Postglacial vegetation community change over an elevational gradient on the western Kenai Peninsula, Alaska: pollen records from Sunken Island and Choquette Lakes

• Published in: Journal of Quaternary Science
• Main Authors: Scott Anderson, R., Berg, Edward, Williams, Chris, Clark, Tami
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2019
• Subjects: Dwarf birch; Tundra; Alaska
• Online Access: http://dx.doi.org/10.1002/jqs.3102; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fjqs.3102; https://onlinelibrary.wiley.com/doi/pdf/10.1002/jqs.3102; https://onlinelibrary.wiley.com/doi/full-xml/10.1002/jqs.3102

Abstract The Kenai Peninsula of south‐central Alaska is a region of high topographic diversity with a complex glacial history. The sedimentary record of two small lakes [Sunken Island (SIL; 76 m a.s.l.) in the Kenai Lowlands; Choquette (CL; 527 m a.s.l.) in the Caribou Hills upland] exemplifies the postglacial development of the conifer–hardwood forest over an elevational range there. A herb–shrub tundra was established at both sites after deglaciation. By ~10.7 ka, poplar ( Populus sp.) and alder ( Alnus ) dominated the lowland forest, while alder with minor poplar occurred at the upland site. Lake levels lower than today occurred during the early Holocene until ~8 ka. Subsequently at SIL, the near‐modern Kenai birch ( Betula kenaica ) – white spruce ( Picea glauca ) forest maintained prominence throughout the Holocene. However, at CL, alder dominated with dwarf birch and other subshrubs; small amounts of white spruce arrived ~5.2 ka. Black spruce ( Picea mariana ) grew around SIL by ~4 ka, but never gained prominence at CL. Fire, a prominent agent of disturbance in the Kenai Lowlands since ~8 ka, was essentially absent at the hardwood‐dominated upland site before ~6 ka, and rare thereafter. This suggests an important link between fire and spruce in Kenai forests.