Freeze-Thaw Effects on Granular Structure Reorganization for Soil Materials of Varying Texture and Moisture Content

The effect of soil freezing on N cycling: comparison of two headwater subcatchments with different vegetation and snowpack conditions in the northern Hokkaido Island of Japan

“…One possibility is that soil freezing disrupts the tight coupling between NH 4 + production and subsequent nitriWcation (Pawluk 1988;Miller and Jastrow 1990). Though surviving nitriWers were able to produce NO 3 ¡ in soil subject to the short freezing episode observed in late November/ early December, their activity was could have been depressed when soil was subjected to prolonged freezing over the entire winter, such as in Shibecha 0 and 5 cm soil depths, compared to the same soil subjected to unfrozen (e.g., at Uryu) environments.…”

Permafrost soils and carbon cycling

“…Under snow cover, sublimation ice can build near the surface from water vapor in the soil atmosphere, and this can also produce needle ice. In this process, small amounts of surface-accumulated organic matter can be mixed with the top few centimeters of mineral soil -promoting aggregation, disrupting root establishment, and favoring biotic crust formation (Pawluk, 1988;Michaelson et al, 2008Michaelson et al, , 2012. In the High Arctic, where vegetative and snow cover are scant, a persistent net of soil surface cracks form due to freeze-desiccation contraction, creating small frost polygons that in turn produce microenvironments that support different vegetation communities .…”

Rates of Change of Soil Structure Under Different Cropping Systems

“…Pawluk (1988) has shown that repeated freezing and thawing of cores of glacial till clay loam results in the formation of granic and metafragmic microfabrics, whereas well-sorted lacustrine sediments tend to form banded fabrics. A distinctive type of banded fabric has also been observed in sandy seasonally frozen soils (Mermut and St. Arnaud, 1981).…”