Pollen analysis of a new core from Joe Lake indicates that the late Qu
aternary vegetation of northwestern Alaska was characterized by four t
undra and two forest-tundra types. These vegetation types were differe
ntiated by combining quantitative comparisons of fossil and modern pol
len assemblages with traditional, qualitative approaches for inferring
past vegetation, such as the use of indicator species. Although impre
cisely dated, the core probably spans at least the past 40,000 yr. A g
raminoid-Salix tundra dominated during the later and early portions of
the glacial record. The middle glacial interval and the transition fr
om glacial to interglacial conditions are characterized by a graminoid
-Betula-Salix tundra. A Populus forest-Betula shrub tundra existed dur
ing the middle potion of this transition, being replaced in the early
Holocene by a Betula-Alnus shrub tundra. The modern Picea forest-shrub
tundra was established by the middle Holocene. These results suggest
that the composition of modem tundra communities in northwestern Alask
a developed relatively recently and that throughout much of the late Q
uaternary, tundra communities were unlike the predominant types found
today in northern North America. Although descriptions of vegetation v
ariations within the tundra will always be restricted by the innate ta
xonomic limitations of their herb-dominated pollen spectra, the applic
ation of multiple interpretive approaches improves the ability to reco
nstruct the historical development of this vegetation type. (C) 1994 U
niversity of Washington.