Downward Migration of Coastal Conifers as a Response to Recent Land Emergence in Eastern Hudson Bay, Québec

Quaternary Research - Tập 40 - Trang 81-88 - 1993
Yves Bégin1, Dominique Bérubé1, Martin Grégoire1
1Centre d'études nordiques and Département de géographie, Université Laval, Québec, Canada G1K 7P4

Tóm tắt

AbstractPostglacial uplift in the eastern Hudson Bay area is among the most rapid in the world (300 m during the last 8000 yr). Although emergence curves based on 14 C-dated raised shorelines give a consistent basis for modeling relative sea-level changes, such a low-resolution dating method is inappropriate for estimating trends over recent decades. A major downward displacement of white spruce (Picea glauca (Moench) Voss) and tamarack (Larix laricina (DuRoi) K. Koch) occurred on protected shores as a response to shoreline retreat during this century. Analysis of the age distribution of trees indicates a progradation of white spruce and tamarack on gently sloping terrain ranging from 1.3 and 2.6 cm/yr, respectively, toward the sea. Improvement of climatic conditions during the 20th century favored such expansion which was probably faster than the real land emergence rates, but recent episodes of high water levels caused regression of forest margins over the highly exposed shores. Nevertheless, the downward trend of the treeline over this century substantiates the projections of 14C-dated coastal emergence curves during the modern period (1.0 to 1.3 cm/yr) by providing an estimate of the maximum rates of shoreline retreat.

Tài liệu tham khảo

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Quaternary Research

Tập 40

81-88

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