Publications

post-fire seeding on wyoming big sagebrush ecological sites: regression analyses of seeded nonnative and native species densities.	since the mid-1980s, sagebrush rangelands in the great basin of the united states have experienced more frequent and larger wildfires. these fires affect livestock forage, the sagebrush/grasses/forbs mosaic that is important for many wildlife species (e.g., the greater sage grouse (centrocercus urophasianus)), post-fire flammability and fire frequency. when a sagebrush, especially a wyoming big sagebrush (artemisia tridentata ssp. wyomingensis (beetle & a. young)), dominated area largely devoid ...	2009	18790557
the adaptive value of remnant native plants in invaded communities: an example from the great basin.	changes in the species composition of biotic communities may alter patterns of natural selection occurring within them. native perennial grass species in the intermountain west are experiencing a shift in the composition of interspecific competitors from primarily perennial species to an exotic, annual grass. thus traits that confer an advantage to perennial grasses in the presence of novel annual competitors may evolve in invaded communities. here i show that such traits are apparent in populat ...	2008	18686583
genomic organization of ribosomal rna genes in bromus (poaceae).	restriction site maps of the rdna genes of nine bromus species are described. the rdna repeat units ranged from 8.2 to 11.1 kbp in length. intraspecific length variation was observed in the bamhi digestions in three of the nine species. restriction site variation was observed mainly in the intergenic spacer (igs) but was also detected in the coding region. a unique kpni site was present in the igs of bromus tectorum and bromus sericeus (subgenus stenobromus); in addition, b. sericeus contained a ...	1996	18469887
prevalence of pollen sensitization in younger children who have asthma.	it is commonly believed that young children are incapable of pollen sensitization; therefore, skin testing usually is not performed to these allergens. the purpose of this study was to identify the frequency of positive skin tests to outdoor allergens among younger children who have asthma. patients who have asthma, aged 6 months to 10 years, were evaluated for pollen sensitization over a 10-year period. skin-prick testing was performed to relevant individual aeroallergens including trees, grass ...	2007	18201429
a race for survival: can bromus tectorum seeds escape pyrenophora semeniperda-caused mortality by germinating quickly?	pathogen-seed interactions may involve a race for seed resources, so that seeds that germinate more quickly, mobilizing reserves, will be more likely to escape seed death than slow-germinating seeds. this race-for-survival hypothesis was tested for the north american seed pathogen pyrenophora semeniperda on seeds of the annual grass bromus tectorum, an invasive plant in north america. in this species, the seed germination rate varies as a function of dormancy status; dormant seeds germinate slow ...	2007	17353206
impact of grazing intensity during drought in an arizona grassland.	the ecological benefits of changing cattle grazing practices in the western united states remain controversial, due in part to a lack of experimentation. in 1997 we initiated an experimental study of two rangeland alternatives, cattle removal and high-impact grazing, and compared grassland community responses with those with more conventional, moderate grazing practices. the study was conducted in a high-elevation, semiarid grassland near flagstaff, arizona (u.s.a.). we conducted annual plant su ...	2007	17298514
characterizing the landscape dynamics of an invasive plant and risk of invasion using remote sensing.	improved understanding of the spatial dynamics of invasive plant species may lead to more effective land management and reduced future invasion. here, we identified the spatial extents of nonnative cheatgrass (bromus tectorum) in the north central great basin using remotely sensed data from landsat mss, tm, and etm+. we compared cheatgrass extents in 1973 and 2001 to six spatially explicit landscape variables: elevation, aspect, hydrographic channels, cultivation, roads, and power lines. in 2001 ...	2006	16827008
bromus tectorum invasion alters nitrogen dynamics in an undisturbed arid grassland ecosystem.	the nonnative annual grass bromus tectorum has successfully replaced native vegetation in many arid and semiarid ecosystems. initial introductions accompanied grazing and agriculture, making it difficult to separate the effects of invasion from physical disturbance. this study examined n dynamics in two recently invaded, undisturbed vegetation associations (c3 and c4). the response of these communities was compared to an invaded/ disturbed grassland. the invaded/disturbed communities had higher ...	2006	16602290
net carbon exchange and evapotranspiration in postfire and intact sagebrush communities in the great basin.	invasion of non-native annuals across the intermountain west is causing a widespread transition from perennial sagebrush communities to fire-prone annual herbaceous communities and grasslands. to determine how this invasion affects ecosystem function, carbon and water fluxes were quantified in three, paired sagebrush and adjacent postfire communities in the northern great basin using a 1-m3 gas exchange chamber. most of the plant cover in the postfire communities was invasive species including b ...	2006	16151860
microbial dynamics and carbon and nitrogen cycling following re-wetting of soils beneath two semi-arid plant species.	sporadic summer rainfall in semi-arid ecosystems can provide enough soil moisture to drastically increase co(2) efflux and rates of soil n cycling. the magnitudes of c and n pulses are highly variable, however, and the factors regulating these pulses are poorly understood. we examined changes in soil respiration, bacterial, fungal and microfaunal populations, and gross rates of n mineralization, nitrification, and nh(4) (+) and no(3) (-) immobilization during the 10 days following wetting of dry ...	2005	15490245
ecological genetics of vernalization response in bromus tectorum l. (poaceae).	bromus tectorum (cheatgrass or downy brome) is an exotic annual grass that is dominant over large areas of former shrubland in western north america. to flower in time for seed production in early summer, b. tectorum plants generally require vernalization at winter temperatures, either as imbibed seeds or as established seedlings.	2004	15087300
comparison of soil bacterial communities in rhizospheres of three plant species and the interspaces in an arid grassland.	soil bacteria are important contributors to primary productivity and nutrient cycling in arid land ecosystems, and their populations may be greatly affected by changes in environmental conditions. in parallel studies, the composition of the total bacterial community and of members of the acidobacterium division were assessed in arid grassland soils using terminal restriction fragment length polymorphism (trf, also known as t-rflp) analysis of 16s rrna genes amplified from soil dna. bacterial com ...	2002	11916705
a computerized micro-elisa assay for allergen-specific ige antibodies.	a computer-normalized micro-elisa assay employing horseradish peroxidase and polystyrene microtiter plates (ip assay) for allergen-specific ige antibodies is described. the specificity of the assay was confirmed by heat inactivation and multiple absorption experiments. individual allergen blanks were used to account for the variability in the nonspecific binding among various allergens. the results obtained in milliunits of absorbance were normalized by a computer protocol using four reference s ...	1984	6372431
effect of sagebrush distillate on the germination of cheatgrass seed. bnwl-714.		1968	5306302
effects of moisture and temperature on the physiology of cheatgrass. bnwl-480.		1966	5301018
effect of forage species and season on nutrient digestion and supply in grazing cattle.	1. a total of twenty friesian steers were grazed on pure swards of either perennial ryegrass (lolium perenne cv. melle) or white clover (trifolium repens cv. blanca) from may to late august to examine the effect of forage species and season on nutrient digestion and supply. within each forage species, two daily allowances of forage (i.e. 30 and 60 g dry matter (dm)/kg live weight) were given, and nutrient flow into the small intestine was measured on thirteen separate occasions (viz. seven grass ...	1986	3676197
cross-reactive and unique grass group i antigenic determinants defined by monoclonal antibodies.	as part of a study to probe the immunochemical basis for allergenic cross-reactivity among grass pollens, a series of useful reagents has been prepared. the major grass-pollen allergen, designated group i (gpi), was isolated from five grass pollens (meadow fescue, june grass, sweet vernal grass, redtop grass, and perennial ryegrass). the purified gpi antigens were used to immunize individual groups of balb/c mice. a total of 123 hybridoma-derived anti-gpi monoclonal antibodies (mabs) was produce ...	1987	2434551
allergenicity and cross-reactivity of rye grass pollen extracts revealed by monoclonal antibodies.	using monoclonal antibodies the immunogenic and allergenic characteristics of rye group i were redefined by sds-page analysis and immunoblotting. the purified rye group i from nih possesses a major component of approximately 34000 da against which most of the sera from grass-sensitive patients and none from non-atopic volunteers contain specific ige antibodies. monoclonal antibodies to rye group i were raised and used to purify the antigen and to verify the cross-reactivity between grass extract ...	1986	2422284
diagnostic performance characteristics of the standard phadebas rast, modified rast, and pharmacia cap system versus skin testing.	results from three in vitro assays for allergen-specific ige, the standard phadebas radioallergosorbent test (phrast), modified rast (mrast), and the new pharmacia cap system (cap) were compared with skin prick testing (spt) results in 104 patients with allergic rhinitis and/or asthma and 24 nonatopic controls. five allergens were evaluated: cat, dermatophagoides pteronyssinus, alternaria, june grass, and short ragweed. using spt results as the reference standard, the phrast had the lowest sensi ...	1991	1958005
the cross-reactivity of ige antibodies with pollen allergens. i. analyses of various species of grass pollens.	atopic patients with histories of grass pollen allergy often are sensitive to a variety of species of grasses. using a serum pool from patients sensitive to june grass, we analyzed the reactivity of ige antibodies to seven grasses by the radioallergosorbent test. extracts were analyzed for their inhibitory activities with solid-phase allergens prepared from all of the grass pollen. also samples of serum were exhaustively absorved with solid-phase allergens and the supernatants tested to determin ...	1976	956553
analysis of the potency of extracts of june grass pollen by their inhibitory capacities in the radioallergosorbent test.	the potencies of 11 commercial extracts of june grass pollen were analyzed by skin test end point titrations and compared to potencies as determined in vitro (1) by the radioallergosorbent test (rast), (2) by group i antigen content, and (3) by protein nitrogen units (pnu). rast potencies were determined by the capacity of the extract to inhibit the binding of ige antibody to solid-phase allergen, and they were expressed as the quantity of extract required for 50% inhibition of binding. potencie ...	1976	947976
induction of anti-timothy pollen reaginic antibodies and their cross-reactivity in the rat.	anti-timothy pollen reaginic antibody produced in rats cross-reacted with a large number of grass pollen antigens (orchard, june grass, perennial rye grass, velvet, meadow fescue, red top and broncho grass), but did not react with bermuda, brome and johnson grass.	1977	911069
accumulation of 99tc by tumbleweed and cheatgrass grown on arid soils.		1978	730520
the effect of soil affixants on germination, emergence, and growth of cheatgrass and russian thistle.		1978	701042