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Sample records for cheatgrass bromus tectorum

  1. Multitemporal spectral analysis for cheatgrass (Bromus tectorum) classification.

    SciTech Connect

    Singh, Nagendra; Glenn, Nancy F

    2009-07-01

    Operational satellite remote sensing data can provide the temporal repeatability necessary to capture phenological differences among species. This study develops a multitemporal stacking method coupled with spectral analysis for extracting information from Landsat imagery to provide species-level information. Temporal stacking can, in an approximate mathematical sense, effectively increase the 'spectral' resolution of the system by adding spectral bands of several multitemporal images. As a demonstration, multitemporal linear spectral unmixing is used to successfully delineate cheatgrass (Bromus tectorum) from soil and surrounding vegetation (77% overall accuracy). This invasive plant is an ideal target for exploring multitemporal methods because of its phenological differences with other vegetation in early spring and, to a lesser degree, in late summer. The techniques developed in this work are directly applicable for other targets with temporally unique spectral differences.

  2. Genetic variation and local adaptation at a cheatgrass (Bromus tectorum) invasion edge in western Nevada.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cheatgrass (Bromus tectorum) is an invasive weed in western North America primarily found growing at elevations less than 2200 m. We asked whether cheatgrass is capable of becoming adapted to high elevations at a population near a high elevation invasion edge, using a combination of methods, includi...

  3. Fire effects on the mobilization and uptake of nitrogen by cheatgrass (Bromus tectorum L.)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cheatgrass (Bromus tectorum L.), an invasive annual grass, is displacing native species and causing increased fire frequency in the Great Basin of the southwestern United States. Growth and nitrogen uptake patterns by cheatgrass were examined in a greenhouse study using soils from sites with the sa...

  4. Evidence that invasion by cheatgrass (Bromus tectorum L.) increases soil nitrogen availability

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Certain exotic plant species are known to engineer soil processes and thereby facilitate their competitive stature and invasiveness. In a well-characterized winterfat (Krascheninnikovia lanata) community in the Honey Lake Valley of northeastern CA, we tested if cheatgrass invasion (Bromus tectorum L...

  5. The Effect of Herbaceous Species Removal, Fire, and Cheatgrass (Bromus tectorum) on Soil Water Availability in Sagebrush Steppe.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Over the past several decades, cheatgrass (Bromus tectorum) has been continually expanding in the sagebrush steppe ecosystem. There has been very little research that examines why cheatgrass is able to invade these communities. To determine the effects of herbaceous vegetation removal and fire on av...

  6. Bromus Tectorum (Cheatgrass): Monitoring An Invasion For 10 Years

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In a Krascheninnikovia lanata (winterfat) community in the Honey Lake Valley of northeastern, CA we have monitored the effect of B. tectorum (a Eurasian exotic annual grass) invasion on surface soil properties. In 1990 a transect of 13 plots, 50 m apart was established, at which time only plots 1-5 ...

  7. Native Perennial Grasses Show Evolutionary Response to Bromus tectorum (Cheatgrass) Invasion

    PubMed Central

    Goergen, Erin M.; Leger, Elizabeth A.; Espeland, Erin K.

    2011-01-01

    Invasive species can change selective pressures on native plants by altering biotic and abiotic conditions in invaded habitats. Although invasions can lead to native species extirpation, they may also induce rapid evolutionary changes in remnant native plants. We investigated whether adult plants of five native perennial grasses exhibited trait shifts consistent with evolution in response to invasion by the introduced annual grass Bromus tectorum L. (cheatgrass), and asked how much variation there was among species and populations in the ability to grow successfully with the invader. Three hundred and twenty adult plants were collected from invaded and uninvaded communities from four locations near Reno, Nevada, USA. Each plant was divided in two and transplanted into the greenhouse. One clone was grown with B. tectorum while the other was grown alone, and we measured tolerance (ability to maintain size) and the ability to reduce size of B. tectorum for each plant. Plants from invaded populations consistently had earlier phenology than those from uninvaded populations, and in two out of four sites, invaded populations were more tolerant of B. tectorum competition than uninvaded populations. Poa secunda and one population of E. multisetus had the strongest suppressive effect on B. tectorum, and these two species were the only ones that flowered in competition with B. tectorum. Our study indicates that response to B. tectorum is a function of both location and species identity, with some, but not all, populations of native grasses showing trait shifts consistent with evolution in response to B. tectorum invasion within the Great Basin. PMID:21479185

  8. Establishment of cheatgrass (Bromus tectorum L. ) on spent oil shale from the Paraho process

    SciTech Connect

    George, M.R.; McKell, C.M.; Richardson, S.G.

    1981-04-01

    Experiments were conducted in a greenhouse with the following obtectives: (i) to study the emergence and seedling growth of cheatgrass (Bromus tectorum L.) in soil and in Paraho spent oil shale that was either leached, treated with sulfuric acid, covered with soil, or mixed with soil, and (ii) to study emergence and seedling growth of cheatgrass on spent shale that was fertilized with ammonium nitrate and triple superphosphate. The Ec/sub e/ of the spent shale was 14 mmhos/cm, the pH was 9 and the shale was low in plant available N and P. The soil from Federal oil shale lease tract U-a near Bonanza, Utah was a coarse textured alluvium with low moisture retention. Cheatgrass planted on soil alone and shale covered with soil had the highest emergence rates (75 to 86%) and produced the greatest total biomass (8.55 to 13.4 g). Seedling emergence rates on leached and unleached spent shale were 44% and 36%, respectively, and total biomass was < 1 g on either treatment. Seedlings failed to emerge on sulfuric acid-treated spent shale. The addition of sulfuric acid to spent shale increased the EC/sub e/ of the shale to over 21 mmhos/cm. Leached and unleached spent shale was fertilized with N at rates of 0, 28, and 56 kg/ha and P at rates of 0, 24.4, and 48.8 kg/ha. The total biomass for any fertilizer treatment was < 1 g. We conclude that covering shale disposal piles with topsoil may improve the site for successful invasion by a colonizing species such as cheatgrass.

  9. Relative Abundance of and Composition within Fungal Orders Differ between Cheatgrass (Bromus tectorum) and Sagebrush (Artemisia tridentata)-Associated Soils

    PubMed Central

    Weber, Carolyn F.; King, Gary M.; Aho, Ken

    2015-01-01

    Nonnative Bromus tectorum (cheatgrass) is decimating sagebrush steppe, one of the largest ecosystems in the Western United States, and is causing regional-scale shifts in the predominant plant-fungal interactions. Sagebrush, a native perennial, hosts arbuscular mycorrhizal fungi (AMF), whereas cheatgrass, a winter annual, is a relatively poor host of AMF. This shift is likely intertwined with decreased carbon (C)-sequestration in cheatgrass-invaded soils and alterations in overall soil fungal community composition and structure, but the latter remain unresolved. We examined soil fungal communities using high throughput amplicon sequencing (ribosomal large subunit gene) in the 0–4 cm and 4–8 cm depth intervals of six cores from cheatgrass- and six cores from sagebrush-dominated soils. Sagebrush core surfaces (0–4 cm) contained higher nitrogen and total C than cheatgrass core surfaces; these differences mirrored the presence of glomalin related soil proteins (GRSP), which has been associated with AMF activity and increased C-sequestration. Fungal richness was not significantly affected by vegetation type, depth or an interaction of the two factors. However, the relative abundance of seven taxonomic orders was significantly affected by vegetation type or the interaction between vegetation type and depth. Teloschistales, Spizellomycetales, Pezizales and Cantharellales were more abundant in sagebrush libraries and contain mycorrhizal, lichenized and basal lineages of fungi. Only two orders (Coniochaetales and Sordariales), which contain numerous economically important pathogens and opportunistic saprotrophs, were more abundant in cheatgrass libraries. Pleosporales, Agaricales, Helotiales and Hypocreales were most abundant across all libraries, but the number of genera detected within these orders was as much as 29 times lower in cheatgrass relative to sagebrush libraries. These compositional differences between fungal communities associated with cheatgrass- and

  10. Relative abundance of and composition within fungal orders differ between cheatgrass (Bromus tectorum) and sagebrush (Artemisia tridentate)-associated soils.

    PubMed

    Weber, Carolyn F; King, Gary M; Aho, Ken

    2015-01-01

    Nonnative Bromus tectorum (cheatgrass) is decimating sagebrush steppe, one of the largest ecosystems in the Western United States, and is causing regional-scale shifts in the predominant plant-fungal interactions. Sagebrush, a native perennial, hosts arbuscular mycorrhizal fungi (AMF), whereas cheatgrass, a winter annual, is a relatively poor host of AMF. This shift is likely intertwined with decreased carbon (C)-sequestration in cheatgrass-invaded soils and alterations in overall soil fungal community composition and structure, but the latter remain unresolved. We examined soil fungal communities using high throughput amplicon sequencing (ribosomal large subunit gene) in the 0-4 cm and 4-8 cm depth intervals of six cores from cheatgrass- and six cores from sagebrush-dominated soils. Sagebrush core surfaces (0-4 cm) contained higher nitrogen and total C than cheatgrass core surfaces; these differences mirrored the presence of glomalin related soil proteins (GRSP), which has been associated with AMF activity and increased C-sequestration. Fungal richness was not significantly affected by vegetation type, depth or an interaction of the two factors. However, the relative abundance of seven taxonomic orders was significantly affected by vegetation type or the interaction between vegetation type and depth. Teloschistales, Spizellomycetales, Pezizales and Cantharellales were more abundant in sagebrush libraries and contain mycorrhizal, lichenized and basal lineages of fungi. Only two orders (Coniochaetales and Sordariales), which contain numerous economically important pathogens and opportunistic saprotrophs, were more abundant in cheatgrass libraries. Pleosporales, Agaricales, Helotiales and Hypocreales were most abundant across all libraries, but the number of genera detected within these orders was as much as 29 times lower in cheatgrass relative to sagebrush libraries. These compositional differences between fungal communities associated with cheatgrass- and

  11. Relative abundance of and composition within fungal orders differ between cheatgrass (Bromus tectorum) and sagebrush (Artemisia tridentata)-associated soils.

    PubMed

    Wiber, Carolyn F; King, Gary M; Aho, Ken

    2015-01-01

    Nonnative Bromus tectorum (cheatgrass) is decimating sagebrush steppe, one of the largest ecosystems in the Western United States, and is causing regional-scale shifts in the predominant plant-fungal interactions. Sagebrush, a native perennial, hosts arbuscular mycorrhizal fungi (AMF), whereas cheatgrass, a winter annual, is a relatively poor host of AMF. This shift is likely intertwined with decreased carbon (C)-sequestration in cheatgrass-invaded soils and alterations in overall soil fungal community composition and structure, but the latter remain unresolved. We examined soil fungal communities using high throughput amplicon sequencing (ribosomal large subunit gene) in the 0-4 cm and 4-8 cm depth intervals of six cores from cheatgrass- and six cores from sagebrush-dominated soils. Sagebrush core surfaces (0-4 cm) contained higher nitrogen and total C than cheatgrass core surfaces; these differences mirrored the presence of glomalin related soil proteins (GRSP), which has been associated with AMF activity and increased C-sequestration. Fungal richness was not significantly affected by vegetation type, depth or an interaction of the two factors. However, the relative abundance of seven taxonomic orders was significantly affected by vegetation type or the interaction between vegetation type and depth. Teloschistales, Spizellomycetales, Pezizales and Cantharellales were more abundant in sagebrush libraries and contain mycorrhizal, lichenized and basal lineages of fungi. Only two orders (Coniochaetales and Sordariales), which contain numerous economically important pathogens and opportunistic saprotrophs, were more abundant in cheatgrass libraries. Pleosporales, Agaricales, Helotiales and Hypocreales were most abundant across all libraries, but the number of genera detected within these orders was as much as 29 times lower in cheatgrass relative to sagebrush libraries. These compositional differences between fungal communities associated with cheatgrass- and

  12. Assessing Cheatgrass (Bromus tectorum) genetic diversity and population structure using RAPD and microsatellite molecular markers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Two molecular marker systems, random amplified polymorphic DNA (RAPD) and microsatellites, were used to evaluate population diversity and differentiation in four northern Nevada Bromus tectorum populations. We found 16 RAPD primers that yielded 165 strong repeatable bands. Of those bands, 60 (35.8%...

  13. A comparision of cumulative-germination response of cheatgrass (Bromus Tectorum L.) and five perennial bunchgrass species to simulated field-temperature regimes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cheatgrass (Bromus tectorum L.) has come to dominate millions of hectares of rangeland in the Intermountain western United States. Previous studies have hypothesized that one mechanism conferring a competitive advantage to this species is the ability to germinate rapidly at low temperatures in the ...

  14. Bromus tectorum: Variation in Seed Dormancy Among Populations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cheatgrass (Bromus tectorum) is an exotic invasive annual grass that has invaded millions of hectares of rangelands throughout the west. The introduction and invasion of cheatgrass has increased the chance, rate and spread of wildfires. Cheatgrass truncates secondary succession as it outcompetes nat...

  15. NITROGEN ENHANCES THE COMPETITIVE ABILITY OF CHEATGRASS(BROMUS TECTORUM) RELATIVE TO NATIVE GRASSES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Invasion by cheatgrass and the associated high fire frequency can displace native plant communities. Previous native plant restoration projects have met with limited success. Manipulating soil resources may be one component of influencing the success of restoration efforts. We conducted two ...

  16. Effects of repeated burning of cheatgrass (Bromus tectorum) dominated ecosystems on litter, soil and plant nitrogen: Implications for restoration

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Provide electronically in Word. Background/Question/Methods Restoration of cheatgrass-dominated rangelands depends on controlling cheatgrass while simultaneously providing conditions necessary for native species establishment. Growth and reproduction of cheatgrass is highly responsive to available s...

  17. Effects of repeated burning of cheatgrass (Bromus tectorum) dominated ecosystems on plant density, biomass and seed production: Implications for restoration

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Restoration of sagebrush ecosystems dominated by cheatgrass depends on both controlling the invader and providing the conditions for native species establishment. Reducing available soil nitrogen (N) decreases cheatgrass growth and reproduction and native species opportunities for establishment. A m...

  18. Forecasting Bromus tectorum and fire threat: site soil type versus population traits

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cheatgrass (Bromus tectorum), is an exotic invasive annual grass that increases the chance, rate, spread and season of wildfires. Cheatgrass truncates secondary succession by out-competing native perennial seedlings for limited moisture and resources. Habitats that historically burned every 60-110...

  19. Suppression of Bromus tectorum L. by established perennial grasses: mechanisms-Part One

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bromus tectorum L. (cheatgrass) is an Eurasian annual grass that has invaded ecosystems throughout the Intermountain west of the United States. Our purpose was to examine mechanisms by which established perennial grasses suppress the growth of B. tectorum. Using rhizotrons, the experiment was conduc...

  20. BIOGEOCHEMISTRY OF PLANT INVASION: A CASE STUDY WITH BROMUS TECTORUM L.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The exotic invasive annual grass Bromus tectorum L. (cheatgrass) is problematic in the intermountain region of the western United States, often replacing native shrub/perennial grass communities with near monocultures. Limited data exists on the affect of B. tectorum invasion on biogeochemical cycli...

  1. Effect of Competition with Perennial Grasses on the Growth and Nutrient Concentrations of Bromus tectorum L.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We investigated the effect of established perennial plants on growth of the invasive annual grass Bromus tectorum L. (cheatgrass, downy brome). Seeds of B. tectorum were planted between two established plants (competition) and individually (no competition) in separate (4 replicates) rhizotrons (30 c...

  2. Plant-Soil Relationships of Bromus tectorum L.: Interactions among Labile Carbon Additions, Soil Invasion Status, and Fertilizer.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Invasion of western North America by the annual exotic grass Bromus tectorum L. (cheatgrass) has been an ecological disaster. High soil bioavailability of nitrogen is a contributing factor in the invasive potential of B. tectorum. Application of labile carbon sources to the soil can immobilize soil ...

  3. Bromus tectorum L. invasion: Changes in soil properties and rates of bioturbation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bromus tectorum (cheatgrass, downy brome), an exotic annual grass of Eurasian origin, has replaced native Artemisia/bunchgrass communities on millions of hectares throughout the Intermountain West. Using Jenny’s (1941) framework that specific vegetation can differentially affect soil development; we...

  4. The effect of annual precipitation on Agropyron cristatum suppression of bromus tectorum

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The ability of established crested wheatgrass (Agropyron cristatum) to suppress cheatgrass (Bromus tectorum) is well documented. Many studies that examine the competition between these two species usually do so at the seedling phase. We do not consider decreased performance between two seedlings as ...

  5. Defoliation effects on Bromus tectorum seed production: Implications for grazing

    USGS Publications Warehouse

    Hempy-Mayer, K.; Pyke, D.A.

    2008-01-01

    Cheatgrass (Bromus tectorum L.) is an invasive annual grass that creates near-homogenous stands in areas throughout the Intermountain sagebrush steppe and challenges successful native plant restoration in these areas. A clipping experiment carried out at two cheatgrass-dominated sites in eastern Oregon (Lincoln Bench and Succor Creek) evaluated defoliation as a potential control method for cheatgrass and a seeding preparation method for native plant reseeding projects. Treatments involved clipping plants at two heights (tall = 7.6 cm, and short = 2.5 cm), two phenological stages (boot and purple), and two frequencies (once and twice), although purple-stage treatments were clipped only once. Treatments at each site were replicated in a randomized complete block design that included a control with no defoliation. End-of-season seed density (seeds??m-2) was estimated by sampling viable seeds from plants, litter, and soil of each treatment. Undipped control plants produced an average of approximately 13 000 and 20 000 seeds??m-2 at Lincoln Bench and Succor Creek, respectively. Plants clipped short at the boot stage and again 2 wk later had among the lowest mean seed densities at both sites, and were considered the most successful treatments (Lincoln Bench: F 6,45 = 47.07, P < 0.0001; Succor Creek: F6,40 = 19.60, P < 0.0001). The 95% confidence intervals for seed densities were 123-324 seeds??m-2 from the Lincoln Bench treatment, and 769-2256 seeds??m-2 from the Succor Creek treatment. Literature suggests a maximum acceptable cheatgrass seed density of approximately 330 seeds??m-2 for successful native plant restoration through reseeding. Thus, although this study helped pinpoint optimal defoliation parameters for cheatgrass control, it also called into question the potential for livestock grazing to be an effective seed-bed preparation technique in native plant reseeding projects in cheatgrass-dominated areas.

  6. Environmental and climatic variables as potential drivers of post-fire cover of cheatgrass (Bromus tectorum) in seeded and unseeded semiarid ecosystems

    USGS Publications Warehouse

    Shinneman, D.J.; Baker, W.L.

    2009-01-01

    Cheatgrass, a non-native annual grass, dominates millions of hectares in semiarid ecosystems of the Intermountain West (USA). Post-fire invasions can reduce native species diversity and alter ecological processes. To curb cheatgrass invasion, land managers often seed recently burned areas with perennial competitor species. We sampled vegetation within burned (19 years post-fire) and nearby unburned (representing pre-fire) pionjuniper (Pinus edulisJuniperus osteosperma) woodland and sagebrush (Artemisia sp.) in western Colorado to analyze variables that might explain cheatgrass cover after fire. A multiple regression model suggests higher cheatgrass cover after fire with: (1) sagebrush v. pionjuniper; (2) higher pre-fire cover of annual forbs; (3) increased time since fire; (4) lower pre-fire cover of biological soil crust; and (5) lower precipitation the year before fire. Time since fire, which coincided with higher precipitation, accounts for most of the variability in cheatgrass cover. No significant difference was found in mean cheatgrass cover between seeded and unseeded plots over time. However, negative relationships with pre-fire biological soil crust cover and native species richness suggest livestock-degraded areas are more susceptible to post-fire invasion. Proactive strategies for combating cheatgrass should include finding effective native competitors and restoring livestock-degraded areas. ?? 2009 IAWF.

  7. A mutualistic interaction between a fungivorous nematode and a fungus within the endophytic community of Bromus tectorum

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In its invaded range in western North America, Bromus tectorum can host more than 100 sequence-based phylotypes of endophytic fungi of which an individual cheatgrass plant hosts a subset. In general, research suggests that recruitment of a particular subset of endophytes by an individual plant will...

  8. Cheatgrass invasion and wildlife habitat

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The introduction and subsequent invasion of cheatgrass (Bromus tectorum) has altered native plant communities and the wildlife species that depend on these communities. Cheatgrass has truncated secondary succession by outcompeting native plant species for limited resources, thus building persistent...

  9. Rehabilitation of cheatgrass infested rangelands

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The introduction and subsequent invasion of cheatgrass (Bromus tectorum) has altered native plant communities and the wildlife species that depend on these communities. Cheatgrass has truncated secondary succession by outcompeting native plant species for limited resources, thus building persistent...

  10. Rehabilitation of cheatgrass-infested rangelands

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The introduction and subsequent invasion of cheatgrass (Bromus tectorum) has altered native plant communities and the wildlife species that depend on these communities. Cheatgrass has truncated secondary succession by outcompeting native plant species for limited resources, thus building persistent...

  11. Conditions favouring Bromus tectorum dominance of endangered sagebrush steppe ecosystems

    USGS Publications Warehouse

    Reisner, Michael D.; Grace, James B.; Pyke, David A.; Doescher, Paul S.

    2013-01-01

    4. Synthesis and applications. Grazing exacerbates Bromus tectorum dominance in one of North America's most endangered ecosystems by adversely impacting key mechanisms mediating resistance to invasion. If the goal is to conserve and restore resistance of these systems, managers should consider maintaining or restoring: (i) high bunchgrass cover and structure characterized by spatially dispersed bunchgrasses and small gaps between them; (ii) a diverse assemblage of bunchgrass species to maximize competitive interactions with B. tectorum in time and space; and (iii) biological soil crusts to limit B. tectorum establishment. Passive restoration by reducing cumulative cattle grazing may be one of the most effective means of achieving these three goals.

  12. Rehabilitation of cheatgrass infested rangelands: an integrated approach

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cheatgrass (Bromus tectorum) invasion has astronomically altered native plant communities throughout the Intermountain West. Cheatgrass has truncated secondary succession by outcompeting native plant species for limited resources, thus building persistent seed banks to take advantage of conditions ...

  13. Effects of precipitation change and neighboring plants on population dynamics of Bromus tectorum.

    PubMed

    Prevéy, Janet S; Seastedt, Timothy R

    2015-11-01

    Shifting precipitation patterns resulting from global climate change will influence the success of invasive plant species. In the Front Range of Colorado, Bromus tectorum (cheatgrass) and other non-native winter annuals have invaded grassland communities and are becoming more abundant. As the global climate warms, more precipitation may fall as rain rather than snow in winter, and an increase in winter rain could benefit early-growing winter annuals, such as B. tectorum, to the detriment of native species. In this study we measured the effects of simulated changes in seasonal precipitation and presence of other plant species on population growth of B. tectorum in a grassland ecosystem near Boulder, Colorado, USA. We also performed elasticity analyses to identify life transitions that were most sensitive to precipitation differences. In both study years, population growth rates were highest for B. tectorum growing in treatments receiving supplemental winter precipitation and lowest for those receiving the summer drought treatment. Survival of seedlings to flowering and seed production contributed most to population growth in all treatments. Biomass of neighboring native plants was positively correlated with reduced population growth rates of B. tectorum. However, exotic plant biomass had no effect on population growth rates. This study demonstrates how interacting effects of climate change and presence of native plants can influence the population growth of an invasive species. Overall, our results suggest that B. tectorum will become more invasive in grasslands if the seasonality of precipitation shifts towards wetter winters and allows B. tectorum to grow when competition from native species is low. PMID:26227366

  14. Drought survival and perennial grass success in the face of cheatgrass invasion: germination, emergence, seedling die-off and reproduction

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cheatgrass (Bromus tectorum) dominance and competitiveness is often attributed to early (fall) germination. We hypothesize that cheatgrass germinates earlier compared to three commonly used restoration/rehabilitation perennial grass species [‘Hycrest’ crested wheatgrass( Agropyron desertorum ssp. c...

  15. Using high-resolution future climate scenarios to forecast Bromus tectorum invasion in Rocky Mountain National Park.

    PubMed

    West, Amanda M; Kumar, Sunil; Wakie, Tewodros; Brown, Cynthia S; Stohlgren, Thomas J; Laituri, Melinda; Bromberg, Jim

    2015-01-01

    National Parks are hallmarks of ecosystem preservation in the United States. The introduction of alien invasive plant species threatens protection of these areas. Bromus tectorum L. (commonly called downy brome or cheatgrass), which is found in Rocky Mountain National Park (hereafter, the Park), Colorado, USA, has been implicated in early spring competition with native grasses, decreased soil nitrogen, altered nutrient and hydrologic regimes, and increased fire intensity. We estimated the potential distribution of B. tectorum in the Park based on occurrence records (n = 211), current and future climate, and distance to roads and trails. An ensemble of six future climate scenarios indicated the habitable area of B. tectorum may increase from approximately 5.5% currently to 20.4% of the Park by the year 2050. Using ordination methods we evaluated the climatic space occupied by B. tectorum in the Park and how this space may shift given future climate change. Modeling climate change at a small extent (1,076 km2) and at a fine spatial resolution (90 m) is a novel approach in species distribution modeling, and may provide inference for microclimates not captured in coarse-scale models. Maps from our models serve as high-resolution hypotheses that can be improved over time by land managers to set priorities for surveys and removal of invasive species such as B. tectorum. PMID:25695255

  16. Using High-Resolution Future Climate Scenarios to Forecast Bromus tectorum Invasion in Rocky Mountain National Park

    PubMed Central

    West, Amanda M.; Kumar, Sunil; Wakie, Tewodros; Brown, Cynthia S.; Stohlgren, Thomas J.; Laituri, Melinda; Bromberg, Jim

    2015-01-01

    National Parks are hallmarks of ecosystem preservation in the United States. The introduction of alien invasive plant species threatens protection of these areas. Bromus tectorum L. (commonly called downy brome or cheatgrass), which is found in Rocky Mountain National Park (hereafter, the Park), Colorado, USA, has been implicated in early spring competition with native grasses, decreased soil nitrogen, altered nutrient and hydrologic regimes, and increased fire intensity. We estimated the potential distribution of B. tectorum in the Park based on occurrence records (n = 211), current and future climate, and distance to roads and trails. An ensemble of six future climate scenarios indicated the habitable area of B. tectorum may increase from approximately 5.5% currently to 20.4% of the Park by the year 2050. Using ordination methods we evaluated the climatic space occupied by B. tectorum in the Park and how this space may shift given future climate change. Modeling climate change at a small extent (1,076 km2) and at a fine spatial resolution (90 m) is a novel approach in species distribution modeling, and may provide inference for microclimates not captured in coarse-scale models. Maps from our models serve as high-resolution hypotheses that can be improved over time by land managers to set priorities for surveys and removal of invasive species such as B. tectorum. PMID:25695255

  17. Positive effects of native shrubs on Bromus tectorum demography.

    PubMed

    Griffith, Alden B

    2010-01-01

    There is increasing recognition that overall interactions among plant species are often the net result of both positive and negative effects. However, the positive influence of other plants has rarely been examined using detailed demographic methods, which are useful for partitioning net effects at the population level into positive and/or negative effects on individual vital rates. This study examines the influence of microhabitats created by the native shrubs Artemisia tridentata and Purshia tridentata on the demography of the invasive annual grass Bromus tectorum in the Great Basin Desert, California, USA. Shrub understory environments differed significantly from intershrub space and were characterized by higher soil fertility and less extreme microclimates. There existed a strong spatial association between B. tectorum and the shrubs across four years, with more than double the density of B. tectorum in shrub microhabitats compared to intershrub space. Periodic matrix models were used to calculate population growth (lamda) and reproductive potential (RP, expected lifetime fecundity of seedlings) of B. tectorum in different microhabitats over two years. Modeled population growth was significantly increased in shrub microhabitats in the first of two years. This was primarily due to increased seedling establishment in Artemisia microhabitats, rather than effects during the growing season. In the following year, B. tectorum individuals in shrub microhabitats had a significantly greater reproductive potential than those in intershrub microhabitats, indicating shrub facilitation during the growing season. Loop analysis revealed an interacting effect of year and microhabitat on B. tectorum life history pathway elasticity values, demonstrating a fundamental influence of spatiotemporal factors on which life history pathways are important and/or possible. Life table response experiment (LTRE) analysis showed that increased survival and growth rates positively contributed

  18. Cheatgrass

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cheatgrass (Bromus tectorm) was first introduced into the Intermountain west in the early 1900's. Cheatgrass truncates secondary succession by out competing native perennial grass seedlings for limited resources and then providing an early maturing, fine textured fuel that increases the chance, rat...

  19. Cheatgrass Response to Simulated Grazing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    At the very time of this writing we are looking out at a plume of smoke from a cheatgrass (Bromus tectorum) fueled wildfire. These cheatgrass fueled wildfires are an annual event here in Nevada as well as other arid western states, and thus the topic seems fitting to write about. This annual burni...

  20. Imazapic, rimsulfuron, and sulfometuron methyl effectiveness at controlling cheatgrass

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The introduction and subsequent invasion of cheatgrass (Bromus tectorum) onto Intermountain rangelands has resulted in increased frequencies of wildfires and severely altered native plant communities. These destructive wildfires have negatively impacted wildlife and grazing resources. The ability o...

  1. Perennial grass establishment following cheatgrass control using herbicides

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The introduction and subsequent invasion of Cheatgrass (Bromus tectorum) onto Intermountain rangelands has resulted in increased frequencies of wildfires and severely altered native plant communities. These destructive wildfires have negatively impacted wildlife and grazing resources as well as har...

  2. Soil sterilization alters interactions between the native grass Bouteloua gracilis and invasive Bromus tectorum

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aims: The invasive grass Bromus tectorum negatively impacts grassland communities throughout the western U.S. We asked whether soil biota growing in association with a native grass (Bouteloua gracilis) increase growth and competitive ability of Bromus, and whether responses vary between soils collec...

  3. Soil amendment effects on the exotic annual grass Bromus tectorum L. and facilitation of its growth by the native perennial grass Hilaria jamesii (Torr.) Benth

    USGS Publications Warehouse

    Belnap, J.; Sherrod, S.K.

    2009-01-01

    Greenhouse experiments were undertaken to identify soil factors that curtail growth of the exotic annual grass Bromus tectorum L. (cheatgrass) without significantly inhibiting growth of native perennial grasses (here represented by Hilaria jamesii [Torr.] Benth). We grew B. tectorum and H. jamesii alone (monoculture pots) and together (combination pots) in soil treatments that manipulated levels of soil phosphorus, potassium, and sodium. Hilaria jamesii showed no decline when its aboveground biomass in any of the applied treatments was compared to the control in either the monoculture or combination pots. Monoculture pots of B. tectorum showed a decline in aboveground biomass with the addition of Na2HPO4 and K2HPO4. Interestingly, in pots where H. jamesii was present, the negative effect of these treatments was ameliorated. Whereas the presence of B. tectorum generally decreased the aboveground biomass of H. jamesii (comparing aboveground biomass in monoculture versus combination pots), the presence of H. jamesii resulted in an enhancement of B. tectorum aboveground biomass by up to 900%. We hypothesize that B. tectorum was able to obtain resources from H. jamesii, an action that benefited B. tectorum while generally harming H. jamesii. Possible ways resources may be gained by B. tectorum from native perennial grasses include (1) B. tectorum is protected from salt stress by native plants or associated soil biota; (2) when B. tectorum is grown with H. jamesii, the native soil biota is altered in a way that favors B. tectorum growth, including B. tectorum tapping into the mycorrhizal network of native plants and obtaining resources from them; (3) B. tectorum can take advantage of root exudates from native plants, including water and nutrients released by natives via hydraulic redistribution; and (4) B. tectorum is able to utilize some combination of the above mechanisms. In summary, land managers may find adding soil treatments can temporarily suppress B. tectorum

  4. Phenology of cheatgrass and associated exotic weeds

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cheatgrass (Bromus tectorum), is an exotic, highly invasive annual grass that has dramatically changed the aspect and ecological functions of vast areas of formerly big sagebrush/bunchgrass and salt desert rangelands in the Intermountain west. Cheatgrass increases the chance of ignition, rate of spr...

  5. Cheatgrass germination at three seed maturity stages from five plant communities in northwestern Nevada

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The invasive exotic plant cheatgrass (Bromus tectorum), has invaded numerous plant communities throughout the Intermountain West. Our goal was to test whether cheatgrass seed in different phenotypic stages and site characteristics differ in germination. Cheatgrass seed from sites dominated by Wyom...

  6. The development of water stress in Bromus tectorum and Poa secunda in the field

    SciTech Connect

    Link, S.O.; Downs, J.L.; Gee, G.W.

    1987-03-01

    Field observations of the phenological development, root and shoot characteristics, and water relations with increasing water stress of Bromus tectorum and Poa secunda were compared. The phenological development of B. tectorum was 3 to 4 weeks behind that of P. secunda. The root/shoot ratio of B. tectorum was 4 to 5 times less than that of P secunda. The greatest rooting depth was 45 cm for B. tectorum and 35 cm for P. secunda. Most of the root mass was found in the top 10 cm of soil for both species. Water stress developed sooner and to a greater degree in P. secunda than in B. tectorum. Xylem water potential was lower in P. secunda than in B. tectorum and the difference increased through the season. Pre-dawn xylem water potential was highly correlated with maximal stomatal conductance in P. secunda. Hydraulic conductance was greater in B. tectorum than in P. secunda, and decreased as water stress increased through the season. Stomatal conductance and transpiration were greater for B. tectorum than for P. secunda. Midday stomatal closure occurred later in the season and to a lesser degree for B. tectorum than for P. secunda. 31 refs., 7 figs., 1 tab.

  7. Soil nitrogen enhances the competitive ability of Bromus tectorum relative to native grasses

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Invasion by Bromus tectorum and the associated high fire frequency can displace native plant communities. Previous native plant restoration projects have met with limited success. Manipulating soil resources may be one way of influencing the success of restoration efforts. We conducted two greenh...

  8. Do soil characteristics or microhabitat determine field emergence and success of Bromus tectorum?

    USGS Publications Warehouse

    Newingham, B.A.; Vidiella, P.; Belnap, J.

    2007-01-01

    In southeastern Utah, Bromus tectorum occurs where Hilaria jamesii is dominant and rarely where Stipa hymenoides/S. comata dominate. To determine whether this distribution is due to soil characteristics or microhabitat, we transplanted H. jamesii soil to a Stipa site and vice versa during a severe drought (2001) and a wetter year (2002). Additionally, we planted B. tectorum under H. jamesii and Stipa canopies, with or without H. jamesii litter, and with or without herbivory. Bromus tectorum emergence and biomass in reciprocal transplants were similar at both sites; there were no site differences for all microhabitat treatments. Being under a plant canopy increased emergence in 2001 and decreased survival during 2002. Herbivory decreased emergence in 2001 and decreased survival during 2002. Litter increased emergence only under the canopy in 2001 but did not affect survival in 2002. Survival in 2001 was so low that biomass was unattainable; no microhabitat treatments affected biomass in 2002. We found that soil characteristics and microhabitat affected B. tectorum similarly in H. jamesii and Stipa patches, suggesting that these factors do not explain the association between B. tectorum and H. jamesii. However, these relationships may change during wet years when B. tectorum invasions most often occur. ?? 2006 Elsevier Ltd. All rights reserved.

  9. Integrated approach to cheatgrass suppression on great basin rangelands

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cheatgrass (Bromus tectorum), native to central Eurasia, is a highly invasive annual grass that has invaded millions of hectares of rangelands throughout the Intermountain West. Cheatgrass has revolutionized secondary succession by providing a fine-textured, early-maturing fuel that increases the c...

  10. The effect of discing to reduce cheatgrass competition following wildfires

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wildfires in the Intermountain West are and annual event. The introduction and subsequent invasion of cheatgrass (Bromus tectorum) onto millions of acres of rangelands throughout the West has resulted in devastating wildfires. Cheatgrass truncates secondary succession by out competing native peren...

  11. Integrated approach to cheatgrass suppression on Great Basin Rangelands

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cheatgrass (Bromus tectorum), native to central Eurasia, is a highly invasive annual grass that has invaded millions of hectares of rangelands throughout the Intermountain West. Cheatgrass has revolutionized secondary succession by providing a fine-textured, early-maturing fuel that increases the c...

  12. The use of plant material testing to successfully suppress cheatgrass

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cheatgrass (Bromus tectorum) is an exotic and invasive annual grass that was accidentally introduced to western North America in the late 19th century. Cheatgrass provides an early maturing, fine-textured fuel that increases the chance, rate, spread and season of wildfires. With each passing wildfi...

  13. Interactions with soils conditioned by different vegetation: A potential explanation of Bromus tectorum L. invasion into salt-deserts?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Invasion by Bromus tectorum L. may condition the soil and increase nutrient availability. We hypothesized that nutrient poor soils of the arid Honey Lake Valley of northeastern California U.S.A., similar in physical and chemical properties, but conditioned by either B. tectorum, Krascheninniko...

  14. Interactions with soils conditioned by different vegetation: a potential explanation of bromus tectorum L. invasion into salt-deserts?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Invasion by Bromus tectorum L. may condition the soil and increase nutrient availability. We hypothesized that nutrient poor soils of the arid Honey Lake Valley of northeastern California U.S.A., similar in physical and chemical properties, but conditioned by either B. tectorum, Krascheninniko...

  15. Global change effects on Bromus tectorum L. (Poaceae) at its high-elevation range margin

    USGS Publications Warehouse

    Concilio, Amy L.; Loik, Michael E.; Belnap, Jayne

    2013-01-01

    Global change is likely to affect invasive species distribution, especially at range margins. In the eastern Sierra Nevada, California, USA, the invasive annual grass, Bromus tectorum, is patchily distributed and its impacts have been minimal compared with other areas of the Intermountain West. We used a series of in situ field manipulations to determine how B. tectorum might respond to changing climatic conditions and increased nitrogen deposition at the high-elevation edge of its invaded range. Over 3 years, we used snow fences to simulate changes in snowpack, irrigation to simulate increased frequency and magnitude of springtime precipitation, and added nitrogen (N) at three levels (0, 5, and 10 g m-2) to natural patches of B. tectorum growing under the two dominant shrubs, Artemisia tridentata and Purshia tridentata, and in intershrub spaces (INTR). We found that B. tectorum seedling density in April was lower following deeper snowpack possibly due to delayed emergence, yet there was no change in spikelet production or biomass accumulation at the time of harvest. Additional spring rain events increased B. tectorum biomass and spikelet production in INTR plots only. Plants were primarily limited by water in 2009, but colimited by N and water in 2011, possibly due to differences in antecedent moisture conditions at the time of treatments. The threshold at which N had an effect varied with magnitude of water additions. Frequency of rain events was more influential than magnitude in driving B. tectorum growth and fecundity responses. Our results suggest that predicted shifts from snow to rain could facilitate expansion of B. tectorum at high elevation depending on timing of rain events and level of N deposition. We found evidence for P-limitation at this site and an increase in P-availability with N additions, suggesting that stoichiometric relationships may also influence B. tectorum spread.

  16. Eco-evolutionary responses of Bromus tectorum to climate change: implications for biological invasions

    PubMed Central

    Zelikova, Tamara J; Hufbauer, Ruth A; Reed, Sasha C; Wertin, Timothy; Fettig, Christa; Belnap, Jayne

    2013-01-01

    How plant populations, communities, and ecosystems respond to climate change is a critical focus in ecology today. The responses of introduced species may be especially rapid. Current models that incorporate temperature and precipitation suggest that future Bromus tectorum invasion risk is low for the Colorado Plateau. With a field warming experiment at two sites in southeastern Utah, we tested this prediction over 4 years, measuring B. tectorum phenology, biomass, and reproduction. In a complimentary greenhouse study, we assessed whether changes in field B. tectorum biomass and reproductive output influence offspring performance. We found that following a wet winter and early spring, the timing of spring growth initiation, flowering, and summer senescence all advanced in warmed plots at both field sites and the shift in phenology was progressively larger with greater warming. Earlier green-up and development was associated with increases in B. tectorum biomass and reproductive output, likely due early spring growth, when soil moisture was not limiting, and a lengthened growing season. Seeds collected from plants grown in warmed plots had higher biomass and germination rates and lower mortality than seeds from ambient plots. However, in the following two dry years, we observed no differences in phenology between warmed and ambient plots. In addition, warming had a generally negative effect on B. tectorum biomass and reproduction in dry years and this negative effect was significant in the plots that received the highest warming treatment. In contrast to models that predict negative responses of B. tectorum to warmer climate on the Colorado Plateau, the effects of warming were more nuanced, relied on background climate, and differed between the two field sites. Our results highlight the importance of considering the interacting effects of temperature, precipitation, and site-specific characteristics such as soil texture, on plant demography and have direct

  17. Eco-evolutionary responses of Bromus tectorum to climate change: implications for biological invasions

    USGS Publications Warehouse

    Zelikova, Tamara J.; Hufbauer, Ruth A.; Reed, Sasha C.; Wertin, Timothy M.; Fettig, Christa; Belnap, Jayne

    2013-01-01

    How plant populations, communities, and ecosystems respond to climate change is a critical focus in ecology today. The responses of introduced species may be especially rapid. Current models that incorporate temperature and precipitation suggest that future Bromus tectorum invasion risk is low for the Colorado Plateau. With a field warming experiment at two sites in southeastern Utah, we tested this prediction over 4 years, measuring B. tectorum phenology, biomass, and reproduction. In a complimentary greenhouse study, we assessed whether changes in field B. tectorum biomass and reproductive output influence offspring performance. We found that following a wet winter and early spring, the timing of spring growth initiation, flowering, and summer senescence all advanced in warmed plots at both field sites and the shift in phenology was progressively larger with greater warming. Earlier green-up and development was associated with increases in B. tectorum biomass and reproductive output, likely due early spring growth, when soil moisture was not limiting, and a lengthened growing season. Seeds collected from plants grown in warmed plots had higher biomass and germination rates and lower mortality than seeds from ambient plots. However, in the following two dry years, we observed no differences in phenology between warmed and ambient plots. In addition, warming had a generally negative effect on B. tectorum biomass and reproduction in dry years and this negative effect was significant in the plots that received the highest warming treatment. In contrast to models that predict negative responses of B. tectorum to warmer climate on the Colorado Plateau, the effects of warming were more nuanced, relied on background climate, and differed between the two field sites. Our results highlight the importance of considering the interacting effects of temperature, precipitation, and site-specific characteristics such as soil texture, on plant demography and have direct

  18. Plant material testing and cheatgrass suppression: a 10 year old case study

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cheatgrass (Bromus tectorum) is an exotic and invasive annual grass that was accidentally introduced to western North America in the late 19th century. Cheatgrass soon spread across millions of hectares of Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis)/ bunchgrass rangelands througho...

  19. Morphological and physiological traits account for similar nitrate uptake by crested wheatgrass and cheatgrass

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Millions of hectares throughout the Intermountain West are either dominated or threatened by the invasive annual grass Bromus tectorum (cheatgrass). This invasion is largely linked to disturbance and few regions appear immune. Disturbance liberates resources in a community and cheatgrass appears e...

  20. SOIL MORPHOLOGY AND ORGANIC MATTER DYNAMICS UNDER CHEATGRASS AND SAGEBRUSH-STEPPE PLANT COMMUNITIES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Widespread cheatgrass (Bromus tectorum L) invasion represents a major shift in species dominance that may alter ecosystem processes across much of the western U.S. To investigate differences following such conversion, soil morphology and organic matter under cheatgrass-dominated and native shrub-st...

  1. Cheatgrass is favored by warming but not CO2 enrichment in a semi-arid grassland

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Global change impacts may be compounded by invasive species with strong community and ecosystem impacts. Bromus tectorum (cheatgrass) increases fire frequency and reduces biological diversity across millions of hectares in western North America. Here we show that B. tectorum recruitment, growth and ...

  2. Inter- and intra-specific interactions in germination and seedling establishment of cheatgrass and Russian wildrye

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cheatgrass (Bromus tectorum L.) growth has been shown to be affected by soil type and soil borne pathogens. In this experiment, I test if competitive relationships between B. tectorum and Russian wild rye (Psathryrostachys juncea (Fisch.) Nevski) are different in three soil types. Soils were collect...

  3. Rehabilitation of cheatgrass-infested rangelands: concepts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The introduction and subsequent invasion of cheatgrass (Bromus tectorum) onto millions of acres of Intermountain West rangelands has caused astronomical changes to numerous ecosystems and the multiple uses that depend on healthy and functional ecosystems. This is the first part, of a 3-part series ...

  4. Suppression of annual Bromus tectorum by perennial Agropyon cristatum: roles of soil N availability and biological soil space

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Worldwide, exotic invasive grasses have caused numerous ecosystem perturbations. Rangelands of the western United States have experienced increases in the size and frequency of wildfires largely due to invasion by the annual grass Bromus tectorum. Rehabilitation of invaded rangelands is difficult; b...

  5. Control of Downy brome (Bromus tectorum) and Medusahead (Teaniatherum caput-medusae) with Rangeland Herbicides in Northeastern California.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Downy brome (Bromus tectorum) and medusahead ((Teaniatherum caput-medusae) are the two most problematic invasive annual grasses in the western United States. In this study we evaluated the effect of three fall and one spring application of herbicide as well as herbicide combinations on the control ...

  6. Interacting Agricultural Pests and Their Effect on Crop Yield: Application of a Bayesian Decision Theory Approach to the Joint Management of Bromus tectorum and Cephus cinctus

    PubMed Central

    Keren, Ilai N.; Menalled, Fabian D.; Weaver, David K.; Robison-Cox, James F.

    2015-01-01

    Worldwide, the landscape homogeneity of extensive monocultures that characterizes conventional agriculture has resulted in the development of specialized and interacting multitrophic pest complexes. While integrated pest management emphasizes the need to consider the ecological context where multiple species coexist, management recommendations are often based on single-species tactics. This approach may not provide satisfactory solutions when confronted with the complex interactions occurring between organisms at the same or different trophic levels. Replacement of the single-species management model with more sophisticated, multi-species programs requires an understanding of the direct and indirect interactions occurring between the crop and all categories of pests. We evaluated a modeling framework to make multi-pest management decisions taking into account direct and indirect interactions among species belonging to different trophic levels. We adopted a Bayesian decision theory approach in combination with path analysis to evaluate interactions between Bromus tectorum (downy brome, cheatgrass) and Cephus cinctus (wheat stem sawfly) in wheat (Triticum aestivum) systems. We assessed their joint responses to weed management tactics, seeding rates, and cultivar tolerance to insect stem boring or competition. Our results indicated that C. cinctus oviposition behavior varied as a function of B. tectorum pressure. Crop responses were more readily explained by the joint effects of management tactics on both categories of pests and their interactions than just by the direct impact of any particular management scheme on yield. In accordance, a C. cinctus tolerant variety should be planted at a low seeding rate under high insect pressure. However as B. tectorum levels increase, the C. cinctus tolerant variety should be replaced by a competitive and drought tolerant cultivar at high seeding rates despite C. cinctus infestation. This study exemplifies the necessity of

  7. Effects of maternal environment on cheatgrass seed dormancy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    One of the greatest advantages cheatgrass (Bromus tectorum) has is building large seed banks. Seed banks can persist during self dominance, post fire, post herbicidal control and healthy plant communities. There are numerous reasons a seed does not germinate, primarily being a lack of moisture. Howe...

  8. Rehabilitation and Cheatgrass Suppression Following Great Basin Wildfires

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The occurrence of wildfires in Great Basin environments has become an annual event. The introduction and subsequent invasion of cheatgrass (Bromus tectorum) plays a very large role in the frequency and size of these wildfires. With each passing wildfire season, more and more habitats are converted...

  9. Prediction of cheatgrass field germination potential using wet thermal accumulation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Invasion and dominance of weedy species is facilitated or constrained by environmental and ecological factors that affect resource availability during critical life stages. We compared the relative effects of season, annual weather, site, and disturbance on potential cheatgrass (Bromus tectorum L.)...

  10. Cheatgrass suppression following wildfires in Wyoming big sagebrush communities

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The introduction and subsequent invasion of cheatgrass (Bromus tectorum) onto millions of hectares of rangelands throughout the Intermountain West has had devastating effects on a variety of plant communities by promoting a fine textured, early maturing fuel that increases the chance, rate and sprea...

  11. Evidence that invasion by cheatgrass alters soil nitrogen availability

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Certain exotic plant species are known to engineer soil processes and thereby facilitate their competitive stature and invasiveness. In a well-characterized winterfat (Krascheninnikovia lanata) community in the Honey Lake Valley of northeastern CA, we tested if cheatgrass invasion (Bromus tectorum L...

  12. Bromus tectorum invasion alters nitrogen dynamics in an undisturbed arid grassland ecosystem

    USGS Publications Warehouse

    Sperry, L.J.; Belnap, J.; Evans, R.D.

    2006-01-01

    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 surface NH4+ input in spring, whereas there were no differences for surface input of NO3-. Soil inorganic N was dominated by NH4+, but invaded sites had greater subsurface soil NO3-. Invaded sites had greater total soil N at the surface four years post-invasion in undisturbed communities, but total N was lower in the invaded/disturbed communities. Soil ??15N increased with depth in the noninvaded and recently invaded communities, whereas the invaded/disturbed communities exhibited the opposite pattern. Enriched foliar ??15N values suggest that Bromus assimilated subsurface NO3-, whereas the native grasses were restricted to surface N. A Rayleigh distillation model accurately described decomposition patterns in the noninvaded communities where soil N loss is accompanied by increasing soil ??15N; however, the invaded/disturbed communities exhibited the opposite pattern, suggesting redistribution of N within the soil profile. This study suggests that invasion has altered the mechanisms driving nitrogen dynamics. Bromus litter decomposition and soil NO3- concentrations were greater in the invaded communities during periods of ample precipitation, and NO3- leached from the surface litter, where it was assimilated by Bromus. The primary source of N input in these communities is a biological soil crust that is removed with disturbance, and the lack of N input by the biological soil crust did not balance N loss, resulting in reduced total N in the invaded/disturbed communities

  13. Suppression of annual Bromus tectorum by perennial Agropyron cristatum: roles of soil nitrogen availability and biological soil space

    PubMed Central

    Blank, Robert R.; Morgan, Tye; Allen, Fay

    2015-01-01

    Worldwide, exotic invasive grasses have caused numerous ecosystem perturbations. Rangelands of the western USA have experienced increases in the size and frequency of wildfires largely due to invasion by the annual grass Bromus tectorum. Rehabilitation of invaded rangelands is difficult; but long-term success is predicated on establishing healthy and dense perennial grass communities, which suppress B. tectorum. This paper reports on two experiments to increase our understanding of soil factors involved in suppression. Water was not limiting in this study. Growth of B. tectorum in soil conditioned by and competing with the exotic perennial Agropyron cristatum was far less relative to its growth without competition. When competing with A. cristatum, replacing a portion of conditioned soil with fresh soil before sowing of B. tectorum did not significantly increase its growth. The ability of conditioned soil to suppress B. tectorum was lost when it was separated from growing A. cristatum. Soil that suppressed B. tectorum growth was characterized by low mineral nitrogen (N) availability and a high molar ratio of NO2− in the solution-phase pool of NO2−+NO3−. Moreover, resin availability of NO2−+NO3− explained 66 % of the variability in B. tectorum above-ground mass, attesting to the importance of A. cristatum growth in reducing N availability to B. tectorum. Trials in which B. tectorum was suppressed the most were characterized by very high shoot/root mass ratios and roots that have less root hair growth relative to non-suppressed counterparts, suggesting co-opting of biological soil space by the perennial grass as another suppressive mechanism. Greater understanding of the role of biological soil space could be used to breed and select plant materials with traits that are more suppressive to invasive annual grasses. PMID:25603967

  14. Effects of resource availability and propagule supply on native species recruitment in sagebrush ecosystems invaded by Bromus tectorum

    USGS Publications Warehouse

    Mazzola, Monica B.; Chambers, Jeanne C.; Blank, Robert R.; Pyke, David A.; Schupp, Eugene W.; Allcock, Kimberly G.; Doescher, Paul S.; Nowak, Robert S.

    2011-01-01

    Resource availability and propagule supply are major factors influencing establishment and persistence of both native and invasive species. Increased soil nitrogen (N) availability and high propagule inputs contribute to the ability of annual invasive grasses to dominate disturbed ecosystems. Nitrogen reduction through carbon (C) additions can potentially immobilize soil N and reduce the competitiveness of annual invasive grasses. Native perennial species are more tolerant of resource limiting conditions and may benefit if N reduction decreases the competitive advantage of annual invaders and if sufficient propagules are available for their establishment. Bromus tectorum, an exotic annual grass in the sagebrush steppe of western North America, is rapidly displacing native plant species and causing widespread changes in ecosystem processes. We tested whether nitrogen reduction would negatively affect B. tectorum while creating an opportunity for establishment of native perennial species. A C source, sucrose, was added to the soil, and then plots were seeded with different densities of both B. tectorum (0, 150, 300, 600, and 1,200 viable seeds m-2) and native species (0, 150, 300, and 600 viable seeds m-2). Adding sucrose had short-term (1 year) negative effects on available nitrogen and B. tectorum density, biomass and seed numbers, but did not increase establishment of native species. Increasing propagule availability increased both B. tectorum and native species establishment. Effects of B. tectorum on native species were density dependent and native establishment increased as B. tectorum propagule availability decreased. Survival of native seedlings was low indicating that recruitment is governed by the seedling stage.

  15. Effects of Nitrogen Availability and Cheatgrass Competition on the Establishment of Vavilov Siberian Wheatgrass

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cheatgrass (Bromus tectorum L.) is the most widespread invasive weed in the sagebrush ecosystems of North America. Restoration of perennial vegetation is difficult and land managers have often used introduced bunchgrasses to restore these degraded communities. Our objective was to evaluate the poten...

  16. Historical wildfires do not promote cheatgrass invasion in a western Great Plains steppe

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plant invasion and wildfire are often tightly linked. In western North America, positive feedbacks between wildfire and Bromus tectorum (cheatgrass) invasion have contributed to plant community conversion across millions of hectares of land. Impacts of this conversion include reduced biodiversity, w...

  17. Comparison of postfire soil water repellency amelioration strategies on bluebunch wheatgrass and cheatgrass survival

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil water repellency may significantly limit site recovery following wildfire. This study was designed to compare survival and growth of the native plant species bluebunch wheatgrass (Pseudoroegneria spicata (Pursh) A. Löve) to the invasive annual weed cheatgrass (Bromus tectorum L.), and to compar...

  18. Postdispersal Infection and Disease Development of Pyrenophora semeniperda in Bromus tectorum Seeds.

    PubMed

    Finch-Boekweg, Heather; Gardner, John S; Allen, Phil S; Geary, Brad

    2016-03-01

    The Ascomycete fungus, Pyrenophora semeniperda, attacks a broad range of cool-season grasses. While leaf and predispersal infection of seeds (i.e., florets containing caryopses) have been previously characterized, little is known about the pathogenesis of mature seeds following dispersal. In this study, we examined infection and disease development of P. semeniperda on dormant seeds of Bromus tectorum. Inoculated seeds were hydrated at 20°C for up to 28 days. Disease development was characterized using scanning electron and light microscopy. P. semeniperda conidia germinated on the seed surface within 5 to 8 h. Hyphae grew on the seed surface and produced extracellular mucilage that eventually covered the seed. Appressoria formed on the ends of hyphae and penetrated through the lemma and palea, stomatal openings, and broken trichomes. The fungus then catabolized the endosperm, resulting in a visible cavity by 8 days. Pathogenesis of the embryo was associated with progressive loss of cell integrity and proliferation of mycelium. Beginning at approximately day 11, one to several stromata (approximately 150 μm in diameter and up to 4 mm in length) emerged through the lemma and palea. Degradation of embryo tissue was completed near 14 days. Conidiophores produced conidia between 21 and 28 days and often exhibited "Y-shaped" branching. This characterization of disease development corrects previous reports which concluded that P. semeniperda is only a weak seed pathogen with infection limited to the outermost seed tissues. In addition, the time required for disease development explains why infected dormant or slow-germinating seeds are most likely to experience mortality. PMID:26645644

  19. Distributional changes and range predictions of downy brome (Bromus tectorum) in Rocky Mountain National Park

    USGS Publications Warehouse

    Bromberg, J.E.; Kumar, S.; Brown, C.S.; Stohlgren, T.J.

    2011-01-01

    Downy brome (Bromus tectorum L.), an invasive winter annual grass, may be increasing in extent and abundance at high elevations in the western United States. This would pose a great threat to high-elevation plant communities and resources. However, data to track this species in high-elevation environments are limited. To address changes in the distribution and abundance of downy brome and the factors most associated with its occurrence, we used field sampling and statistical methods, and niche modeling. In 2007, we resampled plots from two vegetation surveys in Rocky Mountain National Park for presence and cover of downy brome. One survey was established in 1993 and had been resampled in 1999. The other survey was established in 1996 and had not been resampled until our study. Although not all comparisons between years demonstrated significant changes in downy brome abundance, its mean cover increased nearly fivefold from 1993 (0.7%) to 2007 (3.6%) in one of the two vegetation surveys (P = 0.06). Although the average cover of downy brome within the second survey appeared to be increasing from 1996 to 2007, this slight change from 0.5% to 1.2% was not statistically significant (P = 0.24). Downy brome was present in 50% more plots in 1999 than in 1993 (P = 0.02) in the first survey. In the second survey, downy brome was present in 30% more plots in 2007 than in 1996 (P = 0.08). Maxent, a species-environmental matching model, was generally able to predict occurrences of downy brome, as new locations were in the ranges predicted by earlier generated models. The model found that distance to roads, elevation, and vegetation community influenced the predictions most. The strong response of downy brome to interannual environmental variability makes detecting change challenging, especially with small sample sizes. However, our results suggest that the area in which downy brome occurs is likely increasing in Rocky Mountain National Park through increased frequency and cover

  20. A comparison of Bromus tectorum growth and mycorrhizal colonization in salt desert versus sagebrush habitat

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cheatgrass has recently invaded marginal low elevation salt desert habitats across the Great Basin, USA. We tested the hypothesis that cheatgrass seed produced in populations from the more stressful salt desert versus upland sagebrush habitats should grow differently in salt desert soils compared to...

  1. The role of resource limitation in restoration of sagebrush ecosystems dominated by cheatgrass (Bromus tectorum)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Success of invasive annual grasses is often linked to increases in resources, and restoration ecologists have suggested that decreasing nitrogen (N) availability and restoring more conservative N cycles with lower N turnover should decrease the competitive advantage of these invaders and facilitate ...

  2. Native perennial grasses show evolutionary response to Bromus tectorum (Cheatgrass) invasion

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Invasive species can change selective pressures on native species by altering biotic and abiotic conditions in invaded habitats. Although invasions can lead to native species extirpation, they may also induce rapid evolutionary changes in remnant native plants. We investigated whether adult plants o...

  3. Mapping and spatial-temporal modeling of Bromus tectorum invasion in central Utah

    NASA Astrophysics Data System (ADS)

    Jin, Zhenyu

    Cheatgrass, or Downy Brome, is an exotic winter annual weed native to the Mediterranean region. Since its introduction to the U.S., it has become a significant weed and aggressive invader of sagebrush, pinion-juniper, and other shrub communities, where it can completely out-compete native grasses and shrubs. In this research, remotely sensed data combined with field collected data are used to investigate the distribution of the cheatgrass in Central Utah, to characterize the trend of the NDVI time-series of cheatgrass, and to construct a spatially explicit population-based model to simulate the spatial-temporal dynamics of the cheatgrass. This research proposes a method for mapping the canopy closure of invasive species using remotely sensed data acquired at different dates. Different invasive species have their own distinguished phenologies and the satellite images in different dates could be used to capture the phenology. The results of cheatgrass abundance prediction have a good fit with the field data for both linear regression and regression tree models, although the regression tree model has better performance than the linear regression model. To characterize the trend of NDVI time-series of cheatgrass, a novel smoothing algorithm named RMMEH is presented in this research to overcome some drawbacks of many other algorithms. By comparing the performance of RMMEH in smoothing a 16-day composite of the MODIS NDVI time-series with that of two other methods, which are the 4253EH, twice and the MVI, we have found that RMMEH not only keeps the original valid NDVI points, but also effectively removes the spurious spikes. The reconstructed NDVI time-series of different land covers are of higher quality and have smoother temporal trend. To simulate the spatial-temporal dynamics of cheatgrass, a spatially explicit population-based model is built applying remotely sensed data. The comparison between the model output and the ground truth of cheatgrass closure demonstrates

  4. Comparative effects of glyphosate and atrazine in chloroplast ultrastructure of wheat and downy brome. [Triticum aestivum; Bromus tectorum

    SciTech Connect

    Auge, R.M.; Gealy, D.R.; Ogg, A.G.; Franceschi, V.R.

    1987-04-01

    Developing and mature leaves of winter wheat (Triticum aestivum L. var. Daws) and the weed species downy brome (Bromus tectorum L.) were subjected to 10 mM (foliar application) and 1 mM (root application) herbicide solutions. Glyphosate (N-(phosphonomethyl) glycine) and atrazine (2-chloro-4-(ethyl-amino)-6-(isopropylamino)-s-triazine) were prepared in a carrier composed of 5% soybean oil concentrate, 35% acetone and 60% water. Penetration experiments with /sup 3/H-labelled herbicides assessed what percentage of herbicide entered leaves, and microautoradiography was used to determine qualitatively how much herbicide was present in the sections viewed with TEM. Tissue was excised at 4, 18, 62 and 200 hours, and then either freeze-substituted or fixed chemically. Ultrastructural effects of each herbicide on chloroplasts from leaves of newly-germinated seedlings and of well-tillered plants are depicted and discussed. Temporal differences in response of chloroplasts to each herbicide are noted.

  5. Direct effects of soil amendments on field emergence and growth of the invasive annual grass Bromus tectorum L. and the native perennial grass Hilaria jamesii (Torr.) Benth

    USGS Publications Warehouse

    Newingham, B.A.; Belnap, J.

    2006-01-01

    Bromus tectorum L. is a non-native, annual grass that has invaded western North America. In SE Utah, B. tectorum generally occurs in grasslands dominated by the native perennial grass, Hilaria jamesii (Torr.) Benth. and rarely where the natives Stipa hymenoides Roem. and Schult. and S. comata Trin. & Rupr. are dominant. This patchy invasion is likely due to differences in soil chemistry. Previous laboratory experiments investigated using soil amendments that would allow B. tectorum to germinate but would reduce B. tectorum emergence without affecting H. jamesii. For this study we selected the most successful treatments (CaCl2, MgCl2, NaCl and zeolite) from a previous laboratory study and applied them in the field in two different years at B. tectorum-dominated field sites. All amendments except the lowest level of CaCl2 and zeolite negatively affected B. tectorum emergence and/or biomass. No amendments negatively affected the biomass of H. jamesii but NaCl reduced emergence. Amendment effectiveness depended on year of application and the length of time since application. The medium concentration of zeolite had the strongest negative effect on B. tectorum with little effect on H. jamesii. We conducted a laboratory experiment to determine why zeolite was effective and found it released large amounts of Na+, adsorbed Ca2+, and increased Zn2+, Fe2+, Mn2+, Cu2+, exchangeable Mg2+, exchangeable K, and NH 4+ in the soil. Our results suggest several possible amendments to control B. tectorum. However, variability in effectiveness due to abiotic factors such as precipitation and soil type must be accounted for when establishing management plans. ?? Springer 2006.

  6. Effects of growth regulator herbicide on downy brome (Bromus tectorum) seed production

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Previous research showed growth regulator herbicides, such as picloram and aminopyralid, have a sterilizing effect on Japanese brome (Bromus japonicus Thunb.) that can reduce this invasive annual grass’s seed production nearly 100%. This suggests growth regulators might be used to control invasive ...

  7. Effects of Bromus tectorum invasion on microbial carbon and nitrogen cycling in two adjacent undisturbed arid grassland communities

    USGS Publications Warehouse

    Schaeffer, Sean M.; Ziegler, Susan E.; Belnap, Jayne; Evans, R.D.

    2012-01-01

    Soil nitrogen (N) is an important component in maintaining ecosystem stability, and the introduction of non-native plants can alter N cycling by changing litter quality and quantity, nutrient uptake patterns, and soil food webs. Our goal was to determine the effects of Bromus tectorum (C3) invasion on soil microbial N cycling in adjacent non-invaded and invaded C3 and C4 native arid grasslands. We monitored resin-extractable N, plant and soil δ13C and δ15N, gross rates of inorganic N mineralization and consumption, and the quantity and isotopic composition of microbial phospholipid biomarkers. In invaded C3 communities, labile soil organic N and gross and net rates of soil N transformations increased, indicating an increase in overall microbial N cycling. In invaded C4 communities labile soil N stayed constant, but gross N flux rates increased. The δ13C of phospholipid biomarkers in invaded C4 communities showed that some portion of the soil bacterial population preferentially decomposed invader C3-derived litter over that from the native C4 species. Invasion in C4 grasslands also significantly decreased the proportion of fungal to bacterial phospholipid biomarkers. Different processes are occurring in response to B. tectorum invasion in each of these two native grasslands that: 1) alter the size of soil N pools, and/or 2) the activity of the microbial community. Both processes provide mechanisms for altering long-term N dynamics in these ecosystems and highlight how multiple mechanisms can lead to similar effects on ecosystem function, which may be important for the construction of future biogeochemical process models.

  8. Mapping and monitoring cheatgrass dieoff in rangelands of the Northern Great Basin, USA

    USGS Publications Warehouse

    Boyte, Stephen P.; Wylie, Bruce K.; Major, Donald J.

    2015-01-01

    Understanding cheatgrass (Bromus tectorum) dynamics in the Northern Great Basin rangelands, USA, is necessary to effectively manage the region’s lands. This study’s goal was to map and monitor cheatgrass performance to identify where and when cheatgrass dieoff occurred in the Northern Great Basin and to discover how this phenomenon was affected by climatic, topographic, and edaphic variables. We also examined how fire affected cheatgrass performance. Land managers and scientists are concerned by cheatgrass dieoff because it can increase land degradation, and its causes and effects are not fully known. To better understand the scope of cheatgrass dieoff, we developed multiple ecological models that integrated remote sensing data with geophysical and biophysical data. The models’ R2 ranged from 0.71 to 0.88, and their root mean squared errors (RMSEs) ranged from 3.07 to 6.95. Validation of dieoff data showed that 41% of pixels within independently developed dieoff polygons were accurately classified as dieoff, whereas 2% of pixels outside of dieoff polygons were classified as dieoff. Site potential, a long-term spatial average of cheatgrass cover, dominated the development of the cheatgrass performance model. Fire negatively affected cheatgrass performance 1 year postfire, but by the second year postfire performance exceeded prefire levels. The landscape-scale monitoring study presented in this paper helps increase knowledge about recent rangeland dynamics, including where cheatgrass dieoffs occurred and how cheatgrass responded to fire. This knowledge can help direct further investigation and/or guide land management activities that can capitalize on, or mitigate the effects of, cheatgrass dieoff.

  9. Effect of repeated burning on plant and soil carbon and nitrogen in cheatgrass (Bromus tectorum) dominated ecosystems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background and Aims Fire has profound effects on ecosystem properties, but few studies have addressed the effect of repeated burns on soil nutrients, and none have been conducted in cold desert ecosystems where invasion by exotic annual grasses is resulting in greater fire frequency. In a 5 year stu...

  10. Cheatgrass percent cover change: Comparing recent estimates to climate change − Driven predictions in the Northern Great Basin

    USGS Publications Warehouse

    Boyte, Stephen P.; Wylie, Bruce K.; Major, Donald J.

    2016-01-01

    Cheatgrass (Bromus tectorum L.) is a highly invasive species in the Northern Great Basin that helps decrease fire return intervals. Fire fragments the shrub steppe and reduces its capacity to provide forage for livestock and wildlife and habitat critical to sagebrush obligates. Of particular interest is the greater sage grouse (Centrocercus urophasianus), an obligate whose populations have declined so severely due, in part, to increases in cheatgrass and fires that it was considered for inclusion as an endangered species. Remote sensing technologies and satellite archives help scientists monitor terrestrial vegetation globally, including cheatgrass in the Northern Great Basin. Along with geospatial analysis and advanced spatial modeling, these data and technologies can identify areas susceptible to increased cheatgrass cover and compare these with greater sage grouse priority areas for conservation (PAC). Future climate models forecast a warmer and wetter climate for the Northern Great Basin, which likely will force changing cheatgrass dynamics. Therefore, we examine potential climate-caused changes to cheatgrass. Our results indicate that future cheatgrass percent cover will remain stable over more than 80% of the study area when compared with recent estimates, and higher overall cheatgrass cover will occur with slightly more spatial variability. The land area projected to increase or decrease in cheatgrass cover equals 18% and 1%, respectively, making an increase in fire disturbances in greater sage grouse habitat likely. Relative susceptibility measures, created by integrating cheatgrass percent cover and temporal standard deviation datasets, show that potential increases in future cheatgrass cover match future projections. This discovery indicates that some greater sage grouse PACs for conservation could be at heightened risk of fire disturbance. Multiple factors will affect future cheatgrass cover including changes in precipitation timing and totals and

  11. Impact of prescribed fire and other factors on cheatgrass persistence in a Sierra Nevada ponderosa pine forest

    USGS Publications Warehouse

    Keeley, J.E.; McGinnis, T.W.

    2007-01-01

    Following the reintroduction of fire Bromus tectorum has invaded the low elevation ponderosa pine forests in parts of Kings Canyon National Park, California. We used prescribed burns, other field manipulations, germination studies, and structural equation modelling, to investigate how fire and other factors affect the persistence of cheatgrass in these forests. Our studies show that altering burning season to coincide with seed maturation is not likely to control cheatgrass because sparse fuel loads generate low fire intensity. Increasing time between prescribed fires may inhibit cheatgrass by increasing surface fuels (both herbaceous and litter), which directly inhibit cheatgrass establishment, and by creating higher intensity fires capable of killing a much greater fraction of the seed bank. Using structural equation modelling, postfire cheatgrass dominance was shown to be most strongly controlled by the prefire cheatgrass seedbank; other factors include soil moisture, fire intensity, soil N, and duration of direct sunlight. Current fire management goals in western conifer forests are focused on restoring historical fire regimes; however, these frequent fire regimes may enhance alien plant invasion in some forest types. Where feasible, fire managers should consider the option of an appropriate compromise between reducing serious fire hazards and exacerbating alien plant invasions. ?? IAWF 2007.

  12. Cheatgrass and Grazing Rangelands

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Charles Elliot Fleming was one of the first scientists to work on the western range. In 1946 he published a series of questions concerning grazing of the exotic annual cheatgrass (Bromus tectorm), which had invaded millions of acres of the western rangelands. The introduction and subsequent invasi...

  13. Crested wheatgrass-cheatgrass seedling competition in a mixed-density design

    USGS Publications Warehouse

    Francis, Mark G.; Pyke, David A.

    1996-01-01

    Plant competition experiments have historically used designs that are difficult to interpret due to confounding problems. Recently, designs based on a 'response function' approach have been proposed and tested in various plant mixture settings. For this study, 3 species were used that are important in current revegetation practices in the Intermountain West. 'Nordan' (Agropyron desertorum [Fish. ex Link] Shult.) and 'Hycrest' (A. cristatum [L.] Gaertn. x desertorum) crested wheatgrass are commonly-used revegetation species on rangelands susceptible to cheatgrass (Bromus tectorum L.) invasion, although little quantitative data exist that compare their competitive abilities. We evaluated the competitive ability of Hycrest and Nordan seedlings in 2-species mixtures with cheatgrass in a greenhouse study. Linear and nonlinear models were developed for a range of densities (130- 520 seeds m-2) for each species to predict median above-ground biomass and tiller numbers and to further test the usefulness of this design for evaluating species to rehabilitate rangelands. In both experiments, increasing Hycrest and Nordan densities reduced their own biomass and tiller production while increasing Hycrest densities reduced cheatgrass biomass and tiller production. Nordan did not affect cheatgrass biomass and tiller production. However, increasing cheatgrass densities reduced Hycrest and Nordan biomass and tiller production, and its own biomass and tiller production. The competition index i.e. substitution rate, indicated that Hycrest seedlings were better competitors with cheatgrass than Nordan, although in all mixtures, cheatgrass plants were the superior competitors. Further field research using this design, where environmental inputs are less optimal and diverse, is needed to validate these results and to further evaluate the use of this approach in examining effects of intra- and interspecific competition.

  14. Despite spillover, a shared pathogen promotes native plant persistence in a cheatgrass-invaded grassland.

    PubMed

    Mordecai, Erin A

    2013-12-01

    How pathogen spillover influences host community diversity and composition is poorly understood. Spillover occurs when transmission from a reservoir host species drives infection in another host species. In cheatgrass-invaded grasslands in the western United States, a fungal seed pathogen, black fingers of death (Pyrenophora semeniperda), spills over from exotic cheatgrass (Bromus tectorum) to native perennial bunchgrasses such as squirreltail (Elymus elymoides). Previous theoretical work based on this system predicts that pathogens that spill over can favor either host coexistence, the exclusion of either host species, or priority effects, depending on species-specific transmission rates and pathogen tolerance. Here, these model predictions were tested by parameterizing a population growth model with field data from Skull Valley, Utah, USA. The model suggests that, across the observed range of demographic variation, the pathogen is most likely to provide a net benefit to squirreltail and a net cost to cheatgrass, though both effects are relatively weak. Although cheatgrass (the reservoir host) is more tolerant, squirreltail is far less susceptible to infection, and its long-lived adult stage buffers population growth against seed losses to the pathogen. This work shows that, despite pathogen spillover, the shared pathogen promotes native grass persistence by reducing exotic grass competition. Counterintuitively, the reservoir host does not necessarily benefit from the presence of the pathogen, and may even suffer greater costs than the nonreservoir host. Understanding the consequences of shared pathogens for host communities requires weighing species differences in susceptibility, transmission, and tolerance using quantitative models. PMID:24597221

  15. Biotic soil crusts in relation to topography, cheatgrass, and fire in the Columbia Basin, Washington

    USGS Publications Warehouse

    Ponzetti, Jeanne; McCune, B.; Pyke, David A.

    2007-01-01

    We studied lichen and bryophyte soil crust communities in a large public grazing allotment within a sagebrush steppe ecosystem in which the biotic soil crusts are largely intact. The allotment had been rested from grazing for 12 years, but experienced an extensive series of wildfires. In the 350, 4 ?? 0.5 m plots, stratified by topographic position, we found 60 species or species groups that can be distinguished in the field with a hand lens, averaging 11.5 species groups per plot. Lichen and bryophyte soil crust communities differed among topographic positions. Draws were the most disturbed, apparently from water erosion in a narrow channel and mass wasting from the steepened sides. Presumably because of this disturbance, draws had the lowest average species richness of all the topographic strata we examined. Biotic crust species richness and cover were inversely related to cover of the invasive annual, cheatgrass (Bromus tectorum), and positively related to cover of native bunchgrasses. Integrity of the biotic crust was more strongly related to cheatgrass than to fire. In general, we observed good recovery of crusts following fire, but only in those areas dominated by perennial bunchgrasses. We interpret the resilience of the biotic crust, in this case, to the low abundance of cheatgrass, low amounts of soil disturbance and high moss cover. These fires have not resulted in an explosion of the cheatgrass population, perhaps because of the historically low levels of livestock grazing.

  16. Cheatgrass is favored by warming but not CO2 enrichment in a semi-arid grassland.

    PubMed

    Blumenthal, Dana M; Kray, Julie A; Ortmans, William; Ziska, Lewis H; Pendall, Elise

    2016-09-01

    Elevated CO2 and warming may alter terrestrial ecosystems by promoting invasive plants with strong community and ecosystem impacts. Invasive plant responses to elevated CO2 and warming are difficult to predict, however, because of the many mechanisms involved, including modification of phenology, physiology, and cycling of nitrogen and water. Understanding the relative and interactive importance of these processes requires multifactor experiments under realistic field conditions. Here, we test how free-air CO2 enrichment (to 600 ppmv) and infrared warming (+1.5 °C day/3 °C night) influence a functionally and phenologically distinct invasive plant in semi-arid mixed-grass prairie. Bromus tectorum (cheatgrass), a fast-growing Eurasian winter annual grass, increases fire frequency and reduces biological diversity across millions of hectares in western North America. Across 2 years, we found that warming more than tripled B. tectorum biomass and seed production, due to a combination of increased recruitment and increased growth. These results were observed with and without competition from native species, under wet and dry conditions (corresponding with tenfold differences in B. tectorum biomass), and despite the fact that warming reduced soil water. In contrast, elevated CO2 had little effect on B. tectorum invasion or soil water, while reducing soil and plant nitrogen (N). We conclude that (1) warming may expand B. tectorum's phenological niche, allowing it to more successfully colonize the extensive, invasion-resistant northern mixed-grass prairie, and (2) in ecosystems where elevated CO2 decreases N availability, CO2 may have limited effects on B. tectorum and other nitrophilic invasive species. PMID:27090757

  17. Competitive seedlings and inherited traits: a test of rapid evolution of Elymus multisetus (big squirreltail) in response to cheatgrass invasion

    PubMed Central

    Rowe, Courtney L J; Leger, Elizabeth A

    2011-01-01

    Widespread invasion by Bromus tectorum (cheatgrass) in the Intermountain West has drastically altered native plant communities. We investigated whether Elymus multisetus (big squirreltail) is evolving in response to invasion and what traits contribute to increased performance. Seedlings from invaded areas exhibited significantly greater tolerance to B. tectorum competition and a greater ability to suppress B. tectorum biomass than seedlings from adjacent uninvaded areas. To identify potentially adaptive traits, we examined which phenological and phenotypic traits were correlated with seedling performance within the uninvaded area, determined their genetic variation by measuring sibling resemblance, and asked whether trait distribution had shifted in invaded areas. Increased tolerance to competition was correlated with early seedling root to shoot ratio, root fork number, and fine root length. Root forks differed among families, but none of these traits differed significantly across invasion status. Additionally, we surveyed more broadly for traits that varied between invaded and uninvaded areas. Elymus multisetus plants collected from invaded areas were smaller, allocated more biomass to roots, and produced a higher percentage of fine roots than plants from uninvaded areas. The ability of native populations to evolve in response to invasion has significant implications for the management and restoration of B. tectorum-invaded communities. PMID:25567997

  18. Assessing resilience and state-transition models with historical records of cheatgrass Bromus tectorum invasion in North American sagebrush-steppe

    Technology Transfer Automated Retrieval System (TEKTRAN)

    1. Resilience-based approaches are increasingly being called upon to inform ecosystem management, particularly in arid and semi-arid regions. This requires management frameworks that can assess ecosystem dynamics, both within and between alternative states, at relevant time scales. 2. We analysed l...

  19. Soil Seed Bank Responses to Postfire Herbicide and Native Seeding Treatments Designed to Control Bromus tectorum in a Pinyon–Juniper Woodland at Zion National Park, USA

    USGS Publications Warehouse

    Brooks, Matthew L.; Hondo Brisbin, graduate student; Andrea Thode, Associate Professor; Karen Weber, graduate student

    2013-01-01

    The continued threat of an invasive, annual brome (Bromus) species in the western United States has created the need for integrated approaches to postfire restoration. Additionally, the high germination rate, high seed production, and seed bank carryover of annual bromes points to the need to assay soil seed banks as part of monitoring programs. We sampled the soil seed bank to help assess the effectiveness of treatments utilizing the herbicide Plateau® (imazapic) and a perennial native seed mix to control annual Bromus species and enhance perennial native plant establishment following a wildfire in Zion National Park, Utah. This study is one of few that have monitored the effects of imazapic and native seeding on a soil seed bank community and the only one that we know of that has done so in a pinyon–juniper woodland. The study made use of untreated, replicated controls, which is not common for seed bank studies. One year posttreatment, Bromus was significantly reduced in plots sprayed with herbicide. By the second year posttreatment, the effects of imazapic were less evident and convergence with the controls was evident. Emergence of seeded species was low for the duration of the study. Dry conditions and possible interactions with imazapic probably contributed to the lack of emergence of seeded native species. The perennial grass sand dropseed outperformed the other species included in the seed mix. We also examined how the treatments affected the soil seed bank community as a whole. We found evidence that the herbicide was reducing several native annual forbs and one nonnative annual forb. However, overall effects on the community were not significant. The results of our study were similar to what others have found in that imazapic is effective in providing a short-term reduction in Bromus density, although it can impact emergence of nontarget species.

  20. Stress-gradient hypothesis explains susceptibility to Bromus tectorum invasion and community stability in North America's semi-arid Artemisia tridentata wyomingensis ecosystems

    USGS Publications Warehouse

    Reisner, Michael D.; Doescher, Paul S.; Pyke, David A.

    2015-01-01

    Results/Conclusions: Cattle herbivory, a novel disturbance and selective force, was a significant component of two overlapping stress gradients most strongly associated with observed shifts in interactions. Facilitation and competition were strongest and most frequent at the highest and lowest stress levels along both gradients, respectively. Contrasting ecological optima among native and non-native beneficiaries led to strikingly different patterns of interactions. The four native bunchgrasses with the strongest competitive response abilities exhibited the strongest facilitation at their upper limits of stress tolerance, while the two non-natives exhibited the strongest competition at the highest stress levels, which coincided with their maximum abundance. Artemisia facilitation enhanced stability at intermediate stress levels by providing a refuge for native bunchgrasses, which in turn reduced the magnitude of B. tectorum invasion. However, facilitation was a destabilizing force at the highest stress levels when native bunchgrasses became obligate beneficiaries dependent on facilitation for their persistence. B. tectorum dominated these communities, and the next fire may convert them to annual grasslands.

  1. Nitrogen limitation, 15N tracer retention, and growth response in intact and Bromus tectorum-invaded Artemisia tridentata ssp. wyomingensis communities

    USGS Publications Warehouse

    Witwicki, Dana L.; Doescher, Paul S.; Pyke, David A.; DeCrappeo, Nicole M.; Perakis, Steven S.

    2012-01-01

    Annual grass invasion into shrub-dominated ecosystems is associated with changes in nutrient cycling that may alter nitrogen (N) limitation and retention. Carbon (C) applications that reduce plant-available N have been suggested to give native perennial vegetation a competitive advantage over exotic annual grasses, but plant community and N retention responses to C addition remain poorly understood in these ecosystems. The main objectives of this study were to (1) evaluate the degree of N limitation of plant biomass in intact versus B. tectorum-invaded sagebrush communities, (2) determine if plant N limitation patterns are reflected in the strength of tracer 15N retention over two growing seasons, and (3) assess if the strength of plant N limitation predicts the efficacy of carbon additions intended to reduce soil N availability and plant growth. Labile C additions reduced biomass of exotic annual species; however, growth of native A. tridentata shrubs also declined. Exotic annual and native perennial plant communities had divergent responses to added N, with B. tectorum displaying greater ability to use added N to rapidly increase aboveground biomass, and native perennials increasing their tissue N concentration but showing little growth response. Few differences in N pools between the annual and native communities were detected. In contrast to expectations, however, more 15N was retained over two growing seasons in the invaded annual grass than in the native shrub community. Our data suggest that N cycling in converted exotic annual grasslands of the northern Intermountain West, USA, may retain N more strongly than previously thought.

  2. Root interaction between Bromud tectorum and Poa pratensis: a three-dimensional analysis

    SciTech Connect

    Bookman, P.A.; Mack, R.N.

    1982-06-01

    The spatial distribution of roots of two alien grasses, Bromus tectorum and Poa pratensis, grown singly and in a mixture, was examined using a double-labelling radioisotope technique. Interactions between the root systems of these plants led to a restricted B. tectorum rooting volume in P. pratensis neighborhoods greater than or equal to30-d-old. The roots of B. tectorum failed to develop laterally. The altered B. tectorum root systems may contribute to its inability to persist in established P. pratensis swards.

  3. Using Current and Historic Climate Data and Bayesian Belief Networks to Predict Optimum Satellite Image Acquisition Periods for Detecting Cheatgrass on the Snake River Plain, Idaho

    NASA Astrophysics Data System (ADS)

    Rope, R. C.; Ames, D. P.; Jerry, T. D.; Cherry, S. J.

    2005-12-01

    Invasive plant species, such as Bromus tectorum (cheatgrass), cost the United States over $36 billion per year and have encroached upon over 100 million acres while impacting range site productivity, disturbing wildlife habitat, altering the wildland fire regime and frequencies, and reducing biodiversity. Because of these adverse impacts, federal, tribal, state, and county land managers are faced with the challenge of prevention, early detection, management, and monitoring of invasive plants. Often these managers rely on the analysis of remotely sensed imagery as part of their management plan. However, it's difficult to predict specific phenological events that allow for the spectral discrimination of invasive species using only remotely sensed imagery. To address this issue tools are being developed to model and view optimal periods to collect high spatial and/or spectral resolution remotely sensed data for refined detection and mapping of invasive species and for use as a decision support tool for land managers. These tools involve the integration of historic and current climate data (cumulative growing days and precipitation) satellite imagery (MODIS) and Bayesian Belief Networks, and a web ArcIMS application to distribute the information. The general approach is to issue an initial forecast early in the year based on the previous years' data. As the year progresses, air temperature, precipitation and newly acquired low resolution MODIS satellite imagery will be used to update the prediction. Updating will be accomplished using a Bayesian Belief Network model that indicates the probabilistic relationships between prior years' conditions and those of the current year. These tools have specific application in providing a means for which land managers can efficiently and effectively detect, map, and monitor invasive plant species, specifically cheatgrass, in western rangelands. This information can then be integrated into management studies and plans to help land

  4. Herbicide efficacy and perennial grass establishment

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cheatgrass (Bromus tectorum) invasion has astronomically altered native plant communities throughout the Intermountain West. Cheatgrass truncates secondary succession by outcompeting native plant species for limited resources, thus building persistent seed banks to take advantage of conditions that...

  5. Rehabilitation of degraded rangelands: lessons learned

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The introduction and subsequent invasion of cheatgrass (Bromus tectorum) has had astronomical effects to Great Basin rangelands. Cheatgrass has truncated secondary succession by outcompeting native plant species for limited resources, thus building persistent seed banks that take advantage of condi...

  6. Germination Characteristics Of Some Great Basin Native Annual Forb Species

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Great Basin native plant communities are being replaced by the annual invasive cheatgrass (Bromus tectorum). Cheatgrass exhibits a germination syndrome that is characteristic of facultative winter annuals. Although perennials dominate these communities, native annuals are present in many sites. Germ...

  7. Ecosystem impacts of exotic annual invaders in the Genus Bromus

    USGS Publications Warehouse

    Germino, Matthew J.; Belnap, Jayne; Stark, John M.; Allen, Edith B.; Rau, Benjamin M.

    2016-01-01

    An understanding of the impacts of exotic plant species on ecosystems is necessary to justify and guide efforts to limit their spread, restore natives, and plan for conservation. Invasive annual grasses such as Bromus tectorum, B. rubens, B. hordeaceus, and B. diandrus (hereafter collectively referred to as Bromus) transform the structure and function of ecosystems they dominate. Experiments that prove cause-and-effect impacts of Bromus are rare, yet inferences can be gleaned from the combination of Bromus-ecosystem associations, ecosystem condition before/after invasion, and an understanding of underlying mechanisms. Bromus typically establishes in bare soil patches and can eventually replace perennials such as woody species or bunchgrasses, creating a homogeneous annual cover. Plant productivity and cover are less stable across seasons and years when Bromus dominates, due to a greater response to annual climate variability. Bromus’ “flash” of growth followed by senescence early in the growing season, combined with shallow rooting and annual habit, may lead to incomplete use of deep soil water, reduced C sequestration, and accelerated nutrient cycling. Litter produced by Bromus alters nearly all aspects of ecosystems and notably increases wildfire occurrence. Where Bromus has become dominant, it can decrease soil stability by rendering soils bare for months following fire or episodic, pathogen-induced stand failure. Bromus-invaded communities have lower species diversity, and associated species tend to be generalists adapted to unstable and variable habitats. Changes in litter, fire, and soil properties appear to feedback to reinforce Bromus’ dominance in a pattern that portends desertification.

  8. Studies on the reproductive biology of downy brome (Bromus tectorum)

    SciTech Connect

    Richardson, J.M.

    1986-01-01

    The ability of downy brome to successfully infest crop lands is partially due to its prolific nature. To better understand its reproductive biology, studies investigating (1) effects of temperature and photoperiod on flowering, (2) prevention of downy brome seed information with herbicides, and (3) effects of drought on reproduction, were conducted. Seedling vernalization was more effective than seed vernalization in promoting downy brome flowering. Vernalizing imbibed downy brome caryopses at 3 C for 0 to 30 days did not induce rapid flowering. Downy brome seedlings were exposed to six photoperiod/temperature treatments. After transfer to long days, plants from the short da/3 C treatment flowered within 30 days. DPX-Y6202 and fluazifop-butyl were tested for their ability to prevent seed formation in downy brome. Fluazifop-butyl prevented seed formation over a wider range of application rates and growth stages than did DPX-Y6202. Seed production was prevented most readily by herbicide applications made early in the reproductive cycle. Translocation of radiolabel was greater with /sup 14/C-fluazifop-butyl than with /sup 14/C-DPX-Y6202, particularly into developing spikelets. Microautoradiographic techniques were used to identify mechanisms involved in the prevention of downy brome seed formation by these herbicides. Tissue localization of both herbicides was similar. The highest concentration of radiolabel was found in developing pollen grains, suggesting that the herbicides prevented seed formation by interrupting pollen development or function. Water stress reduced apparent photosynthesis and increased diffusive resistance of flag leaves.

  9. Germination prediction from soil moisture and temperature data across the Great Basin

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Preventing cheatgrass (Bromus tectorum) dominance associated with frequent wildfires depends, in part, on successful establishment of desirable species sown in fire rehabilitation and fuel control projects. We tested the effects of fire, herbicide applications, and mechanical treatments on predicte...

  10. Big sagebrush transplanting success in crested wheatgrass stands

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The conversion of formerly big sagebrush (Artemisia tridentate ssp. wyomingensis)/bunchgrass communities to annual grass dominance, primarily cheatgrass (Bromus tectorum), in Wyoming big sagebrush ecosystems has sparked the increasing demand to establish big sagebrush on disturbed rangelands. The e...

  11. Germination prediction from soil moisture and temperature in the Great Basin

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Preventing cheatgrass (Bromus tectorum L.) dominance associated with frequent wildfires may depend on successful establishment of desirable species sown in rehabilitation and fuel control projects. Ranking potential species success to develop more performance-based species selection for revegetatio...

  12. Nitrogen uptake by perennial and invasive annual grass seedlings: Nitrogen form effects

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Infestation by exotic annual cheatgrass (Bromus tectorum L.) and medusahead wildrye (Taeniatherum caput-medusae ssp. asperum [Simk.] Meldris) have decreased productivity and biological diversity and increased the frequency of rangeland wildfire in the Intermountain West. On disturbed sites, squirrel...

  13. Postfire seeding and plant community recovery in the Great Basin

    Technology Transfer Automated Retrieval System (TEKTRAN)

    As wildland fire frequency increases around the globe, increased understanding of plant community recovery in burned landscapes is needed to improve effectiveness of rehabilitation efforts. We measured establishment of seeded species, colonization of Bromus tectorum L. (cheatgrass), and recovery of ...

  14. Cheatgrass Dead Zones in Northern Nevada

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Reports of areas of cheatgrass die-off are becoming more frequent. In 2009, we investigated cheatgrass die-off in north-central Nevada. Dead zones ranged from several to hundreds of acres in size and were largely unvegetated and covered by cheatgrass litter with a distinct gray cast. We collected re...

  15. Hard traits of three Bromus species in their source area explain their current invasive success

    NASA Astrophysics Data System (ADS)

    Fenesi, Annamária; Rédei, Tamás; Botta-Dukát, Zoltán

    2011-09-01

    We address two highly essential question using three Eurasian Bromus species with different invasion success in North America as model organisms: (1) why some species become invasive and others do not, and (2) which traits can confer pre-adaptation for species to become invasive elsewhere. While the morphology and phenology of the chosen bromes ( Bromus tectorum, Bromus sterilis and Bromus squarrosus) are highly similar, we measured complex traits often associated with invasive success: phenotypic plasticity, competitive ability and generalist-specialist character. We performed common-garden experiments, community- and landscape-level surveys in areas of co-occurrence in Central Europe (Hungary) that could have served as donor region for American introductions. According to our results, the three bromes are unequally equipped with trait that could enhance invasiveness. B. tectorum possesses several traits that may be especially relevant: it has uniquely high phenotypic plasticity, as demonstrated in a nitrogen addition experiment, and it is a habitat generalist, thriving in a wide range of habitats, from semi-natural to degraded ones, and having the widest co-occurrence based niche-breadth. The strength of B. sterilis lies in its ability to use resources unexploited by other species. It can become dominant, but only in one non-natural habitat type, namely the understorey of the highly allelopathic stands of the invasive Robinia pseudoacacia. B. squarrosus is a habitat specialist with low competitive ability, always occurring with low coverage. This ranking of the species' abilities can explain the current spreading success of the three bromes on the North American continent, and highlight the high potential of prehistoric invaders (European archaeophytes) to become invasive elsewhere.

  16. Perennial grass dominance: creating a resilient plant community in an exotic annual grass invaded rangeland

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Millions of hectares of western rangelands have been invaded by the exotic and invasive annual grass, cheatgrass (Bromus tectorum). Cheatgrass provides a fine-textured, early maturing fuel that has increased the chance, rate, spread and season of wildfire to public and private lands throughout the ...

  17. Increased Seedling Vigor in 'Hycrest II' Crested Wheatgrass

    Technology Transfer Automated Retrieval System (TEKTRAN)

    "Hycrest II' crested wheatgrass (Agropyron cristatum L.) (Reg. No. CV-__, PI______). It has been estimated that cheatgrass (Bromus tectorum L.) has displaced around 10 million ha of perennial vegetation within the Great Basin. The control of cheatgrass without replacement by desirable perennial sp...

  18. Evaluating perennial grass competition as a management tool

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Evaluation of plant competition is highly dependent on life stage and cycle. One of the largest problems that Great Basin rangelands face is the competitive nature of the exotic and invasive annual grass, cheatgrass (Bromus tectorum). Advantages of cheatgrass are often attributed to large seed produ...

  19. Assessment of horse creek conservation seeding

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Millions of acres of big sagebrush (Artemisia tridentata)/bunchgrass communities have been invaded by the exotic and invasive annual, cheatgrass (Bromus tectorum) and require pro-active management to reduce the risk of catastrophic wildfires. The introduction of cheatgrass has increased the chance, ...

  20. Downy Brome: evidence for soil engineering

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bromus tectorum L. (downy brome, cheatgrass) is an invasive Eurasian grass largely responsible for landscape level conversion of sagebrush/bunchgrass communities to annual grass dominance. We tested the hypothesis that B. tectorum alters or “engineers” the soil to favor its growth. The hypothesis wa...

  1. Post-fire Downy Brome (Bromus tectorum) invasion at high elevation in Wyoming

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The invasive annual grass downy brome is the most ubiquitous weed in sagebrush systems of western North America. The center of invasion has largely been the Great Basin region, but there is an increasing abundance and distribution in the Rocky Mountain States. We evaluated post-fire vegetation chang...

  2. Transition from sagebrush steppe to annual grass (Bromus tectorum): influence on belowground carbon and nitrogen

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Vegetation changes associated with climate shifts and anthropogenic disturbance have major impacts on biogeochemical cycling. Much of the interior western United States currently is dominated by sagebrush (Artemisia tridentate Nutt.) ecosystems. At low to intermediate elevations, sagebrush ecosystem...

  3. Bromus tectorum and native grass establishment under drought and warming in sagebrush steppe after fire

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fire and climate change are two important drivers of desert plant communities. Changes in precipitation and temperature due to climate change will create novel environmental conditions that will likely affect post-fire plant establishment, invasions, and eventually alter plant community assemblages....

  4. Soil engineering facilitates Downy brome (Bromus tectorum L.) growth - A case study

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Some exotic plants are able to engineer new host soils and engender characteristics that potentially increase their growth. We hypothesized that this positive feedback may be a facet in the competitiveness of the exotic annual grass downy brome. Using rhizotrons in the greenhouse, we compared the gr...

  5. Effects of soil amendments on germination and emergence of downy brome (Bromus tectorum) and Hilaria jamesii

    USGS Publications Warehouse

    Belnap, J.; Sherrod, S.K.; Miller, M.E.

    2003-01-01

    Downy brome is an introduced Mediterranean annual grass that now dominates millions of hectares of western U.S. rangelands. The presence of this grass has eliminated many native species and accelerated wildfire cycles. The objective of this study was to identify soil additives that allowed germination but inhibited emergence of downy brome, while not affecting germination or emergence of the native perennial grass Hilaria jamesii. On the basis of data from previous studies, we focused on additives that altered the availability of soil nitrogen (N), phosphorus (P), and potassium (K). Most water-soluble treatments inhibited downy brome germination and emergence. We attribute the inhibitory effects of these treatments to excessive salinity and ion-specific effects of the additives themselves. An exception to this was oxalic acid, which showed no effect. Most water-insoluble treatments had no effect in soils with high P but did have an effect in soils with low P. Zeolite was effective regardless of P level, probably due to the high amounts of Na+ it added to the soil solution. Most treatments at higher concentrations resulted in lower downy brome emergence rates in soils currently dominated by downy brome than in uninvaded (but theoretically invadable) Hilaria soils. This difference is possibly attributable to inherent differences in labile soil P. In Stifa soils, where Stipa spp. grow, but which are generally considered to be uninvadable by downy brome, additions of high amounts of N resulted in lower emergence. This may have been an effect of NH4+ interference with uptake of K or other cations or toxicity of high N. We also saw a positive relationship between downy brome emergence and pH in Stipa soils. Hilaria development parameters were not as susceptible to the treatments, regardless of concentration, as downy brome. Our results suggest that there are additions that may be effective management tools for inhibiting downy brome in calcareous soils, including (1) high salt applications, (2) K-reducing additions (e.g., Mg), and (3) P-reducing additions.

  6. Variable Impacts of Imazapic on Downy Brome (Bromus Tectorum) and Seeded Species in Two Rangeland Communities

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In the Great Basin desert of North America, over 20 million acres of land have been invaded by downy brome. A common control measure includes herbicide use combined with seeding of desirable species. The herbicide imazapic is registerred for use on rangelands and provides effective short-term cont...

  7. Suppression of cheatgrass by established perennial grasses: I. mechanisms

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cheatgrass is often considered a competitive species. In a greenhouse experiment using rhizotrons, we tested the effect of established perennial grasses (Indian ricegrass, creeping wildrye, and Snake River wheatgrass) on the growth of cheatgrass. The soil was a sandy loam A horizon of a Xeric Haploc...

  8. Monitoring invasive species using 1-mm GSD geocoded aerial surveys: a cost effective means of getting details, locations, and sample numbers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Half a century ago Aldo Leopold observed, “It is impossible fully to protect cheat country from fire...,” and chided, “We tilt windmills in behalf of conservation in convention halls... but on the back forty we disclaim even owning a lance.” “Lances” effective against cheatgrass (Bromus tectorum L.)...

  9. Revegetation potential of Great Basin native annuals and perennial grasses: Does facilitation occur?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Revegetation of degraded Great Basin rangelands is a challenging task. In an already unforgiving environment the addition of exotic invasive annual weeds, such as cheatgrass (Bromus tectorum) have added to this challenge. Increasing interest in plant facilitation research has suggested using nati...

  10. Suppressing downy brome following wildfires

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Downy brome (Bromus tectorum), more widely known as cheatgrass, has invaded millions of hectares of rangelands throughout the Intermountain West. Downy brome provides an early maturing, fine-textured fuel that has increased the chance, rate, season and spread of wildfires. In July 2006, a wildfire b...

  11. Evaluation of regionally-collected sideoats grama and big galleta grass for wildfire revegetation in the Eastern Upper Mojave Desert

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Increased wildfires in the western U.S. are due to the cyclic accumulation and burning of invasive annual plants such as cheatgrass (Bromus tectorum) and red brome (B. rubens), which reduces native rangeland species and results in servere economic losses and land degradation. Fire was not prevalent...

  12. Supplemental description of Paraphelenchus acontioides Taylor and Pillai, (Tylenchida: Paraphelenchidae), with ribosomal DNA trees and a morphometric compendium of female Paraphelenchus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nematodes were isolated from surface-sterilized stems of cheatgrass, Bromus tectorum L. (Poaceae) in Colorado, grown on Fusarium (Hypocreaceae) fungus culture, and identified as Paraphelenchus acontioides Taylor and Pillai, 1967. Morphometrics and micrographic morphology of this species are given t...

  13. Weed-suppressive bacteria to reduce annual grass weeds

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cheatgrass (Bromus tectorum L.), medusahead (Taeniatherum caput-medusae [L.] Nevski) and jointed goatgrass (Aegilops cylindrica L.) are exotic, annual grasses that negatively affect cereal production in cropland; reduce protein-rich forage for cattle; choke out native plants in the shrub-steppe habi...

  14. Evaluation of regionally-collected sideoats grams and big galleta grass for wildfire revegetation in the Eastern Upper Mojave Desert

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Increased wildfires in the western U.S. are due to the cyclic accumulation and burning of invasive annual plants such as cheatgrass (Bromus tectorum) and red brome (B. rubens), which reduces native rangeland species and results in severe economic losses and land degradation. Fire was not prevalent ...

  15. Conservation seeding and diverse seed species performance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The rehabilitation of degraded big sagebrush (Artemisia spp.) communities infested with cheatgrass (Bromus tectorum) and other competitive weeds is a daunting task facing resource managers and land owners. In an effort to improve wildlife and livestock forage on degraded rangelands, the USDA-ARS-Gr...

  16. The effect of sucrose application on soil nutrient availability

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil nutrient availability is a principal factor constraining the invasiveness of exotic weeds such as cheatgrass (Bromus tectorum L.). The soil microbial community is generally C limited; thus, providing a labile C source can cause microbes to proliferate and immobilize soil nutrients, particularly...

  17. Wildlife Habitat Improvement Using Range Improvement Practices

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wildfires in the Intermountain West are and annual event. The introduction and subsequent invasion of cheatgrass (Bromus tectorum) onto millions of hectares of rangelands throughout the West has resulted in devastating wildfires. With each passing wildfire season more and more critical wildlife habi...

  18. Hydrologic and erosion responses to wildfire along the rangeland-xeric forest continuum in the western US: a review and model of hydrologic vulnerability

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The recent increased wildfire activity across the rangeland-xeric forest continuum in the western United States presents landscape-scale consequences relative to runoff and erosion. Concomitant cheatgrass (Bromus tectorum L.) invasions, plant community transitions, and a warming climate in recent de...

  19. EXPERIENCING THE SUCCESS AND FAILURES OF RANGELAND RESTORATION/REVEGETATION

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Anyone who has ever attempted to restore (native species) or revegetate (introduced species) disturbed arid rangelands knows the frustration inherent in such efforts. Exotic species such as cheatgrass (Bromus tectorum) and medusahead (Taeniatherum caput-medusae) significantly add to the complicatio...

  20. Breeding Strategies for the Development of Native Grasses

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Vast areas of semiarid rangelands in western USA are severely degraded and infested with troublesome weeds such as cheatgrass (Bromus tectorum L.) and medusahead rye (Taeniatherum asperum (Sim.) Nevski). Re-seeding with appropriate plant materials that are adapted to the site and competitive enough...

  1. The tri-soil experiment: do plants discriminate among vegetation soil types?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We tested if rooting mass and root nutrient uptake of cheatgrass (Bromus tectorum) or creeping wildrye (Leymus triticoides) were influenced by vegetation soil type. Three soil types (A horizons), similar in gross physical and chemical properties, were freshly-collected. The soils varied in the veget...

  2. The effects of precipitation and soil type on three invasive annual grasses in the western United States

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sagebrush-steppe ecosystems in the Great Basin are highly susceptible to annual grass invasion. Large regions are covered by Bromus tectorum (cheatgrass), but there has been a recent upsurge in the abundance and distribution of Taeniatherum caput-medusae (medusahead) and Ventenata dubia (ventenata)....

  3. Integrated management of downy brome in winter wheat

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Downy brome (Bromus tectorum L.), also known as cheatgrass, was introduced into North America from the Mediterranean area of Europe. It was first identified in the eastern United States in 1861, and by 1914 this invasive weed had spread throughout the continent. Downy brome is adapted to climates wi...

  4. Ecology, genetics, and biological control of invasive annual grasses in the Great Basin

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Several annual grass species native to Eurasia, including cheatgrass (Bromus tectorum), red brome (B. rubens), and medusahead (Taeniatherum caput-medusae) have become invasive in the western USA. These invasive species degrade rangelands by compromising forage, outcompeting native flora, and exacerb...

  5. The importance of persistent monitoring of great basin rangeland rehabilitation efforts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    It has long been acknowledged the drastic change in fire cycles of the Great Basin rangelands due to cheatgrass (Bromus tectorum) invasion (Billings 1952, Young and Evans 1974, Wright 1980). An annual grass fire cycle now exists with return intervals less than 5 years compared to historical 60 to110...

  6. The effects of downy brome invasion on mule deer habitat

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Downy brome (Bromus tectorum), also widely known as cheatgrass, is a highly invasive exotic weed that has spread over millions of hectares of rangelands throughout the Intermountain West. Native to Eurasia, this early maturing annual provides a fine textured fuel that increases the chance, rate, sea...

  7. Characteristics that determine a successful squirreltail (Elymus elymoides)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The successful rehabilitation of degraded cheatgrass (Bromus tectorum) dominated Wyoming Big sagebrush (Artemisia tridentata spp. Wyomingensis) communities hinge on the establishment of long-lived perennial grasses. While we have been successful with using introduced perennial grasses (i.e. Siberian...

  8. Lignans from the rhizomes of Iris tectorum.

    PubMed

    Zhang, Chun-Lei; Wang, Yan; Liu, Yan-Fei; Liang, Dong; Hao, Zhi-You; Luo, Huan; Chen, Ruo-Yun; Yu, De-Quan

    2016-01-01

    Chemical examination of the ethanol extract of rhizomes of Iris tectorum led to the isolation and characterization of three new lignans, (7R,7'R,8S,8'S)-5'-methoxy-neo-olivil (1a), (7S,7'S,8R,8'R) -5'-methoxy-neo-olivil (1b), (7S,7'R,8S,8'S)-neo-olivil (2a), (7R,7'S,8R,8'R)-neo-olivil (2b), (7R,7'R,8S,8'S,7''S,8''S)-threo-neo-olivil-4'-O-8-guaiacylglycerol ether (3), together with six known ones (4-9). Among them, compounds 1 and 2 were found to be racemic mixtures, respectively, which were verified by chiral HPLC analysis, compound 3 was a new sesquineolignan. The structures were elucidated on the basis of extensive spectroscopic analysis. To our knowledge, this is the first report of lignan constituents isolated from I. tectorum. All compounds were evaluated for their cytotoxicity against five human tumor cell lines and none of them displayed significant toxicity in tested cell lines at a concentration of 10 μM. PMID:26625840

  9. Plant community resistance to invasion by Bromus species – the roles of community attributes, Bromus Interactions with plant communities, and Bromus traits

    USGS Publications Warehouse

    Chambers, Jeanne; Germino, Matthew; Belnap, Jayne; Brown, Cynthia; Schupp, Eugene W.; St. Clair, Samuel B

    2016-01-01

    The factors that determine plant community resistance to exotic annual Bromus species (Bromushereafter) are diverse and context specific. They are influenced by the environmental characteristics and attributes of the community, the traits of Bromus species, and the direct and indirect interactions of Bromus with the plant community. Environmental factors, in particular ambient and soil temperatures, have significant effects on the ability of Bromus to establish and spread. Seasonality of precipitation relative to temperature influences plant community resistance toBromus through effects on soil water storage, timing of water and nutrient availability, and dominant plant life forms. Differences among plant communities in how well soil resource use by the plant community matches resource supply rates can influence the magnitude of resource fluctuations due to either climate or disturbance and thus the opportunities for invasion. The spatial and temporal patterns of resource availability and acquisition of growth resources by Bromus versus native species strongly influence resistance to invasion. Traits of Bromus that confer a “priority advantage” for resource use in many communities include early-season germination and high growth and reproductive rates. Resistance to Bromus can be overwhelmed by high propagule supply, low innate seed dormancy, and large, if short-lived, seed banks. Biological crusts can inhibit germination and establishment of invasive annual plants, including several annual Bromus species, but are effective only in the absence of disturbance. Herbivores can have negative direct effects on Bromus, but positive indirect effects through decreases in competitors. Management strategies can be improved through increased understanding of community resistance to exotic annual Bromus species.

  10. Simulating effects of cheatgrass invasion on native bunchgrass productivity under different precipitation scenarios

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Preventing the spread of cheatgrass is a high priority for natural resource managers in the western United States. Cheatgrass invasion is deleterious in numerous ways, including diminishing local biodiversity, increasing fire risks, and lowering carrying capacity. Because management is expensive, ...

  11. Small mammals of a bitterbrush-cheatgrass community

    SciTech Connect

    Gano, K.A.; Rickard, W.H.

    1982-01-01

    Small mammals were live-trapped in burned and unburned segments of a bitterbrush-cheatgrass community during the years 1974-1979. Results indicate that the shrub-dominated unburned area supports about three times as many small mammals as the cheatgrass-dominated burned area. Species composition was similar in both areas with the exception of one ground squirrel (Spermophilus townsendii) captured on the unburned area. Other species caught were the Great Basin pocket mouse (Perognathus parvus), deer mouse (Peromyscus maniculatus), northern grasshopper mouse (Onychomys leucogaster), and the western harvest mouse (Reithrodontomys megalotis).

  12. Pre-fire grazing by cattle increases postfire resistance to exotic annual grass (Bromus tectorum) invasion and dominance for decades

    Technology Transfer Automated Retrieval System (TEKTRAN)

    1. Fire, herbivory and their interaction influence plant community dynamics. However, little is known about the influence of pre-fire herbivory on post-fire plant community response, particularly long-term resilience to post-fire exotic plant invasion in areas that historically experienced limited ...

  13. Effects of resource availability and propagule supply on native species recruitment in sagebrush ecosystems invaded by Bromus tectorum

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Resource availability and propagule supply are major factors influencing establishment and persistence of both native and invasive species. Increased soil nitrogen availability and high propagule inputs contribute to the ability of annual invasive grasses to dominate disturbed ecosystems. Nitrogen r...

  14. Control of Downy brome (Bromus tectorum) and Medusahead (Taeniatherum caput-medusae) With Rangeland Herbicides in Northeastern California

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Downy brome and medusahead are the most problematic invasive annual grasses in rangelands of the western United States. In this study, we evaluated the effect of three fall-applied, and one spring-applied, herbicides or combinations on the control of these two invasive grasses in a sagebrush communi...

  15. Seeding Cool-Season Grasses to Suppress Broom Snakeweed (Gutierrezia sarothrae), Downy Brome (Bromus tectorum), and Weedy Forbs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Broom snakeweed is an aggressive native range weed found throughout semi-arid areas of the western U.S., and increases following disturbances such as overgrazing, drought, or wildfires. Ecologically based strategies that include controlling snakeweed and reestablishing desirable herbaceous species a...

  16. Resilience to stress and disturbance, and resistance to Bromus tectorum l. invasion in cold desert shrublands of western North America

    USGS Publications Warehouse

    Chambers, Jeanne C.; Bradley, Bethany A.; Brown, Cynthia S.; D'Antonio, Carla; Germino, Matthew J.; Grace, James B.; Hardegree, Stuart P.; Miller, Richard F.; Pyke, David A.

    2013-01-01

    Alien grass invasions in arid and semi-arid ecosystems are resulting in grass–fire cycles and ecosystem-level transformations that severely diminish ecosystem services. Our capacity to address the rapid and complex changes occurring in these ecosystems can be enhanced by developing an understanding of the environmental factors and ecosystem attributes that determine resilience of native ecosystems to stress and disturbance, and resistance to invasion. Cold desert shrublands occur over strong environmental gradients and exhibit significant differences in resilience and resistance. They provide an excellent opportunity to increase our understanding of these concepts. Herein, we examine a series of linked questions about (a) ecosystem attributes that determine resilience and resistance along environmental gradients, (b) effects of disturbances like livestock grazing and altered fire regimes and of stressors like rapid climate change, rising CO2, and N deposition on resilience and resistance, and (c) interacting effects of resilience and resistance on ecosystems with different environmental conditions. We conclude by providing strategies for the use of resilience and resistance concepts in a management context. At ecological site scales, state and transition models are used to illustrate how differences in resilience and resistance influence potential alternative vegetation states, transitions among states, and thresholds. At landscape scales management strategies based on resilience and resistance—protection, prevention, restoration, and monitoring and adaptive management—are used to determine priority management areas and appropriate actions.

  17. Do cheatgrass, snake river wheatgrass, and crested wheatgrass sense different availabilities of N and P in soils conditioned by a cheatgrass invasion?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Long-term invasion by cheatgrass often increases availability of soil N and P thereby fostering increased competitive ability. We designed an experiment to test if cheatgrass (exotic annual), Snake River wheatgrass (native perennial), and crested wheatgrass (exotic perennial) all benefit from this e...

  18. Conversion of sagebrush shrublands to exotic annual grasslands negatively impacts small mammal communities

    USGS Publications Warehouse

    Ostoja, S.M.; Schupp, E.W.

    2009-01-01

    Aim The exotic annual cheatgrass (Bromus tectorum) is fast replacing sagebrush (Artemisia tridentata) communities throughout the Great Basin Desert and nearby regions in the Western United States, impacting native plant communities and altering fire regimes, which contributes to the long-term persistence of this weedy species. The effect of this conversion on native faunal communities remains largely unexamined. We assess the impact of conversion from native perennial to exotic annual plant communities on desert rodent communities. Location Wyoming big sagebrush shrublands and nearby sites previously converted to cheatgrass-dominated annual grasslands in the Great Basin Desert, Utah, USA. Methods At two sites in Tooele County, Utah, USA, we investigated with Sherman live trapping whether intact sagebrush vegetation and nearby converted Bromus tectorum-dominated vegetation differed in rodent abundance, diversity and community composition. Results Rodent abundance and species richness were considerably greater in sagebrush plots than in cheatgrass-dominated plots. Nine species were captured in sagebrush plots; five of these were also trapped in cheatgrass plots, all at lower abundances than in the sagebrush. In contrast, cheatgrass-dominated plots had no species that were not found in sagebrush. In addition, the site that had been converted to cheatgrass longer had lower abundances of rodents than the site more recently converted to cheatgrass-dominated plots. Despite large differences in abundances and species richness, Simpson's D diversity and Shannon-Wiener diversity and Brillouin evenness indices did not differ between sagebrush and cheatgrass-dominated plots. Main conclusions This survey of rodent communities in native sagebrush and in converted cheatgrass-dominated vegetation suggests that the abundances and community composition of rodents may be shifting, potentially at the larger spatial scale of the entire Great Basin, where cheatgrass continues to invade

  19. Simulating Effects of Cheatgrass Invasion on Native Bunchgrass Productivity Under Different Precipitation Scenarios

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Preventing the spread of cheatgrass is a high priority for natural resource managers in the western United States. Cheatgrass invasion is deleterious in numerous ways, including diminishing local biodiversity, increasing fire risks, and lowering carrying capacity. Because management is expensive, it...

  20. Innovative techniques for weakening cheatgrass-wildfire feedbacks in the Colorado Plateau and the Great Basin

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Millions of hectares in the western United States have been negatively impacted by cheatgrass invasion, which transforms high-function ecosystems providing many ecosystem services into low-functioning areas. Once invasion begins, cheatgrass litter fuels increased wildfire frequency and extent, and w...

  1. The fitness costs of delayed germination and diminutive growth response of cheatgrass

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The competitive ability of cheatgrass is often attributed to rapid early season germination. Our previous research has observed germination occurring from October through June near the Reno, Nevada ARS research location. In a controlled experiment we allowed cheatgrass to germinate naturally (Octo...

  2. Self-revegetation of disturbed ground in the deserts of Nevada and Washington

    SciTech Connect

    Rickard, W.H.; Sauer, R.H.

    1982-01-01

    Plant cover established without purposeful soil preparation or seeding was measured on ground disturbed by plowing in Washington and by aboveground nuclear explosions in Nevada. After a time lapse of three decades in Washington and two decades in Nevada, fewer species were self-established on the disturbed ground than the nearby undisturbed ground. Alien annual plants were the dominants on the disturbed ground. Cheatgrass (Bromus tectorum) dominated abandoned fields in Washington, and filaree (Erodium cicutarium) dominated disturbed ground in Nevada. Perennial grasses and shrubs appeared to be more successful as invaders in Nevada than in Washington. This distinction is attributed to the superior competitive ability of cheatgrass in Washington.

  3. Hydrothermal emergence model for ripgut brome (Bromus diandrus)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A model that describes the emergence of ripgut brome (Bromus diandrus) was developed using a two-season data set from a no-tilled field in northeastern Spain. The relationship between cumulative emergence and hydrothermal time (HTT) was described by a sigmoid growth function (Chapman equation). HTT ...

  4. The invasive annual cheatgrass releases more nitrogen than crested wheatgrass through root exudation and senescence.

    PubMed

    Morris, Kendalynn A; Stark, John M; Bugbee, Bruce; Norton, Jeanette M

    2016-08-01

    Plant-soil feedbacks are an important aspect of invasive species success. One type of feedback is alteration of soil nutrient cycling. Cheatgrass invasion in the western USA is associated with increases in plant-available nitrogen (N), but the mechanism for this has not been elucidated. We labeled cheatgrass and crested wheatgrass, a common perennial grass in western rangelands, with (15)N-urea to determine if differences in root exudates and turnover could be a mechanism for increases in soil N. Mesocosms containing plants were either kept moist, or dried out during the final 10 days to determine the role of senescence in root N release. Soil N transformation rates were determined using (15)N pool dilution. After 75 days of growth, cheatgrass accumulated 30 % more total soil N and organic carbon than crested wheatgrass. Cheatgrass roots released twice as much N as crested wheatgrass roots (0.11 vs. 0.05 mg N kg(-1) soil day(-1)) in both soil moisture treatments. This occurred despite lower root abundance (7.0 vs. 17.3 g dry root kg(-1) soil) and N concentration (6.0 vs. 7.6 g N kg(-1) root) in cheatgrass vs. crested wheatgrass. We propose that increases in soil N pool sizes and transformation rates under cheatgrass are caused by higher rates of root exudation or release of organic matter containing relatively large amounts of labile N. Our results provide the first evidence for the underlying mechanism by which the invasive annual cheatgrass increases N availability and establishes positive plant-soil feedbacks that promote its success in western rangelands. PMID:26796411

  5. Negative Effects of an Exotic Grass Invasion on Small-Mammal Communities

    PubMed Central

    Freeman, Eric D.; Sharp, Tiffanny R.; Larsen, Randy T.; Knight, Robert N.; Slater, Steven J.; McMillan, Brock R.

    2014-01-01

    Exotic invasive species can directly and indirectly influence natural ecological communities. Cheatgrass (Bromus tectorum) is non-native to the western United States and has invaded large areas of the Great Basin. Changes to the structure and composition of plant communities invaded by cheatgrass likely have effects at higher trophic levels. As a keystone guild in North American deserts, granivorous small mammals drive and maintain plant diversity. Our objective was to assess potential effects of invasion by cheatgrass on small-mammal communities. We sampled small-mammal and plant communities at 70 sites (Great Basin, Utah). We assessed abundance and diversity of the small-mammal community, diversity of the plant community, and the percentage of cheatgrass cover and shrub species. Abundance and diversity of the small-mammal community decreased with increasing abundance of cheatgrass. Similarly, cover of cheatgrass remained a significant predictor of small-mammal abundance even after accounting for the loss of the shrub layer and plant diversity, suggesting that there are direct and indirect effects of cheatgrass. The change in the small-mammal communities associated with invasion of cheatgrass likely has effects through higher and lower trophic levels and has the potential to cause major changes in ecosystem structure and function. PMID:25269073

  6. Negative effects of an exotic grass invasion on small-mammal communities.

    PubMed

    Freeman, Eric D; Sharp, Tiffanny R; Larsen, Randy T; Knight, Robert N; Slater, Steven J; McMillan, Brock R

    2014-01-01

    Exotic invasive species can directly and indirectly influence natural ecological communities. Cheatgrass (Bromus tectorum) is non-native to the western United States and has invaded large areas of the Great Basin. Changes to the structure and composition of plant communities invaded by cheatgrass likely have effects at higher trophic levels. As a keystone guild in North American deserts, granivorous small mammals drive and maintain plant diversity. Our objective was to assess potential effects of invasion by cheatgrass on small-mammal communities. We sampled small-mammal and plant communities at 70 sites (Great Basin, Utah). We assessed abundance and diversity of the small-mammal community, diversity of the plant community, and the percentage of cheatgrass cover and shrub species. Abundance and diversity of the small-mammal community decreased with increasing abundance of cheatgrass. Similarly, cover of cheatgrass remained a significant predictor of small-mammal abundance even after accounting for the loss of the shrub layer and plant diversity, suggesting that there are direct and indirect effects of cheatgrass. The change in the small-mammal communities associated with invasion of cheatgrass likely has effects through higher and lower trophic levels and has the potential to cause major changes in ecosystem structure and function. PMID:25269073

  7. Increased Primary Production from an Exotic Invader Does Not Subsidize Native Rodents.

    PubMed

    Lucero, Jacob E; Allen, Phil S; McMillan, Brock R

    2015-01-01

    Invasive plants have tremendous potential to enrich native food webs by subsidizing net primary productivity. Here, we explored how a potential food subsidy, seeds produced by the aggressive invader cheatgrass (Bromus tectorum), is utilized by an important guild of native consumers--granivorous small mammals--in the Great Basin Desert, USA. In a series of field experiments we examined 1) how cheatgrass invasion affects the density and biomass of seed rain at the ecosystem-level; 2) how seed resources from cheatgrass numerically affect granivorous small mammals; and 3) how the food preferences of native granivores might mediate the trophic integration of cheatgrass seeds. Relative to native productivity, cheatgrass invasion increased the density and biomass of seed rain by over 2000% (P < 0.01) and 3500% (P < 0.01), respectively. However, granivorous small mammals in native communities showed no positive response in abundance, richness, or diversity to experimental additions of cheatgrass seeds over one year. This lack of response correlated with a distinct preference for seeds from native grasses over seeds from cheatgrass. Our experiments demonstrate that increased primary productivity associated with exotic plant invasions may not necessarily subsidize consumers at higher trophic levels. In this context, cheatgrass invasion could disrupt native food webs by providing less-preferred resources that fail to enrich higher trophic levels. PMID:26244345

  8. Increased Primary Production from an Exotic Invader Does Not Subsidize Native Rodents

    PubMed Central

    Lucero, Jacob E.; Allen, Phil S.; McMillan, Brock R.

    2015-01-01

    Invasive plants have tremendous potential to enrich native food webs by subsidizing net primary productivity. Here, we explored how a potential food subsidy, seeds produced by the aggressive invader cheatgrass (Bromus tectorum), is utilized by an important guild of native consumers – granivorous small mammals – in the Great Basin Desert, USA. In a series of field experiments we examined 1) how cheatgrass invasion affects the density and biomass of seed rain at the ecosystem-level; 2) how seed resources from cheatgrass numerically affect granivorous small mammals; and 3) how the food preferences of native granivores might mediate the trophic integration of cheatgrass seeds. Relative to native productivity, cheatgrass invasion increased the density and biomass of seed rain by over 2000% (P < 0.01) and 3500% (P < 0.01), respectively. However, granivorous small mammals in native communities showed no positive response in abundance, richness, or diversity to experimental additions of cheatgrass seeds over one year. This lack of response correlated with a distinct preference for seeds from native grasses over seeds from cheatgrass. Our experiments demonstrate that increased primary productivity associated with exotic plant invasions may not necessarily subsidize consumers at higher trophic levels. In this context, cheatgrass invasion could disrupt native food webs by providing less-preferred resources that fail to enrich higher trophic levels. PMID:26244345

  9. Cheatgrass invasion “engineers” the soil to facilitate its growth

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We tested the hypothesis that, over-time, cheatgrass occupation of a site, “engineers” the soil such that it is more favorable to its own growth. Testing was done in a greenhouse using rhizotrons (30 x 6 x 100 cm). Eight replicates each were filled with either freshly-collected soil occupied by wint...

  10. Evaluation of Radical Scavenging Activity of Sempervivum tectorum and Corylus avellana Extracts with Different Phenolic Composition.

    PubMed

    Alberti, Ágnes; Riethmüller, Eszter; Béni, Szabolcs; Kéry, Ágnes

    2016-04-01

    Semnpervivum tectorum L. and Corylus avellana L. are traditional herbal remedies exhibiting antioxidant activity and representing diverse phenolic composition. The aim of this study was to reveal the contribution of certain compounds to total radical scavenging activity by studying S. tectorum and C. avellana extracts prepared with solvents of different selectivity for diverse classes of phenolics. Antioxidant activity of S. tectorum and C. avellana samples was determined in the ABTS and DPPH radical scavenging assays, and phenolic composition was evaluated by high-performance liquid chromatography/electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS). Correlations between antioxidant activity and phenolic content of houseleek extracts have been revealed. Significant differences regarding antioxidant activity have been shown between S. tectorum 80% (v/v) methanol extract and its fractions. Additionally, synergism among the constituents present together in the whole extract was assumed. Significantly higher radical scavenging activity of hazel extracts has been attributed to the differences in phenolic composition compared with houseleek extracts. PMID:27396195

  11. The integration of geophysical and enhanced Moderate Resolution Imaging Spectroradiometer Normalized Difference Vegetation Index data into a rule-based, piecewise regression-tree model to estimate cheatgrass beginning of spring growth

    USGS Publications Warehouse

    Boyte, Stephen P.; Wylie, Bruce K.; Major, Donald J.; Brown, Jesslyn F.

    2015-01-01

    Cheatgrass exhibits spatial and temporal phenological variability across the Great Basin as described by ecological models formed using remote sensing and other spatial data-sets. We developed a rule-based, piecewise regression-tree model trained on 99 points that used three data-sets – latitude, elevation, and start of season time based on remote sensing input data – to estimate cheatgrass beginning of spring growth (BOSG) in the northern Great Basin. The model was then applied to map the location and timing of cheatgrass spring growth for the entire area. The model was strong (R2 = 0.85) and predicted an average cheatgrass BOSG across the study area of 29 March–4 April. Of early cheatgrass BOSG areas, 65% occurred at elevations below 1452 m. The highest proportion of cheatgrass BOSG occurred between mid-April and late May. Predicted cheatgrass BOSG in this study matched well with previous Great Basin cheatgrass green-up studies.

  12. Comparisons among species composition, leaf area, and water relations in three shrub-steppe plant communities

    SciTech Connect

    Link, S.O.; Kirkham, R.R.; Thiede, M.E.; Downs, J.L.; Gee, G.W.

    1987-03-01

    Observations were made on plant communities dominated by Bromus tectorum (cheatgrass site), Artemisia tridentata (sagebrush site), and Grayia spinosa (hopsage site). Leaf area on a ground area basis of sagebrush was nor significantly different between the sagebrush and hopsage sites; however, the leaf area of hopsage was one-quarter that of sagebrush at the hopsage site. Pre-dawn xylem water potential of sagebrush was -2.91 MPa, while that of hopsage was -4.79 MPa. Stomatal conductance and transpiration rate of sagebrush and hopsage were nearly the same. 11 refs., 4 figs., 2 tabs.

  13. Detecting Cheatgrass on the Colorado Plateau using Landsat data: A tutorial for the DESI software

    USGS Publications Warehouse

    Kokaly, Raymond F.

    2011-01-01

    Invasive plant species disrupt native ecosystems and cause economic harm to public lands. In this report, an example of applying the Detection of Early Season Invasives software to mapping cheatgrass infestations is given. A discussion of each step of the DESI process is given, including selection of Landsat images. Tutorial data, covering a semi-arid area in southern Utah, are distributed with this report. Tips on deriving the inputs required to run DESI are provided. An approach for evaluating and adjusting detection parameters by examining interim products of DESI is discussed.

  14. Karyotype and C-Banding Patterns of Mitotic Chromosomes in Meadow Bromegrass (Bromus riparius Rehm)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Chromosomes of meadow bromegrass, Bromus riparius, are mainly median and similar in morphology. C-bands were located at telomeric regions of the chromosomes. Majority of the chromosomes had telomeric bands either in one or both arms. Approximately 10 chromosomes had no C-bands. Karyotype of meadow b...

  15. SEASONALITY OF ANNUAL PLANT ESTABLISHMENT INFLUENCES THE INTERACTIONBETWEEN THE NON-NATIVE ANNUAL GRASS BROMUS MADRITENSIS SSP. RUBENS AND MOJAVE DESERT PERENNIALS

    SciTech Connect

    L A. DEFALCO; G. C. FERNANDEZ; R. S. NOWAK

    2004-01-01

    Competition between native and non-native species can change the composition and structure of plant communities, but in deserts the timing of non-native plant establishment can modulate their impacts to native species. In a field experiment, we varied densities of the non-native annual grass Bromus madritensis ssp. rubens around individuals of three native perennials--Larrea iridentata, Achnatherum hymenoides, and Pleuraphis rigida--in either winter or spring. Additional plots were prepared for the Same perennial species and seasons, but with a mixture of native annual species. Relative growth rates of perennial shoots (RGRs) declined with increasing Bromus biomass when Bromus that was established in winter had 2-3 mo of growth and high water use before perennial growth began. However, this high water use did not significantly reduce water potentials for the perennials, suggesting Bromus that established earlier depleted other soil resources, such as N, otherwise used by perennial plants. Spring-established Bromus had low biomass even at higher densities and did not effectively reduce RGRs, resulting in an overall lower impact to perennials than when Bromus was established in winter. Similarly, growth and reproduction of perennials with mixed annuals as neighbors did not differ from those with Bromus neighbors of equivalent biomass, but densities of these annuals did not support the high biomass necessary to reduce perennial growth. Thus, impacts of native Mojave Desert annuals to perennials are expected to be lower than those of Bromus because seed dormancy and narrow requirements for seedling survivorship produce densities and biomass lower than those achieved by Bromus. In comparing the effects of Bromus among perennial species, the impact of increased Bromus biomass on RGR was lower for Larrea than for the two perennial grasses, probably because Lurrea maintains low growth rates throughout the year, even after Bromus has completed its life cycle. This contrasts

  16. The Jasper Ridge elevated CO{sub 2} experiment: Root acid phosphatase activity in Bromus hordeaceus and Avena barbata remains unchanged under elevated [CO{sub 2}

    SciTech Connect

    Cardon, Z.G.; Jackson, R.

    1995-06-01

    Root acid phosphatase activity increases phosphate available to plants by cleaving phosphate esters in soil organic matter. Because of increased plant growth potential under elevated [CO{sub 2}], we hypothesized that high [CO{sub 2}]-grown plants might exhibit higher phosphatase activity than low [CO{sub 2}]-grown plants. We assayed phosphatase activity in two species grown on two substrates (Bromus on serpentine soil and Bromus and Avena on sandstone soil) under high and low [CO{sub 2}] and under several nutrient treatments. Phosphatase activity was expressed per gram fresh weight of roots. Phosphatase activity of Bromus roots (on sandstone) was first assayed in treatments where only P and K, or only N, were added to soil. Bromus roots in this case showed strong induction of phosphatase activity when N only had been added to soil, indicating that Bromus regulated its phosphatase activity in response to phosphate availability. Both Bromus and Avena growing in sandstone, and Bromus growing in serpentine, showed enhanced phosphatase activity at high nutrient (N, P, and K) levels over that at low nutrient levels, but no differences between phosphatase activity were apparent between [CO{sub 2}] treatments. The increased phosphatase activity at high N, P, and K may indicate enhanced {open_quotes}growth demand{close_quotes} (reflected in higher biomass) in both Avena and Bromus. In contrast, though Bromus {open_quotes}growth demand{close_quotes} (biomass) increased under high [CO{sub 2}] on sandstone, phosphatase activity did not increase.

  17. [Cartography and geographical spread of the adventitious species of brome (Bromus spp.) among cereals in the Sais area of Morocco].

    PubMed

    Hamal, A; Benbella, M; Rzozi, S B; Bouhache, M; Msatef, Y

    2001-01-01

    Bromus spp is causing serious problems in wheat in the Sais area. However, the damage of this weed varies from one region to another according to the agro-climatic conditions and crop systems. The characterization of the infestation level in each situation is a prerequisite to develop a control strategy adapted to each environment. This study was undertaken in order to determine the infestation level and geographical spread of the weedy brome (Bromus spp) on wheat in Sais following crop systems and pedo-climatic conditions. The results obtained during two consecutive years (1998-99 and 1999-2000) revealed that ripgut brome (Bromus rigidus Roth.) was the most dominant species in wheat fields in the surveyed regions, followed by B. rubens L., B. sterilis L., B. madritensis L. and B. mollus L. Among, 18 regions and 100 infested wheat fields, 16.67% of fields were slightly infested (Plant density of Bromus (Dbr < 90 plants/m2, 61.11% were moderately infested (90 < Dbr < 290 plants/m2) and 22.22% were highly infested (Dbr > 400 plants/m2). The maximum relative frequency was obtained with Bromus rigidus (47.15%) and the coverage was 40.43%. But, for B.rubens, B. madritensis and B. sterilis, the relative frequencies were respectively 31.42; 26 and 15% and their coverages were respectively 28.9, 20.4 and 12.5%. PMID:12425101

  18. Polycycloiridals A-D, Four Iridal-Type Triterpenoids with an α-Terpineol Moiety from Iris tectorum.

    PubMed

    Zhang, Chun-Lei; Liu, Yan-Fei; Wang, Yan; Liang, Dong; Jiang, Zhi-Bo; Li, Li; Hao, Zhi-You; Luo, Huan; Shi, Guo-Ru; Chen, Ruo-Yun; Cao, Zheng-Yu; Yu, De-Quan

    2015-11-20

    Polycycloiridals A-D, four novel iridals with an unprecedented α-terpineol moiety resulting from cyclization of the homofarnesylside chain, were isolated from the ethanol extract of rhizomes of Iris tectorum. Their structures were elucidated on the basis of comprehensive spectroscopic analysis. The absolute configuration of 1 was determined by the modified Mosher's method and comparison of experimental and calculated electronic circular dichroism (ECD) spectrum. A possible biosynthetic pathway was postulated. PMID:26555865

  19. Mapping genetic variation and seed zones for Bromus carinatus in the Blue Mountains of eastern Oregon, USA.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Genecology studies using regression models to develop plant adaptation zones are useful to ensure that germplasm selected for revegetation is environmentally adapted. In this study, genecology studies were completed on Mt. Brome (Bromus carinatus Hook. & Arn ) using 148 populations collected in the...

  20. A regional analysis of drivers and impacts of land cover change and long-term land cover trends in the Great Basin, United States

    NASA Astrophysics Data System (ADS)

    Bradley, Bethany Adella

    An improved understanding of land use/land cover change at local and regional scales is important in an increasingly human-dominated biosphere. The land surface provides resources necessary for human survival (e.g., cropland, water, raw materials) as well as providing other services such as habitat for native species, carbon storage, and nutrient cycling. A goal of land change science is to identify where land cover change is taking place, understand how land use may affect that change, and determine what the consequences of change may be. In the Great Basin Desert of the Western U.S., an important form of land cover change is invasion by non-native cheatgrass (Bromus tectorum). Cheatgrass invasion destroys native shrub ecosystems, leading to a loss of biodiversity, loss of viable rangeland and increased fire frequency. In this work, I show how remote sensing can be used to detect the regional and local extents of cheatgrass invasion. Remote sensing results are then used to assess the spatial patterns of cheatgrass invasion over time to determine how land use might have affected invasion. Further, I consider the long-term impacts of cheatgrass invasion on biodiversity and carbon storage in the Great Basin. In addition to an analysis of cheatgrass, this thesis presents a new methodology for time series modeling, which can be used to better interpret annual and inter-annual vegetation community phenology. I apply this modeling methodology to all land cover in the Great Basin to assess long-term land cover trends and localized anomalous response within the range of land cover classes present. By investigating regional land cover change I am able to provide more detailed analysis of the drivers of change for land managers while working at a scale relevant to studies of global environmental change.

  1. Effects of mating system on adaptive potential for leaf morphology in Crepis tectorum (Asteraceae)

    PubMed Central

    Andersson, Stefan; Ofori, Jones K.

    2013-01-01

    Background and Aims A shift from outcrossing to selfing is thought to reduce the long-term survival of populations by decreasing the genetic variation necessary for adaptation to novel ecological conditions. However, theory also predicts an increase in adaptive potential as more of the existing variation becomes expressed as homozygous genotypes. So far, relatively few studies have examined how a transition to selfing simultaneously affects means, variances and covariances for characters that might be under stabilizing selection for a spatially varying optimum, e.g. characters describing leaf morphology. Methods Experimental crosses within an initially self-sterile population of Crepis tectorum were performed to produce an outbred and inbred progeny population to assess how a shift to selfing affects the adaptive potential for measures of leaf morphology, with special emphasis on the degree of leaf dissection, a major target of diversifying selection within the study species. Key Results Three consecutive generations of selfing had a minor impact on survival, the total number of heads produced and the mean leaf phenotype, but caused a proportional increase in the genetic (co)variance matrix for foliar characters. For the degree of leaf dissection, the lowest 50th percentile of the inbred progeny population showed a disproportionate increase in the genetic variance, consistent with the recessive nature of the weakly lobed phenotype observed in interpopulation crosses. Comparison of inbreeding response with large-scale patterns of variation indicates a potential for selection in a (recently) inbred population to drive a large evolutionary reduction in degree of leaf dissection by increasing the frequency of particular sibling lines. Conclusions The results point to a positive role for inbreeding in phenotypic evolution, at least during or immediately after a rapid shift in mating system. PMID:23912696

  2. Allelopathic effect of Bromus spp. and Lolium spp. shoot extracts on some crops.

    PubMed

    Lehoczky, E; Nelima, M Okumu; Szabó, R; Szalai, A; Nagy, P

    2011-01-01

    Allelopathy is an untapped resource for weed control in crops that could give good possibilities for environmentally sound, integrated crop production. Allelopathy is defined as the direct or indirect harmful or beneficial effects of one plant on another through the production of chemical compounds, called allelochemicals, which escape into the environment. Allelochemicals can be produced by weeds and affect crops, and the reverse is also true. Allelopathic interactions include weed-weed, weed-crop, and crop-crop. Allelopathy offers potential for selective biological weed control for instance weed-suppressing crops and the use of plant residues in cropping systems, allelopathic rotational crops, or companion plants with allelopathic potential. Bromus species occur in many habitats in temperate regions of the world, including America, Eurasia, Australia, and Africa. The genus Lolium is one of the most important forage grasses. The weed species usually grow in the same production zones as wheat and are considered weeds since they parasitize wheat fields. Some of the weed species in these two genus have been reported to have allelopathic effect. One of the methods that has been successful in studying allelopathic activity are bioassays. Laboratory experiments were conducted to determine allelopathic effect of watery shoot extracts of four weed species of the Poaceae family, namely Bromus rigidus, Bromus diandrus, Lolium multiflorum and Lolium temulentum on germination and growth of winter wheat (Triticum aestivum L.), spring barley (Hordeum vulgare L.), corn (Zea mays L), perennial ryegrass (Lolium perenne L.), bean (Phaseolus sp.) and sunflower (Helianthus annuus L.) and on each other. The experiment was carried out during the period March 2010 to October 2010. Twenty five seeds were put into one Petri-dish on filter paper, adding 15ml of extract to each in four repeats. The germination took place in a Binder-type thermostat in the dark. The timing of germination was

  3. Integrated control and assessment of knapweed and cheatgrass on Department of Defense installations. 2007 Annual Report/Final Report SI-1145

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We conducted field studies to control alien invasive weeds (cheatgrasses and knapweeds) at 3 military bases for 2 to 6 years. Four methods to accelerate natural plant succession were tested: 1) reducing the target weed population using biological control or burning, 2) reducing soil nitrogen availab...

  4. Feeding preference for and impact on an invasive weed (Crepis tectorum L.) by a native, generalist insect herbivore, Melanoplus borealis (Orthoptera: Acrididae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Crepis tectorum L., narrow leaf hawksbeard, was first collected in Alaska in 1974 and by 2004 was a common weed in agricultural fields. Introduction and establishment of a new plant species in a region represents a potential new resource for herbivores, as well as a new competitor for plant species ...

  5. Are Mojave Desert annual species equal? Resource acquisition and allocation for the invasive grass Bromus madritensis subsp. rubens (Poaceae) and two native species

    USGS Publications Warehouse

    DeFalco, L.A.; Bryla, D.R.; Smith-Longozo, V.; Nowak, R.S.

    2003-01-01

    Abundance of invasive plants is often attributed to their ability ot outcompete native species. We compared resource acquisition and allocation of the invasive annual grass Bromus madritensis subsp. rubens with that of two native Mojave Desert annuals, Vulpia octoflora and Descurainia pinnata, in a glasshouse experiment. Each species was grown in monoculture at two densities and two levels of N availability to compare how these annuals capture resources and to understand their relative sensitivities to environmental change. During >4 mo of growth, Bromus used water more rapidly and had greater biomass and N content than the natives, partly because of its greater root-surface area and its exploitation of deep soils. Bromus also had greater N uptake, net assimilation and transpiration rates, and canopy area than Vulpia. Resource use by Bromus was less sensitive to changes in N availability or density than were the natives. The two native species in this study produced numerous small seeds that tended to remain dormant, thus ensuring escape of offspring from unfavorable germination conditions; Bromus produced fewer but larger seeds that readily germinated. Collectively, these traits give Bromus the potential to rapidly establish in diverse habitats of the Mojave Desert, thereby gaining an advantage over coexisting native species.

  6. Exotic plant colonization and occupancy within riparian areas of the Interior Columbia River and Upper Missouri River basins, USA

    USGS Publications Warehouse

    Al-Chokhachy, Robert K.; Ray, Andrew M.; Roper, Brett B.; Archer, Eric

    2013-01-01

    Exotic plant invasions into riparia often result in shifts in vegetative composition, altered stream function, and cascading effects to biota at multiple scales. Characterizing the distribution patterns of exotic plants is an important step in directing targeted research to identify mechanisms of invasion and potential management strategies. In this study, we employed occupancy models to examine the associations of landscape, climate, and disturbance attributes with the colonization and occupancy patterns for spotted knapweed (Centaurea stoebe L.), Canada thistle (Cirsium arvense L., Scop.), and cheatgrass (Bromus tectorum L.) in the riparia of headwater streams (n = 1,091) in the Interior Columbia River and Upper Missouri River Basins. We found relatively low occupancy rates for cheatgrass (0.06, SE = 0.02) and spotted knapweed (0.04, SE = 0.01), but moderate occupancy of Canada thistle (0.28, SE = 0.05); colonization rates were low across all species (<0.01). We found the distributions of spotted knapweed, Canada thistle, and cheatgrass to exhibit significant associations with both ambient climate conditions and anthropogenic and natural disturbances. We attribute the low to moderate occupancy and colonization rates to the relatively remote locations of our sample sites within headwater streams and urge consideration of means to prevent further invasions.

  7. Born of fire - restoring sagebrush steppe

    USGS Publications Warehouse

    Pyke, David A.

    2002-01-01

    Fire is a natural feature of sagebrush grasslands in the Great Basin. The invasion of exotic annual grasses, such as Bromus tectorum (cheatgrass), has changed the environment in these ecosystems. Invasive annual grasses provide a dense and continuous source of fuel that extends the season for fires and increases the frequency of fires in the region. Frequent fires eventually eliminate the native sagebrush. These annual grasses also change soil nutrients, especially carbon and nitrogen, such that invasive annual grasses are favored over the native plants. The Forest and Rangeland Ecosystem Science Center of the U.S. Geological Survey (USGS) is studying how to reduce the problems caused by these invasive annual grasses and restore native sagebrush grasslands. The areas of research include understanding disturbance regimes, especially fire, discerning the role of nutrients in restoring native plants, determining the potential to restore forbs important for wildlife, and ascertaining the past and present use of native and nonnative plants in revegetation projects.

  8. UNMANNED AERIAL VEHICLE (UAV) HYPERSPECTRAL REMOTE SENSING FOR DRYLAND VEGETATION MONITORING

    SciTech Connect

    Nancy F. Glenn; Jessica J. Mitchell; Matthew O. Anderson; Ryan C. Hruska

    2012-06-01

    UAV-based hyperspectral remote sensing capabilities developed by the Idaho National Lab and Idaho State University, Boise Center Aerospace Lab, were recently tested via demonstration flights that explored the influence of altitude on geometric error, image mosaicking, and dryland vegetation classification. The test flights successfully acquired usable flightline data capable of supporting classifiable composite images. Unsupervised classification results support vegetation management objectives that rely on mapping shrub cover and distribution patterns. Overall, supervised classifications performed poorly despite spectral separability in the image-derived endmember pixels. Future mapping efforts that leverage ground reference data, ultra-high spatial resolution photos and time series analysis should be able to effectively distinguish native grasses such as Sandberg bluegrass (Poa secunda), from invasives such as burr buttercup (Ranunculus testiculatus) and cheatgrass (Bromus tectorum).

  9. Bird-habitat relationships in interior Columbia Basin shrubsteppe

    USGS Publications Warehouse

    Earnst, S.L.; Holmes, A.L.

    2012-01-01

    Vegetation structure is considered an important habitat feature structuring avian communities. In the sagebrush biome, both remotely-sensed and field-acquired measures of big sagebrush (Artemisia tridentata) cover have proven valuable in understanding avian abundance. Differences in structure between the exotic annual cheatgrass (Bromus tectorum) and native bunchgrasses are also expected to be important. We used avian abundance data from 318 point count stations, coupled with field vegetation measurements and a detailed vegetation map, to model abundance for four shrub- and four grassland-associated avian species in southeastern Washington shrubsteppe. Specifically, we ask whether species distinguish between bunchgrass and cheatgrass, and whether mapped, categorical cover types adequately explain species' abundance or whether fine-grained, field-measured differences in vegetation cover are also important. Results indicate that mapped cover types alone can be useful for predicting patterns of distribution and abundance within the sagebrush biome for several avian species (five of eight studied here). However, field-measured sagebrush cover was a strong positive predictor for Sage Sparrow (Amphispiza belli), the only sagebrush obligate in this study, and a strong negative predictor for two grassland associates, Horned Lark (Eremophila alpestris) and Grasshopper Sparrow (Ammodramus savannarum). Likewise, shrub associates did not differ in abundance in sagebrush with a cheatgrass vs. bunchgrass understory, but grassland associates were more common in either bunchgrass (Horned Lark and Grasshopper Sparrow) or cheatgrass grasslands (Long-billed Curlew, Numenius americanus), or tended to use sagebrush-cheatgrass less than sagebrush-bunchgrass (Horned Lark, Grasshopper Sparrow, and Savannah Sparrow, Passerculus sandwichensis).

  10. Karyotype and nuclear DNA content of hexa-, octo-, and duodecaploid lines of Bromus subgen. Ceratochloa

    PubMed Central

    2009-01-01

    The subgenus Ceratochloa of the genus Bromus includes a number of closely related allopolyploid forms or species that present a difficult taxonomic problem. The present work combines data concerning chromosome length, heterochromatin distribution and nuclear genome size of different 6x, 8x and 12x accessions in this subgenus. Special attention is paid to the karyotype structure and genomic constitution of duodecaploid plants recently found in South America. Hexaploid lineages possess six almost indistinguishable genomes and a nuclear DNA content between 12.72 pg and 15.10 pg (mean 1Cx value = 2.32 pg), whereas octoploid lineages contain the same six genomes (AABBCC) plus two that are characterized by longer chromosomes and a greater DNA content (1Cx = 4.47 pg). Two duodecaploid accessions found in South America resemble each other and apparently differ from the North American duodecaploid B. arizonicus as regards chromosome size and nuclear DNA content (40.00 and 40.50 pg vs. 27.59 pg). These observations suggest that the South American duodecaploids represent a separate evolutionary lineage of the B. subgenus Ceratochloa, unrecognized heretofore. PMID:21637516

  11. Identification of novel Bromus- and Trifolium-associated circular DNA viruses.

    PubMed

    Kraberger, Simona; Farkas, Kata; Bernardo, Pauline; Booker, Cameron; Argüello-Astorga, Gerardo R; Mesléard, François; Martin, Darren P; Roumagnac, Philippe; Varsani, Arvind

    2015-05-01

    The genomes of a large number of highly diverse novel circular DNA viruses from a wide range of sources have been characterised in recent years, including circular single-stranded DNA (ssDNA) viruses that share similarities with plant-infecting ssDNA viruses of the family Geminiviridae. Here, we describe six novel circular DNA viral genomes that encode replication-associated (Rep) proteins that are most closely related to those of either geminiviruses or gemycircularviruses (a new group of ssDNA viruses that are closely related to geminiviruses). Four possible viral genomes were recovered from Bromus hordeaceus sampled in New Zealand, and two were recovered from B. hordeaceus and Trifolium resupinatum sampled in France. Two of the viral genomes from New Zealand (one from the North Island and one from the South Island each) share >99 % sequence identity, and two genomes recovered from B. hordeaceus and T. resupinatum sampled in France share 74 % identity. All of the viral genomes that were recovered were found to have a major open reading frame on both their complementary and virion-sense strands, one of which likely encodes a Rep and the other a capsid protein. Although future infectivity studies are needed to identify the host range of these viruses, this is the first report of circular DNA viruses associated with grasses in New Zealand. PMID:25701210

  12. Red brome (Bromus rubens subsp. madritensis) in North America: Possible modes for early introductions, subsequent spread

    USGS Publications Warehouse

    Salo, L.F.

    2005-01-01

    Although invasions by exotic plants have increased dramatically as human travel and commerce have increased, few have been comprehensively described. Understanding the patterns of invasive species spread over space and time will help guide management activities and policy. Tracing the earliest appearances of an exotic plant reveals likely sites of introduction, paving the way for genetic studies to quantify founder events and identify potential source populations. Red brome (Bromus madritensis subsp. rubens) is a Mediterranean winter annual grass that has invaded even relatively undisturbed areas of western North America, where it threatens native plant communities. This study used herbarium records and contemporary published accounts to trace the early introductions and subsequent spread of red brome in western North America. The results challenge the most frequently cited sources describing the early history of this grass and suggest three possible modes for early introductions: the California Gold Rush and Central Valley wheat, southern California shipping, and northern California sheep. Subsequent periods of most rapid spread into new areas, from 1930 to 1942, and of greatest spread into new regions, during the past 50 years, coincide with warm Pacific Decadal Oscillation regimes, which are linked to increased winter precipitation in the southwestern USA and northern Mexico. Global environmental change, including increased atmospheric CO2 levels and N deposition, may be contributing to the success of red brome, relative to native species.

  13. Capillary zone electrophoretic determination of phenolic compounds in chess (Bromus inermis L.) plant extracts.

    PubMed

    Sterbová, Dagmar; Vlcek, Jirí; Kubán, Vlastimil

    2006-02-01

    A simple CZE method for quantification of phenolic compounds (vanillin, cinnamic, sinapic, chlorogenic, syringic, ferulic, benzoic, p-coumaric, vanillic, p-hydroxybenzoic, rosmarinic, caffeic, gallic and protocatechuic acids) in less than 10 min using 20 mM sodium tetraborate (pH 9.2) with 5% v/v methanol as a BGE and with UV detection at 254 nm is described. The LODs (3 S/N) ranged between 0.02 and 0.12 microg/ mL. Repeatabilities (RSDs) were 0.66-1.8 and 1.56-4.23% for migration times and peak areas (n = 5), respectively. The method was applied to the determination of phenolic compounds in chess (Bromus inermis L.) after Soxhlet extraction and purification of the crude extracts with SPE procedures. The results compared well with those obtained by liquid chromatographic method. B. inermis was found as a suitable model plant containing a broad spectrum of phenolic compounds in easily detectable concentrations and as a potential source of antioxidants. PMID:16524108

  14. Seed harvesting by a generalist consumer is context-dependent: Interactive effects across multiple spatial scales

    USGS Publications Warehouse

    Ostoja, Steven M.; Schupp, Eugene W.; Klinger, Rob

    2013-01-01

    Granivore foraging decisions affect consumer success and determine the quantity and spatial pattern of seed survival. These decisions are influenced by environmental variation at spatial scales ranging from landscapes to local foraging patches. In a field experiment, the effects of seed patch variation across three spatial scales on seed removal by western harvester ants Pogonomyrmex occidentalis were evaluated. At the largest scale we assessed harvesting in different plant communities, at the intermediate scale we assessed harvesting at different distances from ant mounds, and at the smallest scale we assessed the effects of interactions among seed species in local seed neighborhoods on seed harvesting (i.e. resource–consumer interface). Selected seed species were presented alone (monospecific treatment) and in mixture with Bromus tectorum (cheatgrass; mixture treatment) at four distances from P. occidentalis mounds in adjacent intact sagebrush and non-native cheatgrass-dominated communities in the Great Basin, Utah, USA. Seed species differed in harvest, with B. tectorum being least preferred. Large and intermediate scale variation influenced harvest. More seeds were harvested in sagebrush than in cheatgrass-dominated communities (largest scale), and the quantity of seed harvested varied with distance from mounds (intermediate-scale), although the form of the distance effect differed between plant communities. At the smallest scale, seed neighborhood affected harvest, but the patterns differed among seed species considered. Ants harvested fewer seeds from mixed-seed neighborhoods than from monospecific neighborhoods, suggesting context dependence and potential associational resistance. Further, the effects of plant community and distance from mound on seed harvest in mixtures differed from their effects in monospecific treatments. Beyond the local seed neighborhood, selection of seed resources is better understood by simultaneously evaluating removal at

  15. Repeated landscape-scale treatments following fire suppress a non-native annual grass and promote recovery of native perennial vegetation

    USGS Publications Warehouse

    Munson, Seth M.; Long, A. Lexine; Decker, Cheryl E.; Johnson, Katie A.; Walsh, Kathleen; Miller, Mark E.

    2015-01-01

    Invasive non-native species pose a large threat to restoration efforts following large-scale disturbances. Bromus tectorum (cheatgrass) is a non-native annual grass in the western U.S. that both spreads quickly following fire and accelerates the fire cycle. Herbicide and seeding applications are common restoration practices to break the positive fire-invasion feedback loop and recover native perennial species, but their interactive effects have infrequently been tested at the landscape-scale and repeated in time to encourage long-lasting effects. We determined the efficacy of repeated post-fire application of the herbicide imazapic and seeding treatments to suppressBromus abundance and promote perennial vegetation recovery. We found that the selective herbicide reduced Bromus cover by ~30 % and density by >50 % across our study sites, but had a strong initial negative effect on seeded species. The most effective treatment to promote perennial seeded species cover was seeding them alone followed by herbicide application 3 years later when the seeded species had established. The efficacy of the treatments was strongly influenced by water availability, as precipitation positively affected the density and cover of Bromus; soil texture and aspect secondarily influenced Bromus abundance and seeded species cover by modifying water retention in this semi-arid region. Warmer temperatures positively affected the non-native annual grass in the cool-season, but negatively affected seeded perennial species in the warm-season, suggesting an important role of seasonality in a region projected to experience large increases in warming in the future. Our results highlight the importance of environmental interactions and repeated treatments in influencing restoration outcomes at the landscape-scale.

  16. Impacts of Climate Variability on Non-native Plant Invasion in the Western U.S.

    NASA Astrophysics Data System (ADS)

    Bradley, B. A.

    2006-12-01

    Plant invasions are changing ecosystem structure and function throughout the United States. In many areas of the west, invasive species such as tamarisk (Tamarix spp.), cheatgrass (Bromus tectorum), and yellow starthistle (Centaurea solstitialis) dominate landscapes. Expansion of these species is occurring at a staggering rate, and invasion rates may change in the future as native ecosystems become more or less susceptible to invasion because of changes in climate. For example, evidence suggests that some plant invaders are favored under increased ambient CO2 levels, potentially leading to increased invasion with continued greenhouse gas emissions. In this work, I predict how western invasive plant species may also be affected by changes in climate variability. According to IPCC reports, rising ocean temperatures may change the frequency and intensity of El Niño events, potentially resulting in wetter El Niño years and/or more extreme and lengthier drought. In semi-arid systems, changing frequency or magnitude of extreme weather events may further shift the competitive balance between native and invasive species. For example, cheatgrass and yellow starthistle, both annual invaders, display high inter-annual variability in response to water availability. As a result, plants are larger and produce more seeds than native competitors during extreme wet years. This phenological response is so strong in cheatgrass communities that it can be observed in regional satellite records. Further, dense cheatgrass growth leads to a secondary feedback in the form of wildfire; higher density cheatgrass increases fire frequency in shrublands and enables further cheatgrass colonization. In this work, I synthesize knowledge of invasive plant phenological response under different climate conditions, drawing on information gathered through geographical mapping efforts at state or regional levels by university and agency researchers. Using the ranges of climate tolerance from current

  17. De novo Genome Assembly of the Fungal Plant Pathogen Pyrenophora semeniperda

    PubMed Central

    Soliai, Marcus M.; Meyer, Susan E.; Udall, Joshua A.; Elzinga, David E.; Hermansen, Russell A.; Bodily, Paul M.; Hart, Aaron A.; Coleman, Craig E.

    2014-01-01

    Pyrenophora semeniperda (anamorph Drechslera campulata) is a necrotrophic fungal seed pathogen that has a wide host range within the Poaceae. One of its hosts is cheatgrass (Bromus tectorum), a species exotic to the United States that has invaded natural ecosystems of the Intermountain West. As a natural pathogen of cheatgrass, P. semeniperda has potential as a biocontrol agent due to its effectiveness at killing seeds within the seed bank; however, few genetic resources exist for the fungus. Here, the genome of P. semeniperda isolate assembled from sequence reads of 454 pyrosequencing is presented. The total assembly is 32.5 Mb and includes 11,453 gene models encoding putative proteins larger than 24 amino acids. The models represent a variety of putative genes that are involved in pathogenic pathways typically found in necrotrophic fungi. In addition, extensive rearrangements, including inter- and intrachromosomal rearrangements, were found when the P. semeniperda genome was compared to P. tritici-repentis, a related fungal species. PMID:24475219

  18. Yield Responses of Ruderal Plants to Sucrose in Invasive-Dominated Sagebrush Steppe of the Northern Great Basin

    USGS Publications Warehouse

    Brunson, J.L.; Pyke, D.A.; Perakis, S.S.

    2010-01-01

    Restoration of sagebrush-steppe plant communities dominated by the invasive ruderals Bromus tectorum (cheatgrass) and Taeniatherum caput-medusae (medusahead) can be facilitated by adding carbon (C) to the soil, stimulating microbes to immobilize nitrogen (N) and limit inorganic N availability. Our objectives were to determine responses in (1) cheatgrass and medusahead biomass and seed production; (2) soil microbial biomass C and N; and (3) inorganic soil N to a range of C doses and to calculate the lowest dose that yielded a significant response. In November 2005, we applid 12 C doses ranging from 0 to 2,400 kg C/ha as sucrose to plots sown with cheatgrass and medusahead at two sites in the northern Great Basin. Other ruderal plants established in our plots, and this entire ruderal community was negatively affected by C addition. End-of-year biomass of the ruderal community decreased approximately by approximately 6% at each site for an increase in C dose of 100 kg C/ha. For the same increase in C, microbial biomass C increased by 2-4 mg/kg in November 2005 and March 2006, but not in July 2006. There was little, if any, microbial soil N uptake, as microbial biomass N increased by 0.3 mg/kg at only one site at the earliest date, in November 2005. Soil nitrate (NO3-) measured via resin capsules placed in situ for the study duration decreased at both sites with increasing C. Although we found no threshold dose of C, for a significant reduction in ruderal biomass, we calculated lowest significant doses of 240-640 kg C/ha. ?? 2010 Society for Ecological Restoration International.

  19. Natural succession impeded by smooth brome (Bromus inermis) and intermediate wheatgrass (Agropyron intermedium) in an abandoned agricultural field

    SciTech Connect

    Nelson, J.K.

    1997-11-01

    In 1975, an abandoned agricultural field at Rocky Flats Environmental Technology Site (Site) that had been cultivated for more than 38 years, was seeded with smooth brome (Bromus inermis) and intermediate wheatgrass (Agropyron intermedium). Although these species are commonly planted in reclamation and roadside seed mixtures, few studies have documented their impact on the re-establishment of native plant communities. In 1994, species richness, cover, and biomass were sampled in the agricultural field and compared to the surrounding mixed-grass prairie at the Site. The agricultural field contained only 61 plant species (62% native), compared to 143 species (81% native) in the surrounding mixed-grass prairie. Community similarity based on species presence/absence was 0.47 (Sorensen coefficient of similarity). Basal vegetative cover was 11.2% in the agricultural field and 29.1% in the mixed-grass prairie. Smooth brome and intermediate wheatgrass accounted for 93% of the relative foliar cover and 96% of the biomass in the agricultural field. The aggressive nature of these two planted species has impeded the natural succession of the agricultural field to a more native prairie community. Studies of natural succession on abandoned fields and roads in northeastern Colorado have indicated that if left alone, fields would return to their native climax state in approximately 50 years and would be approaching their native state after 20--25 years. Based on the results of this study, this agricultural field may take more than 100 years to return to a native mixed-grass prairie state and it may never achieve a native state without human intervention.

  20. A comparison of adaptive sampling designs and binary spatial models: A simulation study using a census of Bromus inermis

    USGS Publications Warehouse

    Irvine, Kathryn M.; Thornton, Jamie; Backus, Vickie M.; Hohmann, Matthew G.; Lehnhoff, Erik A.; Maxwell, Bruce D.; Michels, Kurt; Rew, Lisa

    2013-01-01

    Commonly in environmental and ecological studies, species distribution data are recorded as presence or absence throughout a spatial domain of interest. Field based studies typically collect observations by sampling a subset of the spatial domain. We consider the effects of six different adaptive and two non-adaptive sampling designs and choice of three binary models on both predictions to unsampled locations and parameter estimation of the regression coefficients (species–environment relationships). Our simulation study is unique compared to others to date in that we virtually sample a true known spatial distribution of a nonindigenous plant species, Bromus inermis. The census of B. inermis provides a good example of a species distribution that is both sparsely (1.9 % prevalence) and patchily distributed. We find that modeling the spatial correlation using a random effect with an intrinsic Gaussian conditionally autoregressive prior distribution was equivalent or superior to Bayesian autologistic regression in terms of predicting to un-sampled areas when strip adaptive cluster sampling was used to survey B. inermis. However, inferences about the relationships between B. inermis presence and environmental predictors differed between the two spatial binary models. The strip adaptive cluster designs we investigate provided a significant advantage in terms of Markov chain Monte Carlo chain convergence when trying to model a sparsely distributed species across a large area. In general, there was little difference in the choice of neighborhood, although the adaptive king was preferred when transects were randomly placed throughout the spatial domain.

  1. Remote sensing of species invasion

    NASA Astrophysics Data System (ADS)

    Clinton, Nicholas Etienne

    The invasion of the Western United States of America by Bromus tectorum, also known as "cheatgrass" is mapped using techniques of remote sensing. Landsat 5 Thematic Mapper (TM) data was radiometrically processed to ground reflectance using the MODTRAN4 atmospheric simulation model. The results of the radiometric processing were checked against ground reflectances with a portable ASD spectrometer. Landsat TM imagery covering portions of Utah State, USA were obtained at two times for each scene, one in the spring and one in the summer. The imagery was radiometrically processed to ground reflectance. Field data on cheatgrass abundance were collected at the same time period of the Landsat imagery. A variety of regression models were tested for predicting cheatgrass abundance. Prediction variables included the extracted ground reflectance from the multi-temporal imagery and ancillary topographic data. A meta-prediction framework was devised for compositing the results of an ensemble of regression models. Using cross-validation, the method was found to predict cheatgrass abundance (as percent) with approximately 15% Root Mean Square Error. The Landsat based prediction maps were used to scale reference data to 250 meter resolution, for prediction over larger spatial areas using the MODerate resolution Imaging Spectro-radiometer (MODIS). MODIS Normalized Difference Vegetation Index (NDVI) maps, at 250 meter spatial resolution and bi-monthly data frequency, were assembled over a five year time period spanning 2001-2005. PRISM monthly total precipitation data, a spatially interpolated (4 kilometer) resolution data product, were compiled over the same time period and the same spatial coverage as the MODIS data. Thin plate (Duchon) splines were fit to the time series of precipitation data and MODIS NDVI in order to generate time series of precipitation and NDVI (with an arbitrary number of data points) over the study area. Metrics designed to quantify ecosystem response to

  2. [Evaluation of the seed stock and dynamics of ripgut brome (Bromus rigidus Roth) in the cultivation of wheat in the Sais area of Morocco].

    PubMed

    Hamal, A; Rzozi, S B; Benbella, M; Msatef, Y; Bouhache, M

    2001-01-01

    The study was conducted on experimental plots differing in cultivation treatment (deep or shallow) at the National School of Agricultural station for three years. The objective was to study the influence of the tillage practices on vertical distribution of the seeds of ripgut brome (Bromus rigidus Roth) in the soil profile. Four tillage methods were tested: Zero tillage (SD), disc plough (PDL) and a disc harrow at two depths, 20 cm (CDM) and 30 cm (CDP). The results show that the type of cultivation affected the distribution of the seeds of ripgut brome. Shallow plots were highly infested by Bromus rigidus (876 plant/m2). The total number of seeds of ripgut brome was 96 and 45% in 0-4 cm of the soil, 3 and 29% in 4-15 cm and 1 and 26% in 15-30 cm, respectively of the deep (CDP) and shallow soil (SD). Deep tillage reduced the seed bank of ripgut brome by 96.6% and 66.7% for shallow. Seeds of ripgut brome survive more than three years at the deep soil. Processes of germination of this weed became functional after 98 days in the soil. The disc plough reduced significantly the brome population and seed bank compared to other tillage methods. PMID:12425100

  3. Drought tolerance in two perennial bunchgrasses used for restoration in the Intermountain West, U.S.A.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The success of Bromus tectorum L., an invasive winter annual grass of North America's Intermountain West, has been attributed to its early germination, superior cold-temperature growth, profuse root production, and high specific leaf area (SLA). To better understand B. tectorum's success with respe...

  4. Genotype-specific responses of Bromus erectus to elevated CO{sub 2} at different levels of biodiversity and endophyte infection - a field experiment

    SciTech Connect

    Steinger, T.; Groppe, K.; Schmid, B. |

    1995-06-01

    In 1994 we initiated a long-term field experiment in a calcareous grassland to study the effects of elevated CO{sub 2} on individuals, populations, and communities. Clonal replicates of 54 genotypes of the dominant grass Bromus erectus were grown in communities planted at three levels of biodiversity (5-, 12-, 31-species plots) and exposed to ambient and elevated CO{sub 2}. The same genotypes were also individually grown in tubes within the field plots. Some genotypes were infected by the endophytic fungus Epichloee typhina. Elevated CO{sub 2} had no significant effects on plant growth, however, there was large variation among genotypes in all measured characters. A significant CO{sub 2}-by-genotype interaction was found for leaf length in the competition-free tubes. Infection by the endophyte led to the abortion of all inflorescences but increased vegetative growth, especially under competitive conditions.

  5. A common-garden study of resource-island effects on a native and an exotic, annual grass after fire

    USGS Publications Warehouse

    Hoover, Amber N.; Germino, Matthew J.

    2012-01-01

    Plant-soil variation related to perennial-plant resource islands (coppices) interspersed with relatively bare interspaces is a major source of heterogeneity in desert rangelands. Our objective was to determine how native and exotic grasses vary on coppice mounds and interspaces (microsites) in unburned and burned sites and underlying factors that contribute to the variation in sagebrush-steppe rangelands of the Idaho National Lab, where interspaces typically have abiotic crusts. We asked how the exotic cheatgrass (Bromus tectorum L.) and native bluebunch wheatgrass (Pseudoroegneria spicata [Pursh] A. Löve) were distributed among the microsites and measured their abundances in three replicate wildfires and nearby unburned areas. We conducted a common-garden study in which soil cores from each burned microsite type were planted with seed of either species to determine microsite effects on establishment and growth of native and exotic grasses. We assessed soil physical properties in the common-garden study to determine the intrinsic properties of each microsite surface and the retention of microsite soil differences following transfer of soils to the garden, to plant growth, and to wetting/drying cycles. In the field study, only bluebunch wheatgrass density was greater on coppice mounds than interspaces, in both unburned and burned areas. In the common-garden experiment, there were microsite differences in soil physical properties, particularly in crust hardness and its relationship to moisture, but soil properties were unaffected by plant growth. Also in the experiment, both species had equal densities yet greater dry mass production on coppice-mound soils compared to interspace soils, suggesting microsite differences in growth but not establishment (likely related to crust weakening resulting from watering). Coppice-interspace patterning and specifically native-herb recovery on coppices is likely important for postfire resistance of this rangeland to cheatgrass.

  6. Landscape characteristics of disturbed shrubsteppe habitats in southwestern Idaho (USA)

    USGS Publications Warehouse

    Knick, Steven T.; Rotenberry, J.T.

    1997-01-01

    We compared 5 zones in shrubsteppe habitats of southwestern Idaho to determine the effect of differing disturbance combinations on landscapes that once shared historically similar disturbance regimes. The primary consequence of agriculture, wildfires, and extensive fires ignited by the military during training activities was loss of native shrubs from the landscape. Agriculture created large square blocks on the landscape, and the landscape contained fewer small patches and more large shrub patches than non-agricultural areas. In contrast, fires left a more fragmented landscape. Repeated fires did not change the distribution of patch sizes, but decreased the total area of remaining shrublands and increased the distance between remaining shrub patches that provide seed sources. Military training with tracked vehicles was associated with a landscape characterized by small, closely spaced, shrub patches. Our results support the general model hypothesized for conversion of shrublands to annual grasslands by disturbance. Larger shrub patches in our region, historically resistant to fire spread and large-scale fires because of a perennial bunchgrass understory, were more fragmented than small patches. Presence of cheatgrass (Bromus tectorum), an exotic annual, was positively related to landscape patchiness and negatively related to number of shrub cells. Thus, cheatgrass dominance can contribute to further fragmentation and loss of the shrub patch by facilitating spread of subsequent fires, carried by continuous fuels, through the patch. The synergistic processes of fragmentation of shrub patches by disturbance, invasion and subsequent dominance by exotic annuals, and fire are converting shrubsteppe in southwestern Idaho to a new state dominated by exotic annual grasslands and high fire frequencies.

  7. Region-wide ecological responses of arid Wyoming big sagebrush communities to fuel treatments

    USGS Publications Warehouse

    Pyke, David A.; Shaff, Scott E.; Lindgren, Andrew I.; Schupp, Eugene W.; Doescher, Paul S.; Chambers, Jeanne C.; Burnham, Jeffrey S.; Huso, Manuela M.

    2014-01-01

    If arid sagebrush ecosystems lack resilience to disturbances or resistance to annual invasives, then alternative successional states dominated by annual invasives, especially cheatgrass (Bromus tectorum L.), are likely after fuel treatments. We identified six Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis Beetle & Young) locations (152–381 mm precipitation) that we believed had sufficient resilience and resistance for recovery. We examined impacts of woody fuel reduction (fire, mowing, the herbicide tebuthiuron, and untreated controls, all with and without the herbicide imazapic) on short-term dominance of plant groups and on important land health parameters with the use of analysis of variance (ANOVA). Fire and mowing reduced woody biomass at least 85% for 3 yr, but herbaceous fuels were reduced only by fire (72%) and only in the first year. Herbaceous fuels produced at least 36% more biomass with mowing than untreated areas during posttreatment years. Imazapic only reduced herbaceous biomass after fires (34%). Tebuthiuron never affected herbaceous biomass. Perennial tall grass cover was reduced by 59% relative to untreated controls in the first year after fire, but it recovered by the second year. Cover of all remaining herbaceous groups was not changed by woody fuel treatments. Only imazapic reduced significantly herbaceous cover. Cheatgrass cover was reduced at least 63% with imazapic for 3 yr. Imazapic reduced annual forb cover by at least 45%, and unexpectedly, perennial grass cover by 49% (combination of tall grasses and Sandberg bluegrass [Poa secunda J. Presl.]). Fire reduced density of Sandberg bluegrass between 40% and 58%, decreased lichen and moss cover between 69% and 80%, and consequently increased bare ground between 21% and 34% and proportion of gaps among perennial plants > 2 m (at least 28% during the 3 yr). Fire, mowing, and imazapic may be effective in reducing fuels for 3 yr, but each has potentially undesirable consequences

  8. Severe plant invasions can increase mycorrhizal fungal abundance and diversity

    PubMed Central

    Lekberg, Ylva; Gibbons, Sean M; Rosendahl, Søren; Ramsey, Philip W

    2013-01-01

    Invasions by non-native plants can alter ecosystem functions and reduce native plant diversity, but relatively little is known about their effect on belowground microbial communities. We show that invasions by knapweed (Centaurea stoebe) and leafy spurge (Euphorbia esula, hereafter spurge)—but not cheatgrass (Bromus tectorum)—support a higher abundance and diversity of symbiotic arbuscular mycorrhizal fungi (AMF) than multi-species native plant communities. The higher AMF richness associated with knapweed and spurge is unlikely due to a co-invasion by AMF, because a separate sampling showed that individual native forbs hosted a similar AMF abundance and richness as exotic forbs. Native grasses associated with fewer AMF taxa, which could explain the reduced AMF richness in native, grass-dominated communities. The three invasive plant species harbored distinct AMF communities, and analyses of co-occurring native and invasive plants indicate that differences were partly driven by the invasive plants and were not the result of pre-invasion conditions. Our results suggest that invasions by mycotrophic plants that replace poorer hosts can increase AMF abundance and richness. The high AMF richness in monodominant plant invasions also indicates that the proposed positive relationship between above and belowground diversity is not always strong. Finally, the disparate responses among exotic plants and consistent results between grasses and forbs suggest that AMF respond more to plant functional group than plant provenance. PMID:23486251

  9. Ecological perspectives of land use history: The Arid Lands Ecology (ALE) Reserve

    SciTech Connect

    Hinds, N R; Rogers, L E

    1991-07-01

    The objective of this study was to gather information on the land use history of the Arid Land Ecology (ALE) Reserve so that current ecological research could be placed within a historical perspective. The data were gathered in the early 1980s by interviewing former users of the land and from previously published research (where available). Interviews with former land users of the ALE Reserve in Benton County, Washington, revealed that major land uses from 1880 to 1940 were homesteading, grazing, oil/gas production, and road building. Land use practices associated with grazing and homesteading have left the greatest impact on the landscape. Disturbed sites where succession is characterized by non-native species, plots where sagebrush was railed away, and sheep trails are major indications today of past land uses. Recent estimates of annual bunchgrass production do ALE do not support the widespread belief that bunchgrass were more productive during the homesteading era, though the invasion of cheatgrass (Bromus tectorum), Jim Hill mustard (Sisymbrium altissium), and other European alien plant species has altered pre-settlement succession patterns. 15 refs., 6 figs., 1 tab.

  10. Avian response to wildfire in interior Columbia basin shrubsteppe

    USGS Publications Warehouse

    Earnst, S.L.; Newsome, H.L.; LaFramboise, W.L.; LaFramboise, N.

    2009-01-01

    Wildfire and conversion of sagebrush (Artemisia spp.) shrublands to cheatgrass (Bromus tectorum) grasslands is a serious threat to the shrubsteppe ecosystem, but few studies have documented wildfire's effects on birds with multiple years of pre- and post-fire data. Using data from avian point counts recorded 4 years before and 7 years after a large-scale, severe wildfire in the Columbia Basin of south-central Washington, we found significant effects of fire on population trends or mean abundance of nearly all species investigated. The Sage Sparrow (Amphispiza belli), a sagebrush obligate, was decreasing at a high rate both pre- and post-fire. Among species inhabiting more open shrubsteppe or grasslands, the mean abundance of three (Grasshopper Sparrow, Ammodramus savannarum; Western Meadowlark, Sturnella neglecta; Vesper Sparrow, Pooecetes gramineus) was lower post-fire and one (Lark Sparrow, Chondestes grammacus) showed an initial, but short-lived, increase post-fire before dropping below pre-fire levels. Only one (Horned Lark, Eremophila alpestris) increased steadily post-fire and had higher post-fire mean abundance. ?? 2009 by The Cooper Ornithological Society. All rights reserved.

  11. Interaction Assessment: A modeling tool for predicting population dynamics from field data

    USGS Publications Warehouse

    Emlen, John M.; Duda, Jeffrey J.; Kirchhoff, Matt D.; Freeman, D. Carl

    2006-01-01

    Interaction Assessment (INTASS) is a field and analytic methodology for constructing population dynamics models. Because data collected in generating a model for one species comprise much of the information needed for other species, a small increase in effort can result in simultaneous expressions for the dynamics of multiple species. These expressions can be used to simulate whole community responses to environmental change, including management actions. Since publication of the most recent paper in this series, the INTASS methodology has undergone a large number of developments. These include the use of conceptual models to direct field and modeling efforts and incorporation of an information theoretic approach to model selection. We review these modifications and additions, applying them to a population of Sitka black-tailed deer (Odocoilius hemionis) in Alaska and to cheatgrass (Bromus tectorum) at the Desert Experimental Range in Utah. In both cases, useful information about the species’ ecology and population trends was ascertained. INTASS is portable across a wide range of taxa, habitats and management situations.

  12. Regional climate model downscaling may improve the prediction of alien plant species distributions

    NASA Astrophysics Data System (ADS)

    Liu, Shuyan; Liang, Xin-Zhong; Gao, Wei; Stohlgren, Thomas J.

    2014-12-01

    Distributions of invasive species are commonly predicted with species distribution models that build upon the statistical relationships between observed species presence data and climate data. We used field observations, climate station data, and Maximum Entropy species distribution models for 13 invasive plant species in the United States, and then compared the models with inputs from a General Circulation Model (hereafter GCM-based models) and a downscaled Regional Climate Model (hereafter, RCM-based models).We also compared species distributions based on either GCM-based or RCM-based models for the present (1990-1999) to the future (2046-2055). RCM-based species distribution models replicated observed distributions remarkably better than GCM-based models for all invasive species under the current climate. This was shown for the presence locations of the species, and by using four common statistical metrics to compare modeled distributions. For two widespread invasive taxa ( Bromus tectorum or cheatgrass, and Tamarix spp. or tamarisk), GCM-based models failed miserably to reproduce observed species distributions. In contrast, RCM-based species distribution models closely matched observations. Future species distributions may be significantly affected by using GCM-based inputs. Because invasive plants species often show high resilience and low rates of local extinction, RCM-based species distribution models may perform better than GCM-based species distribution models for planning containment programs for invasive species.

  13. Evaportranspiration studies for protective barriers: FY 1989 status report

    SciTech Connect

    Link, S.O.; Thiede, M.E.; Downs, J.L.; Lettau, D.J. ); Waugh, W.J. )

    1992-05-01

    This document describes the results of technological developments and experiments at the Small Tube Lysimeter Facility. The objective of this research is to develop the capability to predict evapotranspiration in support of studies of water infiltration control for the Hanford Protective Barrier Development Program. Evapotranspiration is the combined loss of water from plants and soil surfaces to the atmosphere. This process must be predictable to adequately model soil water dynamics. We develop a miniature greenhouse (gas exchange chamber), where internal temperature and relative humidity can be controlled. With this device we measured evapotranspiration, transpiration, and carbon dioxide exchange rates from lysimeters with various surface and plant characteristics. We tested the effect on gas exchange rates and sand, gravel, admix, and soil surfaces in lysimeters where, cheat-grass, Bromus tectorum, had been seeded. Results showed that evapotranspiration was unaffected by the surface treatments. Estimated transpiration rates were higher for plants growing in sand compared with rates for plants growing in the admix and soil treatments. Soil evaporation rates were higher in the gravel treatment than in the sand treatment. Future research will entail parameterization of relationships between evapotranspiration, transpiration, soil evaporation, carbon dioxide exchange, and the abiotic and biotic factors that drive these processes for model development.

  14. Cascading effects of fire retardant on plant-microbe interactions, community composition, and invasion.

    PubMed

    Marshall, Abigail; Waller, Lauren; Lekberg, Ylva

    2016-06-01

    Climate change, historical fire suppression, and a rise in human movements in urban-forest boundaries have resulted in an increased use of long-term fire retardant (LTFR). While LTFR is an effective fire-fighting tool, it contains high concentrations of nitrogen and phosphorus, and little is known about how this nutrient pulse affects terrestrial ecosystems. We used field surveys and greenhouse experiments to quantify effects of LTFR on plant productivity, community composition, and plant interactions with the ubiquitous root symbiont arbuscular mycorrhizal fungi (AMF). In the field, LTFR applications were associated with persistent shifts in plant communities toward exotic annuals with little or no dependency of AMF. Plants exposed to LTFR were less colonized by AMF, both in field surveys and in the greenhouse, and this was most likely due to the substantial and persistent increase in soil available phosphorus. All plants grew bigger with LTFR in the greenhouse, but the invasive annual cheatgrass (Bromus tectorum) benefitted most. While LTFR can control fires, it may cause long-term changes in soil nutrient availabilities, disrupt plant interactions with beneficial soil microbes, and exasperate invasion by some exotic plants. PMID:27509743

  15. Physical, Chemical, Ecological, and Age Data and Trench Logs from Surficial Deposits at Hatch Point, Southeastern Utah

    USGS Publications Warehouse

    Goldstein, Harland L.; Miller, Mark E.; Yount, James C.; Reheis, Marith C.; Reynolds, Richard L.; Belnap, Jayne; Lamothe, Paul J.; McGeehan, John P.

    2009-01-01

    This report presents data and describes the methodology for physical, chemical and ecological measurements of sediment, soil, and vegetation, as well as age determinations of surficial deposits at Hatch Point, Canyon Rims area, Colorado Plateau, southeastern Utah. The results presented in this report support a study that examines geomorphic and soil factors that may influence boundaries between shrubland and grassland ecosystems in the study area. Shrubland ecosystems dominated by sagebrush (Artemisia tridentata) and grassland ecosystems dominated by native perennial grasses (for example, Hilaria jamesii and Sporabolis sp.) are high-priority conservation targets for the Federal Bureau of Land Management (BLM) and other resource managers because of their diversity, productivity, and vital importance as wildlife habitat. These ecosystems have been recognized as imperiled on a regional scale since at least the mid-1990s due to habitat loss (type conversions), land-use practices, and invasive exotic plants. In the Intermountain West, the exotic annual cheatgrass (Bromus tectorum) is recognized as one of the most pervasive and serious threats to the health of native sagebrush and grassland ecosystems through effects on fire regimes and resource conditions experienced by native species.

  16. Sagebrush Ecosystems Under Fire

    SciTech Connect

    Downs, Janelle L.

    2014-12-30

    Since settlement of the western United States began, sagebrush (Artemisia L. spp.) ecosystems have decreased both in quantity and quality. Originally encompassing up to 150 million acres in the West, the “interminable fields” of sage described by early explorers (Fremont 1845) have been degraded and often eliminated by conversion to agriculture, urbanization, livestock grazing, invasion by alien plants, and alteration of wildfire cycles (Hann et al. 1997; West 1999). More than half of the original sagebrush steppe ecosystems in Washington have been converted to agriculture and many of the remaining stands of sagebrush are degraded by invasion of exotic annuals such as cheatgrass (Bromus tectorum L.). Today, sagebrush ecosystems are considered to be one of the most imperiled in the United States (Noss, LeRoe and Scott 1995), and more than 350 sagebrush-associated plants and animals have been identified as species of conservation concern (Suring et al. 2005; Wisdom et al. 2005). The increasing frequency of wildfire in sagebrush-dominated landscapes is one of the greatest threats to these habitats and also presents one of the most difficult to control.

  17. Mechanisms Controlling Species Responses to Climate Change: Thermal Tolerances and Shifting Range Limits. (Invited)

    NASA Astrophysics Data System (ADS)

    Sage, R. F.; Bykova, O.; Coiner, H.

    2010-12-01

    One of the main effects of anthropogenic climate change will be widespread shifts in species distribution, with the common assumption that they will migrate to higher elevation and latitude. While this assumption is supported by migration patterns following climate warming in the past 20,000 years, it has not been rigorously evaluated in terms of physiological mechanism, despite the implication that migration in response to climate warming is controlled by some form of thermal adaptation. We have been evaluating the degree to which species range limits are controlled by physiological patterns of thermal tolerance in bioinvaders of North America. Bioinvaders presumably have few biotic controls over their distribution and thus are more likely to fully exploit their thermal niche. In cheatgrass (Bromus tectorum), the minimum lethal temperature in winter is -32C, which corresponds to the mean winter minimum temperature at its northern range limit. In red brome (Bromus rubens), the minimum lethal temperature is also near -32C, which is well below the minimum winter temperature near -20C that corresponds to its northern distribution limit. In kudzu (Pueraria lobata), the minimum lethal temperature is near -20C, which corresponds to the midwinter minimum at its northern distribution limit; however, overwintering kudzu tissues are insulated by soil and snow cover, and thus do not experience lethal temperatures at kudzu's northern range limit. These results demonstrate that some invasive species can exploit the potential range defined by their low temperature tolerance and thus can be predicted by mechanistic models to migrate to higher latitudes with moderation of winter cold. The distribution of other invaders such as kudzu and red brome are not controlled by tolerance of midwinter cold. Developing mechanistic models of their distributions, and how these might change with climate warming, will require extensive physiological study.

  18. Seasonal and spatial patterns of metals at a restored copper mine site II. Copper in riparian soils and Bromus carinatus shoots.

    PubMed

    Silk, Wendy K; Bambic, Dustin G; O'Dell, Ryan E; Green, Peter G

    2006-12-01

    Soil and plants were sampled throughout winter and spring near a perennial stream traversing a restored mine site in a winter-rainy climate. Within 1m of an acidic reach of the stream, soil had pH 3-5 and 50-100 microg/g "bioavailable" copper (extractable with 0.01 M CaCl2). Soil 2-3 m from the stream had pH 5-8 and lower (less than 3 microg/g) bioavailable copper. "Oxide-bound" copper (extractable with 2N HCl) was 50-100 microg/g at most locations. Copper concentrations in the shoots of field-collected Bromus carinatus declined from 20 microg/g in winter to 2 microg/g in spring at all sampling sites. A similar temporal pattern was found in plants grown under controlled conditions. Thus B. carinatus has a developmental program for control of shoot copper concentration, causing a seasonally-varying pattern of copper phytoaccumulation over a large range of copper availability in the soil. PMID:16631289

  19. Compost amendment of Cu-Zn minespoil reduces toxic bioavailable heavy metal concentrations and promotes establishment and biomass production of Bromus carinatus (Hook and Arn.).

    PubMed

    O'Dell, Ryan; Silk, Wendy; Green, Peter; Claassen, Victor

    2007-07-01

    A series of lab and greenhouse studies were undertaken to understand how Cu and Zn toxicity influences Bromus carinatus (Hook and Arn.) growth, to what degree an organic amendment (yard waste compost) may reduce Cu and Zn bioavailability in Cu-Zn minespoil and promote plant growth in combination with fertilizer, and how the vertical distribution of compost in the minespoil influences rooting depth. Root Cu and Zn toxicity thresholds were determined to be 1 mgL(-1) and 10 mgL(-1) in solution, respectively. The compost amendment had exceptionally high Cu and Zn binding capacities (0.17 and 0.08 g metal g C(-1), for Cu and Zn, respectively) that were attributed to high compost humic and fulvic acid concentrations. Maximum plant biomass was achieved when minespoil was amended with compost and fertilizer in combination. Fertilizer alone had no effect on plant growth. Mixing compost into the minespoil was essential to promote adequate rooting depth. PMID:17240016

  20. Vegetation Response to Western Juniper Slash Treatments

    NASA Astrophysics Data System (ADS)

    O'Connor, Casey; Miller, Rick; Bates, Jonathan D.

    2013-09-01

    The expansion of piñon-juniper woodlands the past 100 years in the western United States has resulted in large scale efforts to kill trees and recover sagebrush steppe rangelands. It is important to evaluate vegetation recovery following woodland control to develop best management practices. In this study, we compared two fuel reduction treatments and a cut-and-leave (CUT) treatment used to control western juniper ( Juniperus occidentalis spp. occidentalis Hook.) of the northwestern United States. Treatments were; CUT, cut-and-broadcast burn (BURN), and cut-pile-and-burn the pile (PILE). A randomized complete block design was used with five replicates of each treatment located in a curl leaf mahogany ( Cercocarpus ledifolius Nutt. ex Torr. & A. Gray)/mountain big sagebrush ( Artemisia tridentata Nutt. spp. vaseyana (Rydb.) Beetle)/Idaho fescue ( Festuca idahoensis Elmer) association. In 2010, 4 years after tree control the cover of perennial grasses (PG) [Sandberg's bluegrass ( Poa secunda J. Pres) and large bunchgrasses] were about 4 and 5 % less, respectively, in the BURN (7.1 ± 0.6 %) than the PILE (11.4 ± 2.3 %) and CUT (12.4 ± 1.7 %) treatments ( P < 0.0015). In 2010, cover of invasive cheatgrass ( Bromus tectorum L.) was greater in the BURN (6.3 ± 1.0 %) and was 50 and 100 % greater than PILE and CUT treatments, respectively. However, the increase in perennial bunchgrass density and cover, despite cheatgrass in the BURN treatment, mean it unlikely that cheatgrass will persist as a major understory component. In the CUT treatment mahogany cover increased 12.5 % and density increased in from 172 ± 25 to 404 ± 123 trees/ha. Burning, killed most or all of the adult mahogany, and mahogany recovery consisted of 100 and 67 % seedlings in the PILE and BURN treatments, respectively. After treatment, juniper presence from untreated small trees (<1 m tall; PILE and CUT treatments) and seedling emergence (all treatments) represented 25-33 % of pre-treatment tree

  1. Vegetation response to western juniper slash treatments.

    PubMed

    O'Connor, Casey; Miller, Rick; Bates, Jonathan D

    2013-09-01

    The expansion of piñon-juniper woodlands the past 100 years in the western United States has resulted in large scale efforts to kill trees and recover sagebrush steppe rangelands. It is important to evaluate vegetation recovery following woodland control to develop best management practices. In this study, we compared two fuel reduction treatments and a cut-and-leave (CUT) treatment used to control western juniper (Juniperus occidentalis spp. occidentalis Hook.) of the northwestern United States. Treatments were; CUT, cut-and-broadcast burn (BURN), and cut-pile-and-burn the pile (PILE). A randomized complete block design was used with five replicates of each treatment located in a curl leaf mahogany (Cercocarpus ledifolius Nutt. ex Torr. & A. Gray)/mountain big sagebrush (Artemisia tridentata Nutt. spp. vaseyana (Rydb.) Beetle)/Idaho fescue (Festuca idahoensis Elmer) association. In 2010, 4 years after tree control the cover of perennial grasses (PG) [Sandberg's bluegrass (Poa secunda J. Pres) and large bunchgrasses] were about 4 and 5 % less, respectively, in the BURN (7.1 ± 0.6 %) than the PILE (11.4 ± 2.3 %) and CUT (12.4 ± 1.7 %) treatments (P < 0.0015). In 2010, cover of invasive cheatgrass (Bromus tectorum L.) was greater in the BURN (6.3 ± 1.0 %) and was 50 and 100 % greater than PILE and CUT treatments, respectively. However, the increase in perennial bunchgrass density and cover, despite cheatgrass in the BURN treatment, mean it unlikely that cheatgrass will persist as a major understory component. In the CUT treatment mahogany cover increased 12.5 % and density increased in from 172 ± 25 to 404 ± 123 trees/ha. Burning, killed most or all of the adult mahogany, and mahogany recovery consisted of 100 and 67 % seedlings in the PILE and BURN treatments, respectively. After treatment, juniper presence from untreated small trees (<1 m tall; PILE and CUT treatments) and seedling emergence (all treatments) represented 25-33 % of

  2. Impact of grazing intensity during drought in an Arizona grassland.

    PubMed

    Loeser, Matthew R R; Sisk, Thomas D; Crews, Timothy E

    2007-02-01

    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 surveys of modified Whittaker plots for 8 years and examined plant composition shifts among treatments and years. High-impact grazing had strong directional effects that led to a decline in perennial forb cover and an increase in annual plants, particularly the exotic cheatgrass (Bromus tectorum L.). A twofold increase in plant cover by exotic species followed a severe drought in the sixth year of the study, and this increase was greatest in the high-impact grazing plots, where native cover declined by one-half. Cattle removal resulted in little increase in native plant cover and reduced plant species richness relative to the moderate grazing control. Our results suggest that some intermediate level of cattle grazing may maintain greater levels of native plant diversity than the alternatives of cattle removal or high-density, short-duration grazing practices. Furthermore, episodic drought interacts with cattle grazing, leading to infrequent, but biologically important shifts in plant communities. Our results demonstrate the importance of climatic variation in determining ecological effects of grazing practices, and we recommend improving conservation efforts in arid rangelands by developing management plans that anticipate this variation. PMID:17298514

  3. Diets and habitat analyses of mule deer on the 200 areas of the Hanford Site in southcentral Washington

    SciTech Connect

    Uresk, D.W.; Uresk, V.A.

    1980-10-01

    Forty-four food items were identified in the fecal pellets of the mule deer (Odocoileus hemionus hemionus) on three areas of the Hanford Site. Microscopic analysis of plant fragments indicated that bitterbrush was the most common species occurring in the diets of deer from the B-C Cribs area. Russian thistle (Salsola kali) and goldenrod (Solidago sp.) were the most abundant plants found in the fecal pellets collected from B Pond and Gable Mountain Pond habitats, respectively. The similarity in diets among the habitats was low, ranging from 10% to 16%. Preference indices of forage plants among sites were not similar (7% to 19%). The B-C Cribs, B Pond and Gable Mountain Pond habitats were characterized for canopy cover and frequency of occurrence of plant species. Twelve species were sampled in the B-C Cribs and B Pond areas; 22 species were identified on the Gable Mountain site. The most commonly occurring plant was cheatgrass (Bromus tectorum) in all three sites. The similarity in frequency and canopy cover of plants was low among sites. Mule deer inhabiting the Hanford site can serve as a pathway for movement of radioactive material from low-level radioactive waste management areas to man. Maximum levels of /sup 137/Cs found in deer pellet groups collected from B Pond and Gable Mountain Pond areas were 100 pCi/g and 128 pCi/g, respectively. Background levels were reported at B-C Cribs area. Maximum /sup 90/Sr values found in deer pellets at B Pond were 107 pCi/g and 184 pCi/g at Gable Mountain Pond.

  4. Use of Terrestrial Laser Scanning to Model Fuel Characteristics in Shrub-Steppe

    NASA Astrophysics Data System (ADS)

    Anderson, K.; Glenn, N. F.

    2013-12-01

    Biological invasion, climate change, and other anthropogenic and non-anthropogenic factors are altering ecosystem function of arid shrublands in the western U.S., with notable effects including changes in community composition and increased incidence and severity of wildfires. Wildfire itself contributes to replacement of native flora communities with fire-prone invasives (prominently cheatgrass, Bromus tectorum), a positive feedback loop which threatens long-term degradation of burned areas. Efficient methods of vegetation inventory over large areas are essential to study and manage changes in ecological paradigms, and furthermore to anticipate and control wildfire. However, the application of remote sensing information from aerial or satellite platforms to shrub-steppe ecosystems is limited by spectral signal mixing and coarseness of data relative to low-stature vegetation. Terrestrial laser scanning (TLS) technology provides rapid collection of high-resolution structural information at ranges up to hundreds of meters, offering an opportunity to efficiently record vegetation characteristics in large swaths. We tested the ability of TLS to quantify abundance and biomass of different vegetation stem diameter classes in shrub-steppe plots in southwestern Idaho, with classes selected to emulate timelag fuel classes commonly used in fuel inventories and fire modeling. We used data from destructively-sampled reference quadrats within scans for training and evaluation of TLS-derived estimates. We demonstrate TLS as an effective standalone tool for shrubland vegetation inventory, while future applications of these methods include collecting training data for interpretation of coarser remote sensing information, and providing accurate 3D simulations of fuel beds to spatially explicit wildfire models.

  5. A spatial model to prioritize sagebrush landscapes in the intermountain west (U.S.A.) for restoration

    USGS Publications Warehouse

    Meinke, C.W.; Knick, S.T.; Pyke, D.A.

    2009-01-01

    The ecological integrity of Sagebrush (Artemisia spp.) ecosystems in the Intermountain West (U.S.A.) has been diminished by synergistic relationships among human activities, spread of invasive plants, and altered disturbance regimes. An aggressive effort to restore Sagebrush habitats is necessary if we are to stabilize or improve current habitat trajectories and reverse declining population trends of dependent wildlife. Existing economic resources, technical impediments, and logistic difficulties limit our efforts to a fraction of the extensive area undergoing fragmentation, degradation, and loss. We prioritized landscapes for restoring Sagebrush habitats within the intermountain western region of the United States using geographic information system (GIS) modeling techniques to identify areas meeting a set of conditions based on (1) optimum abiotic and biotic conditions favorable for revegetation of Sagebrush; (2) potential to increase connectivity of Sagebrush habitats in the landscape to benefit wildlife; (3) location of population strongholds for Greater Sage-Grouse (Centrocercus urophasianus, a species of conservation concern); and (4) potential impediments to successful restoration created by Cheatgrass (Bromus tectorum, an invasive exotic annual grass). Approximately 5.8 million ha in southwestern Idaho, northern Nevada, and eastern Oregon met our criteria for restoring Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis) and 5.1 million ha had high priority for restoring Mountain big sagebrush (A. tridentata ssp. vaseyana). Our results represent an integral component in a hierarchical framework after which site-specific locations for treatments can be focused within high-priority areas. Using this approach, long-term restoration strategies can be implemented that combine local-scale treatments and objectives with large-scale ecological processes and priorities. ?? 2008 Society for Ecological Restoration International.

  6. Resilience and resistance of sagebrush ecosystems: implications for state and transition models and management treatments

    USGS Publications Warehouse

    Chambers, Jeanne C.; Miller, Richard F.; Board, David I.; Pyke, David A.; Roundy, Bruce A.; Grace, James B.; Schupp, Eugene W.; Tausch, Robin J.

    2014-01-01

    In sagebrush ecosystems invasion of annual exotics and expansion of piñon (Pinus monophylla Torr. and Frem.) and juniper (Juniperus occidentalis Hook., J. osteosperma [Torr.] Little) are altering fire regimes and resulting in large-scale ecosystem transformations. Management treatments aim to increase resilience to disturbance and enhance resistance to invasive species by reducing woody fuels and increasing native perennial herbaceous species. We used Sagebrush Steppe Treatment Evaluation Project data to test predictions on effects of fire vs. mechanical treatments on resilience and resistance for three site types exhibiting cheatgrass (Bromus tectorum L.) invasion and/or piñon and juniper expansion: 1) warm and dry Wyoming big sagebrush (WY shrub); 2) warm and moist Wyoming big sagebrush (WY PJ); and 3) cool and moist mountain big sagebrush (Mtn PJ). Warm and dry (mesic/aridic) WY shrub sites had lower resilience to fire (less shrub recruitment and native perennial herbaceous response) than cooler and moister (frigid/xeric) WY PJ and Mtn PJ sites. Warm (mesic) WY Shrub and WY PJ sites had lower resistance to annual exotics than cool (frigid to cool frigid) Mtn PJ sites. In WY shrub, fire and sagebrush mowing had similar effects on shrub cover and, thus, on perennial native herbaceous and exotic cover. In WY PJ and Mtn PJ, effects were greater for fire than cut-and-leave treatments and with high tree cover in general because most woody vegetation was removed increasing resources for other functional groups. In WY shrub, about 20% pretreatment perennial native herb cover was necessary to prevent increases in exotics after treatment. Cooler and moister WY PJ and especially Mtn PJ were more resistant to annual exotics, but perennial native herb cover was still required for site recovery. We use our results to develop state and transition models that illustrate how resilience and resistance influence vegetation dynamics and management options.

  7. Soil resources influence vegetation and response to fire and fire-surrogate treatments in sagebrush-steppe ecosystems

    USGS Publications Warehouse

    Rau, Benjamin M.; Chambers, Jeanne C.; Pyke, David A.; Roundy, Bruce A.; Schupp, Eugene W.; Doescher, Paul; Caldwell, Todd G.

    2014-01-01

    Current paradigm suggests that spatial and temporal competition for resources limit an exotic invader, cheatgrass (Bromus tectorum L.), which once established, alters fire regimes and can result in annual grass dominance in sagebrush steppe. Prescribed fire and fire surrogate treatments (mowing, tebuthiuron, and imazapic) are used to reduce woody fuels and increase resistance to exotic annuals, but may alter resource availability and inadvertently favor invasive species. We used four study sites within the Sagebrush Steppe Treatment Evaluation Project (SageSTEP) to evaluate 1) how vegetation and soil resources were affected by treatment, and 2) how soil resources influenced native herbaceous perennial and exotic annual grass cover before and following treatment. Treatments increased resin exchangeable NH4+, NO3−, H2PO4−, and K+, with the largest increases caused by prescribed fire and prolonged by application of imazapic. Burning with imazapic application also increased the number of wet growing degree days. Tebuthiuron and imazapic reduced exotic annual grass cover, but imazapic also reduced herbaceous perennial cover when used with prescribed fire. Native perennial herbaceous species cover was higher where mean annual precipitation and soil water resources were relatively high. Exotic annual grass cover was higher where resin exchangeable H2PO4− was high and gaps between perennial plants were large. Prescribed fire, mowing, and tebuthiuron were successful at increasing perennial herbaceous cover, but the results were often ephemeral and inconsistent among sites. Locations with sandy soil, low mean annual precipitation, or low soil water holding capacity were more likely to experience increased exotic annual grass cover after treatment, and treatments that result in slow release of resources are needed on these sites. This is one of few studies that correlate abiotic variables to native and exotic species cover across a broad geographic setting, and that

  8. Nest-site selection and reproductive success of greater sage-grouse in a fire-affected habitat of northwestern Nevada

    USGS Publications Warehouse

    Lockyer, Zachary B.; Coates, Peter S.; Casazza, Michael L.; Espinosa, Shawn; Delehanty, David J.

    2015-01-01

    Identifying links between micro-habitat selection and wildlife reproduction is imperative to population persistence and recovery. This information is particularly important for landscape species such as greater sage-grouse (Centrocercus urophasianus; sage-grouse). Although this species has been widely studied, because environmental factors can affect sage-grouse populations, local and regional studies are crucial for developing viable conservation strategies. We studied the habitat-use patterns of 71 radio-marked sage-grouse inhabiting an area affected by wildfire in the Virginia Mountains of northwestern Nevada during 2009–2011 to determine the effect of micro-habitat attributes on reproductive success. We measured standard vegetation parameters at nest and random sites using a multi-scale approach (range = 0.01–15,527 ha). We used an information-theoretic modeling approach to identify environmental factors influencing nest-site selection and survival, and determine whether nest survival was a function of resource selection. Sage-grouse selected micro-sites with greater shrub canopy cover and less cheatgrass (Bromus tectorum) cover than random sites. Total shrub canopy, including sagebrush (Artemisia spp.) and other shrub species, at small spatial scales (0.8 ha and 3.1 ha) was the single contributing selection factor to higher nest survival. These results indicate that reducing the risk of wildfire to maintain important sagebrush habitats could be emphasized in sage-grouse conservation strategies in Nevada. Managers may seek to mitigate the influx of annual grass invasion by preserving large intact sagebrush-dominated stands with a mixture of other shrub species. For this area of Nevada, the results suggest that ≥40% total shrub canopy cover in sage-grouse nesting areas could yield improved reproductive success. 

  9. Phenology of exotic invasive weeds associated with downy brome

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The exotic and highly invasive annual grass downy brome (Bromus tectorum) has invaded millions of hectares of rangelands throughout the Intermountain West. Downy brome increases the chance, rate, season and spread of wildfires, resulting in the destruction of native plant communities and the wildli...

  10. Intraspecific and interspecific pair-wise seedling competition between exotic annual grasses and native perennials: Plant-soil relationships

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Few studies have examined plant-soil relationships in competitive arenas between exotic and native plants in the western United States. A pair-wise competitive design was used to evaluate plant-soil relationships between seedings of the exotic annual grasses Bromus tectorum and Taentherium caput-med...

  11. Returning succession to downy brome dominated rangelands: roadblocks to perennial grass establishment

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The most common cause of successional retrogression in the Great Basin is wildfires fueled by downy brome (Bromus tectorum). Downy brome invasion has reduced fire intervals from an estimated 60-100 years down to 5-10 years. Our previous research found that establishment of long-lived perennial grass...

  12. Population level response of downy brome to soil growing medium

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Downy brome (Bromus tectorum) is the most ubiquitous exotic invasive weed in the Intermountain West. A major issue for management is the extreme generalist plastic nature of downy brome. We hypothesized that soil growing medium would effect all measured response variables representing some degree of...

  13. Adding Fuel to the Fire: The Contribution of Perennial Bunchgrasses in Altering Fire Regimes in the Great Basin

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The historic fire return interval in Wyoming sagebrush ecosystems has been estimated in the hundreds of years; however, the current fire regime has shifted to short fire return intervals with some areas burning six times in the past 60 years. Invasive annual grasses (e.g. Bromus tectorum) are freque...

  14. Large-scale downy brome treatments alter plant-soil relationships and promote perennial grasses in salt desert shrublands

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The interrelationship between invasive annual grass abundance and soil resource availability varies spatially and temporally within ecosystems and may be altered by land treatments. We evaluated these relationships in two salt desert landscapes where the local abundance of Bromus tectorum L. (downy...

  15. Plant nitrogen uptake drives rhizosphere bacterial community assembly during plant growth

    Technology Transfer Automated Retrieval System (TEKTRAN)

    When plant species establish in novel environments, they often modify microbial communities and soil properties in ways that enhance their own success. Upon invasion, the C3 annual grass Bromus tectorum appears to support soil microbial communities that have higher soil nitrogen (N) mineralization r...

  16. The role of plant litter on nutrient mineralization and vegetation dynamics in three sage-steppe communities with differing levels of annual grass invasion

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plant litter is an integral part of ecosystem nutrient cycling, which directly impacts vegetation dynamics. The net effects of litter are largely determined by the quantity and source material of the litter. Invasion of sage-steppe communities by annual grasses (e.g., Bromus tectorum) has caused dra...

  17. Process-based management approaches for salt desert shrublands dominated by downy brome

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Downy brome grass (Bromus tectorum L.) invasion has severely altered key ecological processes such as disturbance regimes, soil nutrient cycling, community assembly, and successional pathways in semi-arid Great Basin salt desert shrublands. Restoring the structure and function of these severly alte...

  18. The importance of education in managing invasive plant species

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Invasive plant species can establish in diverse environments and with the increase in human mobility, they are no longer restricted to isolated pockets in remote parts of the world. Cheat grass (Bromus tectorum L.) in rangelands, purple loosestrife (Lythrum salicaria L.) in wet lands and Canada this...

  19. Downy brome seed ecology: From flower to emergence

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Downy brome (Bromus tectorum) seed is very common in seed banks throughout Great Basin rangelands. Previously, using a soil bioassay method, we tested 100 separate sites within the Great Basin (1000 samples) to measure downy brome seed bank densities. The locations differed greatly by precipitation,...

  20. Trajectories of change in sagebrush steppe vegetation communities in relation to multiple wildfires

    SciTech Connect

    Davies, G. M.; Bakker, J. D.; Dettweiler-Robinson, E.; Dunwiddie, Peter W.; Hall, S. A.; Downs, Janelle L.; Evans, J.

    2012-07-01

    Repeated perturbations, both biotic and abiotic, can lead to fundamental changes in the nature of ecosystems including changes in state. Sagebrush-steppe communities provide important habitat for wildlife and grazing for livestock. Fire is an integral part of these systems, but there is concern that increased ignition frequencies and invasive species are fundamentally altering these systems. Despite these issues, the majority of studies of fire effects in Artemisia tridentata wyomingensis-dominated systems have focused on the effects of single burns. The Arid Lands Ecology Reserve (ALE), in south-central Washington (U.S.A.), was one of the largest areas of continuous shrub-steppe habitat in the state until large wildfires burnt the majority of it in 2000 and 2007. We analysed data from permanent vegetation transects established in 1996 and resampled in 2002 and 2009. Our objective was to describe how the fires, and subsequent post-fire restoration efforts, affected communities successional pathways. Plant communities differed in response to repeated fire and restoration; these differences could largely be ascribed to the functional traits of the dominant species. Low elevation communities, previously dominated by obligate seeders, moved farthest from their initial composition and were dominated by weedy, early successional species in 2009. Higher elevation sites with resprouting shrubs, native bunchgrasses and few invasive species were generally more resilient to the effects of repeated disturbances. Shrub cover has been almost entirely removed from ALE, though there is evidence of recovery where communities were dominated by re-sprouters. Cheatgrass (Bromus tectorum) dominance was reduced by herbicide application in areas where it was previously abundant but increased significantly in untreated areas. Several re-sprouting species, notably Phlox longifolia and Poa secunda, expanded remarkably following competitive release from shrub canopies and/or abundant

  1. Abscisic acid-induced heat tolerance in Bromus inermis Leyss cell-suspension cultures. Heat-stable, abscisic acid-responsive polypeptides in combination with sucrose confer enhanced thermostability.

    PubMed Central

    Robertson, A J; Ishikawa, M; Gusta, L V; MacKenzie, S L

    1994-01-01

    Increased heat tolerance is most often associated with the synthesis of heat-shock proteins following pre-exposure to a nonlethal heat treatment. In this study, a bromegrass (Bromus inermis Leyss cv Manchar) cell suspension cultured in a medium containing 75 microM abscisic acid (ABA) without prior heat treatment had a 87% survival rate, as determined by regrowth analysis, following exposure to 42.5 degrees C for 120 min. In contrast, less than 1% of the control cells survived this heat treatment. The heat tolerance provided by treatment with 75 microM ABA was first evidenced after 4 d of culture and reached a maximum tolerance after 11 d of culture. Preincubation with sucrose partially increased the heat tolerance of control cells and rendered ABA-treated cells tolerant to 45 degrees C for 120 min (a completely lethal heat treatment for control cells). Comparative two-dimensional polyacrylamide gel electrophoresis of cellular protein isolated from heat-tolerant cells identified 43 ABA-responsive proteins of which 26 were heat stable (did not coagulate and remained soluble after 30 min at 90 degrees C). Eight heat-stable, ABA-responsive proteins ranging from 23 to 45 kD had similar N-terminal sequences. The ABA-responsive (43-20 kD), but none of the control heat-stable, proteins cross-reacted to varying degrees with a polyclonal antibody directed against a conserved, lysine-rich dehydrin sequence. A group of 20- to 30-kD heat-stable, ABA-responsive proteins cross-reacted with both the anti-dehydrin antibody and an antibody directed against a cold-responsive winter wheat protein (Wcs 120). In ABA-treated cells, there was a positive correlation between heat- and pH-induced coagulation of a cell-free homogenate and the heat tolerance of these cells. At 50 degrees C, control homogenates coagulated after 8 min, whereas cellular fractions from ABA-treated cells showed only marginal coagulation after 15 min. In protection assays, addition of heat-stable, ABA

  2. Variation in semi-arid soil seed banks

    SciTech Connect

    Boudell-Flanary, J.A.; Link, S.O. |

    1995-09-01

    Seeds recovered from soils in the semi-arid shrub-steppe were compared to test for differences between the seed banks found beneath and cryptogamic crust and the crevices in the crust. Seed quantity found within the crevices was 56% higher than that under the cryptogamic crust. Pseudoroegneria spicata, Poa sandbergii, Bromus tectorum, and Artemisia tridentata are the common species found at the research site. Seeds of Bromus tectorum, Erigeron spp., and Poa spp. were found in the crevices of the crust. Seeds of Artemisia tridentata were not found in the seed banks of either the cryptogamic crust or the crevices in the crust. The higher amount of seeds found in the crevices of the cryptogamic crust suggests that the crevices play a significant role in determining the distributional pattern of shrub-steppe vegetation.

  3. Geomorphic and land cover identification of dust sources in the eastern Great Basin of Utah, U.S.A.

    NASA Astrophysics Data System (ADS)

    Hahnenberger, Maura; Nicoll, Kathleen

    2014-01-01

    This study identifies anthropogenically disturbed areas and barren playa surfaces as the two primary dust source types that repeatedly contribute to dust storm events in the eastern Great Basin of western Utah, U.S.A. This semi-arid desert region is an important contributor to dust production in North America, with this study being the first to specifically identify and characterize regional dust sources. From 2004 to 2010, a total of 51 dust event days (DEDs) affected the air quality in Salt Lake City, UT. MODIS satellite imagery during 16 of these DEDs was analyzed to identify dust plumes, and assess the characteristics of dust source areas. A total of 168 plumes were identified, and showed mobilization of dust from Quaternary deposits located within the Bonneville Basin. This analysis identifies 4 major and 5 secondary source areas for dust in this region, which produce dust primarily during the spring and fall months and during moderate or greater drought conditions, with a Palmer Drought Index (PDI) of - 2 or less. The largest number of observed dust plumes (~ 60% of all plumes) originated from playas (ephemeral lakes) and are classified as barren land cover with a silty clay soil sediment surface. Playa surfaces in this region undergo numerous recurrent anthropogenic disturbances, including military operations and anthropogenic water withdrawal. Anthropogenic disturbance is necessary to produce dust from the vegetated landscape in the eastern Great Basin, as evidenced by the new dust source active from 2008 to 2010 in the area burned by the 2007 Milford Flat Fire; this fire was the largest in Utah's history due to extensive cover of invasive cheatgrass (Bromus tectorum) along with drought conditions. However, dust mobilization from the Milford Flat Burned Area was limited to regions that had been significantly disturbed by post-fire land management techniques that consisted of seeding, followed by chaining or tilling of the soil. Dust storms in the eastern

  4. Effectiveness of post-fire seeding at the Fitzner-Eberhardt Arid Land Ecology Reserve, Washington

    USGS Publications Warehouse

    Wirth, Troy A.; Pyke, David A.

    2011-01-01

    In August 2007, the Milepost 17 and Wautoma fires burned a combined total of 77,349 acres (31,302 hectares) of the Fitzner-Eberhardt Arid Land Ecology Reserve (ALE), part of the Hanford Reach National Monument administered by the U.S. Fish and Wildlife Service (USFWS) Mid-Columbia National Wildlife Refuge. In 2009, the USFWS implemented a series of seeding and herbicide treatments to mitigate potential negative consequences of these fires, including mortality of native vegetation, invasion of Bromus tectorum (cheatgrass), and soil erosion. Treatments included combinations of seeding (drill and aerial), herbicides, and one of six different mixtures of species. Artemisia tridentata ssp. wyomingensis (Wyoming big sagebrush) also was planted by hand in a small area in the southern end of the fire perimeter. Due to differences in plant communities prior to the fire and the multiple treatments applied, treatments were grouped into five treatment associations including mid-elevation aerial seedings, low-elevation aerial seedings, low-elevation drill seedings, high-elevation drill seeding, and no seeding treatments. Data collected at the mid-elevation aerial seedings indicate that the seeding did not appear to increase the density of seedlings compared to the non-seeded area in 2010. At the low-elevation aerial seedings, there were significantly more seedlings at seeded areas as compared to non-seeded areas. Low densities of existing perennial plants probably fostered a low-competition environment enabling seeds to germinate and emerge in 2010 during adequate moisture. Low-elevation drill seedings resulted in significant emergence of seeded grasses in 2009 and 2010 and forbs in 2010. This was likely due to adequate precipitation and that the drill seeding assured soil-to-seed contact. At the high-elevation drill seeding, which was implemented in 2009, there were a high number of seedlings in 2010. Transplanting of A. tridentata following the fires resulted in variable

  5. Predicting foundation bunchgrass species abundances: Model-assisted decision-making in protected-area sagebrush steppe

    USGS Publications Warehouse

    Rodhouse, Thomas J.; Irvine, Kathryn M.; Sheley, Roger L.; Smith, Brenda S.; Hoh, Shirley; Esposito, Daniel M.; Mata-Gonzalez, Ricardo

    2014-01-01

    Foundation species are structurally dominant members of ecological communities that can stabilize ecological processes and influence resilience to disturbance and resistance to invasion. Being common, they are often overlooked for conservation but are increasingly threatened from land use change, biological invasions, and over-exploitation. The pattern of foundation species abundances over space and time may be used to guide decision-making, particularly in protected areas for which they are iconic. We used ordinal logistic regression to identify the important environmental influences on the abundance patterns of bluebunch wheatgrass (Pseudoroegneria spicata), Thurber's needlegrass (Achnatherum thurberianum), and Sandberg bluegrass (Poa secunda) in protected-area sagebrush steppe. We then predicted bunchgrass abundances along gradients of topography, disturbance, and invasive annual grass abundance. We used model predictions to prioritize the landscape for implementation of a management and restoration decision-support tool. Models were fit to categorical estimates of grass cover obtained from an extensive ground-based monitoring dataset. We found that remnant stands of abundant wheatgrass and bluegrass were associated with steep north-facing slopes in higher and more remote portions of the landscape outside of recently burned areas where invasive annual grasses were less abundant. These areas represented only 25% of the landscape and were prioritized for protection efforts. Needlegrass was associated with south-facing slopes, but in low abundance and in association with invasive cheatgrass (Bromus tectorum). Abundances of all three species were strongly negatively correlated with occurrence of another invasive annual grass, medusahead (Taeniatherum caput-medusae). The rarity of priority bunchgrass stands underscored the extent of degradation and the need for prioritization. We found no evidence that insularity reduced invasibility; annual grass invasion represents

  6. Range-wide patterns of greater sage-grouse persistence

    USGS Publications Warehouse

    Aldridge, C.L.; Nielsen, S.E.; Beyer, H.L.; Boyce, M.S.; Connelly, J.W.; Knick, S.T.; Schroeder, M.A.

    2008-01-01

    population growth and peripherality of populations. However, future range loss may relate less to historical mechanisms and more to recent changes in land use and habitat condition, including energy developments and invasions by non-native species such as cheatgrass (Bromus tectorum) and West Nile virus. In conjunction with local measures of population performance, landscape-scale predictions of future range loss may be useful for prioritizing management and protection. Our results suggest that initial conservation efforts should focus on maintaining large expanses of sagebrush habitat, enhancing quality of existing habitats, and increasing habitat connectivity.

  7. Polycyclic aromatic hydrocarbons in biomass-burning emissions and their contribution to light absorption and aerosol toxicity.

    PubMed

    Samburova, Vera; Connolly, Jessica; Gyawali, Madhu; Yatavelli, Reddy L N; Watts, Adam C; Chakrabarty, Rajan K; Zielinska, Barbara; Moosmüller, Hans; Khlystov, Andrey

    2016-10-15

    In recent years, brown carbon (BrC) has been shown to be an important contributor to light absorption by biomass-burning atmospheric aerosols in the blue and near-ultraviolet (UV) part of the solar spectrum. Emission factors and optical properties of 113 polycyclic aromatic hydrocarbons (PAHs) were determined for combustion of five globally important fuels: Alaskan, Siberian, and Florida swamp peat, cheatgrass (Bromus tectorum), and ponderosa pine (Pinus ponderosa) needles. The emission factors of total analyzed PAHs were between 1.9±0.43.0±0.6 and 9.6±1.2-42.2±5.4mgPAHkg(-1)fuel for particle- and gas phase, respectively. Spectrophotometric analysis of the identified PAHs showed that perinaphthenone, methylpyrenes, and pyrene contributed the most to the total PAH light absorption with 17.2%, 3.3 to 10.5%, and 7.6% of the total particle-phase PAH absorptivity averaged over analyzed emissions from the fuels. In the gas phase, the top three PAH contributors to BrC were acenaphthylene (32.6%), anthracene (8.2%), and 2,4,5-trimethylnaphthalene (8.0%). Overall, the identified PAHs were responsible for 0.087-0.16% (0.13% on average) and 0.033-0.15% (0.11% on average) of the total light absorption by dichloromethane-acetone extracts of particle and gas emissions, respectively. Toxic equivalency factor (TEF) analysis of 16 PAHs prioritized by the United States Environmental Protection Agency (EPA) showed that benzo(a)pyrene contributed the most to the PAH carcinogenic potency of particle phase emissions (61.8-67.4% to the total carcinogenic potency of Σ16EPA PAHs), while naphthalene played the major role in carcinogenicity of the gas phase PAHs in the biomass-burning emission analyzed here (35.4-46.0% to the total carcinogenic potency of Σ16EPA PAHs). The 16 EPA-prioritized PAHs contributed only 22.1±6.2% to total particle and 23.4±11% to total gas phase PAH mass, thus toxic properties of biomass-burning PAH emissions are most likely underestimated. PMID:27304373

  8. Lack of Host Specialization on Winter Annual Grasses in the Fungal Seed Bank Pathogen Pyrenophora semeniperda.

    PubMed

    Beckstead, Julie; Meyer, Susan E; Ishizuka, Toby S; McEvoy, Kelsey M; Coleman, Craig E

    2016-01-01

    Generalist plant pathogens may have wide host ranges, but many exhibit varying degrees of host specialization, with multiple pathogen races that have narrower host ranges. These races are often genetically distinct, with each race causing highest disease incidence on its host of origin. We examined host specialization in the seed pathogen Pyrenophora semeniperda by reciprocally inoculating pathogen strains from Bromus tectorum and from four other winter annual grass weeds (Bromus diandrus, Bromus rubens, Bromus arvensis and Taeniatherum caput-medusae) onto dormant seeds of B. tectorum and each alternate host. We found that host species varied in resistance and pathogen strains varied in aggressiveness, but there was no evidence for host specialization. Most variation in aggressiveness was among strains within populations and was expressed similarly on both hosts, resulting in a positive correlation between strain-level disease incidence on B. tectorum and on the alternate host. In spite of this lack of host specialization, we detected weak but significant population genetic structure as a function of host species using two neutral marker systems that yielded similar results. This genetic structure is most likely due to founder effects, as the pathogen is known to be dispersed with host seeds. All host species were highly susceptible to their own pathogen races. Tolerance to infection (i.e., the ability to germinate even when infected and thereby avoid seed mortality) increased as a function of seed germination rate, which in turn increased as dormancy was lost. Pyrenophora semeniperda apparently does not require host specialization to fully exploit these winter annual grass species, which share many life history features that make them ideal hosts for this pathogen. PMID:26950931

  9. Lack of Host Specialization on Winter Annual Grasses in the Fungal Seed Bank Pathogen Pyrenophora semeniperda

    PubMed Central

    Beckstead, Julie; Meyer, Susan E.; Ishizuka, Toby S.; McEvoy, Kelsey M.; Coleman, Craig E.

    2016-01-01

    Generalist plant pathogens may have wide host ranges, but many exhibit varying degrees of host specialization, with multiple pathogen races that have narrower host ranges. These races are often genetically distinct, with each race causing highest disease incidence on its host of origin. We examined host specialization in the seed pathogen Pyrenophora semeniperda by reciprocally inoculating pathogen strains from Bromus tectorum and from four other winter annual grass weeds (Bromus diandrus, Bromus rubens, Bromus arvensis and Taeniatherum caput-medusae) onto dormant seeds of B. tectorum and each alternate host. We found that host species varied in resistance and pathogen strains varied in aggressiveness, but there was no evidence for host specialization. Most variation in aggressiveness was among strains within populations and was expressed similarly on both hosts, resulting in a positive correlation between strain-level disease incidence on B. tectorum and on the alternate host. In spite of this lack of host specialization, we detected weak but significant population genetic structure as a function of host species using two neutral marker systems that yielded similar results. This genetic structure is most likely due to founder effects, as the pathogen is known to be dispersed with host seeds. All host species were highly susceptible to their own pathogen races. Tolerance to infection (i.e., the ability to germinate even when infected and thereby avoid seed mortality) increased as a function of seed germination rate, which in turn increased as dormancy was lost. Pyrenophora semeniperda apparently does not require host specialization to fully exploit these winter annual grass species, which share many life history features that make them ideal hosts for this pathogen. PMID:26950931

  10. A Chronosequence Feasibility Assessment of Emergency Fire Rehabilitation Records within the Intermountain Western United States - Final Report to the Joint Fire Science Program - Project 08-S-08

    USGS Publications Warehouse

    Knutson, Kevin C.; Pyke, David A.; Wirth, Troy A.; Pilliod, David S.; Brooks, Matthew L.; Chambers, Jeanne C.

    2009-01-01

    Department of the Interior (DOI) bureaus have invested heavily (for example, the U.S. Bureau of Land Management (BLM) spent more than $60 million in fiscal year 2007) in seeding vegetation for emergency stabilization and burned area rehabilitation of non-forested arid lands over the past 10 years. The primary objectives of these seedings commonly are to (1) reduce the post-fire dominance of non-native annual grasses, such as cheatgrass (Bromus tectorum) and red brome (Bromus rubens); (2) minimize the probability of recurrent fire; and (3) ultimately produce desirable vegetation characteristics (for example, ability to recover following disturbance [resilience], resistance to invasive species, and a capacity to support a diverse flora and fauna). Although these projects historically have been monitored to varying extents, land managers currently lack scientific evidence to verify whether seeding arid and semiarid lands achieves desired objectives. Given the amount of resources dedicated to post-fire seeding projects, a synthesis of information determining the factors that result in successful treatments is critically needed. Although results of recently established experiments and monitoring projects eventually will provide useful insights for the future direction of emergency stabilization and burned area rehabilitation programs, a chronosequence approach evaluating emergency stabilization and burned area rehabilitation treatments (both referenced hereafter as ESR treatments) over the past 30 years could provide a comprehensive assessment of treatment success across a range of regional environmental gradients. By randomly selecting a statistically robust sample from the population of historic ESR treatments in the Intermountain West, this chronosequence approach would have inference for most ecological sites in this region. The goal of this feasibility study was to compile and examine historic ESR records from BLM field offices across the Intermountain West to