Bee Species Inventory of Oak Savanna Habitats in Indiana Dunes National Lakeshore

Jean, Robert

Brief Description: An inventory of the bee species present in oak savanna habitats at Indiana Dunes National Lakeshore. Full Description: Oak savanna is a highly threatened habitat type in the Midwest. Potential savanna conservation areas often require habitat restoration to overcome the effects of long-term fire suppression and to reverse landscape changes brought on by past land uses such as farming and sandmining. However, we lack knowledge of how changes brought on by restoration will affect plant and animal populations. To improve our understanding of how these changes influence savanna communities, work at Indiana Dunes National Lakeshore is examining the effects of savanna structure on several animal and plant communities. The current project examines how woody vegetation structure and plant diversity in savannas affect pollinator communities, especially communities of solitary bees. Bee specimens were collected in the initial year (2003) by pan trapping. Pan trapping is a passive sampling technique that uses colored bowls and detergent water to attract bees as well as other insect types. The second year of sampling used pan trapping (for part of the year) and netting at flowers. Netting at flowers is an active sampling technique and is an important addition to pan trapping. These techniques were performed at 25 historic savanna sites (17 at Indiana Dunes, 1 at Hoosier Prairie, and 7 at Tefft Savanna/Jasper-Pulaski FGA). Today these sites are forests, savannas, woodlands, and old fields, as a result of fire suppression, frequent fire, agriculture, sand mining, and residential development. Birds, butterflies, amphibians, reptiles, and plants have been previously surveyed at these sites and extensive habitat mapping and habitat structural analyses have been performed, as well as fire histories have been documented since 1982 at these sites. Study groups have been selected, in part, to represent a mix of dispersal abilities and a mix of ecosystem functions and responsiveness to different habitat elements. Bees are a diverse taxon that may respond strongly to herbaceous vegetation.Bees are an important addition to these groups because knowledge of the bee communities at these sites may help in conservation and management efforts at these sites. Knowing the occurrence and abundance of bee species helps us understand the potential pollinator base of a site. In addition the netting records help us determine what bee species are visiting particular flower species. Knowledge of the pollinators of a particular plant species and potential pollinators in the area may help in conservation efforts of rare plant species or those that are only found in savanna habitats. Furthermore, savanna habitats are historically rich in forb species and thus knowledge of the pollinators of these forbs, which are mainly bees, is essential to understanding whether these forbs are reproductively limited by pollination.Lists of insect organisms for entire habitats are rare. The collections of bees from the savannas of northern Indiana are an important addition. So far 1389 bees have been identified. Additional bees have also been collected and identifications of these specimens are ongoing. Currently the bees in these savannas are represented by 72 species in 22 genera and 5 families (see Microsoft Access database). This list of bees will not only be important in conservation and management decisions for oak savannas, but will also help address important questions such as: a) How do habitat disturbances and habitat structure affect bee communities?, b) How does fire affect bee species composition? This list of bees will also be an important comparison with other studies of bees in oak savannas as well as with studies of bees in other habitats.

Bee Species Inventory of Oak Savanna Habitats in Indiana Dunes National Lakeshore

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