Northern Prairie Wildlife Research Center
University of Missouri, The School of Natural Resources, 112 Stephens Hall, Columbia, MO 65211; University of Missouri, The School of Natural Resources, 112 Stephens Hall, Columbia, MO 65211; U.S. Fish and Wildlife Service, Lostwood National Wildlife Refuge, Rural Route 2, Box 98, Kenmare, ND 58746
Vegetation encroachment at piping plover (Charadrius melodus) breeding beaches has the potential to substantially reduce available nesting sites for this federally-listed threatened species. Nesting piping plovers require unvegetated or sparsely-vegetated gravel and sand beaches located adjacent to alkaline wetlands. The relatively high number of plovers breeding at alkaline wetlands suggests that management actions to reduce vegetative cover at these sites may substantially increase nesting productivity across the northern Great Plains. Recent management practices, including prescribed burning and applications of salt, have seemingly increased piping plover nesting effort and success at alkaline beaches at Lostwood National Wildlife Refuge in northwestern North Dakota. To further evaluate these effects, we initiated a study in 1992 at the John E. Williams Memorial Nature Preserve, McLean County, North Dakota. Treatments at 1,080 1-m2 plots included prescribed burning and a combination of burning plus three levels of salt application (0.5, 1.5, and 3.0 kg/m2 applied as dry pellets); treatments were conducted in late April (pre-greenup) and mid-July (post-greenup). All plots were dominated by inland saltgrass (Distichlis spicata), which was the most common grass species occurring at plover nesting beaches. Plots were distributed among gravel, sand, and mud substrates, and soil salinity was measured at each plot. Two-thirds of the plots were re-treated in 1993 to evaluate multi-year treatment effects. We measured percent foliar cover and height of vegetation at four-week intervals post-treatment. Analyses of 1992 data indicated a reduction in both foliar cover and height for all treatments relative to untreated control plots (P = 0.0001). April treatments reduced foliar cover by 75-81%, 26-39%, and 18-35% after 4, 8, and 16 weeks, respectively; control plots increased 6, 28, and 33% during the same intervals. July treatments reduced foliar cover 90-92% after four weeks, whereas control plots increased by 2%. The three kg/m2 salt treatment had the greatest effect on vegetative cover. Treatment effects were similar among substrate types, except that April-August 1992 vegetative growth on gravel plots (including controls) was markedly higher than on sand and mud plots. Preliminary results indicate that foliar cover increased 9-38% from April 1992 to April 1993 on treated plots, whereas control plots increased 53%. July 1992 treatments maintained 71-78% reduction of foliar cover as of April 1993; control plots increased 16% during the same interval. Results from re-application of treatments in 1993 will be presented.