Modern pollen and stomate deposition in lake surface sediments from acrossthe treeline on the Kola Peninsula, Russia

We sampled and analyzed surface sediments from 31 lakes along a latitudinal transect crossing the coniferous treeline on the Kola Peninsula, Russia. T he major vegetation zones along the transect were tundra, birch-forest tund ra, pine-forest tundra, and forest. The results indicate that the major veg etation types in our study area have distinct pollen spectra. Sum-of-square s cluster analysis and principal components analysis (PCA) groupings of pol len sites correspond to the major vegetation zones. PCA ordination of taxa indicates that the first axis separates taxa typical of the forest zone (Pi nus, Picea) from taxa typical of tundra and forest-tundra zones (Polypodiac eae, Ericaceae, and Betula). The current position of the coniferous treelin e, defined in our region by Pinus sylvestris, occurs roughly where Pinus po llen values reach 35% or greater. Arboreal pollen (AP)/non-arboreal pollen (NAP) ratios were calculated for each site and plotted against geographic d istance along the transect. AP/NAP ratios of 7 or greater an found within p ine-forest tundra and forest vegetation zones. Pinus stomates (dispersed st omatal guard cells) are absent from sites north of the coniferous treeline and all but two samples from the forested sites contain stomates. Stomate c oncentrations among the samples are highly variable and range from 10 to 45 8 per mi and positively correlate with the changing Pinus pollen values. (C ) 2001 Elsevier Science B.V. All rights reserved.