EN
The aim of the paper is to define a relationship between the diversity in structural features of the Carex digitata population and the dynamics of natural and disturbed anthropogenically oak-hornbeam communities in the cycle of 29-year research (1987-2015) conducted on permanent plots in the Knyszyńska Forest. The results of the research indicate that the population dynamics corresponds significantly to the community dynamics, whereas the existing interrelations are a response of Carex digitata population to dynamic vegetation changes undergoing in natural habitats (fluctuation) and under the influence of anthropogenic disturbances (degeneration as a result of pinetization followed by regeneration). This is reflected in a different spatial organization, age structure, size diversity of individual plants, as well as in various mechanisms regulating the number of individual plants in a population. Models of population dynamics in the light of dynamics of the natural and disturbed forest communities can be explained from the viewpoint of equilibrium and non-equilibrium in the nature. It has been proved that in stable communities, where variations in vegetation have a character of little fluctuations and indicate a state of a relevant equilibrium in the nature, the population of Carex digitata also reaches a phase of relevant equilibrium. In such a phase the size of the sedge population is small and changes in the number of individuals in the 29-year cycle slightly fluctuate. A different variation in the population features has been reported in the anthropogenically disturbed community. Processes of degeneration and regeneration are accompanied by rapid dynamic vegetation changes (a state of non-equilibrium) and rapid changes in structural features of the Carex digitata population. The sedge reaction to the dynamic variations in the communities can be explained by a different life strategy which differentiates morphological and developmental features of individuals and thus determines variation of properties of the population.