Теория температурного режима спячки сурков. [Theory temperature in hibernation marmots. Théorie de la température chez les marmottes en hibernation].

Résumé

TEMPERATURE REGIME OF MARMOT HIBERNATION THEORY K.I. Belovezhets People\'s Friendship University of Russia, Ecological Department: belovezhets@gmail.com Marmots hibernate in the layer of soil. Temperature regime of this environment corresponds to the temperature regime of the surface in terms of annual and diurnal temperature fluctuations and geographical gradients. Nevertheless, specific physical conditions of soil change well-known pattern of geographical and seasonal distribution of temperature. Temperature of ground depends on three main factors: surface temperature, underlying ground temperature and properties of soil. Surface temperature differs from air temperature due to process of consumption and reflection of solar energy and thus depends not only on insolation but on surface condi-tions as well. The soil\'s properties vary widely within the same geographical region providing diversity of possible habitats. Physical conditions of the ground are responsible for two main specific characteristics of temperature regime: decreasing and delaying of temperature fluctuations in depth. In natural habitats of marmots annual amplitude at the surface usually reaches several tens of degrees, at the depth of 2 m it is around 10-15°C, and less than 5°C at the depth of 4-5 m which is believed to be the average bottom depth for mar-mots\' burrows. Delay of annual temperature maximum at the depth of 2 m is around 1,5-2 months and almost half of year at the depth of 4-5 m. Thus, mar-mots start hibernation around temperature maximum at the depth of burrow and finish it around minimum. It allows using the most comfortable temperature conditions during year and annual minimum of temperature is expected to be one of the triggers finishing hibernation. Temperature of underlying soil layer can be constantly positive or nega-tive. According to this conditions all soils can be divided in two classes: sea-sonally frozen and seasonally melt. Seasonally frozen soils are typical for natural habitats of steppe marmot, Marmota bobak. Only shallow burrows of young animals, or normal hibernacula at the northern edge of range can face negative temperatures, but not regularly. Animals can avoid negative temperature during hibernation by choosing of appropriate habitat or by construction of a deeper burrow. On the other hand black-capped marmot, M. camtschatica inhabits area with mainly seasonally melted ground with permafrost above it. These marmots face negative temperature during hibernation permanently, they can only choose habitat with more or less long period of melted ground condition. Construction of deeper burrow is useless because of permafrost. So we can expect another complex of behavioral and physiological adaptations in comparison to steppe marmot. Situation is different for Mongolian marmot, M. sibirica. Mostly these marmots inhabit seasonally frozen soils, but at the northern edge of the area of distribution depths of frozen soil is more than bottom depth of marmots\' hibernacula. That means that at least in one part of its natural habitat M. sibirica faces negative temperatures during hibernation regularly. We can say that temperature niche of M. sibirica is wider than niches of M. bobak and M. camtschatica and it takes intermediate position.