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Freeze-thaw processes, temperature and moisture trends in earth hummocks
Kodríková, Anna ; Křížek, Marek (advisor) ; Treml, Václav (referee)
Earth hummocks are nonsorted patterned ground types. This thesis is primary focused on the study of temperature regime particularly during freeze-thaw process and also on factors that affect its non-uniformity. Secondary, it refers to the relation between temperature and moisture regime, morphometric characteristics of earth hummocks and their geographical expansion in the world. The information from the literature search is applied to the results from temperature and moisture measurements of the earth hummocks in depths 5 - 40 cm in the Hrubý Jeseník Mountains - Keprník peak in 2005 - 2010. The results show that many factors affect the non-uniformity of temperature regime in different parts of earth hummocks. The most important of them are: the shape of the earth hummock, the aspect orientation, the distribution and the height of snow cover, the wind exposure and the presence of vegetation. There is an interaction between the soil moisture content and the temperature regime, and they are mutually affected. The obtained results from the Keprník study area are compared with the literature data about the earth hummocks in the world. Key words: patterned ground, earth hummock, temperature regime, moisture, regelation, Keprník peak, Hrubý Jeseník Mountains
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Freeze-thaw processes, temperature and moisture trends in earth hummocks
Kodríková, Anna ; Křížek, Marek (advisor) ; Treml, Václav (referee)
Earth hummocks are nonsorted patterned ground types. This thesis is primary focused on the study of temperature regime particularly during freeze-thaw process and also on factors that affect its non-uniformity. Secondary, it refers to the relation between temperature and moisture regime, morphometric characteristics of earth hummocks and their geographical expansion in the world. The information from the literature search is applied to the results from temperature and moisture measurements of the earth hummocks in depths 5 - 40 cm in the Hrubý Jeseník Mountains - Keprník peak in 2005 - 2010. The results show that many factors affect the non-uniformity of temperature regime in different parts of earth hummocks. The most important of them are: the shape of the earth hummock, the aspect orientation, the distribution and the height of snow cover, the wind exposure and the presence of vegetation. There is an interaction between the soil moisture content and the temperature regime, and they are mutually affected. The obtained results from the Keprník study area are compared with the literature data about the earth hummocks in the world. Key words: patterned ground, earth hummock, temperature regime, moisture, regelation, Keprník peak, Hrubý Jeseník Mountains
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Hummock Grasses on the Mt. Keprník: Contribution to the Earth Hummocks Origin Discussion
Hrádek, Mojmír
Proofs submitted hitherto in evidence of earth hummocks cryogenic origin have been found as little probative. In presented poster, the attention was focused on the role of vegetation in hummocks origin. Some of hummocks are formed by dominant grass tussock with special habitus. Hummock grasses in the genus Carex sp., Eriophorium sp., resp. Juncus trifidi and Deschampsia sp. grow as an expanding dome, with green leaves in the centre and dead leaves at outer margin. Layer of dry leaves may be up to 5 cm thick and can serve as heat-insulation layer protecting frozen ground thawing in spring-time. Similar grass hummocks are typical not only for wind-swept alpine grasslands but also for low ranges and plains.
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