Low Sagebrush Research Articles

Fuel treatment response groups for fire-prone sagebrush landscapes

BackgroundSagebrush shrublands in the Great Basin, USA, are experiencing widespread increases in wildfire size and area burned resulting in new policies and funding to implement fuel treatments. However, we lack the spatial data needed to optimize the types and locations of fuel treatments across large landscapes and mitigate fire risk. To address this, we developed treatment response groups (TRGs)—sagebrush and pinyon-juniper vegetation associations that differ in resilience to fire and resistance to annual grass invasion (R&R) and thus responses to fuel treatments.ResultsWe developed spatial layers of the dominant sagebrush associations by overlaying LANDFIRE Existing Vegetation Type, Biophysical Setting, and Mapping Zone, extracting vegetation plot data from the LANDFIRE 2016 LF Reference Database for each combination, and identifying associated sagebrush, grass, shrub, and tree species. We derived spatial layers of pinyon-juniper (PJ) cover and expansion phase within the sagebrush associations from the Rangeland Analysis Platform and identified persistent PJ woodlands from the LANDFIRE Biophysical Setting. TRGs were created by overlaying dominant sagebrush associations, with and without PJ expansion, and new indicators of resilience and resistance. We assigned appropriate woody fuel treatments to the TRGs based on prior research on treatment responses. The potential area to receive woody fuel treatments was constrained to 52,940 km2 (18.4%) of the dominant sagebrush associations (272,501 km2) largely because of extensive areas of low R&R (68.9%), which respond poorly and were not assigned treatments. Prescribed fire was assigned to big sagebrush associations with moderate or higher resilience and moderately low or higher resistance (14.2%) due to higher productivity, fuels, and recovery potential. Mechanical treatments were assigned to big sagebrush associations with moderately low resilience and to low, black, and mixed low sagebrush associations with moderately low or higher R&R (4.2%) due to lower productivity, fuels, and recovery potential. Persistent PJ woodlands represent high value resources and were not assigned treatments (9%).ConclusionsMapped TRGs can help identify the dominant sagebrush associations and determine appropriate fuel treatments at intermediate scales and provide the basis for quantitative wildfire risk assessments and outcome-based scenario planning to prioritize fuel treatment investments at large landscape scales.

Drought and Competition Mediate Mycorrhizal Colonization, Growth Rate, and Nutrient Uptake in Three Artemisia Species.

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%.

Maladaptive nest‐site selection and reduced nest survival in female sage‐grouse following wildfire

AbstractIncreased wildfire frequency and associated replacement of sagebrush (Artemisia spp.) with invasive annual grasses contribute to declines of greater sage‐grouse (Centrocercus urophasianus; hereafter, sage‐grouse) populations across the Great Basin. However, little is known about wildfire effects on sage‐grouse nest‐site selection and nest survival, which can influence population persistence. The primary objective of this study was to evaluate the effects of the Rush Fire on sage‐grouse nest survival using before (2007–2009) and after (2015–2018) data collected from a population of sage‐grouse occupying the border of northeastern California and northwestern Nevada. We employed a before–after–control–impact (BACI) experimental design to account for spatiotemporal heterogeneity in the system and to derive estimates of relative change in survival parameters. Sage‐grouse nest survival decreased after the Rush Fire but decreased more in the burned area relative to the unburned area. Although female sage‐grouse continued to occupy burned areas, nest survival was reduced from 52% to 19%. Using a BACI ratio approach we found that nest survival decreased approximately 51% in the burned area, relative to the unburned area, following wildfire. Habitat analyses were restricted to the postfire period and found that female sage‐grouse that nested within unburned areas selected for wider nesting substrate, taller perennial grass height, and greater low sagebrush canopy cover. Conversely, female sage‐grouse that nested in burned areas used shorter sagebrush canopy cover than what was available across the entire study area but showed stronger selection for perennial grass height than their unburned counterparts. Strong nest‐site fidelity in sage‐grouse may explain the continued use of suboptimal habitat in wildfire‐altered landscapes, resulting in a reproductive cost, and overall reproduction well below replacement rate. Results suggest that fire suppression or rapid postfire habitat restoration, especially within nesting habitat, may be essential to conserving robust sage‐grouse populations into the future.

Temporal mismatch in space use by a sagebrush obligate species after large‐scale wildfire

AbstractThe increase in size and frequency of wildfires in sagebrush steppe ecosystems has significant impacts on sagebrush obligate species. We modeled seasonal habitat use by female greater sage‐grouse (Centrocercus urophasianus) in the Trout Creek Mountains of Oregon and Nevada, USA, to identify landscape characteristics that influenced sage‐grouse habitat selection and to create predictive surfaces of seasonal use 1 and 7 years postfire. We developed three resource selection function models using GPS location data from 2013 to 2019 for three biologically distinct seasons (breeding, n = 149 individuals: 8 March–12 June; summer, n = 140 individuals: 13 June–20 October; and winter, n = 94 individuals: 21 October–7 March). For all seasons, by the fourth or fifth year postfire, sage‐grouse selected for unburned patches more than all other burn severity patches and the use of unburned areas in comparison with burned areas increased through time. During the breeding season, sage‐grouse selected for low‐sagebrush (Artemisia arbuscula)‐dominated ecosystems and areas with low biomass (normalized difference vegetation index). During summer, sage‐grouse selected for areas with higher annual and perennial grasses and forb cover, and areas that had higher biomass. During winter, sage‐grouse selected for areas of intact sagebrush on less rugged terrain. For the winter and breeding season, there was a positive linear relationship between annual grasses and forb cover through time. Seven years postfire (2019), the area predicted to have a high probability of use in each seasonal range decreased (breeding: 16.4%; summer: 12.2%; and winter: 4.2%), while the area predicted to have low or low‐medium probability of use increased (breeding: 14.5%; summer: 22.5%; and winter: 22.8%) when compared to the first year following the wildfire (2013). Our results demonstrated a 4‐ to 5‐year time lag before female sage‐grouse adapted to a disturbed landscape began avoiding burned areas more than intact, unburned habitats. This mismatch in ecological response may imply declines in habitat availability for sage‐grouse and may destabilize population vital rates. Spatially explicit models can aid in identifying priority areas for restoration efforts and conservation actions to mitigate the impacts of future disturbances.

Early Succession Following Prescribed Fire in Low Sagebrush (Artemisia arbuscula var. Arbuscula) Steppe

We evaluated plant community succession following prescribed fire on Artemisia arbuscula var. arbuscula (Nutt.) McMinn (low sagebrush) steppe in southeastern Oregon. Treatments were “prescribed burned” (burn; fall 2012) and “unburned” (control) A. arbuscula steppe, and the study design was a randomized complete block with 4 replicates per treatment. Herbaceous yield and vegetation canopy cover and density were compared between treatments (2012–2020). Fire practically eliminated A. arbuscula and there was no recruitment of new plants in the first 8 years after burning. Herbaceous yield in the burn treatment was about double the control for most of the postfire period. Native perennial grasses and forbs constituted 94% to 96% and Bromus tectorum L. (cheatgrass) 0.2% to 2% of total herbaceous yield in the control. In the burn treatment, perennial grasses and forbs constituted 83% to 87%, native annual forbs 2% to 5%, and B. tectorum 3% to 9% of total herbaceous yield. Despite an increase in B. tectorum, the burned A. arbuscula sites were dominated by herbaceous perennial grasses and forbs and exhibited high levels of resilience and resistance. After prescribed fire, for the study sites and comparable A. arbuscula associations, weed control or seeding are not necessary to recover the native herbaceous community. However, the results in our study are for low-severity prescribed fire in intact A. arbuscula plant communities. Higher-severity fire, as might occur with wildfire, and in A. arbuscula communities having greater prefire invasive weed composition should not be assumed to develop similarly high levels of community resilience and resistance.

Drought and shrub cover differentially affect seed bank composition within two sagebrush steppe communities

Soil seed banks are critical biodiversity repositories for dryland plant communities. Understanding how environmental factors alter seed bank composition provides valuable information on ecological processes within a community and can be useful for creating land management strategies. We assessed seed bank response to drought and microsite within an Artemisia arbuscula dominated community and a directly adjacent (∼60m apart) A. cana dominated community, and characterized the similarity between these two seed banks and the corresponding aboveground vegetation. We found that drought increased exotic grass seed density and decreased seed species diversity and evenness within the A. arbuscula community, whereas shrub microsites enhanced seed species diversity and native forb seed density. In contrast, there were only minor drought effects within the A. cana community. Within both plant communities, there was low similarity between the seed bank and existing vegetation (<28%), and both seed banks were comprised of over 50% exotic annual grass seeds. Our study suggests that seed banks of drylands similar to A. arbuscula dominated plant communities (with heterogenous landscapes and low soil moisture availability) may experience more drought induced impacts than adjacent sagebrush communities, and highlights the role of shrub canopies as beneficial microsites for seeds in some drylands.

Using an Ultraviolet Light Test to Improve Sagebrush Identification and Predict Forage Quality for Wildlife

Sagebrush identification can be improved by using a relatively easy ultraviolet (UV) light test on specimens. Sagebrush produces a variety of water-soluble polyphenols called coumarins, which fluoresce a blue color under UV light and can help differentiate species, subspecies, and hybrids. We tested 16 different sagebrush taxa (including species and subspecies) from herbarium specimens and found 3 taxa (low sagebrush, Artemisia arbuscula; Wyoming sagebrush, A. tridentata wyomingensis; and basin sagebrush, A. t. tridentata) that were often misidentified. We show that the UV light test can greatly improve identification of these species. Moreover, given that the UV+ chemicals that discriminate taxa are also considered an indirect biomarker of sagebrush palatability for some herbivores, the UV light test can be used to predict forage quality for threatened species like sage-grouse (Centrocercus spp.) and pygmy rabbits (Brachylagus idahoensis). Collecting voucher specimens of sagebrush at wildlife study sites and comparing their UV intensity to historical herbarium specimens could help identify both current and changing availability of palatable sagebrush for wildlife. We found that even herbarium specimens >80 years old still fluoresce under UV light.

Use of Plant Growth Regulators to Expand Sagebrush Germination Rates for Restoration Efforts

Seed germination during unhospitable environmental conditions can be a major barrier to direct seeding efforts in dryland systems. In the sagebrush steppe, Wyoming big sagebrush and low sagebrush are important shrub species used in restoration; however, seeding success is highly sporadic due to interannual and intraseasonal weather variability. It may be possible to improve restoration success by expanding the period of seed germination to increase the chances some seeds will germinate within a window that is favorable for plant establishment. Our objective was to determine if we could expand the period of germination using plant growth regulators (PGRs) applied in a conglomerated seed coating to Wyoming big sagebrush and low sagebrush. The seed of each species was 1) left untreated; 2) conglomerated; 3) conglomerated and treated with two concentrations of a germination inhibitor, abscisic acid (ABA); or 4) conglomerated and treated with two different germination promoters, gibberellic acid (GA3) and 1-aminocyclopropane carboxylic acid (ACC) (6 treatments total). Seeds were incubated in a loam soil at five constant temperatures (5−25°C) for approximately 3 mo. Results indicate that seed treatments with PGRs can delay or accelerate germination. For example, at 5°C, which is the temperature most similar to when the seeds germinate in the field, ABA delayed the time for 50% of the seeds to germinate by a maximum of 28 d and 38 d and the germination promoters decreased this time by 9 d and 11 d for Wyoming big sagebrush and low sagebrush, respectively. Field studies are now needed to determine if the bet-hedging strategy developed in this study will increase the likelihood of seeding success. Although our study focused on sagebrush, there is merit to evaluate the use of PGRs on other species, particularly where seed is being sown in highly variable environments.

Accounting for aboveground carbon storage in shrubland and woodland ecosystems in the Great Basin

AbstractImproving the accuracy of carbon accounting in terrestrial ecosystems is critical for understanding carbon fluxes associated with land cover change, with significant implications for global carbon cycling and climate change. Semi‐arid ecosystems account for an estimated 45% of global terrestrial ecosystem area and are in many locations experiencing high degrees of degradation. However, aboveground carbon accounting has largely focused on tropical and forested ecosystems, while drylands have been relatively neglected. Here, we used a combination of field estimates, remotely sensed data, and existing land cover maps to create a spatially explicit estimate of aboveground carbon storage within the Great Basin, a semi‐arid region of the western United States encompassing 643,500 km2 of shrubland and woodland vegetation. We classified the region into seven distinct land cover categories: pinyon‐juniper woodland, sagebrush steppe, salt desert shrub, low sagebrush, forest, non‐forest, and other/excluded, each with an associated carbon estimate. Aboveground carbon estimates for pinyon‐juniper woodland were continuous values based on tree canopy cover. Carbon estimates for other land cover categories were based on a mean value for the land cover type. The Great Basin ecosystems contain an estimated 295.4 Tg in aboveground carbon, which is almost double the previous estimates that only accounted for forested ecosystems in the same area. Aboveground carbon was disproportionately stored in pinyon‐juniper woodland (43.7% carbon, 16.9% land area), while the shrubland systems accounted for roughly half of the total land area (49.1%) and one‐third of the total carbon. Our results emphasize the importance of distinguishing and accounting for the distinctive contributions of shrubland and woodland ecosystems when creating carbon storage estimates for dryland regions.

Seasonal Wetness, Soil Organic Carbon, and Fire Influence Soil Hydrological Properties and Water Repellency in a Sagebrush‐Steppe Ecosystem

AbstractPrescribed fire is an important tool for rangeland management in sage‐steppe ecosystems, yet the long‐term effects of this practice on soil hydraulic properties are not well known. We explore interactions among site geomorphology, soil organic carbon (SOC) soil N, soil water repellency (SWR), and plant community type on infiltration properties before fire and 8 years thereafter in a semiarid research watershed. The objective was to assess the sustainability of rangeland burning in sage‐steppe ecosystems. Many types of measurements were made in three plant communities to identify how differences in soil hydraulic properties are related to differences in plant cover and soil texture and to determine relationships among SOC, SWR, soil water contact angle, and infiltration properties. Measurements were made on transects in burned and unburned catchments. We found that severity and occurrence of surface SWR were substantially reduced 8 years after a fire within the area originally covered with mountain big sagebrush, where the fire intensity was greatest. Surface SWR was lowest in the sparsely vegetated low sagebrush, where SOC was also lowest. Unsaturated hydraulic conductivity (Kh) increased in each vegetation type over the 8‐year period after burning and was not directly related to SWR. Spatial variability in Kh was primarily controlled by soil texture, whereas differences in sorptivity (S) were controlled by SWR and aridity. SOC is not well correlated to soil surface SWR. The decadal scale changes in Kh and associations between S and site characteristics indicate forms of resilience to fire across a moisture gradient.

Climatic Influences on Establishment Pulses of Four Artemisia Species in Nevada

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.

Hydrologic response and recovery to prescribed fire and vegetation removal in a small rangeland catchment

AbstractPrescribed fire can be used to return wild lands to their natural fire cycle, control invasive weeds, and reduce fuel loads, but there are gaps in the understanding of post‐disturbance responses of vegetation and hydrology. The impact of a prescribed fire and subsequent aspen cutting on evapotranspiration (ET) and streamflow was assessed for the Upper Sheep Creek catchment, a 26‐ha headwater catchment dominated by low sagebrush, mountain big sagebrush, and aspen within the Reynolds Creek Experimental Watershed. The 2007 prescribed fire consumed 100% of the mountain big sagebrush and approximately 21% of the low sagebrush. The aspen, which were mostly untouched by the fire, were cut in the fall of 2008. Post‐disturbance ET and vegetation recovery were related to the loss of rooting depth. ET recovered within 2 years on the low sagebrush area with limited rooting depth, while that on the deeper‐rooted mountain big sagebrush area took 4 years to recover. ET from the aspen trees, which can sprout from existing roots, recovered within 2 years. The influence of vegetation disturbance on streamflow was assessed using both empirical time trend analysis and process‐based modelling. Although both approaches suggested approximately a 20% increase in streamflow during the 6 years post‐disturbance, results from the empirical time trend analysis were marginally significant (p = 0·055), while those from the process‐based modelling were not statistically significant. Marginal streamflow response can be attributed to rapid post‐disturbance recovery of the aspen where most of the streamflow originates. Published 2016. This article is a U.S. Government work and is in the public domain in the USA

Surface water input from snowmelt and rain throughfall in western juniper: potential impacts of climate change and shifts in semi‐arid vegetation

AbstractIn the western USA, shifts from snow to rain precipitation regimes and increases in western juniper cover in shrub‐dominated landscapes can alter surface water input via changes in snowmelt and throughfall. To better understand how shifts in both precipitation and semi‐arid vegetation cover alter above‐ground hydrological processes, we assessed how rain interception differs between snow and rain surface water input; how western juniper alters snowpack dynamics; and how these above‐ground processes differ across western juniper, mountain big sagebrush and low sagebrush plant communities. We collected continuous surface water input with four large lysimeters, interspace and below‐canopy snow depth data and conducted periodic snow surveys for two consecutive water years (2013 and 2014). The ratio of interspace to below‐canopy surface water input was greater for snow relative to rain events, averaging 79.4% and 54.8%, respectively. The greater surface water input ratio for snow is in part due to increased deposition of redistributed snow under the canopy. We simulated above‐ground energy and water fluxes in western juniper, low sagebrush and mountain big sagebrush for two 8‐year periods under current and projected mid‐21st century warmer temperatures with the Simultaneous Heat and Water (SHAW) model. Juniper compared with low and mountain sagebrush reduced surface water input by an average of 138 mm or 24% of the total site water budget. Conversely, warming temperatures reduced surface water input by only an average of 14 mm across the three vegetation types. The future (warmer) simulations resulted in earlier snow disappearance and surface water input by 51 and 45 days, respectively, across juniper, low sagebrush and mountain sagebrush. Information from this study can help land managers in the sagebrush steppe understand how both shifts in climate and semi‐arid vegetation will alter fundamental hydrological processes. Copyright © 2016 John Wiley &amp; Sons, Ltd.

Spatial Analysis of Greater Sage-grouse Habitat Use in Relation to Landscape Level Habitat Structure

Greater sage-grouse (GSG; Centrocercus urophasianus) selectively utilize portions of sagebrush and sagebrush associated habitats within broad and heterogeneous landscapes. Until recently, sage-grouse research has generally focused on fine-scale vegetation structure and composition and less on landscape-scale habitat requirements. Insufficient information at broad scales limits a manager’s ability to interpret and predict habitat use patterns, assess habitat suitability, and target areas for conservation and ecological rehabilitation. We identified environmental attributes associated with GSG habitat use at broad spatial scales. In 2006, we captured 50 GSG, radio-collared each bird, and tracked each bird’s position within a 31,416 ha study area in central Oregon, USA. We monitored birds year-long between March 2006 and March 2008 across the study area. Each time a bird was located, we collected a coordinate position at the point where it was observed. We generated spatially explicit predictor variables in a Geographic Information System to quantify the association between landscape structure and GSG occurrence. Predictor variables included elevation, slope, aspect, curvature, solar radiation, landscape ruggedness, orientation, distance from roads, distance from leks, distance from mesic habitats, and cover type. We used spatial modeling (Maximum Entropy) to 1) develop predictive models of GSG seasonal resource use, 2) generate probability maps for visual assessment, and 3) characterize response curves associated with GSG habitat preference based on individual landscape predictor variables. Results indicate that during the breeding season GSG will use big sagebrush, low sagebrush or complexes of low and mountain big sagebrush cover types. During the summer season, GSG use low sagebrush, mountain big sagebrush, and mesic areas. Additionally, summer season use areas include higher elevation sites within or in close proximity to habitats that sustain succulent forbs throughout most of the growing season. Maps of modeled data identify spatially explicit areas of preferred habitat and predicted bird use patterns. This information can help managers identify and protect important GSG habitat across heterogeneous landscapes.

Insights into transcriptomes of big and low sagebrush.

We report the sequencing and assembly of three transcriptomes from Big (Artemisia tridentata ssp. wyomingensis and A. tridentata ssp. tridentata) and Low (A. arbuscula ssp. arbuscula) sagebrush. The sequence reads are available in the Sequence Read Archive of NCBI. We demonstrate the utilities of these transcriptomes for gene discovery and phylogenomic analysis. An assembly of 61,883 transcripts followed by transcript identification by the program TRAPID revealed 16 transcripts directly related to terpene synthases, proteins critical to the production of multiple secondary metabolites in sagebrush. A putative terpene synthase was identified in two of our sagebrush samples. Using paralogs with synonymous mutations we reconstructed an evolutionary time line of ancient genome duplications. By applying a constant mutation rate to the data we estimate that these three ancient duplications occurred about 18, 34 and 60 million years ago. These transcriptomes offer a foundation for future studies of sagebrush, including inferences in chemical defense and the identification of species and subspecies of sagebrush for restoration and preservation of the threatened sage-grouse.

Quantifying restoration effectiveness using multi‐scale habitat models: implications for sage‐grouse in the Great Basin

A recurrent challenge in the conservation of wide‐ranging, imperiled species is understanding which habitats to protect and whether we are capable of restoring degraded landscapes. For Greater Sage‐grouse (Centrocercus urophasianus), a species of conservation concern in the western United States, we approached this problem by developing multi‐scale empirical models of occupancy in 211 randomly located plots within a 40 million ha portion of the species' range. We then used these models to predict sage‐grouse habitat quality at 826 plots associated with 101 post‐wildfire seeding projects implemented from 1990 to 2003. We also compared conditions at restoration sites to published habitat guidelines. Sage‐grouse occupancy was positively related to plot‐ and landscape‐level dwarf sagebrush (Artemisia arbuscula, A. nova, A. tripartita) and big sagebrush steppe prevalence, and negatively associated with non‐native plants and human development. The predicted probability of sage‐grouse occupancy at treated plots was low on average (0.09) and not substantially different from burned areas that had not been treated. Restoration sites with quality habitat tended to occur at higher elevation locations with low annual temperatures, high spring precipitation, and high plant diversity. Of 313 plots seeded after fire, none met all sagebrush guidelines for breeding habitats, but approximately 50% met understory guidelines, particularly for perennial grasses. This pattern was similar for summer habitat. Less than 2% of treated plots met winter habitat guidelines. Restoration actions did not increase the probability of burned areas meeting most guideline criteria. The probability of meeting guidelines was influenced by a latitudinal gradient, climate, and topography. Our results suggest that sage‐grouse are relatively unlikely to use many burned areas within 20 years of fire, regardless of treatment. Understory habitat conditions are more likely to be adequate than overstory conditions, but in most climates, establishing forbs and reducing cheatgrass dominance is unlikely. Reestablishing sagebrush cover will require more than 20 years using past restoration methods. Given current fire frequencies and restoration capabilities, protection of landscapes containing a mix of dwarf sagebrush and big sagebrush steppe, minimal human development, and low non‐native plant cover may provide the best opportunity for conservation of sage‐grouse habitats.

Relationship between sagebrush species and structural characteristics and Landsat Thematic Mapper data

Questions Do the spectral patterns recorded by Landsat Thematic Mapper (TM) for various sagebrush species differ from each other? Could ancillary data derived from topographic variables (elevation, slope and aspect) strengthen the relationship between sagebrush and spectral characteristics? Location Rawlins, Wyoming, USA. Methods Field data on sagebrush species and structural characteristics collected in 2005 were regressed against spectral values and transformed indices derived from Landsat TM data. Step-wise regression methods were used to build (1) a combined model that ignored species and physical differences in sagebrush, and (2) four different models that took those differences in account. Parsimonious models were selected with significant independent variables that accounted for the largest amount of the ground-measured variation in cover. Results In the combined model, a subset of Landsat bands and topographic values accounted for 65% (P < 0.001) of variance in sagebrush canopy cover. However, when separate regression models were fitted based on species type (big and low sagebrush) and height (for big sagebrush only), Landsat data accounted for 71–85% (P < 0.001) of the ground measured variance. Conclusions Spectral patterns of sagebrush species and their physical characteristics were distinguishable with Landsat TM data. Transformed indices derived from Landsat data accounted for more variance than the original spectral bands. Future research should focus on testing the relationship between Landsat TM data and sites where sagebrush is present with other vegetation to facilitate landscape and regional mapping of changing sagebrush ecosystems.

Habitat Selection by Greater Sage-Grouse During Winter in Southeastern Oregon

The distribution and geographic range of Greater Sage-Grouse (Centrocercus urophasianus) have been reduced by 56% since European settlement. Although loss and fragmentation of sagebrush (Artemisia spp.) habitats have been cited as the primary causes for the decline of the species, degradation of existing habitat also has been considered an important factor. Guidelines for protection and management of breeding and winter habitat have been developed for land managers, but winter habitat use has not been thoroughly described throughout the species' range, particularly for the western portion of its range in Oregon. We examined vegetation-type selection and use by Greater Sage-Grouse during winter (Nov–Feb) at 3 study areas in southeastern Oregon (1989–1992). Elevation gradients and vegetative communities differed among these 3 areas. Our objective was to examine the geographic variation in the selection and use of various vegetation types during winter, when sage-grouse distributions may be most restricted. We described differences in vegetation structure at the microhabitat scale among 3 areas and differences in vegetation-type selection at the macrohabitat scale. We found that the use of mixed sagebrush (basin big sagebrush [Artemisia tridentata tridentata]) and other shrubby vegetation types by sage-grouse was greater than expected at all 3 study areas. At the low- and high-elevation study areas, low sagebrush (Artemisia longiloba) vegetation types were selected more often than expected at random, which was contrary to our original hypotheses. Basin big sagebrush vegetation types were used in proportion to their availability at the 2 low-elevation study areas, and big sagebrush steppe was used less than available (avoided) at the low-elevation areas; these results were contrary to our original predictions. Such differences in selection among the study areas in southeastern Oregon create additional challenges for land managers, who are charged with managing habitats for sage-grouse use during autumn and winter in this portion of the species' geographic range.

Greater Sage-Grouse Movements and Habitat use during Winter in Central Oregon

Greater Sage-Grouse (Centrocercus urophasianus) depend on sagebrush habitat for food and cover during winter, yet few sage-grouse winter ecology studies have been conducted. During January and February 2007, we monitored 22 radio-collared sage-grouse (7 females and 15 males) in central Oregon to characterize winter habitat use and movement patterns. We estimated distances traveled between locations on a weekly basis and quantified habitat characteristics at locations used by male and female sage-grouse. The birds we collared moved extensively across the landscape, using approximately 1480 km2. Sagebrush canopy height in sites used by sage-grouse varied from 0.25 to 0.75 m, with females tending to be found in sites with taller sagebrush and less foliar cover than in sites where we found males. The difference in foliar cover between sexes was related to a seasonal change in habitat use: 4 females found in little sagebrush (Artemisia arbuscula) in January and early February were no longer located nor found foraging in little sagebrush after 15 February. Also, by this date, most male sage-grouse had stopped using big sagebrush (Artemisia tridentata) as they migrated to leks. Sage-grouse mortality rates were low during our study, which may be attributed to the study area receiving half the long-term average amount of snow. The large area over which sage-grouse moved during winter indicates that conservation of Greater Sage-Grouse may require preservation of sagebrush at landscape scales (thousands of square kilometers).

LiDAR-Based Classification of Sagebrush Community Types

Abstract Sagebrush ( Artemisia spp.) communities constitute the largest temperate semidesert in North America and provide important rangelands for livestock and habitat for wildlife. Remote sensing methods might provide an efficient method to monitor sagebrush communities. This study used airborne LiDAR and field data to measure vegetation heights in five different community types at the Reynolds Creek Experimental Watershed, southwestern Idaho: herbaceous-dominated, low sagebrush ( Artemisia arbuscula ) –dominated, big sagebrush ( Artemisia tridentata spp.) –dominated, bitterbrush ( Purshia tridentata ) -dominated, and other vegetation community types. The objectives were 1) to quantify the correlation between field-measured and airborne LiDAR-derived shrub heights, and 2) to determine if airborne LiDAR-derived mean vegetation heights can be used to classify the five community types. The dominant vegetation type and vegetation heights were measured in 3 × 3 m field plots. The LiDAR point cloud data were converted into a raster format to generate a maximum vegetation height map in 3-m raster cells. The regression relationship between field-based and airborne LiDAR-derived shrub heights was significant ( R 2 =0.77; P value P values