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Great Basin (great + basin)
Selected AbstractsModeled Effects of Sagebrush-Steppe Restoration on Greater Sage-Grouse in the Interior Columbia Basin, U.S.A.CONSERVATION BIOLOGY, Issue 5 2002Michael J. Wisdom Consequently, managers of FS,BLM lands need effective strategies to recover sagebrush (Artemisia spp.) habitats on which this species depends. In response to this need, we evaluated the potential benefits of two restoration scenarios on Greater Sage-Grouse in the interior Columbia Basin and adjacent portions of the Great Basin of the western United States. Scenario 1 assumed a 50% reduction in detrimental grazing effects (through changes in stocking rates and grazing systems) and a six-fold increase in areas treated with active restoration (e.g., prescribed burning, native seedings, wildfire suppression) compared with future management proposed by the FS,BLM. Scenario 2 assumed a 100% reduction in detrimental grazing effects and the same increase in active restoration as scenario 1. To evaluate benefits, we estimated the risk of population extirpation for sage grouse 100 years in the future under the two scenarios and compared this risk with that estimated for proposed (100-year) FS,BLM management. We used estimates of extirpation risk for historical (circa 1850,1890) and current time periods as a context for our comparison. Under historical conditions, risk of extirpation was very low on FS,BLM lands, but increased to a moderate probability under current conditions. Under proposed FS,BLM management, risk of extirpation on FS,BLM lands increased to a high probability 100 years in the future. Benefits of the two restoration scenarios, however, constrained the future risk of extirpation to a moderate probability. Our results suggest that expansive and sustained habitat restoration can maintain desired conditions and reduce future extirpation risk for sage grouse on FS,BLM lands in western North America. The continued spread of exotic plants, however, presents a formidable challenge to successful restoration and warrants substantial research and management attention. Resumen: Los hábitats del urogallo (Centrocercus urophasianus) han disminuido a lo largo de la región occidental de Norteamérica, y la mayoría de los hábitats restantes ocurren en terrenos administrados por el Servicio Forestal de E.U.A. (SF) y el Buró de Administración de Tierras ( BAT ). Por lo tanto, los encargados de las tierras SF,BAT necesitan estrategias eficaces para recuperar los hábitats de artemisa (Artemisia spp.) de los cuales depende esta especie. En respuesta a esta necesidad, evaluamos los beneficios potenciales de dos escenarios de restauración sobre el urogallo en el interior de la Cuenca del Columbia y porciones adyacentes de la Gran Cuenca del occidente de los Estados Unidos. El escenario 1 supone una reducción del 50% en los efectos perjudiciales del pastoreo ( por medio de cambios en las tasas de aprovisionamiento y en los sistemas de pastoreo) y un incremento de seis veces en la superficie de las áreas tratadas con restauración activa ( por ejemplo, quemas prescritas, plántulas nativas, supresión de fuego no controlado) comparada con la administración futura propuesta por el SF,BAT. El escenario 2 supone una reducción del 100% en los efectos de pastoreo perjudiciales y el mismo aumento en la restauración activa que en el escenario 1. Para evaluar los beneficios, estimamos el riesgo de extirpación de la población de urogallos en 100 años bajo los dos escenarios y comparamos este riesgo con el riesgo estimado por la propuesta de manejo de SF,BAT (100-años). Utilizamos estimaciones del riesgo de extirpación en períodos históricos (entre 1850 y 1890) y actuales como contexto para nuestra comparación. Bajo condiciones históricas, el riesgo de extirpación fue muy bajo en los terrenos SF,BAT pero aumentó a una probabilidad moderada bajo condiciones actuales. Bajo la administración propuesta por SF,BAT, el riesgo de extirpación en los terrenos SF,BAT aumentó a una alta probabilidad 100 años en el futuro. Sin embargo, los beneficios de los dos escenarios de restauración constriñen el riesgo de extirpación a una probabilidad moderada. Nuestros resultados sugieren que la restauración expansiva y sostenida del hábitat puede mantener condiciones deseadas y reduce el riesgo de extirpación de urogallos en terrenos SF,BAT en la región occidental de Norteamérica. Sin embargo, la continua extensión de plantas exóticas representa un reto formidable para la restauración exitosa y justifica considerable investigación y atención de manejo. [source] Performance of Greater Sage-Grouse Models for Conservation Assessment in the Interior Columbia Basin, U.S.A.CONSERVATION BIOLOGY, Issue 5 2002Michael J. Wisdom Consequently, we evaluated the performance of two models designed to assess landscape conditions for Greater Sage-Grouse across 13.6 million ha of sagebrush steppe in the interior Columbia Basin and adjacent portions of the Great Basin of the western United States (referred to as the basin). The first model, the environmental index model, predicted conditions at the scale of the subwatershed (mean size of approximately 7800 ha) based on inputs of habitat density, habitat quality, and effects of human disturbance. Predictions ranged on a continuous scale from 0 for lowest environmental index to 2 for optimal environmental index. The second model, the population outcome model, predicted the composite, range-wide conditions for sage grouse based on the contribution of environmental index values from all subwatersheds and measures of range extent and connectivity. Population outcomes were expressed as five classes (A through E) that represented a gradient from continuous, well-distributed populations (outcome A) to sparse, highly isolated populations with a high likelihood of extirpation (outcome E). To evaluate performance, we predicted environmental index values and population outcome classes in areas currently occupied by sage grouse versus areas where extirpation has occurred. Our a priori expectations were that models should predict substantially worse environmental conditions ( lower environmental index) and a substantially higher probability of extirpation ( lower population outcome class) in extirpated areas. Results for both models met these expectations. For example, a population outcome of class E was predicted for extirpated areas, as opposed to class C for occupied areas. These results suggest that our models provided reliable landscape predictions for the conditions tested. This finding is important for conservation planning in the basin, where the models were used to evaluate management of federal lands for sage grouse. Resumen: Modelos válidos de hábitat y de poblaciones del urogallo (Centrocercus urophasianus) son una necesidad crítica para su manejo debido a la creciente preocupación por la viabilidad de la población. Por lo tanto, evaluamos el funcionamiento de dos modelos diseñados para evaluar las condiciones del paisaje para el urogallo en 13.6 millones de ha de la estepa de artemisa en la Cuenca Columbia Interior y las porciones adyacentes de la Gran Cuenca de los Estados Unidos occidentales (referidos como cuenca). El primer modelo (modelo de índice ambiental) predijo condiciones a escala de la subcuenca (tamaño promedio , 7800 ha) basado en información de la densidad del hábitat, calidad del hábitat y efectos de la perturbación humana. Las predicciones variaron en una escala continua a partir de 0 (el índice ambiental más bajo) a 2 (índice ambiental óptimo). El segundo modelo (modelo del resultado de la población) predijo las condiciones compuestas, de amplio rango, para el urogallo con base en la contribución de los valores de índice ambiental de todas las subcuencas y las medidas de extensión y de conectividad de la pradera. Los resultados de la población fueron expresados en cinco clases (A - E) que representan un gradiente de poblaciones continuas, bien-distribuidas (resultado A) a poblaciones escasas, altamente aisladas con una alta probabilidad de extirpación (resultado E). Para evaluar el funcionamiento, predijimos valores de índice ambiental y resultados de la población en las áreas actualmente ocupadas por urogallos versus áreas donde ha ocurrido la extirpación. Nuestras expectativas a priori eran que los modelos deben predecir condiciones ambientales substancialmente peores (índice ambiental más bajo) y una probabilidad de extirpación sustancialmente mayor (menor resultado de la población) en áreas extirpadas. Los resultados para ambos modelos cumplieron estas expectativas. Por ejemplo, se predijo un resultado de la población de la clase E para áreas extirpadas, en comparación con la clase C para áreas ocupadas. Estos resultados sugieren que nuestros modelos proporcionaron predicciones de paisaje confiables para las condiciones probadas. Este hallazgo es importante para planeación de la conservación de la cuenca, donde los modelos fueron utilizados para evaluar el manejo de terrenos federales para urogallos. [source] Conversion of sagebrush shrublands to exotic annual grasslands negatively impacts small mammal communitiesDIVERSITY AND DISTRIBUTIONS, Issue 5 2009Steven M. Ostoja Abstract Aim, The exotic annual cheatgrass (Bromus tectorum) is fast replacing sagebrush (Artemisia tridentata) communities throughout the Great Basin Desert and nearby regions in the Western United States, impacting native plant communities and altering fire regimes, which contributes to the long-term persistence of this weedy species. The effect of this conversion on native faunal communities remains largely unexamined. We assess the impact of conversion from native perennial to exotic annual plant communities on desert rodent communities. Location, Wyoming big sagebrush shrublands and nearby sites previously converted to cheatgrass-dominated annual grasslands in the Great Basin Desert, Utah, USA. Methods, At two sites in Tooele County, Utah, USA, we investigated with Sherman live trapping whether intact sagebrush vegetation and nearby converted Bromus tectorum -dominated vegetation differed in rodent abundance, diversity and community composition. Results, Rodent abundance and species richness were considerably greater in sagebrush plots than in cheatgrass-dominated plots. Nine species were captured in sagebrush plots; five of these were also trapped in cheatgrass plots, all at lower abundances than in the sagebrush. In contrast, cheatgrass-dominated plots had no species that were not found in sagebrush. In addition, the site that had been converted to cheatgrass longer had lower abundances of rodents than the site more recently converted to cheatgrass-dominated plots. Despite large differences in abundances and species richness, Simpson's D diversity and Shannon-Wiener diversity and Brillouin evenness indices did not differ between sagebrush and cheatgrass-dominated plots. Main conclusions, This survey of rodent communities in native sagebrush and in converted cheatgrass-dominated vegetation suggests that the abundances and community composition of rodents may be shifting, potentially at the larger spatial scale of the entire Great Basin, where cheatgrass continues to invade and dominate more landscape at a rapid rate. [source] Patterns of spatial autocorrelation of assemblages of birds, floristics, physiognomy, and primary productivity in the central Great Basin, USADIVERSITY AND DISTRIBUTIONS, Issue 3 2006Erica Fleishman ABSTRACT We fitted spatial autocorrelation functions to distance-based data for assemblages of birds and for three attributes of birds' habitats at 140 locations, separated by up to 65 km, in the Great Basin (Nevada, USA). The three habitat characteristics were taxonomic composition of the vegetation, physical structure of the vegetation, and a measure of primary productivity, the normalized difference vegetation index, estimated from satellite imagery. We found that a spherical model was the best fit to data for avifaunal composition, vegetation composition, and primary productivity, but the distance at which spatial correlation effectively was zero differed substantially among data sets (c. 30 km for birds, 20 km for vegetation composition, and 60 km for primary productivity). A power-law function was the best fit to data for vegetation structure, indicating that the structure of vegetation differed by similar amounts irrespective of distance between locations (up to the maximum distance measured). Our results suggested that the spatial structure of bird assemblages is more similar to vegetation composition than to either vegetation structure or primary productivity, but is autocorrelated over larger distances. We believe that the greater mobility of birds compared with plants may be responsible for this difference. [source] Microbiology and geochemistry of Little Hot Creek, a hot spring environment in the Long Valley CalderaGEOBIOLOGY, Issue 2 2010T. J. VICK A culture-independent community census was combined with chemical and thermodynamic analyses of three springs located within the Long Valley Caldera, Little Hot Creek (LHC) 1, 3, and 4. All three springs were approximately 80 °C, circumneutral, apparently anaerobic and had similar water chemistries. 16S rRNA gene libraries constructed from DNA isolated from spring sediment revealed moderately diverse but highly novel microbial communities. Over half of the phylotypes could not be grouped into known taxonomic classes. Bacterial libraries from LHC1 and LHC3 were predominantly species within the phyla Aquificae and Thermodesulfobacteria, while those from LHC4 were dominated by candidate phyla, including OP1 and OP9. Archaeal libraries from LHC3 contained large numbers of Archaeoglobales and Desulfurococcales, while LHC1 and LHC4 were dominated by Crenarchaeota unaffiliated with known orders. The heterogeneity in microbial populations could not easily be attributed to measurable differences in water chemistry, but may be determined by availability of trace amounts of oxygen to the spring sediments. Thermodynamic modeling predicted the most favorable reactions to be sulfur and nitrate respirations, yielding 40,70 kJ mol,1 e, transferred; however, levels of oxygen at or below our detection limit could result in aerobic respirations yielding up to 100 kJ mol,1 e, transferred. Important electron donors are predicted to be H2, H2S, S0, Fe2+ and CH4, all of which yield similar energies when coupled to a given electron acceptor. The results indicate that springs associated with the Long Valley Caldera contain microbial populations that show some similarities both to springs in Yellowstone and springs in the Great Basin. [source] GREAT BASIN IMAGERY IN NEWSPAPER COVERAGE OF YUCCA MOUNTAIN§GEOGRAPHICAL REVIEW, Issue 4 2005SOREN C. LARSEN ABSTRACT. Place imagery in printed news is a vital but overlooked feature of the public debate regarding the disposal of the nation's nuclear waste in the proposed Yucca Mountain repository northwest of Las Vegas, Nevada. A content analysis of newspaper coverage reveals that participants use Great Basin imagery in the rhetorical strategies involved in making arguments for and against the site. This article identifies specific elements in the news-production process that privilege certain conceptualizations of the Great Basin over others, and it highlights alternative visions that have appeared in editorials, travel pieces, and commentaries. Taken together, the data and analysis suggest that journalistic sensitivity to value-laden imagery can result in more balanced and critical news accounts of public debate. [source] Comparison of phenology trends by land cover class: a case study in the Great Basin, USAGLOBAL CHANGE BIOLOGY, Issue 2 2008BETHANY A. BRADLEY Abstract Direct impacts of human land use and indirect impacts of anthropogenic climate change may alter land cover and associated ecosystem function, affecting ecological goods and services. Considerable work has been done to identify long-term global trends in vegetation greenness, which is associated with primary productivity, using remote sensing. Trend analysis of satellite observations is subject to error, and ecosystem change can be confused with interannual variability. However, the relative trends of land cover classes may hold clues about differential ecosystem response to environmental forcing. Our aim was to identify phenological variability and 10-year trends for the major land cover classes in the Great Basin. This case study involved two steps: a regional, phenology-based land cover classification and an identification of phenological variability and 10-year trends stratified by land cover class. The analysis used a 10-year time series of Advanced Very High Resolution Radiometer satellite data to assess regional scale land cover variability and identify change. The phenology-based regional classification was more detailed and accurate than national or global products. Phenological variability over the 10-year period was high, with substantial shifts in timing of start of season of up to 9 weeks. The mean long-term trends of montane land cover classes were significantly different from valley land cover classes due to a poor response of montane shrubland and pinyon-juniper woodland to the early 1990s drought. The differential response during the 1990s suggests that valley ecosystems may be more resilient and montane ecosystems more susceptible to prolonged drought. This type of regional-scale land cover analysis is necessary to characterize current patterns of land cover phenology, distinguish between anthropogenically driven land cover change and interannual variability, and identify ecosystems potentially susceptible to regional and global change. [source] North American weather-type frequency and teleconnection indicesINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 1 2003Scott C. Sheridan Abstract The impact of teleconnections upon the surface climate has largely been examined via a response in monthly mean temperature or total precipitation. In this paper, a different approach is undertaken, by examining the response of synoptic weather-type frequencies to different teleconnection phases. For over 330 stations in the USA and Canada, the Spatial Synoptic Classification scheme has classified each day in each station's period of record into one of seven weather-type categories, based on thermal, moisture, and other characteristics. The differences in how frequently these different weather types occur in different phases of the North Atlantic Oscillation (NAO) and Pacific,North American (PNA) teleconnection patterns is assessed, for Canadian stations from 1953 to 1993, and for US stations from 1950 to 1999. For PNA, a significant shift in the transitional frequency is observed, suggesting changes in storm track. Concomitantly, a large shift in Dry Polar and Moist Tropical frequencies is observed across the continent. Across the West, in +PNA wintertime months far fewer Dry Polar days are observed. Across the eastern USA, these polar intrusions are more common, and Moist Tropical is diminished significantly. The frequency of the transitional situation is also correlated with NAO phase, with differences as large as a factor of two across much of Canada and the northern USA. In northeastern Canada, there is a large replacement of Moist Polar conditions with Dry Polar conditions during +NAO. Farther south, however, across the eastern USA, both polar weather types occur much less often with +NAO. Although previous research has discovered eastern North American connections to the NAO, this research has shown that the connections often extend into the interior West during much of the year. Particularly strong in the spring, Dry Tropical conditions are much more common with +NAO throughout much of the continent, as far west as the Great Basin. Copyright © 2003 Royal Meteorological Society. [source] Relationships between expanding pinyon,juniper cover and topography in the central Great Basin, NevadaJOURNAL OF BIOGEOGRAPHY, Issue 5 2008Bethany A. Bradley Abstract Aim, Increasing geographical range and density of conifers is a major form of land-cover change in the western United States, affecting fire frequency, biogeochemistry and possibly biodiversity. However, the extent and magnitude of the change are uncertain. This study aimed to quantify the relationship between changing conifer cover and topography. Location, The central Great Basin in the state of Nevada, USA. Methods, We used a series of Landsat Thematic Mapper satellite images from 1986, 1995 and 2005 to map change in pinyon,juniper woodlands (Pinus monophylla, Juniperus spp.) in the montane central Great Basin of Nevada. We derived fractional greenness for each year using spectral mixture analysis and identified all areas with an above average increase in greenness from 1986 to 1995 and 1995 to 2005. Results, Areas with high fractional greenness in 2005 were most likely to occur at elevations between 2200 and 2600 m a.s.l. Increases in fractional greenness between 1986 and 2005 were most likely to occur at elevations below 2000 m a.s.l. and on south-facing slopes. However, relationships between elevation and increasing greenness for individual mountain ranges varied considerably from the average trend. Fractional greenness values measured by Landsat suggest that the majority of pinyon,juniper woodlands have not reached their maximum potential tree cover. Main conclusions, Expansion of pinyon,juniper at low elevations and on south-facing slopes probably reflects increasing precipitation in the 20th century, higher water use efficiency caused by increasing atmospheric CO2 in the late 20th century and livestock grazing at the interface between shrubland and woodland. Identification of the spatial relationships between changing fractional greenness of pinyon,juniper woodland and topography can inform regional land management and improve projections of long-term ecosystem change. [source] The paternal-sex-ratio (PSR) chromosome in natural populations of Nasonia (Hymenoptera: Chalcidoidea)JOURNAL OF EVOLUTIONARY BIOLOGY, Issue 6 2000L. W. Beukeboom Selfish genetic elements may be important in promoting evolutionary change. Paternal sex ratio (PSR) is a selfish B chromosome that causes all-male families in the haplodiploid parasitic wasp Nasonia vitripennis, by inducing paternal genome loss in fertilized eggs. The natural distribution and frequency of this chromosome in North American populations of N. vitripennis was investigated using a combination of phenotypic and molecular assays. Sampling throughout North America failed to recover PSR except from populations in the Great Basin area of western North America. Extensive sampling of Great Basin populations revealed PSR in frequencies ranging from 0 to 6% at different collection sites, and extended its distribution to Idaho and Wyoming. Intensive sampling in upstate New York did not detect the chromosome. Frequencies of the maternal-sex ratio distorter (MSR), son killer (SK) and virgin females ranged from 0 to 12%. Paternal sex ratio may be restricted to the Great Basin because its spread is hampered by geographical barriers, or because populations in other areas are not conducive to PSR maintenance. However, it cannot be ruled out that PSR occurs in other regions at very low frequencies. The apparent limited distribution and low frequency of PSR suggest that it will have relatively little impact on genome evolution in Nasonia. [source] POTENTIAL ECONOMIC IMPACTS OF CHANGES IN WATER AVAILABILITY ON AGRICULTURE IN THE TRUCKEE AND CARSON RIVER BASINS, NEVADA, USA,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 4 2006Levan Elbakidze ABSTRACT: Effects of climate change are likely to be detected in nearly all sectors and regions of the economy, with both winners and losers. One of the consequences of climatic changes could be altered regional water supplies. This paper presents an investigation of regional agricultural implications of changes in water availability. Specifically, using a profit maximization approach, the economic consequences of altered water availability in the Great Basin of Nevada are analyzed in terms of the effects on net returns of agricultural producers. Under the scenarios analyzed in this paper, it is found that with adequate water systems, increase in streamflow and consequent increase in water availability could significantly benefit agricultural producers of this region. Net returns to irrigators could increase by 8 to 13 percent, not taking into account the possibility of changes in crop yields and prices. It is also shown that the benefits from increased water availability are sensitive to likely crop yield and price changes. The potential for adverse effects of climatic changes on water supply is also considered by analyzing the effects of decreased water availability. Under decreased water availability scenarios, farmer net returns decrease substantially. [source] Phylogeography of the mountain chickadee (Poecile gambeli): diversification, introgression, and expansion in response to Quaternary climate changeMOLECULAR ECOLOGY, Issue 5 2007GARTH M. SPELLMAN Abstract Since the late 1990s, molecular techniques have fuelled debate about the role of Pleistocene glacial cycles in structuring contemporary avian diversity in North America. The debate is still heated; however, there is widespread agreement that the Pleistocene glacial cycles forced the repeated contraction, fragmentation, and expansion of the North American biota. These demographic processes should leave genetic ,footprints' in modern descendants, suggesting that detailed population genetic studies of contemporary species provide the key to elucidating the impact of the late Quaternary (late Pleistocene,Holocene). We present an analysis of mitochondrial DNA (mtDNA) variation in the mountain chickadee (Poecile gambeli) in an attempt to examine the genetic evidence of the impact of the late Quaternary glacial cycles. Phylogenetic analyses reveal two strongly supported clades of P. gambeli: an Eastern Clade (Rocky Mountains and Great Basin) and a Western Clade (Sierra Nevada and Cascades). Post-glacial introgression is apparent between these two clades in the Mono Lake region of Central California. Within the Eastern Clade there is evidence of isolation-by-distance in the Rocky Mountain populations, and of limited gene flow into and around the Great Basin. Coalescent analysis of genetic variation in the Western Clade indicates that northern (Sierra Nevada/Cascades) and southern (Transverse/Peninsular Ranges) populations have been isolated and evolving independently for nearly 60 000 years. [source] Geological barriers and restricted gene flow in the holarctic skipper Hesperia comma (Hesperiidae)MOLECULAR ECOLOGY, Issue 11 2004M. L. FORISTER Abstract Patterns of genetic variation within a species may be a consequence of historical factors, such as past fragmentation, as well as current barriers to gene flow. Using sequence data from the mitochondrial cytochrome oxidase subunit II region (COII) and the nuclear gene wingless, we conducted a phylogeographical study of the holarctic skipper Hesperia comma to elucidate patterns of genetic diversity and to infer historical and contemporary processes maintaining genetic variation. One hundred and fifty-one individuals were sampled from throughout North America and Eurasia, focusing on California and adjacent regions in the western United States where morphological diversity is highest compared to the rest of the range. Analyses of sequence data obtained from both genes revealed a well-supported division between the Old and New World. Within western North America, wingless shows little geographical structure, while a hierarchical analysis of genetic diversity of COII sequences indicates three major clades: a western clade in Oregon and Northern California, an eastern clade including the Great Basin, Rocky Mountains and British Columbia, and a third clade in southern California. The Sierra Nevada and the Transverse Ranges appear to be the major barriers to gene flow for H. comma in the western United States. Relatively reduced haplotype diversity in Eurasia compared to North America suggests that populations on the two continents have been affected by different historical processes. [source] A Landscape Approach for Ecologically Based Management of Great Basin ShrublandsRESTORATION ECOLOGY, Issue 5 2009Michael J. Wisdom Abstract Native shrublands dominate the Great Basin of western of North America, and most of these communities are at moderate or high risk of loss from non-native grass invasion and woodland expansion. Landscape-scale management based on differences in ecological resistance and resilience of shrublands can reduce these risks. We demonstrate this approach with an example that focuses on maintenance of sagebrush (Artemisia spp.) habitats for Greater Sage-grouse (Centrocercus urophasianus), a bird species threatened by habitat loss. The approach involves five steps: (1) identify the undesired disturbance processes affecting each shrubland community type; (2) characterize the resistance and resilience of each shrubland type in relation to the undesired processes; (3) assess potential losses of shrublands based on their resistance, resilience, and associated risk; (4) use knowledge from these steps to design a landscape strategy to mitigate the risk of shrubland loss; and (5) implement the strategy with a comprehensive set of active and passive management prescriptions. Results indicate that large areas of the Great Basin currently provide Sage-grouse habitats, but many areas of sagebrush with low resistance and resilience may be lost to continued woodland expansion or invasion by non-native annual grasses. Preventing these losses will require landscape strategies that prioritize management areas based on efficient use of limited resources to maintain the largest shrubland areas over time. Landscape-scale approaches, based on concepts of resistance and resilience, provide an essential framework for successful management of arid and semiarid shrublands and their native species. [source] | ||||||||||||||||||||||||||||