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

Fig. 8.3. Southern New England red mapIe swamp cIeared for cranberry bog expansion.
Construction of Impoundments
Major impacts to vegetated wetlands occurred
when thousands of dams were constructed on
northeastern streams for hydropower, industrial
and public water supply, flood control, and recreation.
Where impoundments were small, and associated
streams were high-gradient, the losses of
wetland probably were small at any single site,
but the cumulative impacts of these darns must
have been considerable. Where constructed lakes
were large, such as Flagstaff Lake in Maine, thousands
of hectares of swamp were inundated (Widoff
1988). Widoff estimated that losses of vegetated
wetland to impoundments in Maine may
exceed 12,000 ha, nearly 30% of the total wetland
loss-second only to wetland losses from urbanization.
Tiner (1985) listed reservoir construction
as a major cause of wetland loss in New Jersey as
well. In trend analysis studies of wetlands in
southeastern Massachusetts (Larson et al. 1980;
Tiner and Zinni 19881, construction of impoundments
was found to be responsible for about 15%
of vegetated wetland losses. The principal functions
of these water bodies were municipal water
supply and water storage for irrigation of cranberry
bogs.
Nighway Construction
Although road construction can be considered
one facet of urbanization (see below), it is treated
separately here because of its importance. Highway
construction represents one of the most significant
causes of wetland alteration in the Northeast, both
directly through wetland filling and draining, and
indirectly by improving access to formerly isolated
areas and thus stimulating secondary incursions
into wetlands. Construction of interstate highways
through northern New Jersey, for example, bas
filled large areas of wetland and, at the same time,
fragmented major wetland complexes, permitting
the continued expansion of the New Yorkmetropolitan
area (Tmer 1985). This same phenomenon can
be observed in the vicinity of any of the major urban
areas in the Northeast.
In rural areas, filling due to highway construction
may represent one of the primary causes of
wetland loss. Road-building was the most frequent
type of impact identified in a random survey
of 100 Vermont wetlands (Wanner 1979). Between
1951 and 1971, nearly 30 ha of inland wetland
were directly lost to road construction in Bristol
County, Mass.; another 36 ha of wetland were
converted from one wetland type to another as the
new roads altered wetland water regimes (Larson
et al. 1980). In South Kingstown, R.I., road construction
accounted for almost 4@/0 of the wetland
loss between 1939 and 1972 (Golet and Parkhurst
1981). In Maine, Widoff (1988) estimated that
roads were responsible for about 1@!o of the state's
total wetland loss.