Primary purpose
To provide a procedure for assessing functional capacity of wetlands in the glaciated northeast and midwest. It also serves as a template and provides a step by step process for developing rapid assessment procedures for various regions of the continental United States.
Expertise needed
Two person team of experienced wetland scientists, one with a soils/hydrology background and the other competent in plant identification and ecology.
Applicable habitat types
Depressional, slope, lacustrine fringe, extensive peatland, flat and riverine HGM class wetlands in the glaciated northeast and midwest. The procedure template is applicable to all wetland types in the continental United States; however, assessment models have not been developed for any other regions
Categories assessed
Approximately eight wetland functions, the list of which depends upon the wetland regional class. The glaciated northeast/midwest models include eight functions: modification of ground water discharge; modification of ground water recharge; storm and flood water storage; modification of stream flow; modification of water quality; export of detritus; contribution to abundance and diversity of wetland vegetation; and contribution to abundance and diversity of wetland fauna.
Procedure
The Rapid Assessment Procedure consists of two components: development and the glaciated northeast/midwest models. Development of a procedure for a particular wetland class and region requires several steps. The glaciated northeast/midwest models, which are an example of a completed procedure, contains an inventory sheet and models. The user(s) distinguishes the wetland assessment areas (WAAs) based on hydrogeomorphic wetland class (Brinson 1993) and physical separation criteria. The user then visits the wetland assessment area and completes the inventory sheet by selecting conditions that best describe various landscape, hydrologic, soils, vegetation variables. Vegetation types/species and pre-emptive status are also identified. Information from the inventory sheet is applied to the models which (a) contain variables, (b) list conditions for each variable, (c) assign a weight (scale 0-3) to conditions for each variable, and (d) provide space for calculating the functional capacity index (FCI). Functional Capacity Units (FCUs) may also be calculated.
Key Terminology
Direct indicators of function: variables which by themselves provide strong evidence that the potential functional capacity is high, obviating the need to further evaluate the wetland. For example, evidence of sedimentation is a direct indicator that potential functional capacity is high for "moderation of water quality".
Functional capacity index (FCI): an index generated for each function, which indicates the potential degree (capacity) to which the wetland performs the function.
Functional Capacity Units (FCUs): measure of functional capacity incorporating the size of the wetland (FCU = FCI x size of wetland assessment area).
Indicators of disfunction: variables that obviate the need to further evaluate the wetland for a function. For example, the absence of an outlet indicates that the wetland is not performing the storm and flood-water storage function.
Pre-emptive status: designations that identify the wetland assessment area as important (e.g., public ownership, documented habitat for state or federal listed species, regionally scarce wetland category).
Primary variables: variables used in the models which are capable of influencing function independently and are assumed to be of equivalent value relative to degree of influence.
Secondary variables: variables with less direct influence which are not used in the models, but have been included to allow flexibility and provide options for future model building in other regions or at the subregional level.
Variables: functional indicators identified for each of the functions.
Variable conditions: the range of conditions under which the variables occur.
Contact Persons
Dennis Magee, Normandeau Associates, 25 Nashua Road, Bedford, NH 03102 phone: (603) 472-5191; fax: (603)472-7052; e-mail: nai@nh.ultranet.com
Garrett Hollands, ENSR, 155 Otis Street, 6 Maple St., Northborough, MA 01532 phone: (508) 393-8558; fax: (508) 393-5104; e-mail: ghollands@ensr.com
Output
Measure of functional capacity of a site relative to the range of possible scores for a given model.
Estimated time to assess 1 acre site
Total 1-2 hours per WAA (if models are available)
1-2 hours: Prepare for assessment (step 1), conduct assessment (step 2), and summarize results (step 3).
Total 121-162 hours (if models must be developed)
120-160 hours [several weeks of work]: Development phase (prior to steps 1-3).
1-2 hours per WAA: Prepare for assessment (step 1), conduct assessment (step 2), and summarize results (step 3).
Comparison of habitat types
Can directly compare wetlands within the same regional class as defined by the models (depressional wetlands in the glaciated northeast/midwest). Cannot directly compare wetlands from different classes (e.g., depressional wetland and riverine wetland within same region) or different regions. However, results from assessing different regional classes can be used to aid in decisions.
Use as guide to design
The Rapid Assessment Procedure glaciated northeast/midwest models can be used as a guide to design. Users can refer to the model variables to determine which conditions increase or decrease functional capacity. Functional capacity for the "modification of water quality" function is increased when the wetland is designed to have restricted outflow. Each variable provides information on conditions that should be avoided. For example, to have the capacity to modify water quality, the outlet should not be perennial. Most of the information in the models is useful because it provides explicit design criteria (e.g., design wetland with a histosol or clayey soil) or general guidance (e.g. high fluctuation of surface water level is a preferred condition for the modification of ground water recharge function).
Related procedures
The Rapid Assessment Procedure is an improved version of Hollands and Magee (1985) and it incorporates some concepts and terminology from the HGM Approach (Smith et al. 1995). The Rapid Assessment Procedure differs from the HGM Approach in the following ways:
• Terminology and definition of terms differ.
• Models and variables are not scaled to a reference standard, but are based on the literature and best professional judgment of the regional experts. Reference wetland data can be incorporated in the models when the data becomes available.
• Current models only use HGM classes, not subclasses.
The MDE Method (Furgo East 1995) is similar to and incorporates many aspects of the Rapid Assessment Procedure.
Extent of use/field testing
The glaciated northeast/midwest models of the Rapid Assessment Procedure are based on professional experience of the regional experts and data from several thousand wetlands assessed throughout the region. Reference data were used to establish wetland processes and functions, and to identify the variables and range of variable conditions. This procedure was published in April 1998, and thus far has been used only in New York on several small routine regulatory projects. The procedure was field tested at various stages during its development. It is also the basis for a similar procedure, the MDE Method (Furgo East, Inc. 1995) which was developed for, and used in Maryland.
Proposed future revisions
Not at this time.
Key Reference
Magee, D.W. 1998. A Rapid Procedure for Assessing Wetland Functional Capacity. Normandeau Associates, Bedford, NH. (Available from the Association of State Wetland Managers, Berne, NY). 190 pages.
Additional reference
Brinson, M.M. 1993. A Hydrogeomorphic Classification for Wetlands. Wetlands Research Program Technical Report WRP-DE-4. US Army Corps of Engineers, Waterways Experiment Station, Vicksburg, MS. 79 pp. + appen.