A 12 000 year record of vegetation change and soil development from Wien Lake, central Alaska

Pollen, plant-macrofossil, macroscopic-charcoal, and geochemical analyses of a sediment core from Wien Lake provide new information on the late Quaternary environmental history of central Alaska. Shrub tundra dominated by Betula glandulosa occupied the area 12 000-10 500 BP. Low plant cover and intensive soil erosion of the tundra landscape are indicated by low pollen-accumulation rates, high sediment inorganic content, and high allogenic elemental concentrations. Around 10 500 BP, Populus and Salix invaded the shrub tundra and open ground to form dense stands within the lake catchment. The marked increases in sediment organic content and authigenic concentrations of Fe, Mn, and Al during the period of Populus-Salix dominance suggest humic buildup and stabilization of the catchment soils. These soil changes in turn may have contributed to the demise of Populus-Salix communities 9500 BP. After 6500 BP, modern boreal forest dynamics are indicated by the dominance of Picea mariana, fluctuations of Picea glauca, and frequent occurrence of local fires. -from Authors