Forb, Insect, and Soil Response to Burning and Mowing Wyoming Big Sagebrush in Greater Sage-Grouse Breeding Habitat

Abstract

Wyoming big sagebrush (Artemisia tridentata wyomingensis A. t. Nutt. ssp. wyomingensis Beetle and Young) communities provide structure and forbs and insects needed by greater sage-grouse (Centrocercus urophasianus) for growth and survival. We evaluated forb, insect, and soil responses at six mowed and 19 prescribed burned sites compared to 25, paired and untreated reference sites. Sites were classified by treatment type, soil type, season, and decade of treatment (sites burned during 1990-1999 and sites burned or mowed during 2000-2006). Our objective was to evaluate differences in ten habitat attributes known to influence sage-grouse nesting and brood rearing to compare responses among treatment scenarios. Contrary to desired outcomes, treating Wyoming big sagebrush through prescribed burning or mowing may not stimulate cover or increase nutrition in food forbs, or increase insect abundance or indicators of soil quality compared with reference sites. In some cases, prescribed burning showed positive results compared with mowing such as greater forb crude protein content (%), ant (Hymenoptera; no./trap), beetle (Coleoptera/no./trap), and grasshopper abundance (Orthoptera; no./sweep), and total (%) soil carbon and nitrogen, but of these attributes, only grasshopper abundance was enhanced at burned sites compared with reference sites in 2008. Mowing did not promote a statistically significant increase in sage-grouse nesting or early brood-rearing habitat attributes such as cover or nutritional quality of food forbs, or counts of ants, beetles, or grasshoppers compared with reference sites.