The microbiology of cryopedogenic soils of the subarctic with particular reference to the Churchill region

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Dular, Ram
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Soil materials taken from sampling sites in the Churchill and Inuvik areas were examined in an attempt to determine the role of various micro-organisms contributing to cryopedogenesis. Examination of the samples taken during September 1964 and 1965 included a critical study of the physico-chemical, microbiological and general biological characteristics. The findings suggest that soil development in the area is typical of that proceeding in other cryopedogenic regions in North America... These soils, further, are characterized as harbouring considerable population of bacteria, fungi and actinomycetes which, in general, tend to decrease abruptly (in a numberical sense) with depth. Soils are biologically active and are comparable to temperate soils in terms of their potential biological activity as determined by respiration intensity, mineralization of organic nitrogen and other enzymic activities... Microbial population in the areas consists mainly of cold-adapted native species similar in many respects to those forms prevalent in more temperate regions. Among the actinomycetes and fungi, the total number of genera encountered was low but, where present, these constituted a significant proportion of the total microbial population... A large number of quite different microbial isolates were found to be capable of growing under nitrogen-fixing conditions. Although they were mainly bacterial in type, some nitrogen-fixing species of fungi, yeasts and actinomycetes were noted. Counts of nitrogen-fixers ranged from several tens of thousands to several millions per gram of soil. The significance of these findings in terms of cryopedogenesis is discussed.