Fe. Mayle et al., ALNUS AS AN INDICATOR TAXON OF THE YOUNGER DRYAS COOLING IN EASTERN NORTH-AMERICA, Quaternary science reviews, 12(5), 1993, pp. 295-305
The Younger Dryas cold interval (ca. 10.8-10 ka BP) in eastern North A
merica has been documented throughout Atlantic Canada a parts of north
eastern U.S.A. Due to differences in latitude and elevation between ma
ny of these sites, there is considerable regional variation in the nat
ure of Younger Dryas pollen changes. However, there is a consistent pe
ak in alder pollen percentages (generally 10-20%) at all these sites:
A. crispa in Atlantic Canada and highland regions of northeastern U.S.
A. and A. rugosa-type in lowland areas of New England. Macrofossil and
pollen influx data show that the alder pollen percentage peak can be
attributed to local and/or regional presence of alder populations at t
his time at several New England sites. The ecological significance of
the Younger Dryas alder pollen percentage peak in Atlantic Canada is m
ore difficult to explain. Evidence for two possible interpretations is
discussed: (i) regional expansion of alder populations in the area, a
nd (ii) alder populations were absent in Atlantic Canada at this time
and the pollen originates from distant populations in New England.