Mule deer foraging preference among five sagebrush ( Artemisia L.) taxa

The hypothesis that sagebrush taxa are equally utilized by mule deer ( Odocoileus hemionus hemionus ) on winter range was tested. Five taxa were studied for 10 years at 2 locations. The taxa were Artemisia tridentata ssp. tridentata (basin big sagebrush), A. t. ssp. wyomingensis (Wyoming big sagebrush), A. t. ssp. vaseyana (mountain big sagebrush), A. tripartita ssp. tripartita (tall threetip sagebrush), and A. arbuscula ssp. arbuscula (low sagebrush). Possible mule deer preferences were determined each year individually for the 2 sites. Utilization was high enough to conclude all taxa are important forage, but not excessive enough to mask preference. Artemisia tridentata ssp. vaseyana (34.4%) and A. arbuscula ssp. arbuscula (35.6%) were preferred over A. t. ssp. wyomingensis (10.9%) and A. t. ssp. tridentata (6.8%) at the Ashbough site. At the Scudder site there were few differences in preference for A. t. ssp. vaseyana (32.1%), A. t. ssp. wyomingensis (28.8%), and A. tripartita ssp. tripartita (32.0%). While ungulates often demonstrate a preference among taxa, all sagebrush taxa are a potentially valuable forage source.     

Ecological classification and monitoring model for the Wyoming big sagebrush shrubsteppe habitat type of northeastern Wyoming

The purposes of this study were to develop a multivariate statistical model related to plant succession, to classify by seral stage, and to monitor succession in Wyoming big sagebrush shrubsteppe habitat ( Artemisia tridentata ssp. wyomingensis / Agropyron smithii–Bouteloua gracilis ) in Thunder Basin National Grassland, Wyoming. This model can be used by range and wildlife managers to evaluate management alternatives by assessing changes in plant species cover and composition within and between seral stages. Four ecological seral stages that represent early to late succession were quantitatively identified with an estimated 92% accuracy. Three key plant species provided the necessary information to define seral stages and monitor trends. Percent canopy cover and percent frequency (used to calculate index values: % canopy cover × % frequency of occurrence) of Wyoming big sagebrush ( Artemisia tridentata ssp. wyomingensis ), western wheatgrass ( Agropyron smithii ), and blue grama ( Bouteloua gracilis ) are the only field measurements required for this model.     

Vegetation response to prescribed fire in Dinosaur National Monument

Much of western North America is dominated by dense, monotypic, late seral stands of big sagebrush ( Artemisia tridentata Nutt.). These stands often have depauperate understories with limited species richness, diversity, and herbaceous cover. The National Park Service at Dinosaur National Monument, Colorado, is using both strategic and natural prescribed fire in Wyoming big sagebrush ( Artemisia tridentata ssp. wyomingensis Beetle and Young) communities to foster intra-community (α -scale) and landscape diversity. This study analyzed an accumulated foliar cover data set between paired burn and control areas on 6 different sites during the last 20 years. Across the monitoring period, mean total vegetation cover of all combined sites was 44% control and 42% burn. Total vegetation cover in burn areas was higher than or equal to paired control areas within 2-3 years post-burn. Shrubs were essentially eliminated in burn areas, but perennial grass cover was 10-35% higher. Mean number of species on all sites and years combined was 17 control and 18 burn. Species richness was different on only 1 site-year, Dry Woman 1995 ( P = 0.001, 15 control, 9 burn). Species similarity by site and between treatments ranged from 44% to 75%. Differences in Shannon-Weiner diversity index values between paired sites occurred in 6 of 20 years ( P < 0.05). Index value differences on these 6 sites were due to a large annual grass component in burn areas. Prescribed burning successfully shifted late successional sagebrushdominated communities to earlier herbaceous-dominated successional stages without lowering total vegetation cover, while maintaining -scale diversity and species richness.     

Development and longevity of ephemeral and perennial leaves on Artemisia tridentata Nutt. ssp. wyomingensis

Big sagebrush ( Artemisia tridentata Nutt.) is one of the most successful plants in the Great Basin based on its abundance and wide distribution. The development of dimorphic leaves may be an important mechanism attributing to its adaptive and competitive abilities. Development, persistence, and proportions of ephemeral and perennial leaves on Wyoming big sagebrush ( Artemisia tridentata Nutt. ssp. wyomingensis ) were studied for two years. The large ephemeral leaves are the first to develop in early spring. As early developing ephemerals mature and stems elongate, new ephemeral and perennial leaves develop in the axes of these large ephemerals. Perennial leaves expanded in the summer of their first growing season, persisting on the shrub until their abscission during summer drought of the second growing season. Plants maintained 33% of their leaf weight through the winters of 1985 and 1986. Active leaf and stem growth occurred at soil water potentials above &ndash;0.2 MPa.     

Correlation of neighborhood relationships, carbon assimilation, and water status of sagebrush seedlings establishing after fire

Interactions of Artemisia tridentata ssp. vaseyana (mountain big sagebrush) and neighboring herbs may affect community development following fire in sagebrush steppe. Dry mass, photosynthesis, and water relations were measured for seedlings of A. tridentata ssp. vaseyana occurring at different distances from neighboring herbs in the initial growing seasons following fire, when herbs dominate plant community cover. Seedling mass significantly increased as distance to neighboring herbs increased, although a low r 2 indicated that mass was also affected by other sources of variation. Carbon assimilation ( A net ) was also greater for A. tridentata ssp. vaseyana seedlings in microsites farther from herbs, except during those sampling dates when A net and water availability were at low levels. Contrary to our expectations, water status of seedlings was not correlated with their distances to neighboring herbs, and supplemental watering did not affect the slope of the relationship between seedling mass and distance to neighboring herbs. These findings suggest that negative relationships between A. tridentata ssp. vaseyana seedlings and herbs establishing after fire are not likely due to competition over water and may instead result from interactions over factors not measured here (e.g., nutrients).     

Nest-site selection by Sage Thrashers in southeastern Idaho

Nest sites selected by Sage Thrashers ( Oreoscoptes montanus ) in southeastern Idaho were characterized and compared with available habitat. Microhabitats within 5 m of nests had taller and more aggregated shrubs and less bare ground than the study area in general. Big sagebrush ( Artemisia tridentata wyomingensis ) plants used for nesting were taller than average ,available shrubs, had greater foliage density, were more often living, and more frequently had branches and foliage within 30 cm of the ground. Nest placement was specific with respect to relative nest height and distance from the top and perimeter of the support shrub. Sage Thrashers disproportionately used easterly exposures and underused westerly exposures for their nests.     

Invasion of big sagebrush ( Artemisia tridentata ) by white fir ( Abies concolor ) on the southeastern slopes of the Warner Mountains, California

White fir ( Abies concolor ) appears to be invading vegetation dominated by big sagebrush ( Artemisia tridentata ) on the southeastern slopes of the Warner Mountains of extreme northeastern California. The time of initial tree establishment within the shrubs was determined by increment borings. Possible causes of the invasion involving specific climatic conditions, fire history, and grazing use of the area during years of the establishment were explored. Heavy grazing by domestic livestock, particularly sheep, appears responsible for altering the sagebrush - grass vegetation and allowing tree invasion.     

Recovery and germinability of native seed fed to cattle

Using livestock as seed dispersal agents may be an effective method for increasing species diversity on degraded and previously seeded rangelands. We quantified seed passage and recovery rates, and post-passage germinability of Wyoming big sagebrush ( Artemisia tridentata Nutt. ssp. wyomingensis Beetle & Young), bottlebrush squirreltail ( Elymus elymoides [Raf.] Swezey), and gooseberry globemallow ( Sphaeralcea grossulariaefolia [H. & A.] Rydb.) by feeding Holstein heifers seeds of each species at 3 levels (15,000; 30,000; and 60,000 seeds) over a period of 3 weeks. One-kg fecal samples were collected 1, 2, 3, and 4 days after seed ingestion. Undamaged seeds were extracted from the samples and tested for germinability. Globemallow had the highest percentage of recovered, undamaged seed, followed by squirreltail and sagebrush. Globemallow and sagebrush seed passage was highest on Day 1, after which seed numbers dropped sharply. Squirreltail passage and recovery were more consistent through time, with higher seed recovery at lower seed feeding levels. Post-passage germinability was highest for squirreltail and globemallow on Day 1. Sagebrush germination was negligible. Differences in physical seed properties (size, shape, and seed coat) likely influenced interspecies variation in passage, recovery, and germinability. Globemallow and squirreltail seeds may be suited for livestock dispersal, but sagebrush seeds are not.     

Juniperus occidentalis (western juniper) establishment history on two minimally disturbed research natural areas in central Oregon

While a trend toward western juniper ( Juniperus occidentalis spp. occidentalis ) super-dominance in big sagebrush ( Artemisia tridentata ) communities of the Pacific Northwest since the late 1800s has been well documented, establishment dates of western juniper in less disturbed environments have not. In this paper we document the establishment history of western juniper on 2 minimally disturbed research natural areas that have substantial differences in their physical characteristics. On each site we randomly established twenty 0.05-ha plots to obtain per hectare counts of mature and juvenile western juniper and to obtain a sample of 100 trees closest to the plot center. These trees were then dated using standard dendrochronological techniques. The lower-elevation, more xeric site has an establishment history that suggests it is an emerging western juniper woodland, with the majority of trees sampled establishing since 1978. The higher-elevation site is an older, well-established woodland with a more even temporal distribution of trees. These results suggest that suitable establishment sites may switch from canopy dependence in emerging woodlands to open sites in mature woodlands and that neither domestic livestock grazing nor active fire suppression is a required mechanism for establishment.     

Wintering mule deer preference for 21 accessions of big sagebrush

Wintering mule deer showed differential browsing preference among 21 accessions of big sagebrush ( Artemisia tridentata ) grown on gardens on three different mule deer herd ranges. The Hobble Creek accession of big sagebrush was significantly preferred over the other 20 accessions across all three sites and for all three years. Accessional preference means for the study period for all sites combined ranged from 28.3 to 57.5%. The data collected support the planned release of the Hobble Creek accession as a superior cultivar of big sagebrush for use on mule deer winter ranges. Plant coumarin content was primarily under genetic control, but site factors also had an effect. Assay for coumarin compounds is useful in determining subspecies of A. tridentata but not for precise prediction of mule deer browsing preference.     

Response of sagebrush steppe species to elevated CO 2 and soil temperature

Elevated atmospheric CO 2 may cause long-term changes in the productivity and species composition of the sagebrush steppe. Few studies, however, have evaluated the effects of increased CO 2 on growth and physiology of species important to this ecosystem. Since the response of plants to elevated CO 2 may be limited by environmental factors, soil temperature was also examined to determine if low soil temperatures limit CO 2 response. To determine how CO 2 and soil temperature affect the growth of species native to the sagebrush steppe, bottlebrush squirreltail [ Elymus elymoides (Raf.) Swezey], Thurber needlegrass ( Stipa thurberiana Piper), and Wyoming big sagebrush ( Artemisia tridentata ssp. wyomingensis Beetle) were grown in ambient (374 mL L -1 ) or high (567 mL L -1 ) CO 2 and low (13° C) or high (18° C) soil temperature for approximately 4 months. Although soil temperature affected the growth of squirreltail and needlegrass, temperature did not modify their response to elevated CO 2 . Total biomass of sagebrush was consistent across soil temperature and CO 2 treatments, reflecting its slow-growing strategy. All 3 species had higher leaf water-use efficiency at elevated CO 2 due to higher net photosynthesis and lower transpiration rates. We conclude that elevated CO 2 and soil warming may increase the growth of grasses more than shrubs. Field studies in the sagebrush steppe are necessary to determine if differences in biomass, resulting from changes in CO 2 and soil temperature, are exhibited in the field.     

Plant age/size distributions in black sagebrush ( Artemisia nova ): effects on community structure

The demography of black sagebrush ( Artemisia nova Nelson) was investigated in the Buckskin Mountains of western Nevada to determine patterns of stand renewal in sagebrush communities currently free from wildfires. Biomass sampling was conducted to develop growth classes that reflected apparent age of the shrubs. The density of black sagebrush plants was twice that of basin big sagebrush ( A. tridentata ssp. tridentata Nutt.) in adjacent communities on contrasting soils (2.2 versus 1.1 plants per m 2 ). Black sagebrush accumulated only 75% as much woody biomass as big sagebrush. Regression equations were developed and tested for predicting total woody biomass, current annual growth (CAG), and leaf weight of black sagebrush plants. Apparent age classes were developed both for the black sagebrush plants and the sub-canopy mounds on which they grew. Discriminant analysis was used to test this classification system. Plant succession, apparently controlled by nitrate content of the surface soil, appeared to eliminate the successful establishment of black sagebrush seedlings on the mounds. After the shrubs die, the mounds eventually deflate. We propose that mounds reform around shrub seedlings, but because seedling establishment is so rare in these communities, this could not be verified.     

Effects of browsing by native ungulates on the shrubs in big sagebrush communities in Yellowstone National Park

The effects of elk ( Cervus elaphus ), pronghorn ( Antilocapra americana ), and mule deer ( Odocoileus hemionus ) browsing on shrubs in big sagebrush ( Artemisia tridentata ) communities were monitored over a 31-year period in Yellowstone National Park. Ungulates were restricting Wyoming big sagebrush (spp. wyomingensis ) heights, size, and recruitment on the lower-elevation stratum only, while no such suppression was observed on the high-elevation stratum. Parallel increases in mountain big sagebrush (spp. vaseyana ) densities and cover occurred over the study period on both browsed and unbrowsed sites at the higher-elevation stratum, although big sagebrush, green rabbitbrush ( Chrysothamnus viscidiflorus ), and horsebrush ( Tetradymia canescens ) were slightly taller and crown sizes were slightly larger on unbrowsed than browsed sites. Wyoming big sagebrush utilization (percent leader use) was eight times higher (￣ x = 87 ± 7.2% by pronghorns, mule deer, and elk) on the low-elevation winter ranges stratum (the Boundary Line Area [BLA] portion of the winter range), while mostly mountain big sagebrush with leader use averaged only 11 ± 4.1% (nearly all by elk) on the high-elevation range stratum. In addition, annual aboveground biomass production of big sagebrush did not differ between browsed and unbrowsed study sites on the high-elevation stratum of the winter range. Population turnover was higher on browsed plots versus unbrowsed plots. No difference was observed in percent dieback of big sagebrush adult plants between browsed and unbrowsed plots at the higher stratum. Browsing did not influence the number of leaves or seedstalks per plant ( P > .05), but leaves averaged 45% longer and seedstalks 42% longer on browsed big sagebrush. Ungulate browsing, however, apparently suppressed production, germination, and survival of Wyoming big sagebrush on the low-elevation stratum. Numbers of Wyoming big sagebrush declined 43% and cover declined 29%, 1957-1990, on browsed sites on the BLA. Annual biomass production on browsed sites at the low-elevation stratum was only 6-35% that of unbrowsed sites, and big sagebrush recruitment was less on browsed sites. Percent leader use of big sagebrush did not differ between the period of ungulate reductions, 1962-1969, and the 1980s on the lower stratum (￣ x = 87% leader use), but utilization was less on higher portions of the winter range during the period of elk reductions (￣ x = 2%) than during the 1980s following cessation of elk controls (￣ x = 11%).     

Randomly amplified polymorphic DNA analysis (RAPD) of Artemisia subgenus Tridentatae species and hybrids

Species of Artemisia (subgenus Tridentatae ) dominate much of western North America. The genetic variation that allows this broad ecological adaptation is facilitated by hybridization and polyploidization. Three separate studies were performed in this group using randomly amplified polymorphic DNA (RAPD). Fifty-seven 10-mer primers generated nearly 400 markers from genomic DNA obtained from leaf tissue. These studies were (1) a measure of the variability of plants within and between populations and between subspecies using 5 A. tridentata ssp. wyomingensis populations, 2 A. cana ssp. cana populations, and 1 A. cana ssp. viscidula population; (2) an examination of the hypothesis that tetraploid (4 x ) Artemisia tridentata spp. vaseyana derives de novo from diploid (2 x ) populations via antopolyploidy; and (3) an examination of the validity of the status of putative hybrids that have been produced by controlled pollination. These later hybrid combinations- A. tridentata ssp. tridentata × A. t. ssp. vaseyana , A. t. ssp. wyomingensis × A. tripartita , and A. cana ssp. cana A. tridentata ssp. wyomingensis - were made to combine traits of parental taxa in unique combinations with possible management application. RAPD marker data were subjected to similarity and UPGMA clustering analyses. RAPD markers were effective in measuring genetic diversity at different systematic levels. Individual plants within a population were approximately 55% to > 80% similar to one another; populations within subspecies gave corresponding values of similarity, probably a result of the combined effects of large population sizes and wind pollination. The 2 subspecies of A. cana were approximately 45% similar. At least some 4 x populations of A. tridentata ssp. vaseyana apparently derive de novo from 2 x plants based on their being embedded in 2 x phenogram groups, thus reinforcing evidence that autopolyploidy plays an important role in Tridentatae population biology. Two ( A. tridentata ssp. tridentata × A. t. ssp. vaseyana and A. cana ssp. cana × A. tridentata ssp. wyomingensis ) of the 3 putative hybrid combinations were confirmed to include hybrids. These hybrids may have potential in management applications. Additional use of RAPD technology combined with other techniques may be useful in delimiting genetic characteristics and in guiding artificial selection in Tridentatae .     

Planting depth of 'Hobble Creek' mountain big sagebrush seed

We conducted a greenhouse study in which 'Hobble Creek' mountain big sagebrush ( Artemisia tridentata ssp. vaseyana ) seeds were planted at various depths in soil to determine the optimal planting depth. Results showed that the optimal planting depth is 5 mm or less.     

Seasonal patterns of arthropod diversity and abundance on big sagebrush, Artemisia tridentata

The sagebrush biotype is the largest in the western United States. This vast sagebrush community is thought to harbor equally vast and diverse arthropod communities, but these remain little explored. Our objective was to examine the diversity, abundance, and seasonal phenology of arthropod taxa found on the dominant shrub of the sagebrush ecosystem, big sagebrush ( Artemisia tridentata ). We wanted to improve understanding of this little-studied arthropod assemblage that may play significant roles in the dynamics of sagebrush populations and the sagebrush ecosystem. We sampled free-living and gall-forming arthropods from a stratified random sample of sagebrush plants at the Barton Road Ecological Research Area, Idaho, resulting in a sample of over 8000 individuals and 232 morphospecies. Species richness and abundance declined from May to August, and abundance of most taxa similarly declined over the summer. A few taxa, including Acari (mites), were notably more abundant in August. Fluid feeders were the most diverse and abundant free-living feeding guild during all months and comprised up to 79% of morphospecies. The gall formers included 4713 individuals of 12 species of gall flies ( Rhopalomyia spp.), primarily (97%) R. ampullaria. Abundance of galls increased from small to large (presumably young to old) plants. Overall, A. tridentata was host to a high diversity of arthropods, some of which have potential to cause or mitigate significant damage to their host plant. Arthropods seem likely to have the greatest impact on sagebrush early in the growing season, when they are most diverse and abundant. Documentation of the full diversity of arthropods associated with sagebrush required samples taken throughout the growing season, but a single sample early in the growing season captured a high proportion of taxa.     

Fishtail Mesa: a vegetation resurvey of relict area in Grand Canyon National Park, Arizona

Relict sites are geographically isolated areas that are undisturbed by direct and indirect human influences. These sites facilitate long-term ecological monitoring by providing a reference for gauging impacts occurring elsewhere. Knowledge gained through comparing vegetation change on matched relict and proximal disturbed areas can help partition the causes of change into natural and human-produced components. Fishtail Mesa in Grand Canyon National Park is a 439-ha relict site that is inaccessible to domestic livestock. Human visitation is infrequent and irregular, and fires have never been suppressed or managed. In 1958, U.S. Forest Service range scientists conducted a survey of Fishtail Mesa to gather reference data on vegetation, wildlife, and soils. Vegetation sampling was conducted using a method called the ";";elb.";"; We returned to Fishtail Mesa in May 1996 to perform a general vegetation and floristic survey, assess the extent of vegetation change after 38 years, and evaluate the suitability of the site as a location for long-term surveillance of ecological change. Fishtail Mesas vegetation consists primarily of a Pinus edulis (pinyon) and Juniperus osteosperma (Utah juniper) woodland with an Artemisia tridentata (sagebrush) understory, or tree-type (310.9 ha), and an Artemisia and Poa fendleriana (mutton grass) steppe, or shrub-type (127.5 ha). Since 1958 vegetation changes in both shrub- and tree-types have been limited to only a few species. In the shrub-type we detected slight increases from 1958 to 1996 in both Pinus and Juniperus , and reexamination of 1958 photo sites confirmed that Pinus and Juniperus are reoccupying the shrub-type. Artemisia cover declined from 1958 to 1996, whereas Poa increased from near trace amounts in 1958 to moderate cover in 1996. In the tree-type, Poa has increased from 1958 to 1996, while Artemisia , Juniperus , and Pinus showed no apparent change. Other species such as Ephedra torreyana (Torrey joint-fir), Opuntia polyacantha (prickly pear), and Gutierrezia sarothrae (snakeweed) have decreased. Vegetation analysis aided by TWINSPAN revealed that the shrub-type is defined more on the basis of absence of Pinus and Juniperus rather than any special association of differential species with a high preference for this type. We interpret the ";";invasion";"; of the shrub-type by Pinus and Juniperus as a ";";reoccupation.";"; Indirect ordination using DECORANA inferred 2 environmental gradients, a moisture gradient and perhaps a substrate texture gradient, that appeared to influence vegetation distribution on Fishtail Mesa. Fishtail Mesa is a valuable relict area for studying the effects of livestock grazing and prescribed fire. It should be designated a Federal Research Natural Area based on its vegetation communities, size, and protection afforded by its location in Grand Canyon National Park.     

Lahontan sagebrush ( Artemisia arbuscula ssp. longicaulis ): a new taxon

A new subspecies of Artemisia arbuscula is described, A. arbuscula ssp. longicaulis Winward & McArthur, ssp. Nov. This taxon is a landscape dominant in portions of northwestern Nevada and adjacent California and Oregon at elevations from 1050 to 2000 m on shallow or argillic (clayey) soils. It differs from A. arbuscula ssp. arbuscula in its long floral stalks and large leaves. Morphological, chemical, ecological, and cytological data suggest that it is of hybrid origin. It is hexaploid (6x). We hypothesize that 2x A. arbusucla ssp. arbusucla and 4x A. tridentata ssp. wyomingensis are its parents.     

Spatial relationships among young Cercogarpus ledifolius (curlleaf mountain mahogany)

This study analyzed spatial location patterns Cercocarpus ledifolius Nutt. (cutleaf mountain mahogany) plants, classified as current-year seedling, established seedling, juvenile, and immature individuals, at a central Nevada study site. Most current-year seedlings were located in mahogany stands in which large, mature individuals had the greatest abundance. These stands had greater litter cover and a thicker layer of litter than areas with few current-year seedlings. Most established young Cercocarpus were located in adjacent Artemisia tridentata spp. vaseyana (mountain big sagebrush) communities, or in frequent canopy gaps between relatively few large, mature Cercocarpus . We discuss potential roles of plant litter, root growth characteristics, nurse plants, and herbivory in the establishment and renewal of Cercocarpus communities.