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PRELIMINARY INVENTORY OF EPIGEIC ANTS AT THE TEWKSBURY UNIT OF THE ST. CROIX NATIONAL SCENIC RIVERWAY

PRELIMINARY INVENTORY OF EPIGEIC ANTS AT THE TEWKSBURY UNIT OF THE ST. CROIX NATIONAL SCENIC RIVERWAY

Chelsie Harder,Department of Biology, University of Wisconsin—River Falls
John Wheeler, Department of Biology, University of Wisconsin—River Falls

We sampled epigeic arthropods (insects, spiders, millipedes, etc.) with pitfall traps at the NPS Tewksbury Unit during June 2007. The Tewksbury Unit is a narrow strip of remnant prairie located south of Osceola on the Wisconsin side of the St. Croix River. Future prescribed burns are planned at this site. As an initial stage in the analysis, we chose to focus on ants; specimen identifications of other taxa are ongoing. Ants are widely recognized as a good indicator group for programs that seek to monitor environmental change (Kaspari and Majer 2000). We trapped at three sites within the unit. At each site, 29 traps were installed in a nested-cross array (Perner and Schueler 2004); this technique should allow us to calculate absolute density for common species so that we can monitor quantitative as well as qualitative trends in the future. Identification of ant species is in progress; however, we have tentatively detected over 20 morphospecies in the samples. To date, we have sorted 1674 individual ants. Some species are very common while others are quite rare.

Suggested Reading

Kaspari, M, and J. D. Majer. 2000. Using ants to monitor environmental change. Chapter 7 in Ants: Standard Methods for Measuring and Monitoring Biodiversity. 2000. Edited by D. Agosti, J. D. Majer, L.E.Alonso, and T. R. Schultz. Smithsonian Institution Press.

Perner, Jorg and Silvio Schueler. Estimating the density of ground-dwelling arthropods with pitfall traps using a nested-cross array. 2004. Journal of Animal Ecology. 73, 469-477.