Primary purpose
To assess baseline fish and wildlife habitat conditions, determine the direct impacts of project construction on these conditions, and develop a mitigation plan to offset these impacts.
Expertise needed
Team with designated voting members from each of the following: US Fish and Wildlife Service, Pennsylvania Fish Commission, Pennsylvania Game Commission, and applicant/action agency. These individuals must have training and experience in the basic principles of fisheries and/or wildlife biology and be certified in HEP.
Applicable habitat types
Most terrestrial, wetland, and aquatic habitats in Pennsylvania.
Category assessed
Habitat suitability of selected fish, wildlife, or invertebrates.
Procedure
The users select a few evaluation species that could potentially use cover types within the study area and review the available habitat suitability index models. Existing PAM HEP models are selected, otherwise HEP models are used and/or simplified. Models may also be developed by the team performing the evaluation. The models (a) identify the individual model variables, (b) list direct or indirect measures of model variables, (c) assign a suitability index (scale 0-1.0) to conditions for each variable, and (d) include the equation for calculating the habitat suitability index (HSI). The users visit the study area (or reviews plans for predicted future conditions) to measure the habitat features listed in the models. The HSIs and habitat units (HUs) are calculated. If there is a need to document value judgments, the relative value index (RVI) may be calculated.
Key Terminology
Average annual habitat unit (AAHU): the total number of HUs gained or lost as a result of a proposed action.
Compartment: an area on a map with a designated landuse or wetland classification, and separated from areas with the same or different classifications.
Evaluation species: individual animal species, groups of species, life stages of a species, or life requisites of a species selected for purposes of analysis.
Habitat suitability index: 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 an evaluation species by the size of the areas for which the HSI was calculated (HU = HSI x size of habitat).
Relative value index (RVI): a value between 0.0 to 1.0 that is used to adjust habitat unit data to accommodate socioeconomic and environmental considerations.
Output
Measures of habitat suitability of each cover type and the entire project area for each evaluation species. The PAM HEP model HSI measures habitat suitability of a compartment relative to optimum habitat suitability for a species in Pennsylvania.
Estimated time to assess 1 acre site
Total 16 hours.
8 hours: Define study limits (step 1) and select evaluation species (step 2).
8 hours per cover type: Determine baseline habitat units (step 3).
Comparison of habitat types
Can directly compare habitats within Pennsylvania.
Contact person
Hugh Palmer, Pennsylvania Game Commission, P.O. Box 292, Millville, PA 17846 phone: (717) 458-6320; fax: none; e-mail: none
Use as guide to design
The PAM HEP models may be used as a guide to design. Users can refer to the model variables to determine which conditions increase or decrease habitat suitability. Habitat suitability for the mallard is increased when the wetland is designed to have > 20% emergent vegetation in the littoral zone (variable V3). Each variable provides information on conditions that should be avoided. For example, to be suitable for mallards, there must be > 10% herbaceous canopy cover greater than 18 in. in height (variable V1). Finally, the information in the PAM HEP models is useful because it provides design criteria with explicit measurements (e.g., > 30% herbaceous canopy cover > 18 in.).
Related procedures
PAM HEP is based on HEP (USFWS 1980), but modified to reduce application and analytical time by 50% - 75%. PAM HEP differs in the following ways:
• Project impacts and mitigation plan effectiveness are determined by comparing habitat units among a series of target years, as in HEP; however PAM HEP uses only three target years. These are the Target Year Baseline (TYB), Target year Construction (TYC), and Target Year Mitigation (TYM).
• When the models are applied, variable conditions are determined for the entirety of cover type compartments. Three to five compartments are sampled for each habitat type. In contrast, HEP applies the models to point sample sites.
• The Relative Value Index (RVI) analysis is conducted only when selecting alternatives or when full mitigation is not feasible. Also, the RVI in PAM HEP indicates the relative value of land use/cover types, whereas it refers to the relative value of evaluation species in HEP.
WHAMS (Palmer et al. 1993) is based on PAM HEP, but is designed specifically for use in developing wildlife management plans.
Extent of use/field testing
PAM HEP has been used on a variety of projects (e.g., small wetlands replacement, federal highway and flood-control projects). Extent of use over the last two years is unknown; however, during the mid 1980’s PAM HEP constituted approximately 1/3 of the HEP applications.
Proposed future revisions
Yes, there are plans but the resources have not been allocated. Proposed changes would be in the form of WHAMS (Palmer et al. 1993), e.g., eliminate Relative Value Index.
Key References
Palmer, J.H., M.T. Chezik, R.D. Heaslip, G.A. Rogalsky, D.J. Putman, R.W. McCoy, and J.A. Arway. 1985. Pennsylvania Modified 1980 Habitat Evaluation Procedure Instruction Manual. U.S. Fish and Wildlife Service, State College, PA.
Palmer, J.H. 1995. Wildlife Assessment and Management PAM HEP Habitat Suitability Index Model Manual. Pennsylvania Game Commission, Bureau of Land Management, Harrisburg, PA.
U.S. Fish and Wildlife Service. 1980. Habitat Evaluation Procedure (HEP) Manual (102 ESM). U.S. Fish and Wildlife Service, Washington, DC.