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

sessment of wetland functions and values, impact facultative species along the entire length of most
assessment, and mitigation. The following discus- wetland-to-upland transects obscured moiatnresion
highlights some of the key management is- related gradients in vegetation. For thia reason,
sues affecting red maple swamps in the glaciated the shrub layers were found to be of little value in
Northeast.
locating a wetland-upland vegetation break. hal
variations in surface elevation and soil properties
Boundary Delineat ion
often caused the status (wetland vs. upland) of
contiguous sample plots to alternate, even in the
Wetland identification and delineation are a
herb layer; in such inatanees, the boundcritical
first step in the regulatory process. This
ary was more aptly represented as a zone, rather
step determines which parcels of land are subject
than a line. Boundary zones derived from herb
to regulation and defines the area within which
layer data ranged in width from to 46
values and environmental effects will be assessed.
The development of standard hydrologic criteria
In some instances, the transition from wetland to
for wetland delineation is probably unfeasible beupland
is abmpt? the changes in vegetation
cause of the complex variability in hyhlogic mnsoils
are obvious, and the location of the wetland
ditions over time and the lack of long-tem
boundary is subject to little debate. In other cases,
urements at specific sites. As already noted,
where the slope of the moisture gradient is gradboundary
determination using only vegetation
ual, no well-defined break may be The may difficult to achieve in mw red maple
task of boundary location is especially difficult in
swamps because of the high proportion of facultamany
red map1e swamps because the dominant
tive species. For these reasom, it see- appropnplants
in the swamps are usually facultative speate
to major emphasis on the
ties FACW FAC, or FAcU) that also grow in the
of soil in the delineation of red maple swamps
adjacent uplands. Swamps located on hillsides or
(Allen 1989). This conclusion is consistent with the
over perched groundwater Pose a particu- hierarchy of decisions in the fihral Manual for
lar problem because changes in surface elevation
and Delinwting Jurisdictional Wetmay
not directly correspond to variations in soil lands (Federal Interagency Committee for Wetmoisture.
land Delineation 1989). In the Northeast, most
"Multiparameter" approaches to wetland de- hy&ic soils are very poorly drained or poorly
lineation (e.g., Environmental Laboratory 1987;
drained (Tiner and Veneman 1987). Consistent
Federal Inkragency CoKUnittee for Dc- inclusioIl of these two drainage classes of
lineation 1989) generally assume that vegetation, within regulated wetlands is logical also from
soils, and hydrologic criteria are perfectly corre- of functions and values and
lated. Actually, empirical data on relations among hazards to development.
these three classes of variables are lacking for most
wetland types (Allen et al. 1989). Even if the crite- Mitigation by Replacement or
ria set forth in a particular method are strongly
Enhancement
correlated, the accuracy of the method will be
limited, if only because the criteria themselves are Since the mid-1980's, the term "wetland mitigagross
simplifications of nature (Scott et al. 1989). tion" has become synonymous with wetland re-
Allen et al. (1989) tested the agreement between placement or enhancement (Golet 1986). Replacethe
hydric status of soils, as determined from the ment entails the creation of new wetland from
national hydric soils list (U.S. Soil Conservation upland to compensate for the wetland destroyed in
Service 1987), and the average wetiand i~ldicator a particular project. Enhancement proposals genstatus
(Reed 1988) of plants growing in the transi- erally seek to compensate for wetland losses by
tion zones of three Rhode I sland red maple changing a remaining part of the wetland that is to
swamps. They found that herb layer vegetation be altered, or changing a nearby wetland, in a
exhibited the most clearly defied moisture gradi- manner that enhances certain functions or values.
ent, correlated best with hydric soil status, and For example, conversion of one area of forested
permitted the most precise discrimination be- wetland to marsh by artificially raising the water
tween upland and wetlad. A moisture-related level might be proposed as a means of increasing
gradient was reflected in the tree layer also, but it the wetland's value for waterfowl and cornpensat-
was not as consistent as in the herb layer, In the ing for the fiiiing of a second area of wetland for
two shrub layers examined, the predominance of development purposes. Mitigation by replacement