Primary purpose
To evaluate wetlands for community planning, education, and wetland inventory; but not for detailed impact analysis on individual wetlands.
Expertise needed
Individuals who have some knowledge of tidal marshes, but not necessarily wetland ecologists.
Applicable habitat types
Tidal marshes in New Hampshire.
Categories assessed
Ten functions are addressed: ecological integrity of the evaluation unit; ecological integrity of the zone of influence; shoreline anchoring; storm surge protection; wildlife, finfish, and shellfish habitat; water quality maintenance; recreation potential; aesthetic quality; education potential; and noteworthiness.
Procedure
The user(s) divides the tidal marsh system into evaluation units (EUs) based on observed tidal restrictions. Each EU is assessed separately by completing data sheets that (a) contain evaluation questions, (b) list evaluation criteria for each question, (c) assign a functional index (FI) (scale 0.1 to 1.0) to criteria for each question, and (d) includes a space for calculating the average functional index (AFI). Information for the entire marsh system is then summarized on EU Analysis Graphs.
Key Terminology
Average functional index (AFI): an index indicating the relative function of all tidal wetlands in an area (e.g., a town). AFI is calculated by averaging functional indices (1.0 = optimal function; 0.1 = low or no function).
Evaluation unit (EU): a fragment of a marsh system that is considered a separate unit for the evaluation due to a change in the natural hydrologic regime. Each time a tidal creek is crossed by a restriction in tidal flow (e.g., culvert, bridge, dike, or tide gate) a new EU is created.
EU analysis graphs: a set of 10 graphs that summarize the average AFIs within each EU and the entire marsh system.
Function: practical, measurable (either qualitatively or quantitatively) values of wetlands.
Functional index (FI): index assigned to each evaluation criteria (scale 0.1 - 1.0).
Output
Measure of function of an evaluation unit(s) and marsh system.
Estimated time to assess 1 acre site
8-24 hours: Determine study area (step 1), identify tidal marsh systems (step 2), identify marsh
category (step 3), determine type of marsh (step 4), determine number of evaluation units (EU) (step 5), and prepare marsh base map (step 6).
1 hour per EU: Conduct functional assessment (step 7).
4 hours per EU: Interpret results of functional assessment (step 8)
Comparison of habitat types
Can directly compare vegetated tidal wetlands within New Hampshire.
Use as guide to design
The Coastal method models should not be used as a guide to design; however, individual variables may provide useful information. It is not the intended purpose for the procedure; therefore, it contains properties that limit its application for this purpose. For example, the Coastal Method does not provide validated threshold values for many variables. Some of the variables may provide useful information. Users can refer to the variables to determine which conditions increase or decrease function. This can be translated into design criteria with explicit measurements (e.g., design a wetland with no distinct bank). Finally, the design criteria for some variables may be unsuitable and the overall rating of function may be misleading for the reasons given above.
Contact person
Richard Cook, Audubon Society of New Hampshire, 3 Silk Farm Road, Concord, NH 03301-8200
phone: (603) 224-9909; fax: (603) 227-0501; e-mail: r_cook@conknet.com
Related procedures
The Coastal Method is based on the CT Method (Ammann et al. 1986) and the NH Method (Ammann et al. 1991), but was adapted to New Hampshire vegetated tidal marshes. The Coastal Method differs from NH Method in the following ways:
Terminology: For example, the Coastal Method uses the term function rather than functional value.
The Coastal Method does not include a calculation of wetland value units (WVUs), i.e., the functional index is not multiplied by acreage to derive an alternate measure of function. Instead, the EU Analysis Graphs illustrate relative proportions of each EU function as it contributes to the overall marsh system.
The Coastal Method has been adapted for use in Maine; ME tidal Method (Bryan et al. 1997) and Rhode Island (NBM [Lipsky 1997]).
Extent of use/field testing
With respect to use, the Coastal Method has been applied primarily to community planning and restoration prioritization. The extent of use over the last two years is unknown.
Proposed future revisions
The Coastal Method is being reprinted with minor revisions and is scheduled to be available summer 1998.
Key Reference
Cook, R.A., A.J. Lindley Stone, and A.P. Ammann. 1993. Method for the Evaluation and Inventory of Vegetated Tidal Marshes in New Hampshire. Audubon Society of New Hampshire, Concord, NH. 77 pp. ppen.