Palaeoecological studies based on the analysis of pollen in lake sediments offer the potential for high resolution and well-dated independent records of past vegetation and climate. Sulphur Lake, located in the southwest Yukon (60.95$\sp\circ$N, 137.95$\sp\circ$W; 847 m), was chosen for a paleoecological study to explore postglacial vegetation dynamics in this region of the boreal forest. A 5 m sediment core was raised from the deepest section of Sulphur Lake using a modified Livingstone piston corer. The sequence spans the full postglacial and reveals significant late glacial and Holocene vegetation changes that provide new information on the regional paleoecological history of the southwest Yukon. The pollen spectra indicate that between approximately 12,000 and 11,250 yr BP, the vegetation was an open alpine tundra marked by the presence of Artemisia. The vegetation then progressed from an open birch shrub tundra to a poplar woodland at 10,250 yr BP. Juniperus populations expanded at 9500 yr BP and by 8400 yr BP, spruce invaded the region. The relatively closed white spruce forest that occupies the region today was established by approximately 8000 yr BP. Alnus crispa increased at 6000 yr BP, however the increase in Picea mariana found at this time at most sites in the Yukon was not present at Sulphur Lake. Black spruce was not a dominant component of the vegetation in the Shakwak Trench as it was to the immediate southeast. The basal radiocarbon date demonstrates that the chronology of regional deglaciation needs to be more firmly established.
| Identifer | oai:union.ndltd.org:uottawa.ca/oai:ruor.uottawa.ca:10393/4395 |
| Date | January 1998 |
| Creators | Lacourse, Terri. |
| Contributors | Gajewski, K., |
| Publisher | University of Ottawa (Canada) |
| Source Sets | Université d’Ottawa |
| Detected Language | English |
| Type | Thesis |
| Format | 59 p. |
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