The paleoclimatic interpretation of exotic pollen peaks in holocene records from the eastern Canadian Arctic: A discussion

Processes involved in the transport of "exotic" tree pollen and its deposition in eastern Arctic Canada are reviewed. Synoptic meteorological situations favoring transport northward from the boreal forest are analyzed via boundary-layer trajectory computations. To account for reported exotic pollen peaks in Holocene peat deposits on Baffin Island, the necessary increase in frequency of southerly wind components may be as much as an order of magnitude, which could not be accomodated in the available time interval of pollen release, if sources from all of the Canadian boreal forest are considered. If only Labrador sources are involved, the absolute increase in southerly airflow may be unexceptional. It is also shown that changing airflow direction cannot be directly linked with longitudinal displacements of the 700 mbar trough at 75°W. Other possible factors that could have produced peaks in exotic pollen include variable sedimentation rates, variable pollen production, or a non-linear relationship between airflow frequency and pollen deposition.