Eight years of annual pollen monitoring in northern Sweden, from the boreal forest to above the birch forest-line

Abstract

Pollen deposition during 1997–2004 was monitored for seven sites in northern Sweden, ranging from the boreal forest zone to above the birch forest-line. Fifty-three taxa were recorded in the traps. Of these, 22 are observed in the vegetation surrounding the trap sites. The remaining 31 taxa are most probably long distance transported. Taxa that strongly correlate with the site above the birch forest-line are Trientalis europaea, Asteraceae, Ericales and Linnaea borealis, while pollen of Pinus, Picea, Betula, Alnus and Juniperus correlates with sites within the boreal forest zone. A positive correlation is noted between pollen accumulation rates (PARs) of Pinus and Picea and mean July temperatures of the year prior to pollen release. A comparison between pollen counts retrieved from pollen traps, lake surface sediments and moss polster samples at one site shows similar pollen composition for the pollen trap and lake surface sediments, while the moss polster samples have higher percentage of Pinus pollen, lower percentage of Betula pollen and generally a lower diversity of pollen and spores.