Phytotoxic activity against Bromus tectorum for secondary metabolites of a seed-pathogenic Fusarium strain belonging to the F. tricinctum species complex

Treesearch

Marco Masi; Susan Meyer; Gennaro Pescitelli; Alessio Cimmino; Suzette Clement; Beth Peacock; Antonio Evidente

2017-01-01

The winter annual grass Bromus tectorum (cheatgrass) has become highly invasive in semiarid ecosystems of western North America. In these areas, a natural phenomenon, complete cheatgrass stand failure (‘die-off’), is apparently caused by a complex interaction among soilborne fungal pathogens. Several Fusarium strains belonging to the Fusarium tricinctum species complex...

Development of remote sensing indicators for mapping episodic die-off of an invasive annual grass (Bromus tectorum) from the Landsat archive

Treesearch

Peter J. Weisberg; Thomas E. Dilts; Owen W. Baughman; Susan E. Meyer; Elizabeth A. Leger; K. Jane Van Gunst; Lauren Cleeves

2017-01-01

The exotic annual grass Bromus tectorum (cheatgrass) dominates vast acreages of rangeland in the western USA, leading to increased fire frequency and ecosystem degradation that is often irreversible. Episodic regeneration failure (“die-off”) has been observed in cheatgrass monocultures and can have negative ecosystem consequences, but can also provide an opportunity...

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

Does Fusarium-caused seed mortality contribute to Bromus tectorum stand failure in the Great Basin?

Treesearch

S. E. Meyer; J.-L. Franke; O. W. Baughman; J. Beckstead; B. Geary

2014-01-01

Bromus tectorum (cheatgrass, downy brome) is an important invader in western North America, dominating millions of hectares of former semi-arid shrubland. Stand failure or 'die-off' is relatively common in monocultures of this annual grass. The study reported here investigated whether soil-borne pathogens could be causal agents in die-offs. Soils from two die...

Rehabilitation of cheatgrass infested rangelands

USDA-ARS?s Scientific Manuscript database

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...

Cheatgrass invasion and wildlife habitat

USDA-ARS?s Scientific Manuscript database

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...

Rehabilitation of cheatgrass-infested rangelands

USDA-ARS?s Scientific Manuscript database

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...

Phytotoxic activity against Bromus tectorum for secondary metabolites of a seed-pathogenic Fusarium strain belonging to the F. tricinctum species complex.

PubMed

Masi, Marco; Meyer, Susan; Pescitelli, Gennaro; Cimmino, Alessio; Clement, Suzette; Peacock, Beth; Evidente, Antonio

2017-12-01

The winter annual grass Bromus tectorum (cheatgrass) has become highly invasive in semiarid ecosystems of western North America. In these areas, a natural phenomenon, complete cheatgrass stand failure ('die-off'), is apparently caused by a complex interaction among soilborne fungal pathogens. Several Fusarium strains belonging to the Fusarium tricinctum species complex were isolated from these soils and found to be pathogenic on B. tectorum seeds. One of these strains was produced in cheatgrass seed culture to evaluate its ability to produce phytotoxins. Six metabolites were isolated and identified by spectroscopic methods (essentially 1D and 2D NMR and ESIMS) as acuminatopyrone (1), blumenol A (2), chlamydosporol (3), isochlamydosporol (4), ergosterol (5) and 4-hydroxybenzaldehyde (6). Upon testing against B. tectorum in a seedling bioassay, (6) the coleoptile and radicle length of cheatgrass seedlings were significantly reduced. Compounds 1 and 2 showed moderate activity, while 3-5 were not significantly different from the control.

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

Treesearch

Melissa A. Baynes; Danelle M. Russell; George Newcombe; Lynn K. Carta; Amy Y. Rossman; Adnan Ismaiel

2012-01-01

In its invaded range in western North America, Bromus tectorum (cheatgrass) can host more than 100 sequence-based, operational taxonomic units of endophytic fungi, of which an individual plant hosts a subset. Research suggests that the specific subset is determined by plant genotype, environment, dispersal of locally available endophytes, and mycorrhizal associates....

Cheatgrass control and seeding: lessons learned

USDA-ARS?s Scientific Manuscript database

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 ch...

Rehabilitation of cheatgrass infested rangelands: an integrated approach

USDA-ARS?s Scientific Manuscript database

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 ...

Integrated approach to cheatgrass suppression on great basin rangelands

USDA-ARS?s Scientific Manuscript database

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...

The use of plant material testing to successfully suppress cheatgrass

USDA-ARS?s Scientific Manuscript database

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...

Managing cheatgrass in rangeland restoration efforts

USDA-ARS?s Scientific Manuscript database

The accidental introduction and subsequent invasion of cheatgrass (Bromus tectorum) onto millions of acres of Intermountain west rangelands has significantly affected the ability of resource managers and land owners to effectively restore or rehabilitate disturbed rangelands. The Nevada Section-Soci...

Factors mediating cheatgrass invasion of intact salt desert shrubland

Treesearch

Susan E. Meyer; Susan C. Garvin; Julie Beckstead

2001-01-01

Cheatgrass (Bromus tectorum) has recently displaced salt desert shrubland in many areas of the Great Basin. We studied the dynamics of cheatgrass invasion into an intact shadscale-gray molly community in Dugway Valley, Utah, by adding seeds and manipulating disturbance regime and resource availability. Shrub clipping or cryptobiotic crust trampling on large plots...

Cheatgrass - native plant community interactions in an invaded southwestern forest

Treesearch

Christopher M. McGlone

2010-01-01

Invasions by nonnative plant species such as cheatgrass (Bromus tectorum) are a major concern in many ecosystems worldwide. When invasive nonnative species dominate a new ecosystem, they can alter biodiversity, species composition, nutrient cycles, disturbance regimes, and other ecosystem functions and processes. In 2003, cheatgrass rapidly spread through the Mt....

Fire effects on the cheatgrass seed bank pathogen Pyrenophora semeniperda

Treesearch

Julie Beckstead; Laura E. Street; Susan E. Meyer; Phil S. Allen

2011-01-01

The generalist fungal pathogen Pyrenophora semeniperda occurs primarily in cheatgrass (Bromus tectorum) seed banks, where it causes high mortality. We investigated the relationship between this pathogen and its cheatgrass host in the context of fire, asking whether burning would facilitate host escape from the pathogen or increase host vulnerability. We used a series...

Rehabilitation of cheatgrass-infested rangelands: concepts

USDA-ARS?s Scientific Manuscript database

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 ...

Cheatgrass and red brome; the history and biology of two invaders

Treesearch

Chad R. Reid; Sherel Goodrich; James E. Bowns

2008-01-01

In recent history, there has not been a more ecologically important event than the introduction of cheatgrass (Bromus tectorum) and red brome (Bromus rubens) into the Intermountain West. These grasses are very similar in ecology and history and are separated mostly by function of elevation. Both species are from the Mediterranean...

Perennial grass establishment following cheatgrass control using herbicides

USDA-ARS?s Scientific Manuscript database

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...

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

USDA-ARS?s Scientific Manuscript database

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 ...

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.

Imazapic, rimsulfuron, and sulfometuron methyl effectiveness at controlling cheatgrass

USDA-ARS?s Scientific Manuscript database

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...

Rehabilitation of cheatgrass-infested rangelands: applications and practices

USDA-ARS?s Scientific Manuscript database

The challenges that land owners and resource managers face when trying to attempt applications and practices when attempting to rehabilitate rangelands infested with cheatgrass (Bromus tectorum) are over-whelming. Simply purchasing seed and spreading it throughout the rangelands is doomed for failu...

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

USDA-ARS?s Scientific Manuscript database

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...

Evidence that invasion by cheatgrass alters soil nitrogen availability

USDA-ARS?s Scientific Manuscript database

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...

Rehabilitation and Cheatgrass Suppression Following Great Basin Wildfires

USDA-ARS?s Scientific Manuscript database

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...

Improving seeding success on cheatgrass-infested rangelands in Northern Nevada

USDA-ARS?s Scientific Manuscript database

Invasion of alien plant species influences all phases of wildland research in the Great Basin. The accidental introduction and subsequent invasion of cheatgrass (Bromus tectorum L.) onto millions of hectares of Great Basin rangelands has led to the conversion of former big sagebrush (Artemisia tride...

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.

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

Abiotic and biotic influences on Bromus tectoreum invasion and Artemisia tridentata recovery after fire

Treesearch

Lea Condon; Peter J. Weisberg; Jeanne C. Chambers

2011-01-01

Native sagebrush ecosystems in the Great Basin (western USA) are often invaded following fire by exotic Bromus tectorum (cheatgrass), a highly flammable annual grass. Once B. tectorum is established, higher fire frequencies can lead to local extirpation of Artemisia tridentata ssp. vaseyana (mountain big sagebrush) and have cascading effects on sagebrush ecosystems and...

Prediction of cheatgrass field germination potential using wet thermal accumulation

Treesearch

Bruce A. Roundy; Stuart P. Hardegree; Jeane C. Chambers; Alison Whittaker

2007-01-01

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.) germination in big sagebrush (Artemisia...

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

USDA-ARS?s Scientific Manuscript database

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...

Shrub establishment in the presence of cheatgrass: The effect of soil microorganisms

Treesearch

Rosemary L. Pendleton; Burton K. Pendleton; Steven D. Warren; Jeffrey R. Johansen; Larry L. St. Clair

2007-01-01

Invasive annual grasses, such as cheatgrass (Bromus tectorum), create changes in soil microorganism communities and severely limit shrub establishment, a situation that is of considerable inportance to land managers. We examined the effects of biological crustforming algae and arbuscular mycorrhizal fungi on growth and survival of Ephedra...

Respiratory and physiological characteristics in subpopulations of Great Basin cheatgrass

Treesearch

V. Wallace McCarlie; Lee D. Hansen; Bruce N. Smith

2001-01-01

Cheatgrass (Bromus tectorum L.) is a dominant weed that has increased the frequency of wildfire in the Great Basin since its introduction approximately 106 years ago. Characteristics of respiratory metabolism were examined in eleven subpopulations from different habitats. Seeds from each subpopulation were germinated (4mm radicle) and metabolic heat rates (q) and...

Impacts of native grasses and cheatgrass on Great Basin forb development

Treesearch

Hillary Ann Parkinson

2008-01-01

Land managers need more information on native forb growth and interactions between forbs and grasses to improve degraded sagebrush steppe habitats in the Great Basin, and to increase the diversity of revegetation seed mixes. This is especially important in areas infested with Bromus tectorum (cheatgrass), an annual grass present in more than 100...

Competitive effects of bluebunch wheatgrass, crested wheatgrass, and cheatgrass on antelope bitterbrush seedling emergence and survival

Treesearch

Derek B. Hall; Val Jo Anderson; Stephen B. Monsen

1999-01-01

The competitive environment into which plant seedlings emerge often determines the survival and performance of these individuals. This study was designed to determine the effects of bluebunch wheatgrass (Pseudoroegneria spicata), crested wheatgrass (Agropyron cristatum), and cheatgrass (Bromus tectorum) on soil...

Effects of nitrogen availability and cheatgrass competition on the establishment of Vavilov Siberian wheatgrass

Treesearch

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

2008-01-01

Cheatgrass (Bromus tectorum L.) is the most widespread invasive weed in sagebrush ecosystems of North America. Restoration of perennial vegetation is difficult and land managers have often used introduced bunchgrasses to restore degraded sagebrush communities. Our objective was to evaluate the potential of 'Vavilov' Siberian wheatgrass (Agropyron fragile [...

Using state-and-transition models to project cheatgrass and juniper invasion in Southeastern Oregon sagebrush steppe

Treesearch

Megan K. Creutzburg; Joshua S. Halofsky; Miles A. Hemstrom

2012-01-01

Many threats are jeopardizing the sagebrush steppe of the Columbia Basin, including the spread of invasive species such as cheatgrass (Bromus tectorum L.) and the expansion of western juniper (Juniperus occidentalis Hook.) into historic shrub steppe. Native sagebrush steppe provides productive grazing lands and important...

Induction and release of secondary dormancy under field conditions in Bromus tectorum

Treesearch

Phil S. Allen; S. E. Meyer; K. Foote

2010-01-01

Bromus tectorum L. is a facultative winter annual grass originally from Eurasia. During the past century, this species has become highly invasive in the western United States, where it has displaced millions of hectares of native vegetation. Seeds of B. tectorum lose primary dormancy through dry after-ripening, and nearly all seeds are capable of germinating in...

Exotic cheatgrass and loss of soil biota decrease the performance of a native grass

Treesearch

Suzanne M. Owen; Carolyn Hull Sieg; Nancy Collins Johnson; Catherine A. Gehring

2013-01-01

Soil disturbances can alter microbial communities including arbuscular mycorrhizal (AM) fungi, which may in turn, affect plant community structure and the abundance of exotic species. We hypothesized that altered soil microbial populations owing to disturbance would contribute to invasion by cheatgrass (Bromus tectorum), an exotic annual grass, at the expense of the...

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.

Near-real-time cheatgrass percent cover in the Northern Great Basin, USA, 2015

USGS Publications Warehouse

Boyte, Stephen; Wylie, Bruce K.

2016-01-01

Cheatgrass (Bromus tectorum L.) dramatically changes shrub steppe ecosystems in the Northern Great Basin, United States.Current-season cheatgrass location and percent cover are difficult to estimate rapidly.We explain the development of a near-real-time cheatgrass percent cover dataset and map in the Northern Great Basin for the current year (2015), display the current year’s map, provide analysis of the map, and provide a website link to download the map (as a PDF) and the associated dataset.The near-real-time cheatgrass percent cover dataset and map were consistent with non-expedited, historical cheatgrass percent cover datasets and maps.Having cheatgrass maps available mid-summer can help land managers, policy makers, and Geographic Information Systems personnel as they work to protect socially relevant areas such as critical wildlife habitats.

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

USDA-ARS?s Scientific Manuscript database

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...

Learning to live with cheatgrass: Giving up or a necessary paradigm shift?

Treesearch

Stanley G. Kitchen

2014-01-01

Natural ecosystems in the semiarid West face many stressors. Among the most challenging are those associated with invasive plant species. One invader that has had great impact over the last 100 years is the annual grass known as cheatgrass (Bromus tectorum). A few years ago, I made two observations that both confirmed and broadened my perception of this plant. In the...

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

USDA-ARS?s Scientific Manuscript database

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 ...

Development of single-nucleotide polymorphism markers for Bromus tectorum (Poaceae) from a partially sequenced transcriptome

Treesearch

Keith R. Merrill; Craig E. Coleman; Susan E. Meyer; Elizabeth A. Leger; Katherine A. Collins

2016-01-01

Premise of the study: Bromus tectorum (Poaceae) is an annual grass species that is invasive in many areas of the world but most especially in the U.S. Intermountain West. Single-nucleotide polymorphism (SNP) markers were developed for use in investigating the geospatial and ecological diversity of B. tectorum in the Intermountain West to better understand the...

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

Environmental factors influencing Pyrenophora semeniperda-caused seed mortality in Bromus tectorum

Treesearch

Heather Finch; Phil S. Allen; Susan E. Meyer

2013-01-01

Temperature and water potential strongly influence seed dormancy status and germination of Bromus tectorum. As seeds of this plant can be killed by the ascomycete fungus Pyrenophora semeniperda, this study was conducted to learn how water potential and temperature influence mortality levels in this pathosystem. Separate experiments were conducted to determine: (1) if P...

Pyrenophoric acids B and C, two new phytotoxic sesquiterpenoids produced by Pyrenophora semeniperda

Treesearch

Marco Masi; Susan Meyer; Alessio Cimmino; Suzette Clement; Beth Black; Antonio Evidente

2014-01-01

Two new phytotoxic sesquiterpenoid acids, named pyrenophoric acids B and C, were isolated together with the related pyrenophoric and abscisic acids from solid Bromus tectorum (cheatgrass) seed culture of the seed pathogen Pyrenophora semeniperda. This fungus has been proposed as a mycoherbicide for biocontrol of cheatgrass (Bromus tectorum), a Eurasian annual grass...

Impact of the pathogen Pyrenophora semeniperda on Bromus tectorum seedbank dynamics in North American cold deserts

Treesearch

S. E. Meyer; D. Quinney; D. L. Nelson; J. Weaver

2007-01-01

Bromus tectorum is a dominant winter annual weed in cold deserts of western North America. We followed patterns of seed carry-over and abundance of the pathogen Pyrenophora semeniperda over 5 years at B. tectorum-dominated shadscale (Atriplex confertifolia) and sagebrush (Artemisia tridentata) sites in southern Idaho. We hypothesised that more seeds could potentially...

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

USDA-ARS?s Scientific Manuscript database

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...

Cheatgrass die-offs as an opportunity for restoration in the Great Basin, USA: Will local or commercial native plants succeed where exotic invaders fail?

Treesearch

Owen W. Baughman; Susan E. Meyer; Zachary T. Aanderud; Elizabeth A. Leger

2016-01-01

Bromus tectorum (cheatgrass) has widely invaded the Great Basin, U.S.A. The sporadic natural phenomenon of complete stand failure ('die-off'') of this invader may present opportunities to restore native plants. A recent die-off in Nevada was precision-planted with seeds of the native grasses Poa secunda (Sandberg bluegrass) and Elymus elymoides (...

Strong genetic differentiation in the invasive annual grass Bromus tectorum across the Mojave-Great Basin ecological transition zone

Treesearch

Susan E. Meyer; Elizabeth A. Leger; Desiree R. Eldon; Craig E. Coleman

2016-01-01

Bromus tectorum, an inbreeding annual grass, is a dominant invader in sagebrush steppe habitat in North America. It is also common in warm and salt deserts, displaying a larger environmental tolerance than most native species. We tested the hypothesis that a suite of habitat-specific B. tectorum lineages dominates warm desert habitats. We sampled 30 B....

Short-term effects of rainfall on CO2 fluxes above rangelands dominated by Artemisia, Bromus tectorum, and Agropyron

NASA Astrophysics Data System (ADS)

Ivans, S.; Saliendra, N. Z.; Johnson, D. A.

2003-04-01

The short-term effects of rainfall on carbon dioxide (CO_2) fluxes have not been well documented in rangelands of the Intermountain Region of the western USA. We used the Bowen ratio-energy balance technique to continuously measure CO_2 fluxes above three rangeland sites in Idaho and Utah dominated by: 1) Artemisia (sagebrush) near Malta, Idaho; 2) Bromus tectorum (cheatgrass) near Malta, Idaho; and 3) Agropyron (crested wheatgrass) in Rush Valley, Utah. We examined CO_2 fluxes immediately before and after rainfall during periods of 10--19 July 2001 (Summer), 8--17 October 2001 (Autumn), and 16--30 May 2002 (Spring). On sunny days before rainfall during Spring, all three sites were sinks for CO_2. After rainfall in Spring, all three sites became sources of CO_2 for about two days and after that became CO_2 sinks again. During Summer and Autumn when water was limiting, sites were small sources of CO_2 and became larger sources for one day after rainfall. In all three seasons, daytime CO_2 fluxes decreased and nighttime CO_2 fluxes increased after rainfall, suggesting that rainfall stimulated belowground respiration at all three sites. Results from this study indicated that CO_2 fluxes above rangeland sites in the Intermountain West changed markedly after rainfall, especially during Spring when fluxes were highest. KEY WORDS: Bowen ratio-energy balance, Intermountain West, rangelands, sagebrush, cheatgrass, crested wheatgrass

A hydrothermal after-ripening time model for seed dormancy loss in Bromus tectorum L.

Treesearch

Necia B. Bair; Susan E. Meyer; Phil S. Allen

2006-01-01

After-ripening, the loss of dormancy under dry conditions, is associated with a decrease in mean base water potential for germination of Bromus tectorum L. seeds. After-ripening rate is a linear function of temperature above a base temperature, so that dormancy loss can be quantified using a thermal after-ripening time (TAR) model. To incorporate storage water...

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.

Spatio-temporal heterogeneity and habitat invasibility in sagebrush steppe ecosystems

Treesearch

Monica B. Mazzola

2008-01-01

Bromus tectorum L. (cheatgrass) is the most widespread invasive weed in sagebrushsteppe ecosystems. Invasion by Bromus tectorum produces large-scale changes ecosystem that negatively affect seedling establishment processes. Establishment of invasive and native species plays a key role in determining community invasibility and restoration potential. This study examined...

Ecological genetics of the Bromus tectorum (Poaceae) - Ustilago Bullata (Ustilaginaceae): A role for frequency dependent selection?

Treesearch

Susan E. Meyer; David L. Nelson; Suzette Clement; Alisa Ramakrishnan

2010-01-01

Evolutionary processes that maintain genetic diversity in plants are likely to include selection imposed by pathogens. Negative frequency-dependent selection is a mechanism for maintenance of resistance polymorphism in plant - pathogen interactions. We explored whether such selection operates in the Bromus tectorum - Ustilago bullata pathosystem. Gene-for-gene...

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

USDA-ARS?s Scientific Manuscript database

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...

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

USDA-ARS?s Scientific Manuscript database

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...

Population genetic structure of the seed pathogen Pyrenophora semeniperda on Bromus tectorum in western North America

Treesearch

David Boose; Steven Harrison; Suzette Clement; Susan E. Meyer

2011-01-01

We examined genetic variation in the ascomycete pathogen Pyrenophora semeniperda cultured from seeds of the invasive grass Bromus tectorum in the Intermountain West of North America. We sequenced the internal transcribed spacer (ITS) region of the nuclear ribosomal RNA genome in 417 monoconidial cultures collected from 20 sites in Washington, Idaho, Utah and Colorado,...

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

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

PubMed

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

2013-05-01

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

Combustion properties of Bromus tectorum L.: influence of ecotype and growth under four CO2 concentrations

Treesearch

Robert R. Blank; Robert H. White; Lewis H. Ziska

2006-01-01

We grew from seed the exotic invasive annual grass Bromus tectorum L., collected from three elevation ecotypes in northern Nevada, USA. Plants were exposed to four CO2 atmosphere concentrations: 270, 320, 370, and 420 [mu]mol mol−1. After harvest on day 87, above-ground tissue was milled, conditioned to 30% relative humidity, and combustion properties were...

A race for survival: Can Bromus tectorum seeds escape Pyrenophora semeniperda-caused mortality by germinating quickly?

Treesearch

Julie Beckstead; Susan E. Meyer; Cherrilyn J. Molder; Caitlyn Smith

2007-01-01

Pathogen-seed interactions may involve a race for seed resources, so that seeds that germinate more quickly, mobilizing reserves, will be more likely to escape seed death than slow-germinating seeds. This race-for-survival hypothesis was tested for the North American seed pathogen Pyrenophora semeniperda on seeds of the annual grass Bromus tectorum, an invasive plant...

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.

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.

Population genetic analysis of Bromus tectorum (Poaceae) indicates recent range expansion may be facilitated by specialist genotypes

Treesearch

Keith R. Merrill; Susan E. Meyer; Craig E. Coleman

2012-01-01

The mechanisms for range expansion in invasive species depend on how genetic variation is structured in the introduced range. This study examined neutral genetic variation in the invasive annual grass Bromus tectorum in the Intermountain Western United States. Patterns of microsatellite (SSR) genotype distribution in this highly inbreeding species were used to make...

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.

Soils conditioned by native vegetation and by the exotic invasive annual grass Bromus tectorum: do a native perennial and two exotic grasses sense the substrates similarly

USDA-ARS?s Scientific Manuscript database

Invasion by the exotic annual grass Bromus tectorum often increases soil nutrient availability. It is unclear, however, if other grasses benefit from this higher nutrient status. Soil from three sites in the northern Great Basin U.S.A. conditioned by B. tectoruminvasion (BTCS=B. tectorum conditioned...

Herbicide efficacy and perennial grass establishment

USDA-ARS?s Scientific Manuscript database

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...

Secondary dormancy induction and release in Bromus tectorum seeds: The role of temperature, water potential and hydrothermal time

Treesearch

K. K. Hawkins; P. S. Allen; Susan Meyer

2017-01-01

Seeds of the winter annual Bromus tectorum lose primary dormancy in summer and are poised to germinate rapidly in the autumn. If rainfall is inadequate, seeds remain ungerminated and may enter secondary dormancy under winter conditions. We quantified conditions under which seeds enter secondary dormancy in the laboratory and field and also examined whether contrasting...

Effects of climate and snow depth on Bromus tectorum population dynamics at high elevation.

PubMed

Griffith, Alden B; Loik, Michael E

2010-11-01

Invasive plants are thought to be especially capable of range shifts or expansion in response to climate change due to high dispersal and colonization abilities. Although highly invasive throughout the Intermountain West, the presence and impact of the grass Bromus tectorum has been limited at higher elevations in the eastern Sierra Nevada, potentially due to extreme wintertime conditions. However, climate models project an upward elevational shift of climate regimes in the Sierra Nevada that could favor B. tectorum expansion. This research specifically examined the effects of experimental snow depth manipulations and interannual climate variability over 5 years on B. tectorum populations at high elevation (2,175 m). Experimentally-increased snow depth had an effect on phenology and biomass, but no effect on individual fecundity. Instead an experimentally-increased snowpack inhibited population growth in 1 year by reducing seedling emergence and early survival. A similar negative effect of increased snow was observed 2 years later. However, a strong negative effect on B. tectorum was also associated with a naturally low-snow winter, when seedling emergence was reduced by 86%. Across 5 years, winters with greater snow cover and a slower accumulation of degree-days coincided with higher B. tectorum seedling density and population growth. Thus, we observed negative effects associated with both experimentally-increased and naturally-decreased snowpacks. It is likely that the effect of snow at high elevation is nonlinear and differs from lower elevations where wintertime germination can be favorable. Additionally, we observed a doubling of population size in 1 year, which is alarming at this elevation.

Rehabilitation of degraded rangelands: lessons learned

USDA-ARS?s Scientific Manuscript database

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...

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.

Assessment of horse creek conservation seeding

USDA-ARS?s Scientific Manuscript database

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, ...

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

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

Downy Brome: evidence for soil engineering

USDA-ARS?s Scientific Manuscript database

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...

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

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.

Germination phenology of some Great Basin native annual forb species

Treesearch

Tara A. Forbis

2010-01-01

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 at many sites. Germination timing is often an important predictor of competitive...

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

Indirect effects of an invasive annual grass on seed fates of two native perennial grass species

Treesearch

Susan E. Meyer; Katherine T. Merrill; Phil S. Allen; Julie Beckstead; Anna S. Norte

2014-01-01

Invasive plants exhibit both direct and indirect negative effects on recruitment of natives following invasion. We examined indirect effects of the invader Bromus tectorum (cheatgrass) on seed fates of two native grass species, Elymus elymoides and Pseudoroegneria spicata, by removing B. tectorum and by adding inoculum of the shared seed pathogen Pyrenophora...

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.

De novo genome assembly of the fungal plant pathogen Pyrenophora semeniperda

Treesearch

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

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...

Soil biota in an ungrazed grassland: Response to annual grass (Bromus tectorum) invasion

USGS Publications Warehouse

Belnap, Jayne; Phillips, Susan L.

2001-01-01

Bromus tectorum is an exotic annual grass that currently dominates many western U.S. semi-arid ecosystems, and the effects of this grass on ecosystems in general, and soil biota specifically, are unknown. Bromus recently invaded two ungrazed and unburned perennial bunchgrass communities in southeastern Utah. This study compared the soil food-web structure of the two native grassland associations (Stipa [S] and Hilaria [H]), with and without the presence of Bromus. Perennial grass and total vascular-plant cover were higher in S than in H plots, while quantities of ground litter were similar. Distribution of live and dead plant material was highly clumped in S and fairly homogenous in H. Soil food-web structure was different between H and S, with lower trophic levels more abundant in H and higher trophic levels more abundant in S. In Bromus-invaded plots, the quantity of ground litter was 2.2 times higher in Hilaria–Bromus (HB) than in H plots, and 2.8 times higher in Stipa–Bromus (SB) than in S plots. Soil biota in HB generally responded to the Bromus invasion in an opposite manner than in SB, e.g., if a given component of the food web increased in one community, it generally decreased in the other. Active bacteria decreased in H vs. HB, while increasing in S vs. SB. Soil and live plant-infecting fungi were the exception, as they increased in both types of invaded plots relative to uninvaded plots. Dead-plant-infecting fungi decreased in H vs. HB and increased in S vs. SB. Most higher-trophic-level organisms increased in HB relative to H, while decreasing in SB relative to S. Given the mixed response to invasion, the structure of these soil food webs appears to be controlled by both plant inputs and internal dynamics between trophic levels. When compared to non-invaded sites, soil and soil food-web characterisitics of the newly invaded sites included: (1) lower species richness and lower absolute numbers of fungi and invertebrates; (2) greater abundance of

Fungal and bacterial contributions to nitrogen cycling in cheatgrass-invaded and uninvaded native sagebrush soils of the western USA

USGS Publications Warehouse

DeCrappeo, Nicole; DeLorenze, Elizabeth J.; Giguere, Andrew T; Pyke, David A.; Bottomley, Peter J.

2017-01-01

AimThere is interest in determining how cheatgrass (Bromus tectorum L.) modifies N cycling in sagebrush (Artemisia tridentata Nutt.) soils of the western USA.MethodsTo gain insight into the roles of fungi and bacteria in N cycling of cheatgrass-invaded and uninvaded sagebrush soils, the fungal protein synthesis inhibitor, cycloheximide (CHX), and the bacteriocidal compound, bronopol (BRO) were combined with a 15NH4+ isotope pool dilution approach.ResultsCHX reduced gross N mineralization to the same rate in both sagebrush and cheatgrass soils indicating a role for fungi in N mineralization in both soil types. In cheatgrass soils BRO completely inhibited gross N mineralization, whereas, in sagebrush soils a BRO-resistant gross N mineralization rate was detected that was slower than CHX sensitive gross N mineralization, suggesting that the microbial drivers of gross N mineralization were different in sagebrush and cheatgrass soils. Net N mineralization was stimulated to a higher rate in sagebrush than in cheatgrass soils by CHX, implying that a CHX inhibited N sink was larger in the former than the latter soils. Initial gross NH4+ consumption rates were reduced significantly by both CHX and BRO in both soil types, yet, consumption rates recovered significantly between 24 and 48 h in CHX-treated sagebrush soils. The recovery of NH4+ consumption in sagebrush soils corresponded with an increase in the rate of net nitrification.ConclusionsThese results suggest that cheatgrass invasion of sagebrush soils of the northern Great Basin reduces the capacity of the fungal N consumption sink, enhances the capacity of a CHX resistant N sink and alters the contributions of bacteria and fungi to gross N mineralization.

A novel plant-fungal mutualism associated with fire

Treesearch

Melissa Baynes; George Newcombe; Linley Dixon; Lisa Castlebury; Kerry O' Donnell

2012-01-01

Bromus tectorum, or cheatgrass, is native to Eurasia and widely invasive in western North America. By late spring, this annual plant has dispersed its seed and died; its aboveground biomass then becomes fine fuel that burns as frequently as once every 3-5 y in its invaded range. Cheatgrass has proven to be better adapted to fire there than many competing plants, but...

Germination prediction from soil moisture and temperature in the Great Basin

USDA-ARS?s Scientific Manuscript database

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...

Characteristics that determine a successful squirreltail (Elymus elymoides)

USDA-ARS?s Scientific Manuscript database

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...

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

USDA-ARS?s Scientific Manuscript database

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...

Fire and grazing influence site resistance to Bromus tectorum through their effects on shrub, bunchgrass and biocrust communities in the Great Basin (USA)

USGS Publications Warehouse

Condon, Lea A.; Pyke, David A.

2018-01-01

Shrubs, bunchgrasses and biological soil crusts (biocrusts) are believed to contribute to site resistance to plant invasions in the presence of cattle grazing. Although fire is a concomitant disturbance with grazing, little is known regarding their combined impacts on invasion resistance. We are the first to date to test the idea that biotic communities mediate the effects of disturbance on site resistance. We assessed cover of Bromus tectorum, shrubs, native bunchgrasses, lichens and mosses in 99 burned and unburned plots located on similar soils where fires occurred between 12 and 23 years before sampling. Structural equation modeling was used to test hypothesized relationships between environmental and disturbance characteristics, the biotic community and resistance to B. tectorum cover. Characteristics of fire and grazing did not directly relate to cover of B. tectorum. Relationships were mediated through shrub, bunchgrass and biocrust communities. Increased site resistance following fire was associated with higher bunchgrass cover and recovery of bunchgrasses and mosses with time since fire. Evidence of grazing was more pronounced on burned sites and was positively correlated with the cover of B. tectorum, indicating an interaction between fire and grazing that decreases site resistance. Lichen cover showed a weak, negative relationship with cover of B. tectorum. Fire reduced near-term site resistance to B. tectorum on actively grazed rangelands. Independent of fire, grazing impacts resulted in reduced site resistance to B. tectorum, suggesting that grazing management that enhances plant and biocrust communities will also enhance site resistance.

A warmer and drier climate in the northern sagebrush biome does not promote cheatgrass invasion or change its response to fire.

PubMed

Larson, Christian D; Lehnhoff, Erik A; Rew, Lisa J

2017-12-01

Dryland shrub communities have been degraded by a range of disturbances and now face additional stress from global climate change. The spring/summer growing season of the North American sagebrush biome is projected to become warmer and drier, which is expected to facilitate the expansion of the invasive annual grass Bromus tectorum (cheatgrass) and alter its response to fire in the northern extent of the biome. We tested these predictions with a factorial experiment with two levels of burning (spring burn and none) and three climate treatments (warming, warming + drying, and control) that was repeated over 3 years in a Montana sagebrush steppe. We expected the climate treatments to make B. tectorum more competitive with the native perennial grass community, especially Pseudoroegneria spicata, and alter its response to fire. Experimental warming and warming + drying reduced B. tectorum cover, biomass, and fecundity, but there was no response to fire except for fecundity, which increased; the native grass community was the most significant factor that affected B. tectorum metrics. The experimental climate treatments also negatively affected P. spicata, total native grass cover, and community biodiversity, while fire negatively affected total native grass cover, particularly when climate conditions were warmer and drier. Our short-term results indicate that without sufficient antecedent moisture and a significant disruption to the native perennial grass community, a change in climate to a warmer and drier spring/summer growing season in the northern sagebrush biome will not facilitate B. tectorum invasion or alter its response to fire.

Reseeding big sagebrush: Techniques and issues

Treesearch

Nancy L. Shaw; Ann M. DeBolt; Roger Rosentreter

2005-01-01

Reestablishing big sagebrush on rangelands now dominated by native perennial grasses, introduced perennial grasses, or exotic annual grasses, particularly cheatgrass (Bromus tectorum), serves to stabilize soil, improve moisture availability and nutrient recyling, increase biological diversity, and foster community stability and resiliency. A first...

Wildlife Habitat Improvement Using Range Improvement Practices

USDA-ARS?s Scientific Manuscript database

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...

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

USDA-ARS?s Scientific Manuscript database

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...

Conservation seeding and diverse seed species performance

USDA-ARS?s Scientific Manuscript database

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...

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

USDA-ARS?s Scientific Manuscript database

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...

The effects of downy brome invasion on mule deer habitat

USDA-ARS?s Scientific Manuscript database

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...

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

Treesearch

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

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...

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

USDA-ARS?s Scientific Manuscript database

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 ...

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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.

Ecosystem impacts of exotic annual invaders in the genus Bromus

Treesearch

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

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...

Assessment of habitat threats to shrublands in the Great Basin: a case study

Treesearch

Mary M. Rowland; Lowell H. Suring; Michael J. Wisdom

2010-01-01

The sagebrush (Artemisia spp.) ecosystem is one of the most imperiled in the United States. In the Great Basin ecoregion and elsewhere, catastrophic wildland fires are often followed by the invasion of cheatgrass (Bromus tectorum L.), eliminating or altering millions of hectares of sagebrush and other shrublands. Sagebrush in...

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

Treesearch

Sheel Bansal; Jeremy J. James; Roger L. Sheley

2014-01-01

Multiple species of annual grasses are invading sagebrush-steppe communities throughout the western United States. Most research has focused on dominant species such as Bromus tectorum (cheatgrass), yet other, less studied annual grasses such as Taeniatherum caput-medusae (medusahead) and Ventenata dubia (ventenata) are spreading rapidly. Future precipitation regimes...

Soil resources influence vegetation and response to fire and fire-surrogate treatments in Sagebrush-Steppe Ecosystems

Treesearch

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

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...

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

Plant guide: Hoary tansyaster (Machaeranthera canescens)

Treesearch

Derek Tilley; Dan Ogle; Loren St. John

2010-01-01

Hoary tansyaster is an early colonizer of rangelands and disturbed sites. It is commonly found on roadsides and gravel pits competing with invasive plants such as cheatgrass (Bromus tectorum) and knapweed species (Centaurea spp). It can be planted to enhance species diversity in rangeland seedings throughout the western United States.

Notice of release of Mountain Home germplasm Sandberg bluegrass (selected germplasm, natural track)

Treesearch

Scott M. Lambert; Stephen B. Monsen; Nancy Shaw

2011-01-01

Mountain Home germplasm Sandberg bluegrass is a small, densely tufted short-lived perennial bunchgrass adapted to low elevation, semi-arid sites with long, hot growing seasons. Mountain Home's drought tolerance, competitive nature, and ease of establishment make it an excellent choice for post-fire restoration of cheatgrass (Bromus tectorum L.) dominated...

20 Years of natural recovery after wildfire on northern Nevada rangelands

Treesearch

Ann P. Bollinger; Barry L. Perryman

2008-01-01

In recent decades Northern Nevada has experienced a dramatic increase in cheatgrass (Bromus tectorum). As a result, wildfire frequency and size has increased. The objective of this project was to examine natural vegetation recovery and trend following 1985 wildfires. Density and cover measurements determined a high but fluctuating occurrence of...

The importance of persistent monitoring of great basin rangeland rehabilitation efforts

USDA-ARS?s Scientific Manuscript database

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...

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.

Pyrenophoric acid, a phytotoxic sesquiterpenoid penta-2,4-dienoic acid produced by a potential mycoherbicide, Pyrenophora semeniperda

Treesearch

Marco Masi; Susan Meyer; Alessio Cimmino; Anna Andolfi; Antonio Evidente

2014-01-01

A new phytotoxic sesquiterpenoid penta-2,4- dienoic acid, named pyrenophoric acid, was isolated from solid wheat seed culture of Pyrenophora semeniperda, a fungal pathogen proposed as a mycoherbicide for biocontrol of cheatgrass (Bromus tectorum) and other annual bromes. These bromes are serious weeds in winter cereals and also on temperate semiarid rangelands....

Vegetation of chained and non-chained seedings after wildfire in Utah

Treesearch

Jeffrey E. Ott; E. Durant McArthur; Bruce A. Roundy

2003-01-01

After wildfires in 1996 in the sagebrush(Artemisias pp.) and pinyon-juniper (Pinus spp.-Juniperus spp.) zones of west-central Utah, the USDI-BLM attempted to reduce soil erosion and cheatgrass proliferation (Bromus tectorum L.) through rehabilitation treatments. We compared the vegetation of aerially seeded, chained treatments with aerially seeded but non-chained...

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

Treating downy brome with herbicide and seeding with native shrubs

Treesearch

Suzanne Owen; Carolyn Sieg

2011-01-01

Downy brome or cheatgrass (Bromus tectorum L.) is one of the most invasive and widespread exotic plants in North America. Downy brome can reduce soil nutrient availability, alter native plant community composition, and increase fire frequencies. The effectiveness of Plateau® imazapic herbicide in reducing downy brome cover has been variable, and there is uncertainty...

Soil moisture and biogeochemical factors influence the distribution of annual Bromus species

USGS Publications Warehouse

Belnap, Jayne; Stark, John Thomas; Rau, Benjamin; Allen, Edith B.; Phillips, Sue

2016-01-01

Abiotic factors have a strong influence on where annual Bromus species are found. At the large regional scale, temperature and precipitation extremes determine the boundaries of Bromusoccurrence. At the more local scale, soil characteristics and climate influence distribution, cover, and performance. In hot, dry, summer-rainfall-dominated deserts (Sonoran, Chihuahuan), little or noBromus is found, likely due to timing or amount of soil moisture relative to Bromus phenology. In hot, winter-rainfall-dominated deserts (parts of the Mojave Desert), Bromus rubens is widespread and correlated with high phosphorus availability. It also responds positively to additions of nitrogen alone or with phosphorus. On the Colorado Plateau, with higher soil moisture availability, factors limiting Bromus tectorum populations vary with life stage: phosphorus and water limit germination, potassium and the potassium/magnesium ratio affect winter performance, and water and potassium/magnesium affect spring performance. Controlling nutrients also change with elevation. In cooler deserts with winter precipitation (Great Basin, Columbia Plateau) and thus even greater soil moisture availability, B. tectorum populations are controlled by nitrogen, phosphorus, or potassium. Experimental nitrogen additions stimulate Bromus performance. The reason for different nutrients limiting in dissimilar climatic regions is not known, but it is likely that site conditions such as soil texture (as it affects water and nutrient availability), organic matter, and/or chemistry interact in a manner that regulates nutrient availability and limitations. Under future drier, hotter conditions,Bromus distribution is likely to change due to changes in the interaction between moisture and nutrient availability.

Is Pyrenophora semeniperda the cause of downy brome (Bromus tectorum) die-offs?

Treesearch

Owen W. Baughman; Susan E. Meyer

2013-01-01

Downy brome (cheatgrass) is a highly successful, exotic, winter annual invader in semi-arid western North America, forming near-monocultures across many landscapes. A frequent but poorly understood phenomenon in these heavily invaded areas is periodic 'die-off' or complete stand failure. The fungal pathogen Pyrenophora semeniperda is abundant in cheatgrass...

Cheating cheatgrass: New research to combat a wily invasive weed

Treesearch

Gail Wells

2012-01-01

Cheatgrass and its cousin, red brome, are exotic annual grasses that have invaded and altered ecosystem dynamics in more than 41 million acres of desert shrublands between the Rockies and the Cascade-Sierra chain. A fungus naturally associated with these Bromus species has been found lethal to the plants' soil-banked dormant seeds. Supported by the Joint Fire...

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

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 thenmore » 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.« less

Controlling cheatgrass in winter range to restore habitat and endemic fire

Treesearch

Jennifer L. Vollmer; Joseph G. Vollmer

2008-01-01

Habitat managers can better prepare a program for prescribed burns, wildfire management, and maximum forage biomass by understanding the response of key shrubs to the tools utilized to reduce cheatgrass (Bromus spp.) competition. Application of Plateau® herbicide, prior to annual brome germination, at rates up to 8 oz/acre with or without surfactant...

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.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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 tomore » the superior competitive ability of cheatgrass in Washington.« less

Cheatgrass encroachment on a ponderosa pine ecological restoration project in northern Arizona, U. S. A.

Treesearch

Christopher M. McGlone; Judith D. Springer; W. Wallace Covington

2008-01-01

(Please note, this is an abstract only) Land managers frequently thin small-diameter trees and apply prescribed fire to reduce fuel loads and restore ecosystem structure, function, and process in forested areas. There is increasing concern that disturbances associated with these management practices can facilitate nonnative plant invasions. Bromus tectorum is an annual...

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.

What makes Great Basin sagebrush ecosystems invasible by Bromus tectorum?

Treesearch

Jeanne C. Chambers; Bruce A. Roundy; Robert R. Blank; Susan E. Meyer; A. Whittaker

2007-01-01

Ecosystem susceptibility to invasion by nonnative species is poorly understood, but evidence is increasing that spatial and temporal variability in resources has large-scale effects. We conducted a study in Artemisia tridentata ecosystems at two Great Basin locations examining differences in resource availability and invasibility of Bromus...

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

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.

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

Characterizing the landscape dynamics of an invasive plant and risk of invasion using remote sensing.

PubMed

Bradley, Bethany A; Mustard, John F

2006-06-01

Improved understanding of the spatial dynamics of invasive plant species may lead to more effective land management and reduced future invasion. Here, we identified the spatial extents of nonnative cheatgrass (Bromus tectorum) in the north central Great Basin using remotely sensed data from Landsat MSS, TM, and ETM+. We compared cheatgrass extents in 1973 and 2001 to six spatially explicit landscape variables: elevation, aspect, hydrographic channels, cultivation, roads, and power lines. In 2001, Cheatgrass was 10% more likely to be found in elevation ranges from 1400 to 1700 m (although the data suggest a preferential invasion into lower elevations by 2001), 6% more likely on west and northwest facing slopes, and 3% more likely within hydrographic channels. Over this time period, cheatgrass expansion was also closely linked to proximity to land use. In 2001, cheatgrass was 20% more likely to be found within 3 km of cultivation, 13% more likely to be found within 700 m of a road, and 15% more likely to be found within 1 km of a power line. Finally, in 2001 cheatgrass was 26% more likely to be present within 150 m of areas occupied by cheatgrass in 1973. Using these relationships, we created a risk map of future cheatgrass invasion that may aid land management. These results highlight the importance of including land use variables and the extents of current plant invasion in predictions of future risk.

Indirect effects of an invasive annual grass on seed fates of two native perennial grass species.

PubMed

Meyer, Susan E; Merrill, Katherine T; Allen, Phil S; Beckstead, Julie; Norte, Anna S

2014-04-01

Invasive plants exhibit both direct and indirect negative effects on recruitment of natives following invasion. We examined indirect effects of the invader Bromus tectorum (cheatgrass) on seed fates of two native grass species, Elymus elymoides and Pseudoroegneria spicata, by removing B. tectorum and by adding inoculum of the shared seed pathogen Pyrenophora semeniperda in factorial experiments at xeric and mesic field sites. We also included a supplemental watering treatment to increase emergence and also the potential for pathogen escape. We recorded emergence and survival of native seedlings and also determined the fate of unemerged seeds. At the xeric site, Pyrenophora-caused mortality was high (34%), and effects of other pathogens and failed emergence of germinants were smaller. Cheatgrass removal negatively affected both emergence (35 vs. 25%) and spring survival (69 vs. 42%). Pyrenophora-caused seed mortality increased with inoculum augmentation for both species (22 vs. 47% overall), but emergence was negatively impacted only for P. spicata (20 vs. 34%). At the mesic site, Pyrenophora-caused mortality was low (6%). Cheatgrass removal doubled emergence (26 vs. 14%). Seed mortality increased significantly with inoculum augmentation for P. spicata (12 vs. 5%) but not E. elymoides, while emergence was not significantly affected in either species. A large fraction of seeds produced germinants that failed to emerge (37%), while another large fraction (35%) was killed by other pathogens. We conclude that facilitation by cheatgrass at the xeric site but interference at the mesic site was probably mediated through litter effects that could be ameliorative or suppressive. Apparent competition between cheatgrass and native grasses could occur through Pyrenophora, especially in a xeric environment, but effects were weak or absent at emergence. This was probably because Pyrenophora attacks the same slow-germinating fraction that is subject to pre-emergence mortality from

Population genetic structure of Bromus tectorum in the mountains of western North America

Treesearch

Spencer Arnesen; Craig E. Coleman; Susan E. Meyer

2017-01-01

PREMISE OF THE STUDY: Invasive species are often initially restricted to a narrow range and may then expand through any of multiple mechanisms including phenotypic plasticity, in situ evolution, or selection on traits preadapted for new habitats. Our study used population genetics to explore possible processes by which the highly selfing invasive annual grass Bromus...

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

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

Investing in rangeland restoration in the Arid West, USA: countering the effects of an invasive weed on the long-term fire cycle.

PubMed

Epanchin-Niell, Rebecca; Englin, Jeffrey; Nalle, Darek

2009-01-01

In large areas of the arid western United States, much of which are federally managed, fire frequencies and associated management costs are escalating as flammable, invasive cheatgrass (Bromus tectorum) increases its stronghold. Cheatgrass invasion and the subsequent increase in fire frequency result in the loss of native vegetation, less predictable forage availability for livestock and wildlife, and increased costs and risk associated with firefighting. Revegetation following fire on land that is partially invaded by cheatgrass can reduce both the dominance of cheatgrass and its associated high fire rate. Thus restoration can be viewed as an investment in fire-prevention and, if native seed is used, an investment in maintaining native vegetation on the landscape. Here we develop and employ a Markov model of vegetation dynamics for the sagebrush steppe ecosystem to predict vegetation change and management costs under different intensities and types of post-fire revegetation. We use the results to estimate the minimum total cost curves for maintaining native vegetation on the landscape and for preventing cheatgrass dominance. Our results show that across a variety of model parameter possibilities, increased investment in post-fire revegetation reduces long-term fire management costs by more than enough to offset the costs of revegetation. These results support that a policy of intensive post-fire revegetation will reduce long-term management costs for this ecosystem, in addition to providing environmental benefits. This information may help justify costs associated with revegetation and raise the priority of restoration in federal land budgets.

Vegetation response to fire and postburn seeding treatments in juniper woodlands of the Grand Staircase-Escalante National Monument, Utah

USGS Publications Warehouse

Evangelista, P.; Stohlgren, T.J.; Guenther, D.; Stewart, S.

2004-01-01

We compared 3 naturally ignited burns with unburned sites in the Grand Staircase-Escalante National Monument. Each burn site was restored with native and nonnative seed mixes, restored with native seeds only, or regenerated naturally. In general, burned sites had significantly lower native species richness (1.8 vs. 2.9 species), native species cover (11% vs. 22.5%), and soil crust cover (4.1% vs. 15%) than unburned sites. Most burned plots, seeded or not, had significantly higher average nonnative species richness and cover and lower average native species richness and cover than unburned sites. Regression tree analyses suggest site variation was equally important to rehabilitation results as seeding treatments. Low native species richness and cover, high soil C, and low cover of biological soil crusts may facilitate increased nonnative species richness and cover. Our study also found that unburned sites in the region had equally high cover of nonnative species compared with the rest of the Monument. Cheatgrass (Bromus tectorum) dominated both burned and unburned sites. Despite the invasion of cheatgrass, unburned sites still maintain higher native species richness; however, the high cover of cheatgrass may increase fire frequency, further reduce native species richness and cover, and ultimately change vegetation composition in juniper woodlands.

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.

Identification of the infection route of a Fusarium seed pathogen into nondormant Bromus tectorum seeds

Treesearch

JanaLynn Franke; Brad Geary; Susan E. Meyer

2014-01-01

The genus Fusarium has a wide host range and causes many different forms of plant disease. These include seed rot and seedling blight diseases of cultivated plants. The diseases caused by Fusarium on wild plants are less well-known. In this study, we examined disease development caused by Fusarium sp. n on nondormant seeds of the important rangeland weed Bromus...

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).

When perception reflects reality: Non-native grass invasion alters small mammal risk landscapes and survival

USGS Publications Warehouse

Ceradnini, Joseph P.; Chalfoun, Anna D.

2017-01-01

Modification of habitat structure due to invasive plants can alter the risk landscape for wildlife by, for example, changing the quality or availability of refuge habitat. Whether perceived risk corresponds with actual fitness outcomes, however, remains an important open question. We simultaneously measured how habitat changes due to a common invasive grass (cheatgrass, Bromus tectorum) affected the perceived risk, habitat selection, and apparent survival of a small mammal, enabling us to assess how well perceived risk influenced important behaviors and reflected actual risk. We measured perceived risk by nocturnal rodents using a giving-up density foraging experiment with paired shrub (safe) and open (risky) foraging trays in cheatgrass and native habitats. We also evaluated microhabitat selection across a cheatgrass gradient as an additional assay of perceived risk and behavioral responses for deer mice (Peromyscus maniculatus) at two spatial scales of habitat availability. Finally, we used mark-recapture analysis to quantify deer mouse apparent survival across a cheatgrass gradient while accounting for detection probability and other habitat features. In the foraging experiment, shrubs were more important as protective cover in cheatgrass-dominated habitats, suggesting that cheatgrass increased perceived predation risk. Additionally, deer mice avoided cheatgrass and selected shrubs, and marginally avoided native grass, at two spatial scales. Deer mouse apparent survival varied with a cheatgrass–shrub interaction, corresponding with our foraging experiment results, and providing a rare example of a native plant mediating the effects of an invasive plant on wildlife. By synthesizing the results of three individual lines of evidence (foraging behavior, habitat selection, and apparent survival), we provide a rare example of linkage between behavioral responses of animals indicative of perceived predation risk and actual fitness outcomes. Moreover, our results

Cheatgrass Dead Zones in Northern Nevada

USDA-ARS?s Scientific Manuscript database

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...

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nancy F. Glenn; Jessica J. Mitchell; Matthew O. Anderson

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 shouldmore » 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).« less

Species' traits help predict small mammal responses to habitat homogenization by an invasive grass.

PubMed

Ceradini, Joseph P; Chalfoun, Anna D

2017-07-01

Invasive plants can negatively affect native species, however, the strength, direction, and shape of responses may vary depending on the type of habitat alteration and the natural history of native species. To prioritize conservation of vulnerable species, it is therefore critical to effectively predict species' responses to invasive plants, which may be facilitated by a framework based on species' traits. We studied the population and community responses of small mammals and changes in habitat heterogeneity across a gradient of cheatgrass (Bromus tectorum) cover, a widespread invasive plant in North America. We live-trapped small mammals over two summers and assessed the effect of cheatgrass on native small mammal abundance, richness, and species-specific and trait-based occupancy, while accounting for detection probability and other key habitat elements. Abundance was only estimated for the most common species, deer mice (Peromyscus maniculatus). All species were pooled for the trait-based occupancy analysis to quantify the ability of small mammal traits (habitat association, mode of locomotion, and diet) to predict responses to cheatgrass invasion. Habitat heterogeneity decreased with cheatgrass cover. Deer mouse abundance increased marginally with cheatgrass. Species richness did not vary with cheatgrass, however, pocket mouse (Perognathus spp.) and harvest mouse (Reithrodontomys spp.) occupancy tended to decrease and increase, respectively, with cheatgrass cover, suggesting a shift in community composition. Cheatgrass had little effect on occupancy for deer mice, 13-lined ground squirrels (Spermophilus tridecemlineatus), and Ord's kangaroo rat (Dipodomys ordii). Species' responses to cheatgrass primarily corresponded with our a priori predictions based on species' traits. The probability of occupancy varied significantly with a species' habitat association but not with diet or mode of locomotion. When considered within the context of a rapid habitat change

Species’ traits help predict small mammal responses to habitat homogenization by an invasive grass

USGS Publications Warehouse

Ceradini, Joseph P.; Chalfoun, Anna D.

2017-01-01

Invasive plants can negatively affect native species, however, the strength, direction, and shape of responses may vary depending on the type of habitat alteration and the natural history of native species. To prioritize conservation of vulnerable species, it is therefore critical to effectively predict species’ responses to invasive plants, which may be facilitated by a framework based on species’ traits. We studied the population and community responses of small mammals and changes in habitat heterogeneity across a gradient of cheatgrass (Bromus tectorum) cover, a widespread invasive plant in North America. We live-trapped small mammals over two summers and assessed the effect of cheatgrass on native small mammal abundance, richness, and species-specific and trait-based occupancy, while accounting for detection probability and other key habitat elements. Abundance was only estimated for the most common species, deer mice (Peromyscus maniculatus). All species were pooled for the trait-based occupancy analysis to quantify the ability of small mammal traits (habitat association, mode of locomotion, and diet) to predict responses to cheatgrass invasion. Habitat heterogeneity decreased with cheatgrass cover. Deer mouse abundance increased marginally with cheatgrass. Species richness did not vary with cheatgrass, however, pocket mouse (Perognathus spp.) and harvest mouse (Reithrodontomys spp.) occupancy tended to decrease and increase, respectively, with cheatgrass cover, suggesting a shift in community composition. Cheatgrass had little effect on occupancy for deer mice, 13-lined ground squirrels (Spermophilus tridecemlineatus), and Ord's kangaroo rat (Dipodomys ordii). Species’ responses to cheatgrass primarily corresponded with our a priori predictions based on species’ traits. The probability of occupancy varied significantly with a species’ habitat association but not with diet or mode of locomotion. When considered within the context of a rapid

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.

Plant community resistance to invasion by Bromus species: The roles of community attributes, Bromus interactions with plant communities, and Bromus traits [Chapter 10

Treesearch

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

2016-01-01

The factors that determine plant community resistance to exotic annual Bromus species (Bromus hereafter) 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...

Impact of native grasses and cheatgrass (Bromus tectorum) on Great Basin forb seedling growth

Treesearch

Hilary Parkinson; Cathy Zabinski; Nancy Shaw

2013-01-01

Re-establishing native communities that resist exotic weed invasion and provide diverse habitat for wildlife are high priorities for restoration in sagebrush ecosystems. Native forbs are an important component of healthy rangelands in this system, but they are rarely included in seedings. Understanding competitive interactions between forb and grass seedlings is...

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.

Rehabilitation of cheatgrass-infested rangelands: management

USDA-ARS?s Scientific Manuscript database

This is the final part of a three part series specifically addressing lessons learned concerning the management of rehabilitated cheatgrass-infested rangelands. Steve Novak and Richard Mack reported in 2003 that they found no evidence of outcrossing in 2,000 cheatgrass seedlings from 60 North Americ...

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

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.

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

USDA-ARS?s Scientific Manuscript database

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 ...

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

Treesearch

Rachel O. Jones; Jeanne C. Chambers; David I. Board; Dale W. Johnson; Robert R. Blank

2015-01-01

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 establishment of native perennials. We developed a multivariate...

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.

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

USDA-ARS?s Scientific Manuscript database

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...

Suppression of cheatgrass by established perennial grasses: I. mechanisms

USDA-ARS?s Scientific Manuscript database

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...

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.

Yield responses of ruderal plants to sucrose in invasive-dominated sagebrush steppe of the northern Great Basin

USGS Publications Warehouse

Brunson, Jessi; Pyke, David A.; Perakis, Steven 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.

Established native perennial grasses out-compete an invasive annual grass regardless of soil water and nutrient availability

Treesearch

Christopher M. McGlone; Carolyn Hull Sieg; Thomas E. Kolb; Ty Nietupsky

2012-01-01

Competition and resource availability influence invasions into native perennial grasslands by nonnative annual grasses such as Bromus tectorum. In two greenhouse experiments we examined the influence of competition, water availability, and elevated nitrogen (N) and phosphorus (P) availability on growth and reproduction of the invasive annual grass B. tectorum and two...

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.

Introduction: Exotic Annual Bromus in the Western USA

USGS Publications Warehouse

Germino, Matthew; Chambers, Jeanne C.; Brown, Cynthia S.

2016-01-01

The spread and impacts of exotic species are unambiguous, global threats to many ecosystems. A prominent example is the suite of annual grasses in the Bromus genus (Bromus hereafter) that originate from Europe and Eurasia but have invaded or are invading large areas of the Western USA. This book brings a diverse, multidisciplinary group of authors together to synthesize current knowledge, research needs, and management implications for Bromus. Exotic plant invasions are multifaceted problems, and understanding and managing them requires the biological, ecological, sociological, and economic perspectives that are integrated in this book. Knowing how well information from one geographic or environmental setting can transfer to another is a key need for broadly distributed Bromus species especially given ongoing climate change. Thus, the chapters in the book compare and contrast invasibility of different ecoregions and invasiveness of different Bromus species. A universal theme is managing for ecosystems that are resilient to disturbance and resistant to invasion which will be essential for adaptation to the human-caused problem of Bromus in the Western USA.

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

Treesearch

Rachel Jones; Jeanne C. Chambers; Dale W. Johnson; Robert R. Blank; David I. Board

2015-01-01

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 study, we examined effects of repeated burning, litter removal, and post-fire seeding on...

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.

Plant invaders, global change and landscape restoration

USGS Publications Warehouse

Pyke, D.A.; Knick, S.T.

2005-01-01

Modifications in land uses, technology, transportation and biogeochemical cycles currently influence the spread of organisms by reducing the barriers that once restricted their movements. We provide an overview of the spatial and temporal extent for agents of environmental change (land and disturbance transformations, biogeochemical modifications, biotic additions and losses) and highlight those that strongly influence rangeland ecosystems. Restoration may provide a mechanism for ameliorating the impacts of invasive species, but applications of restoration practices over large scales, e.g. ecoregions, will yield benefits earlier when the landscape is prioritised by criteria that identify locations where critical restoration species can grow and where success will be high. We used the Great Basin, USA as our region of interest where the invasive annual grass, cheatgrass (Bromus tectorum), dominates millions of hectares. A landscape-level restoration model for sagebrush (Artemisia tridentata ssp. tridentata and ssp. wyomingensis) was developed to meet the goal of establishing priority habitat for wildlife. This approach could be used in long-range planning of rangeland ecosystems where funds and labour for restoration projects may vary annually. Copyright ?? NISC Pty Ltd.

Using multi-date satellite imagery to monitor invasive grass species distribution in post-wildfire landscapes: An iterative, adaptable approach that employs open-source data and software

USGS Publications Warehouse

West, Amanda M.; Evangelista, Paul H.; Jarnevich, Catherine S.; Kumar, Sunil; Swallow, Aaron; Luizza, Matthew; Chignell, Steve

2017-01-01

Among the most pressing concerns of land managers in post-wildfire landscapes are the establishment and spread of invasive species. Land managers need accurate maps of invasive species cover for targeted management post-disturbance that are easily transferable across space and time. In this study, we sought to develop an iterative, replicable methodology based on limited invasive species occurrence data, freely available remotely sensed data, and open source software to predict the distribution of Bromus tectorum (cheatgrass) in a post-wildfire landscape. We developed four species distribution models using eight spectral indices derived from five months of Landsat 8 Operational Land Imager (OLI) data in 2014. These months corresponded to both cheatgrass growing period and time of field data collection in the study area. The four models were improved using an iterative approach in which a threshold for cover was established, and all models had high sensitivity values when tested on an independent dataset. We also quantified the area at highest risk for invasion in future seasons given 2014 distribution, topographic covariates, and seed dispersal limitations. These models demonstrate the effectiveness of using derived multi-date spectral indices as proxies for species occurrence on the landscape, the importance of selecting thresholds for invasive species cover to evaluate ecological risk in species distribution models, and the applicability of Landsat 8 OLI and the Software for Assisted Habitat Modeling for targeted invasive species management.

Using multi-date satellite imagery to monitor invasive grass species distribution in post-wildfire landscapes: An iterative, adaptable approach that employs open-source data and software

NASA Astrophysics Data System (ADS)

West, Amanda M.; Evangelista, Paul H.; Jarnevich, Catherine S.; Kumar, Sunil; Swallow, Aaron; Luizza, Matthew W.; Chignell, Stephen M.

2017-07-01

Among the most pressing concerns of land managers in post-wildfire landscapes are the establishment and spread of invasive species. Land managers need accurate maps of invasive species cover for targeted management post-disturbance that are easily transferable across space and time. In this study, we sought to develop an iterative, replicable methodology based on limited invasive species occurrence data, freely available remotely sensed data, and open source software to predict the distribution of Bromus tectorum (cheatgrass) in a post-wildfire landscape. We developed four species distribution models using eight spectral indices derived from five months of Landsat 8 Operational Land Imager (OLI) data in 2014. These months corresponded to both cheatgrass growing period and time of field data collection in the study area. The four models were improved using an iterative approach in which a threshold for cover was established, and all models had high sensitivity values when tested on an independent dataset. We also quantified the area at highest risk for invasion in future seasons given 2014 distribution, topographic covariates, and seed dispersal limitations. These models demonstrate the effectiveness of using derived multi-date spectral indices as proxies for species occurrence on the landscape, the importance of selecting thresholds for invasive species cover to evaluate ecological risk in species distribution models, and the applicability of Landsat 8 OLI and the Software for Assisted Habitat Modeling for targeted invasive species management.

Land uses, fire, and invasion: Exotic annual Bromus and human dimensions

USGS Publications Warehouse

Pyke, David A.; Chambers, Jeanne C.; Beck, Jeffrey L.; Brooks, Matthew L.; Mealor, Brian A.

2016-01-01

Human land uses are the primary cause of the introduction and spread of exotic annual Bromusspecies. Initial introductions were likely linked to contaminated seeds used by homesteading farmers in the late 1880s and early 1900s. Transportation routes aided their spread. Unrestricted livestock grazing from the 1800s through the mid-1900s reduced native plant competitors leaving large areas vulnerable to Bromus dominance. Ecosystems with cooler and moister soils tend to have greater potential to recover from disturbances (resilience) and to be more resistant to Bromusinvasion and dominance. Warmer and drier ecosystems are less resistant to Bromus and are threatened by altered fire regimes which can lead to Bromus dominance, impacts to wildlife, and alternative stable states. Native Americans used fire for manipulating plant communities and may have contributed to the early dominance of Bromus in portions of California. Fire as a tool is now limited to site preparation for revegetation in most ecosystems where Bromus is a significant problem. Once Bromus dominates, breaking annual grass/fire cycles requires restoring fire-tolerant perennial grasses and forbs, which can compete with Bromus and resist its dominance. Current weed management policies often lack regulations to prevent further expansion of Bromus. Research is needed on how and where livestock grazing might help increase perennial grass and forb cover and density to create ecosystems that are more resistant to Bromus. Also, studies are needed to ascertain the role, if any, of oil and gas development in contributing to the spread of Bromus.

Allometry of root branching and its relationship to root morphological and functional traits in three range grasses.

PubMed

Arredondo, J Tulio; Johnson, Douglas A

2011-11-01

The study of proportional relationships between size, shape, and function of part of or the whole organism is traditionally known as allometry. Examination of correlative changes in the size of interbranch distances (IBDs) at different root orders may help to identify root branching rules. Root morphological and functional characteristics in three range grasses {bluebunch wheatgrass [Pseudoroegneria spicata (Pursh) Löve], crested wheatgrass [Agropyron desertorum (Fisch. ex Link) Schult.×A. cristatum (L.) Gaert.], and cheatgrass (Bromus tectorum L.)} were examined in response to a soil nutrient gradient. Interbranch distances along the main root axis and the first-order laterals as well as other morphological and allocation root traits were determined. A model of nutrient diffusivity parameterized with root length and root diameter for the three grasses was used to estimate root functional properties (exploitation efficiency and exploitation potential). The results showed a significant negative allometric relationship between the main root axis and first-order lateral IBD (P ≤ 0.05), but only for bluebunch wheatgrass. The main root axis IBD was positively related to the number and length of roots, estimated exploitation efficiency of second-order roots, and specific root length, and was negatively related to estimated exploitation potential of first-order roots. Conversely, crested wheatgrass and cheatgrass, which rely mainly on root proliferation responses, exhibited fewer allometric relationships. Thus, the results suggested that species such as bluebunch wheatgrass, which display slow root growth and architectural root plasticity rather than opportunistic root proliferation and rapid growth, exhibit correlative allometry between the main axis IBD and morphological, allocation, and functional traits of roots.

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.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hinds, N R; Rogers, L E

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 themore » 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.« less

Sagebrush Ecosystems Under Fire

DOE Office of Scientific and Technical Information (OSTI.GOV)

Downs, Janelle L.

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 annualsmore » 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.« less

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.

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

Timing of grazing to reduce cheatgrass fuels

USDA-ARS?s Scientific Manuscript database

The introduction and subsequent invasion of cheatgrass onto millions of acres of Great Basin rangelands has revolutionized secondary succession by providing a fine-textured early maturing fuel that has increased the chance, rate, spread and season of wildfires. With such vast acreages of landscapes ...

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

USDA-ARS?s Scientific Manuscript database

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...

Re-seeding research will help in cheatgrass battle

USGS Publications Warehouse

Allen, Craig D.

2006-01-01

Funding from the National Interagency Fire Center’s Joint Fire Science Program is helping researchers in northwestern Arizona determine whether several native grasses can be used to battle invasive cheatgrass following fire in ponderosa pine ecosystems.

Karyotype characterization and comparison of three hexaploid species of Bromus Linnaeus, 1753 (Poaceae)

PubMed Central

Artico, Leonardo Luís; Mazzocato, Ana Cristina; Ferreira, Juliano Lino; Carvalho, Carlos Roberto; Clarindo, Wellington Ronildo

2017-01-01

Abstract Chromosome morphometry and nuclear DNA content are useful data for cytotaxonomy and to understand the evolutionary history of different taxa. For the genus Bromus Linnaeus, 1753, distinct ploidy levels have been reported, occurring from diploid to duodecaploid species. The geographic distribution of Bromus species has been correlated with chromosome number and ploidy level. In this study, the aims were to determine the nuclear genome size and characterize the karyotype of the South American Bromus species: Bromus auleticus Trinius ex Nees, 1829, Bromus brachyanthera Döll, 1878 and Bromus catharticus Vahl, 1791. The mean nuclear 2C value ranged from 2C = 12.64 pg for B. catharticus to 2C = 17.92 pg for B. auleticus, meaning a maximum variation of 2C = 5.28 pg, equivalent to 41.70%. Despite this significant difference in 2C value, the three species exhibit the same chromosome number, 2n = 6x = 42, which confirms their hexaploid origin. Corroborating the genome size, the chromosome morphometry (total, short- and long-arm length) and, consequently, the class differed among the karyotypes of the species. Based on the first karyograms for these Bromus species, some morphologically similar and several distinct chromosome pairs were found. Therefore, the karyotype characterization confirmed the hexaploid origin of the studied Bromus species, which differ in relation to the karyogram and the nuclear 2C value. Considering this, cytogenetics and flow cytometry can be used to discriminate Bromus species, contributing to taxonomy and systematic studies and providing information on the evolutionary history of this taxa. PMID:28919960

Karyotype characterization and comparison of three hexaploid species of Bromus Linnaeus, 1753 (Poaceae).

PubMed

Artico, Leonardo Luís; Mazzocato, Ana Cristina; Ferreira, Juliano Lino; Carvalho, Carlos Roberto; Clarindo, Wellington Ronildo

2017-01-01

Chromosome morphometry and nuclear DNA content are useful data for cytotaxonomy and to understand the evolutionary history of different taxa. For the genus Bromus Linnaeus, 1753, distinct ploidy levels have been reported, occurring from diploid to duodecaploid species. The geographic distribution of Bromus species has been correlated with chromosome number and ploidy level. In this study, the aims were to determine the nuclear genome size and characterize the karyotype of the South American Bromus species: Bromus auleticus Trinius ex Nees, 1829, Bromus brachyanthera Döll, 1878 and Bromus catharticus Vahl, 1791. The mean nuclear 2C value ranged from 2C = 12.64 pg for B. catharticus to 2C = 17.92 pg for B. auleticus , meaning a maximum variation of 2C = 5.28 pg, equivalent to 41.70%. Despite this significant difference in 2C value, the three species exhibit the same chromosome number, 2n = 6x = 42, which confirms their hexaploid origin. Corroborating the genome size, the chromosome morphometry (total, short- and long-arm length) and, consequently, the class differed among the karyotypes of the species. Based on the first karyograms for these Bromus species, some morphologically similar and several distinct chromosome pairs were found. Therefore, the karyotype characterization confirmed the hexaploid origin of the studied Bromus species, which differ in relation to the karyogram and the nuclear 2C value. Considering this, cytogenetics and flow cytometry can be used to discriminate Bromus species, contributing to taxonomy and systematic studies and providing information on the evolutionary history of this taxa.

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

USDA-ARS?s Scientific Manuscript database

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...

Seed harvesting is influenced by associational effects in mixed seed neighbourhoods, not just by seed density

USGS Publications Warehouse

Ostoja, Steven M.; Schupp, Eugene W.; Durham, Susan; Klinger, Robert C.

2013-01-01

Rodents frequently forage in a density-dependent manner, increasing harvesting in patches with greater seed densities. Although seldom considered, seed harvesting may also depend on the species identities of other individuals in the seed neighbourhood. When the seed harvest of a focal species increases in association with another seed species, the focal species suffers from Associational Susceptibility. In contrast, if seeds of the focal species are harvested less when in association with a second species, the focal species benefits from Associational Resistance.To evaluate density dependence and associational effects among seeds in mixtures, we conducted seed removal experiments using a completely additive design patterned after a two-species competition experiment using seeds of either Achnatherum hymenoides(Indian ricegrass), Leymus cinereus (basin wildrye) or Pseudoroegneria spicata (bluebunch wheatgrass), all native perennial grasses, combined with seeds of Bromus tectorum(cheatgrass), a non-native annual grass. The experiment involved placing five fixed quantities of the native seeds mixed with five fixed quantities of B. tectorum seeds in a factorial design, resulting in 35 seed mixture combinations. The seed-eating rodent community at our study sites, in order of abundance, is composed of Peromyscus maniculatus (North American deer mouse), Dipodomys ordii (Ord's kangaroo rat) and Perognathus parvus (Great Basin pocket mouse).Native seed harvesting was density dependent, with a greater proportion of seeds being harvested as density increased. In the mixed density model, the presence of B. tectorumdid not affect harvest of any of the native species' seeds when analysed individually. However, when all three native species were analysed together, increasing quantities of B. tectorum resulted in reduced harvest of native seeds, demonstrating weak but significant Associational Resistance. In contrast, harvest of B. tectorum seeds increased

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

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 themore » 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.« less

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

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

USDA-ARS?s Scientific Manuscript database

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...

Introduction: Exotic annual Bromus in the western USA [Chapter 1

Treesearch

Matthew J. Germino; Jeanne C. Chambers; Cynthia S. Brown

2016-01-01

The spread and impacts of exotic species are unambiguous, global threats to many ecosystems. A prominent example is the suite of annual grasses in the Bromus genus (Bromus hereafter) that originate from Europe and Eurasia but have invaded or are invading large areas of the Western USA. This book brings a diverse, multidisciplinary group of authors together to...

Establishing Wyoming big sagebrush in annual brome-invaded landscapes with seeding and herbicides

USDA-ARS?s Scientific Manuscript database

Restoring degraded grasslands with seeding is a major challenge. Often, seeded species do not establish and areas become/remain dominated by unwanted plants. We combined herbicides and reseeding in former coal mining fields dominated by exotic winter annual grasses [downy brome (Bromus tectorum[L....

Competition for soil nitrate and invasive weed resistance of three shrub-steppe growth forms

Treesearch

Eamonn D. Leonard

2007-01-01

Determining mechanisms responsible for weed resistance and invasion success are two issues that have potential in aiding successful land management decisions. The first experiment evaluates the competitive effects of an invasive annual grass downy brome (Bromus tectorum L.), an invasive biennial forb dyer's woad (Isatis tinctoria...

The importance of education in managing invasive plant species

USDA-ARS?s Scientific Manuscript database

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...

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.

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

Hydrologic Vulnerability and Risk Assessment Associated With the Increased Role of Fire on Western Landscapes, Great Basin, USA

NASA Astrophysics Data System (ADS)

Williams, C. J.; Pierson, F. B.; Robichaud, P. R.; Spaeth, K. E.; Hardegree, S. P.; Clark, P. E.; Moffet, C. A.; Al-Hamdan, O. Z.; Boll, J.

2010-12-01

Landscape-scale plant community transitions and altered fire regimes across Great Basin, USA, rangelands have increased the likelihood of post-fire flooding and erosion events. These hazards are particularly concerning for western urban centers along the rangeland urban-wildland interface where natural resources, property, and human life are at risk. Extensive conversion of 4-7 million hectares of Great Basin shrub-steppe to cheatgrass-dominated (Bromus tectorum) grasslands has increased the frequency and size of wildland fires within these ecosystems. Fire frequencies have increased by more than an order of magnitude and occur on 3-10 year intervals across much of the cheatgrass-dominated landscape. Extensive tree (Pinus spp. and Juniperus spp.) encroachment into wooded shrub-steppe has increased heavy fuel loads. Ladder fuels in these ecosystems promote rapidly spreading, high-intensity and severe ground-surface-crown fires. These altered fuel structures across much of the historical Great Basin shrub-steppe have initiated an upsurge in large rangeland wildfires and have increased the spatial and temporal vulnerability of these landscapes to amplified runoff and erosion. Resource and infrastructure damages, and loss of life have been reported due to flooding following recent large-scale burning of western rangelands and dry forests. We present a decade of post-fire rangeland hydrologic research that provides a foundation for conceptual modeling of the hydrologic impacts associated with an increased role of rangeland wildfires. We highlight advancements in predictive tools to address this large-scale phenomenon and discuss vital research voids requiring attention. Our geographic emphasis is the Great Basin Region, however, these concepts likely extend elsewhere given the increased role of fire in many geographic regions and across rangeland-to-forest ecotones in the western United States.

The quick and the deadly: Growth versus virulence in a seed bank pathogen

Treesearch

Susan E. Meyer; Thomas E. Stewart; Suzette Clement

2010-01-01

We studied the relationship between virulence (ability to kill nondormant Bromus tectorum seeds) and mycelial growth index in the necrotrophic seed pathogen Pyrenophora semeniperda. Seed pathosystems involving necrotrophs differ from those commonly treated in traditional evolution-of-virulence models in that host death increases pathogen fitness by preventing...

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

USDA-ARS?s Scientific Manuscript database

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...

Exotic annual Bromus invasions: comparisons among species and ecoregions in the western United States

USGS Publications Warehouse

Brooks, Matthew L.; Brown, Cynthia S.; Chambers, Jeanne C.; D'Antonio, Carla M.; Keeley, Jon E.; Belnap, Jayne

2016-01-01

Exotic annual Bromus species are widely recognized for their potential to invade, dominate, and alter the structure and function of ecosystems. In this chapter, we summarize the invasion potential, ecosystem threats, and management strategies for different Bromus species within each of five ecoregions of the western United States. We characterize invasion potential and threats in terms of ecosystem resistance to Bromus invasion and ecosystem resilience to disturbance with an emphasis on the importance of fi re regimes. We also explain how soil temperature and moisture regimes can be linked to patterns of resistance and resilience and provide a conceptual framework that can be used to evaluate the relative potential for invasion and ecological impact of the dominant exotic annual Bromus species in the western United States.

Soil moisture and biogeochemical factors influence the distribution of annual Bromus species

Treesearch

Jayne Belnap; John M. Stark; Benjamin M. Rau; Edith B. Allen; Susan Phillips

2016-01-01

Abiotic factors have a strong influence on where annual Bromus species are found. At the large regional scale, temperature and precipitation extremes determine the boundaries of Bromus occurrence. At the more local scale, soil characteristics and climate influence distribution, cover, and performance. In hot, dry, summer-rainfall-dominated deserts (Sonoran, Chihuahuan...

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.

Growth and nutrient content of herbaceous seedlings associated with biological soil crusts

Treesearch

R. L. Pendleton; B. K. Pendleton; G. L. Howard; S. D. Warren

2003-01-01

Biological soil crusts of arid and semiarid lands contribute significantly to ecosystem stability by means of soil stabilization, nitrogen fixation, and improved growth and establishment of vascular plant species. In this study, we examined growth and nutrient content of Bromus tectorum, Elymus elymoides, Gaillardia pulchella, and Sphaeralcea munroana grown in soil...

Invasion of the exotic grasses: Mapping their progression via satellite

Treesearch

Eric B. Peterson

2008-01-01

Several exotic annual grass species are invading the Intermountain West. After disturbances including wildfire, these grasses can form dense stands with fine fuels that then shorten fire intervals. Thus invasive annual grasses and wildfire form a positive feedback mechanism that threatens native ecosystems. Chief among these within Nevada are Bromus tectorum...

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.

The ghost of outcrossing past in downy brome, an inbreeding annual grass

Treesearch

Susan E. Meyer; Sudeep Ghimire; Samuel Decker; Keith R. Merrill; Craig E. Coleman

2013-01-01

We investigated the frequency of outcrossing in downy brome (Bromus tectorum L.), a cleistogamous weedy annual grass, in both common garden and wild populations, using microsatellite and single nucleotide polymorphic (SNP) markers. In the common garden study, 25 lines with strongly contrasting genotypes were planted in close proximity. We fingerprinted 10 seed progeny...

Mycelial growth rate and toxin production in the seed pathogen Pyrenophora semeniperda: Resource trade-offs and temporally varying selection

Treesearch

S. E. Meyer; M. Masi; S. Clement; T. L. Davis; J. Beckstead

2015-01-01

Pyrenophora semeniperda, an important pathogen in Bromus tectorum seed banks in semi-arid western North America, exhibits >4-fold variation in mycelial growth rate. Host seeds exhibit seasonal changes in dormancy that affect the risk of pathogen-caused mortality. The hypothesis tested is that contrasting seed dormancy phenotypes select for contrasting strategies...

A seed bank pathogen causes seedborne disease: Pyrenophora semeniperda on undispersed grass seeds in western North America

Treesearch

Susan E. Meyer; Julie Beckstead; Phil S. Allen; Duane C. Smith

2008-01-01

The generalist pathogen Pyrenophora semeniperda is abundant in seed banks of the exotic winter annual grass Bromus tectorum in semiarid western North America and is also found in the seed banks of co-occurring native grasses. In this study, we examined natural incidence of disease caused by this pathogen on undispersed host seeds,...

Ethnopharmacological uses of Sempervivum tectorum L. in southern Serbia: Scientific confirmation for the use against otitis linked bacteria.

PubMed

Stojković, Dejan; Barros, Lillian; Petrović, Jovana; Glamoclija, Jasmina; Santos-Buelga, Celestino; Ferreira, Isabel C F R; Soković, Marina

2015-12-24

Sempervivum tectorum L. (Crassulaceae), known as houseleek, is used in traditional medicine in the treatment of ear inflammation. It can be spread as a pack on wounds, sores, burns, and abscesses and also on painful areas attacked by gout as a refrigerant and astringent. Drinking tea prepared from leaves of S. tectorum is recommended for ulcer treatment. The present study was designed to investigate ethopharmacological use of S. tectorum in the southern Serbia and to further scientifically justify and confirm effectiveness of the leaf juice used in ethnomedicine for ear inflammation, against otitis linked bacteria. Ethnopharmacological survey on the use of S. tectorum in southern Serbia was performed using semi structured questionnaires via a face-to-face interview. Chemical composition of the leaf juice regarding phenolic compounds and organic acids was analyzed. Antimicrobial activity was tested on bacteria isolated from ear swabs of the patients suffering from the ear pain (otitis). Anti-quorum-sensing activities of the juice were further investigated on Pseudomonas aeruginosa. Ethnopharmacological survey revealed the use of S. tectorum in southern Serbia for the treatment of ear pain, warts, cancer, stomachache, ulcer and high blood sugar level with the highest fidelity level (FL) for the ear pain. The phenolic composition of the S. tectorum leaf juice consisted of flavonol glycosides, with kaempferol-3-O-rhamnosyl-glucoside-7-O-rhamnoside as the majority compound. Organic acids composition revealed malic acid as the most dominant one. Antimicrobial and anti-quorum-sensing activities of the juice showed to be promising. Ethnopharmacological use of S. tectorum juice for treating ear pain is justified, since the juice possessed antimicrobial activity towards clinical isolates of bacteria linked to otitis. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

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

Severe plant invasions can increase mycorrhizal fungal abundance and diversity.

PubMed

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

2013-07-01

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.

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

Ecology and space: A case study in mapping harmful invasive species

USGS Publications Warehouse

David T. Barnett,; Jarnevich, Catherine S.; Chong, Geneva W.; Stohlgren, Thomas J.; Sunil Kumar,; Holcombe, Tracy R.; Brunn, Stanley D.; Dodge, Martin

2017-01-01

The establishment and invasion of non-native plant species have the ability to alter the composition of native species and functioning of ecological systems with financial costs resulting from mitigation and loss of ecological services. Spatially documenting invasions has applications for management and theory, but the utility of maps is challenged by availability and uncertainty of data, and the reliability of extrapolating mapped data in time and space. The extent and resolution of projections also impact the ability to inform invasive species science and management. Early invasive species maps were coarse-grained representations that underscored the phenomena, but had limited capacity to direct management aside from development of watch lists for priorities for prevention and containment. Integrating mapped data sets with fine-resolution environmental variables in the context of species-distribution models allows a description of species-environment relationships and an understanding of how, why, and where invasions may occur. As with maps, the extent and resolution of models impact the resulting insight. Models of cheatgrass (Bromus tectorum) across a variety of spatial scales and grain result in divergent species-environment relationships. New data can improve models and efficiently direct further inventories. Mapping can target areas of greater model uncertainty or the bounds of modeled distribution to efficiently refine models and maps. This iterative process results in dynamic, living maps capable of describing the ongoing process of species invasions.

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.

Cheatgrass invasion “engineers” the soil to facilitate its growth

USDA-ARS?s Scientific Manuscript database

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...

Hydrothermal emergence model for ripgut brome (Bromus diandrus)

USDA-ARS?s Scientific Manuscript database

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 ...

Exotic annual Bromus invasions: Comparisons among species and ecoregions in the western United States [Chapter 2

Treesearch

Matthew L. Brooks; Cynthia S. Brown; Jeanne C. Chambers; Carla M. D' Antonio; Jon E. Keeley; Jayne Belnap

2016-01-01

Exotic annual Bromus species are widely recognized for their potential to invade, dominate, and alter the structure and function of ecosystems. In this chapter, we summarize the invasion potential, ecosystem threats, and management strategies for different Bromus species within each of five ecoregions of the western United States. We characterize invasion...

Preserving prairies: Understanding temporal and spatial patterns of invasive annual bromes in the Northern Great Plains

USGS Publications Warehouse

Ashton, Isabel; Symstad, Amy J.; Davis, Christopher; Swanson, Daniel J.

2016-01-01

Two Eurasian invasive annual brome grasses, cheatgrass (Bromus tectorum) and Japanese brome (Bromus japonicus), are well known for their impact in steppe ecosystems of the western United States where these grasses have altered fire regimes, reduced native plant diversity and abundance, and degraded wildlife habitat. Annual bromes are also abundant in the grasslands of the Northern Great Plains (NGP), but their impact and ecology are not as well studied. It is unclear whether the lessons learned from the steppe will translate to the mixed-grass prairie where native plant species are adapted to frequent fires and grazing. Developing a successful annual brome management strategy for National Park Service units and other NGP grasslands requires better understanding of (1) the impact of annual bromes on grassland condition; (2) the dynamics of these species through space and time; and (3) the relative importance of environmental factors within and outside managers' control for these spatiotemporal dynamics. Here, we use vegetation monitoring data collected from 1998 to 2015 in 295 sites to relate spatiotemporal variability of annual brome grasses to grassland composition, weather, physical environmental characteristics, and ecological processes (grazing and fire). Concern about the impact of these species in NGP grasslands is warranted, as we found a decline in native species richness with increasing annual brome cover. Annual brome cover generally increased over the time of monitoring but also displayed a 3- to 5-yr cycle of reduction and resurgence. Relative cover of annual bromes in the monitored areas was best predicted by park unit, weather, extant plant community, slope grade, soil composition, and fire history. We found no evidence that grazing reduced annual brome cover, but this may be due to the relatively low grazing pressure in our study. By understanding the consequences and patterns of annual brome invasion, we will be better able to preserve and restore

Antinociceptive activity of Sempervivum tectorum L. extract in rats.

PubMed

Kekesi, Gabriella; Dobos, Ildiko; Benedek, György; Horvath, Gyöngyi

2003-11-01

The extract of Sempervivum tectorum L. (Crassulaceae) containing several flavonoids is widely used as an antiinflammatory agent in folk medicine. Previous studies have demonstrated that various flavonoids or flavonoid-containing plant extracts produce significant antinociception, but no data are available concerning their antinociceptive effect especially at the spinal level. The purpose of the present study was to investigate the antinociceptive activity of Sempervivum tectorum L. extract on acute and inflammatory pain sensitivity in awake rats. The pain sensitivity was assessed by the acute tail- flick test in intact rats and by the paw withdrawal test after carrageenan-induced inflammation using heat stimulus. The plant extract was administered intraperitoneally and intrathecally in rats. The intraperitoneal injection of a high dose of the extract (1000 mg/kg) significantly (p < 0.05) increased the paw withdrawal latency of the inflamed paw. The intrathecal administration (30-300 micro g) caused a small, but significant increase (10%-15%) in tail- flick latency. In the carrageenan-induced inflammatory model, the intrathecally applied extract (30-1000 micro g) significantly decreased, but did not relieve the thermal hyperalgesia. The results suggest that the spinal cord does not seem to play an important role in the antinociceptive effects of this plant extract. Copyright 2003 John Wiley & Sons, Ltd.

Short-term effects of experimental fires on a Mojave Desert seed bank

USGS Publications Warehouse

Esque, Todd C.; Young, James A.; Tracy, C. Richard

2010-01-01

A Mojave Desert shrub community was experimentally burned to understand changes in seed bank of desert annual plant species in response to wildfire. Seed mortality ranged from 55 to 80%, and fire caused significant losses of native and alien annual seeds. Schismus arabicus, Schismus barbatus, Bromus madritensis, Bromus tectorum, Erodium cicutarium and Plantago spp. made up >95% of the seed bank. Bromus spp. and Plantago spp. had proportionately greater mortality of seeds than did Schismus spp. and E. cicutarium. Schismus spp. can be lodged into soil cracks thus avoiding lethal temperatures. E. cicutarium has a self-drilling mechanism that places the seeds at greater depth in the soil. Greater seed mortality occurred beneath shrub canopies than interspaces for most species (Plantago, spp., Bromus spp., and E. cicutarium), but microsite had little effect on Schismus spp. Fire reduced the perennial Ambrosia dumosa densities under canopies. Fire reduced the mean number of species found in samples by about one species per plot and no species was extirpated on experimental plots. The relative abundances of common species did not change dramatically as a result of fire or microsite, however; seed densities varied by treatment and affected interpretations of species compositions.

Weed-Suppressive Soil Bacteria to Reduce Cheatgrass and Improve Vegetation Diversity on ITD Rights-of-Way

DOT National Transportation Integrated Search

2017-06-01

Transportation departments are challenged by the invasion of downy brome (cheatgrass) and medusahead. The reduction of downy brome (cheat grass) by Weed Suppressive Bacteria (WSB) Pseudomonas fluorescens strain ACK55 was evaluated on roadsides of I-8...

Exotic Annual Grasses in Western Rangelands: Predicting Resistance and Resilience of Native Ecosystems to Invasion (Draft)

DTIC Science & Technology

2004-04-22

of these treatments to excessive salinity and ion-specific effects of the additives themselves. An exception to this was oxalic acid, which showed...Ca and HCO on P availability to plants. DeLucia et al. (1989) found that Bromus tectorum was P-limited in hydrothermally altered soils possessing...L. M. Dudley, et al. (1986). "The role of calcium oxalate in the availability of phosphorus in soils of semiarid regions: a thermodynamic study

Proceedings - Symposium on cheatgrass invasion, shrub die-off, and other aspects of shrub biology and management

Treesearch

E. Durant McArthur; Evan M. Romney; Stanley D. Smith; Paul T. Tueller

1990-01-01

Includes 45 papers and accounts of field trips from a symposium focused on a recent shrub die-off phenomenon and a perennial problem, cheatgrass invasion, on western rangelands. Contributions also cover shrub establishment, shrub ecosystem ecology and physiology, and plant and shrub ecosystems.

[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%.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Davies, G. M.; Bakker, J. D.; Dettweiler-Robinson, E.

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 themore » 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

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, Lesley A.; Bryla, David R.; Smith-Longozo, Vickie; Nowak, Robert 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 Bromuswas 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.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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%more » 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.« less

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.

Characterization of the Hanford 300 area burial grounds. Task IV. Biological transport

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fitzner, R.E.; Gano, K.A.; Rickard, W.H.

The characteristics of radioactive waste burial sites at the 300 area burial grounds on the Department of Energy's Hanford Site, southeastern Washington were studied. The potential vectors of radionuclide transport studied were vegetation and animals. The overall results showed a low potential for uptake and transport of radionuclides from the 300 area sites. However, additional methods to control physical and biological mechanisms may contribute to the effectiveness of waste burial practices. From the results, the Biological Transport task recommended field studies which include reduction of soil erosion and addition of biobarriers to plants and animals. Vegetation plays a major rolemore » in reducing soil erosion, and thereby maintaining the backfill over the burial sites. Of the several species found on the 300 area sites, cheatgrass (Bromus tectorum) appears to be the most desirable as a cover. Besides retarding erosion, it has a shallow root system (does not easily penetrate buried material); it has a low affinity for radionuclide uptake; and its tissues are not easily blown away. Small mammals (specifically, mice) appear to have the most potential for radionuclide exposure and uptake. Small mammals were live-trapped within 10 x 10-meter trap grids. Each animal trapped was surgically implanted with a thermoluminescent dosimeter. When the animal was recaptured, the dosimeter was removed and read for exposure. Exposures were reported in milli-Roentgens. The most consistently trapped small mammals were the Great Basin pocket mouse (Perognathus parvus) and the deer mouse (Peromyscus maniculatus). Results from the dosimeter readings showed that some of those animals had higher than background exposures. Biobarriers to animals could be considered as a mechanism to reduce the potential for radionuclide transport.« less

Integrative taxonomy: Combining morphological, molecular and chemical data for species delineation in the parthenogenetic Trhypochthonius tectorum complex (Acari, Oribatida, Trhypochthoniidae)

PubMed Central

2011-01-01

Background There is a long-standing controversial about how parthenogenetic species can be defined in absence of a generally accepted species concept for this reproductive mode. An integrative approach was suggested, combining molecular and morphological data to identify distinct monophyletic entities. Using this approach, speciation of parthenogenetic lineages was recently demonstrated for groups of bdelloid rotifers and oribatid mites. Trhypochthonius tectorum, an oribatid mite from the entirely parthenogenetic desmonomatan family Trhypochthoniidae, is traditionally treated as a single species in Central Europe. However, two new morphological lineages were recently proposed for some Austrian populations of T. tectorum, and were described as novel subspecies (T. silvestris europaeus) or form (T. japonicus forma occidentalis). We used the morphological and morphometrical data which led to this separation, and added mitochondrial and nuclear DNA sequences and the chemical composition of complex exocrine oil gland secretions to test this taxonomical hypothesis. This is the first attempt to combine these three types of data for integrative taxonomical investigations of oribatid mites. Results We show that the previous European species T. tectorum represents a species complex consisting of three distinct lineages in Austria (T.tectorum, T. silvestris europaeus and T. japonicus forma occidentalis), each clearly separated by morphology, oil gland secretion profiles and mitochondrial cox1 sequences. This diversification happened in the last ten million years. In contrast to these results, no variation among the lineages was found in the nuclear 18S rDNA. Conclusions Our approach combined morphological, molecular and chemical data to investigate diversity and species delineation in a parthenogenetic oribatid mite species complex. To date, hypotheses of a general oribatid mite phylogeny are manifold, and mostly based on single-method approaches. Probably, the integrative

Tentative identification of polyphenols in Sempervivum tectorum and assessment of the antimicrobial activity of Sempervivum L.

PubMed

Abram, V; Donko, M

1999-02-01

Polyphenols were isolated from sliced fresh leaves of Sempervivum tectorum. After 21 h of extraction by methanol and removal of chlorophyll, ethyl acetate was used to separate oligomeric and polymeric polyphenols: 0.07% of oligomeric and 0.13% of polymeric polyphenols were found. After acidic hydrolysis of the oligomeric polyphenols, it was established by TLC, HPLC, and FAB mass spectra that kaempferol was the unique aglycon of the three main oligomeric constituents of S. tectorum. Paper chromatography suggested delphinidol to be the only anthocyanidin detectable in the material obtained by acidic hydrolysis of the polymeric polyphenol fraction. After Haslam degradation of the same polymeric polyphenol fraction, only 4-thiobenzyl-(-)-epigallocatechin and 4-thiobenzyl-(-)-epigallocatechin-3-gallate were found and tentatively identified. We concluded that procyanidins of B2 type could be the major components of the polymeric polyphenol fraction of this plant. Antimicrobial activity of Sempervivum L. leaves against six of seven selected microorganisms was observed.

Effects of water additions, chemical amendments, and plants on in situ measures of nutrient bioavailability in calcareous soils of southeastern Utah, USA

USGS Publications Warehouse

Miller, M.E.; Belnap, J.; Beatty, S.W.; Webb, B.L.

2006-01-01

We used ion-exchange resin bags to investigate effects of water additions, chemical amendments, and plant presence on in situ measures of nutrient bioavailability in conjunction with a study examining soil controls of ecosystem invasion by the exotic annual grass Bromus tectorum L. At five dryland sites in southeastern Utah, USA, resin bags were buried in experimental plots randomly assigned to combinations of two watering treatments (wet and dry), four chemical-amendment treatments (KCl, MgO, CaO, and no amendment), and four plant treatments (B. tectorum alone, the perennial bunchgrass Stipa hymenoides R. & S. alone, B. tectorum and S. hymenoides together, and no plants). Resin bags were initially buried in September 1997; replaced in January, April, and June 1998; and removed at the end of the study in October 1998. When averaged across watering treatments, plots receiving KCl applications had lower resin-bag NO 3- than plots receiving no chemical amendments during three of four measurement periods-probably due to NO 3- displacement from resin bags by Cl- ions. During the January-April period, KCl application in wet plots (but not dry plots) decreased resin-bag NH 4+ and increased resin-bag NO 3- . This interaction effect likely resulted from displacement of NH 4+ from resins by K+ ions, followed by nitrification and enhanced NO 3- capture by resin bags. In plots not receiving KCl applications, resin-bag NH 4+ was higher in wet plots than in dry plots during the same period. During the January-April period, resin-bag measures for carbonate-related ions HPO 42- , Ca2+, and Mn2+ tended to be greater in the presence of B. tectorum than in the absence of B. tectorum. This trend was evident only in wet plots where B. tectorum densities were much higher than in dry plots. We attribute this pattern to the mobilization of carbonate-associated ions by root exudates of B. tectorum. These findings indicate the importance of considering potential indirect effects of soil

Life-history variation in Crepis tectorum (Asteraceae).

PubMed

Andersson, Stefan

1989-09-01

Populations of the monocarpic plant Crepis tectorum were grown in a series of uniform environments to test the hypothesis that weedy populations are more r-selected than populations from a more natural habitat. Weedy populations exhibited a combination of r- and K-selected traits. The relatively rapid growth, the potential for a summer annual habit, and the relatively high fecundity that characterized at least one of the two weed populations studied were considered as r-selected traits favored in habitats of unpredictable duration. However, high levels of competition from other weedy species or from the crop in arable fields may explain at least some presumably K-selected traits observed in the weedy populations, e.g. relatively large seeds and late flowering in the summer. Results indicated that stress due to abiotic factors (strong winds, desiccation and nutrient deficiency) has been a more important selective factor than r- or K-selection, in non-weedy populations from calcareous grasslands ("alvars") on the Baltic islands.

Land uses, fire, and invasion: Exotic annual Bromus and human dimensions [Chapter 11

Treesearch

David A. Pyke; Jeanne C. Chambers; Jeffrey L. Beck; Matthew L. Brooks; Brian A. Mealor

2016-01-01

Human land uses are the primary cause of the introduction and spread of exotic annual Bromus species. Initial introductions were likely linked to contaminated seeds used by homesteading farmers in the late 1880s and early 1900s. Transportation routes aided their spread. Unrestricted livestock grazing from the 1800s through the mid-1900s reduced native plant competitors...

Exotic plant invasion alters nitrogen dynamics in an arid grassland

USGS Publications Warehouse

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

2001-01-01

The introduction of nonnative plant species may decrease ecosystem stability by altering the availability of nitrogen (N) for plant growth. Invasive species can impact N availability by changing litter quantity and quality, rates of N2-fixation, or rates of N loss. We quantified the effects of invasion by the annual grass Bromus tectorum on N cycling in an arid grassland on the Colorado Plateau (USA). The invasion occurred in 1994 in two community types in an undisturbed grassland. This natural experiment allowed us to measure the immediate responses following invasion without the confounding effects of previous disturbance. Litter biomass and the C:N and lignin:N ratios were measured to determine the effects on litter dynamics. Long-term soil incubations (415 d) were used to measure potential microbial respiration and net N mineralization. Plant-available N was quantified for two years in situ with ion-exchange resin bags, and potential changes in rates of gaseous N loss were estimated by measuring denitrification enzyme activity. Bromus invasion significantly increased litter biomass, and Bromus litter had significantly greater C:N and lignin:N ratios than did native species. The change in litter quantity and chemistry decreased potential rates of net N mineralization in sites with Bromus by decreasing nitrogen available for microbial activity. Inorganic N was 50% lower on Hilaria sites with Bromus during the spring of 1997, but no differences were observed during 1998. The contrasting differences between years are likely due to moisture availability; spring precipitation was 15% greater than average during 1997, but 52% below average during spring of 1998. Bromus may cause a short-term decrease in N loss by decreasing substrate availability and denitrification enzyme activity, but N loss is likely to be greater in invaded sites in the long term because of increased fire frequency and greater N volatilization during fire. We hypothesize that the introduction of

Soils mediate the impact of fine woody debris on invasive and native grasses as whole trees are mechanically shredded into firebreaks in piñon-juniper woodlands

USGS Publications Warehouse

Aanderud, Zachary T.; Schoolmaster, Donald R.; Rigby, Deborah; Bybee, Jordon; Campbell, Tayte; Roundy, Bruce A.

2017-01-01

To stem wildfires, trees are being mechanically shredded into firebreaks with the resulting fine woody debris (FWD) potentially exerting immense control over soil and plants. We linked FWD-induced changes in microbial activity and nutrient availability to the frequency of Bromus tectorum and three native, perennial grasses across 31 piñon-juniper woodlands, UT, USA. Using a series of mixed models, we found that FWD increased the frequency of three of the four grasses by at least 12%. Deep, as opposed to shallow, soils mediated frequencies following FWD additions but only partially explained the variation in Bromus and Pseudoroegneria spicata. Although fertile areas associated with tree-islands elicited no response, FWD-induced increases in nitrogen mineralization in deep soils (15–17 cm) caused the frequency of the exotic and Pseudoroegneria to rise. Higher phosphorus availability in FWD-covered surface soils (0–2 cm) had no impact on grasses. FWD altered deep soil respiration, and deep and shallow microbial biomass structuring Pseudoroegneria frequencies, suggesting that microorganism themselves regulated Pseudoroegneria. The positive effects of FWD on grass frequencies intensified over time for natives but diminished for Bromus. Our results demonstrate that microorganisms in deeper soils helped mediate species-specific responses to disturbance both facilitating exotic invasion and promoting native establishment.

Developing Functional Parameters for a Science-Based Vehicle Cleaning Program to Reduce Transport of Non-Indigenous Invasive Plant Species

DTIC Science & Technology

2011-06-01

49 B3 Risk map for Bromus tectorum……………………………………………………………...50 B4 Risk map for Centaurea maculosa …………………………………………………………..51 B5 Risk map...tectorum Centaurea maculosa Cirsium arvense Linaria dalmatica Verbascum thapsus Intercept -5.89384 7.63606 2.10221 -447.2744 -36.33253 -2.07618... maculosa (spotted knapweed), Cirsium arvense (Canada thistle), Linaria dalmatica (Dalmation toadflax), and Verbascum thapsus (common mullein

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. 

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.

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

Facilitation and interference of seedling establishment by a native legume before and after wildfire.

PubMed

Goergen, Erin; Chambers, Jeanne C

2012-01-01

In semi-arid ecosystems, heterogeneous resources can lead to variable seedling recruitment. Existing vegetation can influence seedling establishment by modifying the resource and physical environment. We asked how a native legume, Lupinus argenteus, modifies microenvironments in unburned and burned sagebrush steppe, and if L. argenteus presence facilitates seedling establishment of native species and the non-native annual grass, Bromus tectorum. Field treatments examined mechanisms by which L. argenteus likely influences establishment: (1) live L. argenteus; (2) dead L. argenteus; (3) no L. argenteus; (4) no L. argenteus with L. argenteus litter; (5) no L. argenteus with inert litter; and (6) mock L. argenteus. Response variables included soil nitrogen, moisture, temperature, solar radiation, and seedling establishment of the natives Elymus multisetus and Eriogonum umbellatum, and non-native B. tectorum. In both unburned and burned communities, there was higher spring soil moisture, increased shade and reduced maximum temperatures under L. argenteus canopies. Adult L. argenteus resulted in greater amounts of soil nitrogen (N) only in burned sagebrush steppe, but L. argenteus litter increased soil N under both unburned and burned conditions. Although L. argenteus negatively affected emergence and survival of B. tectorum overall, its presence increased B. tectorum biomass and reproduction in unburned plots. However, L. argenteus had positive facilitative effects on size and survival of E. multisetus in both unburned and burned plots. Our study indicates that L. argenteus can facilitate seedling establishment in semi-arid systems, but net effects depend on the species examined, traits measured, and level of abiotic stress.

Antioxidant activity of Sempervivum tectorum and its components.

PubMed

Sentjurc, Marjeta; Nemec, Marjana; Connor, Henry D; Abram, Veronika

2003-04-23

The antioxidant properties of components of leaf extracts of the evergreen plant, Sempervivum tectorum (ST), have been evaluated using UV irradiated liposomal systems containing the spin trap 5-(diethoxyphosphoryl)-5-methyl-pyrroline-N-oxide. Decreases in free radical activity in the liposomal systems as measured by electron paramagnetic resonance (EPR) spectroscopy demonstrate that the lipophilic ST juice components, kaempferol (KA) and kaempferol-3-glucoside (KG) contribute significantly to the antioxidant properties of the juice. EPR spectral simulation established the presence of oxygen and carbon centered free radical adducts. The mixtures with low pH, citric and malic acid, and ST juice reveal increased EPR signals from oxygen centered radicals in comparison to the control, pointing to the important role of pH in oxygen radical formation. Parallel assays that measured thiobarbituric acid related substances confirm the antioxidant effects of KA and KG and explain the results of spin trapping experiments complicated by low pH's.

The importance of disturbance by fire and other abiotic and biotic factors in driving cheatgrass invasion varies based on invasion stage

Treesearch

Becky K. Kerns; Michelle A. Day

2017-01-01

Disturbances create fluctuations in resource availability that alter abiotic and biotic constraints. Exotic invader response may be due to multiple factors related to disturbance regimes and complex interactions between other small- and largescale abiotic and biotic processes that may vary across invasion stages. We explore how cheatgrass responds to both frequency and...

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

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

Treesearch

R.C. Johnson; Vicky J. Erickson; Nancy L. Mandel; J. Bradley St. Clair; Kenneth W. Vance-Borland

2010-01-01

Seed transfer zones ensure that germplasm selected for restoration is suitable and sustainable in diverse environments. In this study, seed zones were developed for mountain brome (Bromus carinatus Hook. & Arn.) in the Blue Mountains of northeastern Oregon and adjoining Washington. Plants from 148 Blue Mountain seed source locations were...

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

USDA-ARS?s Scientific Manuscript database

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...

Metabolic alterations of toxic and nonessential elements by the treatment of Sempervivum tectorum extract in a hyperlipidemic rat model.

PubMed

Szentmihályi, Klára; Fehér, Erzsébet; Vinkler, Péter; Kéry, Agnes; Blázovics, Anna

2004-01-01

A hyperlipidemic rat model was used to examine the therapeutic effect of Sempervivum tectorum plant extract on the metabolic alterations of Al, As, B, Ba, Cd, Hg, Ni, Pb, and Ti in the liver and bile. Hyperlipidemia was produced by lipogenic diet and alcohol and verified by morphological investigation of the liver with the aid of light and an electron microscope. Element concentration in the liver and bile were determined by inductively coupled plasma optical emission spectrometry (ICP-OES). The concentration values in the liver higher than the detection limit (Al, Ba, Ni, Ti) were unambiguous. Significant differences were found for the four groups at p < 0.05 level (ANOVA). A significant difference was observed between Al and B concentration in the bile fluids of the 4 groups (p < 0.05). The excretion of Al and Ti into the bile fluid increased significantly (p < 0.05). Following the administration of S. tectorum extract to rats with hyperlipidemia, the excretion of Al, B and Ba increased, whereas the excretion of Ti decreased significantly (p < 0.05). The favorable action of the extract (protecting the liver in hyperlipidemic rats) was verified by morphological studies, and its detoxicating property was shown by the elimination of Al, Ba, Ni, and Ti from the liver.

Effects of nutrient patches and root systems on the clonal plasticity of a rhizomatous grass

USGS Publications Warehouse

Huber-Sannwald, Elisabeth; Pyke, David A.; Caldwell, M.M.; Durham, S.

1998-01-01

Clonal plant foraging has been examined primarily on individual clones exposed to resource-poor and resource-rich environments. We designed an experiment to examine the clonal foraging behavior of the rhizomatous grass Elymus lanceolatus ssp. lanceolatus under the influence of neighboring plant root systems in a heterogeneous nutrient environment. Individual Elymus clones were planted in large bins together with one of three neighboring grass species, Agropyron desertorum, Pseudoroegneria spicata, or Bromus tectorum, which differ in rooting density and growth activity. The position of Elymus clones was manipulated so rhizomes encountered a short-duration nutrient patch and subsequently root systems of the neighboring plants. Unexpectedly, the morphological plasticity of the perennial grass Elymus lanceolatus ssp. lanceolatus was influenced by the presence of the neighboring species much more than by the local nutrient enrichments, although nutrient patches did amplify some of the foraging responses. Elymus rhizomes branched readily and initiated large daughter plants as they encountered the low-density root systems of Pseudoroegneria. When Elymus encountered the fine, dense root systems of the annual Bromus, clonal expansion was initially reduced. Yet, after the short growing season of Bromus, Elymus resumed clonal expansion and produced several daughter plants. Elymus clones were most constrained by the fine, dense root systems of Agropyron desertorum. In this case, a few, long rhizomes avoided the densely rooted soil environment by growing aboveground as stolons crossing over the Agropyron tussocks. Elymus clonal biomass was largest in neighborhoods of Pseudoroegneria, intermediate in neighborhoods with Bromus, and smallest in neighborhoods with Agropyron. The latter were approximately half the size of those in the Pseudoroegneria environments. Elymus growth could not be explained by simple resource competition alone; other mechanisms must have been involved in

Soil biota can change after exotic plant invasion: Does this affect ecosystem processes?

USGS Publications Warehouse

Belnap, J.; Phillips, S.L.; Sherrod, S.K.; Moldenke, A.

2005-01-01

Invasion of the exotic annual grass Bromus tectorum into stands of the native perennial grass Hilaria jamesii significantly reduced the abundance of soil biota, especially microarthropods and nematodes. Effects of invasion on active and total bacterial and fungal biomass were variable, although populations generally increased after 50+ years of invasion. The invasion of Bromus also resulted in a decrease in richness and a species shift in plants, microarthropods, fungi, and nematodes. However, despite the depauperate soil fauna at the invaded sites, no effects were seen on cellulose decomposition rates, nitrogen mineralization rates, or vascular plant growth. When Hilaria was planted into soils from not-invaded, recently invaded, and historically invaded sites (all currently or once dominated by Hilaria), germination and survivorship were not affected. In contrast, aboveground Hilaria biomass was significantly greater in recently invaded soils than in the other two soils. We attributed the Hilaria response to differences in soil nutrients present before the invasion, especially soil nitrogen, phosphorus, and potassium, as these nutrients were elevated in the soils that produced the greatest Hilaria biomass. Our data suggest that it is not soil biotic richness per se that determines soil process rates or plant productivity, but instead that either (1) the presence of a few critical soil food web taxa can keep ecosystem function high, (2) nutrient loss is very slow in this ecosystem, and/or (3) these processes are microbially driven. However, the presence of Bromus may reduce key soil nutrients over time and thus may eventually suppress native plant success. ?? 2005 by the Ecological Society of America.

The quick and the deadly: growth vs virulence in a seed bank pathogen.

PubMed

Meyer, Susan E; Stewart, Thomas E; Clement, Suzette

2010-07-01

*We studied the relationship between virulence (ability to kill nondormant Bromus tectorum seeds) and mycelial growth index in the necrotrophic seed pathogen Pyrenophora semeniperda. Seed pathosystems involving necrotrophs differ from those commonly treated in traditional evolution-of-virulence models in that host death increases pathogen fitness by preventing germination, thereby increasing available resources. Because fast-germinating, nondormant B. tectorum seeds commonly escape mortality, we expected virulence to be positively correlated with mycelial growth index. *We performed seed inoculations using conidia from 78 pathogen isolates and scored subsequent mortality. For a subset of 40 of these isolates, representing a range of virulence phenotypes, we measured mycelial growth index. *Virulence varied over a wide range (3-43% seed mortality) and was significantly negatively correlated with mycelial growth index (R(2) = 0.632). More virulent isolates grew more slowly than less virulent isolates. *We concluded that there is an apparent tradeoff between virulence and growth in this pathogen, probably because the production of toxins necessary for necrotrophic pathogenesis competes with metabolic processes associated with growth. Variation in both virulence and growth rate in this pathosystem may be maintained in part by seasonal variation in the relative abundance of rapidly germinating vs dormant host seeds available to the pathogen.

Post-fire interactions between soil water repellency, soil fertility and plant growth in soil collected from a burned piñon-juniper woodland

USGS Publications Warehouse

Fernelius, Kaitlynn J.; Madsen, Matthew D.; Hopkins, Bryan G.; Bansal, Sheel; Anderson, Val J.; Eggett, Dennis L.; Roundy, Bruce A.

2017-01-01

Woody plant encroachment can increase nutrient resources in the plant-mound zone. After a fire, this zone is often found to be water repellent. This study aimed to understand the effects of post-fire water repellency on soil water and inorganic nitrogen and their effects on plant growth of the introduced annual Bromus tectorum and native bunchgrass Pseudoroegneria spicata. Plots centered on burned Juniperus osteosperma trees were either left untreated or treated with surfactant to ameliorate water repellency. After two years, we excavated soil from the untreated and treated plots and placed it in zerotension lysimeter pots. In the greenhouse, half of the pots received an additional surfactant treatment. Pots were seeded separately with B. tectorum or P. spicata. Untreated soils had high runoff, decreased soilwater content, and elevated NO3eN in comparison to surfactant treated soils. The two plant species typically responded similar to the treatments. Above-ground biomass and microbial activity (estimated through soil CO2 gas emissions) was 16.8-fold and 9.5-fold higher in the surfactant-treated soils than repellent soils, respectably. This study demonstrates that water repellency can influence site recovery by decreasing soil water content, promoting inorganic N retention, and impairing plant growth and microbial activity.

Refining the cheatgrass-fire cycle in the Great Basin: Precipitation timing and fine fuel composition predict wildfire trends.

PubMed

Pilliod, David S; Welty, Justin L; Arkle, Robert S

2017-10-01

Larger, more frequent wildfires in arid and semi-arid ecosystems have been associated with invasion by non-native annual grasses, yet a complete understanding of fine fuel development and subsequent wildfire trends is lacking. We investigated the complex relationships among weather, fine fuels, and fire in the Great Basin, USA. We first modeled the annual and time-lagged effects of precipitation and temperature on herbaceous vegetation cover and litter accumulation over a 26-year period in the northern Great Basin. We then modeled how these fine fuels and weather patterns influence subsequent wildfires. We found that cheatgrass cover increased in years with higher precipitation and especially when one of the previous 3 years also was particularly wet. Cover of non-native forbs and native herbs also increased in wet years, but only after several dry years. The area burned by wildfire in a given year was mostly associated with native herb and non-native forb cover, whereas cheatgrass mainly influenced area burned in the form of litter derived from previous years' growth. Consequently, multiyear weather patterns, including precipitation in the previous 1-3 years, was a strong predictor of wildfire in a given year because of the time needed to develop these fine fuel loads. The strong relationship between precipitation and wildfire allowed us to expand our inference to 10,162 wildfires across the entire Great Basin over a 35-year period from 1980 to 2014. Our results suggest that the region's precipitation pattern of consecutive wet years followed by consecutive dry years results in a cycle of fuel accumulation followed by weather conditions that increase the probability of wildfire events in the year when the cycle transitions from wet to dry. These patterns varied regionally but were strong enough to allow us to model annual wildfire risk across the Great Basin based on precipitation alone.

Modelling invasion for a habitat generalist and a specialist plant species

USGS Publications Warehouse

Evangelista, P.H.; Kumar, S.; Stohlgren, T.J.; Jarnevich, C.S.; Crall, A.W.; Norman, J. B.; Barnett, D.T.

2008-01-01

Predicting suitable habitat and the potential distribution of invasive species is a high priority for resource managers and systems ecologists. Most models are designed to identify habitat characteristics that define the ecological niche of a species with little consideration to individual species' traits. We tested five commonly used modelling methods on two invasive plant species, the habitat generalist Bromus tectorum and habitat specialist Tamarix chinensis, to compare model performances, evaluate predictability, and relate results to distribution traits associated with each species. Most of the tested models performed similarly for each species; however, the generalist species proved to be more difficult to predict than the specialist species. The highest area under the receiver-operating characteristic curve values with independent validation data sets of B. tectorum and T. chinensis was 0.503 and 0.885, respectively. Similarly, a confusion matrix for B. tectorum had the highest overall accuracy of 55%, while the overall accuracy for T. chinensis was 85%. Models for the generalist species had varying performances, poor evaluations, and inconsistent results. This may be a result of a generalist's capability to persist in a wide range of environmental conditions that are not easily defined by the data, independent variables or model design. Models for the specialist species had consistently strong performances, high evaluations, and similar results among different model applications. This is likely a consequence of the specialist's requirement for explicit environmental resources and ecological barriers that are easily defined by predictive models. Although defining new invaders as generalist or specialist species can be challenging, model performances and evaluations may provide valuable information on a species' potential invasiveness.

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

Treesearch

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

2014-01-01

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...

Bromus tectorum expansion and biodiversity loss on the Snake River Plain, southern Idaho, USA

Treesearch

N. L. Shaw; V. A. Saab; S. B. Monsen; T. D. Rich

1999-01-01

The Snake River Plain forms a 6 million ha arc-shaped depression across southern Idaho. Basalt flows, fresh water sediments, loess and volcanic deposits cover its surface. Elevation increases eastward from 650 to 2,150 m altitude. Climate is semi-arid with annual precipitation ranging from 150 to 400 mm, arriving primarily in winter and spring. Native shrub steppe...

Enhanced fire-related traits may contribute to the invasiveness of Downy Brome (Bromus tectorum)

USDA-ARS?s Scientific Manuscript database

Although several invasive species have induced changes to the fire regime of invaded ecosystems, potential intraspecific shifts in fire-related traits that might enhance their invasion success, have never been addressed. We assumed that traits conferring persistence and competitiveness in post-fire ...

Rehabilitating downy brome (Bromus tectorum)-invaded scrublands using imazapic and seeding with native shrubs

Treesearch

Suzanne M. Owen; Carolyn Hull Sieg; Catherine A. Gehring

2011-01-01

Rehabilitation of downy brome-infested shrublands is challenging once this invasive grass dominates native communities. The effectiveness of imazapic herbicide in reducing downy brome cover has been variable, and there is uncertainty about the impacts of imazapic on native species. We used a before-after-control-impact (BACI) field experiment and greenhouse studies to...

Local population differentiation in Bromus tectorum L. in relation to habitat-specific selection regimes

Treesearch

Jason W. Scott; Susan E. Meyer; Keith R. Merrill; Val J. Anderson

2010-01-01

A central question of invasion biology is how an exotic species invades new habitats following its initial establishment. Three hypotheses to explain this expansion are: (1) the existence of 'general purpose' genotypes, (2) the in situ evolution of novel genotypes, and (3) the dispersal of existing specialized genotypes into habitats for which they are pre-...

Composted manure application promotes long-term invasion of semi-arid rangeland by Bromus tectorum

USDA-ARS?s Scientific Manuscript database

Composted organic matter derived from sewage treatment facilities or livestock manure from feedlots is often applied to rangelands of western North America to increase soil fertility, forage production, forage quality, and soil carbon (C) storage. This practice can have a number of undesirable side ...

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

Quantifying and predicting fuels and the effects of reduction treatments along successional and invasion gradients in sagebrush habitats

USGS Publications Warehouse

Shinneman, Douglas; Pilliod, David S.; Arkle, Robert; Glenn, Nancy F.

2015-01-01

Sagebrush shrubland ecosystems in the Great Basin are prime examples of how altered successional trajectories can create dynamic fuel conditions and, thus, increase uncertainty about fire risk and behavior. Although fire is a natural disturbance in sagebrush, post-fire environments are highly susceptible to conversion to an invasive grass-fire regime (often referred to as a “grass-fire cycle”). After fire, native shrub-steppe plants are often slow to regenerate, whereas nonnative annuals, especially cheatgrass (Bromus tectorum) and medusahead (Taeniatherum caput-medusae), can establish quickly and outcompete native species. Once fire-prone annuals become established, fire occurrences increase, further promoting dominance of nonnative species. The invasive grass-fire regime also alters nutrient and hydrologic cycles, pushing ecosystems beyond ecological thresholds toward steady-state, fire-prone, nonnative communities. These changes affect millions of hectares in the Great Basin and increase fire risk, decrease habitat quality and biodiversity, accelerate soil erosion, and degrade rangeland resources for livestock production. In many sagebrush landscapes, constantly changing plant communities and fuel conditions hinder attempts by land managers to predict and control fire behavior, restore native communities, and provide ecosystem services (e.g., forage production for livestock). We investigated successional and nonnative plant invasion states and associated fuel loads in degraded sagebrush habitat in a focal study area, the Morley Nelson Snake River Birds of Prey National Conservation Area (hereafter the NCA), in the Snake River Plain Ecoregion of southern Idaho. We expanded our inference by comparing our findings to similar data collected throughout seven major land resource areas (MLRAs) across the Great Basin (JFSP Project “Fire Rehabilitation Effectiveness: A Chronosequence Approach for the Great Basin” [09-S-02-1]). 4 We used a combination of field

Sagebrush ecosystems: current status and trends.

USGS Publications Warehouse

Beever, E.A.; Connelly, J.W.; Knick, S.T.; Schroeder, M.A.; Stiver, S. J.

2004-01-01

The sagebrush (Artemisia spp.) biome has changed since settlement by Europeans. The current distribution, composition and dynamics, and disturbance regimes of sagebrush ecosystems have been altered by interactions among disturbance, land use, and invasion of exotic plants. In this chapter, we present the dominant factors that have influenced habitats across the sagebrush biome. Using a large-scale analysis, we identified regional changes and patterns in “natural disturbance”, invasive exotic species, and influences of land use in sagebrush systems. Number of fires and total area burned has increased since 1980 across much of the sagebrush biome. Juniper (Juniperus spp.) and pinyon (Pinus spp.) woodlands have expanded into sagebrush habitats at higher elevations. Cheatgrass (Bromus tectorum), an exotic annual grass, has invaded much of lower elevation, more xeric sagebrush landscapes across the western portion of the biome. Consequently, synergistic feedbacks between habitats and disturbance (natural and human-caused) have altered disturbance regimes, plant community dynamics and contributed to loss of sagebrush habitats and change in plant communities. Habitat conversion to agriculture has occurred in the highly productive regions of the sagebrush biome and influenced up to 56% of the Conservation Assessment area. Similarly, urban areas, and road, railroad, and powerline networks fragment habitats, facilitate predator movements, and provide corridors for spread of exotic species across the entire sagebrush biome. Livestock grazing has altered sagebrush habitats; the effects of overgrazing combined with drought on plant communities in the late 1880s and early 1900s still influences current habitats. Management of livestock grazing has influenced sagebrush ecosystems by habitat treatments to increase forage and reduce sagebrush and other plant species unpalatable to livestock. Fences, roads, and water developments to manage livestock movements have further

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. Copyright �

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

Characterization of phenolic compounds and antinociceptive activity of Sempervivum tectorum L. leaf juice.

PubMed

Alberti, Ágnes; Béni, Szabolcs; Lackó, Erzsébet; Riba, Pál; Al-Khrasani, Mahmoud; Kéry, Ágnes

2012-11-01

Sempervivum tectorum L. (houseleek) leaf juice has been known as a traditional herbal remedy. The aim of the present study was the chemical characterization of its phenolic compounds and to develop quantitation methods for its main flavonol glycoside, as well as to evaluate its antinociceptive activity. Lyophilized houseleek leaf juice was studied by HPLC-DAD coupled to electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) to identify flavonol glycosides, hydroxy-benzoic and hydroxy-cinnamic acids. Ten flavonol glycosides and sixteen phenolic acid compounds were identified or tentatively characterized. Structure of the main flavonol compound was identified by nuclear magnetic resonance spectroscopy. Three characteristic kaempferol glycosides were isolated and determined by LC-ESI-MS/MS with external calibration method, using the isolated compounds as standard. The main flavonol glycoside was also determined by HPLC-DAD. Validated HPLC-DAD and LC-ESI-MS/MS methods were developed to quantify kaempferol-3-O-rhamnosyl-glucoside-7-O-rhamnoside and two other kaempferol glycosides. Antinociceptive activity of houseleek leaf juice was investigated by writhing test of mice. Sempervivum extract significantly reduced pain in the mouse writhing test. Copyright © 2012 Elsevier B.V. All rights reserved.

Revisiting the Life Cycle of Dung Fungi, Including Sordaria fimicola.

PubMed

Newcombe, George; Campbell, Jason; Griffith, David; Baynes, Melissa; Launchbaugh, Karen; Pendleton, Rosemary

2016-01-01

Dung fungi, such as Sordaria fimicola, generally reproduce sexually with ascospores discharged from mammalian dung after passage through herbivores. Their life cycle is thought to be obligate to dung, and thus their ascospores in Quaternary sediments have been interpreted as evidence of past mammalian herbivore activity. Reports of dung fungi as endophytes would seem to challenge the view that they are obligate to dung. However, endophyte status is controversial because surface-sterilization protocols could fail to kill dung fungus ascospores stuck to the plant surface. Thus, we first tested the ability of representative isolates of three common genera of dung fungi to affect plant growth and fecundity given that significant effects on plant fitness could not result from ascospores merely stuck to the plant surface. Isolates of S. fimicola, Preussia sp., and Sporormiella sp. reduced growth and fecundity of two of three populations of Bromus tectorum, the host from which they had been isolated. In further work with S. fimicola we showed that inoculations of roots of B. tectorum led to some colonization of aboveground tissues. The same isolate of S. fimicola reproduced sexually on inoculated host plant tissues as well as in dung after passage through sheep, thus demonstrating a facultative rather than an obligate life cycle. Finally, plants inoculated with S. fimicola were not preferred by sheep; preference had been expected if the fungus were obligate to dung. Overall, these findings make us question the assumption that these fungi are obligate to dung.

Revisiting the Life Cycle of Dung Fungi, Including Sordaria fimicola

PubMed Central

Newcombe, George; Campbell, Jason; Griffith, David; Baynes, Melissa; Launchbaugh, Karen; Pendleton, Rosemary

2016-01-01

Dung fungi, such as Sordaria fimicola, generally reproduce sexually with ascospores discharged from mammalian dung after passage through herbivores. Their life cycle is thought to be obligate to dung, and thus their ascospores in Quaternary sediments have been interpreted as evidence of past mammalian herbivore activity. Reports of dung fungi as endophytes would seem to challenge the view that they are obligate to dung. However, endophyte status is controversial because surface-sterilization protocols could fail to kill dung fungus ascospores stuck to the plant surface. Thus, we first tested the ability of representative isolates of three common genera of dung fungi to affect plant growth and fecundity given that significant effects on plant fitness could not result from ascospores merely stuck to the plant surface. Isolates of S. fimicola, Preussia sp., and Sporormiella sp. reduced growth and fecundity of two of three populations of Bromus tectorum, the host from which they had been isolated. In further work with S. fimicola we showed that inoculations of roots of B. tectorum led to some colonization of aboveground tissues. The same isolate of S. fimicola reproduced sexually on inoculated host plant tissues as well as in dung after passage through sheep, thus demonstrating a facultative rather than an obligate life cycle. Finally, plants inoculated with S. fimicola were not preferred by sheep; preference had been expected if the fungus were obligate to dung. Overall, these findings make us question the assumption that these fungi are obligate to dung. PMID:26839959

Vegetation of steep slopes in the shrub-steppe region of south-central Washington

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sauer, R H; Rickard, W H

1977-01-01

This paper presents data and conclusions concerning the vegetation and soils of steep natural slopes of arid regions. Cover by species and soil physical and chemical properties were taken from 10 canyons along the Columbia River north of Pasco, Washington. Vegetative cover was significantly different and averaged 25 percent on the south-facing and 72 percent on the north-facing slopes. The mean number of species were significantly different. Four species were restricted to the south slopes, 10 were restricted to the north slopes, and 23 were common to both. Poa sandbergii and Agropyron spicatum, native perennial grasses, dominated the north-facing slopesmore » and Bromus tectorum, an alien annual grass, dominated the south-facing slopes. Soils were shallower and rockier on the south-facing slopes. Even though vegetative cover and number of species were different, the similar number of dominant species suggest community functions are nonetheless similar in these contrasting environments.« less

Herbicidal Activity of Glucosinolate Degradation Products in Fermented Meadowfoam (Limnanthes alba) Seed Meal

PubMed Central

STEVENS, JAN F.; REED, RALPH L.; ALBER, SUSAN; PRITCHETT, LARRY; MACHADO, STEPHEN

2009-01-01

Meadowfoam (Limnanthes alba) is an oilseed crop grown in western Oregon. After extraction of the oil from the seeds, the remaining seed meal contains 2-4% of the glucosinolate, glucolimnanthin. We investigated the effect of fermentation of seed meal on its chemical composition and the effect of the altered composition on downy brome (Bromus tectorum) coleoptile emergence. Incubation of enzyme-inactive seed meal with enzyme-active seeds (1% by weight) resulted in complete degradation of glucolimnanthin and formation of 3-methoxybenzyl isothiocyanate in 28% yield. Fermentation in the presence of an aqueous solution of FeSO4 (10 mM) resulted in the formation of 3-methoxyphenylacetonitrile and 2-(3-methoxyphenyl)ethanethioamide, a novel natural product. The formation of the isothiocyanate, the nitrile and the thioamide, as a total, correlated with an increase of herbicidal potency of seed meal (r2 = 0.96). The results of this study open new possibilities for the refinement of glucosinolate-containing seed meals for use as bioherbicides. PMID:19170637

Herbicidal activity of glucosinolate degradation products in fermented meadowfoam ( Limnanthes alba ) seed meal.

PubMed

Stevens, Jan F; Reed, Ralph L; Alber, Susan; Pritchett, Larry; Machado, Stephen

2009-03-11

Meadowfoam ( Limnanthes alba ) is an oilseed crop grown in western Oregon. After extraction of the oil from the seeds, the remaining seed meal contains 2-4% of the glucosinolate glucolimnanthin. This study investigated the effect of fermentation of seed meal on its chemical composition and the effect of the altered composition on downy brome ( Bromus tectorum ) coleoptile emergence. Incubation of enzyme-inactive seed meal with enzyme-active seeds (1% by weight) resulted in complete degradation of glucolimnanthin and formation of 3-methoxybenzyl isothiocyanate in 28% yield. Fermentation in the presence of an aqueous solution of FeSO(4) (10 mM) resulted in the formation of 3-methoxyphenylacetonitrile and 2-(3-methoxyphenyl)ethanethioamide, a novel natural product. The formation of the isothiocyanate, the nitrile, and the thioamide, as a total, correlated with an increase of herbicidal potency of the seed meal (r(2) = 0.96). The results of this study open new possibilities for the refinement of glucosinolate-containing seed meals for use as bioherbicides.

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 Stipa 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.

Arbuscular mycorrhizal assemblages in native plant roots change in the presence of invasive exotic grasses

USGS Publications Warehouse

Hawkes, C.V.; Belnap, J.; D'Antonio, C.; Firestone, M.K.

2006-01-01

Plant invasions have the potential to significantly alter soil microbial communities, given their often considerable aboveground effects. We examined how plant invasions altered the arbuscular mycorrhizal fungi of native plant roots in a grassland site in California and one in Utah. In the California site, we used experimentally created plant communities composed of exotic (Avena barbata, Bromus hordeaceus) and native (Nassella pulchra, Lupinus bicolor) monocultures and mixtures. In the Utah semi-arid grassland, we took advantage of invasion by Bromus tectorum into long-term plots dominated by either of two native grasses, Hilaria jamesii or Stipa hymenoides. Arbuscular mycorrhizal fungi colonizing roots were characterized with PCR amplification of the ITS region, cloning, and sequencing. We saw a significant effect of the presence of exotic grasses on the diversity of mycorrhizal fungi colonizing native plant roots. In the three native grasses, richness of mycorrhizal fungi decreased; in the native forb at the California site, the number of fungal RFLP patterns increased in the presence of exotics. The exotic grasses also caused the composition of the mycorrhizal community in native roots to shift dramatically both in California, with turnover of Glomus spp., and Utah, with replacement of Glomus spp. by apparently non-mycorrhizal fungi. Invading plants may be able to influence the network of mycorrhizal fungi in soil that is available to natives through either earlier root activity or differential carbon provision compared to natives. Alteration of the soil microbial community by plant invasion can provide a mechanism for both successful invasion and the resulting effects of invaders on the ecosystem. ?? Springer 2006.

Range-wide patterns of greater sage-grouse persistence

USGS Publications Warehouse

Aldridge, Cameron L.; Nielsen, Scott E.; Beyer, Hawthorne L.; Boyce, Mark S.; Connelly, John W.; Knick, Steven T.; Schroeder, Michael 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.

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

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

USDA-ARS?s Scientific Manuscript database

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...

Can native annual forbs reduce Bromus tectorum biomass and indirectly facilitate establishment of a native perennial grass?

Treesearch

Elizabeth A. Leger; Erin M. Goergen; Tara Forbis de Queiroz

2014-01-01

Restoration is challenging in systems invaded by competitive, disturbance oriented plants, but greater success may be achieved by mimicking natural successional processes and including disturbanceoriented natives in a seed mix. We asked whether seven native annual forbs from the Great Basin Desert, USA, were capable of reducing biomass of the invasive annual grass...

Constructing Hierarchical Tectorum-like α-Fe2 O3 /PPy Nanoarrays on Carbon Cloth for Solid-State Asymmetric Supercapacitors.

PubMed

Wang, Libin; Yang, Huiling; Liu, Xiaoxiao; Zeng, Rui; Li, Ming; Huang, Yunhui; Hu, Xianluo

2017-01-19

The design of complex heterostructured electrode materials that deliver superior electrochemical performances to their individual counterparts has stimulated intensive research on configuring supercapacitors with high energy and power densities. Herein we fabricate hierarchical tectorum-like α-Fe 2 O 3 /polypyrrole (PPy) nanoarrays (T-Fe 2 O 3 /PPy NAs). The 3D, and interconnected T-Fe 2 O 3 /PPy NAs are successfully grown on conductive carbon cloth through an easy self-sacrificing template and in situ vapor-phase polymerization route under mild conditions. The electrode made of the T-Fe 2 O 3 /PPy NAs exhibits a high areal capacitance of 382.4 mF cm -2 at a current density of 0.5 mA cm -2 and excellent reversibility. The solid-state asymmetric supercapacitor consisting of T-Fe 2 O 3 /PPy NAs and MnO 2 electrodes achieves a high energy density of 0.22 mWh cm -3 at a power density of 165.6 mW cm -3 . © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

Nutrient availability in rangeland soils: influence of prescribed burning, herbaceous vegetation removal, overseeding with Bromus tectorum, season, and elevation

Treesearch

R. R. Blank; J. Chambers; B. Roundy; A. Whittaker

2007-01-01

Soil nutrient availability influences plant invasions. Resin capsules were used to examine soil nutrient bioavailability along 2 sagebrush-grassland elevation transects in the east Tintic Range (Utah) and Shoshone Range (Nevada). In the fall of 2001, treatments were applied to 3 replicate plots at each site, which included prescribed burning, herbaceous vegetation...

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

USDA-ARS?s Scientific Manuscript database

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 ...

Predicting seed dormancy loss and germination timing for Bromus tectorum in a semi-arid environment using hydrothermal time models

Treesearch

Susan E. Meyer; Phil S. Allen

2009-01-01

A principal goal of seed germination modelling for wild species is to predict germination timing under fluctuating field conditions. We coupled our previously developed hydrothermal time, thermal and hydrothermal afterripening time, and hydration-dehydration models for dormancy loss and germination with field seed zone temperature and water potential measurements from...

Bioassay Guided Fractionation of an Anti-Methicillin-Resistant Staphylococcus aureus Flavonoid From Bromus inermis Leyss Inflorescences

PubMed Central

Aliahmadi, Atousa; Mirzajani, Fateme; Ghassempour, Alireza; Sonboli, Ali

2014-01-01

Background: Plants are considered as promising sources of new antibacterial agents as well as bioassay guided fractionation. Objectives: In the present work, the antibacterial properties, especially against methicillin-resistant Staphylococcus aureus (MRSA), of Bromus inermis inflorescence was studied, using the bioassay guided fractionation as well as the bio-autographic method. Materials and Methods: The plant organic extract was prepared via maceration in methanol, followed by the fractionation using n-hexane. The extracts were subjected for minimum inhibitory concentrations (MICs) against some human pathogenic bacteria via standard broth micro-dilution assay. Thereafter, a bio-autographical method was applied using the high performance thin layer chromatography (HPTLC) coupled with agar overlay assays for the primary characterization and identification of bioactive substance (s). Results: Through the bioassay guided fractionation method, the greatest antibacterial activities were related to the n-hexane extract. It was also revealed that the effective anti-MRSA agent of the assessed plant was a relatively polar substance with an MIC value of about 8 μg/mL against the tested MRSA strain (in comparison with the MIC value of 32 μg/mL for chloramphenicol). Conclusions: As a result of the full range UV-Vis scanning of the responsible band in the HPTLC experiments (200-700 nm), the flavonoid was the most imaginable natural compound. PMID:25741430

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.

Granivory of invasive, naturalized, and native plants in communities differentially susceptible to invasion.

PubMed

Connolly, B M; Pearson, D E; Mack, R N

2014-07-01

Seed predation is an important biotic filter that can influence abundance and spatial distributions of native species through differential effects on recruitment. This filter may also influence the relative abundance of nonnative plants within habitats and the communities' susceptibility to invasion via differences in granivore identity, abundance, and food preference. We evaluated the effect of postdispersal seed predators on the establishment of invasive, naturalized, and native species within and between adjacent forest and steppe communities of eastern Washington, USA that differ in severity of plant invasion. Seed removal from trays placed within guild-specific exclosures revealed that small mammals were the dominant seed predators in both forest and steppe. Seeds of invasive species (Bromus tectorum, Cirsium arvense) were removed significantly less than the seeds of native (Pseudoroegneria spicata, Balsamorhiza sagittata) and naturalized (Secale cereale, Centaurea cyanus) species. Seed predation limited seedling emergence and establishment in both communities in the absence of competition in a pattern reflecting natural plant abundance: S. cereale was most suppressed, B. tectorum was least suppressed, and P. spicata was suppressed at an intermediate level. Furthermore, seed predation reduced the residual seed bank for all species. Seed mass correlated with seed removal rates in the forest and their subsequent effects on plant recruitment; larger seeds were removed at higher rates than smaller seeds. Our vegetation surveys indicate higher densities and canopy cover of nonnative species occur in the steppe compared with the forest understory, suggesting the steppe may be more susceptible to invasion. Seed predation alone, however, did not result in significant differences in establishment for any species between these communities, presumably due to similar total small-mammal abundance between communities. Consequently, preferential seed predation by small

U.S. Geological Survey Science for the Wyoming Landscape Conservation Initiative-2010 Annual Report

USGS Publications Warehouse

Bowen, Zachary H.; Aldridge, Cameron L.; Anderson, Patrick J.; Assal, Timothy J.; Biewick, Laura; Blecker, Steven W.; Boughton, Gregory K.; Bristol, R. Sky; Carr, Natasha B.; Chalfoun, Anna D.; Chong, Geneva W.; Clark, Melanie L.; Diffendorfer, Jay E.; Fedy, Bradley C.; Foster, Katharine; Garman, Steven L.; Germaine, Stephen S.; Holloway, JoAnn; Homer, Collin G.; Kauffman, Matthew J.; Keinath, Douglas; Latysh, Natalie; Manier, Daniel J.; McDougal, Robert R.; Melcher, Cynthia P.; Miller, Kirk A.; Montag, Jessica; Potter, Christopher J.; Schell, Spencer; Shafer, Sarah L.; Smith, David B.; Stillings, Lisa L.; Tuttle, Michele L.W.; Wilson, Anna B.

2011-01-01

the Moxa Arch Natural Gas Development area) and (2) the study of cheatgrass (Bromus tectorum) occurrence in burn treatments of the Little Mountain Ecosystem. The activity that entails evaluating relationships between ungulate herbivory and fire on aspen (Populus tremuloides) recruitment also was expanded to include relationships between stand characteristics of and herbivory on aspen in various ecohydrological settings. The USGS continued compiling data and developing geospatial products from all of its WLCI activities to support (1) ranking and prioritizing of proposed conservation projects, (2) developing the WLCI Integrated Assessment, and (3) developing the WLCI 5-year Conservation Action Plan. Two activities were completed in FY2010: (1) the conceptual modeling and indicator selection for monitoring resource conditions across the WLCI region, and (2) the literature review on effects of oil and gas development in western regions of the United States, both of which are in the last stages of publication.

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.

Variation in the establishment of a non-native annual grass influences competitive interactions with Mojave Desert perennials

USGS Publications Warehouse

DeFalco, L.A.; Fernandez, G.C.J.; Nowak, R.S.

2007-01-01

Competition between native and non-native species can change the composition and structure of plant communities, but in deserts, the highly variable timing of resource availability also influences non-native plant establishment, thus modulating their impacts on native species. In a field experiment, we varied densities of the non-native annual grass Bromus madritensis ssp. rubens around individuals of three native Mojave Desert perennials-Larrea tridentata, Achnatherum hymenoides, and Pleuraphis rigida-in either winter or spring. For comparison, additional plots were prepared for the same perennial species and seasons, but with a mixture of native annual species as neighbors. Growth of perennials declined when Bromus was established in winter because Bromus stands had 2-3 months of growth and high water use before perennial growth began. However, water potentials for the perennials were not significantly reduced, suggesting that direct competition for water may not be the major mechanism driving reduced perennial growth. The impact of Bromus on Larrea was lower than for the two perennial grasses, likely because Larrea maintains low growth rates throughout the year, even after Bromus has completed its life cycle. This result contrasts with the perennial grasses, whose phenology completely overlaps with (Achnatherum) or closely follows (Pleuraphis) that of Bromus. In comparison, Bromus plants established in spring were smaller than those established in winter and thus did not effectively reduce growth of the perennials. Growth of perennials with mixed annuals as neighbors also did not differ from those with Bromus neighbors of equivalent biomass, but stands of these native annuals did not achieve the high biomass of Bromus stands that were necessary to reduce perennial growth. Seed dormancy and narrow requirements for seedling survivorship of native annuals produce densities and biomass lower than those achieved by Bromus; thus, impacts of native Mojave Desert

Soil nitrogen mineralization not affected by grass species traits

Treesearch

Maged Ikram Nosshi; Jack Butler; M. J. Trlica

2007-01-01

Species N use traits was evaluated as a mechanism whereby Bromus inermis (Bromus), an established invasive, might alter soil N supply in a Northern mixed-grass prairie. We compared soils under stands of Bromus with those from three representative native grasses of different litter C/N: Andropogon...

Interaction of historical and nonhistorical disturbances maintains native plant communities.

PubMed

Davies, K W; Svejcar, T J; Bates, J D

2009-09-01

Historical disturbance regimes are often considered a critical element in maintaining native plant communities. However, the response of plant communities to disturbance may be fundamentally altered as a consequence of invasive plants, climate change, or prior disturbances. The appropriateness of historical disturbance patterns under modern conditions and the interactions among disturbances are issues that ecologists must address to protect and restore native plant communities. We evaluated the response of Artemisia tridentata ssp. wyomingensis (Beetle & A. Young) S.L. Welsh plant communities to their historical disturbance regime compared to other disturbance regimes. The historical disturbance regime of these plant communities was periodic fires with minimal grazing by large herbivores. We also investigated the influence of prior disturbance (grazing) on the response of these communities to subsequent disturbance (burning). Treatments were: (1) ungrazed (livestock grazing excluded since 1936) and unburned, (2) grazed and unburned, (3) ungrazed and burned (burned in 1993), and (4) grazed and burned. The ungrazed-burned treatment emulated the historical disturbance regime. Vegetation cover, density, and biomass production were measured the 12th, 13th, and 14th year post-burning. Prior to burning the presence of Bromus tectorum L., an exotic annual grass, was minimal (<0.5% cover), and vegetation characteristics were similar between grazed and ungrazed treatments. However, litter accumulation was almost twofold greater in ungrazed than in grazed treatments. Long-term grazing exclusion followed by burning resulted in a substantial B. tectorum invasion, but burning the grazed areas did not produce an invasion. The ungrazed-burned treatment also had less perennial vegetation than other treatments. The accumulation of litter (fuel) in ungrazed treatments may have resulted in greater fire-induced mortality of perennial vegetation in ungrazed compared to grazed treatments

Fire Impacts on the Mojave Desert Ecosystem: Literature Review

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fenstermaker Lynn

2012-01-01

The Nevada National Security Site (NNSS) is located within the Mojave Desert, which is the driest region in North America. Precipitation on the NNSS varies from an annual average of 130 millimeters (mm; 5.1 inches) with a minimum of 47 mm (1.9 inches) and maximum of 328 mm (12.9 inches) over the past 15 year period to an annual average of 205 mm (8.1 inches) with an annual minimum of 89 mm (3.5 inches) and maximum of 391 mm (15.4 inches) for the same time period; for a Frenchman Flat location at 970 meters (m; 3182 feet) and a Pahutemore » Mesa location at 1986 m (6516 feet), respectively. The combination of aridity and temperature extremes has resulted in sparsely vegetated basins (desert shrub plant communities) to moderately vegetated mountains (mixed coniferous forest plant communities); both plant density and precipitation increase with increasing elevation. Whereas some plant communities have evolved under fire regimes and are dependent upon fire for seed germination, plant communities within the Mojave Desert are not dependent on a fire regime and therefore are highly impacted by fire (Brown and Minnich, 1986; Brooks, 1999). As noted by Johansen (2003) natural range fires are not prevalent in the Mojave and Sonoran Deserts because there is not enough vegetation present (too many shrub interspaces) to sustain a fire. Fire research and hence publications addressing fires in the Southwestern United States (U.S.) have therefore focused on forest, shrub-steppe and grassland fires caused by both natural and anthropogenic ignition sources. In the last few decades, however, invasion of mid-elevation shrublands by non-native Bromus madritensis ssp. rubens and Bromus tectorum (Hunter, 1991) have been highly correlated with increased fire frequency (Brooks and Berry, 2006; Brooks and Matchett, 2006). Coupled with the impact of climate change, which has already been shown to be playing a role in increased forest fires (Westerling et al., 2006), it is likely that the

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.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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 themore » 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.« less

[Floral structure of two species of Trachycarpea (Arecaceae)].

PubMed

Guevara, Lorena I; Jáuregui, Damelis J; Stauffer, Fred W

2014-09-01

Copernicia and Washingtonia are two genera of the Trachycarpeae for which no subtribal classification has been proposed, mainly because of the lack of resolution in phylogenetic studies. Morphology and anatomy of flowers whithin Coryphoideae have proven useful for taxa delimitation and supporting relationships among their members. A description of the morphological and anatomical structure of flowers of C. tectorum and W. filifera is presented in order to explore reproductive characters that may clarify their classification within the subfamily and to contribute with floral biology studies. Flowers of cultivated specimens of both taxa and developing fruits of C. tectorum were fixed in FAA, dissected for morphological analysis, and parafin-embedded flowers and fruits were serially sectioned for obtaining permanent slides, using conventional techniques and safranin-fast green staining. All procedures were carried out in the Laboratory of Morpho-Anatomy, Agronomy Faculty of the Universidad Central de Venezuela (UCV). Both species have hermaphroditic flowers. C. tectorum flowers have a thick and pubescent perianth, six stamens with filaments forming a tube fused to the corolla, with rounded projections and an acute apex where the anthers are inserted. W. filifera flowers have an irregularly dentate calyx, and a shortly acuminate corolla, six stamens united by their filaments to the corolla which at the same time are briefly fused to the gynoecium. Cells with druse crystals in the staminal tube are reported for C. tectorum. Only one of the carpels of the gynoecium of C. tectorum develops at fruit stage, and a layer of abundant raphide cells forming a crustaceous endocarp in mature fruits, was found. W. filifera presents the perianth mesophyll with few layers of thick walled cells and schlerenchymatic tissue, gynoecium with apically fused carpels in the ventral region of ovary, free at the base and the apex of the style, where the ventral sutures are opened. C. tectorum

Secondary invasions of noxious weeds associated with control of invasive Tamarix are frequent, idiosyncratic and persistent

USGS Publications Warehouse

González, Eduardo; Sher, Anna A.; Anderson, Robert M.; Bay, Robin F.; Bean, Daniel W.; Bissonnete, Gabriel J.; Cooper, David J.; Dohrenwend, Kara; Eichhorst, Kim D.; El Waer, Hisham; Kennard, Deborah K.; Harms-Weissinger, Rebecca; Henry, Annie L.; Makarick, Lori J.; Ostoja, Steven M.; Reynolds, Lindsay V.; Robinson, W. Wright; Shafroth, Patrick B.; Tabacchi, Erich

2017-01-01

Control of invasive species within ecosystems may induce secondary invasions of non-target invaders replacing the first alien. We used four plant species listed as noxious by local authorities in riparian systems to discern whether 1) the severity of these secondary invasions was related to the control method applied to the first alien; and 2) which species that were secondary invaders persisted over time. In a collaborative study by 16 research institutions, we monitored plant species composition following control of non-native Tamarix trees along southwestern U.S. rivers using defoliation by an introduced biocontrol beetle, and three physical removal methods: mechanical using saws, heavy machinery, and burning in 244 treated and 79 untreated sites across six U.S. states. Physical removal favored secondary invasions immediately after Tamarix removal (0–3 yrs.), while in the biocontrol treatment, secondary invasions manifested later (> 5 yrs.). Within this general trend, the response of weeds to control was idiosyncratic; dependent on treatment type and invader. Two annual tumbleweeds that only reproduce by seed (Bassia scoparia and Salsola tragus) peaked immediately after physical Tamarix removal and persisted over time, even after herbicide application. Acroptilon repens, a perennial forb that vigorously reproduces by rhizomes, and Bromus tectorum, a very frequent annual grass before removal that only reproduces by seed, were most successful at biocontrol sites, and progressively spread as the canopy layer opened. These results demonstrate that strategies to control Tamarix affect secondary invasions differently among species and that time since disturbance is an important, generally overlooked, factor affecting response.

Plastic responses of native plant root systems to the presence of an invasive annual grass.

PubMed

Phillips, Allison J; Leger, Elizabeth A

2015-01-01

• The ability to respond to environmental change via phenotypic plasticity may be important for plants experiencing disturbances such as climate change and plant invasion. Responding to belowground competition through root plasticity may allow native plants to persist in highly invaded systems such as the cold deserts of the Intermountain West, USA.• We investigated whether Poa secunda, a native bunchgrass, could alter root morphology in response to nutrient availability and the presence of a competitive annual grass. Seeds from 20 families were grown with high and low nutrients and harvested after 50 d, and seeds from 48 families, grown with and without Bromus tectorum, were harvested after ∼2 or 6 mo. We measured total biomass, root mass fraction, specific root length (SRL), root tips, allocation to roots of varying diameter, and plasticity in allocation.• Plants had many parallel responses to low nutrients and competition, including increased root tip production, a trait associated with tolerance to reduced resources, though families differed in almost every trait and correlations among trait changes varied among experiments, indicating flexibility in plant responses. Seedlings actively increased SRL and fine root allocation under competition, while older seedlings also increased coarse root allocation, a trait associated with increased tolerance, and increased root mass fraction.• The high degree of genetic variation for root plasticity within natural populations could aid in the long-term persistence of P. secunda because phenotypic plasticity may allow native species to persist in invaded and fluctuating resource environments. © 2015 Botanical Society of America, Inc.

Altered snowfall and soil disturbance influence the early life stage transitions and recruitment of a native and invasive grass in a cold desert.

PubMed

Gornish, Elise S; Aanderud, Zachary T; Sheley, Roger L; Rinella, Mathew J; Svejcar, Tony; Englund, Suzanne D; James, Jeremy J

2015-02-01

Climate change effects on plants are expected to be primarily mediated through early life stage transitions. Snowfall variability, in particular, may have profound impacts on seedling recruitment, structuring plant populations and communities, especially in mid-latitude systems. These water-limited and frequently invaded environments experience tremendous variation in snowfall, and species in these systems must contend with harsh winter conditions and frequent disturbance. In this study, we examined the mechanisms driving the effects of snowpack depth and soil disturbance on the germination, emergence, and establishment of the native Pseudoroegnaria spicata and the invasive Bromus tectorum, two grass species that are widely distributed across the cold deserts of North America. The absence of snow in winter exposed seeds to an increased frequency and intensity of freeze-thaw cycles and greater fungal pathogen infection. A shallower snowpack promoted the formation of a frozen surface crust, reducing the emergence of both species (more so for P. spicata). Conversely, a deeper snowpack recharged the soil and improved seedling establishment of both species by creating higher and more stable levels of soil moisture availability following spring thaw. Across several snow treatments, experimental disturbance served to decrease the cumulative survival of both species. Furthermore, we observed that, regardless of snowpack treatment, most seed mortality (70-80%) occurred between seed germination and seedling emergence (November-March), suggesting that other wintertime factors or just winter conditions in general limited survival. Our results suggest that snowpack variation and legacy effects of the snowpack influence emergence and establishment but might not facilitate invasion of cold deserts.

Annual grass invasion in sagebrush-steppe: The relative importance of climate, soil properties and biotic interactions

USGS Publications Warehouse

Bansal, Sheel; Sheley, Roger L.

2016-01-01

The invasion by winter-annual grasses (AGs) such as Bromus tectorum into sagebrush steppe throughout the western USA is a classic example of a biological invasion with multiple, interacting climate, soil and biotic factors driving the invasion, although few studies have examined all components together. Across a 6000-km2 area of the northern Great Basin, we conducted a field assessment of 100 climate, soil, and biotic (functional group abundances, diversity) factors at each of 90 sites that spanned an invasion gradient ranging from 0 to 100 % AG cover. We first determined which biotic and abiotic factors had the strongest correlative relationships with AGs and each resident functional group. We then used regression and structural equation modeling to explore how multiple ecological factors interact to influence AG abundance. Among biotic interactions, we observed negative relationships between AGs and biodiversity, perennial grass cover, resident species richness, biological soil crust cover and shrub density, whereas perennial and annual forb cover, tree cover and soil microbial biomass had no direct linkage to AG. Among abiotic factors, AG cover was strongly related to climate (increasing cover with increasing temperature and aridity), but had weak relationships with soil factors. Our structural equation model showed negative effects of perennial grasses and biodiversity on AG cover while integrating the negative effects of warmer climate and positive influence of belowground processes on resident functional groups. Our findings illustrate the relative importance of biotic interactions and climate on invasive abundance, while soil properties appear to have stronger relationships with resident biota than with invasives.

DESI-Detection of early-season invasives (software-installation manual and user's guide version 1.0)

USGS Publications Warehouse

Kokaly, Raymond F.

2011-01-01

This report describes a software system for detecting early-season invasive plant species, such as cheatgrass. The report includes instructions for installing the software and serves as a user's guide in processing Landsat satellite remote sensing data to map the distributions of cheatgrass and other early-season invasive plants. The software was developed for application to the semi-arid regions of southern Utah; however, the detection parameters can be altered by the user for application to other areas.

GISD

Science.gov Websites

GISD Global invasive species database Home About the GISD How to use Contacts 100 of the worst ) Bromus rubens Line drawing of Bromus rubens (USDA-NRCS PLANTS Database / Hitchcock, A.S. (rev. A. Chase GISD ISPRA SNPA The Global Invasive Species Database was developed and is managed by the Invasive

Final Programmatic Environmental Assessment: Demolition and Abandonment of Atlas and Titan Facilities Vandenberg Air Force Base, California

DTIC Science & Technology

2005-09-13

in the area, with black mustard, common sowthistle ( Sonchus oleraceus ), iceplant, ripgut brome (Bromus diandrus), bur clover, and foxtail barley...dominant species are Brassica nigra, Sonchus oleraceus , Carpobrotus edulis, Bromus diandrus, Medicago polymorpha and Hordeum murinum. Demolition...multiflorum, Melotis indicus, Plantago coronopus, and Sonchus oleraceus . Survey for birds in interior prior to start of nesting (February), and exclusion if

The effect of rodent seed predation on four species of California annual grasses.

PubMed

Borchert, M I; Jain, S K

1978-01-01

The effect of seed predation by Microtus californicus and Mus musculus on plant numbers of four species of California annual grasses was investigated for one year period on a grassland near Davis, California. In winter, mice utilized dead star thistle plants for cover when grasses in open areas were short, but moved into open areas when grass grew tall in spring.Using exclosures and plots sown with known quantities of seed, it was estimated that a mouse population (approximate density 120/acre) consumed 75% of Avena fatua seed, 44% of Hordeum leporinum seed, and 37% of Bromus diandrus seed. Mice showed a strong preference for Avena seed.Plant numbers of Avena and Hordeum were reduced by 62% and 30%, respectively. Hordeum, Lolium, and to a lesser extent, Bromus responded to a competitive release from Avena by increases in plant size and reproductive output. In addition, seed predation markedly increased seed to adult plant survivorship of Avena, Hordeum, and Bromus.Vertebrate seed predation is discussed as a potentially important factor in the yearly patterns of plant population regulation in California annual grasslands.

The indirect effects of cheatgrass invasion: Grasshopper herbivory on native grasses determined by neighboring cheatgrass abundance

Treesearch

Julie Beckstead; Susan E. Meyer; Carol K. Augsperger

2008-01-01

Invasion biology has focused on the direct effects of plant invasion and has generally overlooked indirect interactions. Here we link theories of invasion biology and herbivory to explore an indirect effect of one invading species on associational herbivory (the effect of neighboring plants on herbivory) of native species. We studied a Great Basin shadscale (...

Plant rhizosphere species-specific stoichiometry and regulation of extracellular enzyme and microbial community structure

NASA Astrophysics Data System (ADS)

Bell, C. W.; Calderon, F.; Pendall, E.; Wallenstein, M. D.

2012-12-01

Plant communities affect the activity and composition of soil microbial communities through alteration of the soil environment during root growth; substrate availability through root exudation; nutrient availability through plant uptake; and moisture regimes through transpiration. As a result, positive feedbacks in soil properties can result from alterations in microbial community composition and function in the rhizosphere zone. At the ecosystem-scale, many properties of soil microbial communities can vary between forest stands dominated by different species, including community composition and stoichiometry. However, the influence of smaller individual plants on grassland soils and microbial communities is less well documented. There is evidence to suggest that some plants can modify their soil environment in a manner that favors their persistence. For example, when Bromus tectorum plants invade, soil microbial communities tend to have higher N mineralization rates (in the rhizosphere zone) relative to native plants. If tight linkages between individual plant species and microbial communities inhabiting the rhizosphere exist, we hypothesized that any differences among plant species specific rhizosphere zones could be observed by shifts in: 1) soil -rhizosphere microbial community structure, 2) enzymatic C:N:P acquisition activities, 3) alterations in the soil C chemistry composition in the rhizosphere, and 4) plant - soil - microbial C:N:P elemental stoichiometry. We selected and grew 4 different C3 grasses species including three species native to the Shortgrass Steppe region (Pascopyrum smithii, Koeleria macrantha, and Vulpia octoflora) and one exotic invasive plant species (B. tectorum) in root-boxes that are designed to allow for easy access to the rhizosphere. The field soil was homogenized using a 4mm sieve and mixed 1:1 with sterile sand and seeded as monocultures (24 replicate root - boxes for each species). Plant and soil samples (along with no - plant

DOE Office of Scientific and Technical Information (OSTI.GOV)

FOGWELL, T.W.

During the biological survey and inventory of the Hanford Site conducted in the mid-1990s (1995 and 1996), preliminary surveys of the riparian vegetation were conducted along the Hanford Reach. These preliminary data were reported to The Nature Conservancy (TNC), but were not included in any TNC reports to DOE or stakeholders. During the latter part of FY2001, PNNL contracted with SEE Botanical, the parties that performed the original surveys in the mid 1990s, to complete the data summaries and mapping associated with the earlier survey data. Those data sets were delivered to PNNL and the riparian mapping by vegetation typemore » for the Hanford Reach is being digitized during the first quarter of FY2002. These mapping efforts provide the information necessary to create subsequent spatial data layers to describe the riparian zone according to plant functional types (trees, shrubs, grasses, sedges, forbs). Quantification of the riparian zone by vegetation types is important to a number of DOE'S priority issues including modeling contaminant transport and uptake in the near-riverine environment and the determination of ecological risk. This work included the identification of vegetative zones along the Reach by changes in dominant plant species covering the shoreline from just to the north of the 300 Area to China Bar near Vernita. Dominant and indicator species included Agropyron dasytachyudA. smithii, Apocynum cannabinum, Aristida longiseta, Artemisia campestris ssp. borealis var scouleriana, Artemisa dracunculus, Artemisia lindleyana, Artemisia tridentata, Bromus tectorum, Chrysothamnus nauseosus, Coreopsis atkinsoniana. Eleocharis palustris, Elymus cinereus, Equisetum hyemale, Eriogonum compositum, Juniperus trichocarpa, Phalaris arundinacea, Poa compressa. Salk exigua, Scirpus acutus, Solidago occidentalis, Sporobolus asper,and Sporobolus cryptandrus. This letter report documents the data received, the processing by PNNL staff, and additional data gathered in

Twelve invasive plant taxa in U.S. western riparian ecosystems

EPA Science Inventory

Assessments of stream ecosystems often include an evaluation of riparian condition; a key stressor in riparian ecosystems is the presence of invasive plants. We analyzed the distribution of 12 invasive taxa (common burdock [Arctium minus], giant reed [Arundo donax], cheatgrass [B...

Putting resilience and resistance concepts into practice

Treesearch

Jeanne C. Chambers; Jeremy D. Maestas; Mike Pellant

2015-01-01

Land managers are increasingly interested in improving resilience to disturbances, such as wildfire, and resistance to invasive species, such as cheatgrass and medusahead. This factsheet is designed to assist land managers in using resilience and resistance concepts to assess risks, prioritize management activities, and select appropriate treatments.

State-and-transition models: Conceptual versus simulation perspectives, usefulness and breadth of use, and land management applications

USGS Publications Warehouse

Provencher, Louis; Frid, Leonardo; Czembor, Christina; Morisette, Jeffrey T.

2016-01-01

State-and-Transition Simulation Modeling (STSM) is a quantitative analysis method that can consolidate a wide array of resource management issues under a “what-if” scenario exercise. STSM can be seen as an ensemble of models, such as climate models, ecological models, and economic models that incorporate human dimensions and management options. This chapter presents STSM as a tool to help synthesize information on social–ecological systems and to investigate some of the management issues associated with exotic annual Bromus species, which have been described elsewhere in this book. Definitions, terminology, and perspectives on conceptual and computer-simulated stochastic state-and-transition models are given first, followed by a brief review of past STSM studies relevant to the management of Bromus species. A detailed case study illustrates the usefulness of STSM for land management. As a whole, this chapter is intended to demonstrate how STSM can help both managers and scientists: (a) determine efficient resource allocation for monitoring nonnative grasses; (b) evaluate sources of uncertainty in model simulation results involving expert opinion, and their consequences for management decisions; and (c) provide insight into the consequences of predicted local climate change effects on ecological systems invaded by exotic annual Bromus species.

Effects of storage temperature on the physiological characteristics and vegetative propagation of desiccation-tolerant mosses

NASA Astrophysics Data System (ADS)

Guo, Yuewei; Zhao, Yunge

2018-02-01

Mosses, as major components of later successional biological soil crusts (biocrusts), play many critical roles in arid and semiarid ecosystems. Recently, some species of desiccation-tolerant mosses have been artificially cultured with the aim of accelerating the recovery of biocrusts. Revealing the factors that influence the vegetative propagation of mosses, which is an important reproductive mode of mosses in dry habitats, will benefit the restoration of moss crusts. In this study, three air-dried desiccation-tolerant mosses (Barbula unguiculata, Didymodon vinealis, and Didymodon tectorum) were hermetically sealed and stored at five temperature levels (0, 4, 17, 25, and 30 °C) for 40 days. Then, the vegetative propagation and physiological characteristics of the three mosses were investigated to determine the influence of storage temperature on the vegetative propagation of desiccation-tolerant mosses and the mechanism. The results showed that the vegetative propagation of the three mosses varied with temperature. The most variation in vegetative propagation among storage temperatures was observed in D. tectorum, followed by the variation observed in B. unguiculata. In contrast, no significant difference in propagation among temperatures was found in D. vinealis. The regenerative capacity of the three mosses increased with increasing temperature from 0 to 17 °C, accompanied by a decrease in malondialdehyde (MDA) content, and decreased thereafter. As the temperature increased, the chlorophyll and soluble protein contents increased in B. unguiculata but decreased in D. vinealis and D. tectorum. As to storage, the MDA and soluble sugar contents increased after storage. The MDA content of the three mosses increased at each of the investigated temperatures by more than 50 % from the initial values, and the soluble sugar content became higher than before in the three mosses. The integrity of cells and cell membranes is likely the most important factor influencing the

Capabilities of Seven Species of Aquatic Macrophytes for Phytoremediation of Pentachlorophenol Contaminated Sediment

NASA Astrophysics Data System (ADS)

Zhao, Liangyuan; Guo, Weijie; Li, Qingyun; Li, Huan; Zhao, Weihua; Cao, Xiaohuan

2017-01-01

Sediments are regarded as the ultimate sink of pentachlorophenol(PCP) in aquatic environment, and capabilities of seven species of aquatic macrophytes for remediating PCP contaminated sediment were investigated. Seven species of aquatic macrophytes could significantly accelerate the degradation of PCP in sediments. Among all, canna indica L., Acorus calamus L. and Iris tectorum Maxim. can be used as efficient alternative plants for remediation of PCP contaminated sediment, which attained 98%, 92% and 88% of PCP removal in sediments, respectively. PCP was detected only in root tissues and the uptake was closely related to the root lipid contents of seven plants. The presence of seven aquatic macrophytes significantly increased microbial populations and the activities of dehydrogenase compared with control sediments, indicating that rhizosphere microorganism played important role in the remediation process. In conclusion, seven species of aquatic macrophytes may act as promising tools for the PCP phytoremediation in aquatic environment, especially Canna indica L., Acorus calamus L. and Iris tectorum Maxim.

Seasonal neighbors: residential development encroaches on mule deer winter range in central Oregon

Treesearch

Marie Oliver; Jeff Kline

2012-01-01

Mule deer populations in central Oregon are in decline, largely because of habitat loss. Several factors are likely contributors. Encroaching juniper and invasive cheatgrass are replacing deer forage with high nutritional value, such as bitterbrush and sagebrush. Fire suppression and reduced timber harvests mean fewer acres of early successional forest, which also...

Diets of black-tailed hares on the Hanford Reservation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Uresk, D.W.; Cline, J.F.; Rickard, W.H.

1975-04-01

A fecal pellet analyses showed that black-tailed hares (jackrabbits) were selective in plants chosen as food. The most abundant herbaceous plant, cheatgrass, was not found in the pellets. Sagebrush and bitterbrush, woody plants, were not an important part of the hares' diet. Forbs, rabbitbrush, and certain grass species were preferred foods. (auth)

Greater sage-grouse as an umbrella species for sagebrush-associated vertebrates.

Treesearch

Mary M. Rowland; Michael J. Wisdom; Lowell Suring; Cara W. Meinke

2006-01-01

Widespread degradation of the sagebrush ecosystem in the western United States, including the invasion of cheatgrass, has prompted resource managers to consider a variety of approaches to restore and conserve habitats for sagebrush-associated species. One such approach involves the use of greater sage-grouse, a species of prominent conservation interest, as an umbrella...

'Umatilla' snow buckwheat for rangeland restoration in the interior Pacific Northwest

Treesearch

A. R. Tiedemann; S. M. Lambert; J. R. Carlson; C. J. Perry; N. L. Shaw; B. L. Welch; C. H. Driver

1997-01-01

Native plants are generally considered the best option for plant materials to restore productivity and diversity to degraded rangelands (McArthur 1988). It is difficult to find native plants capable of becoming established from seed in dense stands of introduced annual species such as cheatgrass. It has been easier to import species such as crested wheatgrass to...

Maintenance Dredging & Confined Disposal Facility for the Crooked River Portion of Michigan’s Inland Route and the Operation, Maintenance, & Proposed Public Use Facilities for the Alanson Lock and Weir, Michigan.

DTIC Science & Technology

1980-01-01

Dwarf lake iris, threatened. Calypso bulbosa, Calypso or Fairy - slipper , threatened. Cypripedium aietinum, Ram’s head lady- slipper , rare. Orchis...rotundifolia, Round-leaved orchid , threatened. Agropyron dasystachyum, threatened. Beckmannia syzigachne, Slough grass, threatened. Bromus pumpellianus

Assessing the risk of nitrogen deposition to natural resources in the Four Corners area

USGS Publications Warehouse

Reed, Sasha C.; Belnap, Jayne; Floyd-Hanna, Lisa; Crews, Tim; Herring, Jack; Hanna, Dave; Miller, Mark E.; Duniway, Michael C.; Roybal, Carla M.

2013-01-01

the approach utilized here (e.g., we have fertilization plots to explore how N deposition affects Bromus tectorum invasion that will surely yield provoking results), we plan to continue this exciting line of questioning and expect further insight to be forthcoming.

Long-term response of a Mojave Desert winter annual plant community to a whole-ecosystem atmospheric CO2 manipulation (FACE).

PubMed

Smith, Stanley D; Charlet, Therese N; Zitzer, Stephen F; Abella, Scott R; Vanier, Cheryl H; Huxman, Travis E

2014-03-01

Desert annuals are a critically important component of desert communities and may be particularly responsive to increasing atmospheric (CO2 ) because of their high potential growth rates and flexible phenology. During the 10-year life of the Nevada Desert FACE (free-air CO2 enrichment) Facility, we evaluated the productivity, reproductive allocation, and community structure of annuals in response to long-term elevated (CO2 ) exposure. The dominant forb and grass species exhibited accelerated phenology, increased size, and higher reproduction at elevated (CO2 ) in a wet El Niño year near the beginning of the experiment. However, a multiyear dry cycle resulted in no increases in productivity or reproductive allocation for the remainder of the experiment. At the community level, early indications of increased dominance of the invasive Bromus rubens at elevated (CO2 ) gave way to an absence of Bromus in the community during a drought cycle, with a resurgence late in the experiment in response to higher rainfall and a corresponding high density of Bromus in a final soil seed bank analysis, particularly at elevated (CO2 ). This long-term experiment resulted in two primary conclusions: (i) elevated (CO2 ) does not increase productivity of annuals in most years; and (ii) relative stimulation of invasive grasses will likely depend on future precipitation, with a wetter climate favoring invasive grasses but currently predicted greater aridity favoring native dicots. © 2013 John Wiley & Sons Ltd.

Sagebrush in western North America: habitats and species in jeopardy.

Treesearch

Jonathan Thompson

2007-01-01

Sagebrush habitats are declining rapidly across western North America, with over 350 associated plant and animal species at risk of local or regional extirpation. The sagebrush ecosystem is one of the largest in the United States, and it is vulnerable to a litany of threats. Chief among them is invasion of cheatgrass into the understory, followed by high-severity fires...

Green strips or vegetative fuel breaks

Treesearch

Loren St. John; Dan Ogle

2009-01-01

According to the National Interagency Fire Center, between 1998 and 2008 there were on average 65,581 fires per year and an average of 6,114,135 acres burned each year in the United States. Rangelands in the western United States have been invaded by many annual weed species including cheatgrass, an introduced winter annual grass that produces large quantities of...

Beneficial effects of neotyphodium tembladerae and neotyphodium pampeanum on a wild forage grass

USDA-ARS?s Scientific Manuscript database

Asexual, vertically transmitted fungal endophytes of the genus Neotyphodium are considered to enhance growth, stress resistance and competitiveness of agronomic grasses, but have been suggested to have neutral or deleterious effects on wild grasses. We studied whether the associations between Bromus...

Beneficial effects of Neotyphodium tembladerae and Neotyphodium pampeanum on a wild forage grass

USDA-ARS?s Scientific Manuscript database

Asexual, vertically transmitted fungal endophytes of the genus Neotyphodium are considered to enhance growth, stress resistance and competitiveness of agronomic grasses, but have been suggested to have neutral or deleterious effects on wild grasses. We studied whether the associations between Bromus...

STOCKPILED PRAIRIEGRASS PROVIDES HIGH-QUALITY FALL GRAZING FOR LAMBS

USDA-ARS?s Scientific Manuscript database

New varieties of prairiegrass (Bromus catharticus Vahl. = B. willdenowii Kunth.) exhibit improved persistence over ‘Matua’ under USA growing conditions, but animal performance data is lacking. We evaluated performance of lambs grazing stockpiled ‘Dixon’ prairiegrass on West Virginia hill pasture in...

Germination timing and rate of locally collected western wheatgrass and smooth brome grass: the role of collection site and light sensitivity along a riparian corridor

USDA-ARS?s Scientific Manuscript database

The ecological integrity of riparian areas is reduced by biological plant invaders like smooth brome grass (Bromus inermis). Smooth brome actively invades recently disturbed riparian zones by its high seed production and fast seedling establishment. Restoring native perennial grasses to these regio...

The effects of increased CO[sub 2] on the competitive ability of Lupinus arboreus, a dominant nitrogen-fixing shrub

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wallace, A.M.

Plant responses to increased atmospheric CO[sub 2] have been shown to be both species-specific and dependent on other environmental factors, potentially changing competitive interactions and altering community structure. The competitive response of a dominant nitrogen-fixing shrub to an introduced annual (Bromus diandrus) and a native perennial grass (Bromus carinatus) was measured under ambient and high CO[sub 2] and two nitrogen levels. These species coexist in a generally nitrogen-limited coastal grassland reserve besieged with alien species. The relative competitive ability of the lupin increased with CO[sub 2] for all treatments, with the largest difference occurring at low nitrogen in competition withmore » the introduced annual. This study provides a global change perspective for those interested in conserving native Californian grassland species, as well as the first data on the competitive response of nitrogen-fixers to high CO[sub 2].« less

Soil modification by invasive plants: Effects on native and invasive species of mixed-grass prairies

USGS Publications Warehouse

Jordan, N.R.; Larson, D.L.; Huerd, S.C.

2008-01-01

Invasive plants are capable of modifying attributes of soil to facilitate further invasion by conspecifics and other invasive species. We assessed this capability in three important plant invaders of grasslands in the Great Plains region of North America: leafy spurge (Euphorbia esula), smooth brome (Bromus inermis) and crested wheatgrass (Agropyron cristatum). In a glasshouse, these three invasives or a group of native species were grown separately through three cycles of growth and soil conditioning in both steam-pasteurized and non-pasteurized soils, after which we assessed seedling growth in these soils. Two of the three invasive species, Bromus and Agropyron, exhibited significant self-facilitation via soil modification. Bromus and Agropyron also had significant facilitative effects on other invasives via soil modification, while Euphorbia had significant antagonistic effects on the other invasives. Both Agropyron and Euphorbia consistently suppressed growth of two of three native forbs, while three native grasses were generally less affected. Almost all intra- and interspecific effects of invasive soil conditioning were dependent upon presence of soil biota from field sites where these species were successful invaders. Overall, these results suggest that that invasive modification of soil microbiota can facilitate plant invasion directly or via 'cross-facilitation' of other invasive species, and moreover has potential to impede restoration of native communities after removal of an invasive species. However, certain native species that are relatively insensitive to altered soil biota (as we observed in the case of the forb Linum lewisii and the native grasses), may be valuable as 'nurse'species in restoration efforts. ?? 2007 Springer Science+Business Media B.V.

Ecotoxicological study of arsenic and lead contaminated soils in former orchards at the Hanford Site, USA.

PubMed

Delistraty, Damon; Yokel, Jerry

2014-01-01

The purpose of this study was to assess ecotoxicity of former orchard soils contaminated with lead arsenate pesticides at the Hanford Site in Washington state (USA). Surface soil, plant, and invertebrate samples were collected from 11 sites in former orchard areas. Mean (standard deviation [SD]) for As and Pb in soil were 39.5 (40.6) and 208 (142) mg/kg dry wt, respectively (n = 11). These concentrations exceeded Hanford background levels but were similar to orchard soils elsewhere. In our study, As and Pb soil concentrations were positively and significantly correlated (r = 0.87, Bonferroni P < 0.05). Speciation of total inorganic As in soil (n = 6) demonstrated that As+5 was the dominant form (>99%). Mean (SD) for As and Pb in cheatgrass were 3.9 (7.9) and 12.4 (20.0) mg/kg dry wt, respectively (n = 11), while mean (SD) for As and Pb in darkling beetles were 5.4 (2.6) and 3.9 (3.0) mg/kg dry wt, respectively (n = 8). Linear regressions were constructed to estimate soil to cheatgrass and soil to darkling beetle uptake for As and Pb. These were significant (Bonferroni P < 0.05) only for cheatgrass versus soil (As) and darkling beetle versus soil (Pb). Standardized lettuce seedling and earthworm bioassays were performed with a subset of soil samples (n = 6). No significant effects (P > 0.05) were observed in lettuce survival or growth nor in earthworm survival or sublethal effects. Based on these bioassays, unbounded no observed effect concentrations (NOECs) in soil for As and Pb were 128 and 390 mg/kg dry wt, respectively. However, our range of soil concentrations generally overlapped a set of ecotoxicological benchmarks reported in the literature. Given uncertainty and limited sampling related to our NOECs, as well as uncertainty in generic benchmarks from the literature, further study is needed to refine characterization of As and Pb ecotoxicity in former orchard soils at the Hanford Site. Copyright © 2011 Wiley Periodicals, Inc.

Forage production of grass-legume binary mixtures on Intermountain Western USA irrigated pastures

USDA-ARS?s Scientific Manuscript database

A well-managed irrigated pasture is optimized for forage production with the use of N fertilizer which incurs extra expense. The objective was to determine which binary grass-legume mixture and mixture planting ratio of tall fescue (Festuca arundinacea Schreb.) (TF), meadow brome (Bromus bieberstei...

Genotype by environment interaction effects of propagation and defoliation on meadow bromegrass

USDA-ARS?s Scientific Manuscript database

Sixty-three meadow bromegrass (Bromus riparius Rehm.) half-sib families were evaluated over two years at Millville, UT location for biomass production and nutritive value. Families were evaluated under either space-plant or sward conditions combined with either grazed or cut management. The objectiv...

Notice of Release: 'Stress tolerant smooth bromegrass STSB'

USDA-ARS?s Scientific Manuscript database

The Agricultural Research Service, U.S. Department of Agriculture announces the release of a stress tolerant smooth bromegrass (STSB) [Bromus inermys, Leyss.] germplasm (PI xxxx) developed by Dr. Bryan K. Kindiger at the USDA-ARS Grazinglands Research Laboratory, El Reno, OK 73036. STSB is release...

Nitrous oxide emissions and herbage accumulation in smooth bromegrass pastures with nitrogen fertilizer and ruminant urine application

USDA-ARS?s Scientific Manuscript database

Agricultural soils contribute significantly to nitrous oxide (N2O) emissions, but little data is available on N2O emissions from smooth bromegrass (Bromus inermis Leyss.) pastures. This study evaluated soil N2O emissions and herbage accumulation from smooth bromegrass pasture in eastern Nebraska, US...

Searching for microbial biological control candidates for invasive grasses: coupling expanded field research with strides in biotechnology and grassland restoration

USDA-ARS?s Scientific Manuscript database

Highly invasive grasses (e.g. Bromus spp., Pennisetum ciliare, Taeniatherum caput-medusae) are largely unabated in much of the arid Western U.S., despite more than 70 years of control attempts with a wide array of tools and management practices. The development and sustained integration of new appro...

Host status of barley to Puccinia coronata from couch grass and P. striiformis from wheat and brome

USDA-ARS?s Scientific Manuscript database

The pathogenicity and identity of a field sample (PcE) of crown rust fungus Puccinia coronata collected in Hungary on wild couch grass (Elytrigia repens) and of a field sample (Psb) of stripe rust (P. striiformis) collected in the Netherlands on California brome (Bromus carinatus) was studied. We fo...

U.S. Air Forces Aerial Spray Mission: Should the Department of Defense Continue to Operate this Weapon of Mass Dispersion

DTIC Science & Technology

2015-12-01

pesticide application over farm fields to produce a better crop.2 On 3 August 1921 in a joint effort between the U.S. Army Signal Corps in Dayton, Ohio... pesticide dissemination because of the relatively small amount of product needed to spray for nuisance insects over a vast area. The ULV system is... pesticide per minute. Applications that require massive amounts of liquid herbicide to neutralize cheatgrass and other fire-prone, invasive vegetation on

Soil sulfur amendments suppress Selenium uptake by alfalfa and western wheatgrass

Treesearch

C. L. Mackowiak; M. C. Amacher

2008-01-01

Selenium (Se) is a potential soil contaminant in many parts of the world where it can pose a health risk to livestock and wildlife. Phosphate ore mining in Southeast Idaho has resulted in numerous waste rock dumps revegetated with forages to stabilize the dumps and support grazing. Alfalfa (Medicago sativa L.), smooth brome (Bromus inermis...

Registration of 'Newell' Smooth Bromegrass

USDA-ARS?s Scientific Manuscript database

‘Newell’ (Reg. No. CV-xxxx, PI 671851) smooth bromegrass (Bromus inermis Leyss.) is a steppe or southern type cultivar that is primarily adapted in the USA to areas north of 40o N lat. and east of 100o W long. that have 500 mm or more annual precipitation or in areas that have similar climate cond...

Planning Level Delineation and Geospatial Characterization of Aquatic Resources for San Jacinto and Portions of Santa Margarita Watersheds, Riverside County, California

DTIC Science & Technology

2003-03-01

Native__Salix lasiolepis 334 Bromus spp., Lactuca serriola Melilotus indica, Polypogon monspeliensis, Vitis californica, Xanthium strumarium , Populus...Veronica anagallis VERANA Lepidospartum squamatum LEPSQU Vitis californica VITCAL Limonium californicum LIMCAL Xanthium strumarium XANSTR Table 7...cracca Salix exigua Vulpia myuros Salix gooddingii Xanthium strumarium Salsola kali 72 ERDC/CRREL TR-03-4 APPENDIX H: VEGETATION MAP UNITS

Relocation of the 146th Tactical Airlift Wing of the California Air National Guard

DTIC Science & Technology

1985-02-01

Ephedra nevadensis C 0 A Nevada Morman Tea DICOTYLEDONES Asteraceae - Sunflower Family Acamptopappus sphaerocephalus 1 0 Goldenhead Ambrosia dumosa...blotched lizard (observed) Gopherus azassizi Desert tortoise Crotalus viridis Western rattlesnake Crotalus cerastes Sidewinder Tantilla planiceps Black...is Joshua Tree Woodland with Mormon Tea ( Ephedra sp.?), Cholla (Opuntia sp.?), Creosote-bush (Larrea Divaricata), Red Brome (Bromus rubens), Desert

Reproductive allocation strategies in desert and Mediterranean populations of annual plants grown with and without water stress.

PubMed

Aronson, J; Kigel, J; Shmida, A

1993-03-01

Reproductive effort (relative allocation of biomass to diaspore production) was compared in matched pairs of Mediterranean and desert populations of three unrelated annual species, Erucaria hispanica (L.) Druce, Bromus fasciculatus C. Presl. and Brachypodium distachyon (L.) Beauv., grown under high and low levels of water availability in a common-environment experiment. Desert populations in all three species showed higher reproductive effort than corresponding Mediterranean populations, as expressed by both a reproductive index (RI= reproductive biomass/vegetative biomass), and a reproductive efficiency index (REI=number of diaspores/total plant biomass). Moreover, in E. hispanica and Brachypodium distachyon, inter-populational differences in reproductive effort were greater under water stress, the main limiting factor for plant growth in the desert. These results indicate that variability in reproductive effort in response to drought is a critical and dynamic component of life history strategies in annual species in heterogeneous, unpredictable xeric environments. When subjected to water stress the Mediterranean populations of E. hispanica and B. distachyon showed greater plasticity (e.g. had a greater reduction) in reproductive effort than the desert populations, while in Bromus fasciculatus both populations showed similar amounts of plasticity.

Relocation of the 146th Tactical Airlift Wing of the California Air National Guard. Volume 2. Appendices

DTIC Science & Technology

1985-08-01

Status *Non-native species Y A L D GNETAE Ephedraceae - Joint Fir Family Ephedra nevadensis C 0 A Nevada Morman Tea DICOTYLEDONES 3 Asteraceae...tortoise Crotalus viridis Western rattlesnake Crotalus cerastes Sidewinder Tantilla planiceps Black-headed snake Bufo boreas Common toad Xantusia viiilis...plant community is Joshua Tree Woodland with Mormon STea ( Ephedra sp.?), Cholla (Opuntia sp.?), Creosote-bush (Larrea Divaricata), Red Brome (Bromus

Plant Succession at the Edges of Two Abandoned Cultivated Fields on the Arid Lands Ecology Reserve

DOE Office of Scientific and Technical Information (OSTI.GOV)

Simmons, Sally A.; Rickard, William H.

How vegetation recovers from disturbances is an important question for land managers. We examined 500 m2 plots to determine the progress made by native herbaceous plant species in colonizing the edges of abandoned cultivated fields at different elevations and microclimates, but with similar soils in a big sagebrush/bluebunch wheatgrass steppe. Alien species, especially cheatgrass and cereal rye, were the major competitors to the natives. The native species with best potential for restoring steppe habitats were sulphur lupine, hawksbeard, bottlebrush squirreltail, needle-and-thread grass, Sandberg's bluegrass, and several lomatiums.

Dated tribe-wide whole chloroplast genome phylogeny indicates recurrent hybridizations within Triticeae.

PubMed

Bernhardt, Nadine; Brassac, Jonathan; Kilian, Benjamin; Blattner, Frank R

2017-06-16

Triticeae, the tribe of wheat grasses, harbours the cereals barley, rye and wheat and their wild relatives. Although economically important, relationships within the tribe are still not understood. We analysed the phylogeny of chloroplast lineages among nearly all monogenomic Triticeae taxa and polyploid wheat species aiming at a deeper understanding of the tribe's evolution. We used on- and off-target reads of a target-enrichment experiment followed by Illumina sequencing. The read data was used to assemble the plastid locus ndhF for 194 individuals and the whole chloroplast genome for 183 individuals, representing 53 Triticeae species and 15 genera. We conducted Bayesian and multispecies coalescent analyses to infer relationships and estimate divergence times of the taxa. We present the most comprehensive dated Triticeae chloroplast phylogeny and review previous hypotheses in the framework of our results. Monophyly of Triticeae chloroplasts could not be confirmed, as either Bromus or Psathyrostachys captured a chloroplast from a lineage closely related to a Bromus-Triticeae ancestor. The most recent common ancestor of Triticeae occurred approximately between ten and 19 million years ago. The comparison of the chloroplast phylogeny with available nuclear data in several cases revealed incongruences indicating past hybridizations. Recent events of chloroplast capture were detected as individuals grouped apart from con-specific accessions in otherwise monopyhletic groups.

Greater sage-grouse as an umbrella species for sagebrush-associated vertebrates

USGS Publications Warehouse

Rowland, M.M.; Wisdom, M.J.; Suring, L.H.; Meinke, C.W.

2006-01-01

Widespread degradation of the sagebrush ecosystem in the western United States, including the invasion of cheatgrass, has prompted resource managers to consider a variety of approaches to restore and conserve habitats for sagebrush-associated species. One such approach involves the use of greater sage-grouse, a species of prominent conservation interest, as an umbrella species. This shortcut approach assumes that managing habitats to conserve sage-grouse will simultaneously benefit other species of conservation concern. The efficacy of using sage-grouse as an umbrella species for conservation management, however, has not been fully evaluated. We tested that concept by comparing: (1) commonality in land-cover associations, and (2) spatial overlap in habitats between sage-grouse and 39 other sagebrush-associated vertebrate species of conservation concern in the Great Basin ecoregion. Overlap in species' land-cover associations with those of sage-grouse, based on the ?? (phi) correlation coefficient, was substantially greater for sagebrush obligates (x??=0.40) than non-obligates (x??=0.21). Spatial overlap between habitats of target species and those associated with sage-grouse was low (mean ?? = 0.23), but somewhat greater for habitats at high risk of displacement by cheatgrass (mean ?? = 0.33). Based on our criteria, management of sage-grouse habitats likely would offer relatively high conservation coverage for sagebrush obligates such as pygmy rabbit (mean ?? = 0.84), but far less for other species we addressed, such as lark sparrow (mean ?? = 0.09), largely due to lack of commonality in land-cover affinity and geographic ranges of these species and sage-grouse.

Natural vegetation at the proposed Reference Repository Location in southeastern Washington

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rickard, W.H.

1988-02-01

The dominant shrubs were sagebrush and spiny hopsage; the herbs were dominated by cheatgrass and Sandberg bluegrass. Spiny hopsage appeared to be vulnerable to burning and also to damage by off-road vehicular traffic. It appears to have little or no ability to reproduce through seedlings; once the existing plants are killed they are not likely to be replaced, even if seed-producing plants are nearby. The only pure stand of spiny hopsage known to exist on the Hanford Site is on and near study plot 2H. Sagebrush, like spiny hopsage, is killed by burning and by heavy vehicles. Sagebrush is capablemore » of reproducing via seeds, indicating that it is an inherently aggressive species with a capacity to reestablish itself if parent plants are in the vicinity to act as seed sources. Alien, annual plants, especially cheatgrass, were a major contributor to the herbaceous canopy cover in plots 3S, 4S, and 5S. However, native perennial grasses, especially Sandberg bluegrass, were a major contributor to the canopy cover in plots 1S and 2H. These differences are probably caused by differences in soil properties (e.g., water retention capacity), rather than to historical disturbances such as livestock grazing or wildfire. Specimens of Sandwort, Arenaria franklinii, growing near the Reference Repository Location were collected for examination by taxonomists to determine if the specimens are of the variety A. f. thompsonii, a taxon currently listed as threatened in the state of Washington. 16 refs., 7 figs., 3 tabs.« less

Environmental Assessment of the 445th Airlift Wing Conversion from C-141C to C-5 Aircraft at Wright-Patterson Air Force Base, OH

DTIC Science & Technology

2004-08-01

communities include grasses such as bromegrass (Bromus spp.), goldenrod (Solidago spp.), ironweed ( Vernonia spp.), and some woody species. Associated old...virginicus NL T Tall larkspur a Delphinium exaltatum NL P Butternut b Juglans cinerea NL P Green Plains ladies’- tresses a, b Myriophyllum...verticillatum NL P False gromwell a Onosmodium molle NL P Royal catchfly a Silene regia NL P Pigeon Grape b Vitis cinerea NL P Sources: aWPAFB 2001a

The impact of invasive grasses on the population growth of Anemone patens, a long-lived native forb.

PubMed

Williams, Jennifer L; Crone, Elizabeth E

2006-12-01

Negative impacts of invasive plants on natives have been well documented, but much less is known about whether invasive plants can cause population level declines. We used demographic models to investigate the effects of two invasive grasses on the demography and population growth of Anemone patens, a long-lived native perennial of North American grasslands. Demographic data of A. patens growing in patches characterized by Bromus inermis, Poa pratensis, or native grasses were used to parameterize integral projection models. Models based on both average conditions and those allowing for environmental stochasticity indicate that A. patens is slowly increasing in patches of native grass (lambda = 1.02) and declining in patches of invasive grasses, particularly those dominated by B. inermis (lambda = 0.93). Extinction probabilities indicate that A. patens should persist in native grass patches, but has a much higher probability of extinction in Bromus patches compared to Poa patches. While sensitivity analyses showed that survival had the biggest effect on population growth rates in all habitats, results of a Life Table Response Experiment (LTRE) revealed that slower individual growth rates in patches of invasive grasses contributed the most to the observed reduction in population growth. These results suggest that invasive grasses may cause slow declines in A. patens, despite short-term coexistence, and that controlling B. inermis only would not be sufficient to ensure A. patens persistence.

Adaptive restoration of river terrace vegetation through iterative experiments

USGS Publications Warehouse

Dela Cruz, Michelle P.; Beauchamp, Vanessa B.; Shafroth, Patrick B.; Decker, Cheryl E.; O’Neil, Aviva

2014-01-01

Restoration projects can involve a high degree of uncertainty and risk, which can ultimately result in failure. An adaptive restoration approach can reduce uncertainty through controlled, replicated experiments designed to test specific hypotheses and alternative management approaches. Key components of adaptive restoration include willingness of project managers to accept the risk inherent in experimentation, interest of researchers, availability of funding for experimentation and monitoring, and ability to restore sites as iterative experiments where results from early efforts can inform the design of later phases. This paper highlights an ongoing adaptive restoration project at Zion National Park (ZNP), aimed at reducing the cover of exotic annual Bromus on riparian terraces, and revegetating these areas with native plant species. Rather than using a trial-and-error approach, ZNP staff partnered with academic, government, and private-sector collaborators to conduct small-scale experiments to explicitly address uncertainties concerning biomass removal of annual bromes, herbicide application rates and timing, and effective seeding methods for native species. Adaptive restoration has succeeded at ZNP because managers accept the risk inherent in experimentation and ZNP personnel are committed to continue these projects over a several-year period. Techniques that result in exotic annual Bromus removal and restoration of native plant species at ZNP can be used as a starting point for adaptive restoration projects elsewhere in the region.

Bird associations with shrubsteppe plant communities at the proposed reference repository location in southeastern Washington

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schuler, C.A.; Rickard, W.H.; Sargeant, G.A.

1988-03-01

This report provides information on te seasonal use of shrubsteppe vegetation by bird species at the RRL. Bird abundance and distribution were studied at the RRL to ensure that the DOE monitored migratory bird species pursuant to the Migratory Bird Treaty Act and to assess potential impacts of site characterization activities on bird populations. Birds were counted on two transects that together sampled an areas of 1.39 km/sup 2/. The relative abundance of birds, species richness, seasonal distribution, and the association of breeding shrubsteppe birds with major vegetation types were determined from Janurary through December 1987. Only 38 species weremore » counted during 82 surveys. Total bird density during the nesting season (March-June) was 42.96 birdskm/sup 2/ and the density for the entire year was 26.74 birdskm/sup 2/. The characteristic nesting birds in shrubsteppe habitats were western meadowlark, sage sparrow, burrowing owl, mourning dove, horned lark, long-billed curlew, lark sparrow, and loggerhead shrike. Western meadowlark and sage sparrows were the most abundant breeding birds with an average density of 11.25 and 7.76 birdskm/sup 2/, respectively. Seasonal distribution of birds varied with species, but most species were present from March to September. Distribution and abunandance of nesting birds were correlated with habitat type. About 63% of the habitat surveyed was sagebrush, 26% was cheatgrass, and 11% was spiny hopsage. Sagebrush habitat supproted a greeater total bird density than cheatgrass or hopsage habitats. Sage sparrows were closely associated with sagebrush habitats, while western meadowlarks showed no strong habitat affinities. 22 refs., 9 figs., 6 tabs« less

Cheatgrass facilitates spillover of a seed bank pathogen onto native grass species

Treesearch

Julie Beckstead; Susan E. Meyer; Brian M. Connolly; Michael B. Huck; Laura E. Street

2010-01-01

Attack by pathogens can have ecological consequences for plants at many scales, such as the individual, population and community scale, although the latter is the least studied. Community-level consequences of disease in natural plant communities can drive facilitation in succession (Van der Putten, Van Dijk & Peters 1993), maintain species diversity in...

Refining the cheatgrass–fire cycle in the Great Basin: Precipitation timing and fine fuel composition predict wildfire trends

USGS Publications Warehouse

Pilliod, David S.; Welty, Justin; Arkle, Robert

2017-01-01

Larger, more frequent wildfires in arid and semi-arid ecosystems have been associated with invasion by non-native annual grasses, yet a complete understanding of fine fuel development and subsequent wildfire trends is lacking. We investigated the complex relationships among weather, fine fuels, and fire in the Great Basin, USA. We first modeled the annual and time-lagged effects of precipitation and temperature on herbaceous vegetation cover and litter accumulation over a 26-year period in the northern Great Basin. We then modeled how these fine fuels and weather patterns influence subsequent wildfires. We found that cheatgrass cover increased in years with higher precipitation and especially when one of the previous 3 years also was particularly wet. Cover of non-native forbs and native herbs also increased in wet years, but only after several dry years. The area burned by wildfire in a given year was mostly associated with native herb and non-native forb cover, whereas cheatgrass mainly influenced area burned in the form of litter derived from previous years’ growth. Consequently, multiyear weather patterns, including precipitation in the previous 1–3 years, was a strong predictor of wildfire in a given year because of the time needed to develop these fine fuel loads. The strong relationship between precipitation and wildfire allowed us to expand our inference to 10,162 wildfires across the entire Great Basin over a 35-year period from 1980 to 2014. Our results suggest that the region's precipitation pattern of consecutive wet years followed by consecutive dry years results in a cycle of fuel accumulation followed by weather conditions that increase the probability of wildfire events in the year when the cycle transitions from wet to dry. These patterns varied regionally but were strong enough to allow us to model annual wildfire risk across the Great Basin based on precipitation alone.

Biological Survey Along the St. Lawrence River for the St. Lawrence Seaway. Additional Locks and other Navigation Improvements Study.

DTIC Science & Technology

1979-01-01

shiner K X K x No trps- FeathT6i des Emerald shiner K K K K K K NotroDP-s bifrenatus Bridle shiner K K K K K NiitoTi’ Tcornutus Commnon shiner K K K K K...Phleum pratense, Dactylis glomerata, Bromus inermis) (Geis, Hyduke, Gilman, Ruta , and Faust 1976) are dominant in the agricultural * llands and...P. Ruta and M.E. Faust. 1976. Plant communities along the St. Lawrence River Shoreline in New York State. SUNY College of Envir. Scl. and Forestry

Integrated Control and Assessment of Knapweed and Cheatgrass on Department of Defense Installations

DTIC Science & Technology

2005-01-01

SEFa/Olpidium chytrids at CO spotted knapweed (Centaurea maculosa Lam.) infested site managed by varied combinations of sucrose amendment, seeding and...hyphal lengths, and percent active hyphae, at CO Spotted Knapweed (Centaurea maculosa Lam.) infested site managed by varied combinations of sucrose...exotic and desirable (native non-invasive) plant species in CO plots infested with spotted knapweed (Centaurea maculosa Lam.) after three years of

Smooth brome (Bromus inermis Leyss) response to concrete grinding residue application

USDA-ARS?s Scientific Manuscript database

Concrete grinding residue (CGR) is a slurry byproduct created by concrete pavement maintenance operations. The application of CGR to roadside soils is not consistently regulated by state agencies across the United States. Much of this variability in regulation may be due to the lack of science-base...

AmeriFlux US-KFS Kansas Field Station

DOE Data Explorer

Brunsell, Nathaniel [Kansas University

2016-01-01

This is the AmeriFlux version of the carbon flux data for the site US-KFS Kansas Field Station. Site Description - The study is an abandoned grassland at the Kansas Field Station and Ecological Reserves. The site is located within the tallgrass prairie-deciduous forest ecotonal area. The site was subjected to intensive agriculture from the 1940s through the late 1960s. In the mid-1970s, the site was planted with the cool-season grass Bromus inermis and used as a hay meadow until 1987. Then, mowing and burning approximately every five years maintained it as a grassland until 2007, when the eddy flux tower was installed.

Integrated Control and Assessment of Knapweed and Cheatgrass on Department of Defense Installations. Addendum

DTIC Science & Technology

2008-02-01

United States are infested by exotic plant species, particularly knapweeds (Centaurea maculosa , C. diffusa) (Roché 1994, Hirsch and Leitch 1996, Sheley et...population of spotted knapweed (Centaurea maculosa ) at this site was identified by base personnel as a high priority for control. The area is regularly...2006. Comparative fungal responses in managed spotted knapweed (Centaurea maculosa Lam.), and diffuse knapweed (C. diffusa Lam.) - infested plant

Bromus response to climate and projected changes with climate change [Chapter 9

Treesearch

Bethany A. Bradley; Caroline A. Curtis; Jeanne C. Chambers

2016-01-01

A prominent goal of invasive plant management is to prevent or reduce the spread of invasive species into uninvaded landscapes and regions. Monitoring and control efforts often rely on scientific knowledge of suitable habitat for the invasive species. However, rising temperatures and altered precipitation projected with climate change are likely to shift the...

Gene capture from across the grass family in the allohexaploid Elymus repens (L.) Gould (Poaceae, Triticeae) as evidenced by ITS, GBSSI, and molecular cytogenetics.

PubMed

Mahelka, Václav; Kopecký, David

2010-06-01

Four accessions of hexaploid Elymus repens from its native Central European distribution area were analyzed using sequencing of multicopy (internal transcribed spacer, ITS) and single-copy (granule-bound starch synthase I, GBSSI) DNA in concert with genomic and fluorescent in situ hybridization (GISH and FISH) to disentangle its allopolyploid origin. Despite extensive ITS homogenization, nrDNA in E. repens allowed us to identify at least four distinct lineages. Apart from Pseudoroegneria and Hordeum, representing the major genome constituents, the presence of further unexpected alien genetic material, originating from species outside the Triticeae and close to Panicum (Paniceae) and Bromus (Bromeae), was revealed. GBSSI sequences provided information complementary to the ITS. Apart from Pseudoroegneria and Hordeum, two additional gene variants from within the Triticeae were discovered: One was Taeniatherum-like, but the other did not have a close relationship with any of the diploids sampled. GISH results were largely congruent with the sequence-based markers. GISH clearly confirmed Pseudoroegneria and Hordeum as major genome constituents and further showed the presence of a small chromosome segment corresponding to Panicum. It resided in the Hordeum subgenome and probably represents an old acquisition of a Hordeum progenitor. Spotty hybridization signals across all chromosomes after GISH with Taeniatherum and Bromus probes suggested that gene acquisition from these species is more likely due to common ancestry of the grasses or early introgression than to recent hybridization or allopolyploid origin of E. repens. Physical mapping of rDNA loci using FISH revealed that all rDNA loci except one minor were located on Pseudoroegneria-derived chromosomes, which suggests the loss of all Hordeum-derived loci but one. Because homogenization mechanisms seem to operate effectively among Pseudoroegneria-like copies in this species, incomplete ITS homogenization in our samples

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kremer, R.G.

Three papers are presented that focus on remote sensing and ecosystem simulation modeling of the Intermountain Northwest sagebrush-steppe ecosystem. The first utilizes Advanced Very High Resolution Radiometer data to derive seasonal greenness indices of three pre-dominant vegetation communities in south-central WashingtoN. Temporal signatures were statistically separated, and used to create a classification for the three communities by integrating Normalized Difference Vegetation Indices over the growing season. The classification accuracy was 75% when compared to 53 ground-truthed sites, but was less accurate (62%) in a more topographically variable region. The second paper develops a logic for treating the intermountain sagebrush-steepe asmore » a mosaic of distinct, hydrologically partitioned vegetation communities, and identifies critical ecophysiological considerations for process modeling of arid ecosystems. Soil water and nutrient dynamics of an ecosystem process model were modified to simulate productivity and seasonal water use patterns in Artemisia, Agropyron, and Bromus communities for the same study site. 60 year simulations maintained steady state vegetation productivity while predicting soil moisture content for 65 dates in 1992 with R[sup 2] values ranging from 0.93 to 0.98. In the third paper, the model was used to derive projections of the response of the ecosystem to natural and general circulation model (GCM)-predicted climate variability. Simulations predicted the adaptability of a less productive, invasive grass community (Bromus) to climate change, while a native sagebrush (Artemisia) community does not survive the increased temperatures of the GCM climates. High humidity deficits and greater maintenance respiration costs associated with increased temperatures limit the ability of the sagebrush community to support a relatively high biomass, and substantial increases in soil water storage and subsurface outflow occur was the vegetation

Exceptionally High Levels of Genetic Diversity in Wheat Curl Mite (Acari: Eriophyidae) Populations from Turkey.

PubMed

Szydło, W; Hein, G; Denizhan, E; Skoracka, A

2015-08-01

Recent research on the wheat curl mite species complex has revealed extensive genetic diversity that has distinguished several genetic lineages infesting bread wheat (Triticum aestivum L.) and other cereals worldwide. Turkey is the historical region of wheat and barley (Hordeum vulgare L.) domestication and diversification. The close relationship between these grasses and the wheat curl mite provoked the question of the genetic diversity of the wheat curl mite in this region. The scope of the study was to investigate genetic differentiation within the wheat curl mite species complex on grasses in Turkey. Twenty-one wheat curl mite populations from 16 grass species from nine genera (Agropyron sp., Aegilops sp., Bromus sp., Elymus sp., Eremopyrum sp., Hordeum sp., Poa sp., Secale sp., and Triticum sp.) were sampled in eastern and southeastern Turkey for genetic analyses. Two molecular markers were amplified: the cytochrome oxidase subunit I coding region of mtDNA (COI) and the D2 region of 28S rDNA. Phylogenetic analyses revealed high genetic variation of the wheat curl mite in Turkey, primarily on Bromus and Hordeum spp., and exceptionally high diversity of populations associated with bread wheat. Three wheat-infesting wheat curl mite lineages known to occur on other continents of the world, including North and South America, Australia and Europe, were found in Turkey, and at least two new genetic lineages were discovered. These regions of Turkey exhibit rich wheat curl mite diversity on native grass species. The possible implications for further studies on the wheat curl mite are discussed. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Emergence and growth of four winterfat accessions in the presence of the exotic annual cheatgrass

Treesearch

Ann L. Hild; Jennifer M. Muscha; Nancy L. Shaw

2007-01-01

Winterfat (Krascheninnikovia lanata [Pursh] A. D. J. Meeuse & Smit; synonym: Ceratoides lanata [Pursh] J. T. Howell) is a desired shrub species and an integral component of salt desert shrublands in the Intermountain West. On the Snake River Birds of Prey National Conservation Area in southwestern Idaho, extensive loss of...

Greater bud outgrowth of Bromus inermis than Pascopyrum smithii under multiple environmental conditions

Treesearch

Jacqueline P. Ott; Jack L. Butler; Yuping Rong; Lan. Xu

2017-01-01

Tiller recruitment of perennial grasses in mixed-grass prairie primarily occurs from belowground buds. Environmental conditions, such as temperature, soil moisture and grazing can affect bud outgrowth of both invasive and native perennial grasses. Differential bud outgrowth responses of native and invasive species to climate change and grazing could alter...

Supplement Analysis for the Transmission System Vegetation Management Program FEIS (DOE/EIS-0285-SA-32) - Re-Vegetation Plot Study Along the Lower Monumental-McNary Transmission Line ROW

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hutchinson, Ken

2001-11-15

Re-vegetation Plot Study along the Lower Monumental-McNary Transmission Line ROW. The study area sections are located near structures 38/4 and 39/3. The line is a 500kV Single Circuit Transmission Line having an easement width of 165 feet. The proposed work will be accomplished in the indicated sections of the transmission line corridor as indicated on the attached checklist. A summer of 2001 fire burned the subject area leaving the ROW in a bare ground situation. Before, the fire the site was dominated by annual vegetation (cheatgrass) and noxious weeds (yellowstar thistle). As a study of plant succession after the firemore » for a local Boy Scout group, two 100 X 100 foot areas will be identified for study over the next 2-3 years. The two test plots will be identified and permanently marked. One will receive treatment while the other will not be treated and used as a control plot.« less

Response of young ponderosa pines, shrubs, and grasses to two release treatments. Forest Service research note

DOE Office of Scientific and Technical Information (OSTI.GOV)

McDonald, P.M.; Everest, G.A.

1996-07-01

To release a young pine plantation on a medium site in central California, herbicides and mulches were applied soon after planting to study their effectiveness. Bearclover is an aggressive shrub species that resprouts from rhizomes after disturbance, and must be controlled if young conifer seedlings are to become established. After 4 years, resprouting bearclover plants numbered 282,000 per acre in the control, but less than 4,000 per acre in the plots treated by herbicides. Mean foliar cover was 63 percent versus 1 percent for control and herbicide plots, respectively. Ponderosa pine seedlings were significantly taller, had larger mean diameters, andmore » survived better in the herbicide treatment than counterparts in mulched plots and control. The 5-foot square mulches were ineffective for controlling bearclover. Cheatgrass invaded the plantation in the second year, and after 2 more years became abundant in herbicide plots and plentiful in the control.« less

White Sweetclover (Melilotus albus) and Narrowleaf Hawksbeard (Crepis tectorum) Seed Germination after Passing Through Moose

USDA-ARS?s Scientific Manuscript database

White sweetclover and narrowleaf hawksbeard are non-indigenous invasive plant species in Alaska that are rapidly spreading, including into areas that are otherwise free of non-indigenous plants. There has been concern that native moose could be dispersing viable seed from these plants after ingestio...

Enhancing Pre- and Post-Wildfire Vegetation Recovery and Understanding Feedbacks of Cheatgrass invasion Using NASA Earth Observations

NASA Astrophysics Data System (ADS)

Olsen, N.; Counts, A.; Quistorff, C.; Ohr, C. A.; Toner, C.

2017-12-01

Increasing wildfire frequency and severity has emphasized the importance of post-wildfire recovery efforts in southern Idaho's sagebrush ecosystems. These changing fire regimes favor invasive grass species while hindering native sagebrush habitat regeneration, causing a positive feedback cycle of invasive growth - wildfires - invasive growth. Due to this undesirable process and anthropogenic influences, the sagebrush ecosystem is one of the most endangered in the US. In this project the NASA DEVELOP group of Pocatello, Idaho partnered with the Bureau of Land Management, Idaho Department of Fish and Game, and the US Department of Agriculture to characterize ecosystem recovery following the Crystal (2006), Henry Creek (2016), Jefferson (2010), and Soda (2015) wildfires. Determining vegetation cover heterogeneity and density can be time consuming and the factors affecting ecosystem recovery can be complex. In addition, restoration success is difficult to determine as vegetation composition is not often known prior to wildfire events and monitoring vegetation composition after restoration efforts can be resource intensive. These wildfires temporal monitoring consisted of 2001 to 2017 using NASA Earth observations such as Landsat 5 Thermal Mapper (TM), Landsat 8 Operational Land Imager (OLI), Terra Moderate Resolution Imaging Spectroradiometer (MODIS), and Shuttle Radar Topography Mission (SRTM) to determine the most significant factors of wildfire recovery and the influence targeted grazing could have for recovery. In addition, this project will include monitoring of invasive species propagation and whether spatial patterns or extents of the wildfire contribute to propagation. Understanding the key variables that made reseeding and natural recovery work in some areas, assessing why they failed in others, and identifying factors that made non-native propagation ideal are important issues for land managers in this region.

Influence of plant invasion on seed chemistry of winterfat, green rabbitbrush, freckled milkvetch, indian ricegrass and cheatgrass

USDA-ARS?s Scientific Manuscript database

Plant invasions have proven detrimental to numerous ecosystem processes; however, limited information exists on how plant invasions affect seed nutrients. We quantified nutrients in seeds of Indian ricegrass (Achnatherum hymenoides), green rabbitbrush (Chrysothamnus viscidiflorus), winterfat (Krasch...

Restoration of areas disturbed by site studies for a mined commercial radioactive waste repository: The Basalt Waste Isolation Project (BWIP)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brandt, C.A.; Rickard, W.H. Jr.; Biehert, R.W.

1989-01-01

The Basalt Waste Isolation Project (BWIP) was undertaken to environmentally characterize a portion of the US Department of Energy's Hanford Site in Washington State as a potential host for the nation's first mined commercial nuclear waste repository. Studies were terminated by Congress in 1987. Between 1976 and 1987, 72 areas located across the Hanford Site were disturbed by the BWIP. These areas include borehole pads, a large Exploratory Shaft Facility, and the Near Surface Test Facility. Most boreholes were cleared of vegetation, leveled, and stabilized with a thick layer of compacted pit-run gravel and sand. The Near Surface Test Facilitymore » consists of three mined adits, a rock-spoils bench, and numerous support facilities. Restoration began in 1988 with the objective of returning sites to pre-existing conditions using native species. The Hanford Site retains some of the last remnants of the shrub-steppe ecosystem in Washington. The primary constraints to restoring native vegetation at Hanford are low precipitation and the presence of cheatgrass, an extremely capable alien competitor. 5 figs.« less

River flow and riparian vegetation dynamics - implications for management of the Yampa River through Dinosaur National Monument

USGS Publications Warehouse

Scott, Michael L; Friedman, Jonathan M.

2018-01-01

This report addresses the relation between flow of the Yampa River and occurrence of herbaceous and woody riparian vegetation in Dinosaur National Monument (DINO) with the goal of informing management decisions related to potential future water development. The Yampa River in DINO flows through diverse valley settings, from the relatively broad restricted meanders of Deerlodge Park to narrower canyons, including debris fan-affected reaches in the upper Yampa Canyon and entrenched meanders in Harding Hole and Laddie Park. Analysis of occurrence of all plant species measured in 1470 quadrats by multiple authors over the last 24 years shows that riparian vegetation along the Yampa River is strongly related to valley setting and geomorphic surfaces, defined here as active channel, active floodplain, inactive floodplain, and upland. Principal Coordinates Ordination arrayed quadrats and species along gradients of overall cover and moisture availability, from upland and inactive floodplain quadrats and associated xeric species like western wheat grass (Pascopyrum smithii), cheatgrass (Bromus tectorum), and saltgrass (Distichlis spicata) to active channel and active floodplain quadrats supporting more mesic species including sandbar willow (Salix exigua), wild licorice (Glycyrrhiza lepidota), and cordgrass (Spartina spp.). Indicator species analysis identified plants strongly correlated with geomorphic surfaces. These species indicate state changes in geomorphic surfaces, such as the conversion of active channel to floodplain during channel narrowing. The dominant woody riparian species along the Yampa River are invasive tamarisk (Tamarix ramosissima), and native Fremont cottonwood (Populus deltoides ssp. wislizenii), box elder (Acer negundo L. var. interius), and sandbar willow (Salix exigua). These species differ in tolerance of drought, salinity, inundation, flood disturbance and shade, and in seed size, timing of seed dispersal and ability to form root sprouts. These

Negative impacts of invasive plants on conservation of sensitive desert wildlife

USGS Publications Warehouse

Drake, K. Kristina; Bowen, Lizabeth; Nussear, Kenneth E.; Esque, Todd C.; Berger, Andrew J.; Custer, Nathan; Waters, Shannon C.; Johnson, Jay D.; Miles, A. Keith; Lewison, Rebecca L.

2016-01-01

Habitat disturbance from development, resource extraction, off-road vehicle use, and energy development ranks highly among threats to desert systems worldwide. In the Mojave Desert, United States, these disturbances have promoted the establishment of nonnative plants, so that native grasses and forbs are now intermixed with, or have been replaced by invasive, nonnative Mediterranean grasses. This shift in plant composition has altered food availability for Mojave Desert tortoises (Gopherus agassizii), a federally listed species. We hypothesized that this change in forage would negatively influence the physiological ecology, immune competence, and health of neonatal and yearling tortoises. To test this, we monitored the effects of diet on growth, body condition, immunological responses (measured by gene transcription), and survival for 100 captive Mojave tortoises. Tortoises were assigned to one of five diets: native forbs, native grass, invasive grass, and native forbs combined with either the native or invasive grass. Tortoises eating native forbs had better body condition and immune functions, grew more, and had higher survival rates (>95%) than tortoises consuming any other diet. At the end of the experiment, 32% of individuals fed only native grass and 37% fed only invasive grass were found dead or removed from the experiment due to poor body conditions. In contrast, all tortoises fed either the native forb or combined native forb and native grass diets survived and were in good condition. Health and body condition quickly declined for tortoises fed only the native grass (Festuca octoflora) or invasive grass (Bromus rubens) with notable loss of fat and muscle mass and increased muscular atrophy. Bromus rubens seeds were found embedded in the oral mucosa and tongue in most individuals eating that diet, which led to mucosal inflammation. Genes indicative of physiological, immune, and metabolic functions were transcribed at lower levels for individuals fed B

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

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 allmore » 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.« less

Effects of livestock watering sites on alien and native plants in the Mojave Desert, USA

USGS Publications Warehouse

Brooks, M.L.; Matchett, J.R.; Berry, K.H.

2006-01-01

Increased livestock densities near artificial watering sites create disturbance gradients called piospheres. We studied responses of alien and native annual plants and native perennial plants within 9 piospheres in the Mojave Desert of North America. Absolute and proportional cover of alien annual plants increased with proximity to watering sites, whereas cover and species richness of native annual plants decreased. Not all alien species responded the same, as the alien forb Erodium cicutarium and the alien grass Schismus spp. increased with proximity to watering sites, and the alien annual grass Bromus madritensis ssp. rubens decreased. Perennial plant cover and species richness also declined with proximity to watering sites, as did the structural diversity of perennial plant cover classes. Significant effects were focused within 200 m of the watering sites, suggesting that control efforts for alien annual plants and restoration efforts for native plants should optimally be focused within this central part of the piosphere gradient.

Invasive plant species: Inventory, mapping, and monitoring - A national strategy

USGS Publications Warehouse

Ludke, J. Larry; D'Erchia, Frank; Coffelt, Jan; Hanson, Leanne

2002-01-01

America is under siege by invasive species of plants and animals, and by diseases. The current environmental, economic, and health-related costs of invasive species could exceed $138 billion per year-more than all other natural disasters combined. Notorious examples include West Nile virus, Dutch elm disease, chestnut blight, and purple loose- strife in the Northeast; kudzu, Brazilian peppertree, water hyacinth, nutria, and fire ants in the Southeast; zebra mussels, leafy spurge, and Asian long-horn beetles in the Midwest; salt cedar, Russian olive, and Africanized bees in the Southwest; yellow star thistle, European wild oats, oak wilt disease, Asian clams, and white pine blister rust in California; cheatgrass, various knapweeds, and thistles in the Great Basin; whirling disease of salmonids in the Northwest; hundreds of invasive species from microbes to mammals in Hawaii; and the brown tree snake in Guam. Thousands of species from other countries are introduced intentionally or accidentally into the United States each year. Based on past experience, 10-15 percent can be expected to establish free-living populations and about 1 percent can be expected to cause significant impacts to ecosystems, native species, economic productivity, and (or) human health.

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

Treesearch

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

2010-01-01

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...

Interference of condensed tannin in lignin analyses of dry bean and forage crops.

PubMed

Marles, M A Susan; Coulman, Bruce E; Bett, Kirstin E

2008-11-12

Legumes with high concentrations of condensed tannin (pinto bean [Phaseolus vulgaris L.], sainfoin [Onobrychis viciifolia Scop.], and big trefoil [Lotus uliginosus Hoff.]), were compared to a selection of forages, with low or zero condensed tannin (smooth bromegrass [ Bromus inermis Leyss], Lotus japonicus [Regel] K. Larsen, and alfalfa [Medicago sativa L.]), using four methods to estimate fiber or lignin. Protocols were validated by using semipurified condensed tannin polymers in adulteration assays that tested low-lignin tissue with polyphenolic-enriched samples. The effect on lignin assay methods by condensed tannin concentration was interpreted using a multivariate analysis. There was an overestimation of fiber or lignin in the presence of condensed tannin in the acid detergent fiber (ADF) and Klason lignin (KL) assays compared to that in the thioglycolic acid (TGA) and acid detergent lignin (ADL) methods. Sulfite reagents (present in TGA lignin method) or sequential acidic digests at high temperatures (ADF followed by ADL) were required to eliminate condensed tannin. The ADF (alone) and KL protocols are not recommended to screen nonwoody plants, such as forages, where condensed tannin has accumulated in the tissue.

Minimizing effects of methodological decisions on interpretation and prediction in species distribution studies: An example with background selection

USGS Publications Warehouse

Jarnevich, Catherine S.; Talbert, Marian; Morisette, Jeffrey T.; Aldridge, Cameron L.; Brown, Cynthia; Kumar, Sunil; Manier, Daniel; Talbert, Colin; Holcombe, Tracy R.

2017-01-01

Evaluating the conditions where a species can persist is an important question in ecology both to understand tolerances of organisms and to predict distributions across landscapes. Presence data combined with background or pseudo-absence locations are commonly used with species distribution modeling to develop these relationships. However, there is not a standard method to generate background or pseudo-absence locations, and method choice affects model outcomes. We evaluated combinations of both model algorithms (simple and complex generalized linear models, multivariate adaptive regression splines, Maxent, boosted regression trees, and random forest) and background methods (random, minimum convex polygon, and continuous and binary kernel density estimator (KDE)) to assess the sensitivity of model outcomes to choices made. We evaluated six questions related to model results, including five beyond the common comparison of model accuracy assessment metrics (biological interpretability of response curves, cross-validation robustness, independent data accuracy and robustness, and prediction consistency). For our case study with cheatgrass in the western US, random forest was least sensitive to background choice and the binary KDE method was least sensitive to model algorithm choice. While this outcome may not hold for other locations or species, the methods we used can be implemented to help determine appropriate methodologies for particular research questions.

Ecological effects of large fires on US landscapes: benefit or catastrophe?

USGS Publications Warehouse

Keane, Robert E.; Agee, James K.; Fule, Peter; Keeley, Jon E.; Key, Carl H.; Kitchen, Stanley G.; Miller, Richard; Schulte, Lisa A.

2008-01-01

The perception is that today’s large fires are an ecological catastrophe because they burn vast areas with high intensities and severities. However, little is known of the ecological impacts of large fires on both historical and contemporary landscapes. The present paper presents a review of the current knowledge of the effects of large fires in the United States by important ecosystems written by regional experts. The ecosystems are (1) ponderosa pine–Douglas-fir, (2) sagebrush–grasslands, (3) piñon–juniper, (4) chaparral, (5) mixed-conifer, and (6) spruce–fir. This review found that large fires were common on most historical western US landscapes and they will continue to be common today with exceptions. Sagebrush ecosystems are currently experiencing larger, more severe, and more frequent large fires compared to historical conditions due to exotic cheatgrass invasions. Historical large fires in south-west ponderosa pine forest created a mixed severity mosaic dominated by non-lethal surface fires while today’s large fires are mostly high severity crown fires. While large fires play an important role in landscape ecology for most regions, their importance is much less in the dry piñon–juniper forests and sagebrush–grasslands. Fire management must address the role of large fires in maintaining the health of many US fire-dominated ecosystems.

Holocene fire occurrence and alluvial responses at the leading edge of pinyon–juniper migration in the Northern Great Basin, USA

USGS Publications Warehouse

Weppner, Kerrie N.; Pierce, Jennifer L.; Betancourt, Julio L.

2013-01-01

Fire and vegetation records at the City of Rocks National Reserve (CIRO), south-central Idaho, display the interaction of changing climate, fire and vegetation along the migrating front of single-leaf pinyon (Pinus monophylla) and Utah juniper (Juniperus osteosperma). Radiocarbon dating of alluvial charcoal reconstructed local fire occurrence and geomorphic response, and fossil woodrat (Neotoma) middens revealed pinyon and juniper arrivals. Fire peaks occurred ~ 10,700–9500, 7200–6700, 2400–2000, 850–700, and 550–400 cal yr BP, whereas ~ 9500–7200, 6700–4700 and ~ 1500–1000 cal yr BP are fire-free. Wetter climates and denser vegetation fueled episodic fires and debris flows during the early and late Holocene, whereas drier climates and reduced vegetation caused frequent sheetflooding during the mid-Holocene. Increased fires during the wetter and more variable late Holocene suggest variable climate and adequate fuels augment fires at CIRO. Utah juniper and single-leaf pinyon colonized CIRO by 3800 and 2800 cal yr BP, respectively, though pinyon did not expand broadly until ~ 700 cal yr BP. Increased fire-related deposition coincided with regional droughts and pinyon infilling ~ 850–700 and 550–400 cal yr BP. Early and late Holocene vegetation change probably played a major role in accelerated fire activity, which may be sustained into the future due to pinyon–juniper densification and cheatgrass invasion.

Final Report for Emergency Stabilization and Rehabilitation Treatment Monitoring of the Keeney Pass, Cow Hollow, Double Mountain, and Farewell Bend Fires

USGS Publications Warehouse

Wirth, Troy A.; Pyke, David A.

2009-01-01

2006 and 0.09 plants/m2 in 2008. Density of seeded perennial grasses at the Double Mountain non-native and native seeding were 2.72 and 3.86 plants/m2 in 2006 and 0.90 and 1.74 plants/m2 in 2008, respectively. The Farewell Bend non-native seeding resulted in 5.62 plants/m2 in 2006 and 0.42 plants/m2 in 2008 while the native seeding had 2.22 seeded grass plants/m2 in 2006 and 0.44 plants/m2 by 2008. The primary reason for low level of establishment on most treatments except the Cow Hollow seeding was most likely the unfavorable timing and amount of precipitation in 2007 and 2008. Measurements of density within the first 3 years provide the best estimate of initial seeding success. Increases in cover due to the seedings were not detectable in the first 3 years following seeding in this monitoring effort. Changes in cover resulting from the treatments may be detectable in cases where the seedings were very successful in the first 3 years following seeding, but in areas with lower annual average precipitation, may not occur consistently. As a result, cover of seeded species may not be a good indication of seeding success in the early years after treatment. However, cover is useful for monitoring initial patterns of abundance of naturally recovering vegetation, exotic annual grasses and forbs, and bare ground. Cover measurements at these four sites revealed patterns common to most of the treatment areas in cover of litter, bare ground, and exotic annuals in response to drill seeding and weather patterns. There was a rapid increase in litter at all treatments after the fire. Additionally, there was less litter in treatment plots than in the control plots in 2006 probably due to the mechanical action of the seed drill. There also was a corresponding decrease in bare ground from 2006 to 2008. Initially, higher bare ground cover at treatment plots appears to be due to the mechanical action of the seed drill. Cover of annual grasses, primarily Bromus tectorum,

Monitoring Soil Erosion on a Burned Site in the Mojave-Great Basin Transition Zone: Final Report for the Jacob Fire Site

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miller, Julianne; Etyemezian, Vic; Cablk, Mary E.

throughout the study period. Seldom, if ever, did runoff and sediment occur in burned drainage area soils. For burned soils where runoff occurred at 1 MAB, the sediment size was finer than on unburned sites, but this effect disappeared by 3 MAB. For the three year study under the conditions tested at the Jacob Fire site, the potential for water erosion appeared relatively unaffected by the fire. Vegetation responses were documented for each year following the fire. By the end of the study, there was a substantial difference in plant densities and richness between drainage and ridge sites. Cheatgrass densities were higher in unburned plots, and cheatgrass was also more dominant in the community composition in unburned plots. Cheatgrass had increased in the burned area but so did other native species. Three years after the fire, the burned landscape continued to revegetate but had yet to approximate the condition of an unburned landscape. The results from the vegetation surveys support the wind erosion results, where the primary source of windborne particles originate from the understory, where lower plant diversity and densities were found. The soil appears to be more resilient and have a much shorter recovery time than the vegetation in this particular community.« less

Brome mosaic virus, good for an RNA virologist's basic needs.

PubMed

Kao, C C; Sivakumaran, K

2000-03-01

Abstract Taxonomic relationship: Type member of the Bromovirus genus, family Bromoviridae. A member of the alphavirus-like supergroup of positive-sense single-stranded RNA viruses. Physical properties: Virions are nonenveloped icosahedrals made up of 180 coat protein subunits (Fig. 1). The particles are 26 nm in diameter and contain 22% nucleic acid and 78% protein. The BMV genome is composed of three positive-sense, capped RNAs: RNA1 (3.2 kb), RNA2 (2.9 kb), RNA3 (2.1 kb) (Fig. 2). Viral proteins: RNA1 encodes protein 1a, containing capping and putative RNA helicase activities. RNA2 encodes protein 2a, a putative RNA-dependent RNA polymerase. RNA3 codes for two proteins: 3a, which is required for cell-to-cell movement, and the capsid protein. The capsid is translated from a subgenomic RNA, RNA4 (1.2 kb). Hosts: Monocots in the Poacea family, including Bromus inermis, Zea mays and Hordeum vulgare, in which BMV causes brown streaks. BMV can also infect the dicots Nicotiana benthamiana and several Chenopodium species. In N. benthamiana, the infection is asymptomatic while infection of Chenopodium can cause either necrotic or chlorotic lesions. Useful website:http://www4.ncbi.nlm.nih.gov/ICTVdb/ICTVdB/10030001.htm.

Common mycelial networks impact competition in an invasive grass.

PubMed

Workman, Rachael E; Cruzan, Mitchell B

2016-06-01

Mycorrhizal hyphal complexes can connect multiple host plants to form common mycelial networks (CMNs) that may affect plant competitive outcomes and community composition through differential resource allocation. The impacts of CMN interactions on invasive plants are not well understood and could be crucial to the understanding of invasive plant establishment and success. We grew the invasive grass Brachypodium sylvaticum in intra- and interspecific pairings with native grass Bromus vulgaris in a greenhouse and controlled for the effects of CMN and root interactions by manipulating the belowground separation between competitors. Comparison of plant growth in pots that allowed CMN interactions and excluded root competition and vice versa, or both, allowed us to delineate the effects of network formation and root competition on invasive plant establishment and performance. Brachypodium sylvaticum grown in pots allowing for only hyphal interactions, but no root competition, displayed superior growth compared with conspecifics in other treatments. Invasive performance was poorest when pairs were not separated by a barrier. Shoot nitrogen content in B. sylvaticum was higher in mycorrhizal plants only when connections were allowed between competitors. Our results indicate that the presence of CMN networks can have positive effects on B. sylvaticum establishment and nutrient status, which may affect plant competition and invasion success. © 2016 Botanical Society of America.

Effects of high fire frequency in creosote bush scrub vegetation of the Mojave Desert

USGS Publications Warehouse

Brooks, M.L.

2012-01-01

Plant invasions can increase fire frequency in desert ecosystems where fires were historically infrequent. Although there are many resource management concerns associated with high frequency fire in deserts, fundamental effects on plant community characteristics remain largely unstudied. Here I describe the effects of fire frequency on creosote bush scrub vegetation in the Mojave Desert, USA. Biomass of the invasive annual grass Bromus rubens L. increased following fire, but did not increase further with additional fires. In contrast, density, cover and species richness of native perennial plants each decreased following fire and continued to decrease with subsequent fires, although not as dramatically as after the initial fire. Responses were similar 5 and 14 years post-fire, except that cover of Hymenoclea salsola Torr. & A. Gray and Achnatherum speciosa Trin. & Rupr. both increased in areas burnt once. These results suggest that control of B. rubens may be equally warranted after one, two or three fires, but revegetation of native perennial plants is most warranted following multiple fires. These results are valid within the scope of this study, which is defined as relatively short term vegetation responses (???14 years) to short fire return intervals (6.3 and 7.3 years for the two and three fire frequency levels) within creosote bush scrub of the Mojave Desert. ?? 2012 IAWF.

Vascular flora of saline lakes in the southern high plains of Texas and eastern New Mexico

USGS Publications Warehouse

Rosen, David J.; Conway, Warren C.; Haukos, David A.; Caskey, Amber D.

2013-01-01

Saline lakes and freshwater playas form the principal surface hydrological feature of the High Plains of the Southern Great Plains. Saline lakes number less than 50 and historically functioned as discharge wetlands with relatively consistent water availability due to the presence of one or more springs. Currently, less than ten saline lakes contain functional springs. A survey of vascular plants at six saline lakes in the Southern High Plains of northwest Texas and one in eastern New Mexico during May and September 2009 resulted in a checklist of 49 species representing 16 families and 40 genera. The four families with the most species were Asteraceae (12), Amaranthaceae (8), Cyperaceae (5), and Poaceae (12). Non-native species (Bromus catharticus, Poa compressa, Polypogon monspeliensis, Sonchus oleraceus, Kochia scoparia, and Tamarix ramosissima) accounted for 10% of the total species recorded. Whereas nearly 350 species of vascular plants have been identified in playas in the Southern High Plains, saline lakes contain a fraction of this species richness. The Southern High Plains saline lake flora is regionally unique, containing taxa not found in playas, with species composition that is more similar to temperate desert wetlands of the Intermountain Region and Gulf Coastal Plain of North America.

Identification of brome grass infestations in southwest Oklahoma using multi-temporal Landsat imagery

NASA Astrophysics Data System (ADS)

Yan, D.; de Beurs, K.

2013-12-01

The extensive infestation of brome grasses (Cheatgrass, Rye brome and Japanese brome) in southwest Oklahoma imposes negative impacts on local economy and ecosystem in terms of decreasing crop and forage production and increasing fire risk. Previously proposed methodologies on brome grass detection are found ill-suitable for southwest Oklahoma as a result of similar responses of background vegetation to inter-annual variability of rainfall. In this study, we aim to identify brome grass infestations by detecting senescent brome grasses using the 2011 Cultivated Land Cover Data Sets and the difference Normalized Difference Infrared Index (NDII) derived from multi-temporal Landsat imagery. Landsat imageries acquired on May 18th and June 10th 2013 by Operational Land Imager and Enhanced Thematic Mapper plus were used. The imagery acquisition dates correspond to the peak growth and senescent time of brome grasses, respectively. The difference NDII was calculated by subtracting the NDII image acquired in May from the June NDII image. Our hypotheses is that senescent brome grasses and crop/pasture fields harvested between the two image acquisition dates can be distinguished from background land cover classes because of their increases in NDII due to decreased water absorption by senescent vegetation in the shortwave infrared region. The Cultivated Land Cover Data Sets were used to further separate senescent brome grass patches from newly harvested crop/pasture fields. Ground truth data collected during field trips in June, July and August of 2013 were used to validate the detection results.

Eder Acquisition 2007 Habitat Evaluation Procedures Report.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ashley, Paul R.

A habitat evaluation procedures (HEP) analysis was conducted on the Eder acquisition in July 2007 to determine how many protection habitat units to credit Bonneville Power Administration (BPA) for providing funds to acquire the project site as partial mitigation for habitat losses associated with construction of Grand Coulee and Chief Joseph Dams. Baseline HEP surveys generated 3,857.64 habitat units or 1.16 HUs per acre. HEP surveys also served to document general habitat conditions. Survey results indicated that the herbaceous plant community lacked forbs species, which may be due to both livestock grazing and the late timing of the surveys. Moreover,more » the herbaceous plant community lacked structure based on lower than expected visual obstruction readings (VOR); likely a direct result of livestock impacts. In addition, introduced herbaceous vegetation including cultivated pasture grasses, e.g. crested wheatgrass and/or invader species such as cheatgrass and mustard, were present on most areas surveyed. The shrub element within the shrubsteppe cover type was generally a mosaic of moderate to dense shrubby areas interspersed with open grassland communities while the 'steppe' component was almost entirely devoid of shrubs. Riparian shrub and forest areas were somewhat stressed by livestock. Moreover, shrub and tree communities along the lower reaches of Nine Mile Creek suffered from lack of water due to the previous landowners 'piping' water out of the stream channel.« less

Ecophysiological aspects of the interactions between Bromus kopetdaghensis and two nurse shrubs, Astragalus meschedensis and Acantholimon raddeanam in a semiarid rangeland.

PubMed

Jankju, M; Maghamnia, A

2010-07-01

Plant-plant interactions are known as the main biotic drivers of the vegetation dynamics. Therefore, understanding such processes is beneficial for the applied vegetation management. The aim of this research was to investigate the type and intensity of plant-plant interaction during the time course of a growth season. We studied ecophysiological aspects of facilitation and competition between two aridland shrubs, A. meschedensis Bunge and A. raddeanam Czernjak and one perennial grass, B. kopetdaghensis Krasch. Soil and plant sampling were carried out for shrubs and the grass that were either growing alone or the grass was growing under the canopy of shrubs. In Spring (May), soil humidity weight was higher under the shrubs+grass than the grass-only site. By the beginning of Summer (July) grass consumed the common soil water and rapidly terminated its yearly growth. Therefore, in August and September, soil humidity weight was lower under the shrubs+grass than shrub-only sites. Photosynthesis rate of B. kopetdaghensis was sharply reduced from the beginning towards the end of growth season, but was not varied between the different plant combinations. Leaf proline measurement in July indicated higher stress for B. kopetdaghensis that were growing under shrubs than those of open areas. In conclusion, we found facilitation effects of shrubs on the grass at the early times of growth season, but it shifted into the competition for water during summer times. The outcome of plant interaction was positive for the grass but negative for the shrubs, especially A. meschedensis.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brandt, C.A.; Rickard, W.H. Jr.; Hefty, M.G.

This report describes the development of the reclamation project for the Hanford Site Near Surface Test Facility (NSTF), its implementation, and preliminary estimates of its success. The goal of the reclamation project is to return disturbed sites as nearly as practicable to their original conditions using native species. Gable Mountain is dominated by two plant communities: a big sagebrush (Artemisia tridentata) -- Sandberg's bluegrass (Poa sandbergii) community and a stiff sagebrush (Artemisia rigida) -- Sandberg's bluegrass community. Disassembly of the site installations began on March 15, 1988, and the site was returned to original contours by December 12, 1988. Twomore » separate revegetation methods were employed at the NSTF to meet differing site constraints. Vegetative cover and density in the revegetation plots were assessed in April 1989 and again in June 1989 and 1990. It is extremely unlikely that the sand pit, borrow pit, box cuts, generator pad area, or ventilation fan area will reach the reclamation objectives set for these areas within the next 50 years without further intervention. These areas currently support few living plants. Vegetation on revegetated native soils appears to be growing as expected. Vegetation growth on the main waterline is well below the objective. To date, no shrubs have grown on the area, growth of native grasses is well below the objective, and much of the area has been covered with the pit run material, which may not support adequate growth. Without further treatments, the areas without the pit run material will likely revert to a nearly pure cheatgrass condition. 44 refs., 13 figs., 7 tabs.« less

Hydrology of a zero-order Southern Piedmont watershed through 45 years of changing agricultural land use. Part 1. Monthly and seasonal rainfall-runoff relationships

NASA Astrophysics Data System (ADS)

Endale, Dinku M.; Fisher, Dwight S.; Steiner, Jean L.

2006-01-01

Few studies have reported runoff from small agricultural watersheds over sufficiently long period so that the effect of different cover types on runoff can be examined. We analyzed 45-yrs of monthly and annual rainfall-runoff characteristics of a small (7.8 ha) zero-order typical Southern Piedmont watershed in southeastern United States. Agricultural land use varied as follows: 1. Row cropping (5-yrs); 2. Kudzu ( Pueraria lobata; 5-yrs); 3. Grazed kudzu and rescuegrass ( Bromus catharticus; 7-yrs); and 4. Grazed bermudagrass and winter annuals ( Cynodon dactylon; 28-yrs). Land use and rainfall variability influenced runoff characteristics. Row cropping produced the largest runoff amount, percentage of the rainfall partitioned into runoff, and peak flow rates. Kudzu reduced spring runoff and almost eliminated summer runoff, as did a mixture of kudzu and rescuegrass (KR) compared to row cropping. Peak flow rates were also reduced during the kudzu and KR. Peak flow rates increased under bermudagrass but were lower than during row cropping. A simple process-based 'tanh' model modified to take the previous month's rainfall into account produced monthly rainfall and runoff correlations with coefficient of determination ( R2) of 0.74. The model was tested on independent data collected during drought. Mean monthly runoff was 1.65 times the observed runoff. Sustained hydrologic monitoring is essential to understanding long-term rainfall-runoff relationships in agricultural watersheds.

Uptake of explosives from contaminated soil by existing vegetation at the Joliet Army Ammunition Plant

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schneider, J.F.; Tomczyk, N.A.; Zellmer, S.D.

1994-01-01

This study examines the uptake of explosives by existing vegetation growing in TNT-contaminated soils on Group 61 at the Joliet Army Ammunition Plant (JAAP). The soils in this group were contaminated more than 40 years ago. In this study, existing plant materials and soil from the root zone were sampled from 15 locations and analyzed to determine TNT uptake by plants under natural field conditions. Plant materials were separated by species if more than one species was present at a sampling location. Standard methods were used to determine concentrations of explosives, their derivatives, and metabolites in the soil samples. Plantmore » materials were also analyzed. No. explosives were detected in the aboveground portion of any plant sample. However, the results indicate that TNT, 2-amino DNT, and/or 4-amino DNT were found in some root samples of false boneset (Kuhnia eupatorioides), teasel (Dipsacus sylvestris), and bromegrass (Bromus inermis). It is possible that slight soil contamination remained on the roots, especially in the case of the very fine roots for species like bromegrass, where washing was difficult. The presence of 2-amino DNT and 4-amino DNT, which could be plant metabolites of TNT, increases the likelihood that explosives were taken up by plant roots, as opposed to their presence resulting from external soil contamination.« less

Viral pathogen production in a wild grass host driven by host growth and soil nitrogen.

PubMed

Whitaker, Briana K; Rúa, Megan A; Mitchell, Charles E

2015-08-01

Nutrient limitation is a basic ecological constraint that has received little attention in studies on virus production and disease dynamics. Nutrient availability could directly limit the production of viral nucleic acids and proteins, or alternatively limit host growth and thus indirectly limit metabolic pathways necessary for viral replication. In order to compare direct and indirect effects of nutrient limitation on virus production within hosts, we manipulated soil nitrogen (N) and phosphorus (P) availability in a glasshouse for the wild grass host Bromus hordeaceus and the viral pathogen Barley yellow dwarf virus-PAV. We found that soil N additions increased viral concentrations within host tissues, and the effect was mediated by host growth. Specifically, in statistical models evaluating the roles of host biomass production, leaf N and leaf P, viral production depended most strongly on host biomass, rather than the concentration of either nutrient. Furthermore, at low soil N, larger plants supported greater viral concentrations than smaller ones, whereas at high N, smaller plants supported greater viral concentrations. Our results suggest that enhanced viral productivity under N enrichment is an indirect consequence of nutrient stimulation to host growth rate. Heightened pathogen production in plants has important implications for a world facing increasing rates of nutrient deposition. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

The effects of plant nutritional strategy on soil microbial denitrification activity through rhizosphere primary metabolites.

PubMed

Guyonnet, Julien P; Vautrin, Florian; Meiffren, Guillaume; Labois, Clément; Cantarel, Amélie A M; Michalet, Serge; Comte, Gilles; Haichar, Feth El Zahar

2017-04-01

The aim of this study was to determine (i) whether plant nutritional strategy affects the composition of primary metabolites exuded into the rhizosphere and (ii) the impact of exuded metabolites on denitrification activity in soil. We answered this question by analysing primary metabolite content extracted from the root-adhering soil (RAS) and the roots of three grasses representing different nutrient management strategies: conservative (Festuca paniculata), intermediate (Bromus erectus) and exploitative (Dactylis glomerata). We also investigated the impact of primary metabolites on soil microbial denitrification enzyme activity without carbon addition, comparing for each plant RAS and bulk soils. Our data show that plant nutritional strategy impacts on primary metabolite composition of root extracts or RAS. Further we show, for the first time, that RAS-extracted primary metabolites are probably better indicators to explain plant nutrient strategy than root-extracted ones. In addition, our results show that some primary metabolites present in the RAS were well correlated with soil microbial denitrification activity with positive relationships found between denitrification and the presence of some organic acids and negative ones with the presence of xylose. We demonstrated that the analysis of primary metabolites extracted from the RAS is probably more pertinent to evaluate the impact of plant on soil microbial community functioning. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Biotechnologically generating 'super chickpea' for food and nutritional security.

PubMed

Acharjee, Sumita; Sarmah, Bidyut Kumar

2013-06-01

Chickpea productivity is affected by various constraints that are biotic (Helicoverpa, Aphids, Callosobruchus, Bromus and Orobanche) and abiotic (drought and salinity). In addition, the grains of this legume are deficient in sulfur amino acids, methionine and cysteine. The possibilities for genetic improvement by marker-assisted breeding and selection approaches are limited in chickpeas due to their sexually incompatible gene pool. Transgenic chickpeas expressing either the cry1Ac/b or the cry2Aa gene and the bean α-amylase inhibitor gene are resistant to Helicoverpa and bruchids, respectively, but these chickpeas have yet to be commercialized. Unfortunately, attempts to generate transgenic chickpeas with increased tolerance to drought and salinity or with increased methionine content have been less successful. The commercialization of transgenic chickpeas containing a single transgene may not give adequate yield advantage, as chickpeas are affected by many production constraints in the field and in storage. Gene pyramiding by incorporating two or more genes may be useful because improving one trait at a time will be time-consuming, labor-intensive and costly. Use of modern multi-gene vectors that contain recognition sites for zinc finger nucleases (ZFNs) and homing endonucleases may simplify the incorporation of multiple genes into chickpeas. This approach necessitates a collaborative effort between individuals, public and private organizations to generate 'super chickpeas' that harbor multiple transgenic traits. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Plant assemblage composition and soil P concentration differentially affect communities of AM and total fungi in a semi-arid grassland.

PubMed

Klabi, Rim; Bell, Terrence H; Hamel, Chantal; Iwaasa, Alan; Schellenberg, Mike; Raies, Aly; St-Arnaud, Marc

2015-01-01

Adding inorganic P- and N-fixing legumes to semi-arid grasslands can increase forage yield, but soil nutrient concentrations and plant cover may also interact to modify soil fungal populations, impacting short- and long-term forage production. We tested the effect of plant assemblage (seven native grasses, seven native grasses + the domesticated N-fixing legume Medicago sativa, seven native grasses + the native N-fixing legume Dalea purpurea or the introduced grass Bromus biebersteinii + M. sativa) and soil P concentration (addition of 0 or 200 P2O5 kg ha(-1) at sowing) on the diversity and community structure of arbuscular mycorrhizal (AM) fungi and total fungi over two consecutive years, using 454-pyrosequencing of 18S rDNA and ITS amplicons. Treatment effects were stronger in the wet year (2008) than the dry year (2009). The presence of an N-fixing legume with native grasses generally increased AM fungal diversity, while the interaction between soil P concentration and plant assemblage modified total fungal community structure in 2008. Excluding interannual variations, which are likely driven by moisture and plant productivity, AM fungal communities in semi-arid grasslands appear to be primarily affected by plant assemblage composition, while the composition of other fungi is more closely linked to soil P. © FEMS 2014. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

A comparative study of AMF diversity in annual and perennial plant species from semiarid gypsum soils.

NASA Astrophysics Data System (ADS)

Alguacil, M. M.; Torrecillas, E.; Roldán, A.; Díaz, G.; Torres, P.

2012-04-01

The arbuscular mycorrhizal fungi (AMF) communities composition regulate plant interactions and determine the structure of plant communities. In this study we analysed the diversity of AMF in the roots of two perennial gypsophyte plant species, Herniaria fruticosa and Senecio auricula, and an annual herbaceous species, Bromus rubens, growing in a gypsum soil from a semiarid area. The objective was to determine whether perennial and annual host plants support different AMF communities in their roots and whether there are AMF species that might be indicators of specific functional plant roles in these ecosystems. The roots were analysed by nested PCR, cloning, sequencing of the ribosomal DNA small subunit region and phylogenetic analysis. Twenty AMF sequence types, belonging to the Glomus group A, Glomus group B, Diversisporaceae, Acaulosporaceae, Archaeosporaceae and Paraglomeraceae, were identified. Both gypsophyte perennial species had differing compositions of the AMF community and higher diversity when compared with the annual species, showing preferential selection by specific AMF sequences types. B. rubens did not show host specificity, sharing the full composition of its AMF community with both perennial plant species. Seasonal variations in the competitiveness of AM fungi could explain the observed differences in AMF community composition, but this is still a working hypothesis that requires the analysis of further data obtained from a higher number of both annual and perennial plant species in order to be fully tested.

A leachate a day keeps the seedlings away: mowing and the inhibitory effects of Festuca paniculata in subalpine grasslands

PubMed Central

Viard-Crétat, Flore; Gallet, Christiane; Lefebvre, Marianne; Lavorel, Sandra

2009-01-01

Background and Aims Is the release of allelochemicals by the dominant tussock grass Festuca paniculata responsible for its dominance by inhibiting growth of neighbour grasses in subalpine grasslands? As such a community is also structured by mowing practices, what could be the impact of mowing on allelopathy? Methods A design was used that isolated allelopathy from resource competition by separating donor plants (Festuca paniculata) from target plants (F. paniculata, Dactylis glomerata and Bromus erectus). Leachates from donor pots containing bare soil, unmown F. paniculata or mown F. paniculata continuously irrigated target pots containing seedlings. Activated carbon was added in half of the target pots to adsorb potential allelochemicals. C and N analyses of target potting soil were used to test for any effect of treatments on resources. Total phenol concentration was measured in the solutions flowing from donor to target pots. Results Festuca paniculata leachates inhibited seedling growth of D. glomerata and B. erectus. Inhibition was correlated with polyphenol concentration, and was not due to resource competition for nitrogen. Mowing the leaves of the donor plants did not significantly increase this inhibition. The activated carbon treatment was not conclusive as it inhibited the seedling growing under control pots with only bare soil. Conclusions The results suggest that allelopathy may be at least partly responsible for F. paniculata dominance in subalpine meadows by inhibition of colonization by neighbouring species. PMID:19324898

Home range and habitat use by Great Horned Owls (Bubo virginianus) in Southern California

USGS Publications Warehouse

Bennett, J.R.; Bloom, P.H.

2005-01-01

Great Horned Owls (Bubo virginianus) are a common, widespread species that can be found in a variety of habitats across most of North America, but little is known about their space and habitat requirements. Using radiotelemetry, location data were collected on nine male and five female Great Horned Owls to determine home range and habitat use in southern California. Owls were tracked between January 1997 and September 1998 for periods ranging from 5-17 mo. Seven owls were also followed during 13 all-night observation periods. The mean 95% adaptive kernel home-range size for females was 180 ha (range = 88-282, SE = 36) and that for males was 425 ha (range = 147-1115 ha, SE = 105). Core areas estimated by the 50% adaptive kernel averaged 27 ha (range = 7-44, SE = 7) for females and 61 ha (range = 15-187, SE = 18) for males. Owls were located in areas with varying degrees of human disturbance ranging from almost entirely urban to native oak (Quercus agrifolia) woodland. Oak/sycamore (Quercus agrifolia/Platanus racemosa) woodland and ruderal grassland (Bromus spp., Avena spp., and various other non-native invasives), were used more often than expected based on availability, but we found no correlation between home-range size and any single habitat type or habitat groups. ?? 2005 The Raptor Research Foundation, Inc.

Comparison of Carbon Sequestration Rates and Energy Balance of Turf in the Denver Urban Ecosystem and an Adjacent Native Grassland

NASA Astrophysics Data System (ADS)

Thienelt, T. S.; Anderson, D. E.; Powell, K. M.

2011-12-01

Urban ecosystems are currently characterized by rapid growth, are expected to continually expand and, thus, represent an important driver of land use change. A significant component of urban ecosystems is lawns, potentially the single largest irrigated "crop" in the U.S. Beginning in March of 2011 (ahead of the growing season), eddy covariance measurements of net carbon exchange and evapotranspiration along with energy balance fluxes were conducted for a well-watered, fertilized lawn (rye-bluegrass-mix) in metropolitan Denver and for a nearby tallgrass prairie (big bluestem, switchgrass, cheatgrass, blue grama). Due to the semi-arid climate conditions of the Denver region, differences in management (i.e., irrigation and fertilization) are expected to have a discernible impact on ecosystem productivity and thus on carbon sequestration rates, evapotranspiration, and the sensible and latent heat partitioning of the energy balance. By mid-July, preliminary data indicated that cumulative evapotranspiration was approximately 270 mm and 170 mm for urban and native grasslands, respectively, although cumulative carbon sequestration at that time was similar for both (approximately 40 mg/m2). However, the pattern of carbon exchange differed between the grasslands. Both sites showed daily net uptake of carbon starting in late May, but the urban lawn displayed greater diurnal variability as well as greater uptake rates in general, especially following fertilization in mid-June. In contrast, the trend of carbon uptake at the prairie site was occasionally reversed following strong convective precipitation events, resulting in a temporary net release of carbon. The continuing acquisition of data and investigation of these relations will help us assess the potential impact of urban growth on regional carbon sequestration.

Shrubs as ecosystem engineers across an environmental gradient: effects on species richness and exotic plant invasion.

PubMed

Kleinhesselink, Andrew R; Magnoli, Susan M; Cushman, J Hall

2014-08-01

Ecosystem-engineering plants modify the physical environment and can increase species diversity and exotic species invasion. At the individual level, the effects of ecosystem engineers on other plants often become more positive in stressful environments. In this study, we investigated whether the community-level effects of ecosystem engineers also become stronger in more stressful environments. Using comparative and experimental approaches, we assessed the ability of a native shrub (Ericameria ericoides) to act as an ecosystem engineer across a stress gradient in a coastal dune in northern California, USA. We found increased coarse organic matter and lower wind speeds within shrub patches. Growth of a dominant invasive grass (Bromus diandrus) was facilitated both by aboveground shrub biomass and by growing in soil taken from shrub patches. Experimental removal of shrubs negatively affected species most associated with shrubs and positively affected species most often found outside of shrubs. Counter to the stress-gradient hypothesis, the effects of shrubs on the physical environment and individual plant growth did not increase across the established stress gradient at this site. At the community level, shrub patches increased beta diversity, and contained greater rarified richness and exotic plant cover than shrub-free patches. Shrub effects on rarified richness increased with environmental stress, but effects on exotic cover and beta diversity did not. Our study provides evidence for the community-level effects of shrubs as ecosystem engineers in this system, but shows that these effects do not necessarily become stronger in more stressful environments.

Dominance and environmental correlates of alien annual plants in the Mojave Desert, USA

USGS Publications Warehouse

Brooks, M.L.; Berry, K.H.

2006-01-01

Land managers are concerned about the negative effects of alien annual plants on native plants, threatened and endangered species such as the desert tortoise (Gopherus agassizii), and ecosystem integrity in the Mojave Desert. Management of alien plants is hampered by a lack of information regarding the dominance and environmental correlates of these species. The results of this study indicate that alien plant species comprised a small fraction of the total annual plant flora, but most of the annual plant community biomass. When rainfall was high in 1995, aliens comprised 6% of the flora and 66% of the biomass. When rainfall was low in 1999, aliens comprised 27% of the flora and 91% of the biomass. Bromus rubens, Schismus spp. (S. arabicus and S. barbatus), and Erodium cicutarium were the predominant alien species during both years, comprising 99% of the alien biomass. B. rubens was more abundant in relatively mesic microhabitats beneath shrub canopies and at higher elevations above 800-1000 m, whereas Schismus spp. and E. cicutarium were more abundant in the relatively arid interspaces between shrubs, and, for Schismus spp., at lower elevations as well. Disturbance variables were more reliable indicators of alien dominance than were productivity or native plant diversity variables, although relationships often varied between years of contrasting rainfall. The strongest environmental correlates occurred between dirt road density and alien species richness and biomass of E. cicutarium, and between frequency and size of fires and biomass of B. rubens.

Effects of competition on induction of crassulacean acid metabolism in a facultative CAM plant.

PubMed

Yu, Kailiang; D'Odorico, Paolo; Li, Wei; He, Yongli

2017-06-01

Abiotic drivers of environmental stress have been found to induce CAM expression (nocturnal carboxylation) in facultative CAM species such as Mesembryanthemum crystallinum. The role played by biotic factors such as competition with non-CAM species in affecting CAM expression, however, remains largely understudied. This research investigated the effects of salt and water conditions on the competition between M. crystallinum and the C 3 grass Bromus mollis with which it is found to coexist in California's coastal grasslands. We also investigated the extent to which CAM expression in M. crystallinum was affected by the intensity of the competition with B. mollis. We found that M. crystallinum had a competitive advantage over B. mollis in drought and saline conditions, while B. mollis exerted strong competitive effects on M. crystallinum in access to light and soil nutrients in high water conditions. This strong competitive effect even outweighed the favorable effects of salt or water additions in increasing the biomass and productivity of M. crystallinum in mixture. Regardless of salt conditions, M. crystallinum did not switch to CAM photosynthesis in response to this strong competitive effect from B. mollis. Disturbance (i.e., grass cutting) reduced the competitive pressure by B. mollis and allowed for CAM expression in M. crystallinum when it was grown mixed with B. mollis. We suggest that moderate competition with other functional groups can enhance CAM expression in M. crystallinum, thereby affecting its plasticity and ability to cope with biological stress.

An adaptive approach to invasive plant management on U.S. Fish and Wildlife Service-owned native prairies in the Prairie Pothole Region: decision support under uncertainity

USGS Publications Warehouse

Gannon, Jill J.; Moore, Clinton T.; Shaffer, Terry L.; Flanders-Wanner, Bridgette

2011-01-01

Much of the native prairie managed by the U.S. Fish and Wildlife Service (Service) in the Prairie Pothole Region (PPR) is extensively invaded by the introduced cool-season grasses smooth brome (Bromus inermis) and Kentucky bluegrass (Poa pratensis). The central challenge to managers is selecting appropriate management actions in the face of biological and environmental uncertainties. We describe the technical components of a USGS management project, and explain how the components integrate and inform each other, how data feedback from individual cooperators serves to reduce uncertainty across the whole region, and how a successful adaptive management project is coordinated and maintained on a large scale. In partnership with the Service, the U.S. Geological Survey is developing an adaptive decision support framework to assist managers in selecting management actions under uncertainty and maximizing learning from management outcomes. The framework is built around practical constraints faced by refuge managers and includes identification of the management objective and strategies, analysis of uncertainty and construction of competing decision models, monitoring, and mechanisms for model feedback and decision selection. Nineteen Service field stations, spanning four states of the PPR, are participating in the project. They share a common management objective, available management strategies, and biological uncertainties. While the scope is broad, the project interfaces with individual land managers who provide refuge-specific information and receive updated decision guidance that incorporates understanding gained from the collective experience of all cooperators.

Habitat associations of vertebrate prey within the controlled area study zone

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marr, N.V.; Brandt, C.A.; Fitzner, R.E.

1988-03-01

Twelve study locations were established in nine habitat types in the vicinity of the proposed reference repository location. Eight species of small mammals were captured. Great Basin pocket mice (Perognathus parvus) comprised the majority of individuals captured, followed by deer mice (Peromyscus maniculatus), Northern pocket gopher (Thomomys talpoides), Western harvest mouse (Reithrodontomys megalotus), Grasshopper mouse (Onychomys leucogaster), Montane vole, (Microtus montanus), House mouse (Mus musculus), and the Bushy-tailed woodrat (Neotoma cinerea). Pocket mice were captured in all habitats sampled; deer mice were obtained in all habitats save hopsage and nearly pure cheatgrass stands. The highese capture rates were found inmore » bitterbrush and riparian habitats. Capture sex ratios for both pocket mice and deer mice were significantly different from equality. Body weights for deer mice and pocket mice exhibited a great deal of heterogeneity across trap sites, although only the heterogeneity for pocket mice was significant. In general, body weights for both species were greater in the sagebrush habitats than elsewhere. These differences are interpreted in light of habitat evaluation methodologies. Six species of reptiles and one species of amphibian were captured. Side-blotched lizards (Uta stansburiana) were by far the most frequently captured species. The predominant snakes captured were the yellow-bellied racer (Coluber constrictor) and the Great Basin gopher snake (Pituophis melanoleucus). Two Great Basin spadefoot toads (Scaphiopus intermontanus) captured at the Rattlesnake Springs trap site. Species diversity was quite low (Shannon-Wiener H )equals) 1.03). Side-blotched lizards were found in all habitats save near the talus on Gable Mountain and on the gravel pad site. The only other lizard species (northern sagebrush lizard (Sceloporus graciosus) and short-horned lizard (Phrynosoma douglasii)) were obtained in bitterbrush habitat. 20 refs., 1 fig

A synopsis of short-term response to alternative restoration treatments in sagebrush-steppe: the SageSTEP project

USGS Publications Warehouse

McIver, James; Brunson, Mark; Bunting, Steve; Chambers, Jeanne; Doescher, Paul; Grace, James; Hulet, April; Johnson, Dale; Knick, Steven T.; Miller, Richard; Pellant, Mike; Pierson, Fred; Pyke, David; Rau, Benjamin; Rollins, Kim; Roundy, Bruce; Schupp, Eugene; Tausch, Robin; Williams, Jason

2014-01-01

best chance managers have for arresting woodland expansion and cheatgrass invasion that may accelerate in a future warming climate.

Evaluating Current and Future Rangeland Health in the Great Basin Ecoregion Using NASA Earth Observing Systems

NASA Astrophysics Data System (ADS)

Essoudry, E.; Wilson, K.; Ely, J.; Patadia, N.; Zajic, B.; Torres-Perez, J. L.; Schmidt, C.

2014-12-01

The Great Basin ecoregion in the western United States represents one of the last large expanses of wild lands in the nation and is currently facing significant challenges due to human impacts, drought, invasive species encroachment such as cheatgrass, and climate change. Rangelands in the Great Basin are of important ecological and economic significance for the United States; however, 40% of public rangelands fail to meet required health standards set by the Bureau of Land Management (BLM). This project provided a set of assessment tools for researchers and land managers that integrate remotely-sensed and in situ datasets to quantify and mitigate threats to public lands in the Great Basin ecoregion. The study area, which accounts for 20% of the total Great Basin ecoregion, was analyzed using 30 m resolution data from Landsat 8. Present conditions were evaluated from vegetation indices, landscape features, hydrological processes, and atmospheric conditions derived from the remotely-sensed data and validated with available in situ ground survey data, provided by the BLM. Rangeland health metrics were developed and landscape change drivers were identified. Subsequently, projected climate conditions derived from the Coupled Model Intercomparison Project (CMIP5) were used to forecast the impact of changing climatic conditions within the study area according to the RCP4.5 and RCP8.5 projections. These forecasted conditions were used in the Maximum Entropy Model (MaxEnt) to predict areas at risk for rangeland degradation on 30 year intervals for 2040, 2070, and 2100. Finally, vegetation health risk maps were provided to the project partners to aid in future land management decisions in the Great Basin ecoregion. These tools provide a low cost solution to assess landscape conditions, provide partners with a metric to identify potential problematic areas, and mitigate serious threats to the ecosystems.

Allelopathic cover crop prior to seeding is more important than subsequent grazing/mowing in Grassland establishment

USGS Publications Warehouse

Milchunas, D.G.; Vandever, M.W.; Ball, L.O.; Hyberg, S.

2011-01-01

The effects of grazing, mowing, and type of cover crop were evaluated in a previous winter wheat-fallow cropland seeded to grassland under the Conservation Reserve Program in eastern Colorado. Prior to seeding, the fallow strips were planted to forage sorghum or wheat in alternating strips (cover crops), with no grazing, moderate to heavy grazing, and mowing (grazing treatments) superimposed 4 yr after planting and studied for 3 yr. Plots previously in wheat had more annual and exotic species than sorghum plots. Concomitantly, there were much greater abundances of perennial native grass and all native species in sorghum than wheat cropped areas. The competitive advantage gained by seeded species in sorghum plots resulted in large increases in rhizomatous western wheatgrass. Sorghum is known to be allelopathic and is used in crop agriculture rotations to suppress weeds and increase crop yields, consistent with the responses of weed and desired native species in this study. Grazing treatment had relatively minor effects on basal and canopy cover composition of annual or exotic species versus perennial native grass or native species. Although grazing treatment never was a significant main effect, it occasionally modified cover crop or year effects. Opportunistic grazing reduced exotic cheatgrass by year 3 but also decreased the native palatable western wheatgrass. Mowing was a less effective weed control practice than grazing. Vegetative basal cover and aboveground primary production varied primarily with year. Common management practices for revegetation/restoration currently use herbicides and mowing as weed control practices and restrict grazing in all stages of development. Results suggest that allelopathic cover crop selection and opportunistic grazing can be effective alternative grass establishment and weed control practices. Susceptibility, resistance, and interactions of weed and seeded species to allelopathic cover species/cultivars may be a fruitful area of

Allelopathic cover crop prior to seeding is more important than subsequent grazing/mowing in grassland establishment

USGS Publications Warehouse

Milchunas, Daniel G.; Vandever, Mark W.; Ball, Leonard O.; Hyberg, Skip

2011-01-01

The effects of grazing, mowing, and type of cover crop were evaluated in a previous winter wheat–fallow cropland seeded to grassland under the Conservation Reserve Program in eastern Colorado. Prior to seeding, the fallow strips were planted to forage sorghum or wheat in alternating strips (cover crops), with no grazing, moderate to heavy grazing, and mowing (grazing treatments) superimposed 4 yr after planting and studied for 3 yr. Plots previously in wheat had more annual and exotic species than sorghum plots. Concomitantly, there were much greater abundances of perennial native grass and all native species in sorghum than wheat cropped areas. The competitive advantage gained by seeded species in sorghum plots resulted in large increases in rhizomatous western wheatgrass. Sorghum is known to be allelopathic and is used in crop agriculture rotations to suppress weeds and increase crop yields, consistent with the responses of weed and desired native species in this study. Grazing treatment had relatively minor effects on basal and canopy cover composition of annual or exotic species versus perennial native grass or native species. Although grazing treatment never was a significant main effect, it occasionally modified cover crop or year effects. Opportunistic grazing reduced exotic cheatgrass by year 3 but also decreased the native palatable western wheatgrass. Mowing was a less effective weed control practice than grazing. Vegetative basal cover and aboveground primary production varied primarily with year. Common management practices for revegetation/restoration currently use herbicides and mowing as weed control practices and restrict grazing in all stages of development. Results suggest that allelopathic cover crop selection and opportunistic grazing can be effective alternative grass establishment and weed control practices. Susceptibility, resistance, and interactions of weed and seeded species to allelopathic cover species/cultivars may be a fruitful area

Influence of richness and seeding density on invasion resistance in experimental tallgrass prairie restorations

USGS Publications Warehouse

Nemec, Kristine T.; Allen, Craig R.; Helzer, Christopher J.; Wedin, David A.

2013-01-01

In recent years, agricultural producers and non-governmental organizations and agencies have restored thousands of hectares of cropland to grassland in the Great Plains of the United States. However, little is known about the relationships between richness and seeding density in these restorations and resistance to invasive plant species. We assessed the effects of richness and seeding density on resistance to invasive and other unseeded plant species in experimental tallgrass prairie plots in central Nebraska. In 2006, twenty-four 55 m × 55 m plots were planted with six replicates in each of four treatments: high richness (97 species typically planted by The Nature Conservancy), at low and high seeding densities, and low richness (15 species representing a typical Conservation Reserve Program mix, CP25), at low and high seeding densities. There was a significant negative relationship between richness and basal cover of unseeded perennial forbs/legumes and unseeded perennial/annual grasses, abundance of bull thistle (Cirsium vulgare), and the number of inflorescences removed from smooth brome (Bromus inermis) transplants. Invasion resistance may have been higher in the high richness treatments because of the characteristics of the dominant species in these plots or because of greater interspecific competition for limiting resources among forbs/legumes with neighboring plants belonging to the same functional group. Seeding density was not important in affecting invasion resistance, except in the cover of unseeded grasses. Increasing seed mix richness may be more effective than increasing the seeding density for decreasing invasion by unseeded perennial species, bull thistle, and smooth brome.

The effect of different land uses on arbuscular mycorrhizal fungi in the northwestern Black Sea Region.

PubMed

Palta, Şahin; Lermi, Ayşe Genç; Beki, Rıdvan

2016-06-01

The object of the present research was to establish correlations between the status of root colonization of arbuscular mycorrhizal fungi (AMF) and different types of land use. In order to achieve this aim, rhizosphere soil samples from grassland crops were taken during June and July of 2013 in order to use for determining several soil characteristics. The 27 different taxa and 60 soil samples were collected from the rhizosphere level in the study areas. The existence of AMF was confirmed in 100 % of these plants with different rations of colonization (approximately 12-89 %). Bromus racemosus L. (pasture) was the most dense taxon with the percentage of AMF colonization of 88.9 %, and Trifolium pratense L. (forest) was the least dense taxon with the percentage of AMF colonization of 12.2 % (average 52.0 %). As a result of the statistical analysis, a positive relationship was found between the botanical composition of legumes and AMF colonization (r = 0.35; p = 0.006). However, a negative relationship was determined between botanical composition of other plant families and AMF colonization (r = -0.39; p = 0.002). In addition, a positive relationship was defined between soil pH (H2O) and the root colonization of AMF (r = 0.35; p = 0.005). The pasture had the highest mean value of AMF root colonization. However, the pasture and gap in the forest were in the same group, according to the results of the S-N-K test.

Maternal experience and soil origin influence interactions between resident species and a dominant invasive species.

PubMed

Stotz, Gisela C; Gianoli, Ernesto; Cahill, James F

2018-01-01

Invasive species dominance in invaded communities may not be long-lasting due to regulatory processes, such as plant-soil feedbacks and neighboring species adaptation. Further, the change in species competitive ability may be contingent upon neighbor identity (i.e., specialized response) or consistent across neighbors (i.e., generalized response). Specialized responses can facilitate overall coexistence, while generalized responses may result in competitive exclusion. We set up a greenhouse experiment to test, in three species, the effect of soil conditions (non-invaded vs. invaded soil) and maternal experience (offspring of maternal plants from invaded vs. non-invaded areas) on species competitive ability against the invader Bromus inermis and conspecifics. If changes in species competitive ability against B. inermis were also evident when interacting with conspecifics, it would suggest a generalized increased/decreased competitive ability. Maternal experience resulted in reduced suppression of B. inermis in the three species and no change in tolerance. On the other hand, tolerance to B. inermis was enhanced when plants grew in soil from invaded areas, compared to non-brome soil. Importantly, both the decreased suppression due to maternal experience with B. inermis and the increased tolerance in invaded soil appear to be invader specific, as no such effects were observed when interacting with conspecifics. Specialized responses should facilitate coexistence, as no individual/species is a weaker or stronger competitor against all other neighbors or under all local soil conditions. Further, the negative plant-soil feedback for B. inermis should facilitate native species recovery in invaded areas and result in lower B. inermis performance and dominance over time.

Accumulation of HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) in indigenous and agricultural plants grown in HMX-contaminated anti-tank firing-range soil.

PubMed

Groom, Carl A; Halasz, Annamaria; Paquet, Louise; Morris, Neil; Olivier, Lucie; Dubois, Charles; Hawari, Jalal

2002-01-01

To investigate their potential for phytoremediation, selected agricultural and indigenous terrestrial plants were examined fortheir capacity to accumulate and degrade the explosive octahydro-1 ,3,5,7-tetra nitro-1,3,5,7-tetrazocine (HMX). Plant tissue and soil extracts were analyzed for the presence of HMX and possible degradative metabolites using high-performance liquid chromatography with diode-array UV detection (HPLC-UV), micellar electrokinetic chromatography with diode-array UV detection (MEKC-UV), and HPLC with electrospray ionization mass spectrometry (LC-MS). The pattern of HMX accumulation for alfalfa (Medicago sativa), bush bean (Phaseolus vulgaris), canola (Brassica rapa), wheat (Triticum aestivum), and perennial ryegrass (Loliumperenne) grown in a controlled environment on contaminated soil from an anti-tank firing range was similar to that observed for plants (wild bergamot (Monarda fistulosa), western wheat grass (Agropyron smithii), brome grass (Bromus sitchensis), koeleria (Koeleria gracilis), goldenrod (Solidago sp.), blueberry (Vaccinium sp.), anemone (Anemone sp.), common thistle (Circium vulgare), wax-berry (Symphoricarpos albus), western sage (Artemisia gnaphalodes), and Drummond's milk vetch (Astragalus drummondii)) collected from the range. No direct evidence of plant-mediated HMX (bio)chemical transformation was provided by the available analytical methods. Traces of mononitroso-HMX were found in contaminated soil extracts and were also observed in leaf extracts. The dominant mechanism for HMX translocation and accumulation in foliar tissue was concluded to be aqueous transpirational flux and evaporation. The accumulation of HMX in the leaves of most of the selected species to levels significantly above soil concentration is relevant to the assessment of both phytoremediation potential and environmental risks.

Persistence of native and exotic plants 10 years after prairie reconstruction

USGS Publications Warehouse

Larson, Diane L.; Bright, J. B.; Drobney, Pauline; Larson, Jennifer L.; Vacek, Sara

2017-01-01

Prairie reconstructions are a critical component of preservation of the imperiled tallgrass prairie ecosystem in the Midwestern United States. Sustainability of this endeavor depends on establishment of persistent cover of planted native species and resistance to noxious weeds. The goal of this study was to understand the influence of early reconstruction practices on long-term outcomes. Twelve replicates of three planting methods (dormant-season broadcast, growing-season broadcast, and growing-season drill) and three seed mix richness levels (10, 20, or 34 species), fully crossed in a completely randomized design were planted in 2005 on nine former agricultural fields located in Iowa and Minnesota. Cover by species was estimated in 2005–2007, 2010, and 2015. In 2015, cover of planted species, native nonplanted species, and exotic species were similar to those recorded in 2010. Cover of the noxious weed Cirsium arvense had also declined by an average of 49% without herbicide from a peak in 2007 to low stable levels from 2010 to 2015. Richness of planted forbs, on the other hand, were still increasing in high-richness broadcast treatments (e.g. 17–59% increase 2010–1015 in Minnesota). Two results in 2015 are reasons for concern: cover of planted species is only slightly over 50% in both Minnesota and Iowa, though with forbs still increasing, this may improve; and the cool-season exotic grasses Poa pratensis and Bromus inermis are increasing at both Minnesota and Iowa sites. Control of these invasive grasses will be necessary, but care will be needed to avoid negative impacts of control methods on natives.

Effect of different forage species on the nitrogen uptake in Hulunbeir

NASA Astrophysics Data System (ADS)

Xu, Li-Jun; Xu, Xing-Liang; Tang, Xue-Juan; Yang, Gui-Xia; Zhang, Zhao; Xin, Xiao-Ping

2017-02-01

Knowledge of determining factors for nitrogen uptake preferences and how they are modified in changing environments are critical to understand ecosystem nitrogen cycling and to predict plant responses to future environmental changes. However, it remains unclear in this aspect for the main managed grassland (Medicago sativa, Bromus inermis, Leymus chinensis) and crop (Brassica campestris) under field condition in Hulunbeir area of Inner Mongolia of China. Two 15N tracer experiments utilizing a unique differential labelled nitrogen source were employed in both managed grassland (M. sativa, B. inermis and L. chinensis) and crop (B. campestris) in Hulunbeir area of Inner Mongolia of China. Tracing both labels in the above-and below ground plant biomass, soil NH4 + -N or NO3 - -N and NH4 + -N or NO3 - -N uptake by plants. There were differences between soil NO3 --N concentration and NH4+-N concentration, and NO3 --N concentration was higher than NH4 +-N concentration. NO3 --N concentration was led by different grass species. The NH4 +-N concentration in August were higher than in July on the whole, the highest value for B. campestris and the lowest for B. inermis. The plant N concentration in B. inermis, L. chinensis and B. campestris showed decreasing trend, its mean value decreased by 20.1, 47.9 and 26.7%, respectively, and M. sativa increased by 13.7%. Among the four species, the individuals exhibited a preference for 15NO3 -, indicated by higher 15N signatures in 15NO3-treatment than in 15NH4 + treatment.

Germination behaviour of annual plants under changing climatic conditions: separating local and regional environmental effects.

PubMed

Petrů, Martina; Tielbörger, Katja

2008-04-01

The role of local adaptation and factors other than climate in determining extinction probabilities of species under climate change has not been yet explicitly studied. Here we performed a field experiment with annual plants growing along a steep climatic gradient in Israel to isolate climatic effects for local trait expression. The focus trait was seed dormancy, for which many theoretical predictions exist regarding climate-driven optimal germination behaviour. We evaluated how germination is consistent with theory, indicating local adaptation to current and changing climatic conditions, and how it varies among species and between natural and standardised soil conditions. We reciprocally sowed seeds from three or four origins for each of three annual species, Biscutella didyma, Bromus fasciculatus and Hymenocarpos circinnatus, in their home and neighbouring sowing locations along an aridity gradient. Our predictions were: lower germination fraction for seeds from more arid origins, and higher germination at wetter sowing locations for all seed origins. By sowing seeds in both local and standard soil, we separated climatic effects from local conditions. At the arid sowing location, two species supported the prediction of low germination of drier seed origins, but differences between seed origins at the other sites were not substantial. There were no clear rainfall effects on germination. Germination fractions were consistently lower on local soil than on standard soil, indicating the important role of soil type and neighbour conditions for trait expression. Local environmental conditions may override effects of climate and so should be carefully addressed in future studies testing for the potential of species to adapt or plastically respond to climate change.

Preparation, characterization and in vitro/vivo evaluation of tectorigenin solid dispersion with improved dissolution and bioavailability.

PubMed

Shuai, Shuping; Yue, Shanlan; Huang, Qingting; Wang, Wei; Yang, Junyi; Lan, Ke; Ye, Liming

2016-08-01

The purpose of this study was to develop and evaluate a novel amorphous solid dispersion system for tectorigenin (TG). TG is one of isoflavone aglycones extracted from Iris tectorum and flowers of Pueraria thunbergiana, but its poor water solubility and low membrane permeability have severely restricted the clinical application. To increase the aqueous solubility and oral bioavailability of TG, we prepared the solid dispersions of tectorigenin (TG-SD) using a simple solvent evaporation process with TG, polyvinylpyrrolidone (PVP) and PEG4000 at weight ratio of 7:54:9 after tested in several ratios. The prepared solid dispersions of tectorigenin are duly characterized for drug morphological conversion, in vitro dissolution and in vivo bioavailability. The X-ray diffraction (XRD), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) studies have indicated the morphological conversion of tectorigenin to amorphous form. In vitro release profiles revealed that the % release of TG-SD was achieved 4.35-fold higher than that of the pure drug after 150 min. The oral bioavailability of the solid dispersion in rats was also increased based on AUC0-t and C max of TG-SD, which were 4.8- and 13.1-fold higher than that of TG crystal, respectively. It is worth noting that physical mixture containing TG, PEG4000 and PVP produced a similar level of oral exposure as TG-SD, suggesting that PEG4000 and PVP were able to enhance bioavailability of TG in rats. However, with the reduction of particle size, TG-SD provided the fastest oral absorption compared to physical mixture and pure drug. These results demonstrated that the efficacy of solid dispersions for the enhancement of TG oral bioavailability was by increasing its aqueous solubility and the solid dispersion formulation could be a viable option for enhancing the oral bioavailability of TG.

Aspen (Populus tremuloides Michx.) intake and preference by mammalian herbivores: the role of plant secondary compounds and nutritional context.

PubMed

Villalba, Juan J; Burritt, Elizabeth A; St Clair, Samuel B

2014-10-01

Aspen (Populus tremuloides Michx.) has evolved a chemical defense system comprised of phenolic glycosides (PG), which effectively deter insect herbivory. However, much less is known about the role of PG and the nutritional quality of the associated plant community on aspen browse susceptibility to mammalian herbivores. In three successive periods during the growing season, we conducted experiments with sheep by offering leaves from two aspen stands with different concentrations of PG (LOW, HIGH) or aspen leaves vs. leaves from a forb (Utah pea, Lathyrus pauciflorus) or a grass (smooth brome, Bromus inermis Leyss.) growing in an aspen understory. Intake of aspen (19 to 35 % PG) was low in all periods (1 to 6 g/Kg(0.75) in 2 hr) supporting the notion that aspen's defense system may contribute to its ecological success. However, lambs ate larger amounts of LOW than of HIGH suggesting that sheep could discriminate between aspen stands with different concentrations of PG, even when both stands were relatively well defended. Concentration of nutrients and chemical defenses in aspen leaves remained fairly stable across the growing season, and preference for aspen increased over the growing season. In contrast, preference for the forb and the grass decreased across the growing season in concert with a decline in the nutritional quality of these plants. The data suggest that nutritional context of aspen and associated forage species drove preference more than contrasts in defense chemistry of aspen. There may be periods of "susceptibility" of aspen use by mammalian herbivores, despite high concentrations of chemical defenses, which can potentially be targeted by management to reduce aspen herbivory.

Archaea and bacteria mediate the effects of native species root loss on fungi during plant invasion.

PubMed

Mamet, Steven D; Lamb, Eric G; Piper, Candace L; Winsley, Tristrom; Siciliano, Steven D

2017-05-01

Although invasive plants can drive ecosystem change, little is known about the directional nature of belowground interactions between invasive plants, native roots, bacteria, archaea and fungi. We used detailed bioinformatics and a recently developed root assay on soils collected in fescue grassland along a gradient of smooth brome (Bromus inermis Leyss) invasion to examine the links between smooth brome shoot litter and root, archaea, bacteria and fungal communities. We examined (1) aboveground versus belowground influences of smooth brome on soil microbial communities, (2) the importance of direct versus microbe-mediated impacts of plants on soil fungal communities, and (3) the web of roots, shoots, archaea, bacteria and fungi interactions across the A and B soil horizons in invaded and non-invaded sites. Archaea and bacteria influenced fungal composition, but not vice versa, as indicated by redundancy analyses. Co-inertia analyses suggested that bacterial-fungal variance was driven primarily by 12 bacterial operational taxonomic units (OTUs). Brome increased bacterial diversity via smooth brome litter in the A horizon and roots in the B horizon, which then reduced fungal diversity. Archaea increased abundance of several bacterial OTUs, and the key bacterial OTUs mediated changes in the fungi's response to invasion. Overall, native root diversity loss and bacterial mediation were more important drivers of fungal composition than were the direct effects of increases in smooth brome. Critically, native plant species displacement and root loss appeared to be the most important driver of fungal composition during invasion. This causal web likely gives rise to the plant-fungi feedbacks, which are an essential factor determining plant diversity in invaded grassland ecosystems.

Leaf Photosynthesis and Plant Competitive Success in a Mixed-grass Prairie: With Reference to Exotic Grasses Invasion

DOE PAGES

Dong, Dr. Xuejun; Patton, J.; Gu, Lianhong; ...

2014-11-26

The widespread invasion of exotic cool-season grasses in mixed-grass rangeland is diminishing the hope of bringing back the natural native plant communities. However, ecophysiological mechanisms explaining the relative competitiveness of these invasive grasses over the native species generally are lacking. In this study, we used experimental data collected in south-central North Dakota, USA to address this issue. Photosynthetic potential was obtained from the net assimilation (A) vs. internal CO 2 (Ci) response curves from plants grown in a greenhouse. Plant success was defined as the average frequency measured over 25 years (1988 to 2012) on overflow range sites across fivemore » levels of grazing intensity. In addition, estimated leaf area index of individual species under field conditions was used to indicate plant success. The correlation between photosynthetic potential based on A/Ci curves and plant frequency was negative. The correlation between leaf photosynthesis and plant success (defined as leaf area within a unit land area) was also negative, although statistically weak. These results suggest that the two cool-season grasses, Poa pratensis and Bromus inermis, do not rely on superior leaf-level photosynthesis for competitive success. Instead, some other traits, such as early and late-season growth, may be more important for them to gain dominance in the mixed-grass prairie. We propose that the negative photosynthesis-frequency relation as observed in this study results from a strong competition for limited soil nutrients in the mixed-grass prairie. In conclusion, it has implications for the stability and productivity of the grassland under various human disruptions influencing the soil nutrient status.« less

Leaf Photosynthesis and Plant Competitive Success in a Mixed-grass Prairie: With Reference to Exotic Grasses Invasion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dong, Dr. Xuejun; Patton, J.; Gu, Lianhong

The widespread invasion of exotic cool-season grasses in mixed-grass rangeland is diminishing the hope of bringing back the natural native plant communities. However, ecophysiological mechanisms explaining the relative competitiveness of these invasive grasses over the native species generally are lacking. In this study, we used experimental data collected in south-central North Dakota, USA to address this issue. Photosynthetic potential was obtained from the net assimilation (A) vs. internal CO 2 (Ci) response curves from plants grown in a greenhouse. Plant success was defined as the average frequency measured over 25 years (1988 to 2012) on overflow range sites across fivemore » levels of grazing intensity. In addition, estimated leaf area index of individual species under field conditions was used to indicate plant success. The correlation between photosynthetic potential based on A/Ci curves and plant frequency was negative. The correlation between leaf photosynthesis and plant success (defined as leaf area within a unit land area) was also negative, although statistically weak. These results suggest that the two cool-season grasses, Poa pratensis and Bromus inermis, do not rely on superior leaf-level photosynthesis for competitive success. Instead, some other traits, such as early and late-season growth, may be more important for them to gain dominance in the mixed-grass prairie. We propose that the negative photosynthesis-frequency relation as observed in this study results from a strong competition for limited soil nutrients in the mixed-grass prairie. In conclusion, it has implications for the stability and productivity of the grassland under various human disruptions influencing the soil nutrient status.« less

Root plasticity buffers competition among plants: theory meets experimental data.

PubMed

Schiffers, Katja; Tielbörger, Katja; Tietjen, Britta; Jeltsch, Florian

2011-03-01

Morphological plasticity is a striking characteristic of plants in natural communities. In the context of foraging behavior particularly, root plasticity has been documented for numerous species. Root plasticity is known to mitigate competitive interactions by reducing the overlap of the individuals' rhizospheres. But despite its obvious effect on resource acquisition, plasticity has been generally neglected in previous empirical and theoretical studies estimating interaction intensity among plants. In this study, we developed a semi-mechanistic model that addresses this shortcoming by introducing the idea of compensatory growth into the classical-zone-of influence (ZOI) and field-of-neighborhood (FON) approaches. The model parameters describing the belowground plastic sphere of influence (PSI) were parameterized using data from an accompanying field experiment. Measurements of the uptake of a stable nutrient analogue at distinct distances to the neighboring plants showed that the study species responded plastically to belowground competition by avoiding overlap of individuals' rhizospheres. An unexpected finding was that the sphere of influence of the study species Bromus hordeaceus could be best described by a unimodal function of distance to the plant's center and not with a continuously decreasing function as commonly assumed. We employed the parameterized model to investigate the interplay between plasticity and two other important factors determining the intensity of competitive interactions: overall plant density and the distribution of individuals in space. The simulation results confirm that the reduction of competition intensity due to morphological plasticity strongly depends on the spatial structure of the competitive environment. We advocate the use of semi-mechanistic simulations that explicitly consider morphological plasticity to improve our mechanistic understanding of plant interactions.

Archaea and bacteria mediate the effects of native species root loss on fungi during plant invasion

PubMed Central

Mamet, Steven D; Lamb, Eric G; Piper, Candace L; Winsley, Tristrom; Siciliano, Steven D

2017-01-01

Although invasive plants can drive ecosystem change, little is known about the directional nature of belowground interactions between invasive plants, native roots, bacteria, archaea and fungi. We used detailed bioinformatics and a recently developed root assay on soils collected in fescue grassland along a gradient of smooth brome (Bromus inermis Leyss) invasion to examine the links between smooth brome shoot litter and root, archaea, bacteria and fungal communities. We examined (1) aboveground versus belowground influences of smooth brome on soil microbial communities, (2) the importance of direct versus microbe-mediated impacts of plants on soil fungal communities, and (3) the web of roots, shoots, archaea, bacteria and fungi interactions across the A and B soil horizons in invaded and non-invaded sites. Archaea and bacteria influenced fungal composition, but not vice versa, as indicated by redundancy analyses. Co-inertia analyses suggested that bacterial–fungal variance was driven primarily by 12 bacterial operational taxonomic units (OTUs). Brome increased bacterial diversity via smooth brome litter in the A horizon and roots in the B horizon, which then reduced fungal diversity. Archaea increased abundance of several bacterial OTUs, and the key bacterial OTUs mediated changes in the fungi’s response to invasion. Overall, native root diversity loss and bacterial mediation were more important drivers of fungal composition than were the direct effects of increases in smooth brome. Critically, native plant species displacement and root loss appeared to be the most important driver of fungal composition during invasion. This causal web likely gives rise to the plant–fungi feedbacks, which are an essential factor determining plant diversity in invaded grassland ecosystems. PMID:28140393

The role of fire in structuring sagebrush habitats and bird communities

USGS Publications Warehouse

Knick, S.T.; Holmes, A.L.; Miller, R.F.; Saab, Victoria A.; Powell, Hugo D.W.

2005-01-01

Fire is a dominant and highly visible disturbance in sagebrush (Artemisia spp.) ecosystems. In lower elevation, xeric sagebrush communities, the role of fire has changed in recent decades from an infrequent disturbance maintaining a landscape mosaic and facilitating community processes to frequent events that alter sagebrush communities to exotic vegetation, from which restoration is unlikely. Because of cheatgrass invasion, fire-return intervals in these sagebrush ecosystems have decreased from an historical pattern (pre-European settlement) of 30 to >100 yr to 5-15 yr. In other sagebrush communities, primarily higher elevation ecosystems, the lack of fire has allowed transitions to greater dominance by sagebrush, loss of herbaceous understory, and expansion of juniper-pinyon woodlands. Response by birds living in sagebrush habitats to fire was related to the frequency, size, complexity (or patchiness), and severity of the burns. Small-scale fires that left patchy distributions of sagebrush did not influence bird populations. However, large-scale fires that resulted in large grassland expanses and isolated existing sagebrush patches reduced the probability of occupancy by sagebrush-obligate species. Populations of birds also declined in sagebrush ecosystems with increasing dominance by juniper (Juniperus spp.) and pinyon (Pinus spp.) woodlands. Our understanding of the effects of fire on sagebrush habitats and birds in these systems is limited. Almost all studies of fire effects on birds have been opportunistic, correlative, and lacking controls. We recommend using the large number of prescribed burns to develop strong inferences about cause-and-effect relationships. Prescribed burning is complicated and highly contentious, particularly in low-elevation, xeric sagebrush communities. Therefore, we need to use the unique opportunities provided by planned burns to understand the spatial and temporal influence of fire on sagebrush landscapes and birds. In particular

Responses to invasion and invader removal differ between native and exotic plant groups in a coastal dune.

PubMed

Magnoli, Susan M; Kleinhesselink, Andrew R; Cushman, J Hall

2013-12-01

The spread of exotic, invasive species is a global phenomenon that is recognized as a major source of environmental change. Although many studies have addressed the effects of exotic plants on the communities they invade, few have quantified the effects of invader removal on plant communities, or considered the degree to which different plant groups vary in response to invasion and invader removal. We evaluated the effects of an exotic succulent, iceplant (Carpobrotus edulis), on a coastal dune plant community in northern California, as well as the community responses to its removal. To assess possible mechanisms by which iceplant affects other plants, we also evaluated its above- and belowground influences on the germination and growth of a dominant exotic annual grass, Bromus diandrus. We found that iceplant invasion was associated with reduced native plant cover as well as increased cover and density of some exotic plants-especially exotic annual grasses. However, iceplant removal did not necessarily lead to a reversal of these effects: removal increased the cover and density of both native and exotic species. We also found that B. diandrus grown in iceplant patches, or in soil where iceplant had been removed, had poorer germination and growth than B. diandrus grown in soil not influenced by iceplant. This suggests that the influence of iceplant on this dune plant community occurs, at least in part, due to belowground effects, and that these effects remain after iceplant has been removed. Our study demonstrates the importance of considering how exotic invasive plants affect not only native species, but also co-occurring exotic taxa. It also shows that combining observational studies with removal experiments can lead to important insights into the influence of invaders and the mechanisms of their effects.

Relative Performance of Non-Local Cultivars and Local, Wild Populations of Switchgrass (Panicum virgatum) in Competition Experiments.

PubMed

Palik, D J; Snow, A A; Stottlemyer, A L; Miriti, M N; Heaton, E A

2016-01-01

The possibility of increased invasiveness in cultivated varieties of native perennial species is a question of interest in biofuel risk assessment. Competitive success is a key factor in the fitness and invasive potential of perennial plants, and thus the large-scale release of high-yielding biomass cultivars warrants empirical comparisons with local conspecifics in the presence of competitors. We evaluated the performance of non-local cultivars and local wild biotypes of the tallgrass species Panicum virgatum L. (switchgrass) in competition experiments during two growing seasons in Ohio and Iowa. At each location, we measured growth and reproductive traits (plant height, tiller number, flowering time, aboveground biomass, and seed production) of four non-locally sourced cultivars and two locally collected wild biotypes. Plants were grown in common garden experiments under three types of competition, referred to as none, moderate (with Schizachyrium scoparium), and high (with Bromus inermis). In both states, the two "lowland" cultivars grew taller, flowered later, and produced between 2x and 7.5x more biomass and between 3x and 34x more seeds per plant than local wild biotypes, while the other two cultivars were comparable to wild biotypes in these traits. Competition did not affect relative differences among biotypes, with the exception of shoot number, which was more similar among biotypes under high competition. Insights into functional differences between cultivars and wild biotypes are crucial for developing biomass crops while mitigating the potential for invasiveness. Here, two of the four cultivars generally performed better than wild biotypes, indicating that these biotypes may pose more of a risk in terms of their ability to establish vigorous feral populations in new regions outside of their area of origin. Our results support an ongoing assessment of switchgrass cultivars developed for large-scale planting for biofuels.

Novel fine-scale aerial mapping approach quantifies grassland weed cover dynamics and response to management.

PubMed

Malmstrom, Carolyn M; Butterfield, H Scott; Planck, Laura; Long, Christopher W; Eviner, Valerie T

2017-01-01

Invasive weeds threaten the biodiversity and forage productivity of grasslands worldwide. However, management of these weeds is constrained by the practical difficulty of detecting small-scale infestations across large landscapes and by limits in understanding of landscape-scale invasion dynamics, including mechanisms that enable patches to expand, contract, or remain stable. While high-end hyperspectral remote sensing systems can effectively map vegetation cover, these systems are currently too costly and limited in availability for most land managers. We demonstrate application of a more accessible and cost-effective remote sensing approach, based on simple aerial imagery, for quantifying weed cover dynamics over time. In California annual grasslands, the target communities of interest include invasive weedy grasses (Aegilops triuncialis and Elymus caput-medusae) and desirable forage grass species (primarily Avena spp. and Bromus spp.). Detecting invasion of annual grasses into an annual-dominated community is particularly challenging, but we were able to consistently characterize these two communities based on their phenological differences in peak growth and senescence using maximum likelihood supervised classification of imagery acquired twice per year (in mid- and end-of season). This approach permitted us to map weed-dominated cover at a 1-m scale (correctly detecting 93% of weed patches across the landscape) and to evaluate weed cover change over time. We found that weed cover was more pervasive and persistent in management units that had no significant grazing for several years than in those that were grazed, whereas forage cover was more abundant and stable in the grazed units. This application demonstrates the power of this method for assessing fine-scale vegetation transitions across heterogeneous landscapes. It thus provides means for small-scale early detection of invasive species and for testing fundamental questions about landscape dynamics.

Mixed artificial grasslands with more roots improved mine soil infiltration capacity

NASA Astrophysics Data System (ADS)

Wu, Gao-Lin; Yang, Zheng; Cui, Zeng; Liu, Yu; Fang, Nu-Fang; Shi, Zhi-Hua

2016-04-01

Soil water is one of the critical limiting factors in achieving sustainable revegetation. Soil infiltration capacity plays a vital role in determining the inputs from precipitation and enhancing water storage, which are important for the maintenance and survival of vegetation patches in arid and semi-arid areas. Our study investigated the effects of different artificial grasslands on soil physical properties and soil infiltration capacity. The artificial grasslands were Medicago sativa, Astragalus adsurgens, Agropyron mongolicum, Lespedeza davurica, Bromus inermis, Hedysarum scoparium, A. mongolicum + Artemisia desertorum, A. adsurgens + A. desertorum and M. sativa + B. inermis. The soil infiltration capacity index (SICI), which was based on the average infiltration rate of stage I (AIRSI) and the average infiltration rate of stage III (AIRS III), was higher (indicating that the infiltration capacity was greater) under the artificial grasslands than that of the bare soil. The SICI of the A. adsurgens + A. desertorum grassland had the highest value (1.48) and bare soil (-0.59) had the lowest value. It was evident that artificial grassland could improve soil infiltration capacity. We also used principal component analysis (PCA) to determine that the main factors that affected SICI were the soil water content at a depth of 20 cm (SWC20), the below-ground root biomasses at depths of 10 and 30 cm (BGB10, BGB30), the capillary porosity at a depth of 10 cm (CP10) and the non-capillary porosity at a depth of 20 cm (NCP20). Our study suggests that the use of Legume-poaceae mixtures and Legume-shrub mixtures to create grasslands provided an effective ecological restoration approach to improve soil infiltration properties due to their greater root biomasses. Furthermore, soil water content, below-ground root biomass, soil capillary porosity and soil non-capillary porosity were the main factors that affect the soil infiltration capacity.

Managed grassland alters soil N dynamics and N2O emissions in temperate steppe.

PubMed

Xu, Lijun; Xu, Xingliang; Tang, Xuejuan; Xin, Xiaoping; Ye, Liming; Yang, Guixia; Tang, Huajun; Lv, Shijie; Xu, Dawei; Zhang, Zhao

2018-04-01

Reclamation of degraded grasslands as managed grasslands has been increasingly accelerated in recent years in China. Land use change affects soil nitrogen (N) dynamics and nitrous oxide (N 2 O) emissions. However, it remains unclear how large-scale grassland reclamation will impact the grassland ecosystem as a whole. Here, we investigated the effects of the conversion from native to managed grasslands on soil N dynamics and N2O emissions by field experiments in Hulunber in northern China. Soil (0-10cm), nitrate (NO 3 - ), ammonium (NH 4 + ), and microbial N were measured in plots in a temperate steppe (Leymus chinensis grassland) and two managed grasslands (Medicago sativa and Bromus inermis grasslands) in 2011 and 2012. The results showed conversion of L. chinensis grassland to M. sativa or B. inermis grasslands decreased concentrations of NO 3 - -N, but did not change NH 4 + -N. Soil microbial N was slightly decreased by the conversion of L. chinensis grassland to M. sativa, but increased by the conversion to B. inermis. The conversion of L. chinensis grassland to M. sativa (i.e., a legume grass) increased N 2 O emissions by 26.2%, while the conversion to the B. inermis (i.e., a non-legume grass) reduced N 2 O emissions by 33.1%. The conversion from native to managed grasslands caused large created variations in soil NO 3 - -N and NH 4 + -N concentrations. Net N mineralization rates did not change significantly in growing season or vegetation type, but to net nitrification rate. These results provide evidence on how reclamation may impact the grassland ecosystem in terms of N dynamics and N 2 O emissions. Copyright © 2017. Published by Elsevier B.V.

Germination sensitivities to water potential among co-existing C3 and C4 grasses of cool semi-arid prairie grasslands.

PubMed

Mollard, F P O; Naeth, M A

2015-03-01

An untested theory states that C4 grass seeds could germinate under lower water potentials (Ψ) than C3 grass seeds. We used hydrotime modelling to study seed water relations of C4 and C3 Canadian prairie grasses to address Ψ divergent sensitivities and germination strategies along a risk-spreading continuum of responses to limited water. C4 grasses were Bouteloua gracilis, Calamovilfa longifolia and Schizachyrium scoparium; C3 grasses were Bromus carinatus, Elymus trachycaulus, Festuca hallii and Koeleria macrantha. Hydrotime parameters were obtained after incubation of non-dormant seeds under different Ψ PEG 6000 solutions. A t-test between C3 and C4 grasses did not find statistical differences in population mean base Ψ (Ψb (50)). We found idiosyncratic responses of C4 grasses along the risk-spreading continuum. B. gracilis showed a risk-taker strategy of a species able to quickly germinate in a dry soil due to its low Ψb (50) and hydrotime (θH ). The high Ψb (50) of S. scoparium indicates it follows the risk-averse strategy so it can only germinate in wet soils. C. longifolia showed an intermediate strategy: the lowest Ψb (50) yet the highest θH . K. macrantha, a C3 grass which thrives in dry habitats, had the highest Ψb (50), suggesting a risk-averse strategy for a C3 species. Other C3 species showed intermediate germination patterns in response to Ψ relative to C4 species. Our results indicate that grasses display germination sensitivities to Ψ across the risk-spreading continuum of responses. Thus seed water relations may be poor predictors to explain differential recruitment and distribution of C3 and C4 grasses in the Canadian prairies. © 2014 German Botanical Society and The Royal Botanical Society of the Netherlands.

An emerging crisis across northern prairie refuges: Prevalence of invasive plants and a plan for adaptive management

USGS Publications Warehouse

Grant, T.A.; Flanders-Wanner, B.; Shaffer, T.L.; Murphy, R.K.; Knutsen, G.A.

2009-01-01

In the northern Great Plains, native prairies managed by the U.S. Fish and Wildlife Service (Service) can be pivotal in conservation of North America's biological diversity. From 2002 to 2006, we surveyed 7,338 belt transects to assess the general composition of mixed-grass and tallgrass prairie vegetation across five "complexes" (i.e., administrative groupings) of national wildlife refuges managed by the Service in North Dakota and South Dakota. Native grasses and forbs were common (mean frequency of occurrence 47%-54%) on two complexes but uncommon (4%-13%) on two others. Conversely, an introduced species of grass, smooth brome (Bromus inermis), accounted for 45% to 49% of vegetation on two complexes and another species, Kentucky bluegrass (Poa pratensis) accounted for 27% to 36% of the vegetation on three of the complexes. Our data confirm prior suspicions of widespread invasion by introduced species of plants on Service-owned tracts of native prairie, changes that likely stem in part from a common management history of little or no disturbance (e.g., defoliation by grazing or fire). However, variability in the degree and type of invasion among prairie tracts suggests that knowledge of underlying causes (e.g., edaphic or climatic factors, management histories) could help managers more effectively restore prairies. We describe an adaptive management approach to acquire such knowledge while progressing with restoration. More specifically, we propose to use data from inventories of plant communities on Service-owned prairies to design and implement, as experiments, optimal restoration strategies. We will then monitor these experiments and use the results to refine future strategies. This comprehensive, process-oriented approach should yield reliable and robust recommendations for restoration and maintenance of native prairies in the northern Great Plains. 2009 by the Board of Regents of the University of Wisconsin System.

The effect of nitrogen availability and water conditions on competition between a facultative CAM plant and an invasive grass.

PubMed

Yu, Kailiang; D'Odorico, Paolo; Carr, David E; Personius, Ashden; Collins, Scott L

2017-10-01

Plants with crassulacean acid metabolism (CAM) are increasing their abundance in drylands worldwide. The drivers and mechanisms underlying the increased dominance of CAM plants and CAM expression (i.e., nocturnal carboxylation) in facultative CAM plants, however, remain poorly understood. We investigated how nutrient and water availability affected competition between Mesembryanthemum crystallinum (a model facultative CAM species) and the invasive C 3 grass Bromus mollis that co-occur in California's coastal grasslands. Specifically we investigated the extent to which water stress, nutrients, and competition affect nocturnal carboxylation in M. crystallinum . High nutrient and low water conditions favored M. crystallinum over B. mollis , in contrast to high water conditions. While low water conditions induced nocturnal carboxylation in 9-week-old individuals of M. crystallinum , in these low water treatments, a 66% reduction in nutrient applied over the entire experiment did not further enhance nocturnal carboxylation. In high water conditions M. crystallinum both alone and in association with B. mollis did not perform nocturnal carboxylation, regardless of the nutrient levels. Thus, nocturnal carboxylation in M. crystallinum was restricted by strong competition with B. mollis in high water conditions. This study provides empirical evidence of the competitive advantage of facultative CAM plants over grasses in drought conditions and of the restricted ability of M. crystallinum to use their photosynthetic plasticity (i.e., ability to switch to CAM behavior) to compete with grasses in well-watered conditions. We suggest that a high drought tolerance could explain the increased dominance of facultative CAM plants in a future environment with increased drought and nitrogen deposition, while the potential of facultative CAM plants such as M. crystallinum to expand to wet environments is expected to be limited.

Perennial filter strips reduce nitrate levels in soil and shallow groundwater after grassland-to-cropland conversion.

PubMed

Zhou, Xiaobo; Helmers, Matthew J; Asbjornsen, Heidi; Kolka, Randy; Tomer, Mark D

2010-01-01

Many croplands planted to perennial grasses under the Conservation Reserve Program are being returned to crop production, and with potential consequences for water quality. The objective of this study was to quantify the impact of grassland-to-cropland conversion on nitrate-nitrogen (NO3-N) concentrations in soil and shallow groundwater and to assess the potential for perennial filter strips (PFS) to mitigate increases in NO3-N levels. The study, conducted at the Neal Smith National Wildlife Refuge (NSNWR) in central Iowa, consisted of a balanced incomplete block design with 12 watersheds and four watershed-scale treatments having different proportions and topographic positions of PFS planted in native prairie grasses: 100% rowcrop, 10% PFS (toeslope position), 10% PFS (distributed on toe and as contour strips), and 20 PFS (distributed on toe and as contour strips). All treatments were established in fall 2006 on watersheds that were under bromegrass (Bromus L.) cover for at least 10 yr. Nonperennial areas were maintained under a no-till 2-yr corn (Zea mays L.)--soybean [Glycine max. (L.) Merr.] rotation since spring 2007. Suction lysimeter and shallow groundwater wells located at upslope and toeslope positions were sampled monthly during the growing season to determine NO3-N concentration from 2005 to 2008. The results indicated significant increases in NO3-N concentration in soil and groundwater following grassland-to-cropland conversion. Nitrate-nitrogen levels in the vadose zone and groundwater under PFS were lower compared with 100% cropland, with the most significant differences occurring at the toeslope position. During the years following conversion, PFS mitigated increases in subsurface nitrate, but long-term monitoring is needed to observe and understand the full response to land-use conversion.

Relative Performance of Non-Local Cultivars and Local, Wild Populations of Switchgrass (Panicum virgatum) in Competition Experiments

PubMed Central

Palik, D. J.; Snow, A. A.; Stottlemyer, A. L.; Miriti, M. N.; Heaton, E. A.

2016-01-01

The possibility of increased invasiveness in cultivated varieties of native perennial species is a question of interest in biofuel risk assessment. Competitive success is a key factor in the fitness and invasive potential of perennial plants, and thus the large-scale release of high-yielding biomass cultivars warrants empirical comparisons with local conspecifics in the presence of competitors. We evaluated the performance of non-local cultivars and local wild biotypes of the tallgrass species Panicum virgatum L. (switchgrass) in competition experiments during two growing seasons in Ohio and Iowa. At each location, we measured growth and reproductive traits (plant height, tiller number, flowering time, aboveground biomass, and seed production) of four non-locally sourced cultivars and two locally collected wild biotypes. Plants were grown in common garden experiments under three types of competition, referred to as none, moderate (with Schizachyrium scoparium), and high (with Bromus inermis). In both states, the two “lowland” cultivars grew taller, flowered later, and produced between 2x and 7.5x more biomass and between 3x and 34x more seeds per plant than local wild biotypes, while the other two cultivars were comparable to wild biotypes in these traits. Competition did not affect relative differences among biotypes, with the exception of shoot number, which was more similar among biotypes under high competition. Insights into functional differences between cultivars and wild biotypes are crucial for developing biomass crops while mitigating the potential for invasiveness. Here, two of the four cultivars generally performed better than wild biotypes, indicating that these biotypes may pose more of a risk in terms of their ability to establish vigorous feral populations in new regions outside of their area of origin. Our results support an ongoing assessment of switchgrass cultivars developed for large-scale planting for biofuels. PMID:27120201

Novel fine-scale aerial mapping approach quantifies grassland weed cover dynamics and response to management

PubMed Central

Butterfield, H. Scott; Planck, Laura; Long, Christopher W.; Eviner, Valerie T.

2017-01-01

Invasive weeds threaten the biodiversity and forage productivity of grasslands worldwide. However, management of these weeds is constrained by the practical difficulty of detecting small-scale infestations across large landscapes and by limits in understanding of landscape-scale invasion dynamics, including mechanisms that enable patches to expand, contract, or remain stable. While high-end hyperspectral remote sensing systems can effectively map vegetation cover, these systems are currently too costly and limited in availability for most land managers. We demonstrate application of a more accessible and cost-effective remote sensing approach, based on simple aerial imagery, for quantifying weed cover dynamics over time. In California annual grasslands, the target communities of interest include invasive weedy grasses (Aegilops triuncialis and Elymus caput-medusae) and desirable forage grass species (primarily Avena spp. and Bromus spp.). Detecting invasion of annual grasses into an annual-dominated community is particularly challenging, but we were able to consistently characterize these two communities based on their phenological differences in peak growth and senescence using maximum likelihood supervised classification of imagery acquired twice per year (in mid- and end-of season). This approach permitted us to map weed-dominated cover at a 1-m scale (correctly detecting 93% of weed patches across the landscape) and to evaluate weed cover change over time. We found that weed cover was more pervasive and persistent in management units that had no significant grazing for several years than in those that were grazed, whereas forage cover was more abundant and stable in the grazed units. This application demonstrates the power of this method for assessing fine-scale vegetation transitions across heterogeneous landscapes. It thus provides means for small-scale early detection of invasive species and for testing fundamental questions about landscape dynamics. PMID

Removal of antibiotics and antibiotic resistance genes from domestic sewage by constructed wetlands: Effect of flow configuration and plant species.

PubMed

Chen, Jun; Ying, Guang-Guo; Wei, Xiao-Dong; Liu, You-Sheng; Liu, Shuang-Shuang; Hu, Li-Xin; He, Liang-Ying; Chen, Zhi-Feng; Chen, Fan-Rong; Yang, Yong-Qiang

2016-11-15

This study aims to investigate the removal of antibiotics and antibiotic resistance genes (ARGs) in raw domestic wastewater by various mesocosm-scale constructed wetlands (CWs) with different flow configurations or plant species including the constructed wetland with or without plant. Six mesocosm-scale CWs with three flow types (surface flow, horizontal subsurface flow and vertical subsurface flow) and two plant species (Thaliadealbata Fraser and Iris tectorum Maxim) were set up in the outdoor. 8 antibiotics including erythromycin-H2O (ETM-H2O), monensin (MON), clarithromycin (CTM), leucomycin (LCM), sulfamethoxazole (SMX), trimethoprim (TMP), sulfamethazine (SMZ) and sulfapyridine (SPD) and 12 genes including three sulfonamide resistance genes (sul1, sul2 and sul3), four tetracycline resistance genes (tetG, tetM, tetO and tetX), two macrolide resistance genes (ermB and ermC), two chloramphenicol resistance genes (cmlA and floR) and 16S rRNA (bacteria) were determined in different matrices (water, particle, substrate and plant phases) from the mesocosm-scale systems. The aqueous removal efficiencies of total antibiotics ranged from 75.8 to 98.6%, while those of total ARGs varied between 63.9 and 84.0% by the mesocosm-scale CWs. The presence of plants was beneficial to the removal of pollutants, and the subsurface flow CWs had higher pollutant removal than the surface flow CWs, especially for antibiotics. According to the mass balance analysis, the masses of all detected antibiotics during the operation period were 247,000, 4920-10,600, 0.05-0.41 and 3500-60,000μg in influent, substrate, plant and effluent of the mesocosm-scale CWs. In the CWs, biodegradation, substrate adsorption and plant uptake all played certain roles in reducing the loadings of nutrients, antibiotics and ARGs, but biodegradation was the most important process in the removal of these pollutants. Copyright © 2016 Elsevier B.V. All rights reserved.

Hydrologic Impacts Associated with the Increased Role of Wildland Fire Across the Rangeland-Xeric Forest Continuum of the Great Basin and Intermountain West, USA

NASA Astrophysics Data System (ADS)

Williams, C. J.; Pierson, F. B.; Robichaud, P. R.; Boll, J.; Al-Hamdan, O. Z.

2011-12-01

The increased role of wildland fire across the rangeland-xeric forest continuum in the western United States (US) presents landscape-scale consequences relative runoff and erosion. Concomitant climate conditions and altered plant community transitions in recent decades along grassland-shrubland-woodland-xeric forest transitions have promoted frequent and large wildland fires, and the continuance of the trend appears likely if current or warming climate conditions prevail. Much of the Great Basin and Intermountain West in the US now exists in a state in which rangeland and woodland wildfires stimulated by invasive cheatgrass and dense, horizontal and vertical fuel layers have a greater likelihood of progressing upslope into xeric forests. Drier moisture conditions and warmer seasonal air temperatures, along with dense fuel loads, have lengthened fire seasons and facilitated an increase in the frequency, severity and area burned in mid-elevation western US forests. These changes potentially increase the overall hydrologic vulnerability across the rangeland-xeric forest continuum by spatially and temporally increasing soil surface exposure to runoff and erosion processes. Plot-to-hillslope scale studies demonstrate burning may increase event runoff and/or erosion by factors of 2-40 over small-plots scales and more than 100-fold over large-plot to hillslope scales. Anecdotal reports of large-scale flooding and debris-flow events from rangelands and xeric forests following burning document the potential risk to resources (soil loss, water quality, degraded aquatic habitat, etc.), property and infrastructure, and human life. Such risks are particularly concerning for urban centers near the urban-wildland interface. We do not yet know the long-term ramifications of frequent soil loss associated with commonly occurring runoff events on repeatedly burned sites. However, plot to landscape-scale post-fire erosion rate estimates suggest potential losses of biologically

PLUTONIUM UPTAKE AND BEHAVIOR IN PLANTS OF THE DESERT SOUTHWEST: A PRELIMINARY ASSESSMENT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Caldwell, E.; Duff, M.; Ferguson, C.

2011-03-01

Eight species of desert vegetation and associated soils were collected from the Nevada National Security Site (N2S2) and analyzed for 238Pu and 239+240Pu concentrations. Amongst the plant species sampled were: atmospheric elemental accumulators (moss and lichen), the very slow growing, long-lived creosote bush and the rapidly growing, short-lived cheatgrass brome. The diversity of growth strategies provided insight into the geochemical behavior and bio-availability of Pu at the N2S2. The highest concentrations of Pu were measured in the onion moss (24.27 Bq kg-1 238Pu and 52.78 Bq kg-1 239+240Pu) followed by the rimmed navel lichen (8.18 Bq kg-1 and 18.4 Bqmore » kg-1 respectively), pointing to the importance of eolian transport of Pu. Brome and desert globemallow accumulated between 3 and 9 times higher concentrations of Pu than creosote and sage brush species. These results support the importance of species specific elemental accumulation strategies rather than exposure duration as the dominant variable influencing Pu concentrations in these plants. Total vegetation elemental concentrations of Ce, Fe, Al, Sm and others were also analyzed. Strong correlations were observed between Fe and Pu. This supports the conclusion that Pu was accumulated as a consequence of the active accumulation of Fe and other plant required nutrients. Cerium and Pu are considered to be chemical analogs. Strong correlations observed in plants support the conclusion that these elements displayed similar geochemical behavior in the environment as it related to the biochemical uptake process of vegetation. Soils were also sampled in association with vegetation samples. This allowed for the calculation of a concentration ratio (CR). The CR values for Pu in plants were highly influenced by the heterogeneity of Pu distribution among sites. Results from the naturally occurring elements of concern were more evenly distributed between sample sites. This allowed for the development of a pattern

Quantifying restoration effectiveness using multi-scale habitat models: implications for sage-grouse in the Great Basin

USGS Publications Warehouse

Arkle, Robert S.; Pilliod, David S.; Hanser, Steven E.; Brooks, Matthew L.; Chambers, Jeanne C.; Grace, James B.; Knutson, Kevin C.; Pyke, David A.; Welty, Justin L.

2014-01-01

conditions, but in most climates, establishing forbs and reducing cheatgrass dominance is unlikely. Reestablishing sagebrush cover will require more than 20 years using past restoration methods. Given current fire frequencies and restoration capabilities, protection of landscapes containing a mix of dwarf sagebrush and big sagebrush steppe, minimal human development, and low non-native plant cover may provide the best opportunity for conservation of sage-grouse habitats.

Growth and fecundity of fertile Miscanthus × giganteus ("PowerCane") compared to feral and ornamental Miscanthus sinensis in a common garden experiment: Implications for invasion.

PubMed

Miriti, Maria N; Ibrahim, Tahir; Palik, Destiny; Bonin, Catherine; Heaton, Emily; Mutegi, Evans; Snow, Allison A

2017-08-01

Perennial grasses are promising candidates for bioenergy crops, but species that can escape cultivation and establish self-sustaining naturalized populations (feral) may have the potential to become invasive. Fertile Miscanthus  ×  giganteus , known as "PowerCane," is a new potential biofuel crop. Its parent species are ornamental, non-native Miscanthus species that establish feral populations and are sometimes invasive in the USA. As a first step toward assessing the potential for "PowerCane" to become invasive, we documented its growth and fecundity relative to one of its parent species ( Miscanthus sinensis ) in competition with native and invasive grasses in common garden experiments located in Columbus, Ohio and Ames, Iowa, within the targeted range of biofuel cultivation. We conducted a 2-year experiment to compare growth and reproduction among three Miscanthus biotypes-"PowerCane," ornamental M. sinensis , and feral M. sinensis -at two locations. Single Miscanthus plants were subjected to competition with a native grass ( Panicum virgatum ), a weedy grass ( Bromus inermis ), or no competition. Response variables were aboveground biomass, number of shoots, basal area, and seed set. In Iowa, all Miscanthus plants died after the first winter, which was unusually cold, so no further results are reported from the Iowa site. In Ohio, we found significant differences among biotypes in growth and fecundity, as well as significant effects of competition. Interactions between these treatments were not significant. "PowerCane" performed as well or better than ornamental or feral M. sinensis in vegetative traits, but had much lower seed production, perhaps due to pollen limitation. In general, ornamental M. sinensis performed somewhat better than feral M. sinensis . Our findings suggest that feral populations of "PowerCane" could become established adjacent to biofuel production areas. Fertile Miscanthus  ×  giganteus should be studied further to assess its

Contrasted nitrogen utilization in annual C 3 grass and legume crops: Physiological explorations and ecological considerations

NASA Astrophysics Data System (ADS)

Del Pozo, Alejandro; Garnier, Eric; Aronson, James

2000-01-01

Although it is well known that legumes have unusually high levels of nitrogen in both reproductive and vegetative organs, the physiological implications of this pattern have been poorly assessed. We conducted a literature survey and used data from two (unpublished) experiments on annual legumes and C 3 grasses in order to test whether these high nitrogen concentrations in legumes are correlated to high rates of carbon gain. Three different temporal/spatial scales were considered: full growing season/stand, days to month/whole plant and seconds/leaf. At the stand level, and for plants grown under both extratropical and tropical settings, biomass per unit organic-nitrogen was lower in legume than in grass crops. At a shorter time scale, the relative growth rate per unit plant nitrogen (`nitrogen productivity') was lower in faba bean ( Vicia faba var. minor cv. Tina) than in wheat ( Triticum aestivum cv. Alexandria), and this was confirmed in a comparison of two wild, circum-Mediterranean annuals - Medicago minima, a legume, and Bromus madritensis, a grass. Finally, at the leaf level, a synthesis of published data comparing soybean ( Glycine max) and rice ( Oryza sativa) on the one hand, and our own data on faba bean and wheat on the other hand, demonstrates that the photosynthetic rate per unit leaf nitrogen (the photosynthetic nitrogen use efficiency) is consistently lower in legumes than in grasses. These results demonstrate that, regardless of the scale considered and although the organic-nitrogen concentration in vegetative organs of legumes is higher than in grasses, this does not lead to higher rates of carbon gain in the former. Various physiological factors affecting the efficiency of nitrogen utilization at the three time scales considered are discussed. The suggestion is made that the ecological significance of the high nitrogen concentration in legumes may be related to a high nitrogen demand for high quality seed production at a time when nitrogen

CO2 EFFECTS ON MOJAVE DESERT PLANT INTERACTIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

L. A. DEFALCO; G. C. FERNANDEZ; S. D. SMITH

2004-01-01

Seasonal and interannual droughts characteristic of deserts have the potential to modify plant interactions as atmospheric CO{sub 2} concentrations continue to rise. At the Nevada Desert FACE (free-air CO{sub 2} enrichment) facility in the northern Mojave Desert, the effects of elevated atmospheric C02 (550 vs. ambient {approx}360 {micro}mol mol{sup -1}) on plant interactions were examined during two years of high and low rainfall. Results suggest that CO{sub 2} effects on the interaction between native species and their understory herbs are dependent on the strength of competition when rainfall is plentiful, but are unimportant during annual drought. Seasonal rainfall for 1999more » was 23% the long-term average for the area, and neither elevated CO{sub 2} nor the low production of herbaceous neighbors had an effect on relative growth rate (RGR, d{sup -1}) and reproductive effort (RE, number of flowers g{sup -1}) for Achnatherum hymenoides (early season perennial C{sub 3} grass), Pleuraphis rigida (late season perennial C{sub 4} grass), and Larrea tridentata (evergreen C{sub 3} shrub). In contrast, 1998 received 213% the average rainfall. Consequently, the decrease in RGR and increase in RE for Achnatherum, whose period of growth overlaps directly with that of its neighbors, was exaggerated at elevated CO{sub 2}. However, competitive effects of neighbors on Eriogonum trichopes (a winter annual growing in shrub interspaces), Pleuraphis and Larrea were not affected by elevated CO{sub 2}, and possible explanations are discussed. Contrary to expectations, the invasive annual neighbor Bromus madritensis ssp. rubens had little influence on target plant responses because densities in 1998 and 1999 at this site were well below those found in other studies where it has negatively affected perennial plant growth. The extent that elevated CO{sub 2} reduces the performance of Achnatherum in successive years to cause its loss from the plant community depends more on future

The carbon fertilization effect over a century of anthropogenic CO2 emissions: higher intracellular CO2 and more drought resistance among invasive and native grass species contrasts with increased water use efficiency for woody plants in the US Southwest.

PubMed

Drake, Brandon L; Hanson, David T; Lowrey, Timothy K; Sharp, Zachary D

2017-02-01

From 1890 to 2015, anthropogenic carbon dioxide emissions have increased atmospheric CO 2 concentrations from 270 to 400 mol mol -1 . The effect of increased carbon emissions on plant growth and reproduction has been the subject of study of free-air CO 2 enrichment (FACE) experiments. These experiments have found (i) an increase in internal CO 2 partial pressure (c i ) alongside acclimation of photosynthetic capacity, (ii) variable decreases in stomatal conductance, and (iii) that increases in yield do not increase commensurate with CO 2 concentrations. Our data set, which includes a 115-year-long selection of grasses collected in New Mexico since 1892, is consistent with an increased c i as a response to historical CO 2 increase in the atmosphere, with invasive species showing the largest increase. Comparison with Palmer Drought Sensitivity Index (PDSI) for New Mexico indicates a moderate correlation with Δ 13 C (r 2  = 0.32, P < 0.01) before 1950, with no correlation (r 2  = 0.00, P = 0.91) after 1950. These results indicate that increased c i may have conferred some drought resistance to these grasses through increased availability of CO 2 in the event of reduced stomatal conductance in response to short-term water shortage. Comparison with C 3 trees from arid environments (Pinus longaeva and Pinus edulis in the US Southwest) as well as from wetter environments (Bromus and Poa grasses in New Mexico) suggests differing responses based on environment; arid environments in New Mexico see increased intrinsic water use efficiency (WUE) in response to historic elevated CO 2 while wetter environments see increased c i . This study suggests that (i) the observed increases in c i in FACE experiments are consistent with historical CO 2 increases and (ii) the CO 2 increase influences plant sensitivity to water shortage, through either increased WUE or c i in arid and wet environments, respectively. © 2016 John Wiley & Sons Ltd.

Assessing the biophysical naturalness of grassland in eastern North Dakota with hyperspectral imagery

NASA Astrophysics Data System (ADS)

Zhou, Qiang

Over the past two decades, non-native species within grassland communities have quickly developed due to human migration and commerce. Invasive species like Smooth Brome grass (Bromus inermis) and Kentucky Blue Grass (Poa pratensis), seriously threaten conservation of native grasslands. This study aims to discriminate between native grasslands and planted hayfields and conservation areas dominated by introduced grasses using hyperspectral imagery. Hyperspectral imageries from the Hyperion sensor on EO-1 were acquired in late spring and late summer on 2009 and 2010. Field spectra for widely distributed species as well as smooth brome grass and Kentucky blue grass were collected from the study sites throughout the growing season. Imagery was processed with an unmixing algorithm to estimate fractional cover of green and dry vegetation and bare soil. As the spectrum is significantly different through growing season, spectral libraries for the most common species are then built for both the early growing season and late growing season. After testing multiple methods, the Adaptive Coherence Estimator (ACE) was used for spectral matching analysis between the imagery and spectral libraries. Due in part to spectral similarity among key species, the results of spectral matching analysis were not definitive. Additional indexes, "Level of Dominance" and "Band variance", were calculated to measure the predominance of spectral signatures in any area. A Texture co-occurrence analysis was also performed on both "Level of Dominance" and "Band variance" indexes to extract spatial characteristics. The results suggest that compared with disturbed area, native prairie tend to have generally lower "Level of Dominance" and "Band variance" as well as lower spatial dissimilarity. A final decision tree model was created to predict presence of native or introduced grassland. The model was more effective for identification of Mixed Native Grassland than for grassland dominated by a single

Simple sequence repeat markers that identify Claviceps species and strains.

PubMed

Gilmore, Barbara S; Alderman, Stephen C; Knaus, Brian J; Bassil, Nahla V; Martin, Ruth C; Dombrowski, James E; Dung, Jeremiah K S

2016-01-01

Claviceps purpurea is a pathogen that infects most members of Pooideae, a subfamily of Poaceae, and causes ergot, a floral disease in which the ovary is replaced with a sclerotium. When the ergot body is accidently consumed by either man or animal in high enough quantities, there is extreme pain, limb loss and sometimes death. This study was initiated to develop simple sequence repeat (SSRs) markers for rapid identification of  C. purpurea . SSRs were designed from sequence data stored at the National Center for Biotechnology Information database. The study consisted of 74 ergot isolates, from four different host species, Lolium perenne , Poa pratensis , Bromus inermis , and Secale cereale plus three additional Claviceps species, C. pusilla , C. paspali and C. fusiformis. Samples were collected from six different counties in Oregon and Washington over a 5-year period. Thirty-four SSR markers were selected, which enabled the differentiation of each isolate from one another based solely on their molecular fingerprints. Discriminant analysis of principle components was used to identify four isolate groups, CA Group 1, 2, 3, and 4, for subsequent cluster and molecular variance analyses. CA Group 1 consisting of eight isolates from the host species P. pratensis , was separated on the cluster analysis plot from the remaining three groups and this group was later identified as C. humidiphila . The other three groups were distinct from one another, but closely related. These three groups contained samples from all four of the host species. These SSRs are simple to use, reliable and allowed clear differentiation of C. humidiphila from C. purpurea . Isolates from the three separate species, C. pusilla , C. paspali and C. fusiformis , also amplified with these markers. The SSR markers developed in this study will be helpful in defining the population structure and genetics of Claviceps strains. They will also provide valuable tools for plant breeders needing to identify

DOE Office of Scientific and Technical Information (OSTI.GOV)

David C. Anderson, Lloyd T. Desotell, David B. Hudson, Gregory J. Shott, Vefa Yucel

Since January 2001, drainage lysimeter studies have been conducted at Yucca Flat, on the Nevada Test Site, in support of an evapotranspirative cover design. Yucca Flat has an arid climate with average precipitation of 16.5 cm annually. The facility consists of six drainage lysimeters 3 m in diameter, 2.4 m deep, and backfilled with a single layer of native soil. The bottom of each lysimeter is sealed and equipped with a small drain that enables direct measurement of saturated drainage. Each lysimeter has eight time-domain reflectometer probes to measure moisture content-depth profiles paired with eight heat-dissipation probes to measure soil-watermore » potential depth profiles. Sensors are connected to dataloggers which are remotely accessed via a phone line. The six lysimeters have three different surface treatments: two are bare-soil; two were revegetated with native species (primarily shadscale, winterfat, ephedra, and Indian rice grass); and two were allowed to revegetate naturally with such species as Russian thistle, halogeton, tumblemustard and cheatgrass. Beginning in October 2003, one half of the paired cover treatments (one bare soil, one invader species, and one native species) were irrigated with an amount of water equal to two times the natural precipitation to achieve a three times natural precipitation treatment. From October 2003 through December 2005, all lysimeters received 52.8 cm precipitation, and the four irrigated lysimeters received an extra 105.6 cm of irrigation. No drainage has occurred from any of the nonirrigated lysimeters, but moisture has accumulated at the bottom of the bare-soil lysimeter and the native-plant lysimeter. All irrigated lysimeters had some drainage. The irrigated baresoil lysimeter had 48.3 cm of drainage or 26.4 percent of the combined precipitation and applied irrigation for the entire monitoring record. The irrigated invader species lysimeter had 5.8 cm of drainage, about 3.2 percent of the combined

Contrasting patterns of groundwater evapotranspiration in grass and tree dominated riparian zones of a temperate agricultural catchment

NASA Astrophysics Data System (ADS)

Satchithanantham, Sanjayan; Wilson, Henry F.; Glenn, Aaron J.

2017-06-01

Consumptive use of shallow groundwater by phreatophytic vegetation is a significant part of the water budget in many regions, particularly in riparian areas. The influence of vegetation type on groundwater level fluctuations and evapotranspiration has rarely been quantified for contrasting plant communities concurrently although it has implications for downstream water yield and quality. Hourly groundwater evapotranspiration (ETG) rates were estimated for grass and tree riparian vegetation in southwestern Manitoba, Canada using two modified White methods. Groundwater table depth was monitored in four 21 m transects of five 3 m deep monitoring wells in the riparian zone of a stream reach including tree (Acer negundo; boxelder) and grass (Bromus inermis; smooth brome) dominated segments. The average depths to the groundwater table from the surface were 1.4 m and 1 m for the tree and grass segments, respectively, over the two-year study. During rain free periods of the growing season ETG was estimated for a total of 70 days in 2014 and 79 days in 2015 when diurnal fluctuations were present in groundwater level. Diurnal groundwater level fluctuations were observed during dry periods under both segments, however, ETG was significantly higher (p < 0.001) under trees compared to grass cover in 2014 (a wet year with 72% higher than normal growing season precipitation) and 2015 (a drier year with 15% higher than normal growing season precipitation). The two methods used to estimate ETG produced similar daily and seasonal values for the two segments. In 2014, total ETG was approximately 50% (148 mm) and 100% (282-285 mm) of reference evapotranspiration (ETref, 281 mm) for the grass and tree segments, respectively. In 2015, total ETG was approximately 40% (106-127 mm) and 120% (369-374 mm) of ETref (307 mm) for the grass and tree segments, respectively. Results from the study show the tree dominated portions of the stream reach consumed approximately 2.4 ML ha-1 yr-1 more

Spreaders, igniters, and burning shrubs: plant flammability explains novel fire dynamics in grass-invaded deserts.

PubMed

Fuentes-Ramirez, Andres; Veldman, Joseph W; Holzapfel, Claus; Moloney, Kirk A

2016-10-01

Novel fire regimes are an important cause and consequence of global environmental change that involve interactions among biotic, climatic, and human components of ecosystems. Plant flammability is key to these interactions, yet few studies directly measure flammability or consider how multiple species with different flammabilities interact to produce novel fire regimes. Deserts of the southwestern United States are an ideal system for exploring how novel fire regimes can emerge when fire-promoting species invade ecosystems comprised of species that did not evolve with fire. In these deserts, exotic annual grasses provide fuel continuity across landscapes that did not historically burn. These fires often ignite a keystone desert shrub, the fire-intolerant creosote bush, Larrea tridentata (DC.) Coville. Ignition of Larrea is likely catalyzed by fuels produced by native plants that grow beneath the shrubs. We hypothesize that invasive and native species exhibit distinct flammability characteristics that in combination determine spatial patterns of fire spread and intensity. We measured flammability metrics of Larrea, two invasive grasses, Schismus arabicus and Bromus madritensis, and two native plants, the sub-shrub Ambrosia dumosa and the annual herb Amsinckia menziesii. Results of laboratory experiments show that the grasses carry fire quickly (1.32 cm/s), but burn for short duration (0.5 min) at low temperatures. In contrast, native plants spread fire slowly (0.12 cm/s), but burn up to eight times longer (4 min) and produced hotter fires. Additional experiments on the ignition requirements of Larrea suggest that native plants burn with sufficient temperature and duration to ignite dead Larrea branches (time to ignition, 2 min; temperature at ignition 692°C). Once burning, these dead branches ignite living branches in the upper portions of the shrub. Our study provides support for a conceptual model in which exotic grasses are "spreaders" of fire and native

Expansion of plants with Crassulacean Acid Metabolism under global environment change

NASA Astrophysics Data System (ADS)

Yu, K.; D'Odorico, P.; Collins, S. L.; Carr, D.

2016-12-01

The abundance of plants with Crassulacean Acid Metabolism (CAM) has increased in many drylands worldwide. This is hypothesized to occur because CAM plants store water, take up CO2 at night, exhibit photosynthetic plasticity, and have high water use efficiency. The increased dominance of CAM plants, however, also depends on their competitive relationship with other functional groups, an aspect of CAM plant sensitivity to global environmental change that has remained largely understudied. Here, we investigated the response of CAM plants and their competitive relationships with C3 and C4 plants under global environmental change. We focused on two pairs of CAM and non-CAM species, namely Cylindropuntia imbricata (a constitutive CAM species) and Bouteloua eriopoda (C4 grass), which co-occur in desert grasslands in northern Mexico, and invasive Mesembryanthemum crystallinum (a facultative CAM species) and Bromus mollis (a C3 invasive grass), which coexist in California's coastal grasslands. A set of growth chamber experiments under altered CO2 and water conditions show that C. imbricata outcompeted B. eriopoda under drought conditions, while in well-watered conditions B. eriopoda was a stronger competitor for soil water than C. imbricata. Under drought conditions a more positive response to CO2 enrichment by C. imbricata indirectly disfavored B. eriopoda, which suggests that interspecific competition can outweigh the favorable direct effect of CO2 enrichment on plant growth. A set of greenhouse experiments under water, N, and soil salinity manipulations showed that drought, N deposition, and/or increased soil salinity served as important drivers for success of M. crystallinum invasion, while B. mollis exerted strong competitive effects on M. crystallinum for light and soil nutrients in well-watered conditions. M. crystallinum switched from C3 photosynthesis to CAM photosynthesis as an adaptive strategy in response to moderate intensity of competition from B. mollis, in

Elevated CO(2) and nitrogen effects on a dominant N(2)- fixing shrub

NASA Astrophysics Data System (ADS)

Wallace, Alison Marie

The responses of N2-fixing species to global change are likely to be an important component in predicting the existence and direction of feedbacks between carbon and nitrogen cycles, as both are radically changing at an unprecedented pace. Increased carbon storage may be more likely in ecosystems not limited by available nitrogen, such as those with abundant N2-fixing species. If elevated CO2 affects growth and N2-fixation of dominant N2-fixers, then non-fixers in the system may experience indirect effects through changes in competitive interactions and nitrogen availability. The goal of this research was to investigate these effects on the growth, competitive ability, leaf and litter chemistry, and litter decomposition of Lupinus arboreus, a N2-fixing evergreen shrub, and to test the central hypothesis that an increase in growth and competitive ability would occur at low nitrogen and high CO2. In a growth chamber experiment, three CO2 levels, 350, 500, and 650 ppm were crossed with two nitrogen levels. Lupins were grown alone or in competition with an introduced annual grass, Bromus diandrus. Contrary to findings from previous studies of positive growth and competition responses by N2-fixers, Lupinus seedlings demonstrated no significant responses to CO2. Nitrogen was far more important than CO2 in affecting relative competitive ability. Nitrogen, alkaloids, and C:N ratios in fresh foliage did not change with CO2 or nitrogen. Carbon and biomass increased slightly in lupins at 500 ppm only, suggesting an early but limited growth response. Nitrogen did decrease in lupin litter at elevated CO2, but there were no effects on litter decomposition rates in the field. Simulations by the CENTURY surface litter decomposition model predicted the litter decomposition rates of field-grown litter nearly perfectly, and predicted the general direction but underestimated the rate of litter from the greenhouse grown at different CO2 levels. Very low or high nitrogen decreased

Effect of fiber-based creep feed on intake, digestion, ruminal fermentation, and microbial efficiency in nursing calves.

PubMed

Soto-Navarro, S A; Knight, M H; Lardy, G P; Bauer, M L; Caton, J S

2004-12-01

Six Angus crossbred cow-calf pairs (653 +/- 35 kg and 157 +/- 10 kg initial BW for cows and calves, respectively) were used to evaluate the influence of a fiber-based creep feed on intake, ruminal fermentation, digestion characteristics, and microbial efficiency in nursing beef calves. Cow-calf pairs were stratified by calf age and assigned randomly to one of two treatments: control (no supplement) or supplemented. Supplemented calves received 0.9 kg of a 49% soy hulls, 44% wheat middlings, 6% molasses, and 1% limestone supplement (DM basis) daily. All calves were cannulated in the rumen and duodenum and given ad libitum access to chopped brome hay (Bromus inermus L; 7.43% CP, 40.96% ADF, and 63.99% NDF; DM basis). Supplementation was initiated on May 1 (88 +/- 10.3 d calf age). Three sampling periods were conducted throughout the study (June 14 to 25, July 5 to 16, and August 9 to 20). Supplement and forage were offered at 0800 daily. Total, hay, and milk OM intakes of nursing calves were not affected by supplementation (2,014 vs. 2,328 +/- 288.8, 1,486 vs. 1,029 +/- 3,06.9, and 528 vs. 575 +/- 87.0 g/d, respectively). Milk OM intake was less (P < 0.09) in August than in June and July (635, 691, and 345 +/- 110.6 g/d for June, July, and August, respectively). A supplementation x month interaction occurred (P < 0.10) for total-tract OM digestion. Supplementation did not affect (P > 0.40) total-tract OM digestibility during June and August; however, during July, total-tract OM digestibility was lower (P = 0.03) for the control calves. Ruminal ammonia concentration, total VFA, and butyrate molar proportion increased (P < 0.05), whereas acetate proportion decreased (P = 0.01) in supplemented calves. Microbial efficiency was not influenced by supplementation (11.8 vs. 12.0 g/kg of OM truly fermented for control and supplemented calves, respectively). These data indicate that fiber-based supplements can be used as creep feed without negative effects on OM intake, total

Root growth and function of three Mojave Desert grasses in response to elevated atmospheric CO2 concentration

USGS Publications Warehouse

Yoder, C.K.; Vivin, P.; DeFalco, L.A.; Seemann, J.R.; Nowak, R.S.

2000-01-01

Root growth and physiological responses to elevated CO2 were investigated for three important Mojave Desert grasses: the C3 perennial Achnatherum hymenoides, the C4 perennial Pleuraphis rigida and the C3 annual Bromus madritensis ssp. rubens. Seeds of each species were grown at ambient (360 μl l−1) or elevated (1000 μl l−1) CO2 in a glasshouse and harvested at three phenological stages: vegetative, anthesis and seed fill. Because P. rigida did not flower during the course of this study, harvests for this species represent three vegetative stages. Primary productivity was increased in both C3 grasses in response to elevated CO2 (40 and 19% for A. hymenoides and B. rubens, respectively), but root biomass increased only in the C3 perennial grass. Neither above-ground nor below-ground biomass of the C4 perennial grass was significantly affected by the CO2 treatment. Elevated CO2 did not significantly affect root surface area for any species. Total plant nitrogen was also not statistically different between CO2treatments for any species, indicating no enhanced uptake of N under elevated CO2. Physiological uptake capacities for NO3 and NH4 were not affected by the CO2 treatment during the second harvest; measurements were not made for the first harvest. However, at the third harvest uptake capacity was significantly decreased in response to elevated CO2 for at least one N form in each species. NO3 uptake rates were lower in A. hymenoides and P. rigida, and NH4 uptake rates were lower in B. rubens at elevated CO2. Nitrogen uptake on a whole root-system basis (NO3+NH4uptake capacity × root biomass) was influenced positively by elevated CO2 only for A. hymenoidesafter anthesis. These results suggest that elevated CO2 may result in a competitive advantage forA. hymenoides relative to species that do not increase root-system N uptake capacity. Root respiration measurements normalized to 20 °C were not significantly affected by the CO2treatment. However, specific root

The cultivation bias: different communities of arbuscular mycorrhizal fungi detected in roots from the field, from bait plants transplanted to the field, and from a greenhouse trap experiment.

PubMed

Sýkorová, Zuzana; Ineichen, Kurt; Wiemken, Andres; Redecker, Dirk

2007-12-01

The community composition of arbuscular mycorrhizal fungi (AMF) was investigated in roots of four different plant species (Inula salicina, Medicago sativa, Origanum vulgare, and Bromus erectus) sampled in (1) a plant species-rich calcareous grassland, (2) a bait plant bioassay conducted directly in that grassland, and (3) a greenhouse trap experiment using soil and a transplanted whole plant from that grassland as inoculum. Roots were analyzed by AMF-specific nested polymerase chain reaction, restriction fragment length polymorphism screening, and sequence analyses of rDNA small subunit and internal transcribed spacer regions. The AMF sequences were analyzed phylogenetically and used to define monophyletic phylotypes. Overall, 16 phylotypes from several lineages of AMF were detected. The community composition was strongly influenced by the experimental approach, with additional influence of cultivation duration, substrate, and host plant species in some experiments. Some fungal phylotypes, e.g., GLOM-A3 (Glomus mosseae) and several members of Glomus group B, appeared predominantly in the greenhouse experiment or in bait plants. Thus, these phylotypes can be considered r strategists, rapidly colonizing uncolonized ruderal habitats in early successional stages of the fungal community. In the greenhouse experiment, for instance, G. mosseae was abundant after 3 months, but could not be detected anymore after 10 months. In contrast, other phylotypes as GLOM-A17 (G. badium) and GLOM-A16 were detected almost exclusively in roots sampled from plants naturally growing in the grassland or from bait plants exposed in the field, indicating that they preferentially occur in late successional stages of fungal communities and thus represent the K strategy. The only phylotype found with high frequency in all three experimental approaches was GLOM A-1 (G. intraradices), which is known to be a generalist. These results indicate that, in greenhouse trap experiments, it is difficult

Microbial decomposition of dead grassland roots and its influence on the carbon cycle under changing precipitation patterns

NASA Astrophysics Data System (ADS)

Becerra, C.; Schimel, J.

2013-12-01

Soil is the largest reservoir of organic carbon in terrestrial ecosystems and as such, represents a potential sink for carbon dioxide.The decomposition products of dead roots buried in the soil is a contributor to soil organic carbon. However, changing precipitation patterns may affect its fate by influencing the microbial community responsible for decomposing dead roots. To assess the impact of changing precipitation patterns, we constructed microcosms with grassland soil collected from the UCSB Sedgwick Reserve, an active and long-term research site, and dead roots from greenhouse-grown grass, Bromus diandrus. Microcosms were wetted continuously, every seven days, or every twenty days. Sets of microcosms were periodically deconstructed to assess the soil versus the roots-associated microbial community and its function. Differences in respiration rates of microcosms continuously wetted or wetted every 7 days versus microcosms wetted every 20 days existed for the first 70 days. After which, no differences in respiration rates were seen with microcosms containing roots and the no roots control. Relatedly, after a 70% roots mass loss by day 50, there was no difference in the respiration rate of microcosms containing roots and the no roots control. More than half of the roots mass loss had occurred by 30 days. By the end of the incubation period, the roots mass loss in continuously wet and 7-day wetted microcosms were over 80% compared to 67% for the microcosms wetted every 20 days. Microbial biomass in the soil were constant over time and showed no difference in treatment except with the no roots control during the first half of the incubation period. Hydrolytic enzyme activities (β-1,4-glucosidase; α-1,4-glucosidase; β-1,4-xylosidase; β-1,4-cellobiosidase) on the roots versus the soil attached to the roots were over an order greater and decreased faster with the exception of N-acetyl-glucosaminidase and acid phosphatase. Oxidative enzyme activities (phenol

U.S. Geological Survey science for the Wyoming Landscape Conservation Initiative—2016 annual report

USGS Publications Warehouse

Bowen, Zachary H.; Aikens, Ellen; Aldridge, Cameron L.; Anderson, Patrick J.; Assal, Timothy J.; Chalfoun, Anna D.; Chong, Geneva W.; Eddy-Miller, Cheryl; Garman, Steven L.; Germaine, Stephen S.; Homer, Collin G.; Johnston, Aaron; Kauffman, Matthew J.; Manier, Daniel J.; Melcher, Cynthia P.; Miller, Kirk A.; Walters, Annika W.; Wheeler, Jerrod D.; Wieferich, Daniel; Wilson, Anna B.; Wyckoff, Teal B.; Zeigenfuss, Linda C.

2018-05-10

was in review at the end of the fiscal year, and seven projects monitoring water and vegetation (including changes in sagebrush cover and patterns of sagebrush mortality) continued through the year. USGS scientists continued many projects in FY2016 that evaluate the effectiveness of habitat conservation actions (including sagebrush, cheatgrass, and aspen habitat treatments) and provide tools in support of mechanistic studies of wildlife. In FY2016, USGS scientists, along with university and State partners, continued work on five focal wildlife species/communities (pygmy rabbits [Brachylagus idahoensis], greater sage grouse , mule deer, sagebrush songbirds, and native fish). In FY2016, the USGS Information Management Team presented information to WLCI scientists on how USGS tools and resources can be used to fulfill the requirements of new USGS policies regarding data release, data management, and data visualization.

An ethnobotanical survey of traditionally used plants on Suva planina mountain (south-eastern Serbia).

PubMed

Jarić, Snežana; Mačukanović-Jocić, Marina; Djurdjević, Lola; Mitrović, Miroslava; Kostić, Olga; Karadžić, Branko; Pavlović, Pavle

2015-12-04

This study documents the ethnobotanical and ethnomedicinal importance of plants in the Suva planina mountain region (south-eastern Serbia). It is reflected in their high diversity and their wide range of uses in the treatment of the local population. The aim of this study was a comparative analysis of data collected in the Suva planina region with relevant data from the Western Balkans, which included identifying the 'most popular' plants, as well as those species which are used specifically for treatment solely in the research area. Ethnobotanical research was carried out between 2012 and 2014 and data was collected through both open and semi-structured interviews with locals. A total of 66 people were interviewed (37 women and 29 men), aged between 49 and 90 (with a mean age of 71). This study identified 128 plants and 2 fungi which are used in ethnomedicine, 5 plant species used in ethnoveterinary medicine, and 16 plants used for 'other' purposes. Lamiaceae (20), Asteraceae (17), Rosaceae (16), Brassicaceae (5), Alliaceae (4) and Apiaceae (4) have the greatest diversity of species. Results showed that Achillea mellefolium, Allium cepa, Allium sativum, Arctostaphyllos uva-ursi, Gentiana lutea, Hypericum perforatum, Juglans regia, Matricaria chamomilla, Mentha piperita, Plantago lanceolata, Plantago major, Salvia officinalis, Sempervivum tectorum, Tilia cordata and Thymus sepyllum are the 'most popular' medicinal plants (UV=1). Those plants with the most phytotherapeutic uses are Gentiana cruciata (14), H. perforatum (11) and A. sativum (10), while the most common conditions treated with medicinal plants are respiratory (79), urogenital (53), gastrointestinal (51), skin (43) and those relating to the circulatory system (35). A comparative analysis of the data collected in the research area and that from other parts of the Western Balkans showed that there are great similarities within Serbia between Suva planina and the Zlatibor region (37.2%) and Kopaonik Mt. (32

Impacts of climate on shrubland fuels and fire behavior in the Owyhee Basin, Idaho

NASA Astrophysics Data System (ADS)

Vogelmann, J. E.; Shi, H.; Hawbaker, T.; Li, Z.

2013-12-01

There is evidence that wildland fire is increasing as a function of global change. However, fire activity is spatially, temporally and ecologically variable across the globe, and our understanding of fire risk and behavior in many ecosystems is limited. After a series of severe fire seasons that occurred during the late 1990's in the western United States, the LANDFIRE program was developed with the goals of providing the fire community with objective spatial fuel data for assessing wildland fire risk. Even with access to the data provided by LANDFIRE, assessing fire behavior in shrublands in sagebrush-dominated ecosystems of the western United States has proven especially problematic, in part due to the complex nature of the vegetation, the variable influence of understory vegetation including invasive species (e.g. cheatgrass), and prior fire history events. Climate is undoubtedly playing a major role, affecting the intra- and inter-annual variability in vegetation conditions, which in turn impacts fire behavior. In order to further our understanding of climate-vegetation-fire interactions in shrublands, we initiated a study in the Owyhee Basin, which is located in southwestern Idaho and adjacent Nevada. Our goals include: (1) assessing the relationship between climate and vegetation condition, (2) quantifying the range of temporal variability in grassland and shrubland fuel loads, (3) identifying methods to operationally map the variability in fuel loads, and (4) assessing how the variability in fuel loads affect fire spread simulations. To address these goals, we are using a wide variety of geospatial data, including remotely sensed time-series data sets derived from MODIS and Landsat, and climate data from DAYMET and PRISM. Remotely-sensed information is used to characterize climate-induced temporal variability in primary productivity in the Basin, where fire spread can be extensive after senescence when dry vegetation is added to dead fuel loads. Gridded

An In-Situ Root-Imaging System in the Context of Surface Detection of CO2

NASA Astrophysics Data System (ADS)

Apple, M. E.; Prince, J. B.; Bradley, A. R.; Zhou, X.; Lakkaraju, V. R.; Male, E. J.; Pickles, W.; Thordsen, J. J.; Dobeck, L.; Cunningham, A.; Spangler, L.

2009-12-01

Carbon sequestration is a valuable method of spatially confining CO2 belowground. The Zero Emissions Research Technology, (ZERT), site is an experimental facility in a former agricultural field on the Montana State University campus in Bozeman, Montana, where CO2 was experimentally released at a rate of 200kg/day in 2009 into a 100 meter underground injection well running parallel to the ground surface. This injection well, or pipe, has deliberate leaks at intervals, and CO2 travels from these leaks upward to the surface of the ground. The ZERT site is a model system designed with the purpose of testing methods of surface detection of CO2. One important aspect of surface detection is the determination of the effects of CO2 on the above and belowground portions of plants growing above sequestration fields. At ZERT, these plants consist of a pre-existing mixture of herbaceous species present at the agricultural field. Species growing at the ZERT site include several grasses, Dactylis glomerata (Orchard Grass), Poa pratensis (Kentucky Bluegrass), and Bromus japonicus (Japanese Brome); the nitrogen-fixing legumes Medicago sativa, (Alfalfa), and Lotus corniculatus, (Birdsfoot trefoil); and an abundance of Taraxacum officinale, (Dandelion). Although the aboveground parts of the plants at high CO2 are stressed, as indicated by changes in hyperspectral plant signatures, leaf fluorescence and leaf chlorophyll content, we are interested in determining whether the roots are also stressed. To do so, we are combining measurements of soil conductivity and soil moisture with root imaging. We are using an in-situ root-imaging system manufactured by CID, Inc. (Camas, WA), along with image analysis software (Image-J) to analyze morphometric parameters in the images and to determine what effects, if any, the presence of leaking and subsequently upwelling CO2 has on the phenology of root growth, growth and turnover of individual fine and coarse roots, branching patterns, and root

Hydrological behavior of a Vertisol under different soil management systems in a rain-fed olive orchard

NASA Astrophysics Data System (ADS)

Cabezas, Jose Manuel; Gómez, Jose Alfonso; Auxiliadora Soriano, María

2016-04-01

Soil water availability is a major subject in Mediterranean agricultural systems, mainly due to the limited and highly variable annual rainfall, high evaporative demand, and soil hydrological characteristics. The recent expansion of olive cultivation in the rolling-plains of the Guadalquivir valley, due to the higher profitability of new intensive olive orchards, expanded the presence of olive orchards on Vertisols, soils traditionally used for annual rain-fed crops. These soils have a high content of smectitic clays, which give them a high water storage capacity, and are characterized by vertical and deep shrinkage cracks in the dry season, associated to low soil moisture. Farmers make several tillage passes in these olive groves during the summer, in order to cover the cracks and thus reduce soil water loss by evaporation, which will impact especially in rain-fed in the next olive yield. This tillage practice involves removal of plant residues from the soil surface, as well as burying seeds produced by the plants, so this will remain bared at the beginning of the rainy season, when in the Mediterranean climate is frequent occurrence of high-intensity rainfall, which are ideal conditions for soil loss by water erosion, one of the most serious problems for the sustainability of olive cultivation in Andalusia. Although there are some studies showing that water loss by evaporation from deep horizons of a vertic soil might be elevated (eg. Ritchie and Adams, 1974), the presence of plant residues on the soil surface drastically reduced soil water loss (eg Adams et al., 1969). Thus the aim of this study was to assess of soil moisture dynamics in a rain-fed olive orchard growing on a Vertisol under different soil management practices, in Andalusia (southern Spain). Four different soil management treatments were applied, which combined a cover crop (Bromus rubens L.) or bare soil throughout the year by applying herbicides, with tillage in summer to cover the cracks or non

Evapotranspiration and microclimate at a low-level radioactive-waste disposal site in northwestern Illinois

USGS Publications Warehouse

Healy, R.W.; DeVries, M.P.; Sturrock, Alex M.

1989-01-01

From July 1982 through June 1984, a study was made of the evapotranspiration and microclimate at a low-level radioactive-waste disposal site near Sheffield, Bureau County, Illinois. Vegetation at the site consists of mixed pasture grasses, primarily awnless brome (Bromus inermis) and red clover (Trifoleum pratense). Three methods were used to estimate evapotranspiration: (1) an energy budget with the Bowen ratio, (2) an aerodynamic profile, and (3) a soil-based water budget. For the aerodynamic-profile method, sensible-heat flux was estimated by a profile equation and evapotranspiration was then calculated as the residual in the energy-balance equation. Estimates by the energy-budget and aerodynamic-profile methods were computed from hourly data and then summed by days and months. Yearly estimates (for March through November) by these methods were in close agreement: 648 and 626 millimeters, respectively. Daily estimates reach a maximum of about 6 millimeters. The water-budget method produced only monthly estimates based on weekly or biweekly soil-moisture content measurements. The yearly evapotranspiration estimated by this method (which actually included only the months of April through October) was 655 millimeters. The March-through-November average for the three methods of 657 millimeters was equivalent to 70 percent of total precipitation. Continuous measurements were made of incoming and reflected shortwave radiation, incoming and emitted longwave radiation, net radiation, soil-heat flux, soil temperature, horizontal windspeed, and wet- and dry-bulb air temperature. Windspeed and air temperature were measured at heights of 0.5 and 2.0 meters (and also at 1.0 meter after September 1983). Soilmoisture content of the soil zone was measured with a gamma-attenuation gage. Annual precipitation (938 millimeters) and average temperature (10.8 degrees Celsius) at the Sheffield site were virtually identical to long-term averages from nearby National Weather Service

Effects of increased soil nitrogen on the dominance of alien annual plants in the Mojave Desert

USGS Publications Warehouse

Brooks, Matthew L.

2003-01-01

1. Deserts are one of the least invaded ecosystems by plants, possibly due to naturally low levels of soil nitrogen. Increased levels of soil nitrogen caused by atmospheric nitrogen deposition may increase the dominance of invasive alien plants and decrease the diversity of plant communities in desert regions, as it has in other ecosystems. Deserts should be particularly susceptible to even small increases in soil nitrogen levels because the ratio of increased nitrogen to plant biomass is higher compared with most other ecosystems.2. The hypothesis that increased soil nitrogen will lead to increased dominance by alien plants and decreased plant species diversity was tested in field experiments using nitrogen additions at three sites in the in the Mojave Desert of western North America.3. Responses of alien and native annual plants to soil nitrogen additions were measured in terms of density, biomass and species richness. Effects of nitrogen additions were evaluated during 2 years of contrasting rainfall and annual plant productivity. The rate of nitrogen addition was similar to published rates of atmospheric nitrogen deposition in urban areas adjacent to the Mojave Desert (3·2 g N m−2 year−1). The dominant alien species included the grasses Bromus madritensis ssp. rubens and Schismus spp. (S. arabicus and S. barbatus) and the forb Erodium cicutarium.4. Soil nitrogen addition increased the density and biomass of alien annual plants during both years, but decreased density, biomass and species richness of native species only during the year of highest annual plant productivity. The negative response of natives may have been due to increased competitive stress for soil water and other nutrients caused by the increased productivity of aliens.5. The effects of nitrogen additions were significant at both ends of a natural nutrient gradient, beneath creosote bush Larrea tridentata canopies and in the interspaces between them, although responses varied among

Evapotranspiration and microclimate at a low-level radioactive-waste disposal site in northwestern Illinois

USGS Publications Warehouse

Healy, R.W.; DeVries, M.P.; Sturrock, A.M.

1987-01-01

From July 1982 through June 1984, a study was made of the microclimate and evapotranspiration at a low-level radioactive-waste disposal site near Sheffield, Bureau County, Illinois. Vegetation at the site consists of mixed pasture grasses, primarily brome (Bromus inermis) and red clover (Trifoleum pratense). Three methods were used to estimate evapotranspiration: (1) an energy-budget with the Bowen ratio, (2) an aerodynamic-profile, and (3) a soil-based water-budget. For the aerodynamic-profile method, sensible-heat flux was estimated by a profile equation and evapotranspiration was then calculated as the residual in the energy-balance equation. Estimates by the energy-budget and aerodynamic-profile methods were computed from hourly data, then summed by days and months. Yearly estimates for March through November, by these methods, were quite close--648 and 626 millimeters, respectively. Daily estimates range up to a maximum of about 6 millimeters. The water-budget method produced only monthly estimates based on weekly or biweekly soil-moisture content measurements. The yearly evapotranspiration estimated by this method (which actually included only the months of April through October) was 655 millimeters. The March-through-November average for the three methods of 657 millimeters was equivalent to 70 percent of precipitation. Continuous measurements were made of incoming and reflected shortwave radiation, incoming and emitted longwave radiation, net radiation, soil-heat flux, soil temperature, horizontal windspeed, and wet- and dry-bulb air temperature. Windspeed and air temperature were measured at heights of 0.5 and 2.0 meters (and also at 1.0 meter after September 1983). Soil-moisture content of the soil zone was measured with a gamma-attenuation gage. Annual precipitation (938 millimeters) and average temperature (10.8 degrees Celsius) were virtually identical to long-term averages from nearby National Weather Service stations. Solar radiation averaged 65

Plants as Indicators of Past and Present Zones of Upwelling Soil CO2 at the ZERT Facility

NASA Astrophysics Data System (ADS)

Apple, M. E.; Sharma, B.; Zhou, X.; Shaw, J. A.; Dobeck, L.; Cunnningham, A.; Spangler, L.; ZERT Team

2011-12-01

By their very nature, photosynthetic plants are sensitive and responsive to CO2, which they fix during the Calvin-Benson cycle. Responses of plants to CO2 are valuable tools in the surface detection of upwelling and leaking CO2 from carbon sequestration fields. Plants exposed to upwelling CO2 rapidly exhibit signs of stress such as changes in stomatal conductance, hyperspectral signatures, pigmentation, and viability (Lakkaraju et al. 2010; Male et al. 2010). The Zero Emission Research and Technology (ZERT) site in Bozeman, MT is an experimental facility for surface detection of CO2 where 0.15 ton/day of CO2 was released (7/19- 8/15/2010, and 7/18 - 8/15/2011) from a 100m horizontal injection well, (HIW), 1.5 m underground with deliberate leaks of CO2 at intervals, and from a vertical injector, (VIW), (6/3-6/24/2010). Soil CO2 concentrations reached 16%. Plants at ZERT include Taraxacum officinale (Dandelion), Dactylis glomerata (Orchard Grass), Poa pratensis, (Kentucky Bluegrass), Phleum pratense (Timothy), Bromus japonicus (Japanese Brome), Medicago sativa (Alfalfa) and Cirsium arvense (Canadian Thistle). Dandelion leaves above the zones of upwelling CO2 at the HIW and the VIW changed color from green to reddish-purple (indicative of an increase in anthocyanins) to brown as they senesced within two weeks of CO2 injection. Their increased stomatal conductance along with their extensive surface area combined to make water loss occur quickly following injection of CO2. Xeromorphic grass leaves were not as profoundly affected, although they did exhibit changes in stomatal conductance, accelerated loss of chlorophyll beyond what would normally occur with seasonal senescence, and altered hyperspectral signatures. Within two weeks of CO2 injection at the HIW and the VIW, hot spots formed, which are circular zones of visible leaf senescence that appear at zones of upwelling CO2. The hot spots became more pronounced as the CO2 injection continued, and were detectable

Caesium-137 soil-to-plant transfer for representative agricultural crops of monocotyledonous and dicotyledonous plants in post-Chernobyl steppe landscape

NASA Astrophysics Data System (ADS)

Paramonova, Tatiana; Komissarova, Olga; Turykin, Leonid; Kuzmenkova, Natalia; Belyaev, Vladimir

2016-04-01

The accident at the Chernobyl nuclear power plant in 1986 had a large-scale action on more than 2.3 million hectares agricultural lands in Russia. The area of radioactively contaminated chernozems of semi-arid steppe zone with initial levels of Cs-137 185-555 kBq/m2 in Tula region received the name "Plavsky radioactive hotspot". Nowadays, after the first half-life period of Cs-137 arable chernozems of the region are still polluted with 3-6-fold excess above the radioactive safety standard (126-228 kBq/m2). Therefore, qualitative and quantitative characteristics of Cs-137 soil-to-plant transfer are currently a central problem for land use on the territory. The purpose of the present study was revealing the biological features of Cs-137 root uptake from contaminated arable chernozems by different agricultural crops. The components of a grass mixture growing at the central part of Plavsky radioactive hotspot with typical dicotyledonous and monocotyledonous plants - galega (Galega orientalis, Fabaceae family) and bromegrass (Bromus inermis, Gramineae family) respectively - were selected for the investigation, that was conducted during the period of harvesting in 2015. An important point was that the other factors influenced on Cs-137 soil-to-plant transfer - the level of soil pollution, soil properties, climatic conditions, vegetative phase, etc. - were equal. So, biological features of Cs-137 root uptake could be estimated the most credible manner. As a whole, general discrimination of Cs-137 root uptake was clearly shown for both agricultural crops. Whereas Cs-137 activity in rhizosphere 30-cm layer of arable chernozem was 371±74 Bq/kg (140±32 kBq/m2), Cs-137 activities in plant biomass were one-two orders of magnitude less, and transfer factor (TF) values (the ratio of the Cs-137 activities in vegetation and in soil) not exceeded 0.11. At the same time bioavailability of Cs-137 for bromegrass was significantly higher than for galega: TFs in total biomass of the

Rolled lawn as tool for industrial barren remediation

NASA Astrophysics Data System (ADS)

Gorbacheva, T. T.; Ivanova, L. A.; Kikuchi, R.; Gerardo, R.

2009-04-01

term of cultivation (from 1 to 16 July 2008). Rolled lawn was characterized by high plant density 759.0±12.2 units per m2. That parameter achievement is not possible using traditional way of direct seeding in prepared ground that is common in Kola Peninsula region. Mass of 1 m2 rolled lawn is about 5-7 kg. Rolled lawn cost is sufficiently lower than traditional (turf-grounded) one. Grass seeds were choose as more adaptive for severe conditions and suitable for recultivation tasks: Festuca rubra L. - 44.4%, Bromus inermis Leyss. - 33.4%, Festulolium smaragdinum - 11.1%, Festuca pratensis Huds.- 11.1%. Field experiment was carried out in three variants (1- mineral ground - flat site; 2- mineral ground- slope sites; 3- organogenic ground - flat site in depression in five replicates. Growing in very contaminated ground resulted in 50% rolled lawn surface loss but with biodiversity maintenance. Grass roots proliferated in contaminated ground very slowly. It seems obvious that plant roots choose the best zones of soils to grow, and that they avoided toxic zones. More comprehensive results were received for mineral ground due to better natural washing compared to organogenic ground. In all variants we observed secondary roots formation. Simultaneously with rolled lawn placement litterbag experiment was carried out with original vermiculite as filling. Short term (July- September 2008) alteration of nutritional status and contamination level of vermiculite was controlled and compared with quartz as inert material. Observations will continue during 2009-2011 to follow freezing influence and nutrient loss rate.

Fusarium crown rot caused by Fusarium pseudograminearum in cereal crops: recent progress and future prospects.

PubMed

Kazan, Kemal; Gardiner, Donald M

2017-11-04

Hypocreales; Family Nectriaceae; Genus Fusarium. Disease symptoms: Fusarium crown rot caused by F. pseudograminearum is also known as crown rot, foot rot and root rot. Infected seedlings can die before or after emergence. If infected seedlings survive, typical disease symptoms are browning of the coleoptile, subcrown internode, lower leaf sheaths and adjacent stems and nodal tissues; this browning can become evident within a few weeks after planting or throughout plant development. Infected plants may develop white heads with no or shrivelled grains. Disease symptoms are exacerbated under water limitation. Identification and detection: Fusarium pseudograminearum macroconidia usually contain three to five septa (22-60.5 × 2.5-5.5 μm). On potato dextrose agar (PDA), aerial mycelia appear floccose and reddish white, with red or reddish-brown reverse pigmentation. Diagnostic polymerase chain reaction (PCR) tests based on the amplification of the gene encoding translation elongation factor-1a (TEF-1a) have been developed for molecular identification. Host range: All major winter cereals can be colonized by F. pseudograminearum. However, the main impact of this pathogen is on bread (Triticum aestivum L.) and durum (Triticum turgidum L. spp. durum (Dest.)) wheat and barley (Hordeum vulgare L.). Oats (Avena sativa L.) can be infected, but show little or no disease symptoms. In addition, the pathogen has been isolated from various other grass genera, such as Phalaris, Agropyron and Bromus, which may occur as common weeds. Useful websites: https://nt.ars-grin.gov/fungaldatabases/; http://plantpath.psu.edu/facilities/fusarium-research-center; https://nt.ars-grin.gov/fungaldatabases/; http://www.speciesfungorum.org/Names/Names.asp. © 2017 BSPP AND JOHN WILEY & SONS LTD.

Results of hydrologic research at a low-level radioactive-waste disposal site near Sheffield, Illinois

USGS Publications Warehouse

Ryan, Barbara J.

1989-01-01

budget. Although monthly totals for each method differed, estimated annual evapotranspiration averages ranged from 630 to 693 millimeters or about 70 percent of precipitation. Tritium concentrations in leaf water from on-site plants were determined for 125 vegetation samples collected during the summers of 1982 through 1986. Concentrations varied significantly among some locations and plant types. Tritium concentrations ranged from the detection limit of 0 .2 to 1,330 nanocuries per liter, with alfalfa (Medicago sativa) having the highest concentrations, followed by brome grass (Bromus inermis), and then red clover (Trifoleum pratense); these variations in concentration are most likely a result of root depth. Runoff and sediment transport were measured from July 1982 through December 1985 in four basins--three comprising almost two-thirds of the 8.1-hectare site and one comprising a 1.4-hectare undisturbed area. Volumes and equivalent weights of collapses were estimated from records of site surficial conditions from October 1978 through December 1985. Runoff showed a direct relation to degree of land modification; lowest mean yields were measured at the undisturbed area, and highest mean yields were measured from the basin composed wholly of trench and intertrench areas. Sediment yield measured onsite averaged 3.4 megagrams per hectare. A total of 315 collapse cavities, corresponding to a cumulative volume of about 500 cubic meters, were documented. Most collapses were recorded after periods of rainfall or snowmelt when soil moisture was near maximum. Almost two-thirds of the collapses, corresponding to 63 percent of the cumulative cavity volume, occurred during February through April. Data for the study of water movement through a trench cover were collected from July 1982 through June 1934. Pressure-head data were collected at four different clusters at depths ranging from 50 to 1,850 millimeters within a selected trench cover. Soil-moisture content f

Vascular Plant and Vertebrate Inventory of Gila Cliff Dwellings National Monument

USGS Publications Warehouse

Powell, Brian F.; Albrecht, Eric W.; Halvorson, William L.; Schmidt, Cecilia A.; Docherty, Kathleen; Anning, Pamela

2006-01-01

Executive Summary This report summarizes the results of the first comprehensive biological inventory of Gila Cliff Dwellings National Monument (NM) in western New Mexico. This project was part of a larger effort to inventory plants and vertebrates in eight National Park Service units in Arizona and New Mexico. Our surveys address many of the objectives that were set forth in the monument's natural resource management plan almost 20 years ago, but until this effort, those goals were never accomplished. From 2001 to 2003 we surveyed for vascular plants and vertebrates (amphibians, reptiles, birds, and mammals) at Gila Cliff Dwellings NM to document presence of species within the boundaries of the monument. For all taxonomic groups that we studied, we collected 'incidental' sightings on U.S. Forest Service lands adjacent to the monument, and in a few cases we did formal surveys on those lands. Because we used repeatable study designs and standardized field techniques, these inventories can serve as the first step in a biological monitoring program for Gila Cliff Dwellings NM and surrounding lands. We recorded 552 species at Gila Cliff Dwellings NM and the surrounding lands (Table 1). We found no non-native species of reptiles, birds, or mammals, one non-native amphibian (American bullfrog), and 33 non-native plants. Particularly on lands adjacent to the monument we found that the American bullfrog was very abundant, which is a cause for significant management concern. Species of non-native plants that are of management concern include red brome, bufflegrass, and cheatgrass. For a park unit of its size and geographic location, we found the plant and vertebrate communities to be fairly diverse; for each taxonomic group we found representative species from a wide range of taxonomic orders and/or families. The monument's geographic location, with influences from the Rocky Mountain, Chihuahuan Desert, and Madrean ecological provinces, plays an important role in determining

Conservation reserve program: benefit for grassland birds in the northern plains

USGS Publications Warehouse

Reynolds, R.E.; Shaffer, T.L.; Sauer, J.R.; Peterjohn, B.G.

1994-01-01

cropland in some counties has been converted primarily to grass. In North Dakota, nearly 3 million acres have been enrolled. Over 90 percent of the CRP plantings in North Dakota are grass and grass-legume mix composed primarily of wheatgrass (Agropyron spp.), smooth brome (Bromus inermis), alfalfa (Medicago saliva) and sweetclover (Melilotus spp.). Mixes of these species have been reported to attract high densities of nesting ducks (Duebbert and Kantrud 1974). According to the CRP provisions, the land must remain idle for the 10-year contract period, with the exception of emergency provisions for haying or grazing. CRP appears to have great potential for benefiting many species of grassland-nesting birds. There have been efforts to document the importance of the CRP to migratory birds in the Upper Great Plains of the U.S. Kantrud (1993) studied duck nest success in CRP cover and concluded that nest success was higher than in planted cover on U.S. Fish and Wildlife Service (FWS) Waterfowl Production Areas (WPAs). Johnson and Schwartz (1993a) measured the use of CRP fields by nonwaterfowl birds and reported that several species have responded positively by colonizing CRP fields. They concluded that CRP has the potential to help reverse the population declines of several species. We investigated the importance of CRP to upland-nesting ducks and certain other grassland-nesting birds. For ducks, we compared nest success in CRP cover with nest success in planted cover on WPAs in the same period (1992-93) and with that of an earlier period (1980-84). For nonwaterfowl, we used BBS data to compare the trends in populations of certain species found in CRP, for the periods 1966-86 (pre-CRP cover establishment) and 1987-92 (post-CRP cover establishment) in North Dakota.

Pyrenophora teres: profile of an increasingly damaging barley pathogen.

PubMed

Liu, Zhaohui; Ellwood, Simon R; Oliver, Richard P; Friesen, Timothy L

2011-01-01

. Conidia measuring 30-174µm × 15-23µm are smoothly cylindrical and straight, round at both ends, subhyaline to yellowish brown, often with four to six pseudosepta. Morphologically, P. teres f. teres and P. teres f. maculata are indistinguishable. Comprehensive work on the host range of P. teres f. teres has been performed; however, little information on the host range of P. teres f. maculata is available. Hordeum vulgare and H. vulgare ssp. spontaneum are considered to be the primary hosts for P. teres. However, natural infection by P. teres has been observed in other wild Hordeum species and related species from the genera Bromus, Avena and Triticum, including H. marinum, H. murinum, H. brachyantherum, H. distichon, H. hystrix, B. diandrus, A. fatua, A. sativa and T. aestivum (Shipton et al., 1973, Rev. Plant Pathol. 52:269-290). In artificial inoculation experiments under field conditions, P. teres f. teres has been shown to infect a wide range of gramineous species in the genera Agropyron, Brachypodium, Elymus, Cynodon, Deschampsia, Hordelymus and Stipa (Brown et al., 1993, Plant Dis. 77:942-947). Additionally, 43 gramineous species were used in a growth chamber study and at least one of the P. teres f. teres isolates used was able to infect 28 of the 43 species tested. However, of these 28 species, 14 exhibited weak type 1 or 2 reactions on the NFNB 1-10 scale (Tekauz, 1985). These reaction types are small pin-point lesions and could possibly be interpreted as nonhost reactions. In addition, the P. teres f. teres host range was investigated under field conditions by artificially inoculating 95 gramineous species with naturally infected barley straw. Pyrenophora teres f. teres was re-isolated from 65 of the species when infected leaves of adult plants were incubated on nutrient agar plates; however, other than Hordeum species, only two of the 65 host species exhibited moderately susceptible or susceptible field reaction types, with most species showing small dark

Fire rehabilitation effectiveness: a chronosequence approach for the Great Basin

USGS Publications Warehouse

Pyke, David A.; Pilliod, David S.; Chambers, Jeanne C.; Brooks, Matthew L.; Grace, James

2009-01-01

was positively related to plot- and landscape-level dwarf sagebrush (Artemisia arbuscula, A. nova, A. tripartita) and big sagebrush steppe, and negatively associated with non-native grass and human development. The predicted probability of sage-grouse occupancy at treated plots was low on average (0.07–0.09) and was not significantly different from burned areas that had not been treated. Restoration was more often successful at higher elevation sites with low annual temperatures, high spring precipitation, and high plant diversity. No plots seeded after fire (n=313) met all overstory guidelines for breeding habitats, but approximately 50% met understory guidelines, particularly for perennial grasses. This trend was similar for summer habitat. Ninety-eight percent of treated plots did not meet winter habitat guidelines. Restoration actions in burned areas did not increase the probability of meeting most guideline criteria. The probability of meeting guidelines was influenced by a latitudinal gradient, local climate, and topography. Post-fire seeding treatments in Great Basin sagebrush shrublands generally have not created high quality habitat for sage-grouse. Understory conditions are more likely to be adequate than those of overstory, but in unfavorable climates, establishing forbs and reducing cheatgrass dominance is unlikely. Reestablishing sagebrush cover will require more than 20 years using the restoration methods of the past two decades. Given current fire frequencies and restoration capabilities, protection of landscapes containing a mix of dwarf sagebrush and big sagebrush steppe, minimal human development, and low non-native plant cover may provide the best opportunity for conservation of sage-grouse habitats. Our database of ES&R locations has used the Land Treatment Digital Library to archive data and location information regarding our study (see Pilliod and Welty 2013). This has contributed to two additional studies. One examined the potential spread of

Native Prairie Adaptive Management: a multi region adaptive approach to invasive plant management on Fish and Wildlife Service owned native prairies

USGS Publications Warehouse

Gannon, Jill J.; Shaffer, Terry L.; Moore, Clinton T.

2013-01-01

Much of the native prairie managed by the U.S. Fish and Wildlife Service (FWS) in the Prairie Pothole Region (PPR) of the northern Great Plains is extensively invaded by the introduced cool-season grasses, smooth brome (Bromus inermis) and Kentucky bluegrass (Poa pratensis). Management to suppress these invasive plants has had poor to inconsistent success. The central challenge to managers is selecting appropriate management actions in the face of biological and environmental uncertainties. In partnership with the FWS, the U.S. Geological Survey (USGS) developed an adaptive decision support framework to assist managers in selecting management actions under uncertainty and maximizing learning from management outcomes. This joint partnership is known as the Native Prairie Adaptive Management (NPAM) initiative. The NPAM decision framework is built around practical constraints faced by FWS refuge managers and includes identification of the management objective and strategies, analysis of uncertainty and construction of competing decision models, monitoring, and mechanisms for model feedback and decision selection. Nineteen FWS field stations, spanning four states of the PPR, have participated in the initiative. These FWS cooperators share a common management objective, available management strategies, and biological uncertainties. Though the scope is broad, the initiative interfaces with individual land managers who provide site-specific information and receive updated decision guidance that incorporates understanding gained from the collective experience of all cooperators. We describe the technical components of this approach, how the components integrate and inform each other, how data feedback from individual cooperators serves to reduce uncertainty across the whole region, and how a successful adaptive management project is coordinated and maintained on a large scale. During an initial scoping workshop, FWS cooperators developed a consensus management objective