Ray, N. and J. M. Adams (2001).
"A GIS-based Vegetation Map of the World at the
Last Glacial Maximum (25,000-15,000 BP)"
Internet Archaeology 11

     Abstract
    "A preliminary, broad-scale vegetation map
     reconstruction for use by archaeologists and
     anthropologists is presented here for the
     world at the Last Glacial Maximum (18,000 BP,
     but broadly representing the interval from
     25,000 to 15,000 BP). The global LGM map was
     produced from a range of literature and map
     sources, and drawn on a GIS with topographic
     information. Extended coastlines due to LGM
     sea-level drop were obtained using
     bathymetric information."

The original is only accessible by subscribers
<http://intarch.ac.uk/journal/issue11/rayadams_toc.html>
but here is a minimal version with the maps
<http://www.ncdc.noaa.gov/paleo/pubs/ray2001/>
and the full 44 pp article is avialable for free
from there
<http://www.ncdc.noaa.gov/paleo/pubs/ray2001/ray_adams_2001.pdf>
[1.9 mb]

---------------------------------------------
Jonathan Adams
"Global land environments since the last interglacial"
<http://www.esd.ornl.gov/projects/qen/nerc.html>

North America during the last 150,000 years
<http://www.esd.ornl.gov/projects/qen/nercNORTHAMERICA.html>
(or click 'North America'on the main page)

qoutes concerning the key period

    "14,000 radiocarbon years ago.
     Indicators of a significant warming and
     moistening of climate begin to appear at
     around this time, but only in some areas.
     In Alaska, a widespread change from herb-
     dominated to moist shrub-dominated tundra
     occurred at around this time, suggesting
     moister and slightly warmer conditions
     (Andrews & Brubaker 1993.). A similar trend
     towards moister and warmer conditions is seen
     in the changing tundra flora and insect fauna
     on the eastern part of the Beringian land
     bridge (Elias et al. 1996).
     Further retreat of the Laurentide ice sheet
     had occurred, but the future ice-free
     corridor still remained blocked by around 800
     km of ice."

    "13,000 radiocarbon years ago.
     The vegetation distribution seems to have
     been much the same as at 14,000 14C years
     ago, though with continuing glacial retreat
     exposing new surfaces in North America. At
     around this time, a continuous ice-free
     corridor opened for the first time beween
     Alaska and the contiguous USA.
     However, for a considerable part of its
     length (about 750 km) it would have been less
     than 50 km wide, and further obstructed in
     several places by large meltwater lakes.
     The chronology of the first appearance of the
     ice free corridor is not completely settled
     however; although the southern and northern
     ends were open by this time, it is quite
     possible that the central region was still
     closed.

     However, conditions at the southern end of
     the ice-free corridor (e.g. in the area
     around 50-52 deg.N and 110-115 deg.W) still
     seem to have been fairly arid. Burns et al
     (1993) note the absence of radiocarbon dates
     on faunal remains between about 21,300 and
     11,600 14C y.a. in the Edmonton area,
     suggesting that the landscape was incapable
     of supporting fauna during this interval.
     Beaudoin suggests - on the basis of various
     pollen sites - that the vegetation in
     southern Alberta between about 16,100 to
     11,900 14C y.a. was a dry Artemisia-Betula
     shrubland."

Thomas Ager et al
"Ecosystem and Climate History of Alaska"
http://esp.cr.usgs.gov/research/alaska/index.html