Holocene vegetation and climatic change in the Peace River district, Canada

Abstract

A sediment core from a pond on the Alberta Plateau in the Peace River district of British Columbia was studied using pollen analysis and radiocarbon dating. Percentage and influx diagrams were produced, and radiocarbon dates were corrected to calendar years to calculate the sedimentation rate. The 231 cm core terminated in clay, and a basal date of 7250 ± 120 years BP was obtained, several thousand years after the recession of Glacial Lake Peace. The formation of the pond is interpreted as resulting from a climatic change, probably a transition from the peak of the Hypsithermal. Zone 1, from 7250 to 5500 years BP, is interpreted as representing a seasonal slough, with upland vegetation percentages consistent with a boreal forest. At about 5500 years BP a permanent pond with surrounding sedge wetlands was formed. Vegetation has been essentially modern during the last 3100 years. Measurements of spruce grains suggest the presence of black and white spruce throughout the pollen record. The formation of permanent ponds and wetlands on the Alberta Plateau at about 5500 years BP is thought to have been the most important vegetation change of the last 7000 years, which may have affected faunal and human populations.