A continuous record of Holocene pollen from Harris Lake, southwestern Saskatchewan, Canada

Abstract

Holocene vegetation change in the West Block of the Cypress Hills, on the northern Great Plains, is interpreted from a continuous 9120-year pollen record. This is one of the few continuous pollen records available from the northern Great Plains which extends to the early Holocene. The West Block rises to a maximum elevation of 1465 m, and is a mosaic of grassland, Populus forest, coniferous forests, and wetland vegetation. Because of the ecotones present climatic changes produced vegetation changes discernible from the pollen record. The record indicates that a Populus forest-grassland complex was established by 9000 yr BP; very little coniferous forest was present at that time. The predominance of grassland and saline-tolerant vegetation between 7700 and 5000 yr B.P. defines the altithermal for this region. Climatic deterioration followed, as indicated by increases in relative amounts of conifer and aquatic taxa pollen. The Pinus contorta and Picea glauca forests characteristics of the Cypress Hills today only have been prevalent since about 4600 yr B.P.; both species were present in very low numbers throughout the altithermal. By 3230 yr B.P. the modern vegetation was established, with little change since then.