Ragweeds, Ambrosia Species, in Canada and Their History in Postglacial Time

Abstract

Specific differences of Ambrosia artemisiifolia, A. trifida, and A. coronopifolia are described and their present Canadian distributions are reported in detail. Ambrosia pollens, identified in fossil assemblages as either A. artemisiifolia or A. trifida with a few in the size range of A. coronopifolia, were somewhat more abundant in late-glacial deposits than in younger postglacial sediments except the subrecent ones. It is only within the last 200 years that ragweeds have again become abundant in eastern Canada. The migration and spread of the three ragweed species in eastern and western Canada through postglacial time are discussed. There is evidence through pollen profiles that Ambrosia species existed further northward in Ontario than they do at the present time. In studying the presence and abundance of Ambrosia pollen in surface samples, the authors showed that ragweed pollen can be transported through the atmosphere at least 375 miles from any known source.

Contemporary pollen spectra in the James Bay Lowland, Canada, and comparison with other forest-tundra assemblages

“…Its presence reflects the good dispersal properties of Ambrosieae pollen. BASSETT and TERASMAE (1962) reported a ragweed pollen value of 3% from a surface sample site near Moosonee, similar to the regional abundance obtained here. The presence of Sarcobatus is interpreted to be a result of long distance wind transport as this genus is native to the American west and southwest (MAHER, 1964).…”

Two statistical approaches to forecasting the start and duration of the pollen season of Ambrosia in the area of Lyon (France)

“…The introduction of two North American species, A. artemisiifolia L. and A. trifida L., occurred in Lyon in 1930 and then again during the Second World War, probably as contaminants in cereal sacks (Touraine 1984), even if some rare occurrences were found as early as 1875 in some French regions such as the Loire valley or the Rhône valley (Coste 1937). Ambrosia distribution can be related to climate; in Canada it grows in cold temperate latitudes, particularly in south-eastern Saskatchewan, southern Manitoba, southern Ontario and Quebec; while it is very rare in British Columbia and Alberta (Basset and Terasmae 1962), the Laurentides being the northernmost region where it is found, in the Montreal region the plant is endemic (Banken and Comtois 1992). In the United States, it grows in the climates of the eastern side of the continent at medium latitude, the climate of the subtropical part of Florida and Texas, and it seems to avoid all the Pacific coast, the plant being rare in the western states where the altitude is highest and also in the southernmost tip of Florida and northern Maine (Anonymous 1987).…”

Climate changes, lead pollution and soil erosion in south Greenland over the past 700 years

“…The plant is not native to Greenland (Böcher et al, 1968) and, although morphologically-similar pollen is produced by plants present throughout central Europe from the Iron Age forwards, the most likely source for this pollen type is North America. Studies from eastern-central North America (Bassett and Terasmae, 1962;Gordon, 1966;Brugam, 1978;McAndrews, 1988;McAndrews and Boyko-Diakonow, 1989;Baker et al, 1993;Ireland et al, 2014) have demonstrated a rise in Ambrosia pollen coinciding with the arrival and expansion of European settlers. It seems that the introduction of intensive agricultural practices linked with forest clearance promoted the increase in Ambrosia-type pollen.…”