Factors affecting regeneration of Quercus robur in Bialowieza Primeval Forest

Abstract

Reasons for the apparent low density of Quercus robur recruits in Białowieża Primeval Forest are unclear. In this study we investigated the effects of facilitation by protective structures, negative effects of presence of mature Quercus robur and effects of forest type on the regeneration of oak saplings in the forest. Data was collected from 47 km of transects and on two scales: a large scale survey of forest characteristics using plots every 50 metres along the transects and a local scale survey of sapling characteristics and environment using plots centred on all of the 161 saplings found along the transects and nearby paired control plots. The study area consisted of a strictly protected area, and an area subject to limited management. Facilitation by protective structures, predominantly dead Picea abies debris, was shown to be particularly important for larger saplings due to their higher vulnerability to browsing. Presence of mature Quercus robur had no significant effect on sapling success. Saplings showed a strong tendency to be found in coniferous forest types as measured on the large scale but not necessarily to be found in proximity to coniferous individuals at the local scale. This forest type preference can be attributed to greater abundance of Picea abies debris as a source of protection in coniferous forest types; a weakened preference for these forest types was found in areas where tree debris was removed indicating that forest type preference is caused by high levels of tree debris in coniferous forest types.