avant 1944. La vitesse de recul des parois des décrochements actifs entre 1949 et 1987, déterminée a partir de photographies aériennes et d'études au sol, est de jusqu'à 16 m.an-l. Le sol des décrochements de fonte actifs contient une végétation bien définie de communautés successives qui sont distinctes de la forêt boréale adulte environnante. ...