High-Resolution Record of Vegetation and Climate Change During the Holocene in Southwestern Québec

Abstract

A varved sediment sequence spanning the past ~11.0 ka was collected from Lac Noir (45.77N, 75.13W, 168 m a.s.l.) in southwestern Québec. A high-resolution pollen record documents the post-glacial vegetation history of the region over the course of the Holocene. The record shows an initial open spruce woodland, the establishment of the boreal and mixed conifer-hardwood forest into the area, as well as the expansion and contractions of tree populations in response to climate variability during the Holocene. The well known Tsuga decline at Lac Noir lasted 500 years starting at 5.5 ka and it took 1 460 years for hemlock to recover. The highest frequency of fire activity occurred during the early Holocene, and the lowest in the mid-Holocene. The late Holocene saw an increase in fire frequency, which could be attributed to a drier climate in eastern North America during this period. The impact of climate variability, fire disturbances and possible biotic factors on the Lac Noir vegetation are examined.