Sagebrush
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Abstracts of Recent Papers on Range Management in the West. Prepared by Charlie Clements, Rangeland Scientist, USDA Agricultural Research Service, Reno, NV.
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Sage grouse are the ‘canary in the coal mine’ that herald how this vital ecosystem is faring. These birds rely entirely on sagebrush-dominated landscapes: it’s their primary food source, their breeding grounds, their chick-rearing sites, their safe zones from hungry predators.
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This study quantitatively characterized the floral guilds of 17 prevalent wildflower species of the Great Basin that are, or could be, available for restoration seed mixes. More than 3800 bees representing >170 species were sampled from >35,000 plants. Species of Osmia, Andrena, Bombus, Eucera, Halictus, and Lasioglossum bees prevailed. The most thoroughly collected floral guilds, at Balsamorhiza sagittata and Astragalus filipes, comprised 76 and 85 native bee species, respectively. Pollen-specialists dominated guilds at Lomatium dissectum, Penstemon speciosus, and several congenerics. In contrast, the two native wildflowers used most often in sagebrush steppe seeding mixes—Achillea millefolium and Linum lewisii—attracted the fewest bees, most of them unimportant in the other floral guilds. Successfully seeding more of the other wildflowers studied here would greatly improve degraded sagebrush steppe for its diverse native bee communities.
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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 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.
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In this study, a multivariate dataset was analyzed using principal components analysis to identify “defining factors” that best explained variation among sites. Variation was primarily attributed to an inverse relationship between crested wheatgrass and sagebrush abundance (R2 = 0.69; P < 0.0001) and their affinity for either silty or sandy soil textures, respectively, as well as a negative association between crested wheatgrass abundance and species diversity (R2 = 0.67; P < 0.0001). These results do not support the assumption that crested wheatgrass seedings uniformly remain in vegetation states with low diversity and poor sagebrush reestablishment over the long term (i.e., 43 − 63 yr). We suggest that a broader interpretation of plant community dynamics is needed while avoiding generalizations of how historically seeded Wyoming big sagebrush sites will respond over time.
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The objective of this study was to investigate how climate, land use and community structure may explain these patterns of species dominance. We found that differences in summer precipitation and winter minimum temperature, land use intensity, and shrub size may all contribute to the dominance of annual species in the Great Basin, particularly cheatgrass. In particular, previous work indicates that summer precipitation and winter temperature drive the distribution of cheatgrass in the Great Basin. As a result, sites with wet summers and cold springs, similar to the Chinese sites, would not be expected to be dominated by cheatgrass. A history of more intense grazing of the Chinese sites, as described in the literature, also is likely to decrease fire frequency, and decreases litter and shrub dominance, all of which have been demonstrated to be important in cheatgrass establishment and ultimate dominance. Further research is necessary to determine if other annuals that follow the same pattern of scarcity in the Junggar Basin and dominance in the Great Basin are responding to the same influences.
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Grazing exacerbates Bromus tectorum dominance in one of North America’s most endangered ecosystems by adversely impacting key mechanisms mediating resistance to invasion. If the goal is to conserve and restore resistance of these systems, managers should consider maintaining or restoring: (i) high bunchgrass cover and structure characterized by spatially dispersed bunchgrasses and small gaps between them; (ii) a diverse assemblage of bunchgrass species to maximize competitive interactions with B. tectorum in time and space; and (iii) biological soil crusts to limit B. tectorum establishment. Passive restoration by reducing cumulative cattle grazing may be one of the most effective means of achieving these three goals.
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This fact sheet provides managers with strategies to reduce the spread and impact of medusahead.
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View fact sheet, pg. 37.
Bareroot or container seedlings can be used to quickly re-establish big sagebrush and other native shrubs in situations where direct seeding is not feasible or unlikely to succeed. Guidelines are provided for developing a planting plan and timeline, arranging for seedling production, and installing and managing outplantings.
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View fact sheet, pg. 33.
This fact sheet provides guidelines for maintaining productive sagebrush steppe communities in grazed areas after fire. The focus is on plant communities that, prior to fire, were largely intact and had an understory of native perennial herbaceous species or introduced bunchgrass, rather than invasive annual grass.
View all topics reviewed in the Fact Sheet series.