Testing the use of best professional judgment to create biological benchmarks for habitat assessment of wetlands and oak savannas in northwestern Indiana

The Tolleston Strandplain at the southern end of Lake Michigan offers a unique “dune and swale” topography supporting oak savannas on the dunes and a mosaic of wetland communities in the swales. Following years of human degradation, sites in this area are now being restored. In this effort, assessments of vegetative quality have been necessary for proper management decisions. However, it is poorly understood what indices best reflect the vegetative quality of these oak savannas and wetlands. A potential method for determining the best indices for these community types is to use metric benchmarks that employ expert best professional judgment (BPJ). In order to confirm the viability and consistency of BPJ for creating benchmarks, Kappa analysis was used to determine the level of agreement among seven experts. They placed each of 63 transects from this unique landscape into one of four quality categories: (1) “good to very good,” (2) “medium,” (3) “poor,” and (4) “very poor.” While experts had good agreement about the quality of severely degraded riverine wetlands, they had fair agreement when assessing the swales, and poor agreement when assessing the oak savannas. Using discriminant analysis, follow-up questions, and a comparison of each expert's quality categories with remnant oak savanna metrics, varying perspectives of quality also were discovered which may have influenced the experts' assessments of the sites. Therefore, BPJ must be used with caution when creating metric benchmarks.