Intensification and specialisation of agriculture and forest use has led to profound structural and compositional changes in European landscapes. In particular, sharp, narrow edges adjacent to relatively homogenous vegetation types progressively replace transitional habitats, crucial for a plethora of species and ecological processes. Quercus robur and Q. petraea regeneration niches make them best adapted to such transitional habitats. However, contemporary oaks’ importance, including their regeneration, is usually considered within limits of forest habitats.

The oak (Quercus robur L.) regeneration intensity was assessed in the core area of the Białowieża National Park (BNP) in Poland with respect to the selected ecological factors. The emphasis was placed on the response of oak regeneration to disturbances, including the large-scale dieback of spruce stands. Defining their effect could help predicting the role of oak in naturally developing lowland forest ecosystems in the European hemiboreal zone. The results of the study challenge the opinion that the ‘lime-oak-hornbeam forest’ is a ‘climax’ community, confirming a very poor regeneration represented by only two saplings taller than 0.5 m per hectare. By contrast, in spruce-dominated communities, from 49 to 848 taller saplings per hectare were found. The occurrence of saplings was associated with discontinuous canopy of late seral stage of stands, as well as with large gaps. Most of the best quality grown-up oak saplings developed in the immediate neighbourhood of spruce logs. The results of the research indicate that ‘lime-oak-hornbeam forest’ (Tilio-Carpinetum) should be rather perceived as a transient community, evolved from relict, culturally modified, oak woodlands. Because spruce had become a dominating species only after abandoning in mid-1800s the historical regime of anthropogenic disturbances (involving frequent forest fires), the observed phenomena related to the disintegration of spruce stands had probably no precedent over the last 500 years. To confirm whether the massive decline of spruce stands will finally result in the successful establishment of the new canopy oak generation, both in Białowieża and other forests of hemiboreal zone, further research is needed.

The present and past population status of oak (Quercus robur) in the Białowieża National Park preserve (BNP) was analyzed with respect to the historic use of the ecosystem. I assessed average parameters (density, dbh distribution, differences between habitat categories) of the oak population in the whole BNP preserve, and performed detailed analyses of local populations on three 26.5-ha and one 3.5-ha plots, representing eutrophic sites of deciduous forest (3) and a mesotrophic site of mixed forest (1). Based on the tree ring data, I reconstructed the historic dbh distribution back to 1750–1825. The results of the reconstruction confirm the early 1800s expert account and the 1889 forestry survey report. The high oak concentration in eutrophic habitats are legacies of either active game management (e.g., bison habitat improvement measures, supplementary feeding), forest recovery after the ban on forest industries (baking potash, tar, charcoal), or abandonment of inner small farms. The emergence of oak on poorer sites in the mid 1800s coincides with the ban on use of fire—a common practice that earlier had perpetuated the dominating position of fire-resistant pine. The present oak regeneration in declining spruce stands is a further step of the forest natural adaptation to environmental changes. The study supports the view that BNP is a remnant of an ecosystem substantially shaped by human uses. Modern forestry, as practiced in the managed part of the Białowieża forest, does not mimic either natural processes (as observed in BNP) or historic forest uses.