The 2008 Joint Meeting of the Society for Range Management and the America Forage and Grassland Council. |
Tuesday, January 29, 2008
35
Effects of Season of Fire and Grazing on Japanese Brome
Jennifer M. Muscha and Lance T. Vermeire. ARS, Fort Keogh Livestock and Range Research Laboratory, 243 Fort Keogh Rd., Miles City, MT 59301
Japanese brome (Bromus japonicus) is an invasive annual grass known to reduce perennial grass production in the northern Great Plains. Its annual life cycle and dependence on moist conditions for fall germination may leave them susceptible to grazing and fire management. Our objective was to determine the effects of summer, fall, or spring fire and spring grazing on Japanese brome. A factorial arrangement of two grazing and four fire treatments with four replicates was conducted. Fire treatments were applied 25 August, or 24 October 2006, or 26 March 2007. Grazing treatment was no grazing or 50% biomass removal by sheep one week after brome inflorescences emerged from the sheath (early June 2007). Warm-season grasses, other annual grasses, and forbs were not affected by fire. Japanese brome biomass was greater following summer fire (1024 ± 110 kg•ha-1) than other fire treatments (559 kg•ha-1). Japanese brome, other annual grass and forb biomass were reduced 41, 51, and 76% by grazing. Cool-season perennial grass biomass in non-grazed sites was greater following summer fire (728 ± 90 kg•ha-1) than fall, spring, or non-burned treatments (390 kg•ha-1). Grazing decreased cool-season grass biomass in summer, spring, and non-burned plots, such that all were similar across fire treatments (147 kg•ha-1). Total biomass in non-grazed sites was greater with summer fire (2246 ± 149 kg•ha-1) than other fire treatments (1302 kg•ha-1). In grazed plots, summer fire had more remaining biomass (1085 kg•ha-1) than spring and non-burned plots (654 kg•ha-1), with fall-burned plots being intermediate (815 kg•ha-1). Our earlier research indicated summer fire doubled western wheatgrass as we observed in this study, but it reduced annual bromes 50% rather than increasing them, so fire effects may interact with precipitation. It is too early to determine grazing effects on annual bromes, but sheep removed about 41% of brome biomass.