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Non‐native annual grasses are degrading rangelands in the western United States and of vital management importance. Novel management strategies are needed to extend current approaches. The aim of this study was to determine if biofumigation was a viable strategy to manage non‐native annual grasses (cheatgrass, Bromus tectorum and ventenata, Ventenata dubia). We tested the effect of Brassica juncea as ground seed meal, seed meal leachate, mustard straw, mustard straw leachate and cereal straw at increasing rates on the two non‐native species and two native perennial grasses (Idaho fescue, Festuca idahoensis and bluebunch wheatgrass, Pseudoroegneria spicata) in a growth chamber experiment. A solarization split treatment was applied using a clear cover to determine if solarization enhanced the biofumigant effect. We recorded the number of emergent seedlings after a 3‐week growth period, determined the effective dose 50%, and the above‐ and belowground biomass. Emergence was inhibited for all species using ground seed meal and seed meal leachate, with lower rates and higher consistency achieved with ground seed meal. Three species were inhibited using mustard straw leachate (not F. idahoensis). Mustard straw reduced emergence in all species but was not different from cereal straw. Solarization did not enhance the effects of the biofumigant for seed meal or mustard straw; conversely, emergence increased from the seed meal and mustard straw leachates under solarization. Responses in biomass varied across species and treatment. Biofumigation applied as ground seed meal may be a viable option for integrated weed management in rangelands, but field experimentation is necessary. [ABSTRACT FROM AUTHOR]

Re-establishing native plants while controlling invasive species is a challenge for many dryland restoration efforts globally. Invasive plants often create highly competitive environments so controlling them is necessary for effective establishment of native species. In the sagebrush steppe of the United States, invasive annual grasses are commonly controlled with herbicide treatments. However, the same herbicides that control invasive annual grasses also impact the native species being planted. As such, carbon-based seed technologies to protect native seeds from herbicide applications are being trialed. In addition to controlling invasive species, ensuring good seed-to-soil contact is important for effective establishment of native species. In this grow room study, we explored the impact of different seed ameliorations when no herbicide was applied and when herbicide was applied. We selected two native species that are important to the sagebrush steppe for this study—the sub-shrub Krascheninnikovia lanata and the perennial bunchgrass Pseudoroegneria spicata—and used three different seed ameliorations—seed pelleting with local soil alone, local soil plus activated carbon and activated carbon alone—to ensure both greater seed-to-soil contact and protection against herbicides. Shoot and root biomass data were collected eight weeks after planting. We found that when herbicide was not applied, K. lanata had the strongest response to the soil alone amelioration, while P. spicata had the strongest response to the activated carbon alone amelioration. However, when herbicide was applied, K. lanata performed best with the soil plus activated carbon treatments, with an average 1500% increase in biomass, while P. spicata performed best with the activated carbon alone treatments, with an over 4000% increase in biomass, relative to bare seed. The results from our study indicate that there is a positive effect of local soils and activated carbon as seed ameliorations, and further testing in the field is needed to understand how these ameliorations might perform in actual restoration scenarios. [ABSTRACT FROM AUTHOR]

Non‐native annual grasses have invaded western rangelands in the United States, and novel approaches are needed to supplement existing management strategies. The aim of this study was to investigate biofumigation, the use of Brassicaceae products to suppress weeds, as a control for two non‐native annual grasses (cheatgrass, Bromus tectorum and ventenata, Ventenata dubia) and its effects on two dominant native perennial grasses (bluebunch wheatgrass, Pseudoroegneria spicata and Idaho fescue, Festuca idahoensis). We tested the effect of the biofumigant Brassica juncea (brown mustard), applied as seed meal and mulch, on germination metrics of the four grass species in Petri dishes. Germination metrics included emergence and viability, time to cotyledon and radicle emergence and their lengths at 14 days after sowing. Impacts on emergence and viability were assessed using a binomial mixed effects model, while time to cotyledon and radicle emergence and lengths were assessed using linear mixed effects models. Seed meal reduced emergence and viability at lower application rates for V. dubia and F. idahoensis than the other two species. Mulch did not consistently reduce emergence or viability. P. spicata was the least inhibited by the biofumigants. When using seed meal, radicle emergence and length were inhibited in B. tectorum, V. dubia and F. idahoensis and cotyledon emergence and length were inhibited for all. The mulch did not impact these metrics consistently and may not be a viable management tool. The use of seed meal biofumigant to suppress undesired annual grasses in rangelands seems promising, but response is species‐specific. [ABSTRACT FROM AUTHOR]

Re-establishing native plants while controlling invasive species is a challenge for many dryland restoration efforts globally. Invasive plants often create highly competitive environments so controlling them is necessary for effective establishment of native species. In the sagebrush steppe of the United States, invasive annual grasses are commonly controlled with herbicide treatments. However, the same herbicides that control invasive annual grasses also impact the native species being planted. As such, carbon-based seed technologies to protect native seeds from herbicide applications are being trialed. In addition to controlling invasive species, ensuring good seed-to-soil contact is important for effective establishment of native species. In this grow room study, we explored the impact of different seed ameliorations when no herbicide was applied and when herbicide was applied. We selected two native species that are important to the sagebrush steppe for this study—the sub-shrub Krascheninnikovia lanata and the perennial bunchgrass Pseudoroegneria spicata—and used three different seed ameliorations—seed pelleting with local soil alone, local soil plus activated carbon and activated carbon alone—to ensure both greater seed-to-soil contact and protection against herbicides. Shoot and root biomass data were collected eight weeks after planting. We found that when herbicide was not applied, K. lanata had the strongest response to the soil alone amelioration, while P. spicata had the strongest response to the activated carbon alone amelioration. However, when herbicide was applied, K. lanata performed best with the soil plus activated carbon treatments, with an average 1500% increase in biomass, while P. spicata performed best with the activated carbon alone treatments, with an over 4000% increase in biomass, relative to bare seed. The results from our study indicate that there is a positive effect of local soils and activated carbon as seed ameliorations, and further testing in the field is needed to understand how these ameliorations might perform in actual restoration scenarios.

Warming and changing precipitation can alter the performance of native grasses that are essential to grassland ecosystems. Native grasses may respond to changing climate by phenotypic plasticity or lose their current ranges. Establishing plant species from southern, warmer provenances may reduce the likelihood of biodiversity loss and improve restoration success in cool, northern locations that are undergoing warming. We conducted competition trials for Pseudoroegneria spicata (bluebunch wheatgrass), a native grass commonly found in western North American grasslands, to understand the impact of temperature and moisture on plant–plant interactions. We obtained seeds from three locations along a latitudinal gradient in North America, two in British Columbia (BC), Canada, and one in California, USA. We compared the effects of warming, changing water inputs, and competitor provenance on pairwise competitive interactions among Pseudoroegneria spicata plants grown from seeds obtained from the three locations. We quantified interactions using the relative interaction intensity, which has values from −1 (complete competition) to +1 (complete facilitation). Target plants from northern British Columbia, the location with the coldest summer temperature, were generally more competitively suppressed when competing with plants from California, which had the warmest summer temperature and lowest summer precipitation. Competitive suppression of target plants from northern British Columbia and southern British Columbia was more intense when competitor provenance was more geographically distant from target plant provenance. Finally, plants from northern British Columbia and southern British Columbia were more suppressed at higher temperatures, indicating some local adaptation, while plants from California were not affected by competitors, temperature, or water input. Plants grown from seeds obtained from warm and dry locations appear to be more tolerant to competition at higher temperatures, compared to plants from cooler regions. Native plant diversity and restoration success in grasslands subjected to climate change may be preserved or improved by assisted migration of seeds from warm to cooler but warming locations. [ABSTRACT FROM AUTHOR]

Article Highlights Compost increased P. spicata and F. campestris root and shoot biomass on alkaline copper mine tailings. Ash increased tailings pH and bunchgrass shoot uptake of molybdenum. P. spicata and F. campestris are ‘accumulators’ of molybdenum on alkaline copper mine tailings.

Effective native plant materials are critical to restoring the structure and function of extensively modified ecosystems, such as the sagebrush steppe of North America's Intermountain West. The reestablishment of native bunchgrasses, e.g., bluebunch wheatgrass (Pseudoroegneria spicata [Pursh] À. Löve), is the first step for recovery from invasive species and frequent wildfire and towards greater ecosystem resiliency. Effective native plant material exhibits functional traits that confer ecological fitness, phenotypic plasticity that enables adaptation to the local environment, and genetic variation that facilitates rapid evolution to local conditions, i.e., local adaptation. Here we illustrate a multi-disciplinary approach based on genomic selection to develop plant materials that address environmental issues that constrain local populations in altered ecosystems. Based on DNA sequence, genomic selection allows rapid screening of large numbers of seedlings, even for traits expressed only in more mature plants. Plants are genotyped and phenotyped in a training population to develop a genome model for the desired phenotype. Populations with modified phenotypes can be used to identify plant syndromes and test basic hypotheses regarding relationships of traits to adaptation and to one another. The effectiveness of genomic selection in crop and livestock breeding suggests this approach has tremendous potential for improving restoration outcomes for species such as bluebunch wheatgrass. [ABSTRACT FROM AUTHOR]

Understanding the environmental drivers of demographic rates and population dynamics over space and time is critical for anticipating how species will respond to climate change. While the influence of temporal environmental variation and large environmental gradients are well recognized, less is known about how local topography and landscape position influence demography over small spatial scales. Here, we investigate how local landscape position (north‐ vs. south‐facing aspects) influence the demographic rates and population growth of a common bunchgrass in western North America, bluebunch wheatgrass (Pseudoroegneria spicata), using 6 annual censuses measuring growth, survival, and reproductive output. We found notably lower survival on south‐facing slopes, particularly among smaller individuals. In contrast, south‐facing slopes maintained comparatively high reproductive output in most years, measured both as spikes per plant and spikelets per spike. When we combined these data in demographic models, we found that lower survival among small individuals and greater reliance on reproduction mean south‐facing slopes would generally have to maintain higher recruitment for a stable population. Our results highlight the important influence that landscape position and local topography can have in driving population trends. As conditions warm and dry with climate change (north‐faces becoming similar to current south‐facing slope conditions), bluebunch wheatgrass may become more reliant on reproduction to maintain viable populations and more sensitive to variability in recruitment. [ABSTRACT FROM AUTHOR]

With many degraded environments undergoing restoration efforts, there is a growing need for the optimization of direct seeding practices. Seeds planted on wildlands are often consumed by rodents, leading to reduced plant establishment. Coating seeds in rodent aversive products may prevent seed‐predation. We tested 10 seed‐coating formulations containing products expected to deter rodents, namely: ghost and cayenne pepper powders; essential oils from bergamot, neem, and pine; methyl‐nonyl‐ketone, anthraquinone, activated carbon, beta‐cyclodextrin, and a blank coating containing no rodent deterrents to serve as a control treatment. Each treatment was applied to Pseudoroegneria spicata (bluebunch wheatgrass) seeds. These seeds germinated similarly to uncoated control seeds unless the coating contained methyl‐nonyl‐ketone which reduced germination. When seeds were offered to Ord's kangaroo rats (Dipodomys ordii), they strongly avoided the treatments in favor of uncoated control seeds. Notably, the blank coating, lacking active ingredients, still elicited 99% avoidance. However, these results indicated behavior when alternative food sources are readily available, a scenario rare in nature. To address this, a second feeding experiment was conducted to observe D. ordii's behavior under calorie‐restricted conditions. D. ordii were subjected to a fast period, then offered only one treatment. Under these conditions, many subjects chose to consume coated seeds, but to a lesser degree than subjects offered control seeds. Seeds coated in ghost pepper, neem oil, and activated carbon reduced consumption by 47–50%. Given these lab results, we would expect these treatments to increase native plant establishment following the direct seeding of wildlands by protecting seeds from rodent predation. [ABSTRACT FROM AUTHOR]

A species' population structure and history are critical pieces of information that can help guide the use of available native plant materials in restoration treatments and decide what new native plant materials should be developed to meet future restoration needs. In the western United States, Pseudoroegneria spicata (bluebunch wheatgrass; Poaceae) is an important component of grassland and shrubland plant communities and commonly used for restoration due to its drought resistance and competitiveness with exotic weeds. We used next‐generation sequencing data to investigate the processes that shaped P. spicata's geographic pattern of genetic variation across the Intermountain West. Pseudoroegneria spicata's genetic diversity is partitioned into populations that likely differentiated since the Last Glacial Maximum. Adjacent populations display varying magnitudes of historical gene flow, with migration rates ranging from multiple migrants per generation to multiple generations per migrant. When considering the commercial germplasm sources available for restoration, genetic identities remain representative of the wildland localities from which germplasm sources were originally developed, and they maintain high levels of heterozygosity and nucleotide diversity. However, the commercial germplasm sources represent a small fraction of the overall genetic diversity of P. spicata in the Intermountain West. Given the low migration rates and long divergence times between some pairs of P. spicata populations, using commercial germplasm sources could facilitate undesirable restoration outcomes when used in certain geographic areas, even if the environment in which the commercial materials thrive is similar to that of the restoration site. As such, population structure and history can be used to provide guidance on what geographic areas may need additional native plant materials so that restoration efforts support species and community resilience and improve outcomes. [ABSTRACT FROM AUTHOR]

Abstract: Question: How does type of disturbance alter plant community composition when an invasive species with high intrinsic population growth rate is present? The sagebrush steppe is a cold semi‐arid steppe dominated by the native shrub Artemisia tridentata Nutt., native bunchgrasses, and has been invaded by the non‐native winter annual Bromus tectorum L. Location: Sagebrush steppe, Montana, USA. Methods: We assessed the effect of fire and soil disturbance, due to bulldozing to create a firebreak, on the resilience of plant communities and their resistance to invasion by B. tectorum. Plant species richness and species composition were monitored for 3 years at two sites post‐fire and firebreak construction. Results: Burned plant communities were resilient and had similar native grass cover and native species richness compared with the unburned sites after 3 years. Soil disturbance from firebreak construction resulted in species composition that was distinct and had lower native grass cover. Type of disturbance also affected the community's resistance to B. tectorum. Bromus tectorum cover was similar in burned and unburned areas, but increased up to three times and remained high where soil disturbance occurred, suggesting a shift to an alternative state. Conclusion: In this northern portion of the sagebrush steppe, communities with native plant cover were resilient to fire but not soil disturbance, which facilitated B. tectorum increase and a transition to an alternative state. In areas of high native plant cover, management tactics should avoid soil disturbance. [ABSTRACT FROM AUTHOR]

Abstract: Invasive species may alter selective pressures on native plant populations. Although there is some evidence that competition with invasive plants may lead to differences in competitive ability between populations that have experienced invasion and those that have not, previous results have varied among species but also among populations of the same species. We conducted a glasshouse experiment to determine whether there was variation in traits or in ability to tolerate or suppress an invasive species among populations of a common native grass that had different histories of exposure to competition from an invasive species. Specifically, we grew seeds of a native grass (Pseudoroegneria spicata) collected from 14 wild populations (six from invaded populations and eight from uninvaded populations) and a cultivar (Anatone) alone or in competition with the invasive aster (Centaurea stoebe) and measured traits of both species during and at the end of a 100‐day growing period. Pseudoroegneria spicata seedlings from invader‐experienced populations had more leaves than invader‐naïve populations, and juvenile plants from experienced populations were less affected by competition with C. stoebe than were plants from naïve populations. There were significant differences in traits among populations at the seedling and juvenile life stages, and at both life stages variation among populations was greater than variation among experience types. The most predictive traits of P. spicata tolerance to competition were number of leaves (seedling and juvenile stage) and total and root biomass (juvenile only). No traits significantly predicted suppression of C. stoebe. There was not a significant relationship between a population's suppression of C. stoebe and its tolerance of competition. Our results suggest that, in P. spicata, invasion selects for larger plants and traits that can influence tolerance of competition. If land managers are interested in identifying highly competitive seed sources for revegetation in invaded areas, both population and invader experience type should be considered. As tolerance and suppression do not appear to be related in P. spicata, seed source selection should be driven by the element of competitive ability (either tolerance or suppression) that is most important to project goals. A plain language summary is available for this article. [ABSTRACT FROM AUTHOR]

While there has been extensive interest in how intraspecific trait variation affects ecological processes, outcomes are highly variable even when individuals are identical: some are lucky, while others are not. Trait variation is therefore important only if it adds substantially to the variability produced by luck. We ask when trait variation has a substantial effect on variability in lifetime reproductive success (LRS), using two approaches: (1) we partition the variation in LRS into contributions from luck and trait variation and (2) we ask what can be inferred about an individual's traits and with what certainty, given their observed LRS. In theoretical stage- and size-structured models and two empirical case studies, we find that luck usually dominates the variance of LRS. Even when individuals differ substantially in ways that affect expected LRS, unless the effects of luck are substantially reduced (e.g., low variability in reproductive life span or annual fecundity), most variance in lifetime outcomes is due to luck, implying that departures from "null" models omitting trait variation will be hard to detect. Luck also obscures the relationship between realized LRS and individual traits. While trait variation may influence the fate of populations, luck often governs the lives of individuals. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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 zero-tension 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 soil-water content, and elevated NO 3 –N 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 CO 2 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. [ABSTRACT FROM AUTHOR]

Many species are characterized by high levels of intraspecific or ecotypic diversity, yet we know little about how diversity within species influences ecosystem processes. Using a common garden experiment, we studied how intraspecific diversity within the widespread and often dominant North American native Pseudoroegneria spicata (Pursh) Á. Löve. affected invasion by Centaurea stoebe L. We experimentally manipulated Pseudoroegneria intraspecific diversity by changing the number of Pseudoroegneria ecotypes in common garden plots, using ecotypes collected throughout western North America. Invader biomass was 46% lower in mono-ecotype Pseudoroegneria plots than in control plots without any plants prior to invasion, and plots with 3-12 Pseudoroegneria ecotypes were 44% less invaded by Centaurea than the mono-ecotype plots. Across all plots, the total biomass of invading Centaurea plants was negatively correlated with total Pseudoroegneria biomass, but biotic resistance provided by high ecotypic diversity of Pseudoroegneria was not explained only by the increase in productivity that occurred with ecotypic diversity. Relative to Pseudoroegneria yield, Centaurea yield was lowest when Pseudoroegneria overyielded due to size-independent 'complementarity' effects. This was not observed when overyielding was due to size-dependent effects. Our results suggest that the intraspecific diversity of a widespread and dominant species has the potential to impact invasion outcomes beyond its effects on native plant productivity and that mechanisms of biotic resistance to invaders may be to some degree independent of plant size. [ABSTRACT FROM AUTHOR]

Restoration practitioners balance the desire to use locally adapted plant materials with the uncertainty of what constitutes 'local.' Provisional seed transfer zones are intended to guide managers on how far plant materials can be moved during revegetation with the assumption that all populations within a zone will show similarly adapted traits. There are multiple approaches to developing provisional transfer zones, including limiting transfer to specific populations, within ecoregions, within climatic zones, or within climatic zones within ecoregion; there is little information about which of these approaches is best or whether the best approach could vary by region. We used Pseudoroegneria spicata as a test species to assess (1) whether EPA Level III Ecoregion or population explained more variation in traits, and (2) which of four common provisional seed transfer zones (Ecoregion-only, Climate-only, USFS seed transfer zone, and Climate in Ecoregion) best explains trait variation. Plants from 14 populations and three ecoregions were grown in a common garden for two years; growth traits, final biomass, seed set, and mortality were measured. Ecoregion explained more variation than population for most growth traits and mortality; population explained more variation only for seed set. Only one of the three ecoregions showed strong trait differentiation. Out of the four provisional seed transfer zone models compared, we found the most support for models containing climate (Climate-only and Climate in Ecoregion). Findings suggest that Level III Ecoregions may be too broad for seed transfer and that managers should consider climate within ecoregion when making seed transfer decisions. [ABSTRACT FROM AUTHOR]

The use of local, native plant materials is now common in restoration but testing for polyploidy in seed sources is not. Diversity in cytotypes across a landscape can pose special seed transfer challenges, because the methods used to determine genetically appropriate materials for seed transfer do not account for cytotypic variation. This lack of consideration may result in mixing cytotypes through revegetation, which could reduce long-term population viability. We surveyed nine populations of a native bunchgrass, Pseudoroegneria spicata, in three EPA Level III Ecoregions in the western United States to determine the frequency of polyploidy, whether there are differences in traits (phenotype, fecundity, and mortality) among plants of different cytotypes, and whether cytotype frequency varies among ecoregions. We assessed trait variation over 2 years in a common garden and determined ploidy using flow cytometry. Polyploidy and mixed cytotype populations were common, and polyploids occurred in all ecoregions. Four of the nine populations were diploid. The other five had tetraploids present: three had only tetraploid individuals whereas two had mixed diploid/tetraploid cytotypes. There was significant variation in traits among cytotypes: plants from tetraploid populations were larger than diploid or mixed populations. The frequency and distribution of cytotypes make it likely that seed transfer in the study area will inadvertently mix diploid and polyploid cytotypes in this species. The increasing availability of flow cytometry may allow ploidy to be incorporated into native plant materials sourcing and seed transfer. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Columbia Germplasm of bluebunch wheatgrass (Pseudoroegneria spicata (Pursh) Á. Löve [Poaceae]) was released by USDA Agricultural Research Service in 2015. It was developed through 5 cycles of selection, primarily for increased numbers of spikes, from K68, a population collected in 1980 in Adams County in eastern Washington. The collection site of K68 averages approximately 250 mm of annual precipitation, about half of the average annual precipitation at the collection sites of 'Whitmar,' 'Goldar,' and Anatone Germplasm, also in eastern Washington. Columbia Germplasm was compared with other bluebunch wheatgrass plant materials at one Nevada, 2 Idaho, and 3 Utah sites in a total of 9 trials, 5 of which were outplanted and 4 of which were seeded. Columbia Germplasm is expected to be of use most widely on Intermountain rangelands that receive between 250 and 350 mm of average annual precipitation. [ABSTRACT FROM AUTHOR]

Plant diversity enhances many ecosystem processes, including productivity, but these effects have been studied almost exclusively at the taxonomic scale of species. We explore the effect of intraspecific diversity on the productivity of a widespread and dominant grassland species using accessions collected from populations throughout its range. We found that increasing population/ecotype diversity of Pseudoroegneria spicata increased productivity to a similar degree as that reported for species diversity. However, we did not find evidence that overyielding was related to either resource depletion or to pathogenic soil fungi, two causes of overyielding in species-diverse communities. Instead, larger accessions overyielded at low diversity at the expense of smaller accessions, and small accessions overyielded through complementarity at all levels of diversity. Furthermore, overyielding was stronger for accessions from mesic environments, suggesting that local adaptation might predictably influence how plants respond to increases in diversity. This suggests that mass-based competition or other cryptic accession-specific processes had complex but important effects on overyielding. Our results indicate that the effects of diversity within a species can be substantial but that overyielding by intraspecifically diverse populations may not be through the same processes thought to cause overyielding in species diverse communities. [ABSTRACT FROM AUTHOR]

Changes in the quantity and quality of plant litter occur in many ecosystems as they are invaded by exotic species, which impact soil nutrient cycling and plant community composition. Such changes in sagebrush-steppe communities are occurring with invasion of annual grasses (AG) into a perennial grass (PG) dominated system. We conducted a 5-year litter manipulation study located in the northern Great Basin, USA. Springtime litter was partially or completely removed in three communities with differing levels of invasion (invaded, mixed, and native) to determine how litter removal and litter biomass affected plant-available soil N and plant community composition. Litter biomass (prior to the removal treatment) was negatively correlated with plant-available N in the invaded community, but was positively correlated in the native community. Plant-available N had greater intra- and inter-annual fluctuations in the invaded compared to the mixed or native communities, but was not generally affected by removal treatments. Litter removal had negative effects on AG cover during a warm/dry year and negative effects on PG cover during a cool/wet year in the mixed community. Overall, the effectiveness of springtime litter manipulations on plant-available N were limited and weather dependent, and only removal treatments >75 % had effects on the plant community. Our study demonstrates how communities invaded by AGs have significantly increased temporal variability in nutrient cycling, which may decrease ecosystem stability. Further, we found that the ecological impacts from litter manipulation on sagebrush communities were dependent on the extent of AG invasion, the timing of removal, and seasonal precipitation. [ABSTRACT FROM AUTHOR]

A genecological approach was used to explore genetic variation in adaptive traits in Pseudoroegneria spicata, a key restoration grass, in the intermountain western United States. Common garden experiments were established at three contrasting sites with seedlings from two maternal parents from each of 114 populations along with five commercial releases commonly used in restoration. Traits associated with size, flowering phenology, and leaf width varied considerably among populations and were moderately correlated with the climates of the seed sources. Pseudoroegneria spicata populations from warm, arid source environments were smaller with earlier phenology and had relatively narrow leaves than those from mild climates with cool summers, warm winters, low seasonal temperature differentials, high precipitation, and low aridity. Later phenology was generally associated with populations from colder climates. Releases were larger and more fecund than most of the native ecotypes, but were similar to native populations near their source of origin. Differences among native populations associated with source climates that are logical for survival, growth, and reproduction indicate that genetic variation across the landscape is adaptive and should be considered during restoration. Results were used to delineate seed transfer zones and population movement guidelines to ensure adapted plant materials for restoration activities. [ABSTRACT FROM AUTHOR]

Although domestic cattle and mule deer ( Odocoileus hemionus) share bluebunch wheatgrass ( Pseudoroegneria spicata) communities throughout western United States and Canada, no study has yet evaluated the effects of cattle grazing on the nutrient intake of mule deer and the nutritional carrying capacity in these semi-arid rangelands. We expected that spring cattle grazing would decrease plant biomass available to deer but increase the nutritional quality of forage by arresting the phenology of grasses, reducing the proportion of standing dead biomass of grasses and promoting forbs. Using 0.4-ha exclosures, we created 3 replicates of paired grazed and non-grazed treatments within 3 pastures ranging from 64 to 509 ha in bluebunch wheatgrass communities on dry-stony ecological sites in southeastern Washington, USA. After cattle had grazed 1 of each pair of 0.4-ha plots to 40% utilization from 10 April to 29 May 2009, we sampled the biomass and measured the digestible energy (DE; kJ/g) and digestible protein (g/100 g feed) of plants that spring and fall. Using hand-raised, tractable mule deer, bite count methods, and behavioral observations, we measured daily DE and digestible protein intake within each plot. When compared to non-grazed plots, grazed plots had half the total and 3 times less live plant biomass in spring, and 25% less biomass in fall, whereas DE content of bluebunch wheatgrass and mule deer diets did not differ between grazing treatments. However, daily DE intake of deer was 39% less in spring and 13% less in fall in grazed than non-grazed plots. Nutritional carrying capacity (deer days/ha) did not vary between grazing treatments except for 1 pasture in fall, indicating that spring grazing by cattle in bluebunch wheatgrass communities did not improve the nutritional quality of deer diets enough to offset the overall loss of live forage biomass. © 2013 The Wildlife Society. [ABSTRACT FROM AUTHOR]

The intentional introduction of specialist insect herbivores for biological control of exotic weeds provides ideal but understudied systems for evaluating important ecological concepts related to top-down control, plant compensatory responses, indirect effects, and the influence of environmental context on these processes. Centaurea stoebe (spotted knapweed) is a notorious rangeland weed that exhibited regional declines in the early 2000s, attributed to drought by some and to successful biocontrol by others. We initiated an experiment to quantify the effects of the biocontrol agent, Cyphocleonus achates, on Ce. stoebe and its interaction with a dominant native grass competitor, Pseudoroegneria spicata, under contrasting precipitation conditions. Plots containing monocultures of each plant species or equal mixtures of the two received factorial combinations of Cy. achates herbivory (exclusion or addition) and precipitation (May-June drought or "normal," defined by the 50-year average) for three years. Cy. achates herbivory reduced survival of adult Ce. stoebe plants by 9% overall, but this effect was stronger under normal precipitation compared to drought conditions, and stronger in mixed-species plots compared to monocultures. Herbivory had no effect on Ce. stoebe per capita seed production or on recruitment of seedlings or juveniles. In normal-precipitation plots of mixed composition, greater adult mortality due to Cy. achates herbivory resulted in increased recruitment of new adult Ce. stoebe. Due to this compensatory response to adult mortality, final Ce. stoebe densities did not differ between herbivory treatments regardless of context. Experimental drought reduced adult Ce. stoebe survival in mixed-species plots but did not impede recruitment of new adults or reduce final Ce. stoebe densities, perhaps due to the limited duration of the treatment. Ce. stoebe strongly depressed P. spicata reproduction and recruitment, but these impacts were not substantively alleviated by herbivory on Ce. stoebe. Population-level compensation by dominant plants may be an important factor inhibiting top-down effects in herbivore-driven and predator-driven cascades. [ABSTRACT FROM AUTHOR]

Abstract: Throughout the western United States, the invasive annual grass, medusahead (Taeniatherum caput-medusae L. Nevski), is rapidly invading grasslands once dominated by native perennial grasses, such as bluebunch wheatgrass (Pseudoroegneria spicata (Pursh) A). It is also invading grasslands dominated by less undesirable invasive annual grasses, especially cheatgrass (Bromus tectorum L.). Understanding medusahead growth dynamics relative to native perennial grasses and cheatgrass is central to predicting and managing medusahead invasion. We hypothesized that medusahead would have a higher relative growth rate (RGR), a longer period of growth, and as a consequence, more total biomass at the end of the growing season than the native perennial grass and cheatgrass. In 2008 (dry conditions), 250 seeds and in 2009 (wet conditions), 250 and 100 seeds of each species were sown in 1 m2 plots with 5 replicates. Shoots were harvested on 3–25 day intervals throughout the growing season. The native perennial grass had more biomass and higher RGR than medusahead in the dry year, but the relationship was reversed in the wet year. Precipitation in 2008 was well-below average and this level of drought is very infrequent based on historical weather data. Medusahead had a longer period of growth and more total biomass than cheatgrass for both years. We expect that medusahead will continue to invade both native perennial and less undesirable invasive annual grasslands because of its higher RGR and extended period of growth. [ABSTRACT FROM AUTHOR]

Climate change could alter the population growth of dominant species, leading to profound effects on community structure and ecosystem dynamics. Understanding the links between historical variation in climate and population vital rates (survival, growth, recruitment) is one way to predict the impact of future climate change. Using a unique, long-term data set from eastern Idaho, USA, we parameterized integral projection models (lPMs) for Pseudoroegneria spicata, Hesperostipa comala, and Artemisia tripartita to identify the demographic rates and climate variables most important for population growth. We described survival, growth, and recruitment as a function of genet size using mixed-effect regression models that incorporated climate variables. Elasticites for the survival + growth portion of the kernel were larger than the recruitment portion for all three species, with survival + growth accounting for 87-95% of the total elasticity. The genet sizes with the highest elasticity values in each species were very close to the genet size threshold where survival approached 100%. We found strong effects of climate on the population growth rate of two of our three species. In H. comata, a 1% decrease in previous year's precipitation would lead to a 0.6% decrease in population growth. In A. tripartita, a 1% increase in summer temperature would result in a 1.3% increase in population growth. In both H. comata and A. tripartita, climate influenced population growth by affecting genet growth more than survival or recruitment. Late-winter snow was the most important climate variable for P. spicata, but its effect on population growth was smaller than the climate effects we found in H. comata or A. tripartita. For all three species, demographic responses lagged climate by at least one year. Our analysis indicates that understanding climate effects on genet growth may be crucial for anticipating future changes in the structure and function of sagebrush steppe vegetation. [ABSTRACT FROM AUTHOR]

Abstract: Cheatgrass (Bromus tectorum L.) has come to dominate millions of hectares of rangeland in the Intermountain western United States. Previous studies have hypothesized that one mechanism conferring a competitive advantage to this species is the ability to germinate rapidly at low temperatures in the fall, winter and spring and, therefore, initiate growth and establishment more rapidly than more desirable perennial bunchgrass species. In this experiment, we developed thermal-germination-response models for multiple seedlots of cheatgrass and five perennial grass species. We conducted sensitivity analysis on potential-cumulative-germination response to a 38-year simulation of field-variable conditions of seedbed temperature and moisture. Cheatgrass uniformly germinated at a higher rate, and required significantly less time to complete germination than any of the perennial species for all but the slowest seed subpopulations. A germination-rate-sum index was used to integrate relative response characteristics over time. This index showed that germination rate of the most rapidly germinating subpopulations of cheatgrass was 2–5 times higher than for the other species tested. Model simulations of this type provide a more ecologically relevant basis for seedlot evaluation as they allow comparisons across a wide range of potential conditions that may be experienced in the field. [Copyright &y& Elsevier]