Science Services
Refinement of the Wisconsin Wetland Biological Index

This project represents the evaluation and expansion of a Wisconsin Wetland Biological Index based on plant and macroinvertebrate metrics

Six separate wetland biological communities, namely macroinvertebrates (primarily comprised of aquatic insects, snails, and other macro-crustaceans), microinvertebrates (i.e., zooplankton), diatoms (a type of algae found in all waters), amphibians (frogs and toads), small mammals (shrews, voles, and mice), and wetland plants, were evaluated as possible indices of wetland ecological integrity or health. Selected metrics of each community, except within the small mammal community (which probably failed because there were too few species to provide a useful index), were clearly related to a surrogate measure of human disturbance and a priori classification.

This report summarizes the methodology employed in monitoring each community and identifies the metrics (i.e., community attributes such as taxonomic richness that respond significantly to disturbance) incorporated into five biological indices. The performance of each index was evaluated by determining its ability to distinguish statistically significant differences among sub-sets of wetlands categorized a priori as to watershed land use type (e.g., agriculture versus urban versus natural land use), sub-classes (e.g., industrial versus residential urban lane use), agricultural intensity (3 categories based on percent agricultural development), and buffer width class (narrow versus wide cover in wetland perimeter), and a posteriori classification among five objective-based impact classes (impact based on chloride and total nutrient concentrations).

Each of the five biotic indices was largely successful in separating impacted wetlands from least-impacted reference wetlands. None of the indices was able to separate effects among the levels of agricultural intensity, and only the diatom index was able to separate between narrow and wide buffer classes.

A composite index incorporating the five biotic indices was developed to represent an Index of Ecological Integrity for Wisconsin long duration wetlands. While the Index of Ecological Integrity performs better than the component biotic indices, it is recommended that any of the five indices may be applied separately to evaluate the current condition of Wisconsin wetlands.

Continuing research and field application of the methods presented here are being implemented by the Wisconsin Department of Natural Resources.

For a detailed report of this research project please see the final report to US Environmental Protection Agency Region 5 [2.1 MB, .pdf file].

An overview of this study also is available from the U.S. Environmental Protection Agency.

For more information on this topic please contact:
Jen Hauxwell (608)221-6373