The article analyzes the evolution of the oldest landscape-geographic school, which elements were founded by L. S. Berg, who based himself upon the ideas of V. V. Dokuchaev. Followers of L. S. Berg, adhering to the principle of continuation, were far from dogmatism and corporate illiberality, proceeding from acknowledgment of close connection between landscape doctrine and a. a. Grigoryev's ideas of geographical envelope, accepted the V. B. Sochava's notion of geosystems and other theoretical ideas. Leningrad school rejects the landscape science's closedness within the limits of just local peculiarities, giving it the important world-view value as a basement for learning the mutual relations between the society and geographical environment. A lot of attention is paid either to applied studies or to theoretical synthesis and making the cartographic and literary summaries on the landscape structure of both the Earth and our country.

The point of view is defended whereby the main object of geography is the correlation relationships that are limited to the certain spatial arena, have an interdisciplinary character and stay out of competence of partial fields of scientific knowledge. The dissimilar facts and processes that, according to N. N. Baransky, form the essence of geography («the core»), are associated by the author with cross-fertilization. It is geography, as the unique scientific matrix, that establishes the mo st complex mechanism of spatial interaction and correlation between the native and humanized nature.

The lakes with a surface area above 500 km in arctic, subarctic and taiga zone were selected. Total of 30 lakes has been considered: one in the Arctic zone, 9 in Subarctic and 20 in Taiga zone. Despite that the levels of lymnologic knowledge differed widely from lake to lake, there was educed the quite distinct dependence between the structure of lake's ecosystem and either factors related to latitude (climate, air and water temperature), or geology of catch basin and morphometry of lake bed. Lake's hydrochemical and hydrobiological regime is closely related to these factors, though the man impact, which is most frequent in Taiga zone, may disturb the natural indices of lake's condition and has been considered as well.