Brad Schultz

CASE STUDY: Reducing cheatgrass (Bromus tectorum L.) fuel loads using fall cattle grazing

Wildfire is a major concern in the Intermountain West. Fuels management can lower the potential for negative wildfire effects. Cheatgrass (Bromus tectorum L.), a nonnative annual grass, invasion has resulted in a buildup of highly flammable fine fuels that promote frequent wildfire. Removal of cheatgrass standing crop through targeted, prescriptive grazing should provide a reduction in fire intensity and possibly frequency on a local basis. Spring cattle-grazing prescriptions have provided critical reductions in cheatgrass standing crop and seed production. However, annual fluctuations in timing of readiness and standing crop production pose planning difficulties for both producers and land managers. With fall grazing, the uncertainties are no longer planning obstacles. We examined the effects of pasture-scale fall grazing of cheatgrass by cattle on standing crop (fuel reduction), the perennial vegetation community, and cattle performance. Fall grazing removed significant amounts of cheatgrass standing crop during 2006 to 2009: 79, 80, 79, and 58%, respectively. Cumulatively, 675 kg/ha were removed from the fuel base, significantly reducing carryover fuels. With protein supplementation, cattle increased BCS and gained BW in all 3 yr of the assessment (0.17, 0.35, and 0.29 kg/d in 2007 to 2009, respectively). Cheatgrass seed bank decreased by 6-fold in the grazed treatment and a little more than 2-fold in the ungrazed area 2007 to 2009. Perennial plants increased standing crop production at the expense of cheatgrass production. Fall grazing of cheatgrass can remove significant amounts of fine fuel with beneficial effects to grazing animals and the perennial plant community.

Mowing Wyoming Big Sagebrush (Artemisia tridentata ssp. wyomingensis) Cover Effects Across Northern and Central Nevada

ABSTRACT Many Wyoming big sagebrush (Artemisia tridentata Nutt. ssp. wyomingensis) communities are invaded by exotic annuals, especially cheatgrass (Bromus tectorum L.), promoting larger and more frequent wildfires. Mowing sagebrush can reduce fire risk. To identify community features favoring regeneration of native perennials over exotic annuals, we compared paired, adjacent unmowed and mowed areas treated between 2001 and 2010 at 76 sites across northern and central Nevada. We quantified soil surface and foliar cover in 12 cover groups, as well as slope, aspect, elevation, and time since mowing (0–10 years). We identified unmowed cover characteristics and site covariates that best predicted herbaceous cover in mowed areas and differences in herbaceous cover between adjacent mowed and unmowed areas. Mowed areas had significantly (P < 0.01) more absolute cover (%) of litter (14.6), perennial grasses (4.9), cheatgrass (2.0), and exotic forbs (1.1) and less sagebrush (-13.5), bare soil (-11.4), moss (-3.3), and rock (-0.8) than adjacent unmowed areas. Except for sagebrush, all cover group values were correlated between unmowed and mowed areas. The “perennial balance” (perennial minus annual herbaceous cover) was positive at 75% (57) of mowed areas and increased from unmowed to mowed areas at 51 sites. A positive perennial balance in mowed areas was more likely where paired unmowed areas lacked cheatgrass, had greater cover of perennial grass, and less of exotic forbs. Likewise, sites whose unmowed areas had > 30% sagebrush cover consisting of smaller plants had larger gains in perennial balance from unmowed to mowed areas. An increase in perennial balance from unmowed to mowed areas was more likely in central and northeastern Nevada and at sites mowed more recently. To encourage perennial grasses over annual herbaceous species in Wyoming big sagebrush communities, mowing is better suited to locales lacking exotic annuals and retaining ample cover of perennial grasses and sagebrush of smaller size.

Forum: A Framework for Resetting Wild Horse and Burro Management

On the Ground There are now over 130,000 head of wild horses and burros in the Bureau of Land Management program. Management tools in the original authorizations (Wild Horse and Burro Act; Public Rangelands Improvement Act) have been inhibited or banned by subsequent appropriation riders. The original framework for horse and burro management has been undermined, leading to on-range populations in excess of legally mandated levels. New, creative approaches to horse and burro management are required to bring populations back to legally mandated and ecologically appropriate levels.

Viewpoint: An Alternative Management Paradigm for Plant Communities Affected by Invasive Annual Grass in the Intermountain West

On the Ground Over 400,000 km2 of the Intermountain West is colonized by cheatgrass and other annual grasses. Planning and management actions designed to foster perennial grass health throughout the region have never addressed how annual grasses would respond. For decades, the most significant landscape-level management approach toward invasive annual grasses has been to complain. We now know how to begin the process of taking the Intermountain West back from the domination of invasive annual grasses: through the management of standing dead litter. Sustaining perennial bunchgrasses at landscape scales will require an integrated ecological approach to fuels management.

Climatic Influences on Establishment Pulses of Four Artemisia Species in Nevada

ABSTRACT Shrub recruitment in arid and semiarid regions often occurs in pulses controlled by specific weather events. Previous research suggested that Wyoming sagebrush in Wyoming is no exception. We examined four species/ subspecies of sagebrush in Nevada, in 2009 and 2010, to discover if evidence of recruitment pulses was contained in the annual growth-ring records. Sagebrush species and subspecies occur on a wide variety of ecological sites that require different management strategies. Species included black sagebrush (Artemisia nova A. Nelson), Wyoming big sagebrush (Artemisia tridentata subsp. wyomingensis Beetle & Young), Lahontan sagebrush (Artemisia arbuscula subsp. longicaulis Winward & McArthur), and low sagebrush (Artemisia arbuscula Nutt. ssp. arbuscula). Eighty stem sections were collected from each of 24 stands (6 stands per species or subspecies) at different geographic locations along east-west or north-south gradients where each species or subspecies naturally occurred. Annual growth-ring analysis was used to determine the year of establishment and the relationship between recruitment and weather events. Results indicated stand ages and locations were different (P > 0.001) among species and subspecies, and years of recruitment were strongly correlated with local and hemispheric weather patterns. Linear and multiple regressions modeled recruitment pulses for all four species. Weather-based predictor variables indicated complex interactions between recruitment and climatic controls. Pacific Decadal Oscillation (PDO) index variables were prominent predictors for all four species at their associated sites. Other important local weather variables included total annual precipitation the year before recruitment, the year of recruitment, and the year following recruitment. In Nevada and the Great Basin, it is imperative that successful sagebrush seeding technologies are discovered and implemented. Ecological restoration and postfire rehabilitation methods should be timed correctly with respect to precipitation patterns (positive phase PDO) and/ or designed to mimic conditions responsible for natural sagebrush recruitment.

Plant Community Factors Correlated with Wyoming Big Sagebrush Site Responses to Fire

ABSTRACT Fire kills Wyoming big sagebrush (Artemisia tridentata Nutt. ssp. wyomingensis Beetle & Young) and promotes cheatgrass (Bromus tectorum L.), a highly flammable and invasive annual in sagebrush communities with compromised resistance. To focus management on resistance and resilience of Wyoming big sagebrush communities with varying species composition, we studied 51 paired sites with burned and unburned areas. We quantified soil surface and foliar cover in 12 cover groups. Comparisons identified vegetation or soil surface factors that significantly (p ≤ 0.05) correlated (Spearmans rank correlation coefficient = ρ) to burned area community composition. Cheatgrass cover in burned areas was greater where unburned areas had more cheatgrass cover (ρ = 0.75), litter cover (ρ = 0.31), and sagebrush plant canopy volume (ρ = 0.40), and less bare soil (ρ=-0.39) and cryptogamcover (ρ=-0.32). Cheatgrass cover in burned areas was not significantly correlated with unburned area perennial grass or forb cover. Burned area perennial grass cover appeared to be related to more perennial grass (ρ = 0.77) and native forb cover (ρ = 0.30), but less cheatgrass cover (ρ = -0.39) in unburned areas. Burned area native herbaceous dominance (native minus exotic herbaceous foliar cover) correlated with less cheatgrass cover (ρ = -0.65) and sagebrush canopy volume (ρ = -0.34) in unburned areas and with more perennial grass (ρ = 0.30) and sagebrush relative cover (ρ = 0.39) in adjacent unburned areas. Postfire site dominance could be of either native or exotic plants where cheatgrass cover on adjacent unburned sites was < about 15%. Native species however, never dominated or increased in dominance where cheatgrass was above 15%. Results suggest that cheatgrass cover before a fire played a strong role in determining postfire plant communities; this suggests management should focus on prefire and postfire management of cheatgrass and litter. Perhaps prescriptions and priorities should bemore nuanced on the basis of driving variables of postfire response hypothesized to be cheatgrass, perennial grass, and shrub abundance.