Vertical and horizontal structure of Scots pine (<i>Pinus sylvestris</i> L.) stands in the central part of the Russian Plain

The study analyses the vertical and horizontal structure of Pineta composita and Pineta hylocomiosa forest type groups in the centre of the Russian Plain. It was found that the structure in terms of heights and diameters of the first tier of stands is closer to the normal distribution in more ‘boreal’ sites. In more southern pine forests, large deviations from the normal distribution are observed. It was revealed that the closeness of the relationship between diameters and heights of Pinus sylvestris L. is in the range of 0.45 - 0.61. This is explained by the close heights of the preserved trees and the parcellar structure of the upper tier. It is shown that the structure of the second tier depends more on the age structure of the stands. It has been established that at present pine stands in the centre of the Russian Plain are characterised by processes of nemoralisation, which is also associated with climate transformation. As a result, in many cases there is a change of the main species, primarily by shade-tolerant species: Tilia cordata Mill. and Acer platanoides L. The revealed regularities can be used to combine with forest inventory data in order to obtain information on the formation of the lower tiers under the canopy of pine phytocenoses.