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

e expected to cause more drastic fluctuations in
wetland surface-water levels, especially where
the wetlands are located in isolated basins with
restricted outlets. The greater fluctuation and
generally greater volume of surface water entering
the wetland may reduce plant productivity
and eventually change both the structure and
species composition of the plant community; wildlife
habitat values may be seriously affected as
well. Without proper management of runoff in
major land development projects, swamps receiving
such waters may become little more than
detention basins.
Stonnwater runoff may introduce a wide variety
of pollutants into wetlands. Highways, parking
lots, cropland, animal feedlots, landfills, and
sludge disposal sites are some of the land uses that
may contribute significantly to surface-water pollution
of wetlands. Among the various pollutants
are road salt; oil, grease, gasoline, and other petroleum
products; suspended sediment; fertilizers;
pesticides; heavy metals; and chlorinated hydrocarbons.
Runoff from landfills may contain a
variety of hazardous wastes. The effects of many
of these pollutants on red maple swamps is unknown,
but it is highly likely that the accumulation
of such substances in wetland soils adversely
affects plant growth, invertebrate life in the soil
and in surface waters, amphibians, and other
forms of wildlife higher in the food chain. Ehrenfeld
(1983) demonstrated increased flooding and
si&icant changes in plant species composition
and water chemistry in southern New Jersey
swamps receiving runoff from urbanized areas.
Discharges of wastewater from sewage treatment
facilities or from various industries may
have major adverse effects on wetlands. The effects
on wetland hydrology and water quality are
similar to those from stoqnwater runoff, but often
much more pronounced because of the greater
volume of water discharged, the greater concentration
of pollutants in the water, and more sustained
discharge.
Alteration of Surrounding Uplands
Human activities in upland areas immediately
adjacent to red maple swamps (Fig. 8.2) also may
adversely affect the functions and values of those
wetlands. Clearing of natural vegetation, reduction
of groundwater recharge through paving, and
installation of belowground sewage disposal systems
are common examples.
Natural, undisturbed surroundings may meet
some of the habitat requirements of wildlife residing
in wetlands. They may help to buffer the direct
impacts of human activity (e.g., noise) on wetland
wildlife, and may serve as the primary habitat for
species such as salamanders, which use swamps
for breeding. Clearing of vegetation and other
land disturbance near the wetland edge may have
a major adverse effect on the value of the wetland
to wildlife. Unless provisions are made to artificially
recharge the groundwater system when
large tracts of land are paved, local water tables
may drop in the developed area, which, in turn,
may reduce the quantity and duration of groundwater
flow to adjacent wetlands, lowering wetland
water levels as well. Despite increases in surfacewater
runoff reaching the wetland, average summer
water levels may drop below normal if
groundwater inflow formerly was an important
component of the wetland's water budget.
Finally, the installation of belowground septic
systems near the wetland edge may degrade
water quality in wetlands and associated water
bodies, particularly if upland soils are low in permeability
or have high water tables. Either of
these conditions may cause effluent to discharge
in the wetland. Septic systems sited close to wetlands
in soils with excessively high permeability
also represent a significant water-quality threat
because of the speed with which effluent can flow
toward the wetland, even if the system is properly
maintained.
Key Management Issues
Through the regulation of land use in and
around northeastern inland wetlands, federal,
state, and local regulatory agencies and commissions
have assumed the role of wetland resource
managers. It is their responsibility to maintain
the natural functions and values of wetlands, to
prevent wetland loss and degradation, to protect
the public from the hazards of development in
wetlands, and, in some cases, to mandate restoration
of wetlands that have been altered. The task
of safeguarding the public interest in wetlands is
beset with practical, technical, and philosophical
problems. ResoluLiorl of these problems is hindered
not only by agency staff and budget limitations,
but also by a dearth of scientific data on
wetland characteristics and values, and a lack of
standard procedures for addressing tasks such as
wetland identification and delineation, the as-