Reconstruction of long-term successional dynamics of temperate woodland inBialowieza Forest, Poland

1 Bialowieza Forest contains the most extensive stands of old-growth temper ate woodland in Europe. It therefore has the potential to provide a model f or near-natural woodland, which is a conservation aim for many sites in wes tern Europe. 2 Pollen analyses from two small hollow sites in the northern part of Bialo wieza Forest National Park are reported here. The records cover the last 12 00-1500 years. The pollen data of the principal tree taxa were converted in to vegetation data using previously published pollen:vegetation correction factors. 3 These data were used to reconstruct long-term vegetation dynamics in the Tilio-Carpinetum and Pino-Quercetum communities that dominate the forest. C hanges in forest composition have occurred as a result of bo th autogenic a nd allogenic processes. High grazing intensities in recent centuries have b een particularly significant, although the forest is often considered to be undisturbed. 4 The larger hollow (site I) initially sampled across Peucedano-Pinetum, Ca rici elongatae-Alnetum and Tilio-Carpinetum communities. Since 1750, the Pe ucedano-Pinetum community has dominated, but with an increased Picea compon ent. This has recently been replaced by the Pino-Quercetum community follow ing the reduction of grazing pressure. These recent changes are largely con sistent with published successional models for Bialowieza Forest. 5 Site II recorded a relatively stable balance between the Tilio-Carpinetum and Pino-Quercetum communities until 750 years ago. The Tilio-Carpinetum c ommunity then expanded. The continued dominance of Quercus in this communit y is inconsistent with previous models. 6 The long time perspective available with pollen data permits the explorat ion of forest dynamics beyond the temporal range of existing models for Bia lowieza Forest. Comparison of recent and older records revealed that anthro pogenic impact on forest composition has been greatest in recent centuries. 7 This investigation highlights the significant role of history in determin ing forest stand structure and composition.