Crown architecture of Quercus robur L. in the reproductive period of ontogenesis in phytocoenoses of the northern forest-steppe in the Tula Region

The diversity of the habitus in reproductive individuals of Quercus robur L. in phytocoenoses of the northern forest-steppe within the Kulikovo Pole museum-reserve in the Tula Region was analysed. The individuals grow-ing in the ravine and upland closed and open forests as well as open-growth individuals and groups of individu-als in the forest outliers were researched. One-trunk, a few-trunk, coppice and clump life forms were detected. It was shown that the types of the habitus or architectural types (AT) in reproductive individuals resulted from those AT that were firstly described in the virginal ontogenetic state and in the beginning of the young reproduc-tive state in the mixed forest and broadleaved forest biomes. The quantitative and qualitative changes of the shoot systems were found out. The ways of the crown transformation are ten in number. They include acropetal mortality of the branches from the trunk, basipetal mortality of the shoot systems, decrease of the trunk branch-ing frequency, secondary crown formation, trunk deviation from the orthotropic growth direction, increase of the polyarchic plan of organization in trunk, trend of branch drooping, disarrangement in crown zoning, increase of the polyarchic plan of organization in branches, immediate reiteration. The most survived initial crown architec-ture is expressed in the open-growth individuals that grow on the slow slopes. The most common way of trans-formation is acropetal mortality of the branches from the trunk. Its intensity depends on the closeness of the stand. Besides light level, crown architecture in the reproductive period of ontogenesis is influenced by the indi-vidual’s position in relief, which affects the aerologic and hydrologic regimes of the phytocoenosis.