Vegetation patterns, pollen dispersal and pollen deposition in pollen traps and arctic lake sediments in West Greenland

Vegetation patterns, pollen dispersal and pollen deposition in pollen traps and arctic lake sediments in West Greenland

Lenssen, T.

Molengraaff Fonds

2002-06

In order to interpret palynological records from the late-Quaternary and Holocene correct, a good understanding of pollen production and dispersal efficiency in tundra vegetation is necessary. Yet, only few studies in the arctic have dealt explicitly with the question of pollen transfer processes to lake sediments and aspects of representativity. In an enclosed lake system near Kangerlussuaq (West Greenland), catchment vegetation patterns have been compared with modern pollen rain (pollen traps distributed throughout the catchment) and lake surface sediments. Differences between pollen traps in the catchment are caused by species with low pollen dispersal, like Ericaceae. Presence or absence of extra local or regional species in the vegetation cover, hardly have any effect on pollen percentages i n the traps. However, trap design and wind turbulence in the catchment can lead to spurious results. Compared to the vegetation cover, Betula nana is over- and Ericaceae are under-represented in the lake sediment. Salix and Gramineae are quite well represented in the lake sediment. Betula pubescens is highly overrepresented i n the lake sediment compared to the traps. Probably due to size difference between lake and trap. Lake sediment samples reflect more or less the regional vegetation. It can be used for reconstructing the catchments vegetation, but only when taking differences i n representation in account.

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Utrecht University

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(c) Tim Lenssen