Primary purpose
To quantify changes in habitat quality and quantity that are projected to occur as a result of proposed wetland enhancement projects. Developed specifically to evaluate proposals submitted for funding under the Coastal Wetlands Planning, Protection, and Restoration Act (CWPPRA).
Expertise needed
Professional(s) who have training and experience in the basic principles of coastal wetlands and coastal fish and wildlife habitat.
Applicable habitat types
Coastal Louisiana wetland types: fresh/intermediate marsh, brackish marsh, saline marsh, bottomland hardwoods, and fresh swamp.
Category assessed
Habitat suitability.
Procedure
The user(s) classifies the wetland community and visits the study area (or reviews plans for predicted future conditions) to measure the habitat features listed in the appropriate community model. The community models (a) identify the individual model variables, (b) assign a suitability index (scale 0-1.0) to conditions for each variable, and (c) include the equation for calculating the habitat suitability index (HSI). The HSIs, habitat units (HUs), and average annual habitat units (AAHUs) are calculated.
Key Terminology
Average annual habitat unit (AAHU): the total number of HUs gained or lost as a result of a proposed action, divided by the life of the action.
Habitat suitability index (HSI): unitless number bounded by 0 and 1 where 0 represents no habitat and 1 represents optimum habitat.
Habitat unit (HU): a value derived from multiplying the HSI for a particular area by the size of the area for which the HSI was calculated (HU = HSI x size of habitat).
Output
Habitat suitability of a community wetland type.
Estimated time to assess 1 acre site
Total 1 hour per site.
Time variable: Pre-assessment activities (step 1)
1 hour: Assessment (step 1) and record results (step 2).
Comparison of habitat types
Can directly compare areas within the same wetland type (e.g., brackish marsh). Wetlands from different wetland types (e.g., brackish and saline marshes) are compared when ranking coastal restoration projects. Comparisons are made in terms of AAHUs and $/AAHU for all projects, regardless of wetland type. For regulatory projects, comparisions are only made within wetland types because compensation for impacts usually must be made with the same wetland type as the impacted area.
Use as guide to design
WVA may be used as a guide to design. Users can refer to the variables to determine which conditions increase or decrease habitat suitability. Habitat suitability in the saline marsh is increased when it is designed to have access to aquatic organisms (variable V6). Some variables provide information on conditions that should be avoided. For example, to be suitable saline marsh habitat, the wetland should have low percent cover of emergent vegetation (variable V1). Finally, the information in the WVA models is useful because it provide explicit design criteria (e.g. average annual salininy 9 - 21 ppt).
Contact person
Kevin J. Roy, U.S. Fish and Wildlife Service, 825 Kaliste Saloom, Building II, Suite 102, Lafayette, LA 70508 phone: (318) 262-6662 ext. 226; fax: (318) 262-6663; e-mail: r4fwe_lala@fws.gov
Related procedures
WVA is based on HEP (1980), but modified to reduce application and analytical time. WVA differs in the following ways:
• WVA is a community approach, whereas HEP is a species-oriented approach.
• WVA has been developed for use in Louisiana coastal wetlands.
Extent of use/testing
The WVA models have been revised several times since they were developed in 1991. WVA has been used to evaluate 50-60 projects CWPPRA coastal restoration projects over the last two years. WVA has also been used to evaluate proposed impacts for approximately 200 permit applications and 30-40 mitigation areas.
Proposed future revisions
Anticipated, but no planned schedule.
Key References
Environmental Work Group. 1998. Wetland Value Assessment Methodology and Community Models. Environmental Work Group, Coastal Wetland Planning, Protection, and Restoration Act (CWPPRA). 13 pp. + appen.
Louisiana Department of Natural Resources. 1994. Habitat Assessment Models for Fresh Swamp and Bottomland Hardwoods within the Louisiana Coastal Zone. Louisiana Dept. of Natural Resources, Baton Rouge, LA. 10 pp. + appen.