Gelisol

A Gelisol is an order in USDA soil taxonomy. Gelisols are soils that contain permafrost within two meters of the soil surface, or that show evidence of permafrost within one meter. Permafrost is soil, rock, or sediment that remains at or below 0°C (32°F) for at least two consecutive years.

Gelisols are typically found in high-latitude regions near the Arctic and Antarctic, as well as in high-altitude regions. These soils are characterized by slow rates of soil formation and decomposition due to the cold temperatures. Cryoturbation, the mixing of soil layers due to freezing and thawing, is a common process in Gelisols. This process can create distinctive features such as patterned ground (e.g., sorted circles, polygons).

The presence of permafrost significantly affects soil drainage, restricts root growth, and influences vegetation patterns. Organic matter accumulates on the surface of Gelisols because decomposition is slowed in the cold, waterlogged conditions. This often results in thick organic horizons.

Gelisols are relatively young soils, often having developed since the last glacial period. They are important in the global carbon cycle due to the large amounts of organic carbon stored in permafrost. As temperatures rise due to climate change, permafrost thaw can release this stored carbon into the atmosphere in the form of carbon dioxide and methane, potentially accelerating global warming.

Common characteristics of Gelisols include:

• Presence of permafrost
• Cryoturbation features
• Poor drainage
• Slow decomposition rates
• Accumulation of organic matter

Suborders of Gelisols include Histels, Turbels, and Orthels, which reflect differences in organic matter content, cryoturbation intensity, and other soil properties. Gelisols are important to understand in the context of climate change and the impacts of thawing permafrost on ecosystems and infrastructure.