Restoration
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Using a wet thermal time model for germination prediction, this study estimated progress toward germination (PTG) of 31 seedlots (10 species) as a function of hourly seedbed temperature (> 0 °C) when soils were above a water potential of −1.5 MPa. Seasonally-summed progress toward germination with a value > 1 indicates that germination will occur for that season. We used near surface (1–3 cm) soil water potential and temperature measurements collected at 24 sites in the Great Basin to determine effects of site, season, and year on PTG. On tree encroached sites, we also determined effects of tree infilling phase at time of tree removal, removal method, and microsite on estimated PTG. Soils were wet and warm enough in early spring, late spring, and fall for PTG > 1 indicating potential germination for most seedlots and species on most sites and years. Prescribed burning increased PTG as much as three times more than either tree cutting or mechanical shredding. Germination prediction could help to screen for plant materials adapted to specific sites or assess effects of seed additives or treatments that time germination to maximize seedling survival.
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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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Fourteen wildland seed collections of Utah lotus originating from Nevada and Utah were assessed for genetic variation of a wide range of phenotypic traits and genetic relationships. Population structure estimates defined by 552 amplified fragment length polymorphism (AFLP) markers identified three primary subgroups within the Utah lotus collections, which corresponded to their geographic origin. Two collections of Utah lotus (LU-5 and LU-20) were among the top-performing collections for the phenotypic traits examined, including dry-matter yield, pod production, number of stems, canopy height, and persistence.
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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.
View Chapter 12 of the book, Exotic brome-grasses in arid and semiarid ecosystems of the western US: causes, consequences, and management implications.
Invasive annual grass research and management in arid and semiarid ecosystems of the Western United States (USA) have historically focused on reducing weed abundance as opposed to ecosystem restoration, which addresses the underlying processes responsible for their persistence. Given the current impact of invasive annual grasses and their continued spread in this region, we identified common characteristics responsible for persistence of the most problematic exotic annual Bromus. For heavily invaded areas, these include transient, yet typically large seed banks, altered soil resource availability and litter production, displacement of native species, and frequent disturbance from fire. To better address these common characteristics for future management, we illustrate how an adaptive management framework can reduce existing uncertainty associated with the restoration of arid and semiarid ecosystems.
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Time-controlled, short-duration, high intensity sheep or cattle grazing for several days in early spring removes substantial amounts of alien annual plant seed while it is still in inflorescence and opens up the sward canopy to allow light to penetrate to young, short-statured seedling perennials. This grazing event must be timed to allow perennial grass regrowth, flowering and seed set before spring soil moisture is exhausted. It must be intense enough to graze off the grass inflorescences of most alien annual grasses. The result is increased live crown cover for mature perennial grasses, reduced decadent dead-center growth forms in bunchgrasses, and improved light availability to tiller bases which promotes basal bud activation and new vegetative and reproductive tiller formation. These perennial grass responses constitute what managers term improved plant vigor.
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. 12.
This fact sheet provides managers with tools and strategies to reestablish perennial-dominated plant communities in medusahead-invaded sagebrush rangelands.
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View fact sheet, pg. 60.
This fact sheet provides land managers with information that can help identify different aspen types, assess the condition of aspen stands, and prioritize stands for restoration using appropriate treatments.
View all topics reviewed in the Fact Sheet series.