Effects of Urine Deposition on Small‐Scale Patch Structure in Prairie Vegetation

Abstract

Large grazing mammals contribute to the species diversity of grasslands via direct and indirect effects of defoliation and urine deposition. We examined the influence of one and two applications of simulated bovine urine on vegetation structure on (1) tallgrass prairie burned either every 2 or 4 yr at Konza Prairie Research Natural Area (KPRNA), Kansas, and (2) unburned sandhills prairie at the Niobrara Valley Preserve, Nebraska. We also examined the influence of urine and the clipping of graminoids on an annually burned site at KPRNA. Plant abundance in general increased on urine patches but the response appeared dependent on litter accumulation. C4 grasses increased at the annual burn and Niobrara sites where litter levels were low. C3 forbs increased at the 2— and 4—yr burn sites where litter levels were high. Urine treatment significantly affected community composition at all but the 2—yr burn site. Alpha—diversity decreased on urine patches at the annual and 4—yr burn sites but increased on urine patches at the Niobrara site. Beta—diversity increased on urine patches at the annual burn and Niobrara site but decreased on urine patches at the 4—yr burn site. The clipping of graminoids at the annual burn site reduced both α— and β—diversity and graminoid abundance while forb abundance was not affected.