A late Quaternary vegetation history from Lily Lake, Chilkat Peninsula, southeast Alaska

Abstract

Pollen and plant macrofossil analyses of a radiocarbon-dated core from Lily Lake on the Chilkat Peninsula, southeast Alaska, provide evidence for the history of the Pacific Coastal Forest. A Pinus contorta woodland with an abundance of herbs and ferns initially became established after deglaciation (10 870 years BP). By 10 330 years BP, Alnus viridis had become a significant component of the pine woodland while herbs and other shrubs declined. At 9480 years BP, Picea sitchensis and Populus were locally present and P. contorta populations declined. Tsuga heterophylla, which dominates the modern vegetation, became locally established at 7880 years BP. The last major component, Tsuga mertensiana, joined the vegetation about 6710 years BP. The modern closed forest, dominated by T. heterophylla and P. sitchensis, became established about 2870 years BP. The arrival times for the dominant species are compatible with dates from other studies that suggest a northward migration along the coast. Key words: fossil pollen, Alaska, Quaternary, plant migration, coastal forest.