Primary purpose
To assess wetland functions in planning situations. (Use not recommended for regulatory or management purposes).
Expertise needed
Professionals who have schooling in environmental sciences. A trained hydrogeologist is required to perform higher level assessments on groundwater potential.
Applicable habitat types
Freshwater non-tidal wetlands in Massachusetts. Wildlife and visual-cultural submodels also applicable to the northeast US.
Categories assessed
Three resource factors are addressed: wildlife value (Golet submodel); groundwater potential (Heeley-Motts submodel); and visual-cultural value (Smardon-Fabos submodel).
Procedure
The evaluation involves a three level system of elimination. Level I consists of a list of criteria (e.g., endangered species) to identify whether the wetlands merit preservation even without assessment of individual functions. Those wetlands that are not outstanding are evaluated at Level II. For the Golet wildlife model, the user visits a wetland area and rates the wetland using a table that (a) identifies ten criteria, (b) assigns a significance coefficient (scale 1-5) to each criterion, (c) lists specifications for each criterion, and (d) assigns a rank (scale 1-3) to each specification. Ranks are multiplied by significance coefficients for each criterion; subscores are summed to obtain a wildlife score. A similar scoring approach is used in the Smardon-Fabos visual-cultural model. The Heeley-Motts groundwater potential submodel provides a table with six wetland types classified by geological characteristics of underlying deposits and their potential rating for water production. The groundwater potential submodel also outlines steps for general reconnaissance, phase 2 field study, and phase 3 final study. Level III takes the Level II output and suggests economic values for each function.
Key Terminology
Resource factor: factor evaluated by sub-models (i.e., wildlife, visual-cultural amenities, and groundwater).
Sub-model: model that provides the means for ranking wetlands for one resource factor.
Factor score: score resulting from the application of a sub-model (i.e., wildlife score, visual-cultural score, and groundwater potential score).
Output
Measures of resource factor value (capacity to perform the function) and economic value of a site.
Estimated time to assess 1 acre site
Total 9-18 hours per site.
8-16 hours: Classify wetlands, review list of 11 criteria, and mark outstanding wetlands (Level 1)
1-2 hours: Evaluation of Relative Values.
Comparison of habitat types
Can directly compare freshwater wetlands within Massachusetts and other areas in the glaciated northeast.
Use as guide to design
The Larson Method wildlife model should not be used as a guide to design; however, individual variables (criteria) may provide useful information. It is not the intended purpose for the procedure; therefore, it contains properties that may limit its application for this purpose. For example, the wildlife model does not provide validated threshold values for many variables. Some of the variables may provide useful information. Users can refer to the elements to determine which conditions increase or decrease function. This can be translated into design criteria with explicit measurements (e.g., design with five or more classes). Finally, the design criteria for some variables may be unsuitable and the overall rating of function may be misleading for the reasons given above. The visual-cultural model may be used as a guide to design; however, further review would be needed to make a final determination. The groundwater model potential model should not be used as a guide to design unless sufficient data have been collected (e.g., at least a phase 2 field analysis is completed).
Contact persons
Joseph Larson, Environmental Institute, University of Massachusetts, Amherst, MA 01003-0820
phone: (413) 545-2842; fax: (413) 545-2304; e-mail: larson@tei.umass.edu
Frank Golet, Dept. of Natural Resources Science, Woodward Hall, Univ. of Rhode Island, Kingston, RI 02881 phone: (401) 874-2916; fax: (401) 874-4561; e-mail: "none"
Related procedures
The original wildlife submodel (Golet 1976) was modified several times (see: Golet 1979, Golet and Davis 1982, and Wencek 1986). Between 1993 and 1996, some of the criteria from the wildlife submodel were incorporated or modified for use in a GIS-based assessment method. This method was applied to the Pawcatuck River watershed and later to the entire state of Rhode Island.
Extent of use/field testing
The Larson Method has been used in revised form for a variety of projects including: local (municipal), county, and statewide inventories and planning; state regulatory decision-making (RI, 1974-1994); impact assessment; and open space acquisition. The state of Rhode Island discontinued use of the wildlife submodel of the Larson Method in 1994. Its use for regulatory decision-making is no longer advocated due to faulty assumptions and lack of justification for comparisons among wetlands (Pers. comm.: Frank Golet, University of Rhode Island, June 9, 1998).
Proposed future revisions
None.
Key References
Larson, J.S. (ed). 1976. Models for Assessment of Freshwater Wetlands. Publication No. 32, Water Resources Research Center, University of Massachusetts, Amherst, MA.
Golet, F.C. 1976. Wildlife wetland evaluation model. Pages 13-34 In Larson, J.S. (ed). Models for Assessment of Freshwater Wetlands. Publication No. 32, Water Resources Research Center, University of Massachusetts, Amherst, MA.
Heeley, R.W. and W.S. Motts. 1976. A model for the evaluation of ground-water resources associated with wetlands. Pages 52-65 In Larson, J.S. (ed). Models for Assessment of Freshwater Wetlands. Publication No. 32, Water Resources Research Center, University of Massachusetts, Amherst, MA.
Smardon, R.C. and J.G. Fabos. 1976. Visual-cultural sub-model. Pages 35-51 In Larson, J.S. (ed). Models for Assessment of Freshwater Wetlands. Publication No. 32, Water Resources Research Center, University of Massachusetts, Amherst, MA.
Golet, F.C., and J.S. Larson. 1974. Classification of Freshwater Wetlands in the Glaciated Northeast. Resource Publication 116, U.S. Fish and Wildlife Service, Washington, D.C. 56 pp.
Additional References
Golet, F.C. 1979. Rating the wildlife value of northeastern freshwater wetlands. Pages 63-73 In Greeson, P.E., J.R. Clark, and J.E. Clark (eds). Wetland Functions and Values: The State of Our Understanding. Proceedings, National Symposium on Wetlands, American Water Resources Association. Minneapolis, MN.
Golet, F.C., and A.F. Davis. 1982. Inventory and habitat evaluation of the wetlands of Richmond, Rhode Island. Occasional Papers in Environmental Science No. 1. College of Resource Development, University of Rhode Island, Kingston. 48 pp.
Wencek, M.D. 1986. Application of the Golet system in assessing wildlife and habitat functions in Rhode Island. Pages 239-243 In Kusler, J.A., and P. Riexinger (eds). Proceedings of the National Wetland Assessment Symposium. Technical Report 1. Association of State Wetland Managers, Berne, NY.