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Postfire livestock grazing management in the higher-elevation, mesic portions of the sagebrush steppe lacks a firm scientific foundation to support decision making. Following a prescribed fire conducted in fall 2002, we evaluated effects of different lengths of rest from mid-summer (July) cattle grazing on postfire ground cover and plant species diversity responses in mesic sagebrush steppe. Treatment levels representing no rest; 1, 2, or 3 years of rest from grazing, and a burned-ungrazed control, all had similar effects on graminoid and forb basal cover and plant species density and frequency. However, grazing reduced litter cover and increased bare ground exposure relative to the control. A synthesis of this and other case studies of postfire grazing in sagebrush steppe indicates multiple years of rest from grazing are not strictly necessary for effective and timely recovery of vegetation but, on sloping terrain where potential runoff and erosion hazards exist, multiple years of rest may be needed to promote sufficient rates of litter recovery and reduction of bare ground exposure. These findings support calls for increased flexibility in policies governing postfire grazing management on federal lands and, as such, could influence ecosystem health, livestock production and other services throughout much of the western US. [ABSTRACT FROM AUTHOR]

High disturbance frequency, low water availability, and advantageous growth mechanisms of invasive annual compared to native perennial grasses reduce native grass establishment throughout arid rangelands. Modifying seeding dispersal processes, including seeding rate and time, may increase native grass recruitment by influencing safe site occupation. A better understanding of seedling development through life history stages and the ecological processes occurring during these stages may be necessary to comprehend modified dispersal dynamics on plant community assembly. We tested the effects of spring vs. fall annual grass seeding times, adding water, and varying annual and perennial grass propagule pressure on perennial and annual grass recruitment in an eastern Oregon shrub-steppe ecosystem. Across species, survival rates were lowest between germination and emergence stages. However, perennial grass germination rates were highest when perennials were seeded with annual grasses in autumn. Perennial grass recruitment was generally low, especially when annual grass propagule pressure was higher than 150 seeds m −2 . Although, by the second growing season, perennial grasses had the highest density when perennials were seeded with annuals in autumn and water was added. Consequently, modifying native perennial grass dispersal, like priority autumn seeding and increasing propagule pressure, should produce higher perennial grass recruitment across arid lands. [ABSTRACT FROM AUTHOR]

In arid and semi-arid ecosystems vegetation is often arranged in high-density patches imbedded in an extensive matrix dominated by bare soil. This study explores the importance of vegetation pattern in the relationship between grasses and arbuscular mycorrhizal fungi (AMF). In shrub-dominated and bare-soil dominated patches of the Patagonian steppe, we quantified AMF colonization in the dominant grasses Bromus pictus , Poa ligularis , Pappostipa speciosa and Pappostipa humilis . Additionally, in the shrub-dominated patches, AMF colonization was measured in roots under the shrub canopy and off the shrub canopy. Soils in each patch type were also characterized. B. pictus showed the highest AMF colonization, followed by P. speciosa, P. humilis and P. ligularis . The shrub patch resulted to be a fertility hotspot for biological activity and soil attributes. Grass plants in the shrub patches showed in general the highest rates of AMF colonization. Conversely, we did not find consistent differences between the two types of microsites within the shrub patch. Shrub patches may be functioning as refuges for biological activity that preserve the occurrence of mycorrhizal symbiosis of grass species and alter nutrient dynamics. [ABSTRACT FROM AUTHOR]

Climate is a major driver of ecosystem dynamics. In recent years there has been considerable interest in future climate change and potential impacts on ecosystems and management options. In this paper, we analyzed minimum monthly temperature (T min ) for ten rural locations in the western U.S. sagebrush steppe. Oregon and Nevada each had five locations, and the period of record ranged from 69 to 125 years. We used structural time series analysis to evaluate trends over time at each location. We also used box plots to compare variation within months at each location. We concluded: 1) T min variation over years is much higher during the winter than during other seasons, 2) there is evidence of decadal trends in both directions (hotter and cooler) for most, but not all sites, and 3) sites exhibited individualistic patterns rather than following a general regional pattern. The analysis shows that sites in relatively close proximity can exhibit different temperature patterns over time. We suggest that ecologists and land managers make use of any available weather data from local weather stations when planning for the future or interpreting past changes in plant and animal populations, rather than relying on regional averages. [ABSTRACT FROM AUTHOR]

Biomass and species richness are two important indicators of ecosystem stability. The relationship between biomass and species richness along precipitation gradient in semi-arid regions is significant for prediction of ecosystem stability under the estimated climatic drying in the future. In this study, we investigated species richness, aboveground biomass and cover of temperate steppe along a mean annual precipitation (MAP) gradient in central Inner Mongolian of China. We also measured water use efficiency (WUE) of selected species and overall communities. Our results showed that biomass almost remained unchanged in the moist half of the gradient, but species richness decreased markedly with decreasing MAP. Species richness further showed a negligible decrease, whereas a much sharper drop was detected in biomass towards the arid end with decreasing MAP. Vegetation cover shared a similar pattern with biomass and dropped sharply towards the arid end, which may create a strong light and low competition environment favoring C 4 plants. The increment of C 4 species richness could prevent a more intensive decline of species richness under severe arid conditions by raising overall community water use efficiency. Thus, plant communities experiencing water deficiency could also maintain species richness with the occurrence of C 4 plants. [ABSTRACT FROM AUTHOR]

The influence of fire-grazing interactions on ecological pattern and process has been fairly well studied in some rangeland ecosystems (e.g., tallgrass prairie) but is only poorly understood in others. On sagebrush-steppe rangelands of the western US, there has been a long-standing concern that fire followed by grazing can cause substantial mortality in sensitive plant species. Vegetation responses to fire-grazing interactions, however, have never been studied in the higher elevation, more mesic portions of the sagebrush-steppe. We investigated whether graminoid, forb, and litter cover; bare ground; and species density and frequency responses differed among burned areas which were grazed at a very light stocking rate (33 ha AUM −1 ) during spring (May) without postfire deferment, burned areas where 1–2 growing seasons of grazing deferment were applied, and burned areas completely excluded from postfire grazing. Fire-grazing interactions had very few effects on vegetation but did reduce litter cover and bare ground compared to burning alone. This was a case study; consequently, caution should be taken in applying these results beyond their limited scope of inference. In some situations, however, postfire grazing can likely be employed without deferment or after deferring for only one growing season, and not cause substantial adverse impacts on vegetation. [ABSTRACT FROM AUTHOR]

The role of fire in shaping plant traits in crown fire ecosystems is well understood, but little attention has been given to surface fire ecosystems. We studied the effect of fire-related cues (heat shock and smoke) on the germination and early seedling growth of 21 herbaceous species in Central Anatolian steppe, Turkey. We made an experiment including one smoke and five heat-shock treatments (60, 80, 100, 120 and 140 °C for 5 min) to test whether germination percentage, mean germination time, seedling growth, and seedling vigor enhance or reduce in the treatments in comparison to the controls. Seeds of all species were able to tolerate low heat shocks, but moderate and high heat shocks had a negative impact on germination and seedling growth. In Stachys byzantina , germination was stimulated by the smoke treatment. Smoke and low heat shocks positively affected the seedling vigor index of six species. The results suggest that the seeds of plant species in Central Anatolian steppes are resistant to low-intensity surface fires, but not high-intensity crown fires and that some species take advantage from surface fires. Our results contribute to understanding the role of fire in temperate grassland ecosystems. [ABSTRACT FROM AUTHOR]

Abstract: Patchy distribution of sagebrush (Artemisia tridentata), also known as ‘islands of fertility’ strongly modulates the biogeochemical dynamics of the sagebrush-steppe ecosystem. We tested the hypothesis that islands of fertility influence the spatial structure of soil respiration. We employed a spatial sampling design, which consisted of 0.5 m diameter plots placed in a repeating pattern within a grid of 12 m × 12 m. At each sample point, we measured soil respiration rates, aboveground vegetation cover, root biomass to 10 cm depth and distance and dimensions of the nearest shrub in four quadrants. Total aboveground leaf biomass was estimated from allometric relationships. We found that soil respiration was spatially autocorrelated with a range of 2.5–8.82 m in June and July in 2009. While soil temperature modulated the spatial pattern of soil respiration, the influence of islands of fertility was not as strong as expected. Spatial autocorrelation also highlights the importance of proper sampling design of point measurements of soil respiration and provides strong justification for including additional factors such as vegetation cover and aboveground leaf biomass in future mechanistic models of soil respiration. [Copyright &y& Elsevier]

Abstract: Prescribed fire is commonly applied world-wide as a tool for enhancing habitats and altering resource-selection patterns of grazing animals. A scientific basis for this practice has been established in some ecosystems but its efficacy has not been rigorously evaluated on mesic sagebrush steppe. Beginning in 2003, resource-selection patterns of beef cows were investigated using global positioning system (GPS) collars for 2 years before and for 5 years after a fall prescribed burn was applied to mesic sagebrush steppe in the Owyhee Mountains of southwestern Idaho, USA. Resource-selection functions (RSF) developed from these data indicated cattle selected for lightly to moderately burned areas for all 5 postfire years. Cattle had been neutral towards these areas prior to the fire when their distribution was primarily affected by slope, sagebrush dominance, and distance to upland water. Resource-selection responses to the fire lasted 2–3 years longer than would be expected for fire-induced, forage-quality improvement effects. Although this is a case study and caution should be taken in extrapolating these results, if applied under conditions similar to this study, livestock producers and natural resource managers can likely use fall prescribed fire in the mesic sagebrush steppe to affect cattle resource-use patterns for 5 years postfire. [Copyright &y& Elsevier]

Abstract: The population structure, educational level and the livelihoods of 82 households of pastoral nomads, the organization of livestock husbandry and its impact on the grassland and forest ecosystems of the Dayan high valley (>2000 m a.s.l.) in the Mongolian Altai, western Mongolia, were surveyed using interviews and secondary information from official sources. Changes following the transition from centrally planned (before 1990) to market economy were analyzed. Two thirds of the monthly mean income of ca. 310 USD per nomad household is cash (ca. 55 USD) or non-cash (ca. 165 USD) income from livestock husbandry. Cashmere sale accounts for 70% of the cash income from livestock husbandry, which has led to a strong increase of goat numbers after 1990. Forests are used for livestock grazing, fuel wood collection, logging, and fruit collection. Livestock breeding and the seasonal migration of the nomad households are no longer organized by the government. To avoid transportation costs, two thirds of the families have reduced their seasonal migrations. This trend was favored by rising temperatures and earlier snowmelt during the last few decades, but resulted in a shortage of fodder and intensified forest use. Therefore, the use of grasslands and forests in the Mongolian Altai is no longer considered to be sustainable. [Copyright &y& Elsevier]

Abstract: A process-based model (VIP model) was used to partition evapotranspiration (ET) into transpiration (T) and evaporation (E). Gross ecosystem productivity (GEP) and ecosystem respiration (R e) were calculated based on CO2 fluxes measured by eddy covariance in a typical steppe. The results revealed that the water and CO2 fluxes were low before the growth of vegetation in the spring. During the growth period, plant transpiration was found to account for 33–74% of the total ET. Additionally, the variations in daily net ecosystem exchange (NEE) and GEP were found to be correlated with precipitation and T, but not ET during the study periods. The peak responses of R e to rain events lagged by 1–2 days when compared to the evaporation peak. The leaf area index (LAI) primarily regulated the changes in water use efficiency (WUE). Taken together, the results of this study indicated that the development of vegetation and the pattern of precipitation worked in concert to regulate the components of water and carbon fluxes and their coupling. [Copyright &y& Elsevier]

This study presents an assessment, resulting from consultation with experts in steppe-bird conservation (scientists, officers and conservationists) using the Delphi method, of a broad range of agri-environmental measures (AEMs) which have been applied in agricultural areas in Spain, with particular reference to four threatened steppe bird species. The measures which experts have valued most highly relate to the maintenance of fallow land, the prohibition of agrochemicals and the suspension of certain agricultural practices when the species are nesting. Other AEMs which have frequently been mentioned as beneficial for steppe birds, including the maintenance of straw-mulched fallows and the abandonment of farmland, were rejected by the experts. The assessment showed a high degree of consensus between experts, although differences between the four studied species were detected. Delphi assessment indicated that different birds need different AEMs. In addition, expert evaluation showed that different AEMs can cause the same effect on the target species, which could generate an over-implementation of measures. Finally, we evaluated the financial implementation of the AEMs selected by the Delphi using a Special Protection Area for birds (SPA) in the Madrid region as a case study. All the hypothetical scenarios used yielded assumable costs, oscillating between 1 and 2 times the current AEMs expenditure. In conclusion, in extensive agrarian systems with already high conservation merits, the implementation of AEMS could be improved using species-specific assessments, thus avoiding over-implementation and improving the fit between costs and benefits for conservation. [Copyright &y& Elsevier]

Abstract: In the western United States, overgrazing, weed invasion and wildfire have resulted in the conversion of shrub-steppe to annual grasslands, with substantial effects on ecosystem function. In these landscapes, badgers disturb large areas of soil while foraging for fossorial animals. Mounds created by badgers contained the lowest concentrations of total carbon, nitrogen and sulphur, mineral nitrogen and mineralizable nitrogen, inter-mound soils had the highest concentrations, and excavation pits had intermediate levels. Soil C:N ratio and pH were greater, and electrical conductivity and soluble Ca2+, Mg2+ and K+ were lower on mound soils compared with either pit or inter-mound soils. Larger pits generally trapped more litter, and increased litter mass equated with greater concentrations of active carbon, but only at the burned sites. Older mounds supported more vascular plants and cryptogamic crusts. Our results demonstrate reduced levels of nutrients and a higher C:N ratio on the mounds compared with either the pits or inter-mounds. Alteration to the homogeneous post-fire landscape by badgers contributes to patchiness in soils and vegetation, which is critical to the functioning of arid systems. Given their effect on soil C:N ratios, mounds may be important sites for recovery of indigenous shrub-steppe plant species. [Copyright &y& Elsevier]