Much attention has been given to questions of determining the size of the fungal population in permafrost samples. There are data on the fungi of North-West Territories (Canada), Alaska, and Russia. The age, depth, and chemical and textural composition of the samples varied considerably, due to the fact that samples were taken by different expeditions, each having its own set of goals and objectives. In general, however, the data on the fungal amount pertain to superficial Arctic horizons.
Recent studies (Kochkina et al. 2001; Ozerskaya et al. 2008) made it possible to derive a generalized picture of the amount of fungi in samples of differing age. There is almost no relation between the amount of fungi and the depth and age of permafrost; in samples of modern soil profiles, the existence of such a relation is judged from changes in the number of CFUs (Widden and Parkinson 1973; Soderstrom 1975; Mirchink 1988). Populations of fungi in permafrost samples are microfocal, in that increased numbers of CFUs may be detected in any portion of the sample, regardless of the depth or age of the sediments. This is the reason why the fungal amount varies over the range of four orders of magnitude, from less than 10 to almost 100,000 CFUs g-1 material. It is important to note that the peaks of numbers in individual foci are not paralleled by increased diversity of fungal species. Conversely, the ratio of the number of species to the total amount of fungal colonies (index of abundance; Odum 1971) in such cases dramatically decreases and tends to zero.
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