Primary purpose
To evaluate wetlands for community planning, identifying restoration opportunities, education, and wetland inventory; but not for detailed impact analysis on individual wetlands.
Expertise needed
Individuals who have some knowledge of tidal marshes (e.g., conservation commission, planning boards, or interested individuals), but not necessarily wetland ecologists.
Applicable habitat types
Vegetated tidal marshes in Maine.
Categories assessed
Seven functions, values, and ecological integrity categories are addressed: ecological integrity of the marsh system; ecological integrity of the zone of influence; wildlife, finfish, and shellfish habitat; recreational and commercial potential; aesthetic quality; educational potential; and noteworthiness.
Procedure
Separate forms are included for each of seven assessments 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) for the assessment. For the ecological integrity assessment, the user(s) divides the tidal marsh system into evaluation units (EUs) based on observed tidal restrictions. Results are then combined to estimate the ecological integrity of the marsh system. For other functions and values, the entire marsh system is assessed as a single unit by completing similar data sheets.
Key Terminology
Average functional index (AFI): an index indicating the relative health, productivity, or value of the marsh system; it can be used to identify marshes in a town that can most benefit from restoration or protection. AFI is calculated by averaging functional indices (1.0 = optimal function; 0.1 = low or no function).
Ecological integrity: the natural (undisturbed) quality of an ecosystem.
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.
Functional index (FI): index assigned to each evaluation criteria (scale 0.1 - 1.0).
Output
Provides an indication of ecological integrity of evaluation unit(s); and ecological integrity, function, and value of the marsh system.
Estimated time to assess 1 acre site
Total 12-28 hours per marsh system.
8-24 hours: Select study area (step 1), identify tidal marsh systems (step 2), prepare marsh system base maps (step 3), determine number of evaluation units (EU)(step 4), and evaluate ecological integrity, functions, and values (step 5).
4 hours per EU: Interpret results (step 6).
Comparison of habitat types
Can directly compare vegetated tidal wetlands within Maine.
Use as guide to design
The ME Tidal Method models should not be used as a guide to design for wetland sites or evaluation units. It is not the intended purpose for the procedure; therefore, it contains properties that limit its application for this purpose. For example, the ME Tidal Method does not provide validated threshold values for many variables. Some variables may provide useful information. Users can refer to the variables to determine which conditions increase or decrease ecological integrity. This can be translated into design criteria (e.g., design a wetland with no ditches). The ME Tidal Method was developed primarily for application to marsh systems; thus it provides information that may be useful with regard to the restoration of entire marsh systems or portions of systems affected by tidal restrictions.
Contact person
Robert Bryan, Maine Audubon Society, Gilsland Farm, P.O. Box 6009, 118 U.S. Route One, Falmouth, ME 04105 phone: (207) 781-6180 ext. 235; fax: (207) 781-0974; e-mail: none
Related procedures
The ME Tidal Method and the NBM (Lipsky 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). The ME Tidal Method differs the Coastal Method in the following ways:
• Adapted to Maine vegetated tidal marshes and state shoreland zoning criteria.
• The ME Tidal Method models are applied to the entire marsh system (except for "Ecological Integrity of Evaluation Units), whereas the Coastal Method models are applied to each evaluation unit.
• Does not include EU Analysis Graphs.
Extent of use/field testing
The ME Tidal Method has been used for conservation planning by local communities and non-governmental organizations (NGOs). It has been used on two projects during the last two years, one of which included over 20 tidal marshes within a major tidal estuary system.
Proposed future revisions
None.
Key Reference
Bryan, R.R., M. Dionne, R. Cook, J. Jones, and A. Goodspeed. 1997. Maine Citizens Guide to Evaluating, Restoring, and Managing Tidal Marshes. Maine Audubon Society, Falmouth, ME. 87 pp. ppen.