Primary purpose
To evaluate salt marshes and wetlands that were formerly tidal for community planning, providing baseline information for future restoration efforts, and identifying areas that may need increased protection measures. NBM is not designed for use in detailed impact analysis on individual wetlands.
Expertise needed
Individuals who have some knowledge of tidal marshes (e.g., local citizen groups, municipalities, and concerned individuals), but not necessarily wetland ecologists.
Applicable habitat types
Tidal salt marshes and brackish/freshwater wetlands that were formerly tidal in Narragansett Bay, RI.
Categories assessed
Three categories are addressed: ecological health of the zone of influence; ecological health of a salt marsh; and tidal restrictions.
Procedure
The user(s) identifies the marsh formation type (meadow marsh or fringing marsh) and divides the marsh system into evaluation units (EUs) based on observed tidal restrictions. Previously tidal adjacent wetlands are also included in the evaluation. Each EU is evaluated separately by completing data sheets that (a) contain questions, (b) list criteria for each question, (c) assign a value (scale 0-4) for each criteria, and (d) include a space for comments. The entire marsh is also evaluated for tidal restrictions. Responses to all questions are simply recorded. The data are entered into spreadsheet and GIS databases. There is no procedure for combining responses to derive other indices or scores.
Key Terminology
Ecological health: a report on the extent of the alteration to a natural salt marsh system.
Evaluation unit (EU): a fragment of a marsh system that is considered a separate unit for the evaluation due to presence of any structure (e.g., roads, causeways, or other man made barriers) that fully bisects the marsh surface or marsh tidal channels.
Zone of influence: adjacent lands that are 500 feet away from the landward boundary of the salt marsh.
Output
Responses to questions that are used to describe ecological health of the zone of influence and evaluation unit(s); and tidal restrictions of the marsh system.
Estimated time to assess 1 acre site
Total 2-3 hours per evaluation unit (EU).
2-3 hours: Identify marsh formation type (step 1), divide salt marsh into EUs (step 2), measure ecological health of zone of influence (step 3), measure ecological health of salt marsh (step 4), and summarize/interpret results (step 5).
Comparison of habitat types
Can directly compare tidal wetlands within Narragansett Bay, RI.
Use as guide to design
NBM questions (variables) can be used as a guide to design for wetland restoration, but it contains properties that limit its application in the design of other planned wetlands. For example, the NBM does not provide validated threshold values for many variables. Users can refer to the variables and rationale in the main text to determine which conditions increase or decrease ecological health. Some can be translated into design criteria (e.g., avoid locating a created wetland in an area with high density residential development within the zone of influence).
Contact person
Andy Lipsky, Save the Bay, 434 Smith Street, Providence, RI 02908-3770
phone: (401) 272-3540; fax: (401) 273-7153; e-mail: habitat@savethebay.org(Andy)
Many variables can be used to identify ways to restore an unhealthy or a previously tidal wetland (e.g., remove or modify drainage control structures).
Related procedures
NBM and the ME Tidal Method (Bryan et al. 1997) are based on the Coastal Method (Cook et al. 1993), which in turn is based on the CT Method (Ammann et al. 1986) and the NH Method (Ammann et al. 1991). NBM differs from the Coastal Method in the following ways:
• NBM uses a list of questions to address each category. There is no procedure for combining responses to derive combined measures such as a functional index.
• NBM is adapted to Narragansett Bay tidal marshes.
• NBM does not include EU Analysis Graphs.
There is also a simplified version that Save the Bay staff use to identify potential restoration sites during brief site visits.
Extent of use/field testing
NBM has been applied to most, if not all, Narragansett Bay salt marshes. It has been continually used by Save the Bay staff and volunteers over the past two years. Restoration is underway at many of the evaluated marshes.
Proposed future revisions
NBM may be expanded to include riparian and freshwater wetlands within the next year.
Key Reference
Lipsky A. 1997. Narragansett Bay Method: A Manual for Salt Marsh Evaluation. Save the Bay, Providence, RI. 22 pp. ttachments.
Additional reference
Adamowicz, S. and A. Lipsky. 1997. Salt marsh restoration: a comprehensive bay-wide approach. Pages 41-43 In Conference Proceedings Vol. 1: Coastal Zone 97.