Biology Reference
In-Depth Information
Table 8.1.
Pollen zone sequence and inferred vegetation and climate for the
New England region
Pollen zones
Years BP
Vegetation
Climate
C-3
Present
Oak-chestnut-hemlock
Moister, cooler
(
Ambrosia, Rumex
, other
weeds)
C-2
Oak with hickory
Warm, dry
C-1
7900
Oak-hemlock, some
Warm, moist
Ambrosia
B
7900-8100
Pine maximum with oak
Warm, dry
A-4
9100-10,200
Spruce-fi r with larch,
Cooler, moister
birch, alder
(Younger Dryas)
A-3
10,200
Spruce-oak with pine
Warmer, drier
A-2
11,700
Spruce with oak
A-1
11,700-12,150
Spruce, fi r, birch
Cool, moist
T
12,150-14,300
Tundra
Cold, dry
Sources:
Various sources from Graham (I, 289)
This is the general pattern of ecosystem change within the glacial boundary
in northeastern North America.
In the Appalachian region beyond the glacial boundary, coniferous for-
est occupied much of the highlands during each cold interval, while many
of the thermophilous deciduous elements moved onto the coastal plain and
to the southwest toward the Ozark and Edwards plateaus. Thus, in refer-
ring to the Appalachian highlands as an ancient (Tertiary) relictual area for
the deciduous forest, it is necessary to recognize that in the Quaternary
the regional ecosystems were undergoing considerable change in distribu-
tion and in composition at the level of associations. On the coastal plain
of Georgia at 13-11 kyr, during the Younger Dryas, there was mesic for-
est and reduced pine, while after about 4.5 kyr drier conditions and fi re
resulted in an increase of southern pine (LaMoreaux et al. 2009). Farther
beyond the glacial boundary, a pollen diagram from Lake Tulane in south-
central Florida shows fi ve peaks in pine pollen that correspond to Heinrich
events H1-H5 (Grimm et al. 1993; Watts and Hansen 1994). It raises the
question that if Quaternary climate and vegetation changes extended this
far beyond the glacial boundary, how much farther south did they extend?
As noted earlier, the answer is across the equator and all the way from
pole to pole.
