Abstracts

The territory of Republic of Altai is characterized by a large variety of relief forms, with well-pronounced vertical forest belts as well as by rich flora. In this respect, of particular interest is the southern region of Priteletskaya taiga wherein in 1956 A.V.Kuminova has found a formation of cedar-forest with an abundance of relict species of tertiary vegetation, named as the Kyginski refugium and positioned in the valley of the Kyga river and its tributary Bayas. Thanks to nearness of the lake aquatory in combination with protection against cold winds by massifs, the Kyga river valley is remarkable for the warmest and mildest climate in the whole South Siberia, with average annual temperature above +4°C.

Highly productive, so-called “primeval” cedar-forests of different age (of 3-4 generations), with no effect exerted by forest fires and another catastrophic phenomena for many centuries, have come into being on fertile soils. Some gigantic trees are more than 500 years old, 1.5 m across and 40-45 m high. Almost every year they produce cone yields and that is indicative of optimum ecological conditions for cedar growth.

The development of vigorous herbaceous soil-covering under forest canopy rules out any nutcrackers activity as to seeds distribution, therefore, reforestation goes on, mainly, owing to the seeds of trees growing nearby. This factor contributes to a formation of biogroups (families) of closely related individuals, with transpollination being favourable to inbreeding. Phenological and physical isolation of the populations of cedar-forests growing in valleys rules out almost fully the possibility of megastrobile pollination by pollen of another stands. The above-mentioned factors are conducive to an increase in the level of trees homozygosis in population, including recessives.

Empty seeds are formed in uniting recessive lethals, controlling embryogenesis, in homozygotes, resulting in a large percent (18-32% and even 65% and 100% in some trees) of empty seeds in cones of trees growing in the “primeval” cedar-forests.

Thus, there are two opposite processes observable therein. On the one hand, favourable ecological conditions contribute to manifestation of genetic diversity expressed in phenotypic polymorphism, on the other hand, close transpollination leads to narrowing of genetic diversity. The study of the said processes is of great theoretical and practical importance for selection of Siberian cedar.

Note. Abstracts are published in author's edition

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