GROWTH AND DEVELOPMENT OF THE CEDAR (PINUS SIBIRICA DU TOUR) ADOLESCENT UNDER THE FOREST PROTECTION AND ON THE CUT-OVER AREAS OF SOUTH-WESTERN YAKUTIA
The patterns of growth and development of Siberian cedar undergrowth (Pinus sibirica Du Tour) on the northeastern boundary of the range (southwestern part of Yakutia) are relevant due to their poor knowledge. The aim of the work is to study the renewal of cedar undergrowth (Pinus sibirica Du Tour) in the South-Western Yakutia forests. Field geobotanical and route methods were used in field study of the flora of the studied forests. Trial plots of various sizes were laid in different parts of the forest to account the renewal. Correlation analysis of the growth rate of cedar undergrowth with climatic conditions was taken for 15 years in forest types represented by different conditions of growth and the composition of tree species and vegetation under the canopy of the stands. The greatest number of undergrowth of cedar was noted under the canopy of stands, where the participation of mature cedar trees is from 3 units or more. These types of forests are characterized by a low crown density, the undergrowth is usually absent. There is a significant dependence of the growth of cedar regrowth with the amount of precipitation in May, and the relation between the growth of cedar regrowth and air temperature in the spring and summer months. The amount of precipitation in the winter in an open area is very much significant. This season is associated with very low negative temperatures and the presence of heavy snow cover. Snow cover favorably affects the safety and protection of the root system of the undergrowth. The accumulated snow on the crowns of adult trees can cause the snowbreak of young branches of the undergrowth, as indicated by the negative correlation dependence of the increment value with precipitation in the winter months. However, in general the relationship between the growth of cedar regrowth and rainfall under the forest canopy is insignificant.