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Southwestern United States (southwestern + united_states)
Selected AbstractsContemporary climate change in the Sonoran Desert favors cold-adapted speciesGLOBAL CHANGE BIOLOGY, Issue 5 2010SARAH KIMBALL Abstract Impacts of long-term climate shifts on the dynamics of intact communities within species ranges are not well understood. Here, we show that warming and drying of the Southwestern United States over the last 25 years has corresponded to a shift in the species composition of Sonoran Desert winter annuals, paradoxically favoring species that germinate and grow best in cold temperatures. Winter rains have been arriving later in the season, during December rather than October, leading to the unexpected result that plants are germinating under colder temperatures, shifting community composition to favor slow growing, water-use efficient, cold-adapted species. Our results demonstrate how detailed ecophysiological knowledge of individual species, combined with long-term demographic data, can reveal complex and sometimes unexpected shifts in community composition in response to climate change. Further, these results highlight the potentially overwhelming impact of changes in phenology on the response of biota to a changing climate. [source] Flow cytometric method for quantifying viable Mycoplasma agassizii, an agent of upper respiratory tract disease in the desert tortoise (Gopherus agassizii)LETTERS IN APPLIED MICROBIOLOGY, Issue 4 2010H.A. Mohammadpour Abstract Aims:,Mycoplasma agassizii can cause upper respiratory tract disease in the threatened desert tortoise of the Southwestern United States. Two technical challenges have impeded critical microbiological studies of this microorganism: (i) its small size limits the use of light microscopy for cell counting and (ii) its extremely slow growth in broth and agar cultures impedes colony counting. Our aim was to develop a rapid and sensitive flow cytometric method using a vital fluorescent dye to enumerate viable M. agassizii cells. Methods and Results:, Here, we demonstrate that the nonfluorescent molecule 5-carboxyfluorescein (5-CF) diacetate acetoxymethyl ester penetrates M. agassizii cell membranes and it is converted in the cytoplasm to the fluorescent molecule 5-CF by the action of intracellular esterases. Labelled mycoplasma cells can be easily detected by flow cytometry, and cultures with as few as 100 viable mycoplasma cells ml,1 can be labelled and counted in less than 1 h. Experiments using temperature-induced cell death demonstrated that only viable M. agassizii cells are labelled with this procedure. Conclusions:, A rapid and sensitive flow cytometric technique has been developed for enumerating viable M. agassizii cells. Significance and Impact of the Study:, This technique should facilitate basic immunological, biochemical and pharmacological studies of this important pathogen which may lead to new diagnostic and therapeutic methods. [source] Recommendations for Integrating Restoration Ecology and Conservation Biology in Ponderosa Pine Forests of the Southwestern United StatesRESTORATION ECOLOGY, Issue 1 2006Reed F. Noss Abstract Over the past century, ponderosa pine,dominated landscapes of the southwestern United States have been altered by human activities such as grazing, timber harvest, road building, and fire exclusion. Most forested areas within these landscapes now show increased susceptibility to stand-replacing fires, insect outbreaks, and drought-related mortality. Recent large wildfires in the region have spurred public interest in large-scale fuel reduction and restoration programs, which create perceived and real conflicts with the conservation of biodiversity. Conservation concerns include the potential for larger road networks, soil and understory disturbance, exotic plant invasion, and the removal of large trees in treated areas. Pursuing prescribed burning, thinning, or other treatments on the broad scale that many scientists and managers envision requires the reconciliation of ecological restoration with biodiversity conservation. This study presents recommendations from a workshop for integrating the principles and practices of restoration ecology and conservation biology, toward the objective of restoring the composition, structure, and function of dry ponderosa pine forests. Planning on the scale of hundreds of thousands of hectares offers opportunities to achieve multiple objectives (e.g., rare species protection and restoration of ecological structures and processes) that cannot easily be addressed on a site-by-site basis. However, restoration must be coordinated with conservation planning to achieve mutual objectives and should include strict guidelines for protection of rare, declining, and sensitive habitats and species. [source] Modified passive capillary samplers for collecting samples of snowmelt infiltration for stable isotope analysis in remote, seasonally inaccessible watersheds 1: laboratory evaluationHYDROLOGICAL PROCESSES, Issue 7 2010Marty D. Frisbee Abstract Snowmelt is the most significant source of runoff generation and recharge in many of the mountainous watersheds worldwide and this is especially true in the southwestern United States. Yet, the isotopic and geochemical composition of the soil,meltwater endmember remains poorly constrained. Using the isotopic compositions of snow and snowmelt runoff samples taken from the landscape surface as proxies for soil,meltwater endmembers is problematic since they are typically not representative of the actual composition of soil meltwater. Furthermore, the applicability of current methodologies to collect the isotopic composition of meltwater is limited because of the remote and often seasonally inaccessible nature of the terrain where snowpacks develop. Therefore, a robust methodology requiring little maintenance or monitoring is desirable. A lab experiment was conducted to determine the suitability of using a modified passive capillary sampler (M-PCAPS) design to collect snowmelt infiltration for isotopic analysis. Passive capillary samplers are constructed from fiberglass wicks that can be installed in the soil to sample vadose-zone waters under a wide range of matric potentials and require little maintenance. Results from this lab experiment indicate that the wicking process associated with M-PCAPS does not fractionate water but certain precautions are necessary to prevent exchange between the wick and the atmosphere. In this experiment, M-PCAPS effectively tracked the changing isotopic composition of a soil reservoir undergoing evaporation. Therefore, M-PCAPS provide a robust methodology to sample the isotopic composition of snowmelt infiltration in remote watersheds and similar applications. Copyright © 2009 John Wiley & Sons, Ltd. [source] Shifting covariability of North American summer monsoon precipitation with antecedent winter precipitationINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 8 2006Gregory J. McCabe Abstract Previous research has suggested that a general inverse relation exists between winter precipitation in the southwestern United States (US) and summer monsoon precipitation. In addition, it has been suggested that this inverse relation between winter precipitation and the magnitude of the southwestern US monsoon breaks down under certain climatic conditions that override the regional winter/monsoon precipitation relations. Results from this new study indicate that the winter/monsoon precipitation relations do not break down, but rather shift location through time. The strength of winter/monsoon precipitation relations, as indexed by 20-year moving correlations between winter precipitation and monsoon precipitation, decreased in Arizona after about 1970, but increased in New Mexico. The changes in these correlations appear to be related to an eastward shift in the location of monsoon precipitation in the southwestern US. This eastward shift in monsoon precipitation and the changes in correlations with winter precipitation also appear to be related to an eastward shift in July/August atmospheric circulation over the southwestern US that resulted in increased monsoon precipitation in New Mexico. Results also indicate that decreases in sea-surface temperatures (SSTs) in the central North Pacific Ocean also may be associated with the changes in correlations between winter and monsoon precipitation. Copyright © 2006 Royal Meteorological Society. [source] Pilot study of latewood-width of conifers as an indicator of variability of summer rainfall in the North American monsoon regionINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 6 2001David M. Meko Abstract The variability of the North American Monsoon System (NAMS) is important to the precipitation climatology of Mexico and the southwestern United States. Tree-ring studies have been widely applied to climatic reconstruction in western North America, but as yet, have not addressed the NAMS. One reason is the need for highly resolved seasonal dendroclimatic information. Latewood-width, the portion of the annual tree ring laid down late in the growing season, can potentially yield such information. This paper describes a pilot study of the regional summer precipitation signal in latewood-width from a network of five Pseudotsuga menziesii chronologies developed in the heart of the region of NAMS influence in Arizona, USA. Exploratory data analysis reveals that the summer precipitation signal in latewood is strong, but not equally so over the full range of summer precipitation. Scatter in the relationship increases toward higher levels of precipitation. Adjustment for removal of inter-correlation with earlywood-width appears to strengthen the summer precipitation signal in latewood-width. To demonstrate a possible application to climatic reconstruction, the latewood precipitation signal is modelled using a nonlinear model,a binary recursive classification tree (CT) that attempts to classify summers as dry or not dry from threshold values of latewood-width. The model identifies narrow latewood-width as an effective predictor of a dry summer. Of 14 summers classified dry by latewood-width for the period 1868,1992, 13 are actually dry by the instrumental precipitation record. The results suggest that geographical expansion of coverage by latewood-width chronologies and further development of statistical methods may lead to successful reconstruction of variability of the NAMS on century time scales. Copyright © 2001 Royal Meteorological Society [source] Intraspecific genetic analysis of the summer tanager Piranga rubra: implications for species limits and conservationJOURNAL OF AVIAN BIOLOGY, Issue 1 2007Tiffany M. Shepherd The summer tanager Piranga rubra is a Neotropical migrant that has experienced noted declines in the southwestern United States caused by extensive habitat loss of native riparian woodlands. This species is composed of two morphologically and behaviorally distinct taxa that traditionally have been recognized as subspecies, each occupying unique habitats in the southern part of North America. Genetic analyses of intraspecific variation are important in studies of threatened or endangered species because they can indicate whether smaller management units exist below the species level and they also provide estimates of within population variability. Using a mitochondrial DNA marker, the intraspecific genetic variation of this species is explored to determine whether the morphologically and behaviorally distinct subspecies are also genetically unique. By using traditional phylogenetic methods and building haplotype networks, results from this study indicate that the subspecies represent two phylogenetic species and should be managed as separate units. In addition, the level of gene flow among geographically isolated populations of the western subspecies is explored using Nested Clade Phylogeographic Analysis and population genetic tests. These analyses show that populations are genetically diverse and that haplotypes are shared across populations. Newly colonized populations are as diverse as older populations. This suggests that as habitat degrades in traditional breeding areas of the summer tanager, if suitable habitat elsewhere becomes available for new populations, these new colonies should be genetically diverse. [source] Nest-site selection by Common Black-Hawks in southwestern New MexicoJOURNAL OF FIELD ORNITHOLOGY, Issue 1 2008Giancarlo Sadoti ABSTRACT Despite the interest of resource managers and conservationists in the status of Common Black-Hawk (Buteogallus anthracinus) populations in the southwestern United States, little is known about their nesting success and habitat requirements. Because such information is essential for effective population and habitat management, I examined the nesting success and nest-site selection of Common Black-Hawks in southwestern New Mexico during 2000 and 2001. Of the 37 nesting attempts in 21 territories, ,1 young fledged from 25 nests (68%). Comparison of nest-sites and nonused sites suggested that breeding Common Black-Hawks selected nest-sites in areas with a sparser and shorter subcanopy tree layer and in trees with a smaller trunk diameter and a greater minimum crown diameter. These differences appear to be related to variation in forest ages within territories, with nonused sites having fewer, but older, canopy trees than nest-sites. Sites with younger, smaller subcanopy trees may provide forest structure for more effective foraging, whereas the characteristics of younger nest tree canopies may reduce the risk of nest predation or offer more protection from inclement weather. Due to the limited range of this species in the southwestern United States, efforts to encourage the establishment and maturation of riparian forests in Common Black-Hawk breeding areas could be important in sustaining available nesting habitat and, in turn, maintaining or expanding current population levels. SINOPSIS Aunque existe interés de parte de profesionales en manejo de recursos y conservacionistas en el estatus de las poblaciones de Buteogallus anthracinus en el sudoeste de los Estados Unidos, poco se conoce sobre su éxito de anidamiento y requerimientos de hábitat. Por la razón que esta información es esencial para el éxito del manejo poblacional y del hábitat para esta especie, examiné el éxito de anidamiento y la selección del lugar de anidamiento de Buteogallus anthracinus en el sudeste del estado de Nueva México durante el 2000 y el 2001. De los 37 intentos de anidamiento en 21 territorios, ,1 de los polluelos volaron de 25 nidos (68%). Una comparación entre lugares donde se ubicaban los nidos y sitios no utilizados para anidar indica que individuos seleccionaron lugares para anidar en áreas con una menor cobertura y una menor altura del sub-dosel. Adicionalmente, los nidos fueron ubicados en árboles con un menor diámetro del tronco y con un mayor diámetro mínimo de la corona. Estas diferencias parecen ser relacionadas a la variación en la edad del bosque dentro de los territorios, con sitios no utilizados caracterizados por un número menor de árboles del dosel pero las cuales tienen una edad mayor que los árboles del dosel en los sitios donde se ubicaron los nidos. Sitios con árboles en el sub-dosel de menor edad y de menor tamaño podrían proveer la estructura del bosque necesaria para un forrajeo mas efectivo, mientras que las características de las coronas de los árboles de menor edad en la cual se encuentra el nido podrían reducir el riesgo de la depredación del nido o proveer mas protección de mal tiempo. Dado el rango limitado de esta especie en el sudeste de los Estados Unidos, los esfuerzos para animar el establecimiento y la maduración de los bosques riparios en las áreas de anidamiento de esta especie podrían ser importantes para mantener el hábitat disponible para anidar y a la vez mantener o expandir los tamaños actuales de las poblaciones. [source] PRECIPITATION CHANGES FROM 1956 TO 1996 ON THE WALNUT GULCH EXPERIMENTAL WATERSHED,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 1 2002Mary H. Nichols ABSTRACT: The climate of Southern Arizona is dominated by summer precipitation, which accounts for over 60 percent of the annual total. Summer and non-summer precipitation data from the USDA-ARS Walnut Gulch Experimental Watershed are analyzed to identify trends in precipitation characteristics from 1956 to 1996. During this period, annual precipitation increased. The annual precipitation increase can be attributed to an increase in precipitation during non-summer months, and is paralleled by an increase in the proportion of annual precipitation contributed during non-summer months. This finding is consistent with previously reported increases in non-summer precipitation in the southwestern United States. Detailed event data were analyzed to provide insight into the characteristics of precipitation events during this time period. Precipitation event data were characterized based on the number of events, event precipitation amount, 30-minute event intensity, and event duration. The trend in non-summer precipitation appears to be a result of increased event frequency since the number of events increased during nonsummer months, although the average amount per event, average event intensity, and average event duration did not. During the summer "monsoon" season, the frequency of recorded precipitation events increased but the average precipitation amount per event decreased. Knowledge of precipitation trends and the characteristics of events that make up a precipitation time series is a critical first step in understanding and managing water resources in semiarid ecosystems. [source] Coccidioidomycosis in liver transplantationLIVER TRANSPLANTATION, Issue 1 2006Janis E. Blair Coccidioidomycosis is an endemic fungal infection in the southwestern United States. It causes morbidity and mortality among solid organ transplant recipients who reside in or visit the endemic area or who receive organs from donors infected with the fungus. This paper reviews current literature addressing these infections in liver transplantation programs, including risk factors, clinical manifestations in persons with cirrhosis or who have had a liver transplantation, prophylaxis, treatment, and outcomes. Liver Transpl 12:31,39, 2006. © 2005 AASLD. [source] Characterization of microsatellite loci in Kearney's bluestar (Amsonia kearneyana) and cross-amplification in other Amsonia speciesMOLECULAR ECOLOGY RESOURCES, Issue 4 2004J. RICK TOPINKA Abstract Kearney's bluestar (Amsonia kearneyana) is a highly endangered herbaceous perennial in the family Apocynaceae. The species is found only in the Baboquivari Mountains of southern Arizona. We report the isolation and development of 12 microsatellite loci for Kearney's bluestar. Numbers of alleles ranged from two to four and observed heterozygosities ranged from 0.20 to 0.80 in the nine loci found to be polymorphic in the test population. All loci were also tested for cross-amplification in five other Amsonia species representing two subgenera from the southwestern United States. Some loci that were not polymorphic in the Kearney's bluestar were polymorphic in other species. [source] Market Perceptions and Opportunities for Native Plant Production on the Southern Colorado PlateauRESTORATION ECOLOGY, Issue 2010Donna L. Peppin Increases in revegetation activities have created a large demand for locally adapted native plant materials (NPM) in the southwestern United States. Currently, there is a minimal supply of local genotypes to meet this demand. We investigated the potential for the initiation of a native plant market in the southern Colorado Plateau. Through a literature search, interviews, and site visits, we identified existing native plant markets outside of the region as useful models to help initiate a regional market. We used web-based surveys to identify and analyze current and future NPM needs and concerns. Survey results indicate that management policy strongly drives decisions regarding the use and purchase of NPM. From a demand perspective , lack of availability and cost of NPM has kept purchasing minimal, despite policy changes favoring the use of natives. For suppliers, further development of NPM is limited by inconsistent and unreliable demand and lack of production knowledge. The knowledge and tools necessary to initiate an NPM market are available, but inadequate funding sources and insufficient information sharing hinder its development. Communication among producers, land managers, buyers, and researchers, as well as partnerships with local growers, appear to be vital to initiating a functional market. [source] Recommendations for Integrating Restoration Ecology and Conservation Biology in Ponderosa Pine Forests of the Southwestern United StatesRESTORATION ECOLOGY, Issue 1 2006Reed F. Noss Abstract Over the past century, ponderosa pine,dominated landscapes of the southwestern United States have been altered by human activities such as grazing, timber harvest, road building, and fire exclusion. Most forested areas within these landscapes now show increased susceptibility to stand-replacing fires, insect outbreaks, and drought-related mortality. Recent large wildfires in the region have spurred public interest in large-scale fuel reduction and restoration programs, which create perceived and real conflicts with the conservation of biodiversity. Conservation concerns include the potential for larger road networks, soil and understory disturbance, exotic plant invasion, and the removal of large trees in treated areas. Pursuing prescribed burning, thinning, or other treatments on the broad scale that many scientists and managers envision requires the reconciliation of ecological restoration with biodiversity conservation. This study presents recommendations from a workshop for integrating the principles and practices of restoration ecology and conservation biology, toward the objective of restoring the composition, structure, and function of dry ponderosa pine forests. Planning on the scale of hundreds of thousands of hectares offers opportunities to achieve multiple objectives (e.g., rare species protection and restoration of ecological structures and processes) that cannot easily be addressed on a site-by-site basis. However, restoration must be coordinated with conservation planning to achieve mutual objectives and should include strict guidelines for protection of rare, declining, and sensitive habitats and species. [source] | |||||||||||||