Vegetation development after Neoglacial ice retreat and modern successional communities in pollen and spore spectra in College Fjord, south-central Alaska

Pollen and spore assemblages from a 2000-year sediment and peat sequence (core GLM-3) behind a Neoglacial recessional moraine provide a record of vegetation succession after ice retreat in College Fjord, south-central Alaska. The interpretation of the pollen sequence was aided by pollen assemblages collected in modern successional vegetation communities. Pollen data from the core show that between c. 2000 and 1500 BP, pioneer vegetation (dominated by <i>Alnus</i>) developed rapidly but stabilized between c. 1400 and 1300 BP, coincident with regional glacier advances. Major shifts in the composition of certain taxa occur between 1100- and 900 BP, especially with the incidence of Ericaceae and other taxa signaling disturbances. A period of <i>Tsuga mertensiana</i> dominance appears to show an advanced stage of forest development between 400 and 600 BP. From c. 200 to 150 BP, pollen data show the resurgence of <i>Alnus</i>, purportedly associated with the rapid retreat of glaciers. Thus, although pollen assemblages from modern successional communities are useful in the interpretation of long-term vegetation succession after deglaciation, this approach should consider that primary succession after the current glacier retreat is influenced by increasing anthropogenic disturbance and rapid global warming.