Parallel climate and vegetation
responses to the early Holocene collapse
of the Laurentide Ice Sheet.
Bryan Shuman, Patrick Bartlein,
Nathaniel Logara, Paige Newby, Thompson
Webb III (2002).
Quaternary Science Reviews 21: 1793–1805.
Abstract:
Parallel changes in lake-level and pollen
data show that the rapid decline of the Laurentide Ice Sheet (LIS) between
10,000 and 8000-and-nbsp;cal-and-nbsp;yr BP triggered a step-like change in North
American climates: from an ice-sheet-and-insolation-dominated climate to a
climate primarily controlled by insolation. Maps of the lake-level data from
across eastern North America show a reorganization of climate patterns that the
pollen data independently match. Raised lake-levels and expanded populations of
moist-tolerant southern pines (Pinus) document that summer monsoons intensified
in the southeastern United States between 9000 and 8000-and-nbsp;cal-and-nbsp;yr BP.
Simultaneously, low lake-levels and an eastward expansion of the prairie
illustrate an increase in mid-continental aridity. After the Hudson Bay ice dome
collapsed around 8200-and-nbsp;cal-and-nbsp;yr BP, lake-levels rose in New England, as
populations of mesic plant taxa, such as beech (Fagus) and hemlock (Tsuga),
replaced those of dry-tolerant northern pines (Pinus). Available moisture
increased there after a related century-scale period of colder-than-previous
conditions around 8200-and-nbsp;cal-and-nbsp;yr BP, which is also recorded in the pollen
data. The comparison between pollen and lake-level data confirms that
vegetations dynamics reflect climatic patterns on the millennial-scale.