It has been studied the influence of winter freezing glacial forms produced in the profiles of gray forest soils on the structure and micromorphology of their genetic horizons. The soils were sampled in autumn, winter, and spring. The structure and soil fabric were studied in sections and frozen ground samples. When preparing the sections from the frozen samples, the ice was substituted for resin that allowed to examine the microstructures of soil genetic horizons being in a frozen state.

The genetic horizons have been established to differ significantly on the bulk of ice and its forms. The ice was more abundant in horizon A, in which a great variety of glacial forms was observed. The ice was presented here as small separate crystals, their aggregates, and lenses. Under effect of forming ice the shift and moving of separate soil microaggregates, aggregates and particles of larger sizes took place; some elements of microstructure were regrouped. New planes and parking voids appeared; the former ones changed their sizes and configuration. The ice crystals generated in decomposing plant remains caused their active mechanical breakage, separation displacement of small fragments. The forms of ice crystals and larger ice formations refine the conformation and sizes of soil aggregates, microaggregates and separate microzones.

With a change into alluvial horizons the variety glacial forms decreases. In horizons B1 and B2, ice formations are dominant as small lenses or ice streaks. They are observed in planes of separate structures, parking voids. The ice often fills separate voids completely. It also can be found in the voids where living roots or their decomposing remains are present. No significant effect of the forming ice on rearrangement of micromorphology of the lower frozen horizons of the profile has been found.

Dr. Stanislav Gubin
Institute of Soil Sciences and Photosynthesis
Moscow District
142292 Pushchino RUSSIA
E-mail: sotnikov@issp.serpukhov.su