Search Results (27)

Background/Objectives: Pygmy rabbits (Brachylagus idahoensis) are closely associated with sagebrush steppe habitat across the western United States, and loss and fragmentation of this habitat has contributed to the near extirpation of the Columbia Basin population in Washington state (CB). The CB pygmy rabbit was listed under the Endangered Species Act in 2003, and recovery efforts have included captive breeding, reintroduction, and genetic rescue with the translocation of rabbits from populations across the species range. Methods: We used restriction site-associated DNA sequencing (RADseq) on samples from across the species range, including CB pygmy rabbits captured prior to genetic rescue and admixture. We determined population genetic structure across the pygmy rabbit range, tested for genomic signatures of adaptive divergence among populations, assessed the genetic distinctiveness of the ancestral CB population, and identified loci useful for monitoring ancestry in the current admixed CB population. Results: Our dataset included 9794 single-nucleotide polymorphisms (SNPs) across 123 individuals. We identified four distinct genetic groups, including the central portion of the species range and three peripheral populations: CB, northern Utah/Wyoming, and southern Utah. The ancestral CB population showed the highest degree of genetic distinctiveness using multiple clustering, ordination, and genetic differentiation analyses. We identified evidence for putatively adaptive variation among populations, but no significant gene ontology associated with local adaptation. Conclusions: Our results highlight the long-term isolation of the ancestral CB population as well as historical isolation of other peripheral populations. Our results also provide SNP loci for monitoring the consequences of genetic rescue efforts in the current admixed CB population. Full article

Background/Objectives: Loss and fragmentation of habitat from agricultural conversion led to the near extirpation of the pygmy rabbit (Brachylagus idahoensis Merriam, 1891) population in the Columbia Basin (CB) of Washington, USA. Recovery efforts began in 2002 and included captive breeding, translocations from other regions for genetic rescue, and reintroduction into native habitat in three sites: Sagebrush Flat (SBF), Beezley Hills (BH), and Chester Butte (CHB). Methods: We used noninvasive and invasive genetic sampling to evaluate demographic and population genetic parameters on three translocated populations of pygmy rabbits over eight years (2011–2020). For each population, our goal was to use fecal DNA sampling and 19 microsatellite loci to monitor spatial distribution, apparent survival rates, genetic diversity, reproduction, effective population size, and the persistence of CB ancestry. Over the course of this study, 1978 rabbits were reintroduced as part of a cooperative conservation effort between state and federal agencies. Results: Through winter and summer monitoring surveys, we detected 168 released rabbits and 420 wild-born rabbits in SBF, 13 released rabbits and 2 wild-born in BH, and 16 released rabbits in CHB. Observed heterozygosity (H_o) values ranged from 0.62–0.84 (SBF), 0.59–0.80 (BH), and 0.73–0.77 (CHB). Allelic richness (AR) ranged from 4.67–5.35 (SBF), 3.71–5.41 (BH), and 3.69–4.65 (CHB). Effective population (N_e) within SBF varied from 12.3 (2012) to 44.3 (2017). CB ancestry persisted in all three wild populations, ranging from 15 to 27%. CB ancestry persisted in 99% of wild-born juveniles identified in SBF. Apparent survival of juvenile rabbits differed across years (1–39%) and was positively associated with release date, release weight, and genetic diversity. Survival of adults (0–43%) was positively influenced by release day, with some evidence that genetic diversity also positively influenced adult apparent survival. Conclusions: Noninvasive genetic sampling has proven to be an effective and efficient tool in monitoring this reintroduced population, assessing both demographic and genetic factors. This data has helped managers address the goals of the Columbia Basin recovery program of establishing multiple sustainable wild populations within the sagebrush steppe habitat of Washington. Full article

Social conflict over rangeland-use priorities, especially near protected areas, has long pitted environmental and biodiversity conservation interests against livestock livelihoods. Social–ecological conflict limits management adaptation and creativity while reinforcing social and disciplinary divisions. It can also reduce rancher access to land and negatively affect wildlife conservation. Communities increasingly expect research organizations to address complex social dynamics to improve opportunities for multiple ecosystem service delivery on rangelands. In the Greater Yellowstone Ecosystem (GYE), an area of the western US, long-standing disagreements among actors who argue for the use of the land for livestock and those who prioritize wildlife are limiting conservation and ranching livelihoods. Researchers at the USDA-ARS US Sheep Experiment Station (USSES) along with University and societal partners are responding to these challenges using a collaborative adaptive management (CAM) methodology. The USSES Rangeland Collaboratory is a living laboratory project leveraging the resources of a federal range sheep research ranch operating across sagebrush steppe ecosystems in Clark County, Idaho, and montane/subalpine landscapes in Beaverhead County, Montana. The project places stakeholders, including ranchers, conservation groups, and government land managers, in the decision-making seat for a participatory case study. This involves adaptive management planning related to grazing and livestock–wildlife management decisions for two ranch-scale rangeland management scenarios, one modeled after a traditional range sheep operation and the second, a more intensified operation with no use of summer ranges. We discuss the extent to which the CAM approach creates opportunities for multi-directional learning among participants and evaluate trade-offs among preferred management systems through participatory ranch-scale grazing research. In a complex system where the needs and goals of various actors are misaligned across spatiotemporal, disciplinary, and social–ecological scales, CAM creates a structure and methods to focus on social learning and land management knowledge creation. Full article

Re-establishing native plants while controlling invasive species is a challenge for many dryland restoration efforts globally. Invasive plants often create highly competitive environments so controlling them is necessary for effective establishment of native species. In the sagebrush steppe of the United States, invasive annual grasses are commonly controlled with herbicide treatments. However, the same herbicides that control invasive annual grasses also impact the native species being planted. As such, carbon-based seed technologies to protect native seeds from herbicide applications are being trialed. In addition to controlling invasive species, ensuring good seed-to-soil contact is important for effective establishment of native species. In this grow room study, we explored the impact of different seed ameliorations when no herbicide was applied and when herbicide was applied. We selected two native species that are important to the sagebrush steppe for this study—the sub-shrub Krascheninnikovia lanata and the perennial bunchgrass Pseudoroegneria spicata—and used three different seed ameliorations—seed pelleting with local soil alone, local soil plus activated carbon and activated carbon alone—to ensure both greater seed-to-soil contact and protection against herbicides. Shoot and root biomass data were collected eight weeks after planting. We found that when herbicide was not applied, K. lanata had the strongest response to the soil alone amelioration, while P. spicata had the strongest response to the activated carbon alone amelioration. However, when herbicide was applied, K. lanata performed best with the soil plus activated carbon treatments, with an average 1500% increase in biomass, while P. spicata performed best with the activated carbon alone treatments, with an over 4000% increase in biomass, relative to bare seed. The results from our study indicate that there is a positive effect of local soils and activated carbon as seed ameliorations, and further testing in the field is needed to understand how these ameliorations might perform in actual restoration scenarios. Full article

The sagebrush steppe ecosystem plays a critical role in water cycling in arid and semiarid landscapes of the western United States; yet, there is limited information regarding individual sagebrush plant water uptake. We used the stem heat balance (SHB) method to measure transpiration in mountain big sagebrush (Artemisia tridentata subsp. vaseyana) plants in a semiarid rangeland ecosystem in central Oregon, Pacific Northwest Region, USA. We evaluated the relationship between sagebrush transpiration and environmental factors from July 2022 to May 2023 for two individual plants representative of the average sagebrush stand height and crown width at the study site; transpiration rates varied by plant and by season. This study encompassed one below-average (2022; 278 mm) and one above-average (2023; 414 mm) precipitation years. Study results showed that the average water use during the entire period of study was 2.1 L d⁻¹ for Plant 1 and 5.0 L d⁻¹ for Plant 2. During the dry year, maximum transpiration was observed during the summer (Plant 1 = 4.8 L d⁻¹; Plant 2 = 11.1 L d⁻¹). For the wet year, both plants showed maximum transpiration levels at the end of the recording period in mid-May (Plant 1 = 9.6 L d⁻¹; Plant 2 = 8.6 L d⁻¹). The highest seasonal transpiration of both plants occurred in summer (2.87 L d⁻¹), whereas the lowest transpiration was obtained in winter (0.21 L d⁻¹). For all seasons but winter, soil moisture (SM), soil temperature (ST), and vapor pressure deficit (VPD) variables generally showed positive correlations with transpiration. Transpiration rates decreased in the summer of 2022 as the surface soil gradually dried. The two plants’ most significant water uptake differences were obtained during the dry year. It is possible that the larger stem diameter of plant 2 may have contributed to its higher transpiration rates during times of limited water availability. The study results add to the understanding of water use by sagebrush and its potential impact on the water balance of cool-climate rangeland ecosystems. The findings also highlight the sensitivity of sagebrush to variations in seasonal soil moisture availability, soil temperature, and vapor pressure deficit. Future research should involve studying the combined effects of water use by various dominant vegetation species and its effects on the water budget at the watershed scale. Full article

Natural gas extraction is a critical driver of the economy in western North America. Ecological reclamation is important to ensure surface disturbance impacts associated with natural gas development are not permanent and to assist native biota. Previous studies in semi-arid natural gas fields within Sublette County, Wyoming, USA have shown insects respond favorably to 1–3-year-old well pads undergoing reclamation compared to older successional reference vegetation communities dominated by Wyoming big sagebrush (Artemisia tridentata spp. Wyomingensis). Here, we examined well pads which were initially seed 5, 8, 10, 11, and 12 years prior to our study. We used a free, image-based software called SamplePointv. 1.60 to quantify vegetation on these well pads and adjacent reference areas from cell phone camera photographs. Insects were collected with a sweep net and identified to the family and morphospecies level. Statistical analyses were conducted to compare both vegetation and insect communities between reclamation sites and their paired reference area. We found little statistical difference between vegetation communities across our study but found significantly more insect abundance on reclaimed well pads than reference areas in 3 of 5 years and significantly higher family and morphospecies richness on reclaimed well pads in 4 of 5 years. A total of 2036 individual insects representing 270 species from 71 families across 11 orders were identified across this study. A total of 1557 individuals (76.5%) were found on reclamation sites, whereas 479 (23.5%) were found in reference areas across the entire study. A total of 233 species (86.3% of total) were found on reclamation sites, whereas 121 species (44.8% of total) were found in reference areas across the entire study. A total of 67 families (94.4% of total) were found on reclamation sites, whereas 45 families (63.4% of total) were found in reference areas across the entire study. All 11 orders found in the study were found on reclamation sites, whereas 9 orders were found in reference areas across the entire study. Our results suggest reclamation of natural gas well pads within an old successional stand of sagebrush continues to support higher levels of insect biodiversity and abundance for at least 12 years. As insects are the most diverse group of animals on Earth and because they provide a wide array of ecosystem services, our findings suggest ecological reclamation plays an important role in returning biodiversity and ecosystem functionality to a semi-arid and old successional sagebrush–steppe ecosystem. Full article

Soil health is focused on intensively managed (IM) soils (often farmed soils), by-passing extensively managed (EM) soils (range lands, deserts, shrub lands, tundra). High economic value products are generated by IM systems. Many EM lands are of cultural, recreational, scenic, or scientific value. However, and despite the fact that they provide forage for domestic and wild animals, they are not always of high economic value. IM and EM soils are evaluated on the same health scales. The contention herein is all soils formed under soil state conditions under the absence of human interventions are inherently healthy. But a given soil has dynamic properties that determine its management as IM or EM. An EM sagebrush steppe soil may be deemed unhealthy as a result of low organic matter and short growing season. An IM grassland steppe soil is healthy as a result of high organic matter and a long growing season. The sagebrush soil, however, provides habitat for culturally important sage grouse. The grassland soil may provide, when plowed, habitat for economically important soybeans. Soil taxonomies can be used to establish inherent health of undisturbed soils. Determining a soil’s dynamic nature is a different construct. Here, four different sets of EM soils were evaluated to showcase their diversity, evaluate levels of health and display their often-unconventional dynamic characteristics. An argument is made that a soil’s health, an inherent condition, is not the same as its dynamic condition (potential to produce goods and services). Soil health changes are usually slowly driven by soil state factors but can be dramatically changed by humans. Otherwise, soil health can be viewed as a near constant ecosystem attribute. The dynamic nature of soils change according to needs placed by humans. EM soils may be healthy but lack attention since their dynamic nature is not traditional and often of low economic value. Evaluation of soil health and dynamic value on EM lands is often exacerbated by information absence. Strategies to circumvent this include sampling design, reference sites and standardized ways of EM soil health determination. A case is made that baselines of soil health can be taken from soil surveys, taxonomic names, and soil data from map units, where such information exists. Certified supplementary information is ambiguously available, but may be crucial. Outdoor living laboratories that feature inherent soil health and dynamic soil alternatives may help circumvent information voids. Full article

Biodiversity is threatened due to land-use change, overexploitation, pollution, and anthropogenic climate change, altering ecosystem functioning around the globe. Protecting areas rich in biodiversity is often difficult without fully understanding and mapping species’ ecological niche requirements. As a result, the umbrella species concept is often applied, whereby conservation of a surrogate species is used to indirectly protect species that occupy similar ecological communities. One such species is the greater sage-grouse (Centrocercus urophasianus), which has been used as an umbrella to conserve other species within the sagebrush (Artemisia spp.) ecosystem. Sagebrush-steppe ecosystems within the United States have experienced drastic loss, fragmentation, and degradation of remaining habitat, threatening sagebrush-dependent fauna, resulting in west-wide conservation efforts to protect sage-grouse habitats, and presumably other sagebrush wildlife. We evaluated the effectiveness of the greater sage-grouse umbrella to conserve biodiversity using data-driven spatial occupancy and abundance models for seven sagebrush-dependent (obligate or associated) species across the greater Wyoming Basins Ecoregional Assessment (WBEA) area (345,300 km²) and assessed overlap with predicted sage-grouse occurrence. Predicted sage-grouse habitat from empirical models only partially (39–58%) captured habitats identified by predicted occurrence models for three sagebrush-obligate songbirds and 60% of biodiversity hotspots (richness of 4–6 species). Sage-grouse priority areas for conservation only captured 59% of model-predicted sage-grouse habitat, and only slightly fewer (56%) biodiversity hotspots. We suggest that the greater sage-grouse habitats may be partially effective as an umbrella for the conservation of sagebrush-dependent species within the sagebrush biome, and management actions aiming to conserve biodiversity should directly consider the explicit mapping of resource requirements for other taxonomic groups. Full article

Agriculture generates ~83% of total US ammonia (NH₃) emissions, potentially adversely impacting sensitive ecosystems through wet and dry deposition. Regions with intense livestock production, such as the dairy region of south-central Idaho, generate hotspots of NH₃ emissions. Our objective was to measure the spatial and temporal variability of NH₃ across this region and estimate its dry deposition. Ambient NH₃ was measured using diffusive passive samplers at 8 sites in two transects across the region from 2018–2020. NH₃ fluxes were estimated using the Surface Tiled Aerosol and Gaseous Exchange (STAGE) model. Peak NH₃ concentrations were 4–5 times greater at a high-density dairy site compared to mixed agriculture/dairy or agricultural sites, and 26 times greater than non-agricultural sites with prominent seasonal trends driven by temperature. Annual estimated dry deposition rates in areas of intensive dairy production can approach 45 kg N ha⁻¹ y⁻¹, compared to <1 kg N ha⁻¹ y⁻¹ in natural landscapes. Our results suggest that the natural sagebrush steppe landscapes interspersed within and surrounding agricultural areas in southern Idaho receive NH₃ dry deposition rates within and above the range of nitrogen critical loads for North American deserts. Finally, our results highlight a need for improved understanding of the role of soil processes in NH₃ dry deposition to arid and sparsely vegetated natural ecosystems across the western US. Full article

(1) Background: Satellite monitoring of fire effects is widespread, but often satellite-derived values are considered without respect to the characteristic severity of fires in different vegetation types or fire areas. Particularly in regions with discontinuous vegetation or narrowly distributed vegetation types, such as the state of Utah, USA, specific characterization of satellite-derived fire sensitivity by vegetation and fire size may improve both pre-fire and post-fire management activities. (2) Methods: We analyzed the 775 medium-sized (40 ha ≤ area < 400 ha) and 697 large (≥400 ha) wildfires that occurred in Utah from 1984 to 2022 and assessed burn severity for all vegetation types using the differenced Normalized Burn Ratio. (3) Results: Between 1984–2021, Utah annually experienced an average of 38 fires ≥ 40 ha that burned an annual average of 58,242 ha with a median dNBR of 165. Fire was heavily influenced by sagebrush and shrubland vegetation types, as these constituted 50.2% (17% SD) of area burned, a proportion which was relatively consistent (18% to 79% yr⁻¹). Medium-sized fires had higher mean severity than large fires in non-forested vegetation types, but forested vegetation types showed the reverse. Between 1985 and 2021, the total area burned in fires ≥ 40 ha in Utah became more concentrated in a smaller number of large fires. (4) Conclusions: In Utah, characteristic fire severity differs both among vegetation types and fire sizes. Fire activity in the recent past may serve as an informative baseline for future fire, although the long period of fire suppression in the 20th century suggests that future fire may be more active. Fire managers planning prescribed fires < 400 ha in forests may find the data from medium-sized fires more indicative of expected behavior than statewide averages or vegetation type averages, both of which are weighted to large fires. Full article

The establishment of Artemisia tridentata, a keystone species of the sagebrush steppe, is often limited by summer drought. Symbioses with arbuscular mycorrhizal fungi (AMF) can help plants to cope with drought. We investigated this possible effect on A. tridentata seedlings inoculated with native AMF and exposed to drought in greenhouse and field settings. In greenhouse experiments, AMF colonization increased intrinsic water use efficiency under water stress and delayed the decrease in photosynthesis caused by drought, or this decrease occurred at a lower soil water content. In the field, we evaluated the effect of AMF inoculation on colonization, leaf water potential, survival, and inflorescence development. Inoculation increased AMF colonization, and the seedlings experienced water stress, as evidenced by water potentials between −2 and −4 MPa and reduced stomatal conductance. However, survival remained high, and no differences in water potentials or survival occurred between treatments. Only the percentage of plants with inflorescence was higher in inoculated than non-inoculated seedlings. Overall, the greenhouse results support that AMF colonization enhances drought tolerance in A. tridentata seedlings. Yet, the significance of these results in increasing survival in nature remains to be tested under more severe drought than the plants experienced in our field experiment. Full article

The sagebrush steppe has presented increasing levels of degradation. The addition of arbuscular mycorrhizal fungi (AMF) and biochar have been suggested to restore ecosystems. However, little is known about their effects on sagebrush steppe plants. We tested three sources of AMF inoculum: soil from a disturbed site (Inoculum A), soil from an undisturbed site (Inoculum B), and commercial inoculum (Inoculum C), all with and without biochar, to test if they could mediate growth of Pseudoroegneria spicata (native perennial), Taeniatherum caput-medusae (early seral; exotic annual) and Ventenata dubia (early seral; exotic annual) under greenhouse conditions. We measured AMF colonization and biomass. We hypothesized that the plant species would be differently affected by the inoculum types. The colonization of T. caput-medusae and V. dubia was greatest when inoculated with Inoculum A (38.8% and 19.6%). In contrast, the colonization of P. spicata was greatest with Inoculum B and Inoculum C (32.1% and 32.2). Biochar decreased biomass production but increased colonization with Inoculum A for P. spicata and V. dubia and with Inoculum C for T. caput-medusae. This study reveals the response of early and late seral sagebrush steppe grass species to contrasting sources of AMF and suggests that late seral plant species respond better to late seral inocula. Full article

Western juniper was often historically restricted to fire refugia such as rocky outcrops but has since Euro-American settlement expanded into areas previously dominated by sagebrush steppe. Wildfires in developed woodlands have been rare. In 2007, the Tongue-Crutcher Wildland Fire burned 18,890 ha in southwestern Idaho along a woodland development gradient, providing unique research opportunities. To assess fire effects on vascular plants, field data were collected in 2012/2013 and 2019/2020. Species richness was uniform along the sere, while species diversity declined in late woodland stages attributed to juniper dominance. The greatest changes in species composition following fire occurred in later woodland development phases. Herbaceous vegetation increased following fire, but sagebrush cover was still lower in burned plots 12–13 years post-fire. Many stands dominated by juniper pre-fire became dominated by snowbrush ceanothus post-fire. Juniper seedlings were observed post-fire, indicating that juniper will reoccupy the area. Our research demonstrates resilience to fire and resistance to annual grasses particularly in early successional stages, which provides opportunities for fire use as a management tool on cool and moist ecological sites. Loss of old-growth juniper to wildfire underlines the importance of maintaining and provisioning for future development of some old growth on the landscape given century-long recovery times. Full article

The genus Artemisia includes several keystone shrub species that dominate the North American sagebrush steppe. Their growth, survival, and establishment are negatively affected by exotic invasive grasses such as Taeniatherum caput-medusae. While the outcomes of symbiotic relationships between Artemisia spp. and arbuscular mycorrhizal fungi (AMF) are ambiguous, the benefits of ameliorated nutrient and drought stress may be cryptic and better revealed under competition. We evaluated the effects of a commercial AMF inoculum on ameliorating biotic (competition with T. caput-medusae) and abiotic (drought) stress of Artemisia tridentata ssp. wyomingensis, Artemisia arbuscula, and Artemisia nova when grown in sterile and microbially active field soil. Stress amelioration was measured as an increase in biomass production and nutrient acquisition. Mycorrhizal colonization of roots was lower in Artemisia plants grown in competition, while T. caput-medusae colonization was higher in plants with greater moisture. Both types of stress negatively affected plant biomass. Commercial AMF inoculation did not increase biomass. Colonization from field soil increased average phosphorous concentration under drought for A. tridentata ssp. wyomingensis by 36% and A. nova by 125%. While commercial inoculum and live soil led to AMF colonization of T. caput-medusae, only the commercial inoculum increased average phosphorus uptake by 71%. Full article

Biotic interactions can affect a plant’s ability to withstand drought. Such an effect may impact the restoration of the imperiled western North American sagebrush steppe, where seedlings are exposed to summer drought. This study investigated the impact of herbivory on seedlings’ drought tolerance for a keystone species in this steppe, the shrub Artemisia tridentata. Herbivory effects were investigated in two field experiments where seedlings were without tree protectors or within plastic or metal-mesh tree protectors. Treatment effects were statistically evaluated on herbivory, survival, leaf water potential, and inflorescence development. Herbivory occurrence was 80% higher in seedlings without protectors. This damage occurred in early spring and was likely caused by ground squirrels. Most plants recovered, but herbivory was associated with higher mortality during the summer when seedlings experienced water potentials between −2.5 and −7 MPa. However, there were no differences in water potential between treatments, suggesting that the browsed plants were less tolerant of the low water potentials experienced. Twenty months after outplanting, the survival of plants without protectors was 40 to 60% lower than those with protectors. The percentage of live plants developing inflorescences was approximately threefold higher in plants with protectors. Overall, spring herbivory amplified susceptibility to drought and delayed reproductive development. Full article