Mechanical stability of Virginian juniper trees in steppe zone of the eastern-european plain

Abstract

The paper establishes a relationship between the temperature factor, a physico-mechanical parameter — the modulus of elasticity of the Virginian juniper (Juniperus virginianaL.) wood tissues and its crown architectonics. Thus, with high positive temperatures in summer, a decrease in the elastic modulus leads to slow bending of the skeletal branches, which, in turn, affects the crown projection area, as well as its light permeability and, as a result, the temperature and humidity under the canopy. First of all, the temperature will affect the mechanical stability of trees, which is characterised by a critical ratio of the trunk diameter to its length (coefficient d/l ≤ 0.009) and the lowest range of the trunk’s resilience. The article developed a scheme for the mechanical stability of the Virginian juniper — due to the appearance of gaps and, in general, changes in the architectonics of the crown, uneven heating of the trunk occurs, which leads to a disruption of its uniformity in terms of the physico-mechanical properties of tissues. Irreversible deformations and numerous trunk breakages were revealed at an average height of 1.5 ± 0.5 m and in the root collar zone. As a result, the light regime of the forest stand is disturbed, which affects the phytoclimatic and bioecological features of the forest steppe plantations. A change in the phytoclimate under the canopy towards increased illumination due to a change in architectonics leads to a decrease in stability and, as a result, the inability of woody plants to resist the pressure of aggressive herbaceous and tree-shrub vegetation.