Аннотация:Study of the tree-ring growth along the northern timber-line at: Kola peninsula and in Finland in the Past demonstrated the existence of cyclic oscillations of the tree-ring width. The cycles obtained correlate with the fundamental periods of solar activity (about 90 and 23 years) and with the periods which are related to combinative frequences (about 18 and 33 years) of mentioned fundamental frequences. It means that the influence of the solar variability on the terrestrial environment and climate has a nonlinear nature.