Date: 3/30/99

Time: 9:05

Type: Symposium

Number: 104

Responses of ground beetles to fire in original and reconstructed tallgrass prairies

*K.J. Larsen, Department of Biology, Luther College, Decorah , IA 52101
Contact e-mail: larsenkj@luther.edu

Ground beetle (Coleoptera: Carabidae) assemblages have been monitored at 4 tallgrass prairie sites in northeastern Iowa since 1994. The objective of this ongoing study is to identify "prairie restricted" species of ground beetles and quantify how these species are respond to the spring burning used to manage tallgrass prairies. Using pitfall traps, we have been comparing ground beetle assemblages in two original and two reconstructed tallgrass prairies with nearby non-prairie habitats. At each site, samples were taken from prairie plots 0, 1 and 2 years post-burn, as well as surrounding agricultural, old field, and/or wooded habitats. Compared with adjacent non-prairie habitats, tallgrass prairie contains the greatest abundance and species richness (n=88 species) of ground beetles. Thirty seven species may be "prairie restricted" as they were found only in tallgrass prairie and not in surrounding non-prairie habitats. The most abundant and probable prairie restricted species in NE Iowa include Oxypselaphus pusillus and Pterostichus commutabilis. Interestingly, the greatest number of carabid beetles and species were found in prairie immediately following fire, although overall ground beetle diversity as determined by the Hierarchical Richness Index was greatest several years post-burn. Additionally, some species, such as Chlaenius platyderus and O. pusillus, are "pyrophilic", most abundant immediately following a burn, while other species, such as Calathus gregarius and Pterostichus femoralis are "pyrophobic", and found in greater abundance several years after a fire. These results suggest that prairie managers need to utilize a diverse set of burn strategies, including not burning, to maximize ground beetle diversity in tallgrass prairies.

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