Past and present Scots pine (Pinus sylvestris L.) regenaration along site type gradients in Bialowieza Forest, Poland
Abstract: Since 1921 the Białowieża National Park (BNP)/Poland strictly protects one of the bestpreserved ancient lowland forests of the European temperate zone, with many stands close tonatural character. Within the reserve, old Pinus sylvestris trees grow on fertile soils in a mixeddeciduous forest (oak-lime-hornbeam forest Tilio-Carpinetum) with a very rich and densefield layer. This study will explore the features of P. sylvestris trees and if this earlysuccessionalspecies is able to regenerate and establish under such habitat conditions aspresent today. On three such Tilio-Carpinetum typicum study areas (in total 230 ha) 723 P.sylvestris trees were inventoried and mapped during transect walks over site type gradients.Mean tree density for all sites was low with 3,1/ha. 70% of alive trees had a DBH of 46-89cm (μ= 64,5) and 50% of alive trees were ≥30 m in height. 85% of all trees were estimated tobe ≥100-250 years old, none alive tree younger than 50 years. Fire scarred were 18,4% of allScots pines recorded, half of those additionally modified by chipping for wood splints, beehivecaves or axe cutting by people (CMTs). These marks are undoubtedly signs of pastanthropogenic utilization impact on appearance and history of the studied forest stands. Atleast 52 pine trees were multiple fire-scarred, with a range of 2-10 fire events counted.Maximum height for open fire scars was 320 cm. There was no single P. sylvestris seedling orsapling found during the regeneration inventories in June 2010. Not even where better lightconditions or soil disturbances with a reduced field layer coverage occurred. Due tosimilarities to Scots pine in its ecology Pedunculate oak (Quercus robur L.) was included inthe macro-scale regeneration inventory: seedling/sapling density ranged between sites from 1to 89,1 oak individuals/ha. In the micro-scale regeneration inventory, Acer platanoides,followed by Tilia cordata, Fraxinus excelsior and Carpinus betulus seedlings was the treespecies with the highest frequency. In the sapling stage instead, the dominant abundance ofNorway maple was followed by hornbeam and Ulmus spp. In sum 28 dead Scots pines werecored for age determination: the oldest tree on the study sites germinated in 1637, 1642 and1728 respectively. Overall about 15 irrregular regeneration pulses could be detected from thesamples for the time period 1637-1852. A share of 33% of all estimated germination datesfalls within a 15-year interval, stretching from 1767 to 1782. Longer fire-free periods, e.g.after a likely fire in 1777, allowed Scots pine to recruit and to be resistant enough to survivefollowing fires, as those dated from scars during the 19th century, namely in 1822, 1833, 1851and 1861. Fire could serve as one hypothetic explanation (besides eutrophication) for theappearance of P. sylvestris in richer habitats in BNP, formerly promoted by people in theregion due to traditional forest utilization. The diminishing influence of man in BNP maycause the depression in regeneration of short lived pioneers and climax, light demanding treespecies like Pedunculate oak and Scots pine.
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