Pollen productivity estimates from old-growth forest strongly differ from those obtained in cultural landscapes: Evidence from the Białowieża National Park, Poland

Abstract

Pollen productivity estimates of individual plant taxa are necessary when determining changes of vegetation cover during the Holocene. To date, studies describing this parameter in lowland temperate Europe have been carried out in cultural landscapes showing low forest cover and dominated by human activities. However, these may be of limited use when applied to reconstruct past land cover, for instance, from pre-agricultural landscapes. The aim of this paper is to ascertain whether pollen productivity from the closed-canopy old-growth forest in the Białowieża National Park, Poland, where human impact has been minimal for nearly a century, is different from that calculated in much more open landscapes. We ask: how much does forest antiquity and structure influence the amount of pollen released from particular taxa? We implemented maximum likelihood estimation of relative pollen productivity for seven tree species and for Poaceae using 18 modern pollen assemblages and distance-weighted plant abundances. Our results demonstrate that the ratio of pollen productivity between high producers ( Pinus sylvestris and Quercus robur) and low producers ( Poaceae, Corylus avellana) is on an average six times greater in Białowieża than across other European cultural landscapes. Pollen from forest Poaceae and C. avellana is six times more under-represented in old-growth forest than hitherto estimated from cultural landscapes. This finding reinforces the idea that pollen productivity can vary in response to changes in the prevailing environmental settings and we present for the first time a quantification of this variability, likely induced by differences in light availability.