Paleoecology of postglacial tree line fluctuations on the Queen Charlotte Islands, Canada
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| Authors: | Pellatt, MG; Mathewes, RW |
| Year: | 1994 |
| Journal: | Ecoscience 1: 71-81 Article Link (DOI) |
| Title: | Paleoecology of postglacial tree line fluctuations on the Queen Charlotte Islands, Canada |
| Abstract: | Plant macrofossil and pollen analyses of sediments from a high elevation lake on the Queen Charlotte Islands, British Columbia, reveal changes in vegetation and inferred climate during the Holocene. Pollen and macrofossil zones at Louise Pond correlate well during the early Holocene, showing that vegetation changes recorded in the fossil diagrams occurred near the lake basins. Paleobotanical evidence for local presence of western hemlock (Tsuga heterophylla [Raf.] Sarg. trees between ca 9 600 and 8 700 +/- 150 yr BP indicates a warmer climate than today in the early Holocene. Declining western hemlock and increasing mountain hemlock (Tsuga mertensiana Bong.) fossils suggest some lowering of tree line at Louise Pond between about 8 700 +/- 150 and ca 7 300 yr BP. Radiocarbon dates from Shangri-La Bog and SC-1 Pond (7 190 +/- 100 yr BP and 7 180 +/- 110 yr BP respectively) show that climatic deterioration was occurring regionally by this time on the Queen Charlotte Islands. The development of upper subalpine mountain hemlock forest similar to today began around 3 400 yr BP and may correspond with climatic deterioration that caused the Tiedemann glacial advance (3 300 - 1 900 yr BP) in the south-coastal mountains of British Columbia. Plant macrofossil analysis in small lakes is shown to be useful in interpreting vegetation shifts in subalpine areas where lowland pollen rain interferes with interpretation of the local palynological record. |
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