Dendrochronological studies were conducted in polar forests of Ary-Mas forest (Taimyr Peninsula). We have identified two waves of mass regeneration of Dahurian larch in the mid-1950s and the first half of the 1980s. In the dynamics of tree ring greatest imprint left the first period. Until the mid-1950s highest growth stands were characterized by woodlands and from the second half of the 1950s before present maximum increase is observed in the forests. The most likely reason for this was the increase in capacity of the snow cover in the forests. Over the past 50–60 years has been stable thermal regime but there was a significant increase of precipitation especially in the winter mostly in forests. Later destruction of snow cover and a thermal insulating effect of moss cover in these habitats have led to decreased production of larch forests.