Vegetation and lake-level history at Birch Lake, interior Alaska

In interior Alaska (mean ann. precip. ca 350 mm) lakes should be sensitive to changes in the P/E ratio. At Birch Lake, near Fairbanks, lake levels rose dramatically 11,000-9200 years ago, fell 9200-8500 years ago and then rose rapidly, probably in a few hundred years. Some major changes in vegetation appear coincident with the lake-level changes, but others do not, or are hard to interprete. Populus woodland expanded during the first transgression, but subsequently declined while lake levels were still high. 9000-8000 years ago Picea glauca expanded then decreased, its abundance apparently negatively correlated with moisture availability. The lake rise at ca 8000 yr B.P. is slightly preceded by regional expansion of Alnus. Data suggest that a complex interaction of climatic and non-climatic factors determined vegetation dynamics during the late-Quaternary in interior Alaska.