Frozen Cracks as Specific Pathological Tissue of Oak Trees of Oak Recreation Zone of Voronezh City

Abstract

The article is devoted to the most specific to oak pathological signs in the plantations of the recreational zone of the city of Voronezh. These include frost cracks. Regularities of the manifestation of frost-breaking cracks and their significance are analyzed. On the basis of literature sources it is established that frost cracks appear on the trunk of oaks not only in extremely severe, but also in ordinary winters and affect the best, cleaned from the branches, part of the lower trunk, significantly reducing the yield of valuable assortments. The mechanism of crack formation on the trunks of living trees is given, with rapid and significant lowering of the ambient temperature. Occurrence of this feature in the oak forests of the forest-steppe is identified and analyzed. Evaluation of the role of frost crack in the weakening of oak trees is conducted. The causes and regularities of their appearance in various types of plantations are revealed. The data for all frost cracks are recorded with their differentiation into overgrown and unbroken cracks. Variation of this feature in various plantations is shown. Analysis of the structure of frost crack as a result of a disproportionate thermal contraction of the tissues of the outer and inner parts of the trunk is made. The location of the frost cracks is analyzed depending on the sides of the light and depending on the inclination of the trunk. Manifestations of the occurrence of frost cracks are analyzed depending on the combination of the inclination of the trunk and the sides of the light. Comparative characteristic of frost cracks on height of a trunk and extent on trees of other species is made. As a result, the occurrence of frost cracks in all ripening and ripe oak plantations of the recreational zone of Voronezh has been revealed. The ability of frosts to infect oak trees with stem decay and deteriorate the sanitary state of plantations is revealed. It is determined that frost cracks appear in the draft timber facing the north and east and have a well-defined specificity in place of location and extent.