Insects as Indicators of Habitat Quality, Ecological Integrity and Restoration Success in Illinois Prairies, Savannas and Woodlands

Abstract

The typical methods that ecologists use for assessing habitat quality involves calculating quality based on primarily floristic data. This is true of evaluation of habitats in Illinois – although new methods have become available for assessing habitats based on other taxa. These alternative methods are often not in widespread use, especially in Illinois, and consist of using invertebrate indicator taxa to assess the ecological integrity of prairies, savannas, and woodlands (aquatic invertebrate survey tend to be more commonly used). There is a large diversity of invertebrates for which we have information on the life history, seasonality, and diet that live in these unique habitats. Critically, these organisms are often sensitive to environmental change and habitat fragmentation. Insects in particular can thus be valuable indicators of habitat quality and ecosystem integrity. For this study, we chose to look at four groups of insects as indicators, based on their life history, ease of identification, and knowledge of the co-authors. These groups are well represented in grassland biomes and include: (1) grasshoppers (Orthoptera: Acridoidea); (2) butterflies (Lepidoptera: Rhopalocera); (3) cicadas (Hemiptera: Cicadoidea); and (4) tiger beetles (Coleoptera: Carabidae). By looking at both the abundance and species diversity at a given site for each of these groups, we hoped to develop tools that would allow land managers to utilize these taxa as indicators of high quality prairie. This is not an entirely novel pursuit, grasshoppers and butterflies have consistently been shown to represent other invertebrate and plant taxa effectively in grasslands worldwide. Through this study we have developed a butterfly quality index tool for assessing sites. The taxa examined by our group also often rely on habitat quality that cannot be assessed by floristic data alone, for this we have gathered data on habitat heterogeneity.Illinois Department of Natural Resources, State Wildlife Grant Project Number T-92-R-1unpublishednot peer reviewedOpe