Cryoturbation

Cryoturbation by Brentwood Higman & Andrew Mattox

Cryoturbation refers to the process of frost action in soil science where the freezing and thawing cycles in periglacial environments cause the mixing or churning of soils, sediments, and other surface materials. This phenomenon is a significant aspect of permafrost and seasonally frozen ground areas, contributing to the unique patterns and structures observed in these cold ecosystems. Cryoturbation is a key factor in the development of certain soil horizons and plays a crucial role in the distribution of organic and inorganic material within the soil profile.

Mechanism

The primary mechanism behind cryoturbation involves the expansion of water as it freezes, which exerts a considerable force on the surrounding soil and rock particles. This process can lead to the vertical and lateral movement of materials, creating distinctive patterns such as frost heave and ice wedge polygons. The intensity and extent of cryoturbation are influenced by several factors, including soil moisture content, soil texture, the presence of vegetation, and the temperature fluctuations typical of the environment.

Types of Cryoturbation

Cryoturbation can be classified into several types based on the patterns and features it creates:

• Frost Heaving: The upward movement of soil particles caused by the expansion of freezing water in the soil.
• Frost Creep: A slower form of movement where soil particles are gradually pushed up and outwards on slopes due to the freeze-thaw cycles.
• Gelifluction: Occurs in areas with a thin active layer above permafrost, where the soil becomes saturated and flows downhill during the thaw season.
• Solifluction: Similar to gelifluction but occurs in environments without permafrost, where waterlogged soil flows over an impermeable layer.

Impact on Ecosystems

Cryoturbation significantly impacts ecosystem dynamics, particularly in Arctic and sub-Arctic regions. It affects seed dispersal, plant colonization, and the distribution of nutrients within the soil, thereby influencing vegetation patterns and biodiversity. Additionally, cryoturbation can alter the hydrology of cold environments by changing soil permeability and water retention capabilities.

Challenges and Research

Studying cryoturbation poses several challenges, primarily due to the remote and harsh conditions of periglacial environments. However, understanding this process is crucial for predicting the impacts of climate change on permafrost regions. As permafrost thaws, increased cryoturbation could lead to more significant carbon release from the soil, exacerbating global warming. Research in this field focuses on modeling cryoturbation processes and their interactions with global climate systems.

See Also

• Periglacial processes
• Soil science
• Climate change in the Arctic