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Definitions & Distinctions
Introduction
Ecological restoration is a valuable endeavor that has proven very difficult
to define. The term indicates that degraded and destroyed natural wetland
systems will be reestablished to sites where they once existed. But, what
wetland ecosystems are we talking about? How far back in time should we
go to find target ecosystems? Is establishing any type of wetland enough
to be called "restoration"?
Restorationists have considered these questions at length and addressed
them in the current definitions of restoration and restoration-type activities.
Several of these definitions are discussed in the sections below. A simple
and useful definition of restoration was developed by the National Research
Council (NRC). In its 1992 report, Restoration of Aquatic Ecosystems,
NRC defined restoration as the "return of an ecosystem to a close approximation
of its condition prior to disturbance." The concept of restoration is
further clarified by defining many types of restoration-related activities.
These activities, such as creation, reallocation, and enhancement, are
similar to restoration, but differ in some way from the process of renewing
native ecosystems to sites where they once existed.
Definitions for these terms have often been developed from an ecological
perspective and some of these are given in the section below, Definitions from the Restoration Literature. Recently, several
federal agencies agreed on refined versions of the ecologically-based
definitions in order to help them implement public policy. In particular,
these definitions are designed to help agencies accurately track wetland
losses and gains across the nation. These agency-developed definitions
are given below in the section, Federal Agency Definitions
for Wetland Tracking.
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Definitions from the Restoration Literature
What is Restoration?
The National Research Council (NRC)
 ,
in its 1992 report, Restoration of Aquatic Ecosystems, defined
restoration as the "return of an ecosystem to a close approximation of
its condition prior to disturbance." That report also states, "The term
restoration means the reestablishment of predisturbance aquatic functions
and related physical, chemical and biological characteristics (Cairns,
1988; Magnuson et. al., 1980; Lewis, 1989). Restoration is ... a holistic
process not achieved through the isolated manipulation of individual elements.
The holistic nature of restoration, including the reintroduction of animals,
needs to be emphasized ... Merely recreating a form without the functions,
or the functions in an artificial configuration bearing little resemblance
to a natural form, does not constitute restoration. The objective is to
emulate a natural, self-regulating system that is integrated ecologically
with the landscape in which it occurs. Often, restoration requires one
or more of the following processes: reconstruction of antecedent physical
conditions, chemical adjustment of the soil and water; and biological
manipulation, including the reintroduction of absent native flora and
fauna..."
The NRC report also advises: "Without an active and ambitious program
in the United States, our swelling population and its increasing stresses
on aquatic ecosystems will certainly reduce the quality of human life
for present and future generations. By embarking now on a major national
aquatic ecosystem restoration program, the United States can set an example
of aquatic resource stewardship that ultimately will also improve the
management of other resource types and will set an international example
of environmental leadership."
Gwin, et al. (1999) state that restoration requires knowledge of the
wetland type prior to disturbance; restoration has the goal of returning
the wetland to that type. However, Lewis (1989) notes that "it is not
necessary to have complete knowledge of what those pre-existing conditions
were; it is enough to know a wetland of whatever type was there and to
have as a goal to return to that same wetland...it is not necessary that
a system be returned to a pristine condition." He also finds that restoration
may occur when a degraded wetland is returned to a previous condition
of ecological functioning, although that previous condition may have also
been altered by human activity.
The Society for Ecological Restoration
(SER)
includes sustainable cultural activities, such as those practiced by indigenous
peoples, in its current definition of restoration. SER defines ecological
restoration as "the process of assisting the recovery and management of
ecological integrity. Ecological integrity includes a critical range of
variability in biodiversity, ecological processes and structures, regional
and historical context, and sustainable cultural practices."
There are also numerous restoration-related activities that differ in
some important way from the definitions given above.
What is Creation?
Creation is the "construction of a wetland in an area that was not a
wetland in the recent past (within the last 100-200 years) and that is
isolated from existing wetlands (i.e., not directly adjacent)" (Gwin,
et al., 1999). In other words, creation occurs when a wetland is placed
on the landscape by some human activity on a non-wetland site (Lewis,
1989). Typically, a wetland is created by excavation of upland soils to
elevations that will support the growth of wetland species through the
establishment of an appropriate hydrology.
What is Enhancement?
Gwin, et al. (1999) define enhancement as "the modification of specific
structural features of an existing wetland to increase one or more functions
based on management objectives, typically done by modifying site elevations
or the proportion of open water. Although this term implies gain or improvement,
a positive change in one wetland function may negatively affect other
wetland functions". Lewis (1989) also states that enhancement may also
be the alteration of a site to produce conditions that did not previously
exist in order to accentuate one or more values of a site. For example,
increasing the area of deep water by excavating parts of an emergent wetland
may provide more duck habitat (the desired wetland value), but may decrease
foraging and cover habitat for young fish.
What is Reallocation or Replacement?
These terms apply to activities in which most or all of an existing wetland
is converted to a different type of wetland. For example, changing an
emergent wetland to a pond converts the habitat from one wetland type
to something quite different.
What is Mitigation?
Mitigation, a term that frequently occurs in discussions of restoration,
"refers to the restoration, creation, or enhancement of wetlands to compensate
for permitted wetland losses" (Lewis, 1989). Under Section 404 of the
Clean Water Act, wetlands may legally be destroyed, but their loss must
be compensated for by the restoration, creation, or enhancement of other
wetlands. In theory, this strategy should result in "no net loss" of wetlands.
For a recent analysis of the effectiveness of wetland mitigation, see
articles by J. Zedler (1996) and M. S. Race and M. S. Fonseca (1996) in
the scientific journal, Ecological Applications.
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Federal Agency Definitions for Wetland Tracking
Introduction
The Federal Geographic Data Committee, Wetlands Subcommittee, composed
of several federal agencies, developed definitions for restoration
and related activities designed to aid agencies in accurately reporting
wetland increases due to their program activities. Many different definitions
of these terms have been used by various agencies. The definitions, below,
provide standard terminology for the more than 15 agencies involved in
wetland restoration, related activities, and/or mitigation.
Restoration: the manipulation of the physical, chemical, or biological
characteristics of a site with the goal of returning natural/historic
functions to former or degraded wetland. For the purpose of tracking net
gains in wetland acres, restoration is divided into:
- Re-establishment: the manipulation of the physical, chemical,
or biological characteristics of a site with the goal of returning natural/historic
functions to a former wetland. Re-establishment results in rebuilding
a former wetland and results in a gain in wetland acres.
- Rehabilitation: the manipulation of the physical, chemical,
or biological characteristics of a site with the goal of repairing natural/historic
functions of degraded wetland. Rehabilitation results in a gain in wetland
function, but does not result in a gain in wetland acres.
Establishment: the manipulation of the physical, chemical, or
biological characteristics present to develop a wetland that did not previously
exist on an upland or deepwater site. Establishment results in a gain
in wetland acres.
Enhancement: the manipulation of the physical, chemical, or biological
characteristics of a wetland (undisturbed or degraded) site the heighten,
intensify, or improve specific function(s) or for a purpose such as water
quality improvement, flood water retention or wildlife habitat. Enhancement
results in a change in wetland function(s) and can lead to a decline in
other wetland function, but does not result in a gain in wetland acres.
This term includes activities commonly associated with the terms enhancement,
management, manipulation, directed alteration.
Protection/Maintenance: the removal of a threat to, or preventing
decline of, wetland conditions be an action in of near a wetland. Includes
purchase of land or easement, repairing water control structures or fences,
or structural protection such as repairing a barrier island. This term
also includes activities commonly associated with the term preservation.
Protection/Maintenance does not result in a gain of wetland acres or function.
| Federal Geographic Data
Committee Wetlands Subcommittee members: |
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US Department of Interior |
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National Marine Fisheries Service (NOAA) |
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US Fish and Wildlife Service |
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National Aeronautical and Space Agency |
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Bureau of Land Management |
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Department of Energy |
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National Park Service |
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Tennessee Valley Authority |
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US Geological Survey |
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Army Corps of Engineers |
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Bureau of Reclamation |
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Department of the Army |
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Office of Surface Mining |
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US Marine Corps |
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Bureau of Indian Affairs |
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US Navy |
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US Department of Agriculture |
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US Air Force |
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Natural Resources Conservation Service |
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Office of Management and Budget |
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Forest Service |
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National Capital Planning Commission |
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Environmental Protection Agency |
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Department of Housing and Urban Development |
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References
Gwin, S.E., M.E. Kentula, and P.W. Shaffer. 1999. Evaluating the Effects
of Wetland Regulation through Hydrogeomorphic Classification and Landscape
Profiles. Wetlands 19(3): 477-489.
Lewis, R. R. III 1989. Wetland restoration/creation/enhancement terminology:
Suggestions for standardization. Wetland Creation and Restoration: The
Status of the Science, Vol. II. EPA 600/3/89/038B. U.S. Environmental
Protection Agency, Washington, D.C.
National Research Council. 1992. Restoration of Aquatic Ecosystems: Science,
Technology and Public Policy. National Academy Press, Washington, D.C.
Race, M. S. and M. S. Fonseca. 1996. Fixing compensatory mitigation:
What will it take? Ecological Applications 6(1):94-101.
Society for Ecological Restoration website
Zedler, J. 1996. Ecological issues in wetland mitigation: An introduction
to the forum. Ecological Applications 6(1):33-37.
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