Ontogenetic tactics of morphological characteristics of the Betula pendula Roth leaf in the gradient of technogenic soil transformation under changing weather conditions

The variety of types of otnogenetic tactics is shown on the example of the structural features of the leaf of Betula pendula Roth growing under conditions of technogenic soil transformation in the Tagil zone of the Middle Urals (Sverdlovsk oblast). It has been established that the leaf structure of this species contains features that are characterized by various types of ontogenetic tactics, both pure and combined. The most represented are convergent-divergent and convergent tactics. The signs that are characterized by different types of tactics in the lower, middle and upper parts of the leaf are revealed. Conducting research during the growing seasons (2016–2019) with different degrees of favorable weather made it possible to establish that the type of ontogenetic tactics characteristic of individual leaf traits on the technogenic stress gradient can change depending on weather conditions. Such characters include the length of the lateral vein, the angle between the main and lateral veins of the first order, the distance from the tip to the widest part of the leaf, the length of the leaf blade and petiole, the leaf blade index and the leaf index. Along with this, signs were revealed that, in the gradient of technogenic transformation of soils, regardless of the degree of favorable weather, retain the type of tactics: the distance between the ends and bases of the lateral veins, the width of the leaf blade and the width of half of the leaf blade, the distance from the widest part of the leaf to the base.