Ecology of Red Maple Swamps in the Glaciated Northeast: A ...

Fig. 8.4. Electric utility lines passing through a former red maple swamp. Forested swamp flanks the
pwerline on either side while shrub swamp dominates the right-of-way.
agricultural purposes. In northeastern Connecticut,
red maple swamps were sometimes clear-cut
for fuelwood during the first half of the twentieth
century (Grace 1972).
Clearing of forested wetland for utility rights-ofway
is a major form of alteration that is growing in
importance throughout the Northeast (Fig. 8.4). In
a sample of 100 Vermont wetlands surveyed in
1974,14% had been affected by transmission lines
(Wanner 1979). The impacts of cutting usually are
compounded by wetland faing for the construction
of power line maintenanm roads.
The degree of impact of timber removal on
wetland functions and values depends on the intensity
of cutting. Clear-cuts radically alter habitat
values and may result in slightly higher water
levels during the summer because of reduced transpiration
losses; selective cutting may have far
less impact. Timber harvesting for wood products
is not currently a major form of alteration in red
maple swamps, but increasing energy costs and
elimination of upland forests by urbanization may
heighten the importance of this activity in the
future.
Water Level Manipulation
Human-induced changes in the water regime of
a red maple swamp may have major impacts on the
floristic composition and structure of the plant community,
its habitat values, and its scenic and recreational
values. Prior to the passage of wetland
protection regulations, changes in wetland water
regimes were a common consequence of highway
construction. Culverts that were inwmt1y designed,
improperly installed, or omitted altogether
fkequently resulted in impoundment of water on
the upstream side of the road and a reduction in
surface-water flow to the downstream side. Such
impoundment commonly converted red maple
swamps to marshes or shrub swamps. These impacts
are less common today where wetland regulations
are strictly enforced; however, sediment accumulation
in culverts under roads may cause
gradual changes in wah~egimes the same
ultimate result (Golet and Parkhurst 1981). Nearly
Wh of the human-induced changes in inland wetlands
of South Kingstown, R.I., between 1939 and
1972 were retrogressive; raised water levels were
the eause in most cases.
+%