LONG-DISTANCE TRANSPORT OF AIRBORNE POLLEN IN SOUTHERN ONTARIO (CANADA)

An analysis of weekly air samples at four sites in southern Ontario (London, Toronto, Peterborough, Sudbury) provides conclusive evidence for the long-distance transport of pollen of the exotic taxa Entada (Mimosaceae), Dodonaea (Sapindaceae), and Ephedra (Ephedraceae), originating far to the south (at least 1000 km) of the recording stations. The nearest source area for the first two taxa is in the West Indies and Mexico, while Ephedra, previously noted in Late Quaternary sediments from the Great Lakes region, grows commonly in the southwestern region of the United States. Long-distance transport is corroborated by air-mass trajectory analysis and surface-wind patterns at time of exotic occurrences.