VITALITY STRUCTURE AND ITS DYNAMICS IN THE PROCESS OF NATURAL REFORESTATION OF QUERCUS ROBUR L.

Abstract

The article focuses on the original approach to the division of woody plant populations into the intrapopulation structural groups – cohorts. It is shown that the distinctive features of the natural reforestation process are indicative of the six generalizing models. The essence of vitality analysis is revealed and the expediency of its application to the assessment of cohorts of forest-forming species is justified. The authors’ approaches to the study of the dynamics of vitality structure of cohorts by the stages of natural reforestation are proposed. It is shown that on the territory of Left- Bank Polissia of Ukraine the cohorts of Quercus robur differ significantly in the diversity of vitality structure. In most phytocoenoses the Quercus robur cohorts are characterized by the trend towards a decrease in values of the quality index that is often manifested during their transition to the next stage of natural reforestation. On the whole, the facts of steady gradual increase in values of the cohort quality index by the stages of natural reforestation have been registered in neither group of associations. In addition, the undergrowth of Quercus robur is often missing in forests, where this species is represented as part of the parent forest stand, and even where the generative cohorts of Quercus robur are characterized by high values of the quality index. This indicates a significant complexity of the process of self-renewal of oak forests in the conditions of Left-Bank Polissia of Ukraine and the actual lack of habitats, where there would be a complex of ecological and coenotic conditions optimal for the sustainable existence of Quercus robur as part of forest phytocoenoses. This may result in a decrease in the area of pure oak forests and forests with the participation of this species in the region under study and lead to the loss of a number of both sozological valuable forest communities and populations of rare species. These facts indicate the need to carry out the systematic monitoring of the state of oak forests and their natural reforestation in the region and, if required, to use balanced and science-based means to facilitate the natural reforestation of Quercus robur.