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Coastal Ecosystem Restoration
Imagine you are in charge of a coastal restoration project. The goals are to reopen a tidal channel that was blocked by a build-up of beach sands more than 8 years ago and to restore the marsh to which it was once connected. Within 5 years, you expect to have restored the marsh from a fresh/brackish pond with infrequent tidal inputs and a growing population of the invasive plant species, Phragmites australis, to a high-salinity emergent wetland similar to a reference marsh, where native plant species thrive. Instead, 2 years after the tidal channel was reopened, your monitoring indicates that although the fresh water is gone, the P. australis has not decreased in distribution or abundance. What would you do? Can you expect to leave the system alone and still obtain the project goal, or do you need to make some adjustments that will help the project to succeed? One of the most significant developments in aquatic system restoration and project management has been the increased use of adaptive management principles to assess the success of a restoration project at a particular point in time based on monitoring-program results, and then to make adjustments that are likely to improve overall project success. The process can be repeated as many times as necessary to keep the project on track toward meeting all of its objectives (Figure 1). It is important to be able to modify management of an ongoing project, because it allows a manager to consider how such things as new knowledge from outside the project, new technology, inventories, and adjustments to performance goals could affect the project. The ultimate goal is to make a project "work" and not to waste funds by attempting to adhere to inflexible and unrealistic goals.
Application of adaptive management strategies calls for significant planning and assessment before any construction begins. To allow measurement of the progress made toward the restoration goals, it is important to evaluate all the characteristics that are to be improved, as well as the initial biological, physical, and chemical components of the project site before any change takes place. Setting specific goals and measurable objectives for the restoration project is critical. It is more difficult to evaluate the success of a project when its goal is stated broadly, such as "to restore the native plant community," than it is to do so when the goal is clearly defined, such as "to decrease distribution of Phragmites australis by restoring tidal hydrology, thereby increasing porewater salinity and reducing standing freshwater ponds." When the objectives are defined before the project begins, it simplifies the development of a monitoring plan that will be able to measure progress directly. The monitoring program is used as a tool to assess the potential for success and identify any problems that might affect progression toward the project goals. Broadly speaking, the options available to the manager are no action, maintenance of the system, and modification of the project goals. If the monitoring program identifies deviation from the predicted trajectory (Figure 2) of ecosystem development, adjustments can and should be made. For example, a project goal might be to eradicate an exotic plant and increase native marsh vegetation through changes in hydrology. If monitoring showed that the exotic was still dominant after a period of time then additional restoration actions might be employed, such as exotic removal and native species plantings. Adaptive management has been recommended at a national level and is in use on many major restoration projects. After goals and objectives are set, a matrix can be created to delineate
the expected progression of the restoration project over time, and to
predict other alternative states that the restored system could potentially
exhibit (Figure 3). This can help a project manager in various ways.
For example, when monitoring results indicate that the restoration does
not match the expected progression, the matrix may provide an explanation
for the situation. The manager can then make a decision to delay action
if it is anticipated that the progress will be self-correcting, or alternatively,
the manager might find support for recommending or taking action. This
process of planning, acting, monitoring, evaluating, and adjusting is
the essence of adaptive management. The key to adaptive management
is recognizing that there will always be uncertainties about the interdependencies
within and among natural and social systems. Instead of relying on a
fixed goal for restoration and an inflexible plan for achieving the
goal, adaptive management allows for midcourse corrections. Restoration
project managers should be encouraged to practice preplanning and to
cultivate advanced awareness of potential problems and their solutions;
as a result, stakeholders can be asked in a timely manner to set aside
funds for responding to project setbacks, thereby maintaining the restoration
schedule.
Case Study: Adaptive Management in One Rhode Island ProjectThe scenario introduced at the beginning of this section is based
on real events. To see how adaptive management is used in coastal restoration
projects, we will follow the continual evaluation process shown in Figure
1 (plan, act, monitor, evaluate, adjust) for a restoration project in
Rhode Island. PLAN (prerestoration)
The Barrington Land Conservation Trust (the Trust) owns a coastal marsh along Little Mussachuck Creek in Barrington, Rhode Island (Figure 4). In the early 1990s, a natural breachway through the barrier beach was closed off due to sand deposition. This breachway, which used to connect the marsh to the Providence River, allowed for the daily flushing of the marsh by tidal waters. Once cut off from tidal flows, the marsh increasingly became a freshwater habitat. This change in marsh hydrology allowed the invasive plant species, P. australis , previously located only around the fringe of the marsh, to expand quickly into the marsh (Figure 5 ). The primary concern regarding this expansion is that P. australis could outcompete and replace rare native brackish marsh plants, such as Eleocharis rostellata (creeping spikerush), Suaeda maritima (maritime sea blite) (Figure 6) and Scirpus robustus (robust bulrush). Together with the group, Save the Bay, the Trust began working toward a restoration goal: to restore tidal hydrology to the northern marsh and pond complex by excavating connector channels to an existing tidal channel draining the southern inlet. The desired outcomes were as follows:
As part of the planning process, a matrix can be developed that characterizes potential outcomes and formalizes the project criteria. Such a matrix shows early stages of development in the lower left corner and proceeds to a fully restored system at the upper right (Figure 2). As an example, Figure 7 portrays a matrix for the Little Mussachuck Creek Marsh project that has been simplified to show only the effects of an increase in porewater salinity (i.e., ecosystem structure) on the recolonization of native vegetation (i.e., ecosystem function). When additional parameters are factored in the matrix can get more complex, or separate matrices can be developed to depict the desired ecosystem structure and functions. This type of matrix is used in "passive adaptive management," in which
a single response model is selected upon which decisions are based.
It is assumed, but not always rightly so, that the model is correct. ACT (Year 1)
Several technical experts visited the site in 1997 and then made recommendations
on the best ways to restore the marsh. A preferred alternative was chosen
by the restoration team, and engineering plans were developed. The restoration
groups applied for and received the necessary permits for the project,
and obtained grant funding to purchase construction and monitoring equipment.
Volunteers were organized, and in April 1998, the volunteers dug the
new channels and re-established tidal flow to the Providence River (Figure
8). MONITOR (Years 1-2)Save The Bay, the Trust, and Brown University's Geological Sciences
Program partnered to conduct post restoration monitoring. Their goal
was to monitor the biological and chemical characteristics of the marsh
as the natural succession of plants and wildlife occurred for 5 years.
Monitoring included permanent transects to track changes in plant species'
richness, as well as the relative abundance and vigor of P. australis.
Salinity monitoring of surface water and porewater (groundwater) was
also carried out by trained volunteers. Surveys were planned to cover
each growing season. EVALUATE (Year 2)After 2 years of monitoring, the measurements indicated the following:
Thus, the desired outcomes 1-3 were achieved, outcome 4 was not, and
outcome 5 was partially attained. Successfully opening the channel decreased
the amount of standing surface water, which allowed native plants to
colonize mudflats. It increased salinities at the sampling sites, and
allowed a more natural tidal hydrology. However, there was no evidence
to indicate that P. australis was decreasing in its distribution. ADJUST (Year 2)After 2 years, the progress of the project was best described by the
middle box at the far right of the matrix (Figure 6). The desired salinity
had been reached, but the invasive plant was still threatening native
plant populations. However, because native plants were successfully
recolonizing the restored tidal mud flats, it was decided that no immediate
action would be taken and that monitoring would continue through 2002,
when the restoration groups would reevaluate the situation. PLAN, ACT, MONITOR (Years 3-4)Plans were made to adjust the monitoring plan and schedule, making them more easily accessible to available experts and volunteer resources. Some of the intensive vegetative sampling was postponed until 2002. As an alternative, permanent photo stations were set up as a simple, yet effective way to monitor long-term changes in the marsh. Although annual assessments are recommended for most projects, monitoring should be conducted at a frequency and for a duration most appropriate for the project, which can range from very short (e.g., every hour) to much longer (e.g., once every 2 years). An attenuated monitoring schedule may be appropriate if change is slow. Monitoring guidelines for Rhode Island salt marsh restoration projects
had not been developed at the time of the restoration. An effort is
underway to develop statewide restoration monitoring guidelines similar
to those developed for the Gulf of Maine (http://www.edc.uri.edu/restoration/html/resource/gpac.pdf)
and New York State (http://www.edc.uri.edu/restoration/html/resource/nymarsh.pdf). ADJUST (Year 4)In 2002, the project managers re-evaluated the performance of the
restoration activities. Progress of the project was still best described
by the matrix in the middle box on the far right (Figure 6). Because
the P. australis population was still increasing, it was determined
that adjustments would have to be made, if the objectives of the project
were to be met. Decreasing the distribution of P. australis could
be undertaken with other control methods, including dredging, seasonal
mowing, use of plastic barriers, and burning. In addition, erosion in
the tidal channel indicated that there was a need to maintain or enhance
the existing tidal inlet. New plans were developed for 2003 to move
the restoration process toward the goals outlined in the upper right-hand
box in the matrix (Figure 6). SummaryRestoring ecosystems is a complex undertaking. By documenting a project from start to finish, we are able to learn from our mistakes as well as from our successes. Adaptive management principles directly address this type of situation and are applicable across the entire spectrum of coastal habitats that could be considered for restoration, including the water column, hard and soft bottom, coral reefs, oyster beds, macroalgae and kelp, soft and rocky shoreline, submerged aquatic vegetation, marsh, mangroves, deep-water swamps, riverine forests, and streams. For others to learn from a restoration project's success or failure, the knowledge gained through monitoring and social policies must be translated into restoration policy and program redesign. Whereas adaptive management is usually applied at a project-specific level, its principles may also be applied programmatically to large-scale studies, such as those under the Coastal Wetlands Planning, Protection, and Restoration Act (CWPPRA). In summary, Davis and Ogden (1994) encapsulate the philosophy behind adaptive management as follows: Because of the changing conditions and uncertainties, ecosystem stability
can only be viewed as a short-term objective. Long-term restoration
must be an ongoing process whereby restoration implementation becomes
a continuing series of management decisions. Each decision should be
based upon a growing pool of research information, updated measurements
of ecosystem responses, and evaluations of degrees of progress in reaching
a set of goals or targets that have been identified as indicative of
ecosystem vitality. ReferencesCairns, Jr., J. 1990. "Gauging the Cumulative Effects of Development Activities on Complex Ecosystems." Lewis. Chelsea, MI, Pages 239 to 256. Davis, S.M., and J.C. Ogden. 1994. "Toward ecosystem restoration." In: Everglades: The Ecosystem and its Restoration. Davis, S.M., and J.C. Ogden, eds. St. Lucie. Boca Raton, FL. Pages 769 to 796. Forest Ecosystem Management Team (FEMAT). 1993. Forest ecosystem management: An ecological, economic, and social assessment. U.S. Department of Agriculture. Washington, D.C. Hennessey, T.M. 1994. "Governance and Adaptive Management for Estuarine Ecosystems: the Case of Chesapeake Bay." Coastal Management. Volume 22. Pages 119 to 145. Kentula, M.E., and others. 1992. An Approach to Improving Decision Making in Wetland Restoration and Creation. U.S. Environmental Protection Agency. Corvallis, OR. National Research Council. 1992. Restoration of Aquatic Ecosystems. National Academy Press. Washington, DC. Raynie, R.C., and J.M. Visser. 2002. CWPPRA Adaptive Management Review, Final Report. Prepared for the CWPPRA Planning and Evaluation Subcommittee, Technical Committee, and Task Force. Available online at: http://www.lacoast.gov/reports/program/amrfr/FINAL%20REPORT%2012-20-02.pdf. Simenstad, C.A., and R.M. Thom. 1996. "Functional Equivalency Trajectories of the Restored Gog-Le-Hi-Te Estuarine Wetland." Ecological Applications. Volume 6, Number 1. Pages 38 to 56. Steyer, G.D., and D.W. Llewellyn. 2000. "Coastal Wetlands Planning, Protection, and Restoration Act: a Programmatic Application of Adaptive Management." Ecological Engineering. Volume 15, Numbers 3-4. Pages 385 to 395. http://www.elsevier.nl. Steyer, G.D., and others. 2002. "A proposed Coast-wide Reference Monitoring System for Evaluating Wetland Restoration Trajectories in Louisiana." Journal of Environmental Monitoring and Assessment. Volume 81. Pages 107 to 117. Steyer, G.D., and others. 1995. Quality management plan for Coastal Wetlands Planning Protection, and Restoration Act monitoring program. Open-file series. Louisiana Department of Natural Resources. Baton Rouge, LA. http://www.lacoast.gov/cwppra/reports/monitoringplan/qaqcpub.frt.htm. Thom, R.M. 1997. "System-Development Matrix for Adaptive Management of Coastal Ecosystem Restoration Projects." Ecological Engineering. Volume 8. Pages 219 to 232. Thom, R.M. 2000. "Adaptive Management of Coastal Ecosystem Restoration Projects." Ecological Engineering. Volume 15, Numbers 3-4. Pages 365 to 372. http://www.elsevier.nl. Toth, L.A. 1995. Principles and Guidelines for Restoration of River/Floodplain Ecosystems — Kissimmee River, Florida. Lewis. New York, NY. Pages 49 to 73. U.S. Army Corps of Engineers. 2000. Engineer regulation 1105-2-100, Planning guidance notebook. Washington, D.C. Walters, C.J. 1986. Adaptive Management of Renewable Resources. McGraw-Hill. New York, NY. Walters, C.J., and R. Holling. 1990. "Large-Scale Management Experiments and Learning by Doing." Ecology. Volume 71. Pages 2060 to 2068. Yozzo, D., J. Titre, and J. Sexton. 1996. Planning and Evaluating Restoration of Aquatic Habitats from an Ecological Perspective. U.S. Army Corps of Engineers. Alexandria, VA. Zedler, J.B. 1996. Tidal Wetlands Restoration: A Scientific Perspective and Southern California Focus. Additional information and citations are available in: Diefenderfer, H.L., and R.M. Thom. 2003. Systematic Approach to
Coastal Ecosystem Restoration. Prepared for: NOAA Coastal Services
Center. Charleston, SC. by Battelle Marine Sciences Laboratory. Sequim, WA. Glossaryporewater salinity — salinity of the water found
in the tiny spaces between soil particles |
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