113 



the calculation is that habitat lost or replaced should be estimated on the basis of quality rather than 

 acreage. Thus, the technique can be applied to two areas for current comparison or to a before-and- 

 after setting to measure loss (as in habitat damage) or improvement (as in restoration projects). It is 

 limited by the fact that HSI models are not available for all species or areas, and often are based on 

 few variables and minimal data. r i.- u 



WET is a broader system used to estimate all wetland functions, using a rating of high, 

 moderate or low, and including functions such as hydrology, water purification, food production and 

 export fish and wildlife habitat, and values such as esthetic, historic and passive recreation (Adarnus 

 et al. 1987). A major advantage is that of a landscape approach which considers topography, wetland 

 ctinnectivity, and other geomorphic parameters. Although WET uses waterfowj and waders as 

 biological indicators, groups rather than species are assessed, and habitat associations are not very 

 specific. Moreover, rare species are immediate "red flags" that outweigh other considerations. 



Partly a an outgrowth of attempting to broaden HEP to assemblages or communities rather than 

 species. Short & Burnham (1982) devised a guild analysis using a resource matrix for bird species. As 

 a community or habitat-oriented approach, GMA allows assessment at various scales, and attempts to 

 as.sess habitat resource availability in relation to behavioral characteristics of the guilds that limit them 

 to certain habitats. 'l"he overall advantage is that it deals with large- and mid-scale issues using simple 

 measures like presence and absence, meaning that general information can be used when detailed data 

 are not available. Additionally, the scale can be modified to more detailed habitat units or by species 

 selection, but the focus remains on availability of habitat resources such as food, nest-sites, rest areas, 

 etc. for a guild of species rather than on detailed knowledge of a single species or taxonomic group. 



Any of these systems can be used to compare two or more wetlands, to compare a single 

 wetland before and after impact or enhancement (as in mitigation banking), or to assess quality of a 

 replacement wetland Greater precision is required to measure enhancements than to measure 

 restoration success (because they tend to improve nab itat less dramatically than those actions that start 

 from near-zero), which itself is more demanding tlian measuring the success of wetland creation 

 Hence, different goals demand different levels of precision. 



References 



Adarnus, P. R., E. J. Clairain, Jr., R. D. Smith, and R. E. Young. 1987. Wetland Evaluation 

 Technique (WET); Volume II: Methodology. Operational Draft Tech. Rep. Y-87. 

 U.S. Army Corps of Engineers, Waterways Experiment Stat., Vicksburg, MS. 



FlCKid, B. S , M. E. Sangster, R D. Sparrowe, and T. S. Baskett. 1977. A handbook for 

 habitat evaluation procedures. U.S. Depi. Im. Fish Wildl. Serv., Resour. Publ. 132. 

 77 p. 



Short H. L. and K. P. Burnham. 1982. Technique for structuring wildlife guilds to evaluate 

 impacts on wildlife awmunities. U. S. Fish and Wildl. Serv. Spec. Sci. Rpt. (Wildl.) 

 No. 22. 34 pp. 



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