Relationships between morphological characteristics of roots and stem sapwood twisted layer of Scots pine trees growing in the upper bog

Abstract

The main objectives of the work are: to determine the presence and to assess the nature of relationship between the asymmetry of root system structure and the twisting of tree trunk; to study the nature of relationship between the morphological characteristics of the first order lateral roots, of the trunk and of the layer of sapwood for Scots pine (Pinus sylvestris L.) trees growing under the extreme hydrothermal conditions in the upper bog (Middle Urals, Russia). In two groups of trees (twisted and non-twisted) of the VI class of age (32 and 38 trees in each respectively), there were measured: trunk diameters without of bark at the root collar layer and at the distance of 1.3 m from it; the heights; the angles of inclination of wood fibers; the length of the twisted part of trunk and the height at which it begins; the number of lateral roots of the first order and the perimeters and the angles between them. In the analysis of the structure of root system there were used the indices of its asymmetry in terms of the location in space and of the radial growth. Values of indices were calculated for each tree as the average proportions of the difference between either the angles among individual roots or perimeters of roots from the average value. It was found that the variability of morphological characteristics of roots and the nature of their relationships differ in twisted and non-twisted trees. The evaluation of relationships between individual characteristics made it possible to identify 5 differences between two studied groups in the presence of statistically significant correlations (R = 0.34–0.52). The twisting of the trunk arises during the growth of tree and is not directly dependent from the structure of the root system. The appearance of the twisted layer is facilitated by a relatively small number of lateral roots and low spatial asymmetry of the root system. There are positive correlations between trunk twisted layer length and root growth characteristics, including maximum root thickness and asymmetry in root perimeters.

Keywords

• pinus sylvestris l.
• tree stem twisting
• twisted layer
• root system asymmetry