Odonata Richness and Abundance in Relation to Vegetation Structure in Restored and Native Wetlands of the Prairie Pothole Region, USA

Over the past couple of decades, 2,200,000 ha of wetlands and grasslands have been restored in the prairie pothole region, USA. However, many restored and remnant wetlands in the region are dominated by two invasive plant species, reed canary grass (Phalaris arundinacea) and cattail (Typha spp.), which form dense monotypic stands. These restorations are usually evaluated as habitat for waterfowl and other birds; however, there is a need to evaluate their success for invertebrates. Odonata (dragonflies and damselflies) are ideal organisms to include in our evaluations of restored wetland habitat quality for both ecological and practical reasons. To examine the association between vegetation structure and odonate assemblages in shoreline vegetation of prairie pothole wetlands, we compared odonate richness and abundance in dense, monotypic stands to that of vegetation with diverse vertical structure. We also observed the use of these two different habitats by odonate species classified as "of conservation concern" in Iowa. Odonate species richness was substantially greater in the mixed-structure vegetation than in monotypic stands. A similar trend was found in odonate species with a "vulnerable" or "uncommon" conservation status. The number of occurrences of species of conservation concern was four times greater in mixed than in monotypic vegetation. A comparison of our data to those collected in the 1990s for one monotypic vegetation site further supported this conclusion. Many odonate species are targets for conservation and can readily benefit from wetland restoration and reconstruction if the sites are managed for proper vegetation structure.