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Recent paludification of kettle holes on the central isjands of Lake Bienville, northern Quebec, Canada
Centre d'etudes nordiques and Departement de geographie, Universite Laval, Quebec, Canada GIK 7P4 This paper reports on the paludification of kettle holes formed in a proglacial esker complex at Lake Bienville in northern Quebec. Deep hollows on the central islands of this large subarctic lake (c. 900 kin2), are highly exposed to northeasterly and southwesterly winds over long fetches, and accumulate large amounts of drifting snow (c. 4 m). Modifications in local snow distribution associated with Holocene vegetation and climate changes contributed to an increased water supply in kettle holes. Podzolic soils with light patches in the B horizon are attributed to differential water circulation during thawing in coarse-textured soils with high moisture supply associated with thicker snow. Peat started to form over well-drained podzolic soils after 600 BP, especially c. 200 BP, when suitable conditions for Sphagnum growth established at the front of snowbeds. The recent development of patchy podzolic soils and paludification of kettle holes are interpreted as the result of a combination of bioclimatic events including: (l) the development of a postfire, open-vegetation cover after c. 1500 BP associated with cooler conditions exacerbated by the presence of a large water body; and (2) the shift from a boreal-to a subarctic-like (wind-controlled) snow regime permitting the accumulation of large amounts of snow and late melting.
Key Words: Kettle holes • fire chronology • snow regime • Sphagnum capillifolium • paludification • soil development • climatic change • forest tundra ecotone • subarctic • Quebec • Canada
The Holocene, Vol. 8, No. 1,
91-96 (1998) |
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