On the Prostrate Growth Form of the Pedunculate Oak

Studying the plasticity of tree life forms helps to understand the mechanisms ensuring the stability of their populations in forest communities. The object of the study is the prostrate life form (trailing shrub, ‘stlanec’) of the pedunculate oak (Quercus robur L.). The aim of the work is to show the importance of prostrate form for the stable existence of oak populations in forest coenoses. The oak was studied in Nerussa-Desna Woodland. Field studies have revealed that the prostrate form of oak forms under limited illumination in bilberry pine forests, cowberry pine forests, green moss — cowberry pine forests, mixedherb pine forests and cowberry-bilberry birch forests. Morphological analysis has shown that the prostrate form forms in several ways: lying down and rooting of the orthotropic trunk, of lower horizontal branches and shoots of the undergrowth, as well as of forming shoots of quasi-senile individuals. The prostrate life form is a manifestation of the oak’s phytocoenotic tolerance. The prostrate form is a variant of the undergrowth characterised by extremely low vitality. In this depressed state, the oak can exist under the forest canopy for more than fifty years. With improved illumination, the prostrate form first transforms into a semi-prostrate form, and then into an upright crown-forming tree. This demonstrates the optionality of the oak’s prostrate lifeform.