Narrow hybrid zone between two subspecies of big sagebrush (Artemisia tridentata: Asteraceae). II. Selection gradients and hybrid fitness

The dynamic equilibrium hypothesis proposes that hybrid zones are stabilized by a balance between dispersal and selection against hybrids. A key prediction of this hypothesis is that hybrids should have lower fitness than either parental taxon, regardless of habitat. Hybrid big sagebrush (Artemisia tridentata ssp. tridentata × ssp. vaseyana) in two narrow hybrid zones do show greatly decreased recruitment. Hybrids in one zone also show increased browsing by grasshoppers, while those in the other zone have increased numbers of aphids. Overall herbivore loads, however, are not greater on the hybrids than on the parental subspecies. Browsing by mule deer is greatest on ssp. vaseyana in both hybrid zones. Incidence of galls is also greatest on ssp. vaseyana in one hybrid zone. Moreover, browsing by Artemisia weevils is greatest on ssp. tridentata in one hybrid zone. Hybrids produce more flowers than either ssp. tridentata or ssp. vaseyana, while seed production rates of hybrids do not differ from those of the parental taxa. Finally, hybrid seeds germinate as well as those of ssp. tridentata and better than those of ssp. vaseyana. Thus, our data do not support the dynamic equilibrium hypothesis.     

Annual nitrous oxide flux and soil nitrogen characteristics in sagebrush steppe ecosystems

Soil nitrogen transformations and nitrous oxide fluxes were measured in a range of sagebrush steppe ecosystems in south-central Wyoming. Net nitrate production, measured in laboratory incubations, was highest in the ecosystem type dominated by Artemisia tridentata ssp. vaseyana, especially early in the growing season. Fluxes of nitrous oxide, measured in closed chambers and analyzed by gas chromatography, also tended to be higher in the same type, but only for short periods in the spring. Thereafter, all nitrous oxide fluxes were low and did not differ consistently among types. Estimated average annual fluxes for three Artemisia ecosystem types (dominated by Artemisia tridentata ssp. vaseyana, Artemisia tridentata ssp. wyomingensis, and Artemisia nova) were 0.32, 0.23 and 0.13 kg N₂O-N ha^–1 y^–1 repsectively. Average annual flux, weighted by the areal extent of these and other vegetation types in the region, was approximately 0.21 kg N₂O-N ha^–1y^–1. Assuming this landscape is representative of sagebrush steppe, we calculate a flux of 9.5 × 10⁹ g y^–1 of N₂O-N from U.S. sagebrush steppe, and a flux of 1.1 × 10¹¹ g y^–1 of N₂0-N from analogous desert and semi-desert shrublands of the world.     

Prescribed fires in Artemisia tridentata ssp. vaseyana steppe have minor and transient effects on vegetation cover and composition

Question: What is the impact of prescribed fires on the cover and composition of vegetation in Artemisia tridentata ssp. vaseyana steppe? Location: United States Department of Agriculture, Agricultural Research Service, United States Sheep Experiment Station, eastern Idaho (44°14′44′’ N, 112°12′47′’ W). Methods: Multiple prescribed fires were lit in 2002 and 2003 in an Artemisia tridentata ssp. vaseyana (mountain big sagebrush) steppe ecosystem that was relatively free of exotic plants. Measurements of cover components and plant species frequencies were taken pre‐ and for 2 to 3 years post‐fire. Results: Cover of forbs and grasses returned to pre‐fire levels after two years. Shrub cover declined from 36 to 6% in the first year post‐fire. Fire reduced the frequencies of three species, A. tridentata ssp. vaseyana, Festuca idahoensis, and Cordylanthus ramosus, of rangeland plants. Frequencies of four plant species, Hesperostipa comata, Polygonum douglasii, Chenopodium fremontii and Chenopodium leptophyllum increased, but only P. douglasii increased for more than a year. Conclusion: This study demonstrates that in an Artemisia tridentata ssp. vaseyana steppe ecosystem without significant non‐native species or anthropogenic disturbances vegetative cover and species composition of the herbaceous community are only minimally altered by fire. The herbaceous component returned to pre‐fire conditions within three years of a fire.     

The chemical composition of the litter and soil in a community of Artemisia tridentata ssp. vaseyana

The leaves, litter, and soil from within a community of Artemisia tridentata ssp. vaseyana were analyzed for secondary metabolic products. Methacrolein, five monterpenes, three sesquiterpene lactones, six coumarins, and one flavonoid were identified in the leaves; the contents of the litter were nearly identical. Soils collected directly beneath the shrubs contained the three sesquiterpene lactones, two coumarins and an unknown flavonoid. The litter and water extracts of the litter inhibited the germination of sagebrush seeds. Soils charged with monoterpenes from sagebrush leaves also inhibited seed germination. In addition, the monoterpene contents from eight sagebrush taxa collected from Western Montana are reported.     

Restoring big sagebrush after controlling encroaching western juniper with fire: aspect and subspecies effects

The need for restoration of shrubs is increasingly recognized around the world. In the western United States, restoration of mountain big sagebrush (Artemisia tridentata Nutt. ssp. vaseyana [Rydb.] Beetle) after controlling encroaching conifers is a priority to improve sagebrush‐associated wildlife habitat. Conifers can be cost effectively removed with prescribed burning when sagebrush is codominant; however, burning removes sagebrush and natural recovery may be slow. We evaluated seeding mountain and Wyoming big sagebrush (A. tridentata Nutt. ssp. wyomingensis Beetle & Young) on north and south aspects after western juniper (Juniperus occidentalis ssp. occidentalis Hook) control with prescribed burning. We included seeding Wyoming big sagebrush, a more drought tolerant subspecies of big sagebrush, because it might grow better than mountain big sagebrush on hot, dry south slopes, during drought, or after juniper encroachment. Seeding mountain big sagebrush increased sagebrush cover and density compared to unseeded controls. In mountain big sagebrush‐seeded plots, sagebrush cover was 19 times greater on north compared to south aspects in the fourth year after seeding. At this time, sagebrush cover was also greater on mountain compared to Wyoming big sagebrush‐seeded plots. Natural recovery (i.e. unseeded) of sagebrush was occurring on north aspects with sagebrush cover averaging 3% 4 years after fire. Sagebrush was not detected on unseeded south aspects at the end of the study. These results suggest that postfire sagebrush recovery, with and without seeding, will be variable across the landscape based on topography. This study suggests seeding sagebrush after controlling junipers with burning may accelerate sagebrush recovery.     

Attempting to restore mountain big sagebrush (Artemisia tridentata ssp. vaseyana) four years after fire

Restoration of shrubs is needed throughout the world because of altered fire regimes, anthropogenic disturbance, and overutilization. The native shrub mountain big sagebrush (Artemisia tridentata Nutt. ssp. vaseyana (Rydb.) Beetle) is a restoration priority because of its value to wildlife in western North America. One of the principal threats to mountain big sagebrush is encroachment by western juniper (Juniperus occidentalis ssp. occidentalis Hook) and other conifers. Fire is frequently applied to control juniper; however, sagebrush recovery after fire can be variable. Seeding sagebrush postfire can hasten sagebrush recovery; however, seeding is not always necessary. Therefore, it may be advantageous to monitor postfire recovery to determine if seeding is needed. The effect of seeding sagebrush several years after fire is unknown. We evaluated the efficiency of seeding mountain big sagebrush four years after fire‐controlled junipers at five sites. Sagebrush cover (<0.5%) and density (<0.07 plants/m²) was low in seeded plots and did not differ from unseeded controls in the three postseeding years. We conclude that seeding sagebrush four years after fire did not accelerate sagebrush recovery. We speculate that seeded sagebrush failed to establish because of competition from herbaceous vegetation that had four years to recover after fire. Although it would be beneficial to seed sagebrush only when needed, our results suggest postponing seeding until monitoring has determined that recovery is inadequate may not be advisable. We suggest researchers investigate methods to improve predicting sagebrush recovery to allow for seeding, when needed, before the first postfire growing season.     

Short- and Long-term Changes in Elk Use and Forage Production in Sagebrush Communities Following Prescribed Burning

Burning shrub and grassland communities often leads to increases in plant production and nutritional quality that benefit herbivores, resulting in increased herbivore use of burned areas. Increased use has been ascribed more specifically to changes in plant community structure, community composition and diversity, nutritional quality, and seasonal availability. These hypotheses can be evaluated more precisely if changes in plant communities following burning are monitored concurrently with changes in herbivore use, especially in longer-term studies. From 1988 to 1999, we examined responses of elk (Cervus elaphus) following prescribed burning of areas burned in 1984 and 1988 that had been formerly dominated by mountain big sagebrush (Artemisia tridentata ssp. vaseyana) in south-central Montana (USA), with concurrent monitoring of changes in plant production, nutritional quality, and community composition. Elk made increased use of burned sites up to 15 years after burning. Burning transformed big sagebrush-dominated communities into native herbaceous communities that persisted for 15 years without sagebrush reinvasion. Forage biomass and protein content remained higher on burned sites for 15 years, although differences were not significant in every year and declined as time elapsed after burning. Forage production, forage protein, and elk use were temporally correlated, suggesting the possibility that grazing by elk might have contributed to persistence of elevated plant production and protein levels on burned sites.     

Postfire vegetation dynamics in a sagebrush steppe in southeastern Idaho,USA

Postburn vegetation in an Artemisia tripartita and A. tridentata sagebrush community one year after the burn was compared with unburned vegetation. While the vegetal cover amounted to 38.1% of the total area on the burned site, it was 91.1% on the unburned site. Dominance-diversity curves for plant communities on both sites approach the niche pre-emption hypothesis or geometric series. Cover values and soil residual propagule data were used to suggest mechanisms of persistence of the more prominent species through fire using Noble & Slatyer's (1980) Vital Attributes model. The first year postfire vegetation was dominated by forbs and grasses with vegetative and propagule storage mechanisms of persistence. Such information on succession mechanisms should be of benefit to range managers.     

Inferences for life history strategies of Artemisia tridentata subspecies

Communities dominated by Artemisia tridentata ssp. tridentata, A. tridentata ssp. wyomingensis, and A. tridentata ssp. vaseyana, found in the Piceance Basin of western Colorado, were evaluated for life history strategy. Species cover data were analyzed using Grime's (1984) triangular model. Then a canonical analysis was conducted to obtain an ordination of relative species cover. Results from these two analyses were then used to infer strategy differences among life histories of subspecies, based on the respective plant community associates. These differences were found to be consistent with the divergent evolution assumed to have occurred in this species. The primary ordination axis was interpreted as an elevation-moisture gradient. Further analysis of soil data by factor analysis also separated the three Artemisia subspecies along a soil texture gradient.     

Sesquiterpene lactones of Artemisia: TLC analysis and taxonomic significance

Samples of Artemisia arbuscula ssp. arbuscula, A. tridentata ssp. tridentata, ssp. wyomingensis, ssp. vaseyana and ssp. vaseyana f. spiciformis were collected from various locations in Montana and analyzed by TLC for their sesquiterpene lactone content. Artemisia tridentata ssp. tridentata and ssp. wyomingensis are distinct morphologically and chemically, whereas ssp. vaseyana has three distinct chemical groups not yet separated morphologically. Artemisia arbuscula ssp. arbuscula and A. tridentata ssp. vaseyana f. spiciformis are easily separated by morphology but have identical TLC patterns. It has been further shown that the sesquiterpene lactones produced for a particular species or subspecies are the same regardless of the time of the year collected, although the quantity varies from winter to summer.     

Postwildfire seeding to restore native vegetation and limit exotic annuals: an evaluation in juniper‐dominated sagebrush steppe

Reestablishment of perennial vegetation is often needed after wildfires to limit exotic species and restore ecosystem services. However, there is a growing body of evidence that questions if seeding after wildfires increases perennial vegetation and reduces exotic plants. The concern that seeding may not meet restoration goals is even more prevalent when native perennial vegetation is seeded after fire. We evaluated vegetation cover and density responses to broadcast seeding native perennial grasses and mountain big sagebrush (Artemisia tridentata Nutt. spp. vaseyana [Rydb.] Beetle) after wildfires in the western United States in six juniper (Juniperus occidentalis ssp. occidentalis Hook)‐dominated mountain big sagebrush communities for 3 years postfire. Seeding native perennial species compared to not seeding increased perennial grass and sagebrush cover and density. Perennial grass cover was 4.3 times greater in seeded compared to nonseeded areas. Sagebrush cover averaged 24 and less than 0.1% in seeded and nonseeded areas at the conclusion of the study, respectively. Seeding perennial species reduced exotic annual grass and annual forb cover and density. Exotic annual grass cover was 8.6 times greater in nonseeded compared to seeded areas 3 years postfire. Exotic annual grass cover increased over time in nonseeded areas but decreased in seeded areas by the third‐year postfire. Seeded areas were perennial‐dominated and nonseeded areas were annual‐dominated at the end of the study. Establishing perennial vegetation may be critical after wildfires in juniper‐dominated sagebrush steppe to prevent the development of annual‐dominated communities. Postwildfire seeding increased perennial vegetation and reduced exotic plants and justifies its use.     

Edaphic limitations to growth and photosynthesis in Sierran and Great Basin vegetation

Summary Soils derived from hydrothermally altered andesite support unique communities of Sierran conifers (Pinus ponderosa Laws. and P. jeffreyi Grev. and Balf.) amongst sagebrush (Artemisia tridentata Nutt.) vegetation in the western Great Basin. Plants grown in soil derived from hydrothermally altered bedrock had lower growth rates, total biomass, and net photosynthetic rates than plants grown in soil derived from unaltered andesite of the same formation. Total dry mass was 10 to 28% lower for conifers grown in altered soil whereas dry mass of Artemisia tridentata and Bromus tectorum L. was reduced by over 90%. Results from a nutrient amendment experiment indicated that low phosphorus was the dominant limitation in altered soil, and phosphorus-deficiency affected growth primarily by limiting leaf area development rather than direct inhibition of photosynthesis. The proportionately greater reduction of biomass for Artemisia and Bromus grown in altered soil supports our hypothesis that Great Basin vegetation is excluded from altered soil by intolerance to nutrient deficiency. The Sierran conifers growing on this rock type are therefore free of competition for water with Great Basin vegetation and are able to persist in an exceptionally dry climate.     

CHARACTERIZATION OF A NARROW HYBRID ZONE BETWEEN TWO SUBSPECIES OF BIG SAGEBRUSH (ARTEMISIA TRIDENTATA: ASTERACEAE)

Hybridization between Artemisia tridentata ssp. tridentata and A. t. ssp. vaseyana occurs in a narrow elevational zone along the west face and canyons of the Wasatch Mountains of Utah. Two sites in central Utah (Orem and Salt Creek) were examined. The parental taxa differ in anatomy, morphology, flavonoid and coumarin content, as well as various growth parameters. Hybrids are intermediate for the majority of traits examined, including flavonoid and coumarin composition. Multivariate statistics show that these taxa can be unambiguously identified using simple field measures of morphology. A hybrid index was constructed using principal component analyses on morphological variables.     

Conversion of sagebrush shrublands to exotic annual grasslands negatively impacts small mammal communities

Aim The exotic annual cheatgrass (Bromus tectorum) is fast replacing sagebrush (Artemisia tridentata) communities throughout the Great Basin Desert and nearby regions in the Western United States, impacting native plant communities and altering fire regimes, which contributes to the long‐term persistence of this weedy species. The effect of this conversion on native faunal communities remains largely unexamined. We assess the impact of conversion from native perennial to exotic annual plant communities on desert rodent communities. Location Wyoming big sagebrush shrublands and nearby sites previously converted to cheatgrass‐dominated annual grasslands in the Great Basin Desert, Utah, USA. Methods At two sites in Tooele County, Utah, USA, we investigated with Sherman live trapping whether intact sagebrush vegetation and nearby converted Bromus tectorum‐dominated vegetation differed in rodent abundance, diversity and community composition. Results Rodent abundance and species richness were considerably greater in sagebrush plots than in cheatgrass‐dominated plots. Nine species were captured in sagebrush plots; five of these were also trapped in cheatgrass plots, all at lower abundances than in the sagebrush. In contrast, cheatgrass‐dominated plots had no species that were not found in sagebrush. In addition, the site that had been converted to cheatgrass longer had lower abundances of rodents than the site more recently converted to cheatgrass‐dominated plots. Despite large differences in abundances and species richness, Simpson’s D diversity and Shannon‐Wiener diversity and Brillouin evenness indices did not differ between sagebrush and cheatgrass‐dominated plots. Main conclusions This survey of rodent communities in native sagebrush and in converted cheatgrass‐dominated vegetation suggests that the abundances and community composition of rodents may be shifting, potentially at the larger spatial scale of the entire Great Basin, where cheatgrass continues to invade and dominate more landscape at a rapid rate.     

Deep sequencing of amplicons reveals widespread intraspecific hybridization and multiple origins of polyploidy in big sagebrush (Artemisia tridentata; Asteraceae)

• Premise of the study: Hybridization has played an important role in the evolution and ecological adaptation of diploid and polyploid plants. Artemisia tridentata (Asteraceae) tetraploids are extremely widespread and of great ecological importance. These tetraploids are often taxonomically identified as A. tridentata subsp. wyomingensis or as autotetraploids of diploid subspecies tridentata and vaseyana. Few details are available as to how these tetraploids are formed or how they are related to diploid subspecies. • Methods: We used amplicon sequencing to assess phylogenetic relationships among three recognized subspecies: tridentata, vaseyana, and wyomingensis. DNA sequence data from putative genes were pyrosequenced and assembled from 329 samples. Nucleotide diversity and putative haplotypes were estimated from the high-read coverage. Phylogenies were constructed from Bayesian coalescence and neighbor-net network analyses. • Key results: Analyses support distinct diploid subspecies of tridentata and vaseyana in spite of known hybridization in ecotones. Nucleotide diversity estimates of populations compared to the total diversity indicate the relationships are predominately driven by a small proportion of the amplicons. Tetraploids, including subspecies wyomingensis, are polyphyletic occurring within and between diploid subspecies groups. • Conclusions: Artemisia tridentata is a species comprising phylogenetically distinct diploid progenitors and a tetraploid complex with varying degrees of phylogenetic and morphological affinities to the diploid subspecies. These analyses suggest tetraploids are formed locally or regionally from diploid tridentata and vaseyana populations via autotetraploidy, followed by introgression between tetraploid groups. Understanding the phylogenetic vs. ecological relationships of A. tridentata subspecies will have bearing on how to restore these desert ecosystems.     

Restoring riparian meadows currently dominated by Artemisa using alternative state concepts ‐ above‐ground vegetation response

Abstract. Livestock overgrazing and stream incision in the western USA often result in encroachment and dominance of Artemisia tridentata ssp. tridentata (Big sagebrush) in riparian areas that formerly supported meadows. To define the alternative states and thresholds for these ecosystems, we conducted a restoration experiment that included sites with high, intermediate or low water tables. We used a paired‐plot approach in which one plot on each site was burned and seeded with native grasses and forbs typical of naturally occurring dry meadow and Artemisia/Leymus cinereus ecological types, while adjacent unburned plots served as controls. Sites with high and intermediate water tables had greater initial abundances of perennial grasses typical of dry meadows, such as Leymus triticoides and Poa secunda ssp. juncifolia, and these species increased after the burn. In contrast, sites with low water tables were dominated by annual forbs such as Chenopo‐dium album and Descurainia pinnata after the burn. Biomass increased progressively from 1997 to 1999 on burned plots, while controls showed little change. Burning effects were microsite specific, with former Artemisia microsites exhibiting lower biomass than interspaces initially, but similar or higher biomass by the third year. Establishment of seeded species was low and species composition was determined largely by pre‐burn vegetation. Artemisia dominated sites with high water tables appear to represent an alternative state of the dry meadow ecological type, while sites with low water table sites have crossed an abiotic threshold governed by water tables and represent a new ecological type. Burning is an effective tool for restoring relatively high water table sites, but low water table sites will require burning and seeding with species adapted to more xeric conditions.     

Narrow hybrid zone between two subspecies of big sagebrush (Artemisia tridentata: Asteraceae)

Several species of gall-forming insects specialize on big sagebrush (Artemisia tridentata), a species that shows much clinal and subspecific variation throughout its geographic range. Two of those subspecies, basin big sagebrush (A. t. ssp. tridentata) and mountain big sagebrush (A. t. ssp. vaseyana), form a narrow hybrid zone at Salt Creek, Utah. Reciprocal transplant experiments have shown that the hybrid big sagebrush at Salt Creek are more fit than either parental subspecies, but only in the hybrid zone. Do genotype and environment influence the density and distribution of galls on big sagebrush? We counted galls on parental and hybrid big sagebrush in three reciprocal transplant gardens at Salt Creek. Gardens were in each of the two parental zones and in the hybrid zone. Transplanted seedlings came from five source populations: two parental and three hybrid populations. We identified seven kinds of gall-forming flies (Rhopalomyia midges and Eutreta fruitflies) that produced identifiable galls. Densities of galls varied among the three gardens and five source populations, and there was also a significant garden by source interaction in gall density. In general, variation in gall density among gardens (i.e., environments) was much greater than the variation among source populations (i.e., genotypes). Nevertheless, significant genotype-environment interactions were observed for five of the seven kinds of galls. Overall density of galls, mostly due to Rhopalomyia ampullaria, was greatest in the high-elevation (mountain) garden and least in the low-elevation (basin) garden. To the best of our knowledge, this is the first reciprocal transplant experiment addressing herbivore richness in a hybrid zone.     

Fire Effects on Cover and Dietary Resources of Sage-Grouse Habitat

Abstract: We evaluated 6 years of vegetation response following prescribed fire in Wyoming big sagebrush (Artemisia tridentata spp. wyomingensis) steppe on vegetation cover, productivity, and nutritional quality of forbs preferred by greater sage-grouse (Centrocercus urophasianus), and abundance of common arthropod orders. Habitat cover (shrubs and tall herbaceous cover [>18 cm ht]) was about 50% lower after burning compared to unburned controls because of the loss of sagebrush. Perennial grasses and an invasive annual forb, pale alyssum (Alyssum alyssoides), increased in cover or yield after fire. There were no increases in yield or nutritional quality of forb species important in diets of sage-grouse. Abundance of ants (Hymenoptera), a significant component in the diet of young sage-grouse, decreased after fire. These results suggest that prescribed fire will not improve habitat characteristics for sage-grouse in Wyoming big sagebrush steppe where the community consists of shrubs, native grasses, and native forbs.     

Studies on the microbial populations of the rhizosphere of big sagebrush (<Emphasis Type="Italic">Artemisia tridentata</Emphasis>)

Prolonged use of broad-spectrum antibiotics has led to the emergence of drug-resistant pathogens, both in medicine and in agriculture. New threats such as biological warfare have increased the need for novel and efficacious antimicrobial agents. Natural habitats not previously examined as sources of novel antibiotic-producing microorganisms still exist. One such habitat is the rhizosphere of desert shrubs. Here, we show that one desert shrub habitat, the rhizosphere of desert big sagebrush (Artemisia tridentata) is a source of actinomycetes capable of producing an extensive array of antifungal metabolites. Culturable microbial populations from both the sagebrush rhizosphere and nearby bulk soils from three different sites were enumerated and compared, using traditional plate-count techniques and antibiotic activity bioassays. There were no statistical differences between the relative numbers of culturable non-actinomycete eubacteria, actinomycetes and fungi in the rhizosphere versus bulk soils, but PCR amplification of the 16S rRNA gene sequences of the total soil DNA and denaturing gradient gel electrophoresis showed that the community structure was different between the rhizosphere and the bulk soils. A high percentage of actinomycetes produced antimicrobials; and the percentage of active producers was significantly higher among the rhizosphere isolates, as compared with the bulk soil isolates. Also, the rhizosphere strains were more active in the production of antifungal compounds than antibacterial compounds. 16S rRNA gene sequence analysis showed that sagebrush rhizospheres contained a variety of Streptomyces species possessing broad spectrum antifungal activity. Scanning electron microscopy studies of sagebrush root colonization by one of the novel sagebrush rhizosphere isolates, Streptomyces sp. strain RG, showed that it aggressively colonized young sagebrush roots, whereas another plant rhizosphere-colonizing strain, S. lydicus WYEC108, not originally isolated from sagebrush, was a poor colonizer of the roots of this plant, as were two other Streptomyces isolates from forest soil. These results support the hypothesis that the rhizosphere of desert big sagebrush is a promising source of habitat-adapted actinomycetes, producing antifungal antibiotics.     

Attempting to Restore Herbaceous Understories in Wyoming Big Sagebrush Communities with Mowing and Seeding

Shrub steppe communities with depleted perennial herbaceous understories often need to be restored to increase resilience and resistance. Mowing has been applied to Wyoming big sagebrush (Artemisia tridentata Nutt. ssp. wyomingensis Beetle & Young) steppe plant communities to reduce sagebrush dominance and restore native herbaceous vegetation, but success has been limited and hampered by increases in exotic annuals. Seeding native bunchgrasses after mowing may accelerate recovery and limit exotics. We compared mowing followed by drill‐seeding native bunchgrasses to mowing and an untreated control at five sites in southeastern Oregon over a 4‐year period. Mowing and seeding bunchgrasses increased bunchgrass density; however, bunchgrass cover did not differ among treatments. Exotic annuals increased with mowing whether or not post‐mowing seeding occurred. Mowing, whether or not seeding occurred, also reduced biological soil crusts. Longer term evaluation is needed to determine if seeded bunchgrasses will increase enough to suppress exotic annuals. Seeded bunchgrasses may have been limited by increases in exotic annuals. Though restoration of sagebrush communities with degraded understories is needed, we do not recommend mowing and seeding native bunchgrasses because this treatment produced mixed results that may lower the resilience and resistance of these communities. Before this method is applied, research is needed to increase our understanding of how to improve establishment of seeded native bunchgrasses. Alternatively, restoration practitioners may need to apply treatments to control exotic annuals and repeatedly seed native bunchgrasses.