PRE-BURN BASELINE INVENTORY OF EPIGEIC INVERTEBRATES AT THE TEWKSBURY UNIT OF THE ST. CROIX NATIONAL SCENIC RIVERWAY

John Wheeler, Department of Biology, University of Wisconsin - River Falls
Chelsie Harder, Cedar Creek Ecosystem Science Reserve, East Bethel, Minnesota
Steven Wagner, Department of Biology, University of Wisconsin - River Falls

Mid-June and mid-August pre-burn samples of epigeic (surface ground-dwelling) invertebrates were taken using pitfall traps at the NPS Tewksbury Unit during June 2007. The Tewksbury Unit is a narrow strip of remnant prairie, woods, and savanna located near Osceola, WI on the flat surface of a sandstone bluff, adjacent to but about 120 vertical feet above the St. Croix River. We sampled at three sites within the unit. At each site, 29 traps were installed in a nested-cross array (Perner and Schueler 2004), a technique devised to allow calculation of absolute density for common species. We will provide an update of the ant subproject (reported last year). Data and population density estimates for selected adult carabid beetle, millipede, and spider species will be presented and compared for both mid-June and mid-August samples. We will also discuss the prevalence of an interesting parasitism seen in our samples and use of this upland Tewksbury Unit by adult dragonflies.

Suggested Reading

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

Cook, William M. and Robert D. Holt. 2006. Fire frequency and mosaic burning effects on a tallgrass prairie ground beetle assemblage. Biodiversity and Conservation 15 (7): 2301-2323.