Holocene pollen stratigraphy of Baird Inlet, east-central Ellesmere Island, arctic Canada |
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| Authors: | HANNU HYVÄRINEN |
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| Institution: | Department of Geology, Division of Geology and Palaeontology, University of Helsinki, Snellmaninkatu 5. 00170 Helsinki 17, Finland |
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| Abstract: | A 56 cm long core covering ca. 9,000 years was obtained from a small, unnamed lake (78°29.5'N, 4 76°46.8'W) at 295 m elevation, innermost Baird Inlet, Ellesmere Island. The vegetation is high arctic, but locally relatively rich, with areas of Cassiope tetragona–Empetrum–Vaccinium uliginosum heath on the steep slopes above the lake. Cores were taken from the basin centre through ca. 15 m of water. Basal sandy-silt is overlain by 51 cm of laminated silty-gyttja and fine detritus gyttja grading upwards to loose algal gyttja. Three radiocarbon dates indicate rates of sedimentation from 0.07 to 0.04 mm per year. Pollen concentration varies from 1,500 to 2,000 per cm3 in the lower part of the core to 100 to 200 in the upper part; calculated pollen influx is between less than one and 14 grains per cm2 per year. Four local pollen assemblage zones reflect an early pioneer phase (grass-sedge- Oxyria ) in the lowermost organic sediment, followed by the appearance and spread of Salix some 8,000 years ago and then, some 7,000 years ago, by a rise in Ericales. A period of vegetational stability with dwarf-shrub heaths follows, lasting for over 3,000 years. The topmost zone shows some increase in indicators of bare ground and fell-field vegetation ( Saxifraga, Ranunculus, Papaver , Caryophyllaceae, Dryas ) and decline in pollen influx, hence deterioration of local conditions during the last 3,500 to 4,000 years. |
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