Publications

soil aggregate dynamics and plant community response after biosolids application in a semiarid grassland.	biosolids may improve the ecological function of degraded semiarid grasslands, but an understanding of the plant community is essential. an experiment was established in 2001 to determine the effects of a single surface application of biosolids on soil aggregate stability and the composition of the plant community in a semiarid grassland in british columbia, canada. four treatments were evaluated: (i) surface biosolids application at 20 (bio-20) and (ii) 60 mg ha (bio-60), (iii) mineral fertiliz ...	2016	27695737
wildfire, climate, and invasive grass interactions negatively impact an indicator species by reshaping sagebrush ecosystems.	iconic sagebrush ecosystems of the american west are threatened by larger and more frequent wildfires that can kill sagebrush and facilitate invasion by annual grasses, creating a cycle that alters sagebrush ecosystem recovery post disturbance. thwarting this accelerated grass-fire cycle is at the forefront of current national conservation efforts, yet its impacts on wildlife populations inhabiting these ecosystems have not been quantified rigorously. within a bayesian framework, we modeled 30 y ...	2016	27791084
development of single-nucleotide polymorphism markers for bromus tectorum (poaceae) from a partially sequenced transcriptome.	bromus tectorum (poaceae) is an annual grass species that is invasive in many areas of the world but most especially in the u.s. intermountain west. single-nucleotide polymorphism (snp) markers were developed for use in investigating the geospatial and ecological diversity of b. tectorum in the intermountain west to better understand the mechanisms behind its successful invasion.	2016	27843723
biotic resistance and disturbance: rodent consumers regulate post-fire plant invasions and increase plant community diversity.	biotic resistance and disturbance are fundamental processes influencing plant invasion outcomes; however, the role of consumers in regulating the establishment and spread of plant invaders and how disturbance modifies biotic resistance by consumers is unclear. we document that fire in combination with experimental exclusion of rodent consumers shifted a native desert shrubland to a low-diversity, invasive annual grassland dominated by bromus tectorum (cheatgrass). in contrast, burned plots with ...	2016	27859155
phytotoxic activity against bromus tectorum for secondary metabolites of a seed-pathogenic fusarium strain belonging to the f. tricinctum species complex.	the winter annual grass bromus tectorum (cheatgrass) has become highly invasive in semiarid ecosystems of western north america. in these areas, a natural phenomenon, complete cheatgrass stand failure ('die-off'), is apparently caused by a complex interaction among soilborne fungal pathogens. several fusarium strains belonging to the fusarium tricinctum species complex were isolated from these soils and found to be pathogenic on b. tectorum seeds. one of these strains was produced in cheatgrass ...	2017	28278617
ecological genetics of seed germination regulation in bromus tectorum l. : i. phenotypic variance among and within populations.	regulation of seed germination phenology is an important aspect of the life history strategy of invading annual plant species. in the obligately selfing winter annual grass bromus tectorum, seeds are at least conditionally dormant at dispersal in early summer and lose dormancy through dry-afterripening. patterns of germination response at dispersal vary among populations and sometimes across years within populations. to assess the relative contribution of genotype and maturation environment to t ...	1999	28308050
ecological genetics of seed germination regulation in bromus tectorum l. : ii. reaction norms in response to a water stress gradient imposed during seed maturation.	the probability that a seed will germinate depends on factors associated with genotype, maturation environment, post-maturation history, and germination environment. in this study, we examined the interaction among these sets of factors for 18 inbred lines from six populations of bromus tectorum l., a winter annual grass that is an important weed in the semi-arid western united states. seeds of this species are at least conditionally dormant at dispersal and become germinable through dry-afterri ...	1999	28308051
competition between bromus tectorum l. and poa pratensis l.: the role of light.	bromus tectorum l. dominates sites of large-scale disturbance, while poa pratensis l. dominates the sites of small-scale disturbance in the festuca/symphoricarpos habitat type in eastern washington (usa). the role of incident irradiation in influencing these distributions was examined using field and glasshouse experiments. glasshouse grown swards of b. tectorum growing beneath an established canopy of p. pratensis displayed larger biomass and higher survival when exposed to supplemental light v ...	1983	28309370
microsite utilization by bromus tectorum l. and poa pratensis l. in a meadow steppe community.	emergence of bromus tectorum l. and poa pratensis l., two dominant alien grasses in eastern washington, from 24 microsites was monitored in spring and autumn 1979. spring emergence of b. tectorum reached a maximum on north-facing slopes of artificially constructed pocket gopher mounds and burrows while spring emergence of p. pratensis was maximized on both north-and southfacing slopes of mounds. earliest autumn emergence of b. tectorum seedlings was in fissures of 0.5 cm, 1 cm, and 2 cm depth wh ...	1983	28310225
the use of stable carbon isotope analysis in rooting studies.	stable carbon isotope analysis was evaluated as a means of predicting the relative proportions of c3 and c4 root phytomass in species mixtures. the following mixtures of c3 and c4 species were used: 1) big bluestem (andropogon gerardii)/cheatgrass (bromus tectorum), 2) little bluestem (schizachyrium scoparium)/cheatgrass, and 3) sorghum (sorghum bicolor)/sunflower (helianthus annuus). there was a significant correlation (p<0.01) between % c4 phytomass and stable carbon isotope values for each of ...	1985	28311309
native seed preferences of shrub-steppe rodents, birds and ants: the relationships of seed attributes and seed use.	this study established the preferences of shrubsteppe granivores among seeds of 6 common sagebrushsteppe plants and related the preferences observed to physical and nutritional attributes of the seeds. seeds of big sagebrush (artemisia tridentata), cheatgrass (bromus tectorum), indian ricegrass (oryzopsis hymenoides), western wheatgrass (pascopyrum smithii), bitterbrush (purshia tridentata) and green needlegrass (stipa viridula) were placed in groups of petri dishes designed such that seed remov ...	1986	28311774
edaphic limitations to growth and photosynthesis in sierran and great basin vegetation.	soils derived from hydrothermally altered andesite support unique communities of sierran conifers (pinus ponderosa laws. and p. jeffreyi grev. and balf.) amongst sagebrush (artemisia tridentata nutt.) vegetation in the western great basin. plants grown in soil derived from hydrothermally altered bedrock had lower growth rates, total biomass, and net photosynthetic rates than plants grown in soil derived from unaltered andesite of the same formation. total dry mass was 10 to 28% lower for conifer ...	1989	28312357
impact of early root competition on fitness components of four semiarid species.	plant demographic and root exclusion approaches were used to examine the influence of roots of adult artemisia tridentata, agropyron desertorum, and agropyron spicatum individuals on seedling survival of four c3 semiarid species, three perennials, ar. tridentata, ag. desertorum, ag. spicatum, and an annual, bromus tectorum. furthermore, height of ar. tridentata seedlings and seed production of b. tectorum were assessed. the probability of a seedling being alive significantly depended on the seed ...	1990	28312551
comparison of skewness coefficient, coefficient of variation, and gini coefficient as inequality measures within populations.	the moment skewness coefficient, coefficient of variation and gini coefficient are contrasted as statistical measures of inequality among members of plant populations. constructed examples, real data examples, and distributional considerations are used to illustrate pertinent properties of these statistics to assess inequality. all three statistics possess some undesirable properties but these properties are shown to be often unimportant with real data. if the underlying distribution of the vari ...	1989	28312587
ecological genetics of bromus tectorum : i. a hierarchical analysis of phenotypic variation.	an understanding of how genetic differentiation and phenotypic plasticity may interact to promote the spread of an introduced species requires information on the hierarchical distribution of genetic variation within the species in its new range. for example, a lack of genetic variation within marginal populations of an introduced species may slow its rate of spread into new habitats. in a glasshouse study, we examined the phenotypic variation among populations, among families, within families, a ...	1991	28312734
ecological genetics of bromus tectorum : ii. intraspecific variation in phenotypic plasticity.	for bromus tectorum, an alien annual grass now widespread in western north america, we assessed the sensitivity of the phenotypic expression of populational differences in phenology and demography to variation in plant density. plants were grown in an unheated glasshouse from seeds collected from six habitat types located along a moisture-temperature gradient. survival to flowering was high with a mean overall survival of 91%. survival was highest among plants from the coolest, most mesic site. ...	1991	28312735
ecological genetics of bromus tectorum : iii. the demography of reciprocally sown populations.	by incorporating demographic analyses of fitness components (e.g., survival and reproduction) within a reciprocal sowing design, we tested for 3 consecutive years whether local adaptation has occurred in the alien grass bromus tectorum (cheatgrass) within 7 habitats along an environmental gradient from arid steppe to subalpine forest in the intermontain region of western north america. patterns of emergence and survival were strongly influenced by the local environment. in terms of survival, exp ...	1991	28312736
the population biology of bromus tectorum in forests: distinguishing the opportunity for dispersal from environmental restriction.	with increasing elevation and corresponding changes in the macroclimate, forest zones in the intermountain region of western north america are often dominated in turn by pinus ponderosa, pseudotsuga menziesii, abies grandis, an thuja plicata. bromus tectorum (cheatgrass), and introduced annual grass now abundant in the region's steppe, is uncommon in mature stands representative of these forest zones. in order to determine whether b. tectorum is largely excluded from these forests by insufficien ...	1990	28312969
the population biology of bromus tectorum in forests: effect of disturbance, grazing, and litter on seedling establishment and reproduction.	the effect of tree canopy, understory, herbivores, and litter depth on seedling establishment, survival, and reproduction of the alien grass, bromus tectorum (cheatgrass), was examined in a series of experiments in four forest habitat types in western north america. higher recruitment, survival, and reproduction on clearcuts, which would be expected if the overstory alone is limiting the distribution of cheatgrass in forests, were not observed. removing the understory in an otherwise undisturbed ...	1990	28312970
the effect of shading on photosynthesis, growth, and regrowth following defoliation for bromus tectorum.	the effect of full sunlight, 60%, or 90% attenuated light on photosynthetic rate, growth, leaf morphology, dry weight allocation patterns, phenology, and tolerance to clipping was examined in the glasshouse for steppe populations of the introduced grass, bromus tectorum. the net photosynthetic response to light for plants grown in shade was comparable to responses for plants grown in full sunlight. plants grown in full sunlight produced more biomass, tillers and leaves, and allocated a larger pr ...	1990	28312971
soil water exploitation after fire: competition between bromus tectorum (cheatgrass) and two native species.	causes for the widespread abundance of the alien grass bromus tectorum (cheatgrass) after fire in semiarid areas of western north america may include: (1) utilization of resources freed by the removal of fireintolerant plants; and (2) successful competition between b. tectorum and individual plants that survive fire. on a site in northwestern nevada (usa), measurements of soil water content, plant water potential, aboveground biomass production, water use efficiency, and b. tectorum tiller densi ...	1990	28313235
species' traits help predict small mammal responses to habitat homogenization by an invasive grass.	invasive plants can negatively affect native species, however, the strength, direction, and shape of responses may vary depending on the type of habitat alteration and the natural history of native species. to prioritize conservation of vulnerable species, it is therefore critical to effectively predict species' responses to invasive plants, which may be facilitated by a framework based on species' traits. we studied the population and community responses of small mammals and changes in habitat ...	2017	28317278
when perception reflects reality: non-native grass invasion alters small mammal risk landscapes and survival.	modification of habitat structure due to invasive plants can alter the risk landscape for wildlife by, for example, changing the quality or availability of refuge habitat. whether perceived risk corresponds with actual fitness outcomes, however, remains an important open question. we simultaneously measured how habitat changes due to a common invasive grass (cheatgrass, bromus tectorum) affected the perceived risk, habitat selection, and apparent survival of a small mammal, enabling us to assess ...	2017	28331590
effects of carbohydrate and nitrogen supplementation on fermentation of cheatgrass () in a dual-flow continuous culture system.	cheatgrass (cg; ), an introduced winter annual grass, is an aggressive invader of the sagebrush community in the western united states. because of its greater flammability, mature cg constitutes a fire hazard leading to repeated wildfires. one fuel-reduction strategy is livestock grazing. the objective of this study was to evaluate the effects of urea, molasses, or a combination of urea and molasses supplementation of a cg-based diet on digestibility, microbial fermentation, bacterial protein sy ...	2017	28380537