Tree-line dynamics in Ungava peninsula, northern Quebec

The characteristics of the present tree-line in continental Northern Quebec appear to be related to modern and past ecological conditions.14C dating of fossil trees and charcoal, and age structure of tree populations are used as evidence of tree-line dynamics over the last 400 yr. As inferred from t...

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Bibliographic Details
Published in:	Holarctic ecology Vol. 2; no. 4; pp. 239 - 248
Main Authors:	Payette, S, Gagnon, R
Format:	Journal Article
Language:	English
Published:	Munksgaard International Booksellers and Publishers 1979
Subjects:	Age structure Coniferous forests Ecoregions Forest ecology Forest regeneration Lakes Paleoclimatology Plant ecology Population ecology Trees Canada
Online Access:	Get full text
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Summary:	The characteristics of the present tree-line in continental Northern Quebec appear to be related to modern and past ecological conditions.14C dating of fossil trees and charcoal, and age structure of tree populations are used as evidence of tree-line dynamics over the last 400 yr. As inferred from the reproductive strategies of the two tree species, black spruce Picea mariana (Mill.) BSP. and Tamarack Larix laricina (DuRoi) K. Koch, forming the present tree-line populations, major changes during postglacial time in Northern Quebec are not only concerned with tree-line position, but also with tree-line composition. The present tree-line is made by larch (or tamarack) and corresponds to its natural seed regeneration limit. Black spruce probably reached its northernmost holocene latitudes during a warmer period and it then formed the tree-line. During the Little Ice Age, fires destroyed large tracks of forest and black spruce krummholz (400, and 250-200 yr ago); afterwards, tree species reestablished only in protected sites, and exposed sites were not reseeded. At some places, fires did not burn completely the forest cover, and preserved isolated trees and small groves probably became locus of reafforestation. Differential forest regeneration and tree age structure suggest that fire and climate are intimately associated in controlling tree population dynamics. Favourable and less favourable forest regeneration periods are inferred from these data and it is suggested that tree-line displacements in Northern Quebec during the last 400 yr were less important than in the Northwest Territories.
ISSN:	0105-9327