Using gas chromatography to determine winter diets of greater sage-grouse in Utah

Sagebrush (Artemisia spp.) constitutes the majority (>99%) of sage-grouse (Centrocercus spp.) winter diets. Thus, identification and protection of important winter habitats is a conservation priority. However, not all sagebrush may be alike. More information is needed regarding sage-grouse sagebrush winter dietary preferences for application to management. The objective of our research was to determine if chemical analysis of fecal pellets could be used to characterize winter sage-grouse diets as a substitute for more invasive methods. We collected and analyzed fecal pellets and sagebrush samples from 29 different sage-grouse flock locations in northwestern and southcentral Utah. Using gas chromatography, we were able to identify crude terpene profiles that were unique to Wyoming sagebrush (A. tridentata wyomingensis) and black sagebrush (A. nova). We subsequently used the profiles to determine sagebrush composition of sage-grouse fecal pellets, thus reflecting sage-grouse winter diets. This technique provides managers with a tool to determine which species or subspecies of sagebrush may be important in the winter diets of sage-grouse populations. © 2011 The Wildlife Society.     

Sesquiterpene lactones of Artemisia: TLC analysis and taxonomic significance

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

Arbusculin-D from Artemisia arbuscula ssp. Arbuscula

Abstract-Arbusculin-D (I), a new eudesmanolide, has been isolated from Artemisia arbuscula Nutt. ssp. arbuscula and is present also in A. arbuscula Nutt. ssp. thermopola Beetle. It represents a structural variant in the lactone grouping.     

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

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

Grass-Shrub Associations over a Precipitation Gradient and Their Implications for Restoration in the Great Basin,USA

As environmental stress increases positive (facilitative) plant interactions often predominate. Plant-plant associations (or lack thereof) can indicate whether certain plant species favor particular types of microsites (e.g., shrub canopies or plant-free interspaces) and can provide valuable insights into whether “nurse plants” will contribute to seeding or planting success during ecological restoration. It can be difficult, however, to anticipate how relationships between nurse plants and plants used for restoration may change over large-ranging, regional stress gradients. We investigated associations between the shrub, Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis), and three common native grasses (Poa secunda, Elymus elymoides, and Pseudoroegneria spicata), representing short-, medium-, and deep-rooted growth forms, respectively, across an annual rainfall gradient (220–350 mm) in the Great Basin, USA. We hypothesized that positive shrub-grass relationships would become more frequent at lower rainfall levels, as indicated by greater cover of grasses in shrub canopies than vegetation-free interspaces. We sampled aerial cover, density, height, basal width, grazing status, and reproductive status of perennial grasses in canopies and interspaces of 25–33 sagebrush individuals at 32 sites along a rainfall gradient. We found that aerial cover of the shallow rooted grass, P. secunda, was higher in sagebrush canopy than interspace microsites at lower levels of rainfall. Cover and density of the medium-rooted grass, E. elymoides were higher in sagebrush canopies than interspaces at all but the highest rainfall levels. Neither annual rainfall nor sagebrush canopy microsite significantly affected P. spicata cover. E. elymoides and P. spicata plants were taller, narrower, and less likely to be grazed in shrub canopy microsites than interspaces. Our results suggest that exploring sagebrush canopy microsites for restoration of native perennial grasses might improve plant establishment, growth, or survival (or some combination thereof), particularly in drier areas. We suggest that land managers consider the nurse plant approach as a way to increase perennial grass abundance in the Great Basin. Controlled experimentation will provide further insights into the life stage-specific effectiveness and practicality of a nurse plant approach for ecological restoration in this region.     

Sesquiterpene lactones of Artemisia arbuscula and A. tridentata

Chloroform extracts of Artemisia tridentata ssp. vaseyana f. spiciformis (Osterhout) Beetle and Artemisia arbuscula Nutt. ssp. arbuscula gave identical TLC patterns and contained the known germacranolides tatridin-A (I) and tatridin-B (II), and two new germacranolides deacetyllaurenobiolide (III) and spiciformin (IV). The structures of these lactones were shown through spectral studies and chemical transformations. Deacetyllaurenobiolide was converted to the known germacranolide laurenobiolide (IIIb) and spiciformin (IV) was synthesized from deacetyllaurenobiolide along with an isomeric epoxy lactone (V).     

Combined drought and episodic freezing effects on seedlings of low- and high-elevation subspecies of sagebrush (Artemisia tridentata)

Big sagebrush ( Artemisia tridentata ) is a dominant shrub throughout much of the arid western United States. Several recognized subspecies differ in physiology, morphology and in their distribution in relation to soil water availability. While several studies have compared mature individuals of these subspecies, there is little information on seedling physiological tolerance to physical stresses. Understanding seedling physiology is essential for predicting how species may respond to changes in temperature and precipitation regimes. Our objective was to examine the drought and freezing tolerance of seedlings of two A. tridentata subspecies: ssp. tridentata , which is found in low-elevation dry sites, and ssp. vaseyana , found in higher, moister sites. We examined growth, gas exchange and quantum yield of chlorophyll a fluorescence from photosystem II (PSII) for seedlings grown in a greenhouse and exposed to two different levels of moisture availability in combination with a simulated growing season freezing event. We found that ssp. tridentata possessed several drought-tolerant characteristics, such as rapid growth rates, thick leaves and low stomatal conductance. Both subspecies shared similar physiological tolerance to the low-moisture treatment but experienced relatively more stress under the freezing treatment. Subspecies vaseyana was more sensitive to freezing when grown with low soil moisture, resulting in reduced stomatal conductance and PSII quantum yield. In contrast, the low-soil moisture treatment did not increase the susceptibility of ssp. tridentata to freezing. These results demonstrate that drought tolerance may be an important trait for seedlings of A. tridentata , but stress because of freezing damage of seedlings may limit the distribution of the species.     

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

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