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Bromus (Poaceae Bromeae) is a forage grass with high adaptability and ecological and economic value. Here, we sequenced Bromus ciliatus, Bromus benekenii, Bromus riparius, and Bromus rubens chloroplast genomes and compared them with four previously described species. The genome sizes of Bromus species ranged from 136,934 bp (Bromus vulgaris) to 137,189 bp (Bromus ciliates, Bromus biebersteinii), with a typical quadripartite structure. The studied species had 129 genes, consisting of 83 protein-coding, 38 tRNA-coding, and 8 rRNA-coding genes. The highest GC content was found in the inverted repeat (IR) region (43.85–44.15%), followed by the large single-copy (LSC) region (36.25–36.65%) and the small single-copy (SSC) region (32.21–32.46%). There were 33 high-frequency codons, with those ending in A/U accounting for 90.91%. A total of 350 simple sequence repeats (SSRs) were identified, with single-nucleotide repeats being the most common (61.43%). A total of 228 forward and 141 palindromic repeats were identified. No reverse or complementary repeats were detected. The sequence identities of all sequences were very similar, especially with respect to the protein-coding and inverted repeat regions. Seven highly variable regions were detected, which could be used for molecular marker development. The constructed phylogenetic tree indicates that Bromus is a monophyletic taxon closely related to Triticum. This comparative analysis of the chloroplast genome of Bromus provides a scientific basis for species identification and phylogenetic studies. [ABSTRACT FROM AUTHOR]

The effects of fire seasonality and prescribed burning on exotic species invasion are poorly understood in black greasewood (Sarcobatus vermiculatus) plant communities of North America. The impacts of reintroducing fire in the fall and spring on community composition and current-year biomass were evaluated at two such sites, one dominated by exotic annual C3 grasses in Miles City, Montana, USA, and one dominated by native perennial C4 grasses in Laramie, Wyoming, USA. Study sites were assessed based on existing Ecological Site Description (ESD) and State-and-Transition Models (STMs) and the Montana site was determined to be more degraded than the Wyoming site. Experimental design was a randomized complete block design with burns conducted in the fall of 2020 and spring of 2021. Exotic species such as Bromus arvensis were reduced by 56% in spring burned plots the following year and by 25% in the fall burned plots over the course of the study in Montana (58.3–43.5%) and Bromus tectorum did not increase in spring or fall burned plots in Wyoming. Accordingly, the proportion of native species in both plant communities remained constant and native perennial C4 grasses such as Sporobolus airoides were resilient to fire. Moreover, burn treatment had no negative effects on plant species richness, evenness, or diversity in either location. Fire treatments had variable effects on current-year biomass with variable influences of drought and season of burn. Prescribed fire, regardless of season, did not exacerbate exotic plant species spread or reduce native species dominance in either location – suggesting that phreatophytic S. vermiculatus rangelands near the eastern terminus of their range are resilient to anthropogenic burning. Future research should investigate the use of prescribed fire with other methods such as revegetation and herbicide application for reducing exotic plant dominance and increasing native plant species.

Drought is one of the most important abiotic stresses limiting the survival, growth, and productivity of plants in many regions of the world. This study was conducted to evaluate drought tolerance of the recombinant genotypes of two species of orchardgrass and smooth bromegrass based on clonal evaluation and stress tolerance indices. In this study, 36 genotypes selected from polycross populations of both species of orchardgrass and smooth bromegrass were evaluated in terms of phenological, agronomic and morphological traits under normal (50% water depletion from the root zone depth) and drought-stressed (90% water depletion from the root zone depth) conditions during 2013 to 2015 at the Research Farm of Isfahan University of Technology, Isfahan, Iran. To evaluate drought tolerance of the mentioned genotypes, five drought tolerance and susceptibility indices including stress tolerance indices (TOL and STI), mean productivity index (MP), geometric mean productivity (GMP) and stress sensitivity index (SSI) were calculated based on forage yield under drought stress (Ys) and non- stress (Yp) conditions. In both species, high genetic variation was observed among genotypes in terms of most of the studied traits and indices. In orchardgrass, the genetic coefficient of variation varied from 4.31% to 23.5% under normal condition, and from 1.31% to 21.3% under drought stress condition. In smooth bromegrass, the range of genetic coefficient of variation was variable from 2.05-21.4% under normal condition and 1.66-24.6% under drought stress condition. This indicated a high potential for improving these traits through targeted selection in breeding programs of the two species. Drought stress significantly affected most of the studied traits and reduced the genetic variability of traits except for days to ear emergence, days to pollination, percentage of dry matter yield of cut 1, and percentage of dry matter yield of cut 2 in orchardgrass, and percentage of dry matter yield of cut 1 and percentage of dry matter yield of cut 3 in smooth bromegrass. The amount of this reduction for dry matter yield of cuts 1, 2 and 3 was 47.5, 67.3, and 66.6 percent, respectively, in orchardgrass, and 37.4, 49.5, and 49.4 percent, respectively, in smooth bromegrass. Low heritability for forage yield (24.7, 13.5, and 25.9 percent for dry matter yield of cut 1, dry matter yield of cut 2, and dry matter yield of cut 3, respectively, in orchardgrass, and 59.5, 45.9, and 59.4 percent for dry matter yield of cut 1, dry matter yield of cut 2, and dry matter yield of cut 3, respectively, in smooth bromegrass) suggested that direct selection based on forage yield is not effective for the improvement of this trait. Though, indirect selection based on components of forage yield which have high heritability and high correlation with yield (i.e. plant height, stems/plant, and crown diameter in both species), would be more effective. In both species, selection indices of MP, GMP, and STI had a positive and significant correlation with forage yield (0.92, 0.75, and 0.75, respectively, under normal condition, and 0.61, 0.81, and 0.77, respectively, under drought-stressed condition, in orchardgrass; and 0.95, 0.92, and 0.88, respectively, under normal condition, and 0.91, 0.95, and 0.95, respectivel, under drought-stressed condition, in smooth bromegrass). Therefore, these indices were identified as desirable ones in the selection of drought tolerant cultivars in orchardgrass and smooth bromegrass. Based on the results of principal component analysis and drought tolerance and susceptibility indices, the genotypes of 13 and 14 in orchardgrass, and 13 and 32 in smooth bromegrass were identified as superior genotypes in terms of forage yield and drought tolerance. These genotypes can be used as superior parents for the development of genetic populations to improve forage yield and stress tolerance and create synthetic cultivars.

Drought is one of the most important abiotic stresses limiting the survival, growth, and productivity of plants in many regions of the world. This study was conducted to evaluate drought tolerance of the recombinant genotypes of two species of orchardgrass and smooth bromegrass based on clonal evaluation and stress tolerance indices. In this study, 36 genotypes selected from polycross populations of both species of orchardgrass and smooth bromegrass were evaluated in terms of phenological, agronomic and morphological traits under normal (50% water depletion from the root zone depth) and drought-stressed (90% water depletion from the root zone depth) conditions during 2013 to 2015 at the Research Farm of Isfahan University of Technology, Isfahan, Iran. To evaluate drought tolerance of the mentioned genotypes, five drought tolerance and susceptibility indices including stress tolerance indices (TOL and STI), mean productivity index (MP), geometric mean productivity (GMP) and stress sensitivity index (SSI) were calculated based on forage yield under drought stress (Ys) and non- stress (Yp) conditions. In both species, high genetic variation was observed among genotypes in terms of most of the studied traits and indices. In orchardgrass, the genetic coefficient of variation varied from 4.31% to 23.5% under normal condition, and from 1.31% to 21.3% under drought stress condition. In smooth bromegrass, the range of genetic coefficient of variation was variable from 2.05-21.4% under normal condition and 1.66-24.6% under drought stress condition. This indicated a high potential for improving these traits through targeted selection in breeding programs of the two species. Drought stress significantly affected most of the studied traits and reduced the genetic variability of traits except for days to ear emergence, days to pollination, percentage of dry matter yield of cut 1, and percentage of dry matter yield of cut 2 in orchardgrass, and percentage of dry matter yield of cut 1 and percentage of dry matter yield of cut 3 in smooth bromegrass. The amount of this reduction for dry matter yield of cuts 1, 2 and 3 was 47.5, 67.3, and 66.6 percent, respectively, in orchardgrass, and 37.4, 49.5, and 49.4 percent, respectively, in smooth bromegrass. Low heritability for forage yield (24.7, 13.5, and 25.9 percent for dry matter yield of cut 1, dry matter yield of cut 2, and dry matter yield of cut 3, respectively, in orchardgrass, and 59.5, 45.9, and 59.4 percent for dry matter yield of cut 1, dry matter yield of cut 2, and dry matter yield of cut 3, respectively, in smooth bromegrass) suggested that direct selection based on forage yield is not effective for the improvement of this trait. Though, indirect selection based on components of forage yield which have high heritability and high correlation with yield (i.e. plant height, stems/plant, and crown diameter in both species), would be more effective. In both species, selection indices of MP, GMP, and STI had a positive and significant correlation with forage yield (0.92, 0.75, and 0.75, respectively, under normal condition, and 0.61, 0.81, and 0.77, respectively, under drought-stressed condition, in orchardgrass; and 0.95, 0.92, and 0.88, respectively, under normal condition, and 0.91, 0.95, and 0.95, respectivel, under drought-stressed condition, in smooth bromegrass). Therefore, these indices were identified as desirable ones in the selection of drought tolerant cultivars in orchardgrass and smooth bromegrass. Based on the results of principal component analysis and drought tolerance and susceptibility indices, the genotypes of 13 and 14 in orchardgrass, and 13 and 32 in smooth bromegrass were identified as superior genotypes in terms of forage yield and drought tolerance. These genotypes can be used as superior parents for the development of genetic populations to improve forage yield and stress tolerance and create synthetic cultivars. [ABSTRACT FROM AUTHOR]

Invasive annual grasses can promote ecosystem state changes and habitat loss in the American Southwest. Non-native annual grasses such as Bromus spp. and Schismus spp. have invaded the Mojave Desert and degraded habitat through increased fire occurrence, severity, and shifting plant community composition. Thus, it is important to identify and characterize the areas where persistent invasion has occurred, identifying where subsequent habitat degradation has increased. Previous plot and landscape-scale analyses have revealed anthropogenic and biophysical correlates with the establishment and dominance of invasive annual grasses in the Mojave Desert. However, these studies have been limited in spatial and temporal scales. Here we use Landsat imagery validated using an extensive network of plot data to map persistent and productive populations of invasive annual grass, called hot spots, across the entire Mojave Desert ecoregion over 12 years (2009–2020). We also identify important variables for predicting hot spot distribution using the Random Forest algorithm and identifying the most invaded subregions. We identified hot spots in over 5% of the Mojave Desert mostly on the western and eastern edges of the ecoregion, and invasive grasses were detected in over 90% of the Mojave Desert at least once in that time. Across the entire Mojave Desert, our results indicate that soil texture, aspect, winter precipitation, and elevation are the highest-ranking predictive variables of invasive grass hot spots, while anthropogenic variables contributed the least to the accuracy of the predictive model. The total area covered by hot spots varied significantly among subregions of the Mojave Desert. We found that anthropogenic variables became more important in explaining invasive annual establishment and persistence as spatial scale was reduced to the subregional level. Our findings have important implications for informing where land management actions can prioritize reducing invasive annual persistence and promoting restoration efforts. [ABSTRACT FROM AUTHOR]

Bromus (Poaceae Bromeae) is a forage grass with high adaptability and ecological and economic value. Here, we sequenced Bromus ciliatus, Bromus benekenii, Bromus riparius, and Bromus rubens chloroplast genomes and compared them with four previously described species. The genome sizes of Bromus species ranged from 136,934 bp (Bromus vulgaris) to 137,189 bp (Bromus ciliates, Bromus biebersteinii), with a typical quadripartite structure. The studied species had 129 genes, consisting of 83 protein-coding, 38 tRNA-coding, and 8 rRNA-coding genes. The highest GC content was found in the inverted repeat (IR) region (43.85–44.15%), followed by the large single-copy (LSC) region (36.25–36.65%) and the small single-copy (SSC) region (32.21–32.46%). There were 33 high-frequency codons, with those ending in A/U accounting for 90.91%. A total of 350 simple sequence repeats (SSRs) were identified, with single-nucleotide repeats being the most common (61.43%). A total of 228 forward and 141 palindromic repeats were identified. No reverse or complementary repeats were detected. The sequence identities of all sequences were very similar, especially with respect to the protein-coding and inverted repeat regions. Seven highly variable regions were detected, which could be used for molecular marker development. The constructed phylogenetic tree indicates that Bromus is a monophyletic taxon closely related to Triticum. This comparative analysis of the chloroplast genome of Bromus provides a scientific basis for species identification and phylogenetic studies.

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Native bunchgrass communities dominated by Stipa pulchra are widely distributed in California but share dominance with non‐native annual grasses. Restoration of these grasslands focuses on altering the balance of native to non‐native grasses to favor the former. This study investigated the impact of burning on vegetation recovery. In the first postfire year burning showed a 70% reduction in cover of non‐native annual grasses (Bromus diandrus exhibited the greatest reduction) and minimal impact on S. pulchra recovery. In the following 3 years, S. pulchra recovered to levels comparable to controls, whereas the annual grasses remained below control levels until the fifth year. Also, in response to reduced annual grass cover on burned sites several species of non‐native Erodium increased from 10 to 30% relative cover, however, the low growth form of these forbs presented a less competitive threat to bunchgrasses than the non‐native annual grasses, and by the third postfire year returned to near control levels. The rare native geophyte Brodiaea kinkiensis was present throughout these grasslands and was not inhibited by burning treatments. To document the reliability of these patterns a second prescription burn was conducted on these sites 5 years after the first burn and vegetation recovery followed for the subsequent 4 years. Patterns observed after the first burn were duplicated following the second burn. The cover of S. pulchra varied in response to precipitation, with the 95% credible intervals of precipitation parameters overlapping zero, however, the cover of non‐native grasses varied greatly with precipitation and had similar trajectories in unburned and burned plots. [ABSTRACT FROM AUTHOR]

Bromus picoeuropeanus is a recently described species belonging to a complex genus of grasses. It inhabits stony soils at heights ranging from 1600 to 2200 m in Picos de Europa (Cantabrian Mountains, northern Spain). This species is morphologically very similar to B. erectus, partially sharing its presumed distribution range. We aim to determine the relationship between these species and their altitudinal ranges in Picos de Europa and the Cantabrian Mountains by conducting phylogenetic analyses based on nuclear (ETS and ITS) and chloroplastic (trnL) markers. Phylogenetic trees were inferred by Maximum Likelihood and Bayesian Inference. Haplotype networks were estimated based on the plastid marker. Although the ITS topologies could not generate exclusive clades for these species, the ETS analyses generated highly supported B. picoeuropeanus exclusive clades, which included locations outside its altitudinal putative range. The ETS-ITS and ETS-ITS-trnL topologies generated B. picoeuropeanus exclusive clades, whereas the trnL-based trees and haplotype networks were unable to discriminate B. erectus and B. picoeuropeanus. This evidence suggests that B. picoeuropeanus is a separate species with a larger distribution than previously thought, opening new questions regarding the evolution of B. erectus and other similar species in European mountainous systems. However, more information is needed regarding B. picoeuropeanus susceptibility to temperature rises. [ABSTRACT FROM AUTHOR]

Herbicide-resistant weeds currently challenge sustainable food production in almost all cropping systems in Europe. Herbicide resistance is increasing, and some European countries are among the most affected globally, such as Spain and France. This situation is worsening not only due to herbicide use restrictions but also due to climate change, rendering Mediterranean countries such as Spain particularly susceptible. Therefore, focus should be aimed at preventive measures, which include those not only based on integrated weed management strategies but also based on a very good knowledge of the biology and ecology of each weed species. The main objective of this review is to provide an overview of potential future herbicide-resistant cases that can evolve in the near future in Europe. We use Spain as the case study, as it is the most affected country in Europe and because it is at risk due to global warming. For different resistant cases detailed on a crop basis, adequate prevention and management measures will be provided in order to avoid resistance evolution relative to the sites of action that are most likely to generate resistant biotypes due to expected high selection pressures. [ABSTRACT FROM AUTHOR]

A former lectotype for Bromus cincinnatus Ten. (Poaceae) has been superseded, as it is in serious conflict with the protologue. Another element of the protologue has been designated as the effective lectotype. The new lectotype is identified as coespecific with Bromus intermedius Guss., a Mediterranean species of Bromus L. subg. Bromus. The new combination Helictochloa panormitana (Lojac.) Romero Zarco is proposed for the species originally described as Avena australis Parl., nom. illeg., which is currently known as Helictochloa cincinnata auct. The lectotypes of Avena panormitana Lojac., Avena opulenta Lojac., and Bromus intermedius Guss. are also designated.

Invasive annual grasses pose a severe threat to drylands of the United States by increasing habitat degradation and the occurrence and severity of wildfires, while simultaneously outcompeting native species. Advances in technology and accessibility of small uncrewed aerial vehicles (sUAV) provide the opportunity for small preserve managers to map and monitor plant invasions in critical habitats for rare and endemic plant species. Many remote sensing techniques rely on the invasive plants' different phenological signals to distinguish them from native plants and habitats. However, invasive annual grasses in the western United States have high variability of interannual productivity and may not green up each year. Therefore, our objective was to use an sUAV (quadcopter drone) to map invasive annual grass regardless of phenological stage in critical Mojave Desert habitat. The study locations were White Dome, a small habitat preserve, and Beehive Dome in Washington County UT, USA. These areas are critical habitats for several endangered and threatened plant species and are covered with sensitive biological soil crusts, making on-the-ground measurements destructive. Using imagery collected with an sUAV we created red, green, blue (RGB) orthomosaics and calculated the Visible Atmospherically Resistant Index (VARI) across these areas. We successfully mapped the litter of invasive annual grasses at one of the two sites. At White Dome, we attained 95.2 % and 84.3 % Producer's and User's Accuracy in mapping invasive annual grasses based on the RGB spectral signature of invasive grass litter. At Beehive Dome, the heterogeneous nature of the edaphic and topographical features made it difficult to accurately map (

The aim of the study was to evaluate the effect of grazing Lolium perenne (Lp) and Bromus valdivianus (Bv) on the average daily weight gain (ADG) and nitrogen use efficiency (NUE) of Holstein Friesian heifers. Thirty heifers strip-grazed two pasture treatments (Lp and Bv) under a randomized complete block design (n = 3). Nutrient concentration and pasture intake were determined. Urine samples were taken, and the total volume of urine and microbial growth were estimated. Retained nitrogen (N), N intake, N excreted in feces and urine and the nitrogen use efficiency (NUE) were calculated. Lolium perenne showed greater WSC and ME but lower NDF than Bv, whereas crude and soluble protein were unaffected. There were no effects of species on ADG or feed conversion, and DMI was not affected by grass species, or the synthesis of microbial protein and purine derivatives. Ammonia in the rumen, urinary N and total N excreted were greater for heifers grazing Bv. In conclusion, the consumption of forage species did not alter the ADG or NUE of grazing heifers, but N partitioning was modified for heifers grazing Bv, due to the lower WSC/CP ratio compared with Lp. [ABSTRACT FROM AUTHOR]

Bromus picoeuropeanus is a recently described species belonging to a complex genus of grasses. It inhabits stony soils at heights ranging from 1600 to 2200 m in Picos de Europa (Cantabrian Mountains, northern Spain). This species is morphologically very similar to B. erectus, partially sharing its presumed distribution range. We aim to determine the relationship between these species and their altitudinal ranges in Picos de Europa and the Cantabrian Mountains by conducting phylogenetic analyses based on nuclear (ETS and ITS) and chloroplastic (trnL) markers. Phylogenetic trees were inferred by Maximum Likelihood and Bayesian Inference. Haplotype networks were estimated based on the plastid marker. Although the ITS topologies could not generate exclusive clades for these species, the ETS analyses generated highly supported B. picoeuropeanus exclusive clades, which included locations outside its altitudinal putative range. The ETS-ITS and ETS-ITS-trnL topologies generated B. picoeuropeanus exclusive clades, whereas the trnL-based trees and haplotype networks were unable to discriminate B. erectus and B. picoeuropeanus. This evidence suggests that B. picoeuropeanus is a separate species with a larger distribution than previously thought, opening new questions regarding the evolution of B. erectus and other similar species in European mountainous systems. However, more information is needed regarding B. picoeuropeanus susceptibility to temperature rises.

Woody, evergreen shrublands are the archetypal community in mediterranean‐type ecosystems, and these communities are profoundly changed when they undergo vegetation‐type conversion (VTC) to become annual, herb‐dominated communities. Recently, VTC has occurred throughout southern California chaparral shrublands, likely with changes in important ecosystem functions. The mechanisms that lead to VTC and subsequent changes to ecosystem processes are important to understand as they have regional and global implications for ecosystem services, climate change, land management, and policy. The main drivers of VTC are altered fire regimes, aridity, and anthropogenic disturbance. Some changes to ecosystem function are certain to occur with VTC, but their magnitudes are unclear, whereas other changes are unpredictable. I present two hypotheses: (1) VTC leads to warming that creates a positive feedback promoting additional VTC, and (2) altered nitrogen dynamics create negative feedbacks and promote an alternative stable state in which communities are dominated by herbs. The patterns described for California are mostly relevant to the other mediterranean‐type shrublands of the globe, which are biodiversity hotspots and threatened by VTC. This review examines the extent and causes of VTC, ecosystem effects, and future research priorities. [ABSTRACT FROM AUTHOR]

Herbicide-resistant weeds currently challenge sustainable food production in almost all cropping systems in Europe. Herbicide resistance is increasing, and some European countries are among the most affected globally, such as Spain and France. This situation is worsening not only due to herbicide use restrictions but also due to climate change, rendering Mediterranean countries such as Spain particularly susceptible. Therefore, focus should be aimed at preventive measures, which include those not only based on integrated weed management strategies but also based on a very good knowledge of the biology and ecology of each weed species. The main objective of this review is to provide an overview of potential future herbicide-resistant cases that can evolve in the near future in Europe. We use Spain as the case study, as it is the most affected country in Europe and because it is at risk due to global warming. For different resistant cases detailed on a crop basis, adequate prevention and management measures will be provided in order to avoid resistance evolution relative to the sites of action that are most likely to generate resistant biotypes due to expected high selection pressures.

Japanese brome (Bromus japonicus Thunb.) has been introduced to four continents from its Eurasian origins and has increased during recent decades, particularly in North America. Invasion of this C3 annual grass into rangelands diminishes native plant communities and hinders livestock performance. Control methods have been developed, but have proven short-lived. Japanese brome is positively correlated with plant litter and standing dead material, suggesting management of those components could be important. Objectives for this study were to isolate and quantify the effects of litter and standing dead on Japanese brome utilizing fall defoliation with four different mowing heights (10, 6, 4, or 1 cm) compared to a non-mowed control. Research was conducted on two ecological sites (silty and claypan) with each site consisting of 25 plots (5.5 × 1.6-m). This study was conducted over 4 yr (2013–2017) and fall mowing reduced old dead mass every year except 2016, which followed a severe drought. Spring soil water was not reduced by fall defoliation. Mowing to 1 cm reduced brome biomass by 40% compared to non-mowed plots and brome production was highly dependent on Sep-Oct precipitation. Brome biomass was least in 2015 during a drought and greatest in 2017 following double the median Sep-Oct precipitation. Non-brome biomass was similar across treatments. An 11% reduction in current-year biomass was observed for mowing heights of 10, 6, and 4 cm whereas a 22% reduction was measured for the 1 cm mowing height compared to non-mowed plots. Perennial grass basal cover was similar for 10, 6, and 4 cm mowing heights and greater than that for mowing at 1 cm whereas, no differences were detected between non-mowed plots and any mowing height. Increasing fall defoliation intensity reduced annual bromes while allowing perennial grasses to persist, indicating fall mowing and possibly grazing are viable options for annual brome management.

The aim of the study was to evaluate the effect of grazing Lolium perenne (Lp) and Bromus valdivianus (Bv) on the average daily weight gain (ADG) and nitrogen use efficiency (NUE) of Holstein Friesian heifers. Thirty heifers strip-grazed two pasture treatments (Lp and Bv) under a randomized complete block design (n = 3). Nutrient concentration and pasture intake were determined. Urine samples were taken, and the total volume of urine and microbial growth were estimated. Retained nitrogen (N), N intake, N excreted in feces and urine and the nitrogen use efficiency (NUE) were calculated. Lolium perenne showed greater WSC and ME but lower NDF than Bv, whereas crude and soluble protein were unaffected. There were no effects of species on ADG or feed conversion, and DMI was not affected by grass species, or the synthesis of microbial protein and purine derivatives. Ammonia in the rumen, urinary N and total N excreted were greater for heifers grazing Bv. In conclusion, the consumption of forage species did not alter the ADG or NUE of grazing heifers, but N partitioning was modified for heifers grazing Bv, due to the lower WSC/CP ratio compared with Lp.

Invasion by exotic grasses is degrading dryland ecosystems worldwide and efforts to restore native vegetation in invaded areas have been largely unsuccessful. Control of invasive grasses with herbicide also limits restoration efforts using native seed. In this study, we evaluated two approaches that could allow for the restoration of a native species Pseudoroegneria spicata while reducing an invasive annual grass Bromus tectorum with a herbicide mixture in the sagebrush steppe ecosystem (the United States). We used two methods to protect native seeds from herbicide: activated carbon was applied as a seed coating with the intent of absorbing the herbicide around the seed, and furrows were used to side‐sweep soil sprayed with herbicide away from the planted seed. Our results indicate that imazapic + glyphosate herbicide application had a strong negative effect on the invasive annual grass, reducing B. tectorum cover 91% after 1 year, and 39% after 2 years. Herbicide also had strong negative effects on P. spicata without a carbon‐coating or furrow treatment, reducing seedling emergence 38%, 2‐year plant density 65%, and 2‐year total growth 90%. Both activated carbon seed coatings and furrow treatments limited herbicide effects on P. spicata 2‐year growth, but neither treatment alone mitigated herbicide effects on all life stages. Combining carbon coatings and furrow treatments mitigated harmful herbicide effects on several plant stages (seedling emergence, plant densities, and growth). Our results suggest that combining activated carbon coatings and furrow results in similar establishment of a native perennial as a non‐herbicide seeding and lowers B. tectorum abundance. [ABSTRACT FROM AUTHOR]

Abstract Native saltbush, Atriplex polycarpa, shrub populations are widely diminished and fragmented in the southern San Joaquin Desert of California due to habitat conversion and invasion by exotic annual grasses of mostly Mediterranean origin. The role these grasses play in saltbush population demography is not well understood. We hypothesized that saltbush seedling recruitment and growth is limited by the competitive interactions with exotic grasses, preventing saltbush stands from maintaining their populations and expanding. We predicted that saltbush seedling recruitment would be reduced by (1) light and moisture competition with the grasses; and (2) the physical barrier of grass residual dry matter (RDM) formed during senescence. To test our predictions, we investigated saltbush seedling recruitment under field conditions across six saltbush populations. We examined how variations in edaphic structure and water availability by site may have affected saltbush seedling recruitment and longer‐term population dynamics. In experimental plots where saltbush seeds were sowed, exotic grass RDM reduced saltbush seedling emergence compared to seeds sown in the absence of RDM; competition post‐emergence was not significant. Saltbush seedlings transplanted into the field had lower mortality and less herbivory in invaded grassy habitats compared to seedlings planted in bare zones in between established, mature saltbush shrubs. Edaphic variation and water availability by site were likely key factors affecting the success of both grass invasion and saltbush recruitment. Our results suggest that there is a seed–seedling conflict: Sites favorable for saltbush seedling emergence (minimal grass cover among mature shrubs) are unfavorable for seedling survival due to high herbivory. Conversely, sites favorable for saltbush seedling survival (high grass coverage away from mature shrubs) are unfavorable for seedling emergence. The RDM produced by grasses represents an important stabilizing feedback favoring continued grass dominance.

Native saltbush, Atriplex polycarpa, shrub populations are widely diminished and fragmented in the southern San Joaquin Desert of California due to habitat conversion and invasion by exotic annual grasses of mostly Mediterranean origin. The role these grasses play in saltbush population demography is not well understood. We hypothesized that saltbush seedling recruitment and growth is limited by the competitive interactions with exotic grasses, preventing saltbush stands from maintaining their populations and expanding. We predicted that saltbush seedling recruitment would be reduced by (1) light and moisture competition with the grasses; and (2) the physical barrier of grass residual dry matter (RDM) formed during senescence. To test our predictions, we investigated saltbush seedling recruitment under field conditions across six saltbush populations. We examined how variations in edaphic structure and water availability by site may have affected saltbush seedling recruitment and longer‐term population dynamics. In experimental plots where saltbush seeds were sowed, exotic grass RDM reduced saltbush seedling emergence compared to seeds sown in the absence of RDM; competition post‐emergence was not significant. Saltbush seedlings transplanted into the field had lower mortality and less herbivory in invaded grassy habitats compared to seedlings planted in bare zones in between established, mature saltbush shrubs. Edaphic variation and water availability by site were likely key factors affecting the success of both grass invasion and saltbush recruitment. Our results suggest that there is a seed–seedling conflict: Sites favorable for saltbush seedling emergence (minimal grass cover among mature shrubs) are unfavorable for seedling survival due to high herbivory. Conversely, sites favorable for saltbush seedling survival (high grass coverage away from mature shrubs) are unfavorable for seedling emergence. The RDM produced by grasses represents an important stabilizing feedback favoring continued grass dominance. [ABSTRACT FROM AUTHOR]

Los objetivos de este trabajo fueron evaluar producción forrajera, contenido de proteína, y producción de semilla de líneas experimentales de cebadillas pampeana, criolla e intermedia. Se utilizó como referencia al cultivar Don Lorenzo INTA de cebadilla Intermedia. Se realizaron dos ensayos según un diseño en bloques completos aleatorizados con cuatro repeticiones. En uno se evaluó producción de materia seca y contenido de proteína, y en la otra producción de semilla y peso de mil semillas. Se realizó ANOVA y OMS (p

Karyotypes of five taxa (fourteen populations) of the genus Bromus from different geographic origins is presented: B. scoparius, B. japonicus, B. madritensis, B. rubens and B. tomentellus. The ploidy levels were different. B. scoparius and B. japonicus were found 2n=2x=14, B. madritensis and B. rubens were found 2n=4x=28 and B. tomentellus were found 2n=6x=42. Detailed karyotype analysis allows us to group the different populations and to postulate relationships among them.

BACKGROUND Anisantha and Bromus spp. are widespread and difficult to control, potentially due to the evolution of herbicide resistance. In this study, UK populations of four brome species have been tested for the early development of resistance to acetolactate synthase (ALS)‐inhibiting herbicides commonly used in their control. RESULTS: Glasshouse assays confirmed reduced sensitivity to ALS‐inhibiting herbicides in single populations of A. diandra, B. commutatus and B. secalinus, and in three populations of A. sterilis. By contrast, all 60 brome populations tested were sensitive to the ACCase‐inhibiting herbicide propaquizafop and glyphosate. Dose–response with two ALS herbicides showed broad‐ranging resistance in the A. diandra, A. sterilis and B. commutatus populations. In the B. commutatus population, this was associated with a point mutation in the ALS enzyme conferring target site resistance (TSR). Additionally, resistant populations of A. sterilis and B. commutatus populations contained enhanced amounts of an orthologue of the glutathione transferase phi (F) class 1 (GSTF1) protein, a functional biomarker of nontarget site resistance (NTSR) in Alopecurus myosuroides. There was further evidence of NTSR as these plants also demonstrated an enhanced capacity to detoxify herbicides. CONCLUSION: This study confirms the evolution of resistance to ALS inhibiting herbicides in brome species in the UK by mechanisms consistent with the evolution of both TSR and NTSR. These findings point to the need for increased vigilance in detecting and mitigating against the evolution of herbicide resistance in brome species in Northern Europe. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Hordeum spp. (barley grass) and Bromus spp. (brome grass) are annual weed species that achieve long‐distance seed dispersal via attachment to sheep, but also lead to sheep carcass damage due to the penetration of seeds into animal tissues. Range expansion of invasive weed populations predicted as a consequence of climate change may be associated with an increase in seed contamination incidence globally. An examination of Australian abattoir data (2006–2012), along with recent weed distribution patterns, indicates carcass contamination was associated with rainfall and abundance of key annual grass weeds, primarily Bromus spp. and Hordeum spp., although other factors may play a contributing role. Significant differences in seed contamination in slaughtered sheep were noted between states and regions, with widespread contamination occurring throughout all agro‐ecological zones. Abattoir, sheep age and sex significantly influenced incidence, with contamination highest in adult males. Incidence increased with mean monthly rainfall, but declined with mean elevation, and significant interactions were noted between mean monthly temperature and state, and between mean elevation and year. Results show the need for vigilant recording of seed injuries in sheep to enhance weed surveillance efforts and effective integrated weed management of contributing annual grass weeds. [ABSTRACT FROM AUTHOR]

This study is concerned with the morphological cladistic analysis of monotypic tribe Bromeae including the genus Bromus. To characterize taxonomic circumscription of the genus, its species and sectional relationships of 39 taxa belonging to 6 sections and 2 outgroups were evaluated. Based on the heuristic search for 26 morphologhical informative characters, Maximum Parsimony approach was used for phylogenetic analyses The data matrix was analyzed by reweighting characters method, rescaled consistency index and retention index. The results obviously indicate the monophyly of the genus Bromus and taxonomic circumscription of its sections but phylognetic relationships of many of the species within each section remain unresolved. The monotypic sect. Nevskiella (lemmas short, 3.5-5 mm long and awns 3-5 times the length of lemmas) is clearly separated from other sections of the genus Bromus. Old world taxa of the perennial sect. Pnigma are more closely related to sect. Ceratochloa. The annual sects. Genea (spikelets cuneiform, broader at top) and Bromus (spikelets ovate, elliptic or lanceolate tapering towards top, lemmas with 1-5(6) awns) are monophyletic. The present cladistic analysis confirms the incorporation of the genus Boissiera (lemmas with 7-9 awns) into the genus Bromus.

The genus of Bromus is one of the most important collection of rangeland plants, which are distributed in a wide range of natural areas of Iran. Interspecific relationships were evaluated in 90 accessions of 18 Bromus species based on 15 ISSR and 15 SCoT primers. SCoT markers separated the accessions better than ISSR marker. In addition, there was a high interspecific diversity between surveying germplasm. The sections of Bromus genus completely separated based on DNA molecular markers. SCoT markers could separate the accessions in each species. The primers of SC5 and SC35 from SCoT marker and UBC861, UBC857 and UBC844 primers from ISSR marker were identified as the best primers in revealing of genetic diversity between accessions. The sections of Ceratochloa, Genea, Pnigma and Bromus were monophyletic and were placed in one cluster. The section Bromus had a direct relationship with section Genea. In other words, section Ceratochloa has a direct relationship with Pnigma. B. tectorum and B. sericeus. B. sterilis had the most distance with other species in section Genea. B. squarrosus and B. japonicus had the most similarity and B. briziformis with B. danthoniae and B. scoparius with B. rechingeri had a moderate relationship in section Bromus. B. tomentosus and B. persicus had the highest similarity and B. riparius with B. biebersteinii and B. tomentellus with B. inermis had a moderate similarity in section Pnigma. [ABSTRACT FROM AUTHOR]

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During our nomenclatural revision of the genus Bromus L. (Poaceae) for Flora Iberica, we found that several names were still untypified: nine names in current use or their basionyms and five synonyms. Typifications are still needed since stabilising the names will facilitate their use. We propose lectotypes for Bromus alopecuros Poir., B. contortus Desf. (and the superfluous B. alopecuroides Poir.), B. benekenii (Lange) Trimen, B. intermedius Guss. subsp. divaricatus Bonnier & Layens, B. molliformis J.Lloyd ex Billot, B. lepidus Holmb., B. lepidus f. lasiolepis Holmb., Bromus subg. Stenobromus (Griseb.) Hack. and Bromus sect. Stenobromus Griseb. Neotypes for B. erectus Huds. and B. ramosus Huds. and an epitype for B. intermedius subsp. divaricatus Bonnier & Layens are proposed. In addition, we identify an isoneotype for B. erectus and isolectotypes for B. lepidus and B. lepidus f. lasiolepis. The area inhabited by the typified taxa includes both Africa and Europe. All the selected types are in agreement with the current use of the names and, thus, our selections contribute to stabilising the nomenclature of the genus Bromus. A discussion is provided to justify the selections. In addition, we typified two supraspecific names B. subg. Stenobromus and B. sect. Stenobromus. Finally, a new section, B. sect. Penicillius Llamas & Acedo, is described. [ABSTRACT FROM AUTHOR]

In part, the enemy release hypothesis of plant invasion posits that generalist herbivores in the non-native ranges of invasive plants will prefer native plants to exotic invaders. However, the extent to which this occurs in natural communities is unclear. Here, I examined the foraging preferences of an important guild of generalist herbivores—granivorous rodents—with respect to seeds from a suite of native and invasive Bromus (“brome”) species at five study sites distributed across ≈ 80,000 km2 of the Great Basin Desert, USA. By examining only congeners, I accounted for a potentially large source of interspecific variation (phylogenetic relatedness). In general, granivorous rodents removed seeds from native bromes at a 23% higher rate than seeds from invasive bromes, suggesting a preference for native species. This preference was not entirely explained by seed size, and patterns of seed removal were consistent across study sites. These findings suggest that invasive bromes in the Great Basin might experience less rodent granivory than native congeners, which is consistent with a key prediction derived from the enemy release hypothesis. [ABSTRACT FROM AUTHOR]

The sustainability of Mediterranean agroecosystems is threatened by several factors, soil erosion being the most important one due to poor management practices. Seeding native grasses for ground cover is an effective practice to protect soil and enhance ecosystem services, but the species to be used should be adapted to the climatic conditions and the particular requirements of each system. Here, we studied seed germination timing of six winter annual grasses: Aegilops triuncialis , Anisantha madritensis , Anisantha rubens , Bromus hordeaceus , Hordeum murinum and Trachynia distachya ; with potential for ground cover in olive groves of the Iberian Peninsula. We conducted germination experiments under eight treatments of constant and alternate temperatures and seven treatments of water potential, and fitted hydro- and thermal-time models to assess possible responses of seed-based populations to regional climate. In all species, recently-harvested seeds showed high germination rates across a wide range of temperatures, while winter-stored seeds were highly tolerant to moisture stress. Our results suggest that environmental conditions rather than dormancy prevent germination of the studied species after dispersal. This germination pattern contrasts with the deep physiological dormancy described for winter annuals in temperate climates and desert regions, indicating a special adaptation of the studied populations for the long dry season in Mediterranean climates. We conclude that the regeneration ecology of these widely-distributed grasses makes them an excellent source of seeds for ground cover in Mediterranean woody crops. [ABSTRACT FROM AUTHOR]

Twenty five species from four sections of the genus Bromus were evaluated by means of numerical analyses of characters of flower microstructures (lodicule, lemma, palea). Special development of lodicules (lobe and hairiness) and both glumellae (lemma and palea) similar in grasses evolutionarily close (Bromeae, Brachypodieae, Triticeae) was discovered. For most of the characters the original interspecific and intersectional relations were observed in a space of minimum spanning tree (MST). The evolutionary old section Pnigma occupies the largest space. Species of Pnigma having small chromosomes can be distinguished from those having large ones. The section Ceratochloa is scattered through the smallest space. The above points to the endemic evolution of high polyploids of the section. The sections Bromus and Genea are evolutionarily close and they distinctly overlap each other in the MST space. Bromus sterilis, B. catharticus and B. riparius are extremes in their own sections.

Priority effects are hypothesized to play an important role in community assembly and may promote suppression of native by exotic species. Work in a range of grassland systems has proved valuable for testing these effects, demonstrating that earlier germination by some exotic annual grasses contributes to their competitive dominance over natives. Yet few studies have measured native forb germination phenology under field conditions, and the demographic consequences of emergence timing for competitive interactions and native fitness are not well understood. We focused on three native annual species in a southern California grassland dominated by exotic Bromus spp. over three years, measuring (1) seedling emergence rates, for both early (October) and later (November and December) germinators; (2) effects of exotic grasses on native survival and reproduction, through a grass removal experiment; and (3) interactions between emergence timing and grass competitive effects on native mortality, survival, and flowering. We quantified tradeoffs of emergence timing, by estimating mortality experienced by early germinants until the late cohort emerged (early survival), and then for both cohorts from the time of late emergence to flowering (spring survival). The two most common focal natives, Amsinckia intermedia and Phacelia distans, varied substantially in germination phenology but primarily emerged early. The less abundant Clarkia purpurea germinated late. Late emergence reduced spring survival in control plots but not those where exotic grasses were reduced experimentally, supporting the importance of priority effects and benefits of early germination in competition with grasses. However, early emergence entailed a high cost of initial mortality risk in some years. We found no effect of emergence timing on size at flowering. Estimates of net survivorship to flowering suggest that late emergence consistently was associated with the highest survival when exotic grasses were reduced experimentally. Early emergence was more favored in control than in exotic grass reduction plots, but the survival tradeoffs differed substantially between years. These results suggest that priority effects contribute to suppression of native forbs, but may not consistently promote higher fitness for earlier germinators. Instead, exotic invasion may increase yearly variation in the fitness consequences of native germination phenology, with potential implications for bet hedging strategies. [ABSTRACT FROM AUTHOR]

California sage scrub (CSS), a native ecosystem type of low-elevation areas of Southern California, is increasingly threatened by urban development, altered fire regimes, and vegetation-type conversion to non-native grasslands. Using pitfall traps, we examined how suburbanization, type conversion, and fire influence ground-dwelling spider assemblages in eastern Los Angeles County, CA, by surveying spiders in three habitats (CSS, non-native grasslands, and suburban areas) before and after a fire that occurred in a small portion of our study site. Spider assemblages in the suburban habitat differed from those in CSS and non-native grassland habitats, but CSS and grassland assemblages did not significantly differ. This suggests that the urban development, but not vegetation-type conversion to non-native grasslands, has significant effects on ground-dwelling spider assemblages. Fire had no observable effect on assemblages. Because ground-dwelling spiders were not impacted by fire and type conversion, increased fire frequencies, which often result in the establishment of non-native grasses, may not deleteriously influence this animal group, a differing pattern from other taxonomic groups. However, the rapid urban development occurring in low-elevation areas of Southern California means that species requiring nonsuburban sites for their survival (15 species, 24.1%) may be threatened and require conservation assessment. [ABSTRACT FROM AUTHOR]

Aims: Rytidosperma species are native Australian grasses which have different growth rates and phosphorus (P) requirements. This study examined the role of root morphology traits in response to P supply. Methods: Nine Rytidosperma species ranging from slow- to fast-growth were examined along with Lolium perenne and Bromus hordeaceus. Plants were grown in a glasshouse for 47 days in soil supplied with six levels of P between 0 and 60 mg P per pot. Root mass, length and diameter, root hair length and density, and extent of mycorrhizal colonisation were measured. Results: Across all species there was a positive correlation ( P < 0.001) between P uptake and root mass, length and root hair cylinder volume (RHCV; estimated using root diameter, root hair length and root length) at all levels of P supply. An exception was the RHCV of B. hordeaceus, where expected P uptake was not achieved due to a markedly reduced root length at low-P supply. For the Rytidosperma species, morphological plasticity for specific root length, root mass fraction and root hair length ranged from 1.5-fold to 2.7-fold between high- and low-P supply. However, across all species and P levels no single root morphological trait was identified for universally increasing the size of the root system and P uptake. Conclusions: Fast-growing species took up more P as a result of an overall larger root mass, greater root length and larger RHCV. [ABSTRACT FROM AUTHOR]

Context: Annual grass invasions often increase the frequency and extent of wildfire. Climate variability and fire history may have modifying effects on invasion success and its link to changing fire regimes. Objective: Characterize the role of climate variability and fire history in vegetation shifts of an invaded desert landscape. Method: Pre- and post-fire landscape vegetation greenness were assessed on multiple, independent wildfires in Mojave Desert shrublands using a 34 year record of normalized difference vegetation index (NDVI) derived from 1685 Landsat images and matched with a record of precipitation using linear regression. Results: Annual maximum NDVI, and its annual variance of monthly maximum values, were significantly higher on post-fire than pre-fire landscapes. Additionally, post-fire landscapes showed greater sensitivity to antecedent precipitation received the previous 4 months than pre-fire and unburned landscapes. Ground surveys of vegetation indicate that post-fire landscapes show little indication of recovery of native shrub cover and density but instead are dominated by the exotic grass red brome ( Bromus rubens L.). Increased NDVI sensitivity to precipitation is likely related to the growth of red brome, which dominates burned landscapes. Record precipitation in the fall of 2004 contributed to the record NDVI values in 2005 likely driven by high density of red brome. Conclusions: The heightened response of post-fire vegetation to extreme and more variable precipitation events appears to be contributing to the emergence of an invasive grass-fire cycle that constrains the re-establishment of fire sensitive native shrubs while reinforcing the dominance of exotic grasses. [ABSTRACT FROM AUTHOR]

• Mapping plants in drylands based on phenology can be unpredictable in any given year. • Some soils have distinct contrast with litter that mapping possible without actively photosynthetic tissue. • Utilizing sUAV increases access to measure plant communities and areas with biocrusts that are vulnerable to disturbance. • Early image capture may increase contrast of litter with similar colored soil backgrounds. Invasive annual grasses pose a severe threat to drylands of the United States by increasing habitat degradation and the occurrence and severity of wildfires, while simultaneously outcompeting native species. Advances in technology and accessibility of small uncrewed aerial vehicles (sUAV) provide the opportunity for small preserve managers to map and monitor plant invasions in critical habitats for rare and endemic plant species. Many remote sensing techniques rely on the invasive plants' different phenological signals to distinguish them from native plants and habitats. However, invasive annual grasses in the western United States have high variability of interannual productivity and may not green up each year. Therefore, our objective was to use an sUAV (quadcopter drone) to map invasive annual grass regardless of phenological stage in critical Mojave Desert habitat. The study locations were White Dome, a small habitat preserve, and Beehive Dome in Washington County UT, USA. These areas are critical habitats for several endangered and threatened plant species and are covered with sensitive biological soil crusts, making on-the-ground measurements destructive. Using imagery collected with an sUAV we created red, green, blue (RGB) orthomosaics and calculated the Visible Atmospherically Resistant Index (VARI) across these areas. We successfully mapped the litter of invasive annual grasses at one of the two sites. At White Dome, we attained 95.2 % and 84.3 % Producer's and User's Accuracy in mapping invasive annual grasses based on the RGB spectral signature of invasive grass litter. At Beehive Dome, the heterogeneous nature of the edaphic and topographical features made it difficult to accurately map (<20 %) using VARI and RGB alone. Here, we propose plans to increase accuracy in these dryland systems to be able to map invasive annual grasses regardless of year or environmental conditions. [ABSTRACT FROM AUTHOR]

Scientists are increasingly interested in the evolutionary responses of organisms to unpredictable, variable, and extreme climate changes. In semiarid environments, inter-annual variability in the frequency and amount of rainfall affects both the growth and recruitment of plant species, especially annuals. In these inherently variable environments, individual selection should favor demographic responses that spread the risk of mortality over time and enhance long-term reproductive success (i.e., bet-hedging strategies). However, the same processes that allow the persistence and recruitment of native species could facilitate the introduction and establishment of exotics. We assessed whether native and exotic annuals in semiarid Chile displayed similar or contrasting bet-hedging traits, and discuss mechanisms of coexistence of both types of species and their demographic variation under interannual rainfall variability driven by El Niño Southern Oscillation (ENSO). We analyzed a proxy of long-term fitness, i.e., the variability of seed density over 17 years, for the two most common native and two exotic annual plant species present in the study area. We experimentally tested whether the quality of the maternal environment (soil water supply in a given year) had an extended effect (e.g. the next year) on the proportion of seed germination or on the mean and/or variability of seed size and seed dormancy. Results showed that native and exotic species in this annual plant assemblage displayed contrasting bet-hedging strategies as evolutionary responses to variable rainfall. Although rainfall variability promotes the evolution of bet-hedging strategies, the nature of these strategies varies across species, presumably to minimize competitive exclusion. In semiarid Chile, the success of two exotic ephemerals that are components of a diverse community of native annual species seems to reflect bet-hedging germination strategies that complement rather than compete with those expressed in dominant natives. [ABSTRACT FROM AUTHOR]

Based on morphological analyses of the awns a taxonomic approach to Bromus sect. Bromus is presented. Based on the original publication B. macrostachys var. triaristatus and B. pseudodanthoniae are stated as homotypic synonyms of B. danthoniae. B. turcomanicus and B. danthoniae subsp. rogersii are treated as synonyms of B. danthoniae. Bromus sect. Triniusia as a synonym of Bromus sect. Bromus and the reduction of the genus Boissiera as synonym of Bromus are confirmed. [ABSTRACT FROM AUTHOR]

The current report discusses Bromus diandrus, a new species in the flora of Bulgaria. A concise description of its morphological features with an emphasis on the characters that distinguish it from the already known representatives of Bromus sect. Genea in the country is presented. The newly established locality is characterized floristically and ecologically. The probabilities of the native or alien origin of the studied population are also discussed. [ABSTRACT FROM AUTHOR]

Eudarluca caricis is a common hyperparasite of rusts. A total of 100 cultures were isolated from six Puccinia species or forms growing on 10 species of British grasses at two sites approximately 3 km apart. 82 isolates collected in 2005 were partially sequenced at the ITS locus, and amplified fragment length polymorphism profiles generated for 86 isolates from 2005 and 12 from 2007. Partial ITS sequences of most isolates grouped closely, in a clade with previously reported graminaceous Puccinia isolates and a number of Melampsora isolates. A second clade was very distinct and contained mostly isolates from Puccinia poarum on Poa trivialis . All isolates had distinct AFLP haplotypes. The P. poarum isolates were very distinct from isolates collected from other rusts at the same site. Isolates from P. brachypodii f. sp. arrhenatheri growing on Arrhenatherum elatius in 2005 and 2007 at the same location were distinct (P < 0.001). Isolates from each rust or grass in one year and site were more similar than expected from overall variation between isolates (P < 0.001). Isolates from P. coronata on different grasses clustered together (with isolates from P. brachypodii f. sp. poae-nemoralis ), suggesting partial host rust specialisation in E. caricis . [ABSTRACT FROM AUTHOR]

Competitive ability, the ability to generate legacy effects, and the potential to benefit from priority, individually or interactively, are traits that may increase the invasive potential of plants. In this project we examine these three traits in three invasive species ( Agropyron cristatum, Bromus tectorum, and Taeniatherum caput- medusae). Specifically in this study, we examine competitive effects of these invasive species, the ability of these invasive species to generate legacy effects (as plant-soil feedback), and the potential of these three species benefit from priority (being sown concurrently, 30 days before, and 30 days after the restoration species) in a greenhouse study using field collected soil. Our results suggest that all three invasive species can benefit from priority and all three have high competitive ability. However, only A. cristatum benefited from legacy effects of plant-soil feedback. [ABSTRACT FROM AUTHOR]

Invasive annual grasses alter fire regimes in shrubland ecosystems of the western USA, threatening ecosystem function and fragmenting habitats necessary for shrub-obligate species such as greater sage-grouse. Post-fire stabilization and rehabilitation treatments have been administered to stabilize soils, reduce invasive species spread and restore or establish sustainable ecosystems in which native species are well represented. Long-term effectiveness of these treatments has rarely been evaluated., We studied vegetation at 88 sites where aerial or drill seeding was implemented following fires between 1990 and 2003 in Great Basin ( USA) shrublands. We examined sites on loamy soils that burned only once since 1970 to eliminate confounding effects of recurrent fire and to assess soils most conducive to establishment of seeded species. We evaluated whether seeding provided greater cover of perennial seeded species than burned-unseeded and unburned-unseeded sites, while also accounting for environmental variation., Post-fire seeding of native perennial grasses generally did not increase cover relative to burned-unseeded areas. Native perennial grass cover did, however, increase after drill seeding when competitive non-natives were not included in mixes. Seeding non-native perennial grasses and the shrub Bassia prostrata resulted in more vegetative cover in aerial and drill seeding, with non-native perennial grass cover increasing with annual precipitation. Seeding native shrubs, particularly Artemisia tridentata, did not increase shrub cover or density in burned areas. Cover of undesirable, non-native annual grasses was lower in drill seeded relative to unseeded areas, but only at higher elevations., Synthesis and applications. Management objectives are more likely to be met in high-elevation or precipitation locations where establishment of perennial grasses occurred. On lower and drier sites, management objectives are unlikely to be met with seeding alone. Intensive restoration methods such as invasive plant control and/or repeated sowings after establishment failures due to weather may be required in subsequent years. Managers might consider using native-only seed mixtures when establishment of native perennial grasses is the goal. Post-fire rehabilitation provides a land treatment example where long-term monitoring can inform adaptive management decisions to meet future objectives, particularly in arid landscapes where recovery is slow. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Normal seed germination of native herbaceous species can be reduced by high concentrations of deicer products and their constituent salts. Chloride salts are commonly used during the winter months in temperate climates to remove ice and snow. Although these products greatly improve driving conditions, they can have detrimental effects on the vegetation growing along highways. The purpose of this laboratory study was to determine the impact of a magnesium-based deicer product and a sodium-based deicer product and the major salts they contain on the germination and viability of several species of grasses and forbs native to Colorado and planted in revegetation seedings there. Seeds were placed on blotter paper saturated with either a water control, one of three concentrations of each of the deicing solutions, or one of three concentrations of a pure NaCl or MgCl solution. Increasing concentrations of salt ions generally resulted in delayed and reduced normal seed germination, especially the sodium- and magnesium-based deicer solutions. Germination for most species was lower when seeds were grown in deicer solution compared with germination percent of seeds grown in the pure salt solutions. Some species were more tolerant of one of the salts and deicers. Species with C4 photosynthetic pathway were more tolerant than C3 species of high concentrations of both deicer products. Those species which attained the highest germination percent under moderate or high solution concentrations included blue grama, buffalograss, little bluestem, mountain brome, and slender wheatgrass. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Exotic annual brome invasion has been well studied in western North American rangelands, particularly for Bromus tectorum L. invasion in sagebrush ( Artemisia tridentata) grasslands. We examined both aboveground and belowground properties in native sagebrush grassland and adjacent areas dominated by exotic annual bromes ( B. tectorum L. and Bromus japonicus Thunb.) to better understand the fundamental ecological differences between native and invaded areas. Field sites were located in north central Wyoming, USA, and plots were established in areas that had been historically subject to wildfire and either (1) recolonized by native sagebrush grassland vegetation or (2) invaded by exotic annual bromes. We employed measures of vegetation community structure as well as soil physical, chemical, and microbiological properties. Plots with greater than 20 % exotic annual brome cover had significantly less cover of all native vegetation functional groups resulting in lower richness and evenness than native plots. Invaded plots also had low diversity plant communities that were continuous and uniform across space. Soils beneath invaded plant communities had higher infiltration rates, higher levels of total nitrogen, and a lower C/N ratio than the native soils. Invaded soils also had 90-96 % lower abundance of all soil microbial groups measured by phospholipid fatty acid. We conclude that areas dominated by exotic annual bromes display different aboveground and belowground properties compared to the native community, and these changes possibly include spatial and temporal shifts in soil resources and organic matter processing. [ABSTRACT FROM AUTHOR]

The pathogenicity and identity was studied of a field sample ( PcE) of crown rust fungus Puccinia coronata collected in Hungary on wild couch grass ( Elymus repens) and of a field sample ( Psb) of stripe rust ( P. striiformis) collected in the Netherlands on California brome ( Bromus carinatus). We focused on the analysis of the host susceptibility of cultivated barley ( Hordeum vulgare) to both pathogen samples, in direct comparison with an isolate of P. striiformis f.sp. tritici ( Pst) and P. striiformis f.sp. hordei ( Psh). At the seedling stage 83 % of the barley accessions were susceptible to PcE. At the adult plant stage, cultivated barley was predominantly resistant to this crown rust sample. Morphology, pathogenicity on Hordeum and Bromus and ITS DNA sequence analysis determined that PcE represents a European specimen of P. coronata f.sp. hordei. Sample Psb was pathogenic on 47 % of the cultivated barley at the seedling stage. This is intermediate between the isolates Psh (90 %) and Pst (10 %). Psb and Psh were pathogenic to grasses representing several genera. The host range of the Pst isolate was more narrow. We conclude that Psb is unlikely to represent a genotype of Psh that happened to have colonized B. carinatus, and is likely a distinct form of P. striiformis. [ABSTRACT FROM AUTHOR]