bottomland swamps in the Southeast 
will be drained, deforested, and 
planted in soybean fields by 1990. If, 
over the next several decades, the pro- 
ductivity of commercial forests re- 
mains at 1977 levels and the land area 
now occupied by virgin forest remains 
constant but the area of secondary 
forest decreases by as much as 10 
percent, then the southeastern biota 
could return to being a source for at- 
mospheric carbon. Even if the bot- 
tomland forests continue to be cut, 
continued reforestation of unused 
cropland in other portions of the region 
might compensate for the loss. 
The historical patterns of change 
in the carbon cycle in the Southeast 
have been repeated elsewhere in the 
eastern United States, with certain re- 
gional differences. Between 1700 and 
1850, the rates of carbon loss par- 
alleled settlement patterns, with the 
most rapid and intense losses occur- 
ring within the original thirteen colo- 
nies. Between 1850 and 1900, farm 
abandonment and reforestation in 
New England — particularly Massa- 
chusetts, Rhode Island, and Connec- 
ticut — followed the initial land clear- 
ance, creating a temporary sink for 
carbon there. 
In the area of the Midwest extend- 
ing from Minnesota to Ohio, the mag- 
nitude and rate of carbon loss was 
greatest between 1850 and 1900. In 
the Great Lakes region, the logging 
of valuable stands of white pine (Pinus 
strobus) was succeeded by severe 
slash fires that liberated great quan- 
tities of carbon over a relatively short 
period of time. The depletion of soil 
carbon that resulted from such fires, 
for example, in the north of Michi- 
gan’s Lower Peninsula, reduced soil 
fertility on < sandy outwash plains, 
thereby prolonging forest recovery. 
From 1900 to 1950, loss of carbon 
was widespread and rapid throughout 
the East, but overall, since 1950, the 
eastern United States has been a car- 
bon sink, with only heavily agricul- 
tural states continuing to lose carbon 
each year. A wedge of low carbon 
The American chestnut, devastated 
by blight in the early 1900s, was once 
a dominant species in the southern 
Appalachians. The present forest of 
smaller trees has less biomass and 
can store less carbon. 
Forest History Society 
values extends from Iowa and north- 
ern Missouri into Illinois, Indiana, and 
Ohio, corresponding to the cultivated 
land of the Corn Belt. Elsewhere in 
the East, recovery has been substan- 
tial. Furthermore, this trend toward 
carbon gain has been occurring during 
the last three decades throughout the 
temperate region of the Northern 
Hemisphere. An analysis of forest in- 
ventory data from the United States, 
Canada, Europe, and Asia, by T. V. 
Armentano of the Institute of Ecology 
and C. W. Ralston of Duke University, 
has shown that this current temperate- 
zone carbon sink has amounted to be- 
tween 20 and 60 percent of the annual 
carbon released from the combustion 
of fossil fuels. Thus, forest recovery 
in the temperate zone has apparently 
at least slowed the increase in atmos- 
pheric carbon dioxide caused by the 
combustion of fossil fuels and the de- 
forestation of the tropics. 
The forests of eastern North Amer- 
ica, which were a carbon source for 
most of the past 250 years, constitute 
25 percent of the forests in the world’s 
temperate zone and are at present one 
of the principal carbon sinks in that 
zone. But the levels of atmospheric 
carbon continue to rise. Regional stud- 
ies of changing land-use patterns il- 
lustrate the spatial and temporal com- 
plexities involved in the storage and 
the exchange of carbon between the 
atmosphere and vegetation and soil. 
As we gain an appreciation of the 
magnitude and direction of the 
changes, we are beginning to develop 
a basis for sound management of for- 
ests, which play such an important 
role in the global carbon cycle. □ 
38 
