ВІТРОВАЛЬНІ ФОРМИ РЕЛЬЄФУ, ПОШИРЕНІ В МЕЖАХ ТЕРИТОРІЇ УКРАЇНИ

Abstract

There are rather ubiquitous relief forms on the Ukrainian territory, which are created by strong winds within the forest lands and other areas where woody vegetation is represented. This article analyzes peculiarities of the emergence of such windthrow relief forms as windthrow hills, hollows, microstrands, microcaves, percussive microcraters and root blocks. By size, they predominantly have a rank of nano- and microrelief while their surface is often complicated by picoforms of relief. According to the materials of our own field research in different regions of Ukraine and based on the analysis of available publications on the subject, morphological and morphometric features as well as the density of the location of such relief forms within the territories with domination of woody vegetation were described. On the grounds of the field research, it can be concluded that hollows, hills (“earth hills’) and microstrands are the most widespread windthrow relief forms. The mechanism of their formation can be described in the following way: the root system of the tree breaks out under the influence of the wind, captures a certain amount of soil and forms a windthrow hollow on the place where the tree used to grow, a windthrow hill (“earth hill’) appears on the edge of the windthrow hollow from which the windthrow microstrand branches out. The dimensions of the windthrow hills and hollows depend mainly on the structure and condition of the root system and the composition of the soil. Meanwhile, the dimensions of microstrands depend on the length and diameter of the tree trunk and the height of the windthrow hill. As a result of falling of mature trees up to 1m deep hollows are often formed. Only occasionally, they have a rounded shape with a diameter of about 2m. In most cases, these relief forms are oval, 2-3 m in length and 1-2 m in width. Smaller windthrow forms occur when relatively small trees fall. The density of the windthrow hills, hollows and microstrands in the forest lands of different regions of Ukraine can range from several items to several dozen per 1 hectare. In some cases, during strong winds, windthrow “microcaves” (the result of incomplete root canal deformation) and percussive “microcraters” (the result of hitting the earth’s surface by broken trunks and large branches) are formed. On the slopes, as a result of the interaction of eolian activity, gravity, phytogenic factor and sometimes erosion, the formation of such a kind of windthrows as “root blocks” might take place. The study of such relief forms enables to assess the role and extent of the influence of the eolian factor and biota on the formation of morphosculptural characteristics of the surface of particular regions of Ukraine.