An investigation of the Holocene pollen record from the Grey Islands, Newfoundland

Evans, Nicola S. (2002) An investigation of the Holocene pollen record from the Grey Islands, Newfoundland. Masters thesis, Memorial University of Newfoundland.

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Abstract

An 800 cm core from a lake (104 m; 50°46.08'N, 55°31'W) on the Grey Islands, situated in the Labrador Sea 20 km east of Newfoundland's Northern Peninsula, provides a nearly complete Holocene pollen sequence with a distinct maritime influence. By 9800 BP (705 cm), the site had emerged from the postglacial Daly Sea and a herb-shrub tundra was established. Tundra persisted until 7800 BP when spruce and fir invaded to form boreal forest. Fire at 7300 BP resulted in a brief resurgence of herbs and shrubs, primarily alder, followed by forest re-establishment by 6800 BP. Paludification led to an increase in Sphagnum and greatly decreased pollen influx after 3000 BP, followed by an increase in shrubs and herbs at the expense of trees after 1000 BP. Today the Grey Islands are dominated by tuckamore (dwarf shrub barrens) with patchy areas of black spruce forest and sphagnum bog. -- Timing of initial forest development at the expense of shrub tundra (7800 BP) coincides with other sites on the Northern Peninsula, though as much as 1 ka later than the rest of the island and slightly earlier than in southeastern Labrador. Increasing tree birch between 7000 and 4500 BP is indicative of higher summer temperatures and a longer growing season, while also signalling the weakening of a cold ocean influence which, in pollen and dinoflagellate cyst records from the Labrador sea, is dated about 7000 BP. A major forest fire in the record falls within the 8000 to 6500 BP period of increased fire frequency on the Northern Peninsula. Water temperature in the Labrador Sea reached a maximum around 6000 BP, coincident with the start of the hypsithermal period on the Grey Islands. After 2500 BP the Labrador Sea re-exerted a cold bottom water influence and the Grey Islands experienced paludification and forest demise.

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