Extremely narrow and wide tree rings in the Norway spruce (Picea abies (L.) Karst.) of the Bia owie a National Park

Norway spruce trees grow in two main regions which meet in Poland, one to the north and east of Europe, the other to the south and west. Opinions about the distribution of Norway spruce have changed over the years, and its scarcity in the centre of Poland has been strongly debated. The currently favoured theory is that Norway spruce once had a continuous distribution in Poland. It is assumed that the rare occurrence in the central Polish lowland is due to a combination of unfavourable soil conditions and previous human activities. The main aim of this work was to analyse climate-growth relationships of Norway spruce from the boreal-Baltic range in Bia owie a National Park. Spruce growth is positively correlated with the rainfall from May to July. The longest chronology for the selected sites in north-eastern Poland in previous research, came from the Bia owie a National Park and covers the years of 1785-1999. The most typical negative pointer years are 1941, 1963/1964, 1979, 1992, 1999, whereas the positive pointer years are 1961 and 1981. Since forest management is minimised in the National Park such increment pattern could be a model for the spruce from the boreal-Baltic range in Poland.