Biomorphological aspects of natural regeneration of Quercus robur L. on sandy sediments in the valley of the river Bolshoi Cheremshan (Ulyanovsk region)

Using modern biomorphological approaches, the crown structure of young Quercus robur L. specimens growing on sand outcrops with sparse herbaceous vegetation on the slope of the floodplain terrace of the Bolshoy Cheremshan River (Melekessky District, Ulyanovsk Region) was studied. A total of 106 trees were studied. The locus of immature specimens of normal and low vitality is located in the upper part of the slope near the forest edge. In other parts of the slope, immature plants are extremely rare and have low and low vitality. Virginile and young generative specimens grow along the entire slope and have mostly normal vitality. In the immature ontogenetic state, plants with an orthotropic trunk and rare ascending branches predominate. The crown structure in the virginile and young generative states is reduced to three types. 1 – orthotropic trunk and ascending branches, 2 – orthotropic trunk and predominantly plagiotropic branches, 3 – trunk transitioning from orthotropic to plagiotropic growth direction, plagiotropic and ascending branches. Type 1 individuals predominate. Most individuals of all ontogenetic stages have a complex of axes in the ground part of the trunk, including one or more of the following elements: either plagiotropic/ascending branches, or axes creeping along the surface of the substrate, or additional trunks inferior in development to the main one. Xylopodium was found in two immature individuals.