Structure and dynamics of temperate lowland natural forest in the Białowiez ∙ a National Park, Poland

Summary The world-renowned Bialowiez · a National Park (BNP) in Poland has long been the object of research that provides information on the status and development of the entire, relatively large area of well-preserved lowland forest. For that reason, the aim of the work presented here was to characterize the current structure and dynamics of natural forests in Strict Reserve of BNP (SR-BNP), which covers 4584 ha. The research material encompassed the results of measurements on 460 temporary and 160 permanent sample plots. Results revealed an increase in the level of regeneration, whereas the standing volume is seen to have decreased slightly. Changes occurred in volume of certain tree species, as well as in proportions in given size classes they accounted for. The most marked increase was noted for Carpinus betulus, followed by Alnus glutinosa, Tilia cordata, Betula spp., Acer platanoides and Pinus sylvestris. Only in the case of Picea abies was a significant decrease noted. A decline of P. abies, mainly due to Ips typographus infestation, was revealed. Currently, only 6 of the 17 species of trees growing in the SR-BNP included specimens that were growing from the regeneration layer into the overstorey in more significant numbers. Due to a reduction of species diversity in ingrowth, a gradual depletion of species richness in the SR-BNP stands should be anticipated.