Desert salt flats as oases for the spider Saltonia incerta Banks (Araneae: Dictynidae).

PubMed

Crews, Sarah C; Gillespie, Rosemary G

2014-10-01

The deserts of southwestern North America have undergone dramatic changes over their recent geological history including large changes in size and connectivity during the Pleistocene glaciopluvial cycles. This study examines the population history of the rare spider Saltonia incerta, once thought to be extinct, to determine the role of past climatological events in shaping the structure of the species. This species is restricted to salt crusts of intermittent or dry lakes, streams or rivers in the desert southwest, a region that was much wetter during glacial periods. We examine the distribution and genetic variability of populations to test whether there is recent dispersal throughout the range of the species. Analyses of mitochondrial and nuclear DNA indicate significant population structure, with one major clade comprising New Mexico localities and one comprising California-northern Baja California localities. Finer-scale structure is evident within the California clade, although not all of the subclades are reciprocally monophyletic. However, isolation with migration analysis suggests that migration is very low to non-existent. These results extend the known distribution of Saltonia, provide genetic evidence of strong isolation among localities within drainage basins and between drainage basins and provide a mechanistic understanding of population connectivity after the aridification of the American southwest. The implication is that although the species' distribution has been fragmented, populations have persisted throughout this area, suggesting that desert salt flats may have served as refugia for at least some terrestrial species.

Desert salt flats as oases for the spider Saltonia incerta Banks (Araneae: Dictynidae)

PubMed Central

Crews, Sarah C; Gillespie, Rosemary G

2014-01-01

The deserts of southwestern North America have undergone dramatic changes over their recent geological history including large changes in size and connectivity during the Pleistocene glaciopluvial cycles. This study examines the population history of the rare spider Saltonia incerta, once thought to be extinct, to determine the role of past climatological events in shaping the structure of the species. This species is restricted to salt crusts of intermittent or dry lakes, streams or rivers in the desert southwest, a region that was much wetter during glacial periods. We examine the distribution and genetic variability of populations to test whether there is recent dispersal throughout the range of the species. Analyses of mitochondrial and nuclear DNA indicate significant population structure, with one major clade comprising New Mexico localities and one comprising California-northern Baja California localities. Finer-scale structure is evident within the California clade, although not all of the subclades are reciprocally monophyletic. However, isolation with migration analysis suggests that migration is very low to non-existent. These results extend the known distribution of Saltonia, provide genetic evidence of strong isolation among localities within drainage basins and between drainage basins and provide a mechanistic understanding of population connectivity after the aridification of the American southwest. The implication is that although the species' distribution has been fragmented, populations have persisted throughout this area, suggesting that desert salt flats may have served as refugia for at least some terrestrial species. PMID:25614800

De-icing salt contamination reduces urban tree performance in structural soil cells.

PubMed

Ordóñez-Barona, Camilo; Sabetski, Vadim; Millward, Andrew A; Steenberg, James

2018-03-01

Salts used for de-icing roads and sidewalks in northern climates can have a significant impact on water quality and vegetation. Sub-surface engineering systems, such as structural soil cells, can regulate water runoff and pollutants, and provide the necessary soil volume and irrigation to grow trees. However, the ability of such systems to manage de-icing salt contamination, and the impact of this contamination on the trees growing in them, have not been evaluated. We report on an field investigation of de-icing salt contamination in structural cells in two street-revitalization projects in Toronto, Canada, and the impact of this contamination on tree performance. We analyzed soil chemistry and collected tree attributes; these data were examined together to understand the effect of salinity on tree mortality rates and foliar condition. Data collected from continuous soil salinity loggers from April to June for one of the two sites were used to determine whether there was a long-term accumulation of salts in the soils. Results for both sites indicate that both sites displayed high salinity and alkalinity, with levels elevated beyond those suggested before those reported to cause negative tree effects. For one site, trees that were alive and trees that had a better foliar condition had significantly lower levels of soil salinity and alkalinity than other trees. High salinity and alkalinity in the soil were also associated with lower nutrient levels for both sites. Although tests for salinity accumulation in the soils of one site were negative, a longer monitoring of the soil conditions within the soil cells is warranted. Despite structural cells being increasingly utilized for their dual role in storm-water management and tree establishment, there may be a considerable trade-off between storm-water management and urban-forest function in northern climates where de-icing salt application continues to be commonplace. Copyright © 2017 Elsevier Ltd. All rights reserved.

Molecular mechanisms of foliar water uptake in a desert tree

PubMed Central

Yan, Xia; Zhou, Maoxian; Dong, Xicun; Zou, Songbing; Xiao, Honglang; Ma, Xiao-Fei

2015-01-01

Water deficits severely affect growth, particularly for the plants in arid and semiarid regions of the world. In addition to precipitation, other subsidiary water, such as dew, fog, clouds and small rain showers, may also be absorbed by leaves in a process known as foliar water uptake. With the severe scarcity of water in desert regions, this process is increasingly becoming a necessity. Studies have reported on physical and physiological processes of foliar water uptake. However, the molecular mechanisms remain less understood. As major channels for water regulation and transport, aquaporins (AQPs) are involved in this process. However, due to the regulatory complexity and functional diversity of AQPs, their molecular mechanism for foliar water uptake remains unclear. In this study, Tamarix ramosissima, a tree species widely distributed in desert regions, was investigated for gene expression patterns of AQPs and for sap flow velocity. Our results suggest that the foliar water uptake of T. ramosissima occurs in natural fields at night when the humidity is over a threshold of 85 %. The diurnal gene expression pattern of AQPs suggests that most AQP gene expressions display a circadian rhythm, and this could affect both photosynthesis and transpiration. At night, the PIP2-1 gene is also upregulated with increased relative air humidity. This gene expression pattern may allow desert plants to regulate foliar water uptake to adapt to extreme drought. This study suggests a molecular basis of foliar water uptake in desert plants. PMID:26567212

Molecular mechanisms of foliar water uptake in a desert tree.

PubMed

Yan, Xia; Zhou, Maoxian; Dong, Xicun; Zou, Songbing; Xiao, Honglang; Ma, Xiao-Fei

2015-11-12

Water deficits severely affect growth, particularly for the plants in arid and semiarid regions of the world. In addition to precipitation, other subsidiary water, such as dew, fog, clouds and small rain showers, may also be absorbed by leaves in a process known as foliar water uptake. With the severe scarcity of water in desert regions, this process is increasingly becoming a necessity. Studies have reported on physical and physiological processes of foliar water uptake. However, the molecular mechanisms remain less understood. As major channels for water regulation and transport, aquaporins (AQPs) are involved in this process. However, due to the regulatory complexity and functional diversity of AQPs, their molecular mechanism for foliar water uptake remains unclear. In this study, Tamarix ramosissima, a tree species widely distributed in desert regions, was investigated for gene expression patterns of AQPs and for sap flow velocity. Our results suggest that the foliar water uptake of T. ramosissima occurs in natural fields at night when the humidity is over a threshold of 85 %. The diurnal gene expression pattern of AQPs suggests that most AQP gene expressions display a circadian rhythm, and this could affect both photosynthesis and transpiration. At night, the PIP2-1 gene is also upregulated with increased relative air humidity. This gene expression pattern may allow desert plants to regulate foliar water uptake to adapt to extreme drought. This study suggests a molecular basis of foliar water uptake in desert plants. Published by Oxford University Press on behalf of the Annals of Botany Company.

Climate and soil salinity in the deserts of Central Asia

NASA Astrophysics Data System (ADS)

Pankova, E. I.; Konyushkova, M. V.

2013-07-01

A comparative analysis of climatic and soil salinity characteristics of the deserts of Central Asia, including deserts of the Turan Depression, the Gobi Desert, and deserts of the Dzungar and Tarim depressions was performed. The climatic characteristics—the degree of aridity, the degree of continentality, and the amount and regime of precipitation—are different in these deserts. No direct relationships between the areas occupied by the automorphic salt-affected soils and the aridity of the climate are observed in the studied regions. In the automorphic landscapes of Asian deserts, the degree and chemistry of the soil salinization and the distribution of salt-affected soils are controlled by the history of the particular territories rather than by their modern climatic conditions. The presence and properties of the salt-bearing rocks and the eolian migration of salts play the most significant role. The deficit of moisture in the modern climate favors the preservation of salt accumulations in places of their origin. The specific features of the climate, including the regime of precipitation, affect the redistribution of salts in the profiles of automorphic salt-affected soils. An increase in the degree of climatic continentality is accompanied by the decrease in the intensity of weathering and initial accumulation of salts. A different situation is observed in the soils of hydromorphic desert landscapes, in which the degree of salinity of the surface horizons and the area occupied by salt-affected soils are directly influenced by the modern climatic conditions.

Mortality, Recruitment and Change of Desert Tree Populations in a Hyper-Arid Environment

PubMed Central

Andersen, Gidske L.; Krzywinski, Knut

2007-01-01

Background Long-term vegetation changes in hyper-arid areas have long been neglected. Mortality, recruitment and change in populations of the ecologically and culturally important and drought persistent Acacia tortilis and Balanites aegyptiaca are therefore estimated in the Eastern Desert of Egypt, and are related to the primary agents of change, water conditions and human intervention. Methodology A change analysis using high-resolution Corona images (1965) in combination with field data (2003) is the basis for recruitment, mortality and change estimates. For assessing the influence of water conditions on patterns in recruitment and survival, different types of generalized linear models are tested. Conclusions The overall trend in population size in that part of the Eastern Desert studied here is negative. At some sites this negative trend is alarming, because the reduction in mature trees is substantial (>50%) at the same time as recruitment is nearly absent. At a few sites there is a positive trend and better recruitment. Frequent observations of sprouting in saplings indicate that this is an important mechanism to increase their persistence. It is the establishment itself that seems to be the main challenge in the recruitment process. There are indications that hydrological variables and surface water in particular can explain some of the observed pattern in mortality, but our results indicate that direct human intervention, i.e., charcoal production, is the main cause of tree mortality in the Eastern Desert. PMID:17299588

Vegetation species diversity inside and outside exclosures in sagebrush, salt desert shrub, and aspen communities

Treesearch

W. A. Laycock; Dale Bartos

1999-01-01

Vegetation was sampled inside and outside eight exclosures in salt desert shrub and sagebrush vegetation types in Southwestern Wyoming and eight exclosures in aspen vegetation in southern Utah. Only species richness has been examined thus far. Five of the eight Wyoming exclosures had an average of 11% more plant species present outside the exclosure than inside.

Hybrid threshold adaptable quantum secret sharing scheme with reverse Huffman-Fibonacci-tree coding.

PubMed

Lai, Hong; Zhang, Jun; Luo, Ming-Xing; Pan, Lei; Pieprzyk, Josef; Xiao, Fuyuan; Orgun, Mehmet A

2016-08-12

With prevalent attacks in communication, sharing a secret between communicating parties is an ongoing challenge. Moreover, it is important to integrate quantum solutions with classical secret sharing schemes with low computational cost for the real world use. This paper proposes a novel hybrid threshold adaptable quantum secret sharing scheme, using an m-bonacci orbital angular momentum (OAM) pump, Lagrange interpolation polynomials, and reverse Huffman-Fibonacci-tree coding. To be exact, we employ entangled states prepared by m-bonacci sequences to detect eavesdropping. Meanwhile, we encode m-bonacci sequences in Lagrange interpolation polynomials to generate the shares of a secret with reverse Huffman-Fibonacci-tree coding. The advantages of the proposed scheme is that it can detect eavesdropping without joint quantum operations, and permits secret sharing for an arbitrary but no less than threshold-value number of classical participants with much lower bandwidth. Also, in comparison with existing quantum secret sharing schemes, it still works when there are dynamic changes, such as the unavailability of some quantum channel, the arrival of new participants and the departure of participants. Finally, we provide security analysis of the new hybrid quantum secret sharing scheme and discuss its useful features for modern applications.

Atrial natriuretic peptide stimulates salt secretion by shark rectal gland by releasing VIP

DOE Office of Scientific and Technical Information (OSTI.GOV)

Silva, P.; Stoff, J.S.; Solomon, R.J.

1987-01-01

Salt secretion by the isolated perfused rectal gland of the spiny dogfish shark, Squalus acanthias, is stimulated by synthetic rat atrial natriuretic peptide (ANP II) as well as extracts of shark heart, but not by 8-bromo-cyclic guanosine 5'-monophosphate. Cardiac peptides have no effect on isolated rectal gland cells or perfused tubules, suggesting that stimulation requires an intact gland. The stimulation of secretion by ANP II is eliminated by maneuvers that block neurotransmitter release. Cardiac peptides stimulate the release of vasoactive intestinal peptide (VIP), known to be present in rectal glands nerves, into the venous effluent of perfused glands in parallelmore » with their stimulation of salt secretion, but the release of VIP induced by ANP II is prevented by perfusion with procaine. VIP was measured by radioimmunoassay. Cardiac peptides thus appear to regulate rectal gland secretion by releasing VIP from neural stores within the gland. It is possible that other physiological effects of these hormones might be explained by an action to enhanced local release of neurotransmitters.« less

Long-distance flights and high-risk breeding by nomadic waterbirds on desert salt lakes.

PubMed

Pedler, Reece D; Ribot, Raoul F H; Bennett, Andrew T D

2018-02-01

Understanding and conserving mobile species presents complex challenges, especially for animals in stochastic or changing environments. Nomadic waterbirds must locate temporary water in arid biomes where rainfall is highly unpredictable in space and time. To achieve this they need to travel over vast spatial scales and time arrival to exploit pulses in food resources. How they achieve this is an enduring mystery.  We investigated these challenges in the colonial-nesting Banded Stilt (Cladorhynchus leucocephalus), a nomadic shorebird of conservation concern. Hitherto, Banded Stilts were hypothesized to have only 1-2 chances to breed during their long lifetime, when flooding rain fills desert salt lakes, triggering mass-hatching of brine shrimp. Over 6 years, we satellite tagged 57 individuals, conducted 21 aerial surveys to detect nesting colonies on 14 Australian desert salt lakes, and analyzed 3 decades of Landsat and MODIS satellite imagery to quantify salt-lake flood frequency and extent. Within days of distant inland rainfall, Banded Stilts flew 1,000-2,000 km to reach flooded salt lakes. On arrival, females laid over half their body weight in eggs. We detected nesting episodes across the species' range at 7 times the frequency reported during the previous 80 years. Nesting colonies of thousands formed following minor floods, yet most were subsequently abandoned when the water rapidly evaporated prior to egg hatching. Satellite imagery revealed twice as many flood events sufficient for breeding-colony initiation as recorded colonies, suggesting that nesting at remote sites has been underdetected. Individuals took risk on uncertain breeding opportunities by responding to frequent minor flood events between infrequent extensive flooding, exemplifying the extreme adaptability and trade-offs of species exploiting unstable environments. The conservation challenges of nest predation by overabundant native gulls and anthropogenic modifications to salt lakes filling

Hybrid threshold adaptable quantum secret sharing scheme with reverse Huffman-Fibonacci-tree coding

PubMed Central

Lai, Hong; Zhang, Jun; Luo, Ming-Xing; Pan, Lei; Pieprzyk, Josef; Xiao, Fuyuan; Orgun, Mehmet A.

2016-01-01

With prevalent attacks in communication, sharing a secret between communicating parties is an ongoing challenge. Moreover, it is important to integrate quantum solutions with classical secret sharing schemes with low computational cost for the real world use. This paper proposes a novel hybrid threshold adaptable quantum secret sharing scheme, using an m-bonacci orbital angular momentum (OAM) pump, Lagrange interpolation polynomials, and reverse Huffman-Fibonacci-tree coding. To be exact, we employ entangled states prepared by m-bonacci sequences to detect eavesdropping. Meanwhile, we encode m-bonacci sequences in Lagrange interpolation polynomials to generate the shares of a secret with reverse Huffman-Fibonacci-tree coding. The advantages of the proposed scheme is that it can detect eavesdropping without joint quantum operations, and permits secret sharing for an arbitrary but no less than threshold-value number of classical participants with much lower bandwidth. Also, in comparison with existing quantum secret sharing schemes, it still works when there are dynamic changes, such as the unavailability of some quantum channel, the arrival of new participants and the departure of participants. Finally, we provide security analysis of the new hybrid quantum secret sharing scheme and discuss its useful features for modern applications. PMID:27515908

Stimulation of Intestinal Cl- Secretion Through CFTR by Caffeine Intake in Salt-Sensitive Hypertensive Rats.

PubMed

Wei, Xiao; Lu, Zongshi; Yang, Tao; Gao, Peng; Chen, Sijiao; Liu, Daoyan; Zhu, Zhiming

2018-03-16

High salt consumption is a major risk factor for hypertension, and sodium homeostasis is regulated by both intestinal sodium absorption and urinary sodium excretion. Chronic caffeine intake has been reported to attenuate salt-sensitive hypertension by promoting urinary sodium excretion; however, its exact role in intestinal sodium absorption remains unknown. Here, we investigated whether and how chronic caffeine consumption antagonizes salt-sensitive hypertension by inhibiting intestinal sodium absorption. Dahl salt-sensitive rats were fed 8% NaCl chow and 0.1% caffeine in their drinking water for 15 days. The blood pressure and fecal sodium content were measured. The effect of caffeine on the movement of Cl- in enterocyte cells was determined with the Ussing chamber assay. Rats that were treated with caffeine displayed significantly lower mean blood pressure and higher fecal sodium content than the controls. Consistent with these findings, caffeine intake decreased fluid absorption by the intestine in the fluid perfusion experiment. Further, the results from the Ussing chamber assay indicated that caffeine promoted Cl- secretion through enterocyte apical cystic fibrosis transmembrane conductance regulator (CFTR), and thus inhibited sodium absorption. Moreover, depletion of cAMP or inhibition of CFTR completely abolished the effect of caffeine on Cl- secretion. The results indicate that chronic caffeine consumption reduces sodium absorption by promoting CFTR-mediated Cl- secretion in the intestine, which contributes to the anti-hypertensive effect of caffeine in salt-sensitive rats. © 2018 The Author(s). Published by S. Karger AG, Basel.

Long term atmospheric deposition as the source of nitrate and other salts in the Atacama Desert, Chile: New evidence from mass-independent oxygen isotopic compositions

USGS Publications Warehouse

Michalski, Greg; Böhlke, J.K.; Thiemens , Mark

2004-01-01

Isotopic analysis of nitrate and sulfate minerals from the nitrate ore fields of the Atacama Desert in northern Chile has shown anomalous 17O enrichments in both minerals. Δ17O values of 14–21 ‰ in nitrate and 0.4 to 4 ‰ in sulfate are the most positive found in terrestrial minerals to date. Modeling of atmospheric processes indicates that the Δ17O signatures are the result of photochemical reactions in the troposphere and stratosphere. We conclude that the bulk of the nitrate, sulfate and other soluble salts in some parts of the Atacama Desert must be the result of atmospheric deposition of particles produced by gas to particle conversion, with minor but varying amounts from sea spray and local terrestrial sources. Flux calculations indicate that the major salt deposits could have accumulated from atmospheric deposition in a period of 200,000 to 2.0 M years during hyper-arid conditions similar to those currently found in the Atacama Desert. Correlations between Δ17O and δ18O in nitrate salts from the Atacama Desert and Mojave Desert, California, indicate varying fractions of microbial and photochemical end-member sources. The photochemical nitrate isotope signature is well preserved in the driest surficial environments that are almost lifeless, whereas the microbial nitrate isotope signature becomes dominant rapidly with increasing moisture, biologic activity, and nitrogen cycling. These isotopic signatures have important implications for paleoclimate, astrobiology, and N cycling studies.

Genome Sequence of Salt-Tolerant Bacillus safensis Strain VK, Isolated from Saline Desert Area of Gujarat, India.

PubMed

Kothari, V V; Kothari, R K; Kothari, C R; Bhatt, V D; Nathani, N M; Koringa, P G; Joshi, C G; Vyas, B R M

2013-09-05

Bacillus safensis strain VK was isolated from the rhizosphere of a cumin plant growing in the saline desert of Radhanpar, Gujarat, India. Here, we provide the 3.68-Mb draft genome sequence of B. safensis VK, which might provide information about the salt tolerance and genes encoding enzymes for the strain's plant growth-promoting potential.

Thar Desert

NASA Image and Video Library

2001-10-22

This ASTER sub-scene covers an area of 12 x 15 km in NW India in the Thar Desert. The sand dunes of the Thar Desert constantly shift and take on new shapes. Located in northwestern India and eastern Pakistan, the desert is bounded on the south by a salt marsh known as the Rann of Kutch, and on the west by the Indus River plain. About 800 kilometers long and about 490 kilometers wide, the desert's terrain is mainly rolling sandhills with scattered growths of shrub and rock outcroppings. Only about 12 to 25 centimeters of rain fall on the desert each year, and temperatures rise as high as 52 degrees Celsius. Much of the population is pastoral, raising sheep for their wool. The image is located at 24.4 degrees north latitude and 69.3 degrees east longitude. http://photojournal.jpl.nasa.gov/catalog/PIA11094

Honeybee Foraging, Nectar Secretion, and Honey Potential of Wild Jujube Trees, Ziziphus nummularia.

PubMed

Alqarni, A S

2015-06-01

Ziziphus trees are of economic importance due to their aggregated value (source of fruits and timber) and are the most important melliferous plants in the Arabian Peninsula. Interaction between honeybees and Ziziphus nummularia was investigated by assessing foraging, flower phenology, nectar secretion, and honey potential. It is demonstrate that both the native Apis mellifera jemenitica Ruttner and the exotic Apis mellifera carnica Pollmann foraged on Z. nummularia flowers. Bee foraging for nectar and pollen was low (2 ± 0.7 workers/200 flowers/3 min) during early morning and increased to a peak in the afternoon (100 ± 15 workers/200 flowers/3 min). Remarkable foraging activity was recorded during high temperature (35°C) and low humidity (20%) conditions. Foraging for nectar collection was more distinct than that for pollen. The flowering of Z. nummularia was gradual, and was characterized by some flowers that opened and secreted nectar early before sunrise, whereas other flowers remained opened until sunrise. The flowers lasted 2 days, with 83% of nectar secreted in the first day. The peak of nectar secretion was recorded at noon under hot and dry conditions. The lowest amount of nectar was secreted during sunrise under mild temperature (24°C) and humidity (31%) conditions. Under optimum conditions, it is assumed that the average sugar mass was 0.321 ± 0.03 mg TSS/flower, while the total sugar mass was 27.65 ± 11 g/tree. The average honey production potential of tested Z. nummularia was approximately 2.998 kg/tree and 749.475 kg/ha in the main flowering season.

In situ detection of microbial respiration in soils and salt flats. [Nevada desert

NASA Technical Reports Server (NTRS)

Tew, R. W.

1973-01-01

Increase in CO2 partial pressures over a desert soil treated with casamino-acids glucose solution correlated with bacterial growth. Few or no increases in numbers of bacteria or CO2 concentrations were noted in similar plots treated with water only or receiving no treatment. Growth in the soil appeared to be severely nutrient limited during the 10 day experiment. Especially rapid growth took place between the third and fifth day, when temperatures ranged from 0 deg. (night) to a maximum of 17.4 deg. (day). Under the conditions of the experiment, intermittent CO2 assay was an insensitive indicator of growth, possibly because of restiction of gas escape by the desert pavement or solution, exchange, or precipitation of carbonate, but more likely because of inefficient sealing of hoods to and below the soil surface. CO2 assay was unable to detect microbial successions. The unpredictable course of these successions, plus unpredictable relative retentions mitigates against assay of organic gases as reliable in situ detection of microbial activity, except perhaps in very alkaline environments such as Owens Lake salts.

Thar Desert

NASA Technical Reports Server (NTRS)

2001-01-01

This ASTER sub-scene covers an area of 12 x 15 km in NW India in the Thar Desert. The sand dunes of the Thar Desert constantly shift and take on new shapes. Located in northwestern India and eastern Pakistan, the desert is bounded on the south by a salt marsh known as the Rann of Kutch, and on the west by the Indus River plain. About 800 kilometers long and about 490 kilometers wide, the desert's terrain is mainly rolling sandhills with scattered growths of shrub and rock outcroppings. Only about 12 to 25 centimeters of rain fall on the desert each year, and temperatures rise as high as 52 degrees Celsius. Much of the population is pastoral, raising sheep for their wool. The image is located at 24.4 degrees north latitude and 69.3 degrees east longitude.

The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

[Effects of thinning on Calligonum arborescens growth and soil water-salt distribution in Tarim Desert Highway shelterbelt, Xinjiang of Northwest China].

PubMed

Zhang, Jian-Guo; Li, Ying-Gang; Xu, Xin-Wen; Lei, Jia-Qiang; Li, Sheng-Yu

2012-09-01

In order to understand the effects of thinning on the growth of Calligonum arborescens and the soil water-salt distribution in Tarim Desert Highway shelterbelt, a thinning experiment was conducted on an aged and declined C. arborescens woodland in a demonstration section of the shelterbelt, with the growth of C. arborescens and the soil water-salt distribution monitored. Thinning had no effects on the phenophase of C. arborescens, but after thinning, the growth of the current year plant height, crown width, ground diameter, and new branch length of reserved trees was larger than that of the control, and the increment was in the order of planting space 2 mx 1 m > 1 m x 1 m > the control, with significant differences among the treatments. The assimilation branch surface area in treatments 2 mx 1 m and 1 m x 1 m were 5.97 m2 and 5.22 m2 per plant, respectively, being significantly larger than the control (3.1 m2 per plant). The soil moisture content in 0-160 cm layer was significantly higher in treatments 2 m x 1 m and 1 mx 1 m than in the control, and increased obviously with thinning intensity. The soil salt content was in the order of control > planting space 1 m x 1 m > 2 m x 1 m, and the differences among the treatments were significant. It was suggested that the best reserved plant density after thinning was planting space 2 m x 1 m.

Bile salt receptor complex activates a pathogenic type III secretion system

DOE PAGES

Li, Peng; Rivera-Cancel, Giomar; Kinch, Lisa N.; ...

2016-07-05

Bile is an important component of the human gastrointestinal tract with an essential role in food absorption and antimicrobial activities. Enteric bacterial pathogens have developed strategies to sense bile as an environmental cue to regulate virulence genes during infection. We discovered that Vibrio parahaemolyticus VtrC, along with VtrA and VtrB, are required for activating the virulence type III secretion system 2 in response to bile salts. The VtrA/VtrC complex activates VtrB in the presence of bile salts. The crystal structure of the periplasmic domains of the VtrA/VtrC heterodimer reveals a β-barrel with a hydrophobic inner chamber. A co-crystal structure ofmore » VtrA/VtrC with bile salt, along with biophysical and mutational analysis, demonstrates that the hydrophobic chamber binds bile salts and activates the virulence network. As part of a family of conserved signaling receptors, VtrA/VtrC provides structural and functional insights into the evolutionarily conserved mechanism used by bacteria to sense their environment.« less

Global transcriptional profiling of Burkholderia pseudomallei under salt stress reveals differential effects on the Bsa type III secretion system

PubMed Central

2010-01-01

Background Burkholderia pseudomallei is the causative agent of melioidosis where the highest reported incidence world wide is in the Northeast of Thailand, where saline soil and water are prevalent. Moreover, recent reports indicate a potential pathogenic role for B. pseudomallei in cystic fibrosis lung disease, where an increased sodium chloride (NaCl) concentration in airway surface liquid has been proposed. These observations raise the possibility that high salinity may represent a favorable niche for B. pseudomallei. We therefore investigated the global transcriptional response of B. pseudomallei to increased salinity using microarray analysis. Results Transcriptome analysis of B. pseudomallei under salt stress revealed several genes significantly up-regulated in the presence of 320 mM NaCl including genes associated with the bsa-derived Type III secretion system (T3SS). Microarray data were verified by reverse transcriptase-polymerase chain reactions (RT-PCR). Western blot analysis confirmed the increased expression and secretion of the invasion-associated type III secreted proteins BipD and BopE in B. pseudomallei cultures at 170 and 320 mM NaCl relative to salt-free medium. Furthermore, salt-treated B. pseudomallei exhibited greater invasion efficiency into the lung epithelial cell line A549 in a manner partly dependent on a functional Bsa system. Conclusions B. pseudomallei responds to salt stress by modulating the transcription of a relatively small set of genes, among which is the bsa locus associated with invasion and virulence. Expression and secretion of Bsa-secreted proteins was elevated in the presence of exogenous salt and the invasion efficiency was enhanced. Our data indicate that salinity has the potential to influence the virulence of B. pseudomallei. PMID:20540813

Regulation of Renin Secretion and Arterial Pressure During Prolonged Baroreflex Activation: Influence of Salt Intake

PubMed Central

Hildebrandt, Drew A.; Irwin, Eric D.; Cates, Adam W.; Lohmeier, Thomas E.

2014-01-01

Chronic electrical activation of the carotid baroreflex produces sustained reductions in sympathetic activity and arterial pressure and is currently being evaluated as antihypertensive therapy for patients with resistant hypertension. However, the influence of variations in salt intake on blood pressure lowering during baroreflex activation has not been determined. As sensitivity of arterial pressure to salt intake is linked to the responsiveness of renin secretion, we determined steady-state levels of arterial pressure and neurohormonal responses in 6 dogs on low, normal, and high salt intakes ( 5, 40, 450 mmol/day, respectively) under control conditions and during a 7-day constant level of baroreflex activation. Under control conditions, there was no difference in mean arterial pressure at low (92±1) and normal (92±2 mmHg) sodium intakes, but pressure increased 9 ±2 mmHg during high salt. Plasma renin activity (2.01±0.23, 0.93±0.20, 0.01±0.01 ng ANGI/mL/hr) and plasma aldosterone (10.3±1.9, 3.5±0.5, 1.7±0.1ng/dL) were inversely related to salt intake, whereas there were no changes in plasma norepinephrine. Although mean arterial pressure (19-22 mmHg) and norepinephrine (20-40%) were lower at all salt intakes during baroreflex activation, neither the changes in pressure nor the absolute values for plasma renin activity or aldosterone in response to salt were different from control conditions. These findings demonstrate that suppression of sympathetic activity by baroreflex activation lowers arterial pressure without increasing renin release and indicate that changes in sympathetic activity are not primary mediators of the effect of salt on renin secretion. Consequently, blood pressure lowering during baroreflex activation is independent of salt intake. PMID:24935941

Restoration of eroded soil in the Sonoran Desert with native leguminous trees using plant growth-promoting microorganisms and limited amounts of compost and water.

PubMed

Bashan, Yoav; Salazar, Bernardo G; Moreno, Manuel; Lopez, Blanca R; Linderman, Robert G

2012-07-15

Restoration of highly eroded desert land was attempted in the southern Sonoran Desert that had lost its natural capacity for self-revegetation. In six field experiments, the fields were planted with three native leguminous trees: mesquite amargo Prosopis articulata, and yellow and blue palo verde Parkinsonia microphylla and Parkinsonia florida. Restoration included inoculation with two of plant growth-promoting bacteria (PGPB; Azospirillum brasilense and Bacillus pumilus), native arbuscular mycorrhizal (AM) fungi, and small quantities of compost. Irrigation was applied, when necessary, to reach a rainy year (300 mm) of the area. The plots were maintained for 61 months. Survival of the trees was marginally affected by all supplements after 30 months, in the range of 60-90%. This variation depended on the plant species, where all young trees were established after 3 months. Plant density was a crucial variable and, in general, low plant density enhanced survival. High planting density was detrimental. Survival significantly declined in trees 61 months after planting. No general response of the trees to plant growth-promoting microorganisms and compost was found. Mesquite amargo and yellow palo verde responded well (height, number of branches, and diameter of the main stem) to inoculation with PGPB, AM fungi, and compost supplementation after three months of application. Fewer positive effects were recorded after 30 months. Blue palo verde did not respond to most treatments and had the lowest survival. Specific plant growth parameters were affected to varying degrees to inoculations or amendments, primarily depending on the tree species. Some combinations of tree/inoculant/amendment resulted in small negative effects or no response when measured after extended periods of time. Using native leguminous trees, this study demonstrated that restoration of severely eroded desert lands was possible. Copyright © 2012 Elsevier Ltd. All rights reserved.

Desert and desertification in Iran

NASA Astrophysics Data System (ADS)

Bahrami, M.

2009-04-01

pavement), Kalut (Yardang), Hoodoo and wind deposited features such as different kinds of sand dunes (Seif, Nebka, Rebdous, Barkhan, Ghourd, Erg) and Loess, most of which exhibit beautiful landscapes suitable for ecotourism and scientific tours. Salt deserts (Kavir or Playas), which rest in the lowest parts of internal depressions, are the most current features in Iran deserts. The most extensive and specific salt deserts are in the course of floods or at the end of them, which consist of fine grained sediments in the lowest parts of the depressions. Many factors have been participated in the formation of salt deserts in Iran, the most important of which, are morphotectonical (such as folding and faulting due to the last epirogenic and orogenic movements), climatical and hydrological (occurred in Quaternary), geological and pedological (such as the presence of Neogene evaporitic formations).

Chemical and behavioral studies of femoral gland secretions in iguanid lizards.

PubMed

Alberts, A C

1993-01-01

Comparative studies on the chemistry and behavioral significance of femoral gland secretions in desert iguanas (Dipsosaurus dorsalis) and green iguanas (Iguana iguana) are reviewed. Field and laboratory studies suggest that femoral gland secretions function in conspecific recognition and range marking. In desert iguanas, secretions are of low volatility and may be detected initially using long-range ultraviolet visual cues. In contrast, green iguana secretions contain a diversity of volatile lipids and appear to be localized by chemoreception. Interspecific differences in femoral gland chemistry may reflect adaptations to the diverse climatic conditions of arid desert and tropical forest environments.

[Effects of the grain size and thickness of dust deposits on soil water and salt movement in the hinterland of the Taklimakan Desert].

PubMed

Sun, Yan-Wei; Li, Sheng-Yu; Xu, Xin-Wen; Zhang, Jian-Guo; Li, Ying

2009-08-01

By using mcirolysimeter, a laboratory simulation experiment was conducted to study the effects of the grain size and thickness of dust deposits on the soil water evaporation and salt movement in the hinterland of the Taklimakan Desert. Under the same initial soil water content and deposition thickness condition, finer-textured (<0.063 mm) deposits promoted soil water evaporation, deeper soil desiccation, and surface soil salt accumulation, while coarse-textured (0.063-2 mm) deposits inhibited soil water evaporation and decreased deeper soil water loss and surface soil salt accumulation. The inhibition effect of the grain size of dust deposits on soil water evaporation had an inflection point at the grain size 0.20 mm, i. e., increased with increasing grain size when the grain size was 0.063-0.20 mm but decreased with increasing grain size when the grain size was > 0.20 mm. With the increasing thickness of dust deposits, its inhibition effect on soil water evaporation increased, and there existed a logarithmic relationship between the dust deposits thickness and water evaporation. Surface soil salt accumulation had a negative correlation with dust deposits thickness. In sum, the dust deposits in study area could affect the stability of arid desert ecosystem.

A lone desert Joshua tree greeted the arrival of Space Shuttle Endeavour at Edwards Air Force Base,

NASA Technical Reports Server (NTRS)

2001-01-01

A lone desert Joshua tree greeted the arrival of Space Shuttle Endeavour at Edwards Air Force Base, California, May 1, 2001. A large drag chute helped slow Endeavour on the runway. After mounting the shuttle on a converted 747 airliner at NASA's Dryden Flight Research Center, Endeavour will be carried back to the Kennedy Space Center for its next mission. Weather in Florida necessitated landing in California.

78 FR 65356 - Notice of Mailing/Street Address Change for the BLM-Utah West Desert District and Salt Lake Field...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-31

...The mailing/street address for the Bureau of Land Management (BLM), West Desert District and Salt Lake Field Offices will be changing from 2370 South 2300 West, Salt Lake City, UT 84119-2022, to 2370 South Decker Lake Blvd., West Valley City, UT 84119-2022. Persons who use a telecommunications device for the deaf (TDD) may call the Federal Information Relay Service (FIRS) at 1-800-877-8339 to leave a message or question for the above individual. The FIRS is available 24 hours a day, seven days a week. Replies are provided during normal business hours.

Desert landscape irrigation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Quinones, R.

1995-06-01

Industrialization can take place in an arid environment if a long term, overall water management program is developed. The general rule to follow is that recharge must equal or exceed use. The main problem encountered in landscape projects is that everyone wants a lush jungle setting, tall shade trees, ferns, with a variety of floral arrangements mixed in. What we want, what we can afford, and what we get are not always the same. Vegetation that requires large quantities of water are not native to any desert. Surprisingly; there are various types of fruit trees, and vegetables that will thrivemore » in the desert. Peaches, plums, nut trees, do well with drip irrigation as well as tomatoes. Shaded berry plans will also do well, the strawberry being one. In summary; if we match our landscape to our area, we can then design our irrigation system to maintain our landscape and grow a variety of vegetation in any arid or semiarid environment. The application of science and economics to landscaping has now come of age.« less

Effect of Tree Species on Enzyme Secretion by the Shiitake Medicinal Mushroom, Lentinus edodes (Agaricomycetes).

PubMed

Plotnikov, Evgeny V; Glukhova, Lubov B; Sokolyanskaya, Ludmila O; Karnachuk, Olga V; Solioz, Marc

2016-01-01

We compared cold and hot wood extracts of 3 endemic Siberian trees-namely, Prunus padus (bird cherry), Populus tremula (aspen), and Betula sp. (birch)-on biomass production and laccase and peroxidase secretion in submerged cultures by the medicinal mushroom Lentinus edodes. Of the conditions tested, only hot Prunus extracts stimulated biomass production, whereas all extracts stimulated laccase and peroxidase secretion, albeit to different extents. A large, differential stimulation of manganese peroxidase was observed by hot Prunus extracts. The results highlight important differences between tree species in the stimulation of biomass and enzyme production by L. edodes and point to potentially interesting stimulatory factors present in hot Prunus extracts. These findings are of relevance in the use of L. edodes for medicinal or biotechnological applications.

Aquaporins in desert rodent physiology.

PubMed

Pannabecker, Thomas L

2015-08-01

Desert rodents face a sizeable challenge in maintaining salt and water homeostasis due to their life in an arid environment. A number of their organ systems exhibit functional characteristics that limit water loss above that which occurs in non-desert species under similar conditions. These systems include renal, pulmonary, gastrointestinal, nasal, and skin epithelia. The desert rodent kidney preserves body water by producing a highly concentrated urine that reaches a maximum osmolality nearly three times that of the common laboratory rat. The precise mechanism by which urine is concentrated in any mammal is unknown. Insights into the process may be more apparent in species that produce highly concentrated urine. Aquaporin water channels play a fundamental role in water transport in several desert rodent organ systems. The role of aquaporins in facilitating highly effective water preservation in desert rodents is only beginning to be explored. The organ systems of desert rodents and their associated AQPs are described. © 2015 Marine Biological Laboratory.

Thermophilic bacteria in Moroccan hot springs, salt marshes and desert soils.

PubMed

Aanniz, Tarik; Ouadghiri, Mouna; Melloul, Marouane; Swings, Jean; Elfahime, Elmostafa; Ibijbijen, Jamal; Ismaili, Mohamed; Amar, Mohamed

2015-06-01

The diversity of thermophilic bacteria was investigated in four hot springs, three salt marshes and 12 desert sites in Morocco. Two hundred and forty (240) thermophilic bacteria were recovered, identified and characterized. All isolates were Gram positive, rod-shaped, spore forming and halotolerant. Based on BOXA1R-PCR and 16S rRNA gene sequencing, the recovered isolates were dominated by the genus Bacillus (97.5%) represented by B. licheniformis (119), B. aerius (44), B. sonorensis (33), B. subtilis (subsp. spizizenii (2) and subsp. inaquosurum (6)), B. amyloliquefaciens (subsp. amyloliquefaciens (4) and subsp. plantarum (4)), B. tequilensis (3), B. pumilus (3) and Bacillus sp. (19). Only six isolates (2.5%) belonged to the genus Aeribacillus represented by A. pallidus (4) and Aeribacillus sp. (2). In this study, B. aerius and B. tequilensis are described for the first time as thermophilic bacteria. Moreover, 71.25%, 50.41% and 5.41% of total strains exhibited high amylolytic, proteolytic or cellulolytic activity respectively.

Thermophilic bacteria in Moroccan hot springs, salt marshes and desert soils

PubMed Central

Aanniz, Tarik; Ouadghiri, Mouna; Melloul, Marouane; Swings, Jean; Elfahime, Elmostafa; Ibijbijen, Jamal; Ismaili, Mohamed; Amar, Mohamed

2015-01-01

The diversity of thermophilic bacteria was investigated in four hot springs, three salt marshes and 12 desert sites in Morocco. Two hundred and forty (240) thermophilic bacteria were recovered, identified and characterized. All isolates were Gram positive, rod-shaped, spore forming and halotolerant. Based on BOXA1R-PCR and 16S rRNA gene sequencing, the recovered isolates were dominated by the genus Bacillus (97.5%) represented by B. licheniformis (119), B. aerius (44), B. sonorensis (33), B. subtilis (subsp. spizizenii (2) and subsp. inaquosurum (6)), B. amyloliquefaciens (subsp. amyloliquefaciens (4) and subsp. plantarum (4)), B. tequilensis (3), B. pumilus (3) and Bacillus sp. (19). Only six isolates (2.5%) belonged to the genus Aeribacillus represented by A. pallidus (4) and Aeribacillus sp. (2). In this study, B. aerius and B. tequilensis are described for the first time as thermophilic bacteria. Moreover, 71.25%, 50.41% and 5.41% of total strains exhibited high amylolytic, proteolytic or cellulolytic activity respectively. PMID:26273259

Reproductive ecology and stand structure of Joshua tree forests across climate gradients of the Mojave Desert.

PubMed

St Clair, Samuel B; Hoines, Joshua

2018-01-01

Climate change is restructuring plant populations and can result in range shifts depending on responses at various life stages of plants. In 2013, a widespread and episodic flowering event provided an opportunity to characterize how Joshua tree's reproductive success and population structure vary in response to the climate variability across its range. We examined the reproductive success and stand structure of 10 Joshua tree populations distributed across the Mojave Desert. Joshua tree density varied by more than an order of magnitude across sites. At 8 of the 10 sites, nearly 80% of the Joshua trees were in bloom, and at the other two 40% were in bloom. The range of seed production and fruit set across the study populations varied by more than an order of magnitude. Fruit production occurred at all of our study sites suggesting that yucca moth pollinators were present at our sites. Increasing temperature had strong positive correlations with the number of trees in bloom (R2 = 0.42), inflorescences per tree (R2 = 0.37), and fruit mass (R2 = 0.77) and seed size (R2 = 0.89. In contrast, temperature was negatively correlated with Joshua tree stand density (R2 = -0.80). Positive correlations between temperature and greater flower and seed production suggest that warming may positively affect Joshua Tree reproduction while negative relationships between temperature and stand density are suggestive of potential constraints of warmer temperatures on establishment success.

Remote Sensing Field Guide - Desert

DTIC Science & Technology

1991-09-01

rcatching on fire. Caution is advised against thorns on acacia trees, spikey Spinifex n•shes, and several different types of venomous snakes, as well as...e.g., mesquite, many acacias, Spinifex . DESERT PROCESSES WORKING GROUP PATTERN INDICATOR SHFET - DESERT DUNES PHOTOS: GROUND VEGETATION MOUNDS LOCATION...deliberate burning of natural vegetation is done episodically by the abo- rginal inhabitants. They burn the mature vegetation (primarily Spinifex ), which is

Salt Tolerance and Polyphyly in the Cyanobacterium Chroococcidiopsis (Pleurocapsales)1

NASA Technical Reports Server (NTRS)

Cumbers, John Robert; Rothschild, Lynn J.

2014-01-01

Chroococcidiopsis Geitler (Geitler 1933) is a genus of cyanobacteria containing desiccation and radiation resistant species. Members of the genus live in habitats ranging from hot and cold deserts to fresh and saltwater environments. Morphology and cell division pattern have historically been used to define the genus. To better understand the genetic and phenotypic diversity of the genus, 15 species were selected that had been previously isolated from different locations, including salt and freshwater environments. Four markers were sequenced from these 15 species, the 16S rRNA, rbcL, desC1 and gltX genes. Phylogenetic trees were generated which identified two distinct clades, a salt-tolerant clade and a freshwater clade. This study demonstrates that the genus is polyphyletic based on saltwater and freshwater phenotypes. To understand the resistance to salt in more details, species were grown on a range of sea salt concentrations which demonstrated that the freshwater species were salt-intolerant whilst the saltwater species required salt for growth. This study shows an increased resolution of the phylogeny of Chroococcidiopsis and provides further evidence that the genus is polyphyletic and should be reclassified to improve clarity in the literature.

Desert wildfire and severe drought diminish survivorship of the long-lived Joshua Tree (Yucca brevifolia; Agavaceae)

USGS Publications Warehouse

DeFalco, L.A.; Esque, T.C.; Scoles-Sciulla, S. J.; Rodgers, J.

2010-01-01

Extreme climate events are transforming plant communities in the desert Southwest of the United States. Abundant precipitation in 1998 associated with El Ni??o Southern Oscillation (ENSO) stimulated exceptional alien annual plant production in the Mojave Desert that fueled wildfires in 1999. Exacerbated by protracted drought, 80% of the burned Yucca brevifolia, a long-lived arborescent monocot, and 26% of unburned plants died at Joshua Tree National Park by 2004. Many burned plants < 1 m tall died immediately, and survival of all but the tallest, oldest plants declined to the same low level by 2004. Postfire sprouting prolonged survival, but only at the wetter, high-elevation sites. During succeeding dry years, herbaceous plants were scarce, and individuals of Thomomys bottae (pocket gopher) gnawed the periderm and hollowed stems of Y. brevifolia causing many of them to topple. Thomomys bottae damage reduced plant survivorship at low-elevation, unburned sites and diminished survival of burned plants in all but the driest site, which already had low survival. Accentuated ENSO episodes and more frequent wildfires are expected for the desert Southwest and will likely shift Y. brevifolia population structure toward tall, old adults with fewer opportunities for plant recruitment, thus imperiling the persistence of this unique plant community.

Reproductive ecology and stand structure of Joshua tree forests across climate gradients of the Mojave Desert

PubMed Central

Hoines, Joshua

2018-01-01

Climate change is restructuring plant populations and can result in range shifts depending on responses at various life stages of plants. In 2013, a widespread and episodic flowering event provided an opportunity to characterize how Joshua tree’s reproductive success and population structure vary in response to the climate variability across its range. We examined the reproductive success and stand structure of 10 Joshua tree populations distributed across the Mojave Desert. Joshua tree density varied by more than an order of magnitude across sites. At 8 of the 10 sites, nearly 80% of the Joshua trees were in bloom, and at the other two 40% were in bloom. The range of seed production and fruit set across the study populations varied by more than an order of magnitude. Fruit production occurred at all of our study sites suggesting that yucca moth pollinators were present at our sites. Increasing temperature had strong positive correlations with the number of trees in bloom (R2 = 0.42), inflorescences per tree (R2 = 0.37), and fruit mass (R2 = 0.77) and seed size (R2 = 0.89. In contrast, temperature was negatively correlated with Joshua tree stand density (R2 = -0.80). Positive correlations between temperature and greater flower and seed production suggest that warming may positively affect Joshua Tree reproduction while negative relationships between temperature and stand density are suggestive of potential constraints of warmer temperatures on establishment success. PMID:29474414

Seedling establishment in a masting desert shrub parallels the pattern for forest trees

NASA Astrophysics Data System (ADS)

Meyer, Susan E.; Pendleton, Burton K.

2015-05-01

The masting phenomenon along with its accompanying suite of seedling adaptive traits has been well studied in forest trees but has rarely been examined in desert shrubs. Blackbrush (Coleogyne ramosissima) is a regionally dominant North American desert shrub whose seeds are produced in mast events and scatter-hoarded by rodents. We followed the fate of seedlings in intact stands vs. small-scale disturbances at four contrasting sites for nine growing seasons following emergence after a mast year. The primary cause of first-year mortality was post-emergence cache excavation and seedling predation, with contrasting impacts at sites with different heteromyid rodent seed predators. Long-term establishment patterns were strongly affected by rodent activity in the weeks following emergence. Survivorship curves generally showed decreased mortality risk with age but differed among sites even after the first year. There were no detectable effects of inter-annual precipitation variability or site climatic differences on survival. Intraspecific competition from conspecific adults had strong impacts on survival and growth, both of which were higher on small-scale disturbances, but similar in openings and under shrub crowns in intact stands. This suggests that adult plants preempted soil resources in the interspaces. Aside from effects on seedling predation, there was little evidence for facilitation or interference beneath adult plant crowns. Plants in intact stands were still small and clearly juvenile after nine years, showing that blackbrush forms cohorts of suppressed plants similar to the seedling banks of closed forests. Seedling banks function in the absence of a persistent seed bank in replacement after adult plant death (gap formation), which is temporally uncoupled from masting and associated recruitment events. This study demonstrates that the seedling establishment syndrome associated with masting has evolved in desert shrublands as well as in forests.

Effects of salt secretion on psychrometric determinations of water potential of cotton leaves.

PubMed

Klepper, B; Barrs, H D

1968-07-01

Thermocouple psychrometers gave lower estimates of water potential of cotton leaves than did a pressure chamber. This difference was considerable for turgid leaves, but progressively decreased for leaves with lower water potentials and fell to zero at water potentials below about -10 bars. The conductivity of washings from cotton leaves removed from the psychrometric equilibration chambers was related to the magnitude of this discrepancy in water potential, indicating that the discrepancy is due to salts on the leaf surface which make the psychrometric estimates too low. This error, which may be as great as 400 to 500%, cannot be eliminated by washing the leaves because salts may be secreted during the equilibration period. Therefore, a thermocouple psychrometer is not suitable for measuring the water potential of cotton leaves when it is above about -10 bars.

Extrafloral nectar fuels ant life in deserts.

PubMed

Aranda-Rickert, Adriana; Diez, Patricia; Marazzi, Brigitte

2014-11-07

Interactions mediated by extrafloral nectary (EFN)-bearing plants that reward ants with a sweet liquid secretion are well documented in temperate and tropical habitats. However, their distribution and abundance in deserts are poorly known. In this study, we test the predictions that biotic interactions between EFN plants and ants are abundant and common also in arid communities and that EFNs are only functional when new vegetative and reproductive structures are developing. In a seasonal desert of northwestern Argentina, we surveyed the richness and phenology of EFN plants and their associated ants and examined the patterns in ant-plant interaction networks. We found that 25 ant species and 11 EFN-bearing plant species were linked together through 96 pairs of associations. Plants bearing EFNs were abundant, representing ca. 19 % of the species encountered in transects and 24 % of the plant cover. Most ant species sampled (ca. 77 %) fed on EF nectar. Interactions showed a marked seasonal pattern: EFN secretion was directly related to plant phenology and correlated with the time of highest ant ground activity. Our results reveal that EFN-mediated interactions are ecologically relevant components of deserts, and that EFN-bearing plants are crucial for the survival of desert ant communities. Published by Oxford University Press on behalf of the Annals of Botany Company.

Extrafloral nectar fuels ant life in deserts

PubMed Central

Aranda-Rickert, Adriana; Diez, Patricia; Marazzi, Brigitte

2014-01-01

Interactions mediated by extrafloral nectary (EFN)-bearing plants that reward ants with a sweet liquid secretion are well documented in temperate and tropical habitats. However, their distribution and abundance in deserts are poorly known. In this study, we test the predictions that biotic interactions between EFN plants and ants are abundant and common also in arid communities and that EFNs are only functional when new vegetative and reproductive structures are developing. In a seasonal desert of northwestern Argentina, we surveyed the richness and phenology of EFN plants and their associated ants and examined the patterns in ant–plant interaction networks. We found that 25 ant species and 11 EFN-bearing plant species were linked together through 96 pairs of associations. Plants bearing EFNs were abundant, representing ca. 19 % of the species encountered in transects and 24 % of the plant cover. Most ant species sampled (ca. 77 %) fed on EF nectar. Interactions showed a marked seasonal pattern: EFN secretion was directly related to plant phenology and correlated with the time of highest ant ground activity. Our results reveal that EFN-mediated interactions are ecologically relevant components of deserts, and that EFN-bearing plants are crucial for the survival of desert ant communities. PMID:25381258

Examining Basin-Scale Water and Climate Relations across the Pampa del Tamarugal, Atacama Desert through Spatial Analysis of Hydrogen, Carbon and Oxygen Isotopes in Tree Rings

NASA Astrophysics Data System (ADS)

Olson, E. J.; Dodd, J. P.; Rivera, M. A.

2016-12-01

Arid regions are extremely sensitive to variations hydroclimate. However, our understanding of past hydroclimate variations in these regions is often limited by a paucity of spatially resolved proxy data. The Atacama Desert of northern Chile is one of the driest regions on Earth, and hydroclimatic processes in the Atacama Desert may be a useful proxy for understanding the implications of expanding global aridity. In order to assess the ability of tree-ring isotope studies to record changes in hydrology and terrestrial climate in the Atacama Desert, oxygen (δ18O), carbon (δ13C) and hydrogen (δ2H) isotope values in tree rings of Prosopis tamarugo are analyzed for the modern period (1954-2014) when anthropogenic change to regional groundwater levels have been most notable. Samples of wood cellulose were collected throughout the Pampa del Tamarugal basin from 14 individuals and used to create an interpolated surface of isotope variations. The isotope data were then compared to groundwater depth from well monitoring data provided by the Dirección de General de Agua of Chile. There is a significant correlation between groundwater level and isotope values with best agreement occurring during the past two decades for δ18O (r = 0.58), δ13C (r = 0.55), and δ2H (r = 0.66) values. This spatial correlation analysis reveals that tree ring a-cellulose isotope values are a suitable proxy for reconstructing groundwater depth in the Pampa del Tamarugal Basin. A stepwise multiregression analysis between δ18O values of cellulose and several other environmental variables including groundwater level, relative humidity, and temperature suggest that groundwater depth is the dominate control of variation in the modern δ18O tree ring record. The response of tree cellulose to the hydroclimate in this region suggests that tree ring isotope variations may be used to reconstruct past hydroclimate conditions in arid regions throughout the globe.

Effects of Salt Secretion on Psychrometric Determinations of Water Potential of Cotton Leaves

PubMed Central

Klepper, Betty; Barrs, H. D.

1968-01-01

Thermocouple psychrometers gave lower estimates of water potential of cotton leaves than did a pressure chamber. This difference was considerable for turgid leaves, but progressively decreased for leaves with lower water potentials and fell to zero at water potentials below about −10 bars. The conductivity of washings from cotton leaves removed from the psychrometric equilibration chambers was related to the magnitude of this discrepancy in water potential, indicating that the discrepancy is due to salts on the leaf surface which make the psychrometric estimates too low. This error, which may be as great as 400 to 500%, cannot be eliminated by washing the leaves because salts may be secreted during the equilibration period. Therefore, a thermocouple psychrometer is not suitable for measuring the water potential of cotton leaves when it is above about −10 bars. PMID:16656895

Demographic studies of Joshua trees in Mojave Desert National Parks: demography with emphasis on germination and recruitment

USGS Publications Warehouse

Esque, T.C.; Reynolds, B.; DeFalco, L.A.; Waitman, B.A.; Hughson, Debra

2010-01-01

The study of population change with regard to reproduction, seed dispersal, and germination, establishment, growth, and survival/mortality is known as demography. Demographic studies provide managers with information to assess future trends on the density, distribution, health, and population changes of importance or value, including Joshua trees (Yucca brevifolia). Demographic research provides the potential to understand the combined impacts of climate change and land-use practices and determine if strategies for protecting important species are likely to succeed or fall short of management goals and will identify factors that have the potential to de-stabilize populations outside the realm of natural variation so that management strategies can be developed to circumvent challenges for key species, processes, and ecosystems. The National Park Service and US Geological Survey are collaborating to collect demographic information about the demographics of Joshua tree in the Mojave Desert.

Genome-wide Identification of WRKY Genes in the Desert Poplar Populus euphratica and Adaptive Evolution of the Genes in Response to Salt Stress.

PubMed

Ma, Jianchao; Lu, Jing; Xu, Jianmei; Duan, Bingbing; He, Xiaodong; Liu, Jianquan

2015-01-01

WRKY transcription factors play important roles in plant development and responses to various stresses in plants. However, little is known about the evolution of the WRKY genes in the desert poplar species Populus euphratica, which is highly tolerant of salt stress. In this study, we identified 107 PeWRKY genes from the P. euphratica genome and examined their evolutionary relationships with the WRKY genes of the salt-sensitive congener Populus trichocarpa. Ten PeWRKY genes are specific to P. euphratica, and five of these showed altered expression under salt stress. Furthermore, we found that two pairs of orthologs between the two species showed evidence of positive evolution, with dN/dS ratios>1 (nonsynonymous/synonymous substitutions), and both of them altered their expression in response to salinity stress. These findings suggested that both the development of new genes and positive evolution in some orthologs of the WRKY gene family may have played an important role in the acquisition of high salt tolerance by P. euphratica.

Characterization of salt-adapted secreted lignocellulolytic enzymes from the mangrove fungus Pestalotiopsis sp.

PubMed

Arfi, Yonathan; Chevret, Didier; Henrissat, Bernard; Berrin, Jean-Guy; Levasseur, Anthony; Record, Eric

2013-01-01

Fungi are important for biomass degradation processes in mangrove forests. Given the presence of sea water in these ecosystems, mangrove fungi are adapted to high salinity. Here we isolate Pestalotiopsis sp. NCi6, a halotolerant and lignocellulolytic mangrove fungus of the order Xylariales. We study its lignocellulolytic enzymes and analyse the effects of salinity on its secretomes. De novo transcriptome sequencing and assembly indicate that this fungus possesses of over 400 putative lignocellulolytic enzymes, including a large fraction involved in lignin degradation. Proteomic analyses of the secretomes suggest that the presence of salt modifies lignocellulolytic enzyme composition, with an increase in the secretion of xylanases and cellulases and a decrease in the production of oxidases. As a result, cellulose and hemicellulose hydrolysis is enhanced but lignin breakdown is reduced. This study highlights the adaptation to salt of mangrove fungi and their potential for biotechnological applications.

Breeding biology and nest-site selection of red-tailed hawks in an altered desert grassland

USGS Publications Warehouse

Hobbs, R.J.; DeStefano, S.; Halvorson, W.L.

2006-01-01

Red-tailed Hawks (Buteo jamaicensis) have expanded their range as trees have invaded formerly-open grasslands. Desert grasslands of southern Arizona have been invaded by mesquite trees (Prosopis velutina) since Anglo-American settlement and now support a large population of Red-tailed Hawks. We studied a population of Red-tailed Hawks in an altered desert grassland in southern Arizona. Our objectives were to determine what environmental characteristics influence Red-tailed Hawk habitat selection in mesquite-invaded desert grasslands and to evaluate the habitat quality of these grasslands for Red-tailed Hawks based on nesting density, nest success, and productivity. Red-tailed Hawks had 86% (95% C.I. = 73-99) nest success and 1.82 young per breeding pair (95% C.I. = 1.41-2.23). Nesting density was 0.15 (95% CI = 0.08-0.21) breeding pairs/km2 and the mean nearest-neighbor distance was 1.95 km (95% C.I. = 1.74-2.16). Red-tailed Hawks selected nest-sites with taller nest-trees and greater tree height and cover than were available at random. Mesquite trees in desert grasslands provide abundant potential nesting structures for Red-tailed Hawks. ?? 2006 The Raptor Research Foundation, Inc.

A lone desert Joshua tree greeted the arrival of Space Shuttle Endeavour at Edwards Air Force Base, California, on May 1, 2001

NASA Image and Video Library

2001-05-01

A lone desert Joshua tree greeted the arrival of Space Shuttle Endeavour at Edwards Air Force Base, California, May 1, 2001. A large drag chute helped slow Endeavour on the runway. After mounting the shuttle on a converted 747 airliner at NASA's Dryden Flight Research Center, Endeavour will be carried back to the Kennedy Space Center for its next mission. Weather in Florida necessitated landing in California.

Geology and geochemistry of the Atacama Desert.

PubMed

Tapia, J; González, R; Townley, B; Oliveros, V; Álvarez, F; Aguilar, G; Menzies, A; Calderón, M

2018-02-14

The Atacama Desert, the driest of its kind on Earth, hosts a number of unique geological and geochemical features that make it unlike any other environment on the planet. Considering its location on the western border of South America, between 17 and 28 °S, its climate has been characterized as arid to hyperarid for at least the past 10 million years. Notably dry climatic conditions of the Atacama Desert have been related to uplift of the Andes and are believed to have played an important role in the development of the most distinctive features of this desert, including: (i) nitrates and iodine deposits in the Central Depression, (ii) secondary enrichment in porphyry copper deposits in the Precordillera, (iii) Li enrichment in salt flats of the Altiplano, and (iv) life in extreme habitats. The geology and physiography of the Atacama Desert have been largely shaped by the convergent margin present since the Mesozoic era. The geochemistry of surface materials is related to rock geochemistry (Co, Cr, Fe, Mn, V, and Zn), salt flats, and evaporite compositions in endorheic basins (As, B, and Li), in addition to anthropogenic activities (Cu, Mo, and Pb). The composition of surface water is highly variable, nonetheless in general it presents a circumneutral pH with higher conductivity and total dissolved solids in brines. Major water constituents, with the exception of HCO 3 - , are generally related to the increase of salinity, and despite the fact that trace elements are not well-documented, surface waters of the Atacama Desert are enriched in As, B, and Li when compared to the average respective concentrations in rivers worldwide.

Introduction and domestication of woody plants for sustainable agriculture in desert areas

NASA Astrophysics Data System (ADS)

Shelef, Oren; Soloway, Elaine; Rachmilevitch, Shimon

2014-05-01

High radiation in hot deserts results in high salinity, especially in irrigated fields. Whenever not treated properly, this salinization may harm crops and eventually bring to soil destruction, field abandonment, or literally desertification. Furthermore, the range of crops that can be grown commercially in hot deserts is limited (Nerd et al. 1990). With the globalization of the last century, Introduction of exotic species for commercial use became more accessible. However, these attempts may involve extreme land changes including establishment of potential invasive species. Therefore domestication of native species should be preferred rather than introduction of exotics. In the last six years we did first steps of domesticating several native species, searching for commercial potential (pharmaceutics, food, biomass for energy and desalination of constructed wetlands). We studied aspects of desert plant physiology in drought and saline conditions. We wish to share the knowledge we gained regarding the physiology and commercial potential of the following desert plant species: 1) Bassia indica is an annual halophyte. We proposed to use it for salt phytoremediation in constructed wetlands for wastewater treatment and as feed for livestock; 2) Commiphora gileadensis is considered as the balm tree of Judea, praised for its use as holy oil and in perfumes but also considered as a cure for many diseases. C. gileadensis today grows naturally in southwest Arabia and Somaliland. We found anti-proliferative and apoptotic effect of C. gileadensis extracts on several human cancer cells. Ben Gurion University of the Negev has patented these findings. 3) Artemisia sieberi and A. judaica are both known for various therapeutic traits. While studying effects of irrigation intensity on these traits, some allopathic characters were discovered. 4) Fichus palmate disappeared from Israel, but remind in neighbouring Jordan and Egypt. This tree may serve as a robust stand for fig

Investigation of salt loss from the Bonneville Salt Flats, northwestern Utah

USGS Publications Warehouse

Mason, James L.; Kipp, Kenneth L.

1997-01-01

The Bonneville Salt Flats study area is located in the western part of the Great Salt Lake Desert in northwestern Utah, about 110 miles west of Salt Lake City. The salt crust covers about 50 square miles, but the extent varies yearly as a result of salt being dissolved by the formation and movement of surface ponds during the winter and redeposited with the evaporation of these ponds during the summer.A decrease in thickness and extent of the salt crust on the Bonneville Salt Flats has been documented during 1960-88 (S. Brooks, Bureau of Land Management, written commun., 1989). Maximum salt-crust thickness was 7 feet in 1960 and 5.5 feet in 1988. No definitive data are available to identify and quantify the processes that cause salt loss. More than 55 million tons of salt are estimated to have been lost from the salt crust during the 28-year period. The Bureau of Land Management needs to know the causes of salt loss to make appropriate management decisions.

Population, desert expanding.

PubMed

1992-01-01

The conditions of desert expansion in the Sahara are highlighted. On the southern border the desert is growing at a rate of 3-6 miles/year. This growth is encroaching on arable land in Ethiopia and Mauritania. The region loses up to 28,000 sq miles/year of farmland. 33% of Africa's fertile land is threatened. Land-use patterns are responsible for the deterioration of the soil. Traditional practices are not effective because the practices are not suitable for permanent farming. Farmers also have stopped environmentally sound practices such as letting the fields remain fallow in order to renew soil fertility. Nomads overgraze areas before moving on. A recent study by the World Bank's Africa Region Office was released; the report details some of the links between rapid population growth, poor agricultural performance, and environmental degradation. Soil conditions are such that valuable topsoil is blow away by the wind because the layer is too thin. Vegetation at the desert's edge is used for cooking purposes or for heating fuel. Tropical and savannah areas are depleted when tree replacement is inadequate. Only 9 trees are planted for every 100 removed. The report emphasized the role of women and children in contributing to population pressure by increased fertility. Women's work load is heavy and children are a help in alleviating some of the burden of domestic and agricultural work. There is hope in meeting demographic, agricultural, food security, and environmental objectives over the next 30 years if the needs of women are met. The needs include access to education for young women, lessening the work loads of women, and decreasing child mortality through improved health care and access to safe water.

Quantitative and qualitative characteristics of cell wall components and prenyl lipids in the leaves of Tilia x euchlora trees growing under salt stress.

PubMed

Milewska-Hendel, Anna; Baczewska, Aneta H; Sala, Katarzyna; Dmuchowski, Wojciech; Brągoszewska, Paulina; Gozdowski, Dariusz; Jozwiak, Adam; Chojnacki, Tadeusz; Swiezewska, Ewa; Kurczynska, Ewa

2017-01-01

The study was focused on assessing the presence of arabinogalactan proteins (AGPs) and pectins within the cell walls as well as prenyl lipids, sodium and chlorine content in leaves of Tilia x euchlora trees. The leaves that were analyzed were collected from trees with and without signs of damage that were all growing in the same salt stress conditions. The reason for undertaking these investigations was the observations over many years that indicated that there are trees that present a healthy appearance and trees that have visible symptoms of decay in the same habitat. Leaf samples were collected from trees growing in the median strip between roadways that have been intensively salted during the winter season for many years. The sodium content was determined using atomic spectrophotometry, chloride using potentiometric titration and poly-isoprenoids using HPLC/UV. AGPs and pectins were determined using immunohistochemistry methods. The immunohistochemical analysis showed that rhamnogalacturonans I (RG-I) and homogalacturonans were differentially distributed in leaves from healthy trees in contrast to leaves from injured trees. In the case of AGPs, the most visible difference was the presence of the JIM16 epitope. Chemical analyses of sodium and chloride showed that in the leaves from injured trees, the level of these ions was higher than in the leaves from healthy trees. Based on chromatographic analysis, four poly-isoprenoid alcohols were identified in the leaves of T. x euchlora. The levels of these lipids were higher in the leaves from healthy trees. The results suggest that the differences that were detected in the apoplast and symplasm may be part of the defensive strategy of T. x euchlora trees to salt stress, which rely on changes in the chemical composition of the cell wall with respect to the pectic and AGP epitopes and an increased synthesis of prenyl lipids.

Quantitative and qualitative characteristics of cell wall components and prenyl lipids in the leaves of Tilia x euchlora trees growing under salt stress

PubMed Central

Milewska-Hendel, Anna; Baczewska, Aneta H.; Sala, Katarzyna; Dmuchowski, Wojciech; Brągoszewska, Paulina; Gozdowski, Dariusz; Jozwiak, Adam; Chojnacki, Tadeusz; Swiezewska, Ewa; Kurczynska, Ewa

2017-01-01

The study was focused on assessing the presence of arabinogalactan proteins (AGPs) and pectins within the cell walls as well as prenyl lipids, sodium and chlorine content in leaves of Tilia x euchlora trees. The leaves that were analyzed were collected from trees with and without signs of damage that were all growing in the same salt stress conditions. The reason for undertaking these investigations was the observations over many years that indicated that there are trees that present a healthy appearance and trees that have visible symptoms of decay in the same habitat. Leaf samples were collected from trees growing in the median strip between roadways that have been intensively salted during the winter season for many years. The sodium content was determined using atomic spectrophotometry, chloride using potentiometric titration and poly-isoprenoids using HPLC/UV. AGPs and pectins were determined using immunohistochemistry methods. The immunohistochemical analysis showed that rhamnogalacturonans I (RG-I) and homogalacturonans were differentially distributed in leaves from healthy trees in contrast to leaves from injured trees. In the case of AGPs, the most visible difference was the presence of the JIM16 epitope. Chemical analyses of sodium and chloride showed that in the leaves from injured trees, the level of these ions was higher than in the leaves from healthy trees. Based on chromatographic analysis, four poly-isoprenoid alcohols were identified in the leaves of T. x euchlora. The levels of these lipids were higher in the leaves from healthy trees. The results suggest that the differences that were detected in the apoplast and symplasm may be part of the defensive strategy of T. x euchlora trees to salt stress, which rely on changes in the chemical composition of the cell wall with respect to the pectic and AGP epitopes and an increased synthesis of prenyl lipids. PMID:28234963

Two new desert Eschscholzia (Papaveraceae) from southwestern North America.

PubMed

Still, Shannon M

2014-01-01

Two new species of Eschscholzia are described. Both are found in the deserts of California and one extends outside the state boundary into Arizona. Eschscholzia androuxii Still, sp. nov. is found mainly in and around Joshua Tree National Park in Riverside and San Bernardino counties. Eschscholzia papastillii Still, sp. nov. is found from the northern Mojave south through Joshua Tree National Park to central Imperial County. Both are annuals found in coarse, sandy soil and have yellow flowers typical of desert Eschscholzia. Eschscholzia papastillii has an expanded receptacular rim similar to that of Eschscholzia californica. Eschscholzia androuxii has anthocyanin bands around the stamen filaments.

Simulated climate effects of desert irrigation geoengineering.

PubMed

Cheng, Wei; Moore, John C; Cao, Long; Ji, Duoying; Zhao, Liyun

2017-04-18

Geoengineering, the deliberate large-scale manipulation of earth's energy balance to counteract global warming, is an attractive proposition for sparsely populated deserts. We use the BNU and UVic Earth system models to simulate the effects of irrigating deserts under the RCP8.5 scenario. Previous studies focused on increasing desert albedo to reduce global warming; in contrast we examine how extending afforestation and ecological projects, that successfully improve regional environments, fair for geoengineering purposes. As expected desert irrigation allows vegetation to grow, with bare soil or grass gradually becoming shrub or tree covered, with increases in terrestrial carbon storage of 90.3 Pg C (UVic-ESCM) - 143.9 Pg C (BNU-ESM). Irrigating global deserts makes the land surface temperature decrease by 0.48 °C and land precipitation increase by 100 mm yr -1 . In the irrigated areas, BNU-ESM simulates significant cooling of up to 4.2 °C owing to the increases in low cloud and latent heat which counteract the warming effect due to decreased surface albedo. Large volumes of water would be required to maintain global desert irrigation, equivalent 10 mm/year of global sea level (BNU-ESM) compensate for evapotranspiration losses. Differences in climate responses between the deserts prompt research into tailored albedo-irrigation schemes.

Simulated climate effects of desert irrigation geoengineering

PubMed Central

Cheng, Wei; Moore, John C.; Cao, Long; Ji, Duoying; Zhao, Liyun

2017-01-01

Geoengineering, the deliberate large-scale manipulation of earth’s energy balance to counteract global warming, is an attractive proposition for sparsely populated deserts. We use the BNU and UVic Earth system models to simulate the effects of irrigating deserts under the RCP8.5 scenario. Previous studies focused on increasing desert albedo to reduce global warming; in contrast we examine how extending afforestation and ecological projects, that successfully improve regional environments, fair for geoengineering purposes. As expected desert irrigation allows vegetation to grow, with bare soil or grass gradually becoming shrub or tree covered, with increases in terrestrial carbon storage of 90.3 Pg C (UVic-ESCM) – 143.9 Pg C (BNU-ESM). Irrigating global deserts makes the land surface temperature decrease by 0.48 °C and land precipitation increase by 100 mm yr−1. In the irrigated areas, BNU-ESM simulates significant cooling of up to 4.2 °C owing to the increases in low cloud and latent heat which counteract the warming effect due to decreased surface albedo. Large volumes of water would be required to maintain global desert irrigation, equivalent 10 mm/year of global sea level (BNU-ESM) compensate for evapotranspiration losses. Differences in climate responses between the deserts prompt research into tailored albedo-irrigation schemes. PMID:28418005

Quaternary geology and geologic hazards of the West Desert Hazardous Industry Area, Tooele County, Utah

USGS Publications Warehouse

Solomon, Barry J.; Black, Bill D.; ,

1990-01-01

The study of Quaternary geology provides information to evaluate geologic conditions and identify geologic constraints on construction in the West Desert Hazardous Industry Area (WDHIA). The WDHIA includes portions of the Great Salt Lake Desert to the west, underlain by several thousand feet of sediments capped by saline mudflats, and Ripple Valley to the east, separated from the Desert by the Grayback Hills and underlain by several hundred feet of sediments in the Cedar Mountains piedmont zone. Quaternary surficial units include marginal, shore-zone, and deep-water lacustrine sediments deposited in Pleistocene Lake Bonneville; eolian deposits; and alluvial sediments. The level of Lake Bonneville underwent major oscillations resulting in the creation of four basin-wide shorelines, three of which are recognized in the WDHIA. Geologic hazards in the WDHIA include the possible contamination of ground water in basin-fill aquifers, debris flows and flash floods in the piedmont zone, and earthquakes and related hazards. Numerous factors contribute to unsafe foundation conditions. Silty and sandy sediments may be subject to liquefaction or hydrocompaction, clayey sediments and mud flats of the Great Salt Lake Desert may be subject to shrinking or swelling, and gypsiferous dunes and salt flats are subject to subsidence due to dissolution.

Quadrulella texcalense sp. nov. from a Mexican desert: An unexpected new environment for hyalospheniid testate amoebae.

PubMed

Pérez-Juárez, Horacio; Serrano-Vázquez, Angélica; Kosakyan, Anush; Mitchell, Edward A D; Rivera Aguilar, Víctor M; Lahr, Daniel J G; Hernández Moreno, Mayra M; Cuellar, Humberto Macías; Eguiarte, Luis E; Lara, Enrique

2017-10-01

Quadrulella (Amoebozoa, Arcellinida, Hyalospheniidae) is a genus of testate amoebae with unmistakable morphology, which secretes characteristic square plates to reinforce the test. They are mainly known from fens and freshwater habitats and have never been documented in deserts. We describe a new species, Quadrulella texcalense, from biological soil crusts in the intertropical desert of Tehuacán (state of Puebla, Mexico). Quadrulella texcalense occurred only at altitudes between 2140 and 2221m.a.s.l., together with the bryophyte genera Pseudocrossidium, Weissia, Bryum, Didymodon, Neohyophyla and Aloina. The soil was extremely dry (moisture of 1.97-2.6%), which contrasts sharply with previous reports for the Quadrulella genus. Single cell mitochondrial cytochrome oxidase I (COI) barcoding of thirteen isolated cells showed an important morphological variability despite having all the same COI barcode sequence. Quadrulella texcalense was placed in a tree containing other Hyalsopheniidae, including a newly barcoded South African species, Q. elegans. Q. texcalense unambiguously branched within genus Quadrulella in a compact clade but with a long branch, suggesting accelerated evolution due to a transition towards a new environment and/or under-sampling. Copyright © 2017 Elsevier GmbH. All rights reserved.

Genomic, transcriptomic, and proteomic approaches towards understanding the molecular mechanisms of salt tolerance in Frankia strains isolated from Casuarina trees.

PubMed

Oshone, Rediet; Ngom, Mariama; Chu, Feixia; Mansour, Samira; Sy, Mame Ourèye; Champion, Antony; Tisa, Louis S

2017-08-18

Soil salinization is a worldwide problem that is intensifying because of the effects of climate change. An effective method for the reclamation of salt-affected soils involves initiating plant succession using fast growing, nitrogen fixing actinorhizal trees such as the Casuarina. The salt tolerance of Casuarina is enhanced by the nitrogen-fixing symbiosis that they form with the actinobacterium Frankia. Identification and molecular characterization of salt-tolerant Casuarina species and associated Frankia is imperative for the successful utilization of Casuarina trees in saline soil reclamation efforts. In this study, salt-tolerant and salt-sensitive Casuarina associated Frankia strains were identified and comparative genomics, transcriptome profiling, and proteomics were employed to elucidate the molecular mechanisms of salt and osmotic stress tolerance. Salt-tolerant Frankia strains (CcI6 and Allo2) that could withstand up to 1000 mM NaCl and a salt-sensitive Frankia strain (CcI3) which could withstand only up to 475 mM NaCl were identified. The remaining isolates had intermediate levels of salt tolerance with MIC values ranging from 650 mM to 750 mM. Comparative genomic analysis showed that all of the Frankia isolates from Casuarina belonged to the same species (Frankia casuarinae). Pangenome analysis revealed a high abundance of singletons among all Casuarina isolates. The two salt-tolerant strains contained 153 shared single copy genes (most of which code for hypothetical proteins) that were not found in the salt-sensitive(CcI3) and moderately salt-tolerant (CeD) strains. RNA-seq analysis of one of the two salt-tolerant strains (Frankia sp. strain CcI6) revealed hundreds of genes differentially expressed under salt and/or osmotic stress. Among the 153 genes, 7 and 7 were responsive to salt and osmotic stress, respectively. Proteomic profiling confirmed the transcriptome results and identified 19 and 8 salt and/or osmotic stress-responsive proteins in the

Salt deposits in Arizona promise gas-storage opportunities

USGS Publications Warehouse

Rauzi, S.L.

2002-01-01

Massive salt formations and their proximity to pipeline systems and power plants make Arizona attractive for natural gas storage. Caverns dissolved in subsurface salt are used to store LPG at Ferrellgas Partners LP facility near Holbrook and the AmeriGas Partners LP facility near Glendale. Three other companies are investigating the feasibility of storing natural gas in Arizona salt: Copper Eagle Gas Storage LLC, Desert Crossing Gas Storage and Transportation System LLC, and Aquila Inc. The most extensive salt deposits are in the Colorado Plateau Province. Marine and nonmarine salt deposits are present in Arizona.

Channel Response to Low-Elevation Desert Fire: The King Valley Fire of 2005

USGS Publications Warehouse

Webb, Robert H.; Griffiths, Peter G.; Wallace, Cynthia S.A.; Boyer, Diane E.

2007-01-01

In late September to early October 2005, a fire swept north from the Yuma Proving Grounds and into the Kofa National Wildlife Refuge (NWR), traveling mainly along desert wash systems and low-relief alluvial fans. This fire burned 9,975 ha, moving through xeroriparian systems in washes as well as low-elevation desert ecosystems in King Valley, a major area of designated wilderness in the southern part of the Kofa NWR. Using satellite imagery, we determined that 9,255 ha of the Kofa NWR in King Valley burned. The fine-fuel loading for the fire was mostly a native forb (Plantago insularis), and the desert environment that was burned was mostly low-cover creosote bush (Larrea tridentata) scrub with scattered palo verde (Cercidium microphyllum). The wash environments had significant tree cover, including ironwood (Olneya tesota), blue palo verde (Cercidium floridum), desert willow (Chilopsis linearis), and/or smoke tree (Psorothamnus spinosa). This report presents monitoring data collected in June 2006 and January-February 2007 on the effects of this fire on channel morphology in King Valley.

Salt tolerance research in date palm tree (Phoenix dactylifera L.), past, present, and future perspectives.

PubMed

Yaish, Mahmoud W; Kumar, Prakash P

2015-01-01

The date palm can adapt to extreme drought, to heat, and to relatively high levels of soil salinity. However, excessive amounts of salt due to irrigation with brackish water lead to a significant reduction in the productivity of the fruits as well as marked decrease in the viable numbers of the date palm trees. It is imperative that the nature of the existing salt-adaptation mechanism be understood in order to develop future date palm varieties that can tolerate excessive soil salinity. In this perspective article, several research strategies, obstacles, and precautions are discussed in light of recent advancements accomplished in this field and the properties of this species. In addition to a physiological characterization, we propose the use of a full range of OMICS technologies, coupled with reverse genetics approaches, aimed toward understanding the salt-adaption mechanism in the date palm. Information generated by these analyses should highlight transcriptional and posttranscriptional modifications controlling the salt-adaptation mechanisms. As an extremophile with a natural tolerance for a wide range of abiotic stresses, the date palm may represent a treasure trove of novel genetic resources for salinity tolerance.

Spatial Patterns of Soil Organic Carbon Relative to Tree Size and Canopy Distribution in a Semi-Desert Grassland

NASA Astrophysics Data System (ADS)

Throop, H. L.; Archer, S.

2004-12-01

The abundance of woody species in grasslands and savannas has increased globally over the past century. Recent estimates suggest that this proliferation of woody plants may account for a significant fraction of the Northern Hemisphere C sink, although a large degree of uncertainty exists in the magnitude and spatial distribution of these plant and soil pools. While field-based inventories have made progress in assessing the role of aboveground woody growth in ecosystem C inventories, the effect of woody proliferation on soil organic carbon (SOC) remains controversial, despite the fact that the majority of ecosystem C in these systems is typically belowground. Elevated levels of SOC underneath woody plant canopies have been widely reported, but little is known about the spatial distribution of SOC relative to tree canopies. Understanding the spatial distribution of SOC is critical, however, to developing accurate landscape-scale assessments of woody proliferation impacts on ecosystem C pools. We quantified the influence of encroaching mesquite trees (Fabaceae: Prosopis velutina) on the concentration of SOC and total nitrogen (TN) in a semi-desert grassland in southern Arizona. SOC concentrations near the boles of large trees (basal diameter 85-102 cm) were approximately double that of SOC in intercanopy zones (0.9% vs. 0.4% SOC by weight). SOC declined moving out from the bole to the canopy edge, at which point it was equivalent to inter-canopy spaces. Small to medium-sized trees (basal diameters less than 85 cm) had minimal influence on SOC concentrations. Patterns of TN values mirrored those of SOC in all cases, although TN values were roughly an order of magnitude lower than SOC values. These data suggest that accurate accounting of landscape-level SOC stocks will require developing area-weighting algorithms that account for tree size and bole-to-canopy gradients.

Hydrologic reconnaissance of the southern Great Salt Lake Desert and summary of the hydrology of west-central Utah

USGS Publications Warehouse

Gates, Joseph S.; Kruer, Stacie A.

1981-01-01

This report is the last of 19 hydrologic reconnaissances of the basins in western Utah. The purposes of this series of studies are (1) to analyze available hydrologic data and describe the hydrologic system, (2) to evaluate existing and potential water-resources development, and (3) to identify additional studies that might be needed. Part 1 of this report gives an estimate of recharge and discharge, an estimate of the potential for water-resources development, and a statement on the quality of water in the southern Great Salt Lake Desert part of west-central Utah. Part 2 deals with the same aspects of west-central Utah as a whole. Part 2 also summarizes the evidence of interbasin ground-water flow in west-central Utah and presents a theory for the origin of the water discharged from Fish Springs.

Testing the reliability of δ13C of tree rings as climate tool in Pistacia khinjuk of Syrian desert

NASA Astrophysics Data System (ADS)

Caracuta, Valentina; Fiorentino, Girolamo

2010-05-01

High-resolution measures of past climate variations have been found to be of a critical importance for understanding anthropic resilience in drought-sensitive areas. The hills (Jebels) Abu-Rujmain and Abd al Aziz, with their 350 millimetre of rain and their steppe-forest spreading in the middle of the flat syrian desert, represent an unicum where analysing the effect of short term climate changes on pastoral communities. Thanks to a cooperation project in Syrian Arab republic with CIHEAM-Mediterranean Agronomic Institute of Bari -Italy (Rationalization of Ras El Ain Irrigation systems), we were allowed to carry out dendroclimate and carbon isotope analyses on tree-rings of local Pistacia khinjuk, a long-lived wood taxon, in order to test their reliability as tool for determining annual and seasonal rainfall/temperature variations. Comparison between the last 25 year rainfall and temperature values of the nearby meteorological stations and dendro-isotopes values have been carried out to point out which factor mostly affect the growth pattern of the trees in that particular area.

Subsurface Salts in Antarctic Dry Valley Soils

NASA Technical Reports Server (NTRS)

Englert, P.; Bishop, J. L.; Gibson, E. K.; Koeberl, C.

2013-01-01

The distribution of water-soluble ions, major and minor elements, and other parameters were examined to determine the extent and effects of chemical weathering on cold desert soils. Patterns at the study sites support theories of multiple salt forming processes, including marine aerosols and chemical weathering of mafic minerals. Periodic solar-mediated ionization of atmospheric nitrogen might also produce high nitrate concentrations found in older sediments. Chemical weathering, however, was the major contributor of salts in Antarctic Dry Valleys. The Antarctic Dry Valleys represent a unique analog for Mars, as they are extremely cold and dry desert environments. Similarities in the climate, surface geology, and chemical properties of the Dry Valleys to that of Mars imply the possible presence of these soil formation mechanisms on Mars, other planets and icy satellites.

Inhibition effect of tea tree oil on Listeria monocytogenes growth and exotoxin proteins listeriolysin O and p60 secretion.

PubMed

Liu, Z; Meng, R; Zhao, X; Shi, C; Zhang, X; Zhang, Y; Guo, N

2016-12-01

Listeria monocytogenes (L. monocytogenes) is a Gram-positive bacterium that causes infections in humans. In this study, the effects of tea tree oil (TTO) at subinhibitory concentrations on L. monocytogenes growth and two important exotoxin proteins secreted by L. monocytogenes were researched. Treatment with half of minimal inhibitory concentration of TTO demonstrated very little or no reduction in numbers of viable ATCC 19115 cells. Listeriolysin O (LLO) and p60, were investigated. A listeriolysin assay was used to investigate the hemolytic activities of L. monocytogenes exposed to TTO, and the secretion of LLO and p60 was detected by immunoblot analysis. Additionally, real-time RT-PCR was used to analyse the influence of TTO on the transcription of LLO and p60 encoded genes hly and iap respectively. According to our experimental results, we propose that TTO could be used as a promising natural compound against L. monocytogenes and its virulence factors. This is the first report on the influence of subinhibitory concentrations of tea tree oil (TTO) on the secretion of listeriolysin O (LLO) and p60, the critical virulence factors involved in Listeria pathogenesis. The results showed that TTO at 0·25 mg ml -1 reduced the secretion of LLO and p60 to 10 and 34·9% respectively, in addtion, the transcription of hly and iap was reduced to 10 and 4·3% at 0·5 mg ml -1 respectively. We propose that TTO could be used as a promising antimicrobial compound and virulence inhibitor against L. monocytogenes. © 2016 The Society for Applied Microbiology.

THE SHARK RECTAL GLAND MODEL: A CHAMPION OF RECEPTOR MEDIATED CHLORIDE SECRETION THROUGH CFTR

PubMed Central

FORREST, JOHN N.

2016-01-01

The dogfish shark salt gland was predicted by Smith and discovered by Burger at the Mount Desert Island Biological Laboratory in Salisbury Cove, Maine. It is an epithelial organ in the intestine composed of tubules that serve a single function: the secretion of hypertonic NaCl. Many G protein receptors are present on the basolateral surface of these tubules, including stimulatory receptors for vasoactive intestinal peptide, adenosine A2, growth hormone releasing hormone, and inhibitory receptors for somatostatin and adenosine A1. An entirely different class of stimulatory receptors is present as C-type natriuretic peptide receptors. Each stimulatory receptor evokes powerful NaCl secretion. G protein receptors bind to Gαs to activate the catalytic unit of adenylate cyclase to form cyclic adenosine monophosphate (cAMP) and protein kinase A that phosphorylates the regulatory domain of cystic fibrosis transmembrane conductance regulator, opening the channel. The C-type natriuretic peptide receptor stimulates by activating guanylate cyclase and endogenous cyclic guanosine monophosphate which inhibits type 3 phosphodiesterase, the enzyme that breaks down cAMP, thereby elevating cAMP and activating the protein kinase A pathway. PMID:28066051

Bile Formation and Secretion

PubMed Central

Boyer, James L.

2014-01-01

Bile is a unique and vital aqueous secretion of the liver that is formed by the hepatocyte and modified down stream by absorptive and secretory properties of the bile duct epithelium. Approximately 5% of bile consists of organic and inorganic solutes of considerable complexity. The bile-secretory unit consists of a canalicular network which is formed by the apical membrane of adjacent hepatocytes and sealed by tight junctions. The bile canaliculi (~1 μm in diameter) conduct the flow of bile countercurrent to the direction of portal blood flow and connect with the canal of Hering and bile ducts which progressively increase in diameter and complexity prior to the entry of bile into the gallbladder, common bile duct, and intestine. Canalicular bile secretion is determined by both bile salt-dependent and independent transport systems which are localized at the apical membrane of the hepatocyte and largely consist of a series of adenosine triphosphate-binding cassette transport proteins that function as export pumps for bile salts and other organic solutes. These transporters create osmotic gradients within the bile canalicular lumen that provide the driving force for movement of fluid into the lumen via aquaporins. Species vary with respect to the relative amounts of bile salt-dependent and independent canalicular flow and cholangiocyte secretion which is highly regulated by hormones, second messengers, and signal transduction pathways. Most determinants of bile secretion are now characterized at the molecular level in animal models and in man. Genetic mutations serve to illuminate many of their functions. PMID:23897680

The role of salinity tolerance and competition in the distribution of an endangered desert salt marsh endemic

USGS Publications Warehouse

DeFalco, Lesley; Scoles, Sara; Beamguard, Emily R.

2017-01-01

Rare plants are often associated with distinctive soil types, and understanding why endemic species occur in unique environments is fundamental for their management. At Ash Meadows National Wildlife Refuge in southern Nevada, USA, we evaluated whether the limited distribution of endangered Amargosa niterwort (Nitrophila mohavensis) is explained by this species’ tolerance of saline soils on salt-encrusted mud flats compared with the broadly distributed desert saltgrass (Distichlis spicata var. stricta). We simultaneously explored whether niterwort distribution is restricted from expanding due to interspecific competition with saltgrass. Surface soils collected throughout niterwort’s range were unexpectedly less saline with lower extractable Na, seasonal electroconductivity, and Na absorption ratio, and higher soil moisture than in adjacent saltgrass or mixed shrub habitats. Comparison of niterwort and saltgrass growth along an experimental salinity gradient in a greenhouse demonstrated lower growth of niterwort at all but the highest NaCl concentrations. Although growth of niterwort ramets was similar when transplanted into both habitats at the refuge below Crystal Reservoir, niterwort reproductive effort was considerably higher in saltgrass compared to its own habitat, implying reallocation of resources to sexual reproduction to maximize fitness when the probability of ramet mortality increases with greater salinity stress. Saltgrass was not a demonstrated direct competitor of niterwort; however, this species is known to increase soil salinity by exuding salt ions and through litterfall. Niterwort conservation will benefit from protecting hydrological processes that reduce salinity stress and preventing saltgrass colonization into niterwort habitat.

Parent material which produces saline outcrops as a factor in differential distribution of perennial plants in the northern Mojave Desert

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wallace, A.; Romney, E.M.; Wood, R.A.

1980-01-01

An area of 0.46 km/sup 2/ divided into six zones in the northern Mojave Desert transitional with the Great Basin Desert has been studied. Diversity is high among the perennial plant species within the 0.46 km/sup 2/ area. Common species for the two deserts that are present in the area studied are Atriplex confertifolia (Torr. and Frem.) S. Wats., Ceratoides lanata (Pursh) J.T. Howell, Grayia spinosa (Hook.) Moq., Ephedra nevadensis S. Wats. Some other species present include Lycium andersonii A. Gray, Lycium pallidum Miers, Ambrosia dumosa (A. Gray) Payne., Larrea tridentata (Sesse and Moc. ex DC) Cov., Acamptopappus shockleyi A.more » Gray, and Krameria parvifolia, Benth. Some of the species are relatively salt tolerant and some are relatively salt sensitive. A total of 4282 individual plants were measured. There was considerable variation in distribution of the 10 dominant species present, apparently due to zonal variations of salinity dispersed within the study area. Correlation coefficients among pairs of the species for different zones illustrate interrelationships among the salt-tolerant and salt-sensitive species. Observations on an adjacent hillside with rock outcroppings indicate that the saline differences in this area are partly due to outcroppings of parent volcanic rock materials that yield Na salts upon weathering.« less

Deserts

USGS Publications Warehouse

Belnap, Jayne; Webb, Robert H.; Esque, Todd; Brooks, Matthew L.; DeFalco, Lesley; MacMahon, James A.

2016-01-01

The deserts of California (Lead photo, Fig. 1) occupy approximately 38% of California’s landscape (Table 1) and consist of three distinct deserts: the Great Basin Desert, Mojave Desert, and Colorado Desert, the latter of which is a subdivision of the Sonoran Desert (Brown and Lowe 1980). The wide range of climates and geology found within each of these deserts result in very different vegetative communities and ecosystem processes and therefore different ecosystem services. In deserts, extreme conditions such as very high and low temperatures and very low rainfall result in abiotic factors (climate, geology, geomorphology, and soils) controlling the composition and function of ecosystems, including plant and animal distributions. This is in contrast to wetter and milder temperatures found in other ecosystems, where biotic interactions are the dominant driving force. However, despite the harsh conditions in deserts, they are home to a surprisingly large number of plants and animals. Deserts are also places where organisms display a wide array of adaptations to the extremes they encounter, providing some of the best examples of Darwinian selection (MacMahon and Wagner 1985, Ward 2009). Humans have utilized these regions for thousands of years, despite the relatively low productivity and harsh climates of these landscapes. Unlike much of California, most of these desert lands have received little high-intensity use since European settlement, leaving large areas relatively undisturbed. Desert landscapes are being altered, however, by the introduction of fire following the recent invasion of Mediterranean annual grasses. As most native plants are not fire-adapted, they Many do not recover, whereas the non-native grasses flourish. Because desert lands are slow to recover from disturbances, energy exploration and development, recreational use, and urban development will alter these landscapes for many years to come. This chapter provides a brief description of where the

Desert Dermatoses (Thar Desert, India).

PubMed

Chatterjee, Col Manas

2017-01-01

Desert dermatology describes the cutaneous changes and the diseases affecting those living in the desert. Diurnal variation in temperature is high and is characteristic of the deserts. The lack of water affects daily activities and impacts dermatological conditions. Adaptation to the desert is, therefore, important to survival. Infections are the most common conditions seen among this population, and among them, fungal infections are the most common. The high incidence of these infections would be accounted for by the poor hygienic conditions due to lack of bathing facilities due to scarcity of water and the consequent sweat retention and overgrowth of cutaneous infective organisms. Pigmentary disorders, photodermatoses, leishmaniasis, and skin tumors are found to be more prevalent in this region. Desert sweat dermatitis was another specific condition found to have an increased incidence. The environment of the desert provides for a wide variety of dermatoses that can result in these regions with few of these dermatoses found in much higher incidence than in other regions.

Desert Dermatoses (Thar Desert, India)

PubMed Central

Chatterjee, Col Manas

2017-01-01

Desert dermatology describes the cutaneous changes and the diseases affecting those living in the desert. Diurnal variation in temperature is high and is characteristic of the deserts. The lack of water affects daily activities and impacts dermatological conditions. Adaptation to the desert is, therefore, important to survival. Infections are the most common conditions seen among this population, and among them, fungal infections are the most common. The high incidence of these infections would be accounted for by the poor hygienic conditions due to lack of bathing facilities due to scarcity of water and the consequent sweat retention and overgrowth of cutaneous infective organisms. Pigmentary disorders, photodermatoses, leishmaniasis, and skin tumors are found to be more prevalent in this region. Desert sweat dermatitis was another specific condition found to have an increased incidence. The environment of the desert provides for a wide variety of dermatoses that can result in these regions with few of these dermatoses found in much higher incidence than in other regions. PMID:28216726

Climate variability over the Holocene in the Atacama Desert of Chile as reconstructed from tree ring isotope series

NASA Astrophysics Data System (ADS)

Olson, Elizabeth; Dodd, Justin; Rivera, Mario

2017-04-01

Holocene ENSO variability in the Western Hemisphere. This study demonstrates the utility of desert tree-ring isotope series in expanding climate records to areas lacking other high-resolution paleoarchives.

Long Non-Coding RNAs Responsive to Salt and Boron Stress in the Hyper-Arid Lluteño Maize from Atacama Desert.

PubMed

Huanca-Mamani, Wilson; Arias-Carrasco, Raúl; Cárdenas-Ninasivincha, Steffany; Rojas-Herrera, Marcelo; Sepúlveda-Hermosilla, Gonzalo; Caris-Maldonado, José Carlos; Bastías, Elizabeth; Maracaja-Coutinho, Vinicius

2018-03-20

Long non-coding RNAs (lncRNAs) have been defined as transcripts longer than 200 nucleotides, which lack significant protein coding potential and possess critical roles in diverse cellular processes. Long non-coding RNAs have recently been functionally characterized in plant stress-response mechanisms. In the present study, we perform a comprehensive identification of lncRNAs in response to combined stress induced by salinity and excess of boron in the Lluteño maize, a tolerant maize landrace from Atacama Desert, Chile. We use deep RNA sequencing to identify a set of 48,345 different lncRNAs, of which 28,012 (58.1%) are conserved with other maize (B73, Mo17 or Palomero), with the remaining 41.9% belonging to potentially Lluteño exclusive lncRNA transcripts. According to B73 maize reference genome sequence, most Lluteño lncRNAs correspond to intergenic transcripts. Interestingly, Lluteño lncRNAs presents an unusual overall higher expression compared to protein coding genes under exposure to stressed conditions. In total, we identified 1710 putatively responsive to the combined stressed conditions of salt and boron exposure. We also identified a set of 848 stress responsive potential trans natural antisense transcripts ( trans -NAT) lncRNAs, which seems to be regulating genes associated with regulation of transcription, response to stress, response to abiotic stimulus and participating of the nicotianamine metabolic process. Reverse transcription-quantitative PCR (RT-qPCR) experiments were performed in a subset of lncRNAs, validating their existence and expression patterns. Our results suggest that a diverse set of maize lncRNAs from leaves and roots is responsive to combined salt and boron stress, being the first effort to identify lncRNAs from a maize landrace adapted to extreme conditions such as the Atacama Desert. The information generated is a starting point to understand the genomic adaptabilities suffered by this maize to surpass this extremely stressed

Long Non-Coding RNAs Responsive to Salt and Boron Stress in the Hyper-Arid Lluteño Maize from Atacama Desert

PubMed Central

Huanca-Mamani, Wilson; Arias-Carrasco, Raúl; Cárdenas-Ninasivincha, Steffany; Rojas-Herrera, Marcelo; Sepúlveda-Hermosilla, Gonzalo; Caris-Maldonado, José Carlos; Bastías, Elizabeth; Maracaja-Coutinho, Vinicius

2018-01-01

Long non-coding RNAs (lncRNAs) have been defined as transcripts longer than 200 nucleotides, which lack significant protein coding potential and possess critical roles in diverse cellular processes. Long non-coding RNAs have recently been functionally characterized in plant stress–response mechanisms. In the present study, we perform a comprehensive identification of lncRNAs in response to combined stress induced by salinity and excess of boron in the Lluteño maize, a tolerant maize landrace from Atacama Desert, Chile. We use deep RNA sequencing to identify a set of 48,345 different lncRNAs, of which 28,012 (58.1%) are conserved with other maize (B73, Mo17 or Palomero), with the remaining 41.9% belonging to potentially Lluteño exclusive lncRNA transcripts. According to B73 maize reference genome sequence, most Lluteño lncRNAs correspond to intergenic transcripts. Interestingly, Lluteño lncRNAs presents an unusual overall higher expression compared to protein coding genes under exposure to stressed conditions. In total, we identified 1710 putatively responsive to the combined stressed conditions of salt and boron exposure. We also identified a set of 848 stress responsive potential trans natural antisense transcripts (trans-NAT) lncRNAs, which seems to be regulating genes associated with regulation of transcription, response to stress, response to abiotic stimulus and participating of the nicotianamine metabolic process. Reverse transcription-quantitative PCR (RT-qPCR) experiments were performed in a subset of lncRNAs, validating their existence and expression patterns. Our results suggest that a diverse set of maize lncRNAs from leaves and roots is responsive to combined salt and boron stress, being the first effort to identify lncRNAs from a maize landrace adapted to extreme conditions such as the Atacama Desert. The information generated is a starting point to understand the genomic adaptabilities suffered by this maize to surpass this extremely stressed

Deep Biosphere Secrets of the Mediterranean Salt Giant

NASA Astrophysics Data System (ADS)

Aloisi, Giovanni; Lugli, Stefano; McGenity, Terry; Kuroda, Junichiro; Takai, Ken; Treude, Tina; Camerlenghi, Angelo

2015-04-01

One component of the IODP multi-platform drilling proposal called DREAM (Deep-Sea Record of Mediterranean Messisnian Events), plans to investigate the deep biosphere associated to the Messinian Salinity Crisis (MSC) Salt Giant. We propose that the MSC Salt Giant, because of the variety of chemical environments it produces, has the potential to harbour an unprecedented diversity of microbial life with exceptional metabolic activity. Gypsum and anhydrite deposits provide a virtually unlimited source of sulphate at depths where oxidants are a rarity in other sedimentary environments. When reduced organic carbon comes into contact with these minerals there is the potential for a dynamic deep biosphere community of sulphate reducers to develop, with implications for sedimentary biogeochemical cycles and the souring of cruide oil. But the thickness of the Messinian evaporites and the range of chemical environments it harbours poses fundamental questions: will the interaction of several extreme conditions of temperature, salinity, pressure and chemical composition limit the ability of microbes to take advantage of such favourable thermodynamic conditions? And has such a diverse set of physical and chemical environments fostered microbal diversity, rather than phylogenetic specialization, as recent research into deep Mediterranean brine systems seems to indicate ? Over three kilometres in thickness, approaching the known temperature limits of life and with fluids precipitating carbonate, sulphate, halite and potash salts, microbes living within and around the MSC Salt Giant will be subject to the most exotic combinations of extremes, and have likely evolved yet unknown adaptations. Gypsum and Halite crystals contain fluid inclusions that are a micro-habitat in which microbes survive for tens of thousands, to possibly millions, of years, posing the fundamental question of cells devoting nearly all of their energy flow to somatic maintenance needs, rather than growth and

Reclaiming freshwater sustainability in the Cadillac Desert

PubMed Central

Sabo, John L.; Sinha, Tushar; Bowling, Laura C.; Schoups, Gerrit H. W.; Wallender, Wesley W.; Campana, Michael E.; Cherkauer, Keith A.; Fuller, Pam L.; Graf, William L.; Hopmans, Jan W.; Kominoski, John S.; Taylor, Carissa; Trimble, Stanley W.; Webb, Robert H.; Wohl, Ellen E.

2010-01-01

Increasing human appropriation of freshwater resources presents a tangible limit to the sustainability of cities, agriculture, and ecosystems in the western United States. Marc Reisner tackles this theme in his 1986 classic Cadillac Desert: The American West and Its Disappearing Water. Reisner's analysis paints a portrait of region-wide hydrologic dysfunction in the western United States, suggesting that the storage capacity of reservoirs will be impaired by sediment infilling, croplands will be rendered infertile by salt, and water scarcity will pit growing desert cities against agribusiness in the face of dwindling water resources. Here we evaluate these claims using the best available data and scientific tools. Our analysis provides strong scientific support for many of Reisner's claims, except the notion that reservoir storage is imminently threatened by sediment. More broadly, we estimate that the equivalent of nearly 76% of streamflow in the Cadillac Desert region is currently appropriated by humans, and this figure could rise to nearly 86% under a doubling of the region's population. Thus, Reisner's incisive journalism led him to the same conclusions as those rendered by copious data, modern scientific tools, and the application of a more genuine scientific method. We close with a prospectus for reclaiming freshwater sustainability in the Cadillac Desert, including a suite of recommendations for reducing region-wide human appropriation of streamflow to a target level of 60%. PMID:21149727

Reclaiming freshwater sustainability in the Cadillac Desert

USGS Publications Warehouse

Sabo, John L.; Sinha, Tushar; Bowling, Laura C.; Schoups, Gerrit H.W.; Wallender, Wesley W.; Campana, Michael E.; Cherkauer, Keith A.; Fuller, Pam L.; Graf, William L.; Hopmans, Jan W.; Kominoski, John S.; Taylor, Carissa; Trimble, Stanley W.; Webb, Robert H.; Wohl, Ellen E.

2010-01-01

Increasing human appropriation of freshwater resources presents a tangible limit to the sustainability of cities, agriculture, and ecosystems in the western United States. Marc Reisner tackles this theme in his 1986 classic Cadillac Desert: The American West and Its Disappearing Water. Reisner's analysis paints a portrait of region-wide hydrologic dysfunction in the western United States, suggesting that the storage capacity of reservoirs will be impaired by sediment infilling, croplands will be rendered infertile by salt, and water scarcity will pit growing desert cities against agribusiness in the face of dwindling water resources. Here we evaluate these claims using the best available data and scientific tools. Our analysis provides strong scientific support for many of Reisner's claims, except the notion that reservoir storage is imminently threatened by sediment. More broadly, we estimate that the equivalent of nearly 76% of streamflow in the Cadillac Desert region is currently appropriated by humans, and this figure could rise to nearly 86% under a doubling of the region's population. Thus, Reisner's incisive journalism led him to the same conclusions as those rendered by copious data, modern scientific tools, and the application of a more genuine scientific method. We close with a prospectus for reclaiming freshwater sustainability in the Cadillac Desert, including a suite of recommendations for reducing region-wide human appropriation of streamflow to a target level of 60%.

Theater of Operations Construction in the Desert: A Handbook of Lessons Learned in the Middle East

DTIC Science & Technology

1981-01-01

dehydrates the desert environment. In addition, the wind always carries fine soil particles which abrade building elements, clog mechar:ical devices, and...lower salt rejection, and increased likelihood of scaling and membrane hydrolysis . Manufacturers recommend that feed stream flows not be lower than...undergo accelerated decomposition /aging when stored in high desert heat. This is complicated by the fa~t that many of the tests were designed to be

Water deprivation affects serotoninergic system and glycoprotein secretion in the sub-commissural organ of a desert rodent Meriones shawi.

PubMed

Elgot, Abdeljalil; Ahboucha, Samir; Bouyatas, My Mustapha; Fèvre-Montange, Michèlle; Gamrani, Halima

2009-11-27

Water deprivation is a stress that has been associated with activation of several endocrine systems, including circumventricular organs of the central nervous system. The sub-comissural organ (SCO), characterized by its glycoprotein secretion called Reissner's fiber has been suggested to play a role in the regulation of body water balance. Meriones shawi, a semi-desertic rodent characterized by its resistance to long periods of thirst was subjected to water deprivation for 1 and 3 months. Effect of water deprivation was evaluated immunohistochemically on 5-hydroxytryptamine (5-HT; serotonin) system and glycoprotein secretion of the SCO. Our findings demonstrate significant reduction of anti-Reissner's fiber immunoreactive materials within basal and apical parts of the SCO ependymocytes. These changes seem to be the consequence of reduced control by 5-HT fibers reaching the SCO as a concomitant and significant reduction of anti-5-HT immunoreactive fibers are also observed following water deprivation. 5-HT immunoreactive reduction is seen in several regions in the brain including the neurons of origin within the dorsal raphe nucleus and the projecting supra and sub-ependymal fibers reaching the classical ependyma of the third ventricle. The extent of Reissner's fiber and 5-HT immunoreactive changes significantly correlates with the severity of water restriction. We suggest that water deprivation causes changes of the classical ependyma and the specialized ependyma that differentiates into the SCO as well as other cirumventricular organs such as the subfornical organ and the organum vasculosum laminae terminalis known to control drinking behaviors.

Cyanobacterial composition and spatial distribution based on pyrosequencing data in the Gurbantunggut Desert, Northwestern China.

PubMed

Zhang, Bingchang; Li, Renhui; Xiao, Peng; Su, Yangui; Zhang, Yuanming

2016-03-01

Cyanobacteria are the primary colonizers and form a dominant component of soil photosynthetic communities in biological soil crusts. They are crucial in improving soil environments, namely accumulating soil carbon and nitrogen. Many classical studies have examined cyanobacterial diversity in desert crusts, but relatively few comprehensive molecular surveys have been conducted. We used 454 pyrosequencing of 16S rRNA to investigate cyanobacterial composition and distribution on regional scales in the Gurbantunggut Desert. The relationship between cyanobacterial distribution and environmental factors was also explored. A total of 24,973 cyanobacteria partial 16S rRNA gene sequences were obtained, and 507OTUs were selected, as most OTUs had very few reads. Among these, 347 OTU sequences were of cyanobacteria origin, belonging to Oscillatoriales, Nostocales, Chroococcales, and uncultured cyanobacterium clone, respectively. Microcoleus vaginatus, Chroococcidiopsis spp. and M. steenstrupii were the dominant species in most areas of the Gurbantunggut Desert. Compared with other desert, the Gurbantunggut Desert differed in the prominence of Chroococcidiopsis spp. and lack of Pseudanabaenales. Species composition and abundance of cyanobacteria also showed distinct variations. Soil texture, precipitation, and nutrients and salt levels affected cyanobacterial distribution. Increased precipitation was helpful in improving cyanobacterial diversity. A higher content of coarse sand promoted the colonization and growth of Oscillatoriales and some phylotypes of Chroococcales. The fine-textured soil with higher nutrients and salts supported more varied populations of cyanobacteria, namely some heterocystous cyanobacteria. The results suggested that the Gurbantunggut Desert was rich in cyanobacteria and that precipitation was a primary regulating factor for cyanobacterial composition on a regional scale. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Salt management strategy defines the stem and leaf hydraulic characteristics of six mangrove tree species.

PubMed

Jiang, Guo-Feng; Goodale, Uromi Manage; Liu, Yan-Yan; Hao, Guang-You; Cao, Kun-Fang

2017-03-01

Mangroves in hypersaline coastal habitats are under constant high xylem tension and face great risk of hydraulic dysfunction. To investigate the relationships between functional traits and salt management, we measured 20 hydraulic and photosynthetic traits in four salt-adapted (SA) and two non-SA (NSA) mangrove tree species in south China. The SA species included two salt secretors (SSs), Avicennia marina (Forsskål) Vierhapper and Aegiceras corniculatum (L.) Blanco and two salt excluders (SEs), Bruguiera gymnorrhiza (L.) Savigny and Kandelia obovata (L.) Sheue et al. The two NSA species were Hibiscus tiliaceus (L.) and Pongamia pinnata (L.) Merr. Extremely high xylem cavitation resistance, indicated by water potential at 50% loss of xylem conductivity (Ψ50; -7.85 MPa), was found in SEs. Lower cavitation resistance was observed in SSs, and may result from incomplete salt removal that reduces the magnitude of xylem tension required to maintain water uptake from the soil. Surprisingly, the NSA species, P. pinnata, had very low Ψ50 (-5.44 MPa). Compared with NSAs, SAs had lower photosynthesis, vessel density, hydraulic conductivity and vessel diameter, but higher sapwood density. Eight traits were strongly associated with species' salt management strategies, with predawn water potential (ΨPD) and mean vessel diameter accounting for 95% flow (D95) having the most significant association; D95 separated SAs from NSAs and SEs had the lowest ΨPD. There was significant coupling between hydraulic traits and carbon assimilation traits. Instead of hydraulic safety being compromised by xylem efficiency, mangrove species with higher safety had higher efficiency and greater sapwood density (ρSapwood), but there was no relationship between ρSapwood and efficiency. Principal component analysis differentiated the species of the three salt management strategies by loading D, D95 and vessel density on the first axis and loading ΨPD, Ψ50 and water potential at 12% loss of xylem

Microbial Community Structure and the Persistence of Cyanobacterial Populations in Salt Crusts of the Hyperarid Atacama Desert from Genome-Resolved Metagenomics

DOE PAGES

Finstad, Kari M.; Probst, Alexander J.; Thomas, Brian C.; ...

2017-07-28

Although once thought to be devoid of biology, recent studies have identified salt deposits as oases for life in the hyperarid Atacama Desert. To examine spatial patterns of microbial species and key nutrient sources, we genomically characterized 26 salt crusts from three sites along a fog gradient. The communities are dominated by a large variety of Halobacteriales and Bacteroidetes, plus a few algal and Cyanobacterial species. CRISPR locus analysis suggests the distribution of a single Cyanobacterial population among all sites. This is in stark contrast to the extremely high sample specificity of most other community members. Only present at themore » highest moisture site is a genomically characterized Thermoplasmatales archaeon (Marine Group II) and six Nanohaloarchaea, one of which is represented by a complete genome. Parcubacteria (OD1) and Saccharibacteria (TM7), not previously reported from hypersaline environments, were found at low abundances. We found no indication of a N 2 fixation pathway in the communities, suggesting acquisition of bioavailable nitrogen from atmospherically derived nitrate. Samples cluster by site based on bacterial and archaeal abundance patterns and photosynthetic capacity decreases with increasing distance from the ocean. We conclude that moisture level, controlled by coastal fog intensity, is the strongest driver of community membership.« less

Microbial Community Structure and the Persistence of Cyanobacterial Populations in Salt Crusts of the Hyperarid Atacama Desert from Genome-Resolved Metagenomics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Finstad, Kari M.; Probst, Alexander J.; Thomas, Brian C.

Although once thought to be devoid of biology, recent studies have identified salt deposits as oases for life in the hyperarid Atacama Desert. To examine spatial patterns of microbial species and key nutrient sources, we genomically characterized 26 salt crusts from three sites along a fog gradient. The communities are dominated by a large variety of Halobacteriales and Bacteroidetes, plus a few algal and Cyanobacterial species. CRISPR locus analysis suggests the distribution of a single Cyanobacterial population among all sites. This is in stark contrast to the extremely high sample specificity of most other community members. Only present at themore » highest moisture site is a genomically characterized Thermoplasmatales archaeon (Marine Group II) and six Nanohaloarchaea, one of which is represented by a complete genome. Parcubacteria (OD1) and Saccharibacteria (TM7), not previously reported from hypersaline environments, were found at low abundances. We found no indication of a N 2 fixation pathway in the communities, suggesting acquisition of bioavailable nitrogen from atmospherically derived nitrate. Samples cluster by site based on bacterial and archaeal abundance patterns and photosynthetic capacity decreases with increasing distance from the ocean. We conclude that moisture level, controlled by coastal fog intensity, is the strongest driver of community membership.« less

Microbial Community Structure and the Persistence of Cyanobacterial Populations in Salt Crusts of the Hyperarid Atacama Desert from Genome-Resolved Metagenomics.

PubMed

Finstad, Kari M; Probst, Alexander J; Thomas, Brian C; Andersen, Gary L; Demergasso, Cecilia; Echeverría, Alex; Amundson, Ronald G; Banfield, Jillian F

2017-01-01

Although once thought to be devoid of biology, recent studies have identified salt deposits as oases for life in the hyperarid Atacama Desert. To examine spatial patterns of microbial species and key nutrient sources, we genomically characterized 26 salt crusts from three sites along a fog gradient. The communities are dominated by a large variety of Halobacteriales and Bacteroidetes, plus a few algal and Cyanobacterial species. CRISPR locus analysis suggests the distribution of a single Cyanobacterial population among all sites. This is in stark contrast to the extremely high sample specificity of most other community members. Only present at the highest moisture site is a genomically characterized Thermoplasmatales archaeon (Marine Group II) and six Nanohaloarchaea, one of which is represented by a complete genome. Parcubacteria (OD1) and Saccharibacteria (TM7), not previously reported from hypersaline environments, were found at low abundances. We found no indication of a N 2 fixation pathway in the communities, suggesting acquisition of bioavailable nitrogen from atmospherically derived nitrate. Samples cluster by site based on bacterial and archaeal abundance patterns and photosynthetic capacity decreases with increasing distance from the ocean. We conclude that moisture level, controlled by coastal fog intensity, is the strongest driver of community membership.

The impact of reduced gastric acid secretion on dissolution of salts of weak bases in the fasted upper gastrointestinal lumen: Data in biorelevant media and in human aspirates.

PubMed

Litou, Chara; Vertzoni, Maria; Xu, Wei; Kesisoglou, Filippos; Reppas, Christos

2017-06-01

To propose media for simulating the intragastric environment under reduced gastric acid secretion in the fasted state at three levels of simulation of the gastric environment and evaluate their usefulness in evaluating the intragastric dissolution of salts of weak bases. To evaluate the importance of bicarbonate buffer in biorelevant in vitro dissolution testing when using Level II biorelevant media simulating the environment in the fasted upper small intestine, regardless of gastric acid secretions. Media for simulating the hypochlorhydric and achlorhydric conditions in stomach were proposed using phosphates, maleates and bicarbonates buffers. The impact of bicarbonates in Level II biorelevant media simulating the environment in upper small intestine was evaluated so that pH and bulk buffer capacity were maintained. Dissolution data were collected using two model compounds, pioglitazone hydrochloride and semifumarate cocrystal of Compound B, and the mini-paddle dissolution apparatus in biorelevant media and in human aspirates. Simulated gastric fluids proposed in this study were in line with pH, buffer capacity, pepsin content, total bile salt/lecithin content and osmolality of the fasted stomach under partial and under complete inhibition of gastric acid secretion. Fluids simulating the conditions under partial inhibition of acid secretion were useful in simulating concentrations of both model compounds in gastric aspirates. Bicarbonates in Level III biorelevant gastric media and in Level II biorelevant media simulating the composition in the upper intestinal lumen did not improve simulation of concentrations in human aspirates. Level III biorelevant media for simulating the intragastric environment under hypochlorhydric conditions were proposed and their usefulness in the evaluation of concentrations of two model salts of weak bases in gastric aspirates was shown. Level II biorelevant media for simulating the environment in upper intestinal lumen led to

Mechanisms of range expansion and removal of mesquite in desert grasslands of the Southwestern United States

Treesearch

Thomas B. Wilson; Robert H. Webb; Thomas L. Thompson

2001-01-01

During the last 150 years, two species of mesquite trees in the Southwestern United States have become increasingly common in what formerly was desert grassland. These trees have spread from nearby watercourses onto relatively xeric upland areas, decreasing rangeland grass production. Management attempts to limit or reverse this spread have been largely unsuccessful....

A Pathogen Secreted Protein as a Detection Marker for Citrus Huanglongbing

PubMed Central

Pagliaccia, Deborah; Shi, Jinxia; Pang, Zhiqian; Hawara, Eva; Clark, Kelley; Thapa, Shree P.; De Francesco, Agustina D.; Liu, Jianfeng; Tran, Thien-Toan; Bodaghi, Sohrab; Folimonova, Svetlana Y.; Ancona, Veronica; Mulchandani, Ashok; Coaker, Gitta; Wang, Nian; Vidalakis, Georgios; Ma, Wenbo

2017-01-01

The citrus industry is facing an unprecedented crisis due to Huanglongbing (HLB, aka citrus greening disease), a bacterial disease associated with the pathogen Candidatus Liberibacter asiaticus (CLas) that affects all commercial varieties. Transmitted by the Asian citrus psyllid (ACP), CLas colonizes citrus phloem, leading to reduced yield and fruit quality, and eventually tree decline and death. Since adequate curative measures are not available, a key step in HLB management is to restrict the spread of the disease by identifying infected trees and removing them in a timely manner. However, uneven distribution of CLas cells in infected trees and the long latency for disease symptom development makes sampling of trees for CLas detection challenging. Here, we report that a CLas secreted protein can be used as a biomarker for detecting HLB infected citrus. Proteins secreted from CLas cells can presumably move along the phloem, beyond the site of ACP inoculation and CLas colonized plant cells, thereby increasing the chance of detecting infected trees. We generated a polyclonal antibody that effectively binds to the secreted protein and developed serological assays that can successfully detect CLas infection. This work demonstrates that antibody-based diagnosis using a CLas secreted protein as the detection marker for infected trees offers a high-throughput and economic approach that complements the approved quantitative polymerase chain reaction-based methods to enhance HLB management programs. PMID:29403441

Tree production in desert regions using effluent and water harvesting

Treesearch

Martin M. Karpiscak; Gerald J. Gottfried

2000-01-01

Treated municipal effluent combined with water harvesting can be used for land restoration and enhancing the growth of important riparian tree species. Paired studies in Arizona are assessing the potential of growing trees using mixtures of effluent and potable water. Trees are grown in the field and in containers. Initial results from the field show high survival for...

Information Theoretic Secret Key Generation: Structured Codes and Tree Packing

ERIC Educational Resources Information Center

Nitinawarat, Sirin

2010-01-01

This dissertation deals with a multiterminal source model for secret key generation by multiple network terminals with prior and privileged access to a set of correlated signals complemented by public discussion among themselves. Emphasis is placed on a characterization of secret key capacity, i.e., the largest rate of an achievable secret key,…

Transition from arid to hyper-arid environment in the southern Levant deserts as recorded by early Pleistocene cummulic Aridisols

NASA Astrophysics Data System (ADS)

Amit, Rivka; Simhai, Ori; Ayalon, Avner; Enzel, Yehouda; Matmon, Ari; Crouvi, Onn; Porat, Naomi; McDonald, Eric

2011-02-01

The time at which deserts established their current arid or hyper-arid conditions remains a fundamental question regarding the history of Earth. Cosmogenic isotope exposure ages of desert pavement and welded, calcic-gypsic-salic Reg soils that developed on relatively flat alluvial surfaces ˜2 Ma ago in the Negev Desert indicate long geomorphic stability under extremely dry conditions. Over a short interval during their initial stage of development between 1-2 Ma, these cumulative soils are characterized by calcic soils reaching maximum stage III of carbonate morphology. This interval is the only period when calcic soil horizons formed on stable abandoned alluvial surfaces in the southern Negev Desert. Since ˜1 Ma pedogenesis changed toward more arid soil environment and the formation of gypsic-salic soil horizons that were later followed by dust accumulation. The dichotomy of only moderately-developed calcic soil (stages II-III) during a relatively long time interval (10 5-10 6 years) indicates an arid environment that does not support continuous development but only occasional calcic soil formation. The very low δ18O and relatively high δ13C values of these early pedogenic carbonates support soil formation under arid climatic conditions. Such an environment was probably characterized by rare and relatively longer duration rainstorms which occasionally allowed deeper infiltration of rainwater and longer retention of soil moisture. This, in turn enabled the growth of sparse vegetation that enhanced deposition of pedogenic carbonate. At ˜1 Ma these rare events of slightly wetter conditions ceased and less atmospheric moisture reached the southern Negev Desert leading to deposition of soluble salts and dust deposited in the soils. The combination of long-term hyperaridity, scarcity of vegetation and lack of bioturbation, salts cementation, dust accumulation and tight desert pavement cover, has protected the surfaces from erosion forming one of the most remarkably

Making Plants Break a Sweat: the Structure, Function, and Evolution of Plant Salt Glands

PubMed Central

Dassanayake, Maheshi; Larkin, John C.

2017-01-01

Salt stress is a complex trait that poses a grand challenge in developing new crops better adapted to saline environments. Some plants, called recretohalophytes, that have naturally evolved to secrete excess salts through salt glands, offer an underexplored genetic resource for examining how plant development, anatomy, and physiology integrate to prevent excess salt from building up to toxic levels in plant tissue. In this review we examine the structure and evolution of salt glands, salt gland-specific gene expression, and the possibility that all salt glands have originated via evolutionary modifications of trichomes. Salt secretion via salt glands is found in more than 50 species in 14 angiosperm families distributed in caryophyllales, asterids, rosids, and grasses. The salt glands of these distantly related clades can be grouped into four structural classes. Although salt glands appear to have originated independently at least 12 times, they share convergently evolved features that facilitate salt compartmentalization and excretion. We review the structural diversity and evolution of salt glands, major transporters and proteins associated with salt transport and secretion in halophytes, salt gland relevant gene expression regulation, and the prospect for using new genomic and transcriptomic tools in combination with information from model organisms to better understand how salt glands contribute to salt tolerance. Finally, we consider the prospects for using this knowledge to engineer salt glands to increase salt tolerance in model species, and ultimately in crops. PMID:28400779

Seed dispersal and seed fate in Joshua tree (Yucca brevifolia)

USGS Publications Warehouse

Waitman, B.A.; Vander Wall, S.B.; Esque, Todd

2012-01-01

Joshua tree (Yucca brevifolia) is a charismatic symbol of the Mojave Desert. Despite its familiarity, we know little about the reproduction of this species, including mechanisms of seed dispersal. Here we examine mechanisms of seed dispersal and resulting seed fate. We experimentally tracked fruit and seed removal and followed the fates of Joshua tree seeds using radioactive tracers. The majority of Joshua tree fruits monitored were taken directly from the tree canopy by white-tailed antelope squirrels, and seeds and fruits on the soil surface were quickly removed by animals. Rodents given seeds labeled with scandium-46 cached them between 0.1 cm and 4.1 cm deep. Seedling emergence was most common for seeds planted 1 cm deep, whereas seeds placed on the soil surface seldom germinated. Wind dispersal is unlikely because fruits and seeds lack adaptations for wind dispersal; wind speeds required to move Joshua tree seeds and fruits across the soil surface were higher than those typically found in the Mojave Desert. Further, rodents removed most seeds before abiotic burial was possible. We conclude that most Joshua tree seeds are dispersed by scatter hoarding by rodents, and that caches made by rodents are suitable sites for seedling emergence.

The salinity tolerant poplar database (STPD): a comprehensive database for studying tree salt-tolerant adaption and poplar genomics.

PubMed

Ma, Yazhen; Xu, Ting; Wan, Dongshi; Ma, Tao; Shi, Sheng; Liu, Jianquan; Hu, Quanjun

2015-03-17

Soil salinity is a significant factor that impairs plant growth and agricultural productivity, and numerous efforts are underway to enhance salt tolerance of economically important plants. Populus species are widely cultivated for diverse uses. Especially, they grow in different habitats, from salty soil to mesophytic environment, and are therefore used as a model genus for elucidating physiological and molecular mechanisms of stress tolerance in woody plants. The Salinity Tolerant Poplar Database (STPD) is an integrative database for salt-tolerant poplar genome biology. Currently the STPD contains Populus euphratica genome and its related genetic resources. P. euphratica, with a preference of the salty habitats, has become a valuable genetic resource for the exploitation of tolerance characteristics in trees. This database contains curated data including genomic sequence, genes and gene functional information, non-coding RNA sequences, transposable elements, simple sequence repeats and single nucleotide polymorphisms information of P. euphratica, gene expression data between P. euphratica and Populus tomentosa, and whole-genome alignments between Populus trichocarpa, P. euphratica and Salix suchowensis. The STPD provides useful searching and data mining tools, including GBrowse genome browser, BLAST servers and genome alignments viewer, which can be used to browse genome regions, identify similar sequences and visualize genome alignments. Datasets within the STPD can also be downloaded to perform local searches. A new Salinity Tolerant Poplar Database has been developed to assist studies of salt tolerance in trees and poplar genomics. The database will be continuously updated to incorporate new genome-wide data of related poplar species. This database will serve as an infrastructure for researches on the molecular function of genes, comparative genomics, and evolution in closely related species as well as promote advances in molecular breeding within Populus. The

Potash brines in the Great Salt Lake Desert, Utah: Chapter B in Contributions to economic geology (short papers and preliminary reports), 1927: Part I - Metals and nonmetals except fuels

USGS Publications Warehouse

Nolan, T.B.

1927-01-01

During and immediately after the war the brines of the Salduro Marsh, in the Great Salt Lake Desert, were a source of considerable potash for the domestic supply. Although no potash has been produced from these brines in the last few years, a continued interest in the area has been shown by a large number of filings, in different parts of the desert, under the potash law of October 2, 1917 (40 Stat. 297), and the regulations issued under that law by the Department of the Interior on March 21, 1918, in Circular 594 (46 L. D. 323).As the basis for appropriate action on these permit, lease, and patent filings the Department of the Interior required information concerning the mode of occurrence, distribution, and general characteristics of the potassium-bearing brines in this region. Field investigation was accordingly undertaken for the primary purpose of satisfying these requirements.The work was done by the Geological Survey and the General Land Office in cooperation with the Bureau of Mines. The Bureau of Mines furnished an autotruck and a mechanic, who also assisted in the field work, and, for a period of a month, a mine rescue car, which permitted the establishment of headquarters in parts of the desert far from sources of supplies and water. The General Land Office surveyed the boundaries of townships over the desert and located the drill holes from which samples of brine were taken.The writer directed the work for the Geological Survey, and the analyses of the samples of brine were made in the Survey's chemical laboratory. The greater part of the field work was done between April 17 and July 7, 1925, and the work was finished during the two periods August 17-26 and September 30 to October 2. Adverse weather throughout the season hindered the work.

Desert Southwest Community Tree Guide: Benefits, Costs and Strategic Planting

Treesearch

Greg McPherson; J.R. Simpson; P.J. Peper; S.E. Maco; Q. Xiao; E. Mulrean

2004-01-01

This report quantifies benefits and costs for typical large-, medium-, small-stature, deciduous trees (Fraxinus uhdei, Prosopis chilensis, Acacia farnesiana), as well as a conifer (Pinus halapensis). The analysis assumed that trees were planted in a residential yard site or a public (street/park) site, a 40-year time frame, and...

How much Carbon is Stored in Deserts? AN Approach for the Chilean Atacama Desert Using LANDSAT-8 Products

NASA Astrophysics Data System (ADS)

Hernández, H. J.; Acuña, T.; Reyes, P.; Torres, M.; Figueroa, E.

2016-06-01

The Atacama Desert in northern Chile is known as the driest place on Earth, with an average rainfall of about 15 mm per year. Despite these conditions, it contains a rich variety of flora with hundreds of species characterised by their extraordinary ability to adapt to this extreme environment. These biotic components have a direct link to important ecosystem services, especially those related to carbon storage and sequestration. No quantitative assessment is currently available for these services and the role of the desert in this matter remains unclear. We propose an approach to estimate above-ground biomass (AGB) using Landsat-8 data, which we tested in the Taparacá region, located in the northern section of the desert. To calibrate and validate the models, we used field data from 86 plots and several spectral indexes (NDVI, EVI and SAVI) obtained from the provisional Landsat-8 Surface-reflectance products. We applied randomised branch sampling and allometry principles (non-destructive methods) to collect biomass samples for all plant biological types: wetlands, steppes, shrubs and trees. All samples were dried in an oven until they reached constant weight and the final values were used to extrapolate dry matter content (AGB) to each plot in terms of kg m-2. We used all available scenes from September 2014 to August 2015 to calculate the maximum, minimum and average value for each index in each pixel within this period. For modeling, we used the method based on classification and regression trees called random forest (RF), available in the statistical software R-Project. The explained variance obtained by the RF algorithm was around 80-85%, and it improved when a wetland vector layer was used as the predictive factor in the model to reach the range 85-90%. The mean error was 1.45 kg m-2 of dry matter. The best model was obtained using the maximum and mean values of SAVI and EVI indexes. We were able to estimate total biomass storage of around 8 million tons

A study of Desert Dermatoses in the Thar Desert Region.

PubMed

Chatterjee, Manas; Vasudevan, Biju

2015-01-01

Desert dermatology describes the cutaneous changes and the diseases affecting those living in the desert. Diurnal variation in temperature is high and is characteristic of the deserts. The lack of water affects daily activities and impacts dermatological conditions. Adaptation to the desert is therefore important to survival. This original article focuses on dermatoses occurring in a population in the Thar desert of India, predominantly located in Rajasthan. This is a descriptive study involving various dermatoses seen in patients residing in the Thar desert region over a duration of 3 years. Infections were the most common condition seen among this population and among them fungal infections were the most common. The high incidence of these infections would be accounted for by the poor hygienic conditions due to lack of bathing facilities due to scarcity of water and the consequent sweat retention and overgrowth of cutaneous infective organisms. Pigmentary disorders, photodermatoses, leishmaniasis and skin tumors were found to be more prevalent in this region. Desert sweat dermatitis was another specific condition found to have an increased incidence. The environment of the desert provides for a wide variety of dermatoses that can result in these regions with few of these dermatoses found in much higher incidence than in other regions. The concept of desert dermatology needs to be understood in more details to provide better care to those suffering from desert dermatoses and this article is a step forward in this regard.

Characteristics and functions of semi-desert soils in the Negev (Israel) depending on precipitation, relief and vegetation

NASA Astrophysics Data System (ADS)

Felde, V.; Drahorad, S.; Felix-Henningsen, P.

2009-04-01

The Negev desert in south western Israel has been the subject of several investigations concerning soil forming processes and matter fluxes in desert soils. In order to investigate the influence of the ‘global change' on semi-desert ecosystems, study sites along a steep rainfall gradient are of great advantage. The study site "Nizzana 69", which is in the focus of this study, lies about 25 km south of the Mediterranean Sea near the border between Israel and Egypt. The area has an annual rainfall of approximately 170 mm * a-1. A catena consisting of six profiles, three under the legume Retama raetam and three in the bare interspace between shrubs was investigated in order to show the impact of this perennial plant and the relief on soil properties. The results show a strong influence of the shrub due to accumulation of nutrients, carbonates and soluble salts, which were precipitated with dust and rainfall, or which derive from mineralisation of plant litter. The interspace between the plants is covered by a biological soil crust, which also strongly influences the matter fluxes by creating runoff, nitrogen-fixation and stabilizing the soil surface and protecting it against deflation. The distribution of salts and carbonates in the profiles indicate leaching processes. All soils of the study site "Nizzana 69" are weekly developed Arenosols without horizons of carbonate or salt enrichment to a depth of 1 m. The comparison with other areas along the rainfall gradient shows higher inputs of soluble salts with increasing precipitation due to wet deposition, while carbonate contents increase with decreasing precipitation due to deposition of dust, which was generated in the lime stone Negev. On the other hand leaching of soluble soil constituents decreases and accumulation in the upper soil horizon increases with decreasing annual precipitation. Furthermore the importance of local relief aspects for plant growth decreases with increasing rainfall.

Cyanotoxins in desert environments may present a risk to human health.

PubMed

Metcalf, J S; Richer, R; Cox, P A; Codd, G A

2012-04-01

There have been few studies concerning cyanotoxins in desert environments, compared with the multitude of studies of cyanotoxins in aquatic environments. However, cyanobacteria are important primary producers in desert environments, where after seasonal rains they can grow rapidly both stabilising and fertilising arid habitats. Samples of cyanobacteria from wadis - dry, ephemeral river beds - and sabkha - supertidal salt flats - in Qatar were analysed for the presence of microcystins, nodularin, anatoxin-a, cylindrospermopsin and anatoxin-a(S). Microcystins were detected by HPLC-PDA and ELISA at concentrations between 1.5 and 53.7ngg(-1) dry wt of crust. PCR products for the mycD gene for microcystin biosynthesis were detected after amplification of DNA from desert crust samples at two out of three sample sites. The presence of anatoxin-a(S) was also indicated by acetylcholine esterase inhibition assay. As a function of area of desert crust, microcystin concentrations were between 3 and 56μgm(-2). Based on the concentration of microcystins detected in crust, with reference to the published inhalation NOAEL and LOAEL values via nasal spray inhalation of purified microcystin-LR in aqueous solution, and the amount of dust potentially inhaled by a person from these dried crusts, the dose of microcystins could exceed a calculated TDI value of 1-2ngkg(-1)day(-1) for an average adult. The presence of microcystins, and potentially of anatoxin-a(S), in desert crusts has important implications for human health. Further studies are required to monitor desert dust storms for the presence of cyanotoxins. An understanding of the risks of inhaling particles containing cyanotoxins is also warranted. Copyright © 2012 Elsevier B.V. All rights reserved.

Wood decay in desert riverine environments

USGS Publications Warehouse

Andersen, Douglas; Stricker, Craig A.; Nelson, S. Mark

2016-01-01

Floodplain forests and the woody debris they produce are major components of riverine ecosystems in many arid and semiarid regions (drylands). We monitored breakdown and nitrogen dynamics in wood and bark from a native riparian tree, Fremont cottonwood (Populus deltoides subsp. wislizeni), along four North American desert streams. We placed locally-obtained, fresh, coarse material [disks or cylinders (∼500–2000 cm3)] along two cold-desert and two warm-desert rivers in the Colorado River Basin. Material was placed in both floodplain and aquatic environments, and left in situ for up to 12 years. We tested the hypothesis that breakdown would be fastest in relatively warm and moist aerobic environments by comparing the time required for 50% loss of initial ash-free dry matter (T50) calculated using exponential decay models incorporating a lag term. In cold-desert sites (Green and Yampa rivers, Colorado), disks of wood with bark attached exposed for up to 12 years in locations rarely inundated lost mass at a slower rate (T50 = 34 yr) than in locations inundated during most spring floods (T50 = 12 yr). At the latter locations, bark alone loss mass at a rate initially similar to whole disks (T50 = 13 yr), but which subsequently slowed. In warm-desert sites monitored for 3 years, cylinders of wood with bark removed lost mass very slowly (T50 = 60 yr) at a location never inundated (Bill Williams River, Arizona), whereas decay rate varied among aquatic locations (T50 = 20 yr in Bill Williams River; T50 = 3 yr in Las Vegas Wash, an effluent-dominated stream warmed by treated wastewater inflows). Invertebrates had a minor role in wood breakdown except at in-stream locations in Las Vegas Wash. The presence and form of change in nitrogen content during exposure varied among riverine environments. Our results suggest woody debris breakdown in desert riverine ecosystems is primarily a microbial process with rates determined by landscape position

The Presence and Distribution of Salts as a Palaeoprecipitation Proxy in Atacama Soils

NASA Astrophysics Data System (ADS)

McKay, Lucy; Claire, Mark

2016-04-01

The Atacama Desert in northern Chile (17 to 27° S) is the driest and oldest warm desert on Earth and contains unique abundances of atmospherically-derived salts such as nitrate and perchlorate (Ewing et al., 2006; Jackson et al., 2015). Near-surface accumulation of extremely soluble salts indicates a scarcity of long-term precipitation-driven leaching from Atacama soils. The prolonged absence of substantial precipitation has enabled nitrate and perchlorate to accumulate for millions of years to measurable levels, while interacting with occasional rainfall to move vertically through the soil profile. We investigate the near-surface presence and distribution of atmospherically-generated soluble salts at Earth's most arid extreme, aiming to quantify Atacama palaeoprecipitation during the Quaternary. Previous field and modelling studies have revealed a strong correlation between the depth of peak nitrate and past precipitation events in the U.S. desert southwest (Walvoord et al., 2003; Marion et al., 2008). We extend these studies to regions of much lower rainfall, and report the largest ever near-surface concentrations of nitrate and perchlorate in Earth's soils. We present salt distribution profiles from soil pits in six localities, spanning ~1000 km of the south-to-north (27° to 24° S) natural rainfall and ecosystem function gradient that spans the arid to hyperarid transition (from 20 to <1 mm rainfall y-1). Localities include the well-characterised Yungay desert research station, initially declared as the driest place on Earth beyond the limit for microbial life (McKay et al., 2003). Importantly, our nitrate and perchlorate data confirm and extend suspicions that drier localities than Yungay exist (Azua-Bustos et al., 2015). For example, our "km40" site reveals 10 mg/kg of perchlorate at the surface, with a peak of 35 mg/kg at 10 cm depth. At "PONR", perchlorate peaks at >100 mg/kg at 120 cm depth, with an astonishing 22 mg/kg at the surface. In comparison

Salt-driven interactions between Pistacia lentiscus and Salsola inermis.

PubMed

Barazani, Oz; Golan-Goldhirsh, Avi

2009-11-01

It can be learned from the Pistacia spp. germplasm collection (http://www.bgu.ac.il/pistacia) that the growth of Salsola inermis is inhibited in the vicinity of the evergreen Pistacia lentiscus, but not in the surroundings of the deciduous Pistacia atlantica and Pistacia chinensis. Irrigation of trees during the summer months increases soil salinity around the trees. It was therefore hypothesized that inhibition of S. inermis around P. lentiscus is related to depletion of salt in the vicinity of the latter species. A multi-approach experimental scheme was carried out which included soil edaphic characterization and germination tests. To test salt tolerance of P. lentiscus, plants were grown in a hydroponic system for a month in medium containing NaCl, while physiological and growth parameters were measured. Conductivity measurements in summer, during the growth season of S. inermis, indicated that soil salinity beneath deciduous Pistacia trees was significantly higher than that below P. lentiscus. Germination of S. inermis seeds on filter paper moistened with P. lentiscus low-conductivity soil filtrate was twice as high as that of the deciduous trees high-conductivity soil filtrates. Nevertheless, fresh and dry weights of mature S. inermis growing next to P. atlantica and P. chinensis were 2.9 to 4.8 times higher than those of plants growing in the vicinity of P. lentiscus. In a hydroponic system, no significant differences were found in growth parameters and stomatal conductance between P. lentiscus growing in control and salt treatments. It was therefore proposed that salt depletion in the vicinity of P. lentiscus inhibits the growth, but not germination, of S. inermis thus confirming the halophylic characteristics of this plant. The nature of Salsola-Pistacia interactions cannot be explained by allelopathic effects; hence, plausible salt-driven interactions were considered. Our data showed that S. inermis accumulated salt and has halophytic characteristics

Bioinformatics approach of salt tolerance gene in mangrove plant Rhizophora stylosa

NASA Astrophysics Data System (ADS)

Basyuni, M.; Sumardi

2017-01-01

This study descibes bioinformatics approach on the analyze of the salt tolerance genes in mangrove plant, Rhizophora stylosa on DDBJ/EMBL/GenBank as well as similarity, phylogenetic, potential peptide, and subcellular localization. The DNA sequence between salt tolerance gene from R. stylosa exhibited 42-11% between themselves The target peptide value of mitochondria varied from 0.163 to 0.430, indicated it was possible to exist. These results suggested the importance of understanding the diversity and functional of properties of the different amino acids in mangrove OSC genes. To clarify the relationship among the salt-tolerant genes in R. stylosa, a phylogenetic tree was constructed. The phylogenetic tree shows that there are three clusters, first branch of Cu/Zn SOD and reverse transcriptase genes, the second branch consists of the majority genes and the last group was MAP3K alpha protein kinase only. The present study, therefore, suggested that salt tolerance genes form distinct clusters in the tree.

Are There High Meteorite Concentrations in the Atacama Desert/Chile?

NASA Astrophysics Data System (ADS)

Scherer, P.; Delisle, G.

1992-07-01

We have visited numerous regions of the Atacama desert between Copiapo (27 degrees, 15'S) and Calama (22 degrees, 25'S) to assess their potential as a high-yield meteorite concentration surface, easily exploitable by search efforts within a reasonable time frame. According to our observations, this desert is characterized by the following features: a) A high percentage of the desert consists of sloping surfaces on which soil movement occurs, presumably by very infrequent, though heavy rain. b) Vast areas of the desert are covered by a dm-thick sand layer of dark colour. Since the sand is too coarse-grained to be transported by wind it presumably resulted from in-situ weathering of rock debris derived from nearby mountains. We suspect that impacting smaller objects can easily penetrate the sand layer. c) The sand layer is typically dotted by rocks, fist-size or smaller, that are covered by a thick layer of desert paint (reddish-brown to black colour). Most country rocks are of volcanic origin (rhyolite, andesite, basalt) and are typically of grey to black colour. A noticeable colour contrast in particular to potential stony meteorites is almost nonexistent. d) Soil salts with a potential to speed up weathering processes are ubiquitous near the surface. e) The Pampa de Mejillones, 45 km north of Antofagasta, is one of the few light-coloured areas in the Atacama desert. The surface, being of Mio-Pliocene age, consists of an almost continuous layer of light-brown fossil shells (bivalves and gastropodes). Fluvially transported dark rocks from adjacent outcrops rest on top. The latter material is covered again by desert paint. Few meteorite discoveries have been reported from this area (Pampa (a),(b),(c)). f) Numerous old tire tracks, in particular around mines in operation, crisscross most areas of the Atacama. Undetected objects such as large masses of iron bodies are not likely to have remained undiscovered in great numbers any more. We conclude that the potential of

Aldosterone hypersecretion in “non-salt-losing” congenital adrenal hyperplasia

PubMed Central

Bartter, Frederic C.; Henkin, Robert I.; Bryan, George T.

1968-01-01

Patients with the “non-salt-losing” form of the adrenogenital syndrome were studied before and after suppression of adrenal cortical activity with carbohydrate-active steroids. The response of aldosterone secretion to sodium deprivation was measured; in some patients response to adrenocorticotropic hormone (ACTH) was measured as well. The aldosterone secretion was normal and responded normally to sodium deprivation in all patients studied during suppression with carbohydrate-active steroids. This finding suggests that 21-hydroxylation of progesterone is normal in this syndrome. The sole abnormality in the production of aldosterone in these patients was found to be excessive secretion of aldosterone while they were not receiving suppressive doses of carbohydrate-active steroids. This finding strongly supports the view that the biogenetic pathways through which aldosterone is produced from progesterone are intact in this syndrome. No patient showed hypertension or hypokalemic alkalosis despite very high aldosterone secretion rates. This observation suggests that the hyper-aldosteronism is secondary to a tendency to sodium loss in the patient whose ACTH production is not suppressed. These studies provide additional evidence in support of the hypothesis that the salt-losing and “non-salt-losing” forms of adrenogenital syndrome are genetically and biochemically distinct. PMID:4299011

Cystic fibrosis respiratory tract salt concentration: An Exploratory Cohort Study.

PubMed

Grandjean Lapierre, Simon; Phelippeau, Michael; Hakimi, Cyrine; Didier, Quentin; Reynaud-Gaubert, Martine; Dubus, Jean-Christophe; Drancourt, Michel

2017-11-01

In cystic fibrosis patients, electrolytic and osmolality imbalance secondary to cystic fibrosis transmembrane conductance regulator mutations may impact on mucoid secretion accumulation and secondary colonization by opportunistic pathogens such as nontuberculous mycobacteria.We performed a noninvasive exploratory prospective controlled clinical study comparing sputum salinity and acid-base characteristics of cystic fibrosis and noncystic fibrosis control patients. A total of 57 patients and 62 controls were included.Sputum salt concentrations were 10.5 g/L (95% CI: 7.7-13.3) in patients and 7.4 g/L (95% CI: 5.9-8.9) in aged-matched controls, a difference that was found to be statistically significant (P < .05). No difference in pH was observed between patients and controls.These differences in respiratory secretions salt concentrations could influence host-pathogen interactions in the context of cystic fibrosis respiratory infections. We propose to include respiratory secretion salt measurement as a routine analysis on cystic fibrosis patients' sputum submitted for bacterial culture. Copyright © 2017 The Authors. Published by Wolters Kluwer Health, Inc. All rights reserved.

The genetic architecture of shoot-root covariation during seedling emergence of a desert tree, Populus euphratica.

PubMed

Zhang, Miaomiao; Bo, Wenhao; Xu, Fang; Li, Huan; Ye, Meixia; Jiang, Libo; Shi, Chaozhong; Fu, Yaru; Zhao, Guomiao; Huang, Yuejiao; Gosik, Kirk; Liang, Dan; Wu, Rongling

2017-06-01

The coordination of shoots and roots is critical for plants to adapt to changing environments by fine-tuning energy production in leaves and the availability of water and nutrients from roots. To understand the genetic architecture of how these two organs covary during developmental ontogeny, we conducted a mapping experiment using Euphrates poplar (Populus euphratica), a so-called hero tree able to grow in the desert. We geminated intraspecific F 1 seeds of Euphrates Poplar individually in a tube to obtain a total of 370 seedlings, whose shoot and taproot lengths were measured repeatedly during the early stage of growth. By fitting a growth equation, we estimated asymptotic growth, relative growth rate, the timing of inflection point and duration of linear growth for both shoot and taproot growth. Treating these heterochronic parameters as phenotypes, a univariate mapping model detected 19 heterochronic quantitative trait loci (hQTLs), of which 15 mediate the forms of shoot growth and four mediate taproot growth. A bivariate mapping model identified 11 pleiotropic hQTLs that determine the covariation of shoot and taproot growth. Most QTLs detected reside within the region of candidate genes with various functions, thus confirming their roles in the biochemical processes underlying plant growth. © 2017 The Authors The Plant Journal © 2017 John Wiley & Sons Ltd.

Secrets of the Soil: Promotion of the Nov. 7 Science at the Theater Event

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brodie, Eoin

2011-01-01

There are billions of microbes in a handful of soil, some of which could hold the key to our climate and energy future. Find out how at Secrets of the Soil, our next Science at the Theater Nov. 7 at the Berkeley Repertory Theatre. At the event, four Berkeley Lab scientists will reveal how our scientists travel the globe -- to deserts, rainforests, and the Arctic tundra -- to explore the secret world of soil microbes -- and what they mean to you. More info: http://www.lbl.gov/LBL-PID/fobl/

Secrets of the Soil: Promotion of the Nov. 7 Science at the Theater Event

ScienceCinema

Brodie, Eoin

2017-12-11

There are billions of microbes in a handful of soil, some of which could hold the key to our climate and energy future. Find out how at Secrets of the Soil, our next Science at the Theater Nov. 7 at the Berkeley Repertory Theatre. At the event, four Berkeley Lab scientists will reveal how our scientists travel the globe -- to deserts, rainforests, and the Arctic tundra -- to explore the secret world of soil microbes -- and what they mean to you. More info: http://www.lbl.gov/LBL-PID/fobl/

[Spatial heterogeneity of soil salinization and its influencing factors in the typical region of the Mu Us Desert-Loess Plateau transitional zone, Northwest China].

PubMed

Zhao, Xuan; Hao, Qi Li; Sun, Ying Ying

2017-06-18

Studies on the spatial heterogeneity of saline soil in the Mu Us Desert-Loess Plateau transition zone are meaningful for understanding the mechanisms of land desertification. Taking the Mu Us Desert-Loess Plateau transition zone as the study subject, its spatial heterogeneity of pH, electrical conductivity (EC) and total salt content were analyzed by using on-site sampling followed with indoor analysis, classical statistical and geostatistical analysis. The results indicated that: 1) The average values of pH, EC and total salt content were 8.44, 5.13 mS·cm -1 and 21.66 g·kg -1 , respectively, and the coefficient of variation ranged from 6.9% to 73.3%. The pH was weakly variable, while EC and total salt content were moderately variable. 2) Results of semivariogram analysis showed that the most fitting model for spatial variability of all three indexes was spherical model. The C 0 /(C 0 +C) ratios of three indexes ranged from 8.6% to 14.3%, which suggested the spatial variability of all indexes had a strong spatial autocorrelation, and the structural factors played a more important role. The variation range decreased in order of pH salt < EC. The Kriging interpolation showed that pH, EC and total salt content distributed in a striped pattern with good continuity. The pH value increased with increasing terrain slope, while EC and total salt content decreased. 3) In terms of vertical distribution, the salt aggregated on surface in the area with severe salinization. In the area with light salinization, the vertical distribution of salinity was firstly decreased and then increased. In general, the heterogeneity of soil salinization in the Mu Us Desert-Loess Plateau transition zone was influenced by climate, landscape, plant distribution, especially affected by geological conditions, topography and hydrogeological conditions. This study provided a theoretical basis for future land engineering and ecosystem restoration programs.

The Groot Effect: Plant facilitation and desert shrub regrowth following extensive damage.

PubMed

Lortie, Christopher J; Gruber, Eva; Filazzola, Alex; Noble, Taylor; Westphal, Michael

2018-01-01

Deserts are increasing in extent globally, but existing deserts are decreasing in health. The basic biology and ecology of foundation plant species in deserts are limited. This is a direct study that provides an estimate of the capacity for a locally dominant foundation shrub species in California to recover from damage. Desert shrubs are cleared and damaged by humans for many purposes including agriculture, oil and gas production, and sustainable energy developments; we need to know whether foundation species consistently facilitate the abundance and diversity of other plants in high-stress ecosystems and whether they can recover. A total of 20 Ephedra californica shrubs were clipped to the ground at a single site and systematically resampled for regrowth 2 years later. These shrubs were damaged once and regrew rapidly, and relatively, larger shrubs were not more resilient. This study provides evidence for what we termed the "Groot Effect" because smaller individuals of this shrub species can recover from significant aboveground damage and continue to have positive effects on other plant species (similar to the popular culture reference to a benefactor tree species). The density of other plant species was consistently facilitated while effects on diversity varied with season. These findings confirm that E. californica is a foundation species that can be an important restoration tool within the deserts of California in spite of extreme cycles of drought and physical damage to its canopy.

Neural modulation of salt secretion in teleostopercular epithelium by 2-adrenergic receptors and inositol 1,4,5-trisphosphate

PubMed

Marshall; Duquesnay; Gillis; Bryson; Liedtke

1998-05-21

Opercular epithelia from seawater-adapted killifish (Fundulus heteroclitus) were dissected with the nerve intact, mounted in Ussing-style membrane chambers and bathed in symmetrical saline solutions. Nerve stimulation rapidly inhibited transepithelial current (a measure of Cl- secretion rate) by 27.3+/-3.3 % (N=22), and the effect could be sustained for more than 10 min using intermittent pulse trains at 10 Hz. The effect was blocked in a dose-dependent manner by yohimbine, but not by propranolol, atropine or tubocurarine, indicating mediation by 2-adrenergic receptors. The effect was also present, but significantly diminished, in opercular membranes from animals that had been transferred to sea water for 48 h (18+/-8.6 % inhibition, N=14). The resting current and the effect were absent in membranes from freshwater-adapted animals. The addition of clonidine (1.0 micromol l-1 serosal side) started to inhibit Cl- current after 40-60 s; immediately before this, at 30 s, there was a significant rise (P<0.05, N=14) in tissue inositol 1,4,5, -trisphosphate (InsP3) level, but no change at later times, compared with LiCl-treated control membranes and measured by radiolabeled receptor assay. The results indicate that seawater-adapted killifish can decrease their Cl- secretion rate through the action of the sympathetic nervous system, a response appropriate for the entry of estuarine fish to fresh water, and that the effect is mediated by 2-adrenoceptors via InsP3. The results imply that euryhaline fish entering fresh water can undergo an autonomic reflex reduction in salt secretion that does not require a stress response.

Resource pulses in desert river habitats: productivity-biodiversity hotspots, or mirages?

PubMed

Free, Carissa L; Baxter, Greg S; Dickman, Christopher R; Leung, Luke K P

2013-01-01

Resource pulses in the world's hot deserts are driven largely by rainfall and are highly variable in both time and space. However, run-on areas and drainage lines in arid regions receive more water more often than adjacent habitats, and frequently sustain relatively high levels of primary productivity. These landscape features therefore may support higher biotic diversity than other habitats, and potentially act as refuges for desert vertebrates and other biota during droughts. We used the ephemeral Field River in the Simpson Desert, central Australia, as a case study to quantify how resources and habitat characteristics vary spatially and temporally along the riparian corridor. Levels of moisture and nutrients were greater in the clay-dominated soils of the riverine corridor than in the surrounding sand dunes, as were cover values of trees, annual grasses, other annual plants and litter; these resources and habitat features were also greater near the main catchment area than in the distal reaches where the river channel runs out into extensive dune fields. These observations confirm that the riverine corridor is more productive than the surrounding desert, and support the idea that it may act as a refuge or as a channel for the ingress of peri-desert species. However, the work also demonstrates that species diversity of invertebrates and plants is not higher within the river corridor; rather, it is driven by rainfall and the accompanying increase in annual plants following a rain event. Further research is required to identify the biota that depend upon these resource pulses.

Resource Pulses in Desert River Habitats: Productivity-Biodiversity Hotspots, or Mirages?

PubMed Central

Free, Carissa L.; Baxter, Greg S.; Dickman, Christopher R.; Leung, Luke K. P.

2013-01-01

Resource pulses in the world's hot deserts are driven largely by rainfall and are highly variable in both time and space. However, run-on areas and drainage lines in arid regions receive more water more often than adjacent habitats, and frequently sustain relatively high levels of primary productivity. These landscape features therefore may support higher biotic diversity than other habitats, and potentially act as refuges for desert vertebrates and other biota during droughts. We used the ephemeral Field River in the Simpson Desert, central Australia, as a case study to quantify how resources and habitat characteristics vary spatially and temporally along the riparian corridor. Levels of moisture and nutrients were greater in the clay-dominated soils of the riverine corridor than in the surrounding sand dunes, as were cover values of trees, annual grasses, other annual plants and litter; these resources and habitat features were also greater near the main catchment area than in the distal reaches where the river channel runs out into extensive dune fields. These observations confirm that the riverine corridor is more productive than the surrounding desert, and support the idea that it may act as a refuge or as a channel for the ingress of peri-desert species. However, the work also demonstrates that species diversity of invertebrates and plants is not higher within the river corridor; rather, it is driven by rainfall and the accompanying increase in annual plants following a rain event. Further research is required to identify the biota that depend upon these resource pulses. PMID:24124446

Diversity and Community Composition of Vertebrates in Desert River Habitats

PubMed Central

Free, C. L.; Baxter, G. S.; Dickman, C. R.; Lisle, A.; Leung, L. K.-P.

2015-01-01

Animal species are seldom distributed evenly at either local or larger spatial scales, and instead tend to aggregate in sites that meet their resource requirements and maximise fitness. This tendency is likely to be especially marked in arid regions where species could be expected to concentrate at resource-rich oases. In this study, we first test the hypothesis that productive riparian sites in arid Australia support higher vertebrate diversity than other desert habitats, and then elucidate the habitats selected by different species. We addressed the first aim by examining the diversity and composition of vertebrate assemblages inhabiting the Field River and adjacent sand dunes in the Simpson Desert, western Queensland, over a period of two and a half years. The second aim was addressed by examining species composition in riparian and sand dune habitats in dry and wet years. Vertebrate species richness was estimated to be highest (54 species) in the riverine habitats and lowest on the surrounding dune habitats (45 species). The riverine habitats had different species pools compared to the dune habitats. Several species, including the agamid Gowidon longirostris and tree frog Litoria rubella, inhabited the riverine habitats exclusively, while others such as the skinks Ctenotus ariadnae and C. dux were captured only in the dune habitats. The results suggest that, on a local scale, diversity is higher along riparian corridors and that riparian woodland is important for tree-dependent species. Further, the distribution of some species, such as Mus musculus, may be governed by environmental variables (e.g. soil moisture) associated with riparian corridors that are not available in the surrounding desert environment. We conclude that inland river systems may be often of high conservation value, and that management should be initiated where possible to alleviate threats to their continued functioning. PMID:26637127

Microbial Diversity in Soil, Sand Dune and Rock Substrates of the Thar Monsoon Desert, India.

PubMed

Rao, Subramanya; Chan, Yuki; Bugler-Lacap, Donnabella C; Bhatnagar, Ashish; Bhatnagar, Monica; Pointing, Stephen B

2016-03-01

A culture-independent diversity assessment of archaea, bacteria and fungi in the Thar Desert in India was made. Six locations in Ajmer, Jaisalmer, Jaipur and Jodhupur included semi-arid soils, arid soils, arid sand dunes, plus arid cryptoendolithic substrates. A real-time quantitative PCR approach revealed that bacteria dominated soils and cryptoendoliths, whilst fungi dominated sand dunes. The archaea formed a minor component of all communities. Comparison of rRNA-defined community structure revealed that substrate and climate rather than location were the most parsimonious predictors. Sequence-based identification of 1240 phylotypes revealed that most taxa were common desert microorganisms. Semi-arid soils were dominated by actinobacteria and alpha proteobacteria, arid soils by chloroflexi and alpha proteobacteria, sand dunes by ascomycete fungi and cryptoendoliths by cyanobacteria. Climatic variables that best explained this distribution were mean annual rainfall and maximum annual temperature. Substrate variables that contributed most to observed diversity patterns were conductivity, soluble salts, Ca(2+) and pH. This represents an important addition to the inventory of desert microbiota, novel insight into the abiotic drivers of community assembly, and the first report of biodiversity in a monsoon desert system.

Assessment of the salt tolerance and environmental biosafety of Eucalyptus camaldulensis harboring a mangrin transgene.

PubMed

Yu, Xiang; Kikuchi, Akira; Shimazaki, Takayoshi; Yamada, Akiyo; Ozeki, Yoshihiro; Matsunaga, Etsuko; Ebinuma, Hiroyasu; Watanabe, Kazuo N

2013-01-01

Increasing soil salinization of arable land has a major impact on the global ecosystem. One approach to increase the usable global forest area is to develop transgenic trees with higher tolerance to conditions of salt stress. An allene oxide cyclase homolog, mangrin, contains a core protein domain that enhances the salt tolerance of its host. We utilized this feature to develop improved salt-tolerant eucalyptus trees, by using transgenic Eucalyptus camaldulensis carrying the mangrin gene as a model. Since the Japanese government requires an environmental biosafety assessment for the surrounding biosphere, we performed experiments on trees grown in a special netted-house. This study examined the transgenic E. camaldulensis carrying the mangrin gene to assess the feasibility of using these transformants, and assessed their salt tolerance and environmental biosafety. We found that seven of 36 transgenic genotypes had significantly higher salt tolerance than non-transformants, and more importantly, that these plants had no significant impact on environmental biosafety. These results suggest that introduction of the mangrin gene may be one approach to safely enhance salt tolerance in genetically modified Eucalyptus species, and that the transformants have no apparent risks in terms of environmental biosafety. Thus, this study provides valuable information regarding the use of transgenic trees in situ.

Radiocarbon Records of Fossil Fuel Emissions From Urban Trees in the Greater Salt Lake Valley From Mid-Century to Present.

NASA Astrophysics Data System (ADS)

Chritz, K.; Buchert, M.; Walker, J. C.; Mendoza, D.; Pataki, D. E.; Xu, X.; Lin, J. C.

2017-12-01

Generating long term records of fossil fuel emissions of urban environments is complicated by the fact that direct observations of emissions and urban atmospheric CO2 concentrations were only collected in the recent past. Radiocarbon (14C) in tree rings from urban trees can provide archives of fossil fuel emissions that may track population growth over time, as higher population density is typically correlated with increased vehicular traffic and associated CO2 emissions, which are radiocarbon dead. We present radiocarbon measurements (n=125) from five roadside green ash trees (Fraxinus pennsylvanica) located in three cities of northern Utah - Salt Lake City (urban, 2016 population: 193,744), Logan City (agricultural, 2016 population: 49,110) and Heber (rural, 2016 population: 14,969). Urban trees were cored in four cardinal directions and ring widths were measured and counted to establish a chronology. One ring from every third year in a single core from each tree was removed and holocellulose was extracted from bulk wood of individual rings for 14C analysis. Fraction CO2 from fossil fuel burning (CO2-ff) was calculated using a simple mass-balance calculation from measured 14C values and remote background atmospheric 14CO2 values for NH Zone 2. The data from all three cities indicate a general trend of increasing CO2-ff uptake by the trees from 1980s to present, as expected with increased population growth and vehicular traffic. However, records in all three cities show unique elevated CO2-ff prior to the 1980s, assuming similar climate patterns through time, diverging from historic population size. We employed atmospheric simulations from the STILT (Stochastic Time-Inverted Lagrangian Transport) models for each of these trees to create footprints to determine source areas for CO2. These footprints reveal that atmospheric sampling areas can be large for certain trees, and other sources of 14C dead carbon, such as coal and natural gas from industrial emissions

Directional floral orientation in Joshua trees (Yucca brevifolia)

Treesearch

Steve Warren; L. Scott Baggett; Heather Warren

2016-01-01

Joshua tree (Yucca brevifolia Engelm.) is a large, arborescent member of the yucca genus. It is an endemic and visually dominant plant in portions of the Mojave Desert, USA. We document the unique and heretofore unreported directional orientation of its flower panicles. The flower panicles grow primarily at the tips of branches that are oriented to the south....

Seaweeds and halophytes to remove carbon from the atmosphere

DOE Office of Scientific and Technical Information (OSTI.GOV)

Glenn, E.P.; Kent, K.J.; Thompson, T.L.

1991-02-01

The utility industry and other interested parties have investigated strategies to mitigate the buildup of atmospheric CO{sub 2}. One option that has been considered is the planting of trees on a massive scale to absorb carbon through photosynthesis. A dilemma of using tree plantations, however, is that they might occupy land that will be needed for food production or other needs for an expected doubling of human population in the tropical regions. We evaluated seaweeds and salt-tolerant terrestrial plants (halophytes) to be grown on the coastal shelves and salt deserts of the world as possible alternatives to tree plantations. Anmore » estimated 1.3 {times} 10{sup 6} km{sup 2} of continental shelf and 1.3 {times} 10{sup 6} km{sup 2} of salt desert may be usable for seaweed and halophyte plantations. The production rates of managed seaweed and halophyte plantings are similar to managed tree plantations. Seaweeds and halophytes could conceivably absorb 10--20% of annual fossil fuel carbon emissions through biomass production, similar to estimates made for tree plantations. Present costs of halophyte biomass production are similar to costs of tree biomass production, whereas seaweed biomass is much more expensive to produce using existing technologies. Storage of seaweed carbon might be accomplished by allowing it to enter the sediment detritus chain whereas halophyte carbon might be sequestered in the soil, or used as biomass fuel. As has been concluded for reforestation, these saline biomass crops could at best help delay rather than solve the carbon dioxide build-up problem. 1 fig., 13 tabs.« less

Salt budget for West Pond, Utah, April 1987 to June 1989

USGS Publications Warehouse

Wold, S.R.; Waddell, K.M.

1994-01-01

During operation of the West Desert pumping project, April 10. 1987, to June 30, 1989, data were collected as part of a monitoring program to evaluate the effects of pumping brine from Great Salt Lake into West Pond in northern Utah. The removal of brine from Great Sail was part of an effort to lower the level of Great Salt Lake when the water level was at a high in 1986. These data were used to prepare a salt budget that indicates about 695 million tons of salt or about 14.2 percent of salt contained in Great Salt Lake was pumped into West Pond. Of the 695 million tons of salt pumped into West Pond, 315 million tons (45 percent) were dissolved in West Pond, 71 million tons (10.2 percent) formed a salt crust at the bottom of the pond, 10 million tons (1.4 percent) infiltrated the subsurface areas inundated by storage in the pond, 88 million tons (12.7 percent) were withdrawn by American Magnesium Corporation, and 123 million tons (17.7 percent) discharged from the pond through the Newfoundland weir. About 88 million tons (13 percent) of the salt pumped from the lake could not be accounted for in the salt budget. About 94 million tons of salt (1.9 percent of the total salt in Great Salt Lake) flowed back to Great Salt Lake.

A possible link between life and death of a xeric tree in desert.

PubMed

Xu, Gui-Qing; McDowell, Nate G; Li, Yan

2016-05-01

Understanding the interactions between drought and tree ontogeny or size remains an essential research priority because size-specific mortality patterns have large impacts on ecosystem structure and function, determine forest carbon storage capacity, and are sensitive to climatic change. Here we investigate a xerophytic tree species (Haloxylon ammodendron (C.A. Mey.)) with which the changes in biomass allocation with tree size may play an important role in size-specific mortality patterns. Size-related changes in biomass allocation, root distribution, plant water status, gas exchange, hydraulic architecture and non-structural carbohydrate reserves of this xerophytic tree species were investigated to assess their potential role in the observed U-shaped mortality pattern. We found that excessively negative water potentials (<-4.7MPa, beyond the P50leaf of -4.1MPa) during prolonged drought in young trees lead to hydraulic failure; while the imbalance of photoassimilate allocation between leaf and root system in larger trees, accompanied with declining C reserves (<2% dry matter across four tissues), might have led to carbon starvation. The drought-resistance strategy of this species is preferential biomass allocation to the roots to improve water capture. In young trees, the drought-resistance strategy is not well developed, and hydraulic failure appears to be the dominant driver of mortality during drought. With old trees, excess root growth at the expense of leaf area may lead to carbon starvation during prolonged drought. Our results suggest that the drought-resistance strategy of this xeric tree is closely linked to its life and death: well-developed drought-resistance strategy means life, while underdeveloped or overdeveloped drought-resistance strategy means death. Copyright © 2016 Elsevier GmbH. All rights reserved.

Physiology of bile secretion.

PubMed

Esteller, Alejandro

2008-10-07

The formation of bile depends on the structural and functional integrity of the bile-secretory apparatus and its impairment, in different situations, results in the syndrome of cholestasis. The structural bases that permit bile secretion as well as various aspects related with its composition and flow rate in physiological conditions will first be reviewed. Canalicular bile is produced by polarized hepatocytes that hold transporters in their basolateral (sinusoidal) and apical (canalicular) plasma membrane. This review summarizes recent data on the molecular determinants of this primary bile formation. The major function of the biliary tree is modification of canalicular bile by secretory and reabsorptive processes in bile-duct epithelial cells (cholangiocytes) as bile passes through bile ducts. The mechanisms of fluid and solute transport in cholangiocytes will also be discussed. In contrast to hepatocytes where secretion is constant and poorly controlled, cholangiocyte secretion is regulated by hormones and nerves. A short section dedicated to these regulatory mechanisms of bile secretion has been included. The aim of this revision was to set the bases for other reviews in this series that will be devoted to specific issues related with biliary physiology and pathology.

Operation Desert Shield

Science.gov Websites

Bureau Iraq invades Kuwait, Aug. 2, 1990. Operation Desert Shield begins, Aug. 7, 1990. First U.S. forces Operation Desert Shield-related U.S. death, Aug. 12, 1990. President George Bush authorizes first call-up of Bureau Operation Desert Storm and air war phase begins, 3 a.m., Jan. 17, 1991 (Jan. 16, 7 p.m. Eastern

On the salty side of life: molecular, physiological and anatomical adaptation and acclimation of trees to extreme habitats.

PubMed

Polle, Andrea; Chen, Shaoliang

2015-09-01

Saline and sodic soils that cannot be used for agriculture occur worldwide. Cultivating stress-tolerant trees to obtain biomass from salinized areas has been suggested. Various tree species of economic importance for fruit, fibre and timber production exhibit high salinity tolerance. Little is known about the mechanisms enabling tree crops to cope with high salinity for extended periods. Here, the molecular, physiological and anatomical adjustments underlying salt tolerance in glycophytic and halophytic model tree species, such as Populus euphratica in terrestrial habitats, and mangrove species along coastlines are reviewed. Key mechanisms that have been identified as mediating salt tolerance are discussed at scales from the genetic to the morphological level, including leaf succulence and structural adjustments of wood anatomy. The genetic and transcriptomic bases for physiological salt acclimation are salt sensing and signalling networks that activate target genes; the target genes keep reactive oxygen species under control, maintain the ion balance and restore water status. Evolutionary adaptation includes gene duplication in these pathways. Strategies for and limitations to tree improvement, particularly transgenic approaches for increasing salt tolerance by transforming trees with single and multiple candidate genes, are discussed. © 2014 John Wiley & Sons Ltd.

Mate desertion in the snail kite

USGS Publications Warehouse

Beissinger, S.R.; Snyder, N.F.R.

1988-01-01

Mate desertion during the breeding cycle was documented at 28 of 36 (78%) snail kite, Rostrhamus sociabilis nests in Florida between 1979 and 1983. Offspring mortality occurred at only one deserted nest, however. Parents that were deserted by their mates continued to care for their young until independence (3?5 additional weeks) and provided snails at a rate similar to that of both parents combined before desertion. Males and females deserted with nearly equal frequency, except in 1982 when more females deserted. No desertion occurred during drought years, whereas desertion occurred at nearly every nest during favourable conditions. The occurrence of mate desertion was generally related to indirect measures of snail abundance: foraging range, snail delivery rates to the young and growth rates. Small broods were deserted more frequently by females than by males and tended to be deserted earlier than large ones. After desertion, deserters had the opportunity to re-mate and nest again since breeding seasons were commonly lengthy, but whether they did so was impossible to determine conclusively in most cases. The deserted bird sometimes incurred increased energetic costs and lost breeding opportunities during periods of monoparental care.

Navajo Code Talker Joe Morris, Sr. shared insights from his time as a secret World War Two messenger

NASA Technical Reports Server (NTRS)

2002-01-01

Navajo Code Talker Joe Morris, Sr. shared insights from his time as a secret World War Two messenger with his audience at NASA's Dryden Flight Research Center on Nov. 26, 2002. NASA Dryden is located on Edwards Air Force Base in California's Mojave Desert.

Deserts : geology and resources

USGS Publications Warehouse

Walker, Alta S.

1996-01-01

Approximately one-third of the Earth's land surface is desert, arid land with meager rainfall that supports only sparse vegetation and a limited population of people and animals. Deserts stark, sometimes mysterious worlds have been portrayed as fascinating environments of adventure and exploration from narratives such as that of Lawrence of Arabia to movies such as "Dune." These arid regions are called deserts because they are dry. They may be hot, they may be cold. They may be regions of sand or vast areas of rocks and gravel peppered with occasional plants. But deserts are always dry. Deserts are natural laboratories in which to study the interactions of wind and sometimes water on the arid surfaces of planets. They contain valuable mineral deposits that were formed in the arid environment or that were exposed by erosion. Because deserts are dry, they are ideal places for human artifacts and fossils to be preserved. Deserts are also fragile environments. The misuse of these lands is a serious and growing problem in parts of our world.

Removal of chromium by some multipurpose tree seedlings of Indian thar desert.

PubMed

Mathur, Nishi; Singh, Joginder; Bohra, Sachendra; Bohra, Avinash; Vyas, Anil

2010-01-01

An experiment was conducted to study the potential of chromium (Cr) phytoaccumulatory capabilities of four tree species viz., Anogeissus latifolia, Terminalia arjuna, Tecomella undulata, and Salvadora persica Possibility of enhancement of Cr uptake by citric acid and vesicular arbuscular mycorrhizal fungi (VAM) amendments were also tried. Cr is a major pollutant of the environment. Chromium can exist in oxidation states from III to VI, but the most stable and common forms of Cr are trivalent and hexavalent species. Cr(VI) was more toxic to the tree growth in terms of collar diameter (CD) increment in all the tree species than Cr(lll). Roots accumulated more Cr than shoots in all the tree species. There was more than 10 fold increase in root Cr content in comparison with shoot Cr content in all the trees at all the concentration of Cr and all sources of Cr. Citric acid significantly increased the Cr content in the tissues of roots in all the species under both speciation of Cr. The highest increase in Cr content brought by 20 mM citric acid addition was in A. latifolia Results suggest that Anogeissus latifolia is a potential Cr accumulator with citric acid as soil amendment.

Exercise Desert Rock, Staff Memorandums. Army, Camp Desert Rock, Nevada.

DTIC Science & Technology

1957-01-01

I AD-AGAG 257 EXERCISE DESERT ROCK LAS VEGAS NV F/6 IS/ 3 EXERCISE DESERT ROCK, STAFF MEMORANDUMS. ARMY. CAMP DESERT ROCK-ETClUlCASIFE mm95i mm... Exercise Safety Progra - . 1. PUrose: To establish ane’ffective safety progr.Rm toreduce, and keep to a minimum, accident,1 manpower and monetary losses. at...agencies will be- followed. Supervispry personnel will: become familiar with those that Pre applicable to thei£r... operations. The Exercise Safety

Bile salt induced back diffusion of hydrogen ions across gastric mucosa in man. Fact or fiction?

PubMed

Ivey, K J

1981-01-01

We studied the effect of 5.5 mM bile salts, consisting of taurine conjugates in 5 normal subjects. Bile salts caused a significant increase in H+ loss from and Na+ movement into the gastric lumen (controls 1.5 mEq H+, 1.5 mEq Na+; bile salts -3.1 mEq H+ (p less than 0.001), Na+ 2.5 mEq (p less than 0.01) per 15 min.) To determine the effect of acid secretion, studies were repeated after i.v. atropine 2 mg/70 kg b.w. Atropine reduced net H+ flux to -0.2 mEq and Na+ gain to 0.9 mEq. When the bile salt studies were repeated after i.v. atropine, net H+ loss was increased to -5.4 mEq H+, significantly greater than with bile salts alone; corresponding Na+ gain was 3.2 mEq/15 min. The volume of fluid secreted was 25.0 ml in the bile salt study compared with 14.0 ml in the atropine and bile salt study. Even if all the additional volume 'secreted' (14 ml) were bicarbonate from the stomach or pancreatic juice with a concentration of 145 mEq/liter, it could account for a loss of only 2.0 mEq H+. In conclusion, atropine with bile salts is associated with a loss of H+ ions too great to be accounted for by bicarbonate neutralization. We conclude that back diffusion of H+ ions is the most likely explanation of H+ loss after bile salts in man.

Selected hydrologic data for the Bonneville Salt Flats and Pilot Valley, western Utah, 1991-93

USGS Publications Warehouse

Mason, James L.; Brothers, William C.; Gerner, Linda J.; Muir, Pamela S.

1995-01-01

This report contains hydrologic data collected during 1991-93 in the Bonneville Salt Flats and Pilot Valley study area of western Utah. These data were collected in cooperation with the U.S. Department of the Interior, Bureau of Land Management, as part of a study to investigate possible salt loss from the Bonneville Salt Flats. The Bonneville Salt Flats and adjacent Pilot Valley are located in the western part of the Great Salt Lake Desert in Utah, near the Nevada border. The Bonneville Salt Flats playa has a thick, perennial salt crust and the Pilot Valley playa has a thin, ephemeral salt crust. Well-completion data, including well depth and screened intervals, are presented in this report for selected shallow and deep monitoring wells. Water-level measurements are reported with corresponding specfic-gravity and temperature measurements. Results of chemical analyses are reported for brine collected from wells and pore fluids extracted from cores.

On the Biogeography of Centipeda: A Species-Tree Diffusion Approach

PubMed Central

Nylinder, Stephan; Lemey, Philippe; De Bruyn, Mark; Suchard, Marc A.; Pfeil, Bernard E.; Walsh, Neville; Anderberg, Arne A.

2014-01-01

Reconstructing the biogeographic history of groups present in continuous arid landscapes is challenging due to the difficulties in defining discrete areas for analyses, and even more so when species largely overlap both in terms of geography and habitat preference. In this study, we use a novel approach to estimate ancestral areas for the small plant genus Centipeda. We apply continuous diffusion of geography by a relaxed random walk where each species is sampled from its extant distribution on an empirical distribution of time-calibrated species-trees. Using a distribution of previously published substitution rates of the internal transcribed spacer (ITS) for Asteraceae, we show how the evolution of Centipeda correlates with the temporal increase of aridity in the arid zone since the Pliocene. Geographic estimates of ancestral species show a consistent pattern of speciation of early lineages in the Lake Eyre region, with a division in more northerly and southerly groups since ∼840 ka. Summarizing the geographic slices of species-trees at the time of the latest speciation event (∼20 ka), indicates no presence of the genus in Australia west of the combined desert belt of the Nullabor Plain, the Great Victoria Desert, the Gibson Desert, and the Great Sandy Desert, or beyond the main continental shelf of Australia. The result indicates all western occurrences of the genus to be a result of recent dispersal rather than ancient vicariance. This study contributes to our understanding of the spatiotemporal processes shaping the flora of the arid zone, and offers a significant improvement in inference of ancestral areas for any organismal group distributed where it remains difficult to describe geography in terms of discrete areas. PMID:24335493

Topographic influences on vegetation mosaics and tree diversity in the Chihuahuan Desert Borderlands.

PubMed

Poulos, Helen M; Camp, Ann E

2010-04-01

The abundance and distribution of species reflect how the niche requirements of species and the dynamics of populations interact with spatial and temporal variation in the environment. This study investigated the influence of geographical variation in environmental site conditions on tree dominance and diversity patterns in three topographically dissected mountain ranges in west Texas, USA, and northern Mexico. We measured tree abundance and basal area using a systematic sampling design across the forested areas of three mountain ranges and related these data to a suite of environmental parameters derived from field and digital elevation model data. We employed cluster analysis, classification and regression trees (CART), and rarefaction to identify (1) the dominant forest cover types across the three study sites and (2) environmental influences on tree distribution and diversity patterns. Elevation, topographic position, and incident solar radiation were the major influences on tree dominance and diversity. Mesic valley bottoms hosted high-diversity vegetation types, while hotter and drier mid-slopes and ridgetops supported lower tree diversity. Valley bottoms and other topographic positions shared few species, indicating high species turnover at the landscape scale. Mountain ranges with high topographic complexity also had higher species richness, suggesting that geographical variability in environmental conditions was a major influence on tree diversity. This study stressed the importance of landscape- and regional-scale topographic variability as a key factor controlling vegetation pattern and diversity in southwestern North America.

In situ metabolism in halite endolithic microbial communities of the hyperarid Atacama Desert

PubMed Central

Davila, Alfonso F.; Hawes, Ian; Araya, Jonathan G.; Gelsinger, Diego R.; DiRuggiero, Jocelyne; Ascaso, Carmen; Osano, Anne; Wierzchos, Jacek

2015-01-01

The Atacama Desert of northern Chile is one of the driest regions on Earth, with areas that exclude plants and where soils have extremely low microbial biomass. However, in the driest parts of the desert there are microorganisms that colonize the interior of halite nodules in fossil continental evaporites, where they are sustained by condensation of atmospheric water triggered by the salt substrate. Using a combination of in situ observations of variable chlorophyll fluorescence and controlled laboratory experiments, we show that this endolithic community is capable of carbon fixation both through oxygenic photosynthesis and potentially ammonia oxidation. We also present evidence that photosynthetic activity is finely tuned to moisture availability and solar insolation and can be sustained for days, and perhaps longer, after a wetting event. This is the first demonstration of in situ active metabolism in the hyperarid core of the Atacama Desert, and it provides the basis for proposing a self-contained, endolithic community that relies exclusively on non-rainfall sources of water. Our results contribute to an increasing body of evidence that even in hyperarid environments active metabolism, adaptation, and growth can occur in highly specialized microhabitats. PMID:26500612

In situ metabolism in halite endolithic microbial communities of the hyperarid Atacama Desert.

PubMed

Davila, Alfonso F; Hawes, Ian; Araya, Jonathan G; Gelsinger, Diego R; DiRuggiero, Jocelyne; Ascaso, Carmen; Osano, Anne; Wierzchos, Jacek

2015-01-01

The Atacama Desert of northern Chile is one of the driest regions on Earth, with areas that exclude plants and where soils have extremely low microbial biomass. However, in the driest parts of the desert there are microorganisms that colonize the interior of halite nodules in fossil continental evaporites, where they are sustained by condensation of atmospheric water triggered by the salt substrate. Using a combination of in situ observations of variable chlorophyll fluorescence and controlled laboratory experiments, we show that this endolithic community is capable of carbon fixation both through oxygenic photosynthesis and potentially ammonia oxidation. We also present evidence that photosynthetic activity is finely tuned to moisture availability and solar insolation and can be sustained for days, and perhaps longer, after a wetting event. This is the first demonstration of in situ active metabolism in the hyperarid core of the Atacama Desert, and it provides the basis for proposing a self-contained, endolithic community that relies exclusively on non-rainfall sources of water. Our results contribute to an increasing body of evidence that even in hyperarid environments active metabolism, adaptation, and growth can occur in highly specialized microhabitats.

Microbiome analysis and bacterial isolation from Lejía Lake soil in Atacama Desert.

PubMed

Mandakovic, Dinka; Maldonado, Jonathan; Pulgar, Rodrigo; Cabrera, Pablo; Gaete, Alexis; Urtuvia, Viviana; Seeger, Michael; Cambiazo, Verónica; González, Mauricio

2018-07-01

As a consequence of the severe climatic change affecting our entire world, many lakes in the Andes Cordillera are likely to disappear within a few decades. One of these lakes is Lejía Lake, located in the central Atacama Desert. The objectives of this study were: (1) to characterize the bacterial community from Lejía Lake shore soil (LLS) using 16S rRNA sequencing and (2) to test a culture-based approach using a soil extract medium (SEM) to recover soil bacteria. This extreme ecosystem was dominated by three phyla: Bacteroidetes, Proteobacteria, and Firmicutes with 29.2, 28.2 and 28.1% of the relative abundance, respectively. Using SEM, we recovered 7.4% of the operational taxonomic units from LLS, all of which belonged to the same three dominant phyla from LLS (6.9% of Bacteroidetes, 77.6% of Proteobacteria, and 15.3% of Firmicutes). In addition, we used SEM to recover isolates from LLS and supplemented the culture medium with increasing salt concentrations to isolate microbial representatives of salt tolerance (Halomonas spp.). The results of this study complement the list of microbial taxa diversity from the Atacama Desert and assess a pipeline to isolate selective bacteria that could represent useful elements for biotechnological approaches.

Spatial and temporal variation in tree-ring α-cellulose oxygen and hydrogen isotope values as a record of water availability in the Atacama Desert

NASA Astrophysics Data System (ADS)

Olson, E. J.; Dodd, J. P.

2015-12-01

Previous studies have documented that tree ring oxygen and hydrogen isotopes primarily reflect source water; however, biosynthetic fractionation processes modify this signal and can have a varied response to environmental conditions. The degree to which source water contributes to δ2H and δ18O values of plant α-cellulose is species-specific and modern calibration studies are necessary. Here we present a calibration data set of P. tamarugo α-cellulose δ2H and δ18O values from the Atacama Desert in Northern Chile. P. tamarugo trees are endemic to the region and have adapted to the extremely arid environment where average annual precipitation is < 5mm/yr. This modern isotope chronology has been constructed from living P. tamarugo trees (n=12) from the Pampa del Tamarugal Basin in the northern Atacama. Generally, the tree-ring α-cellulose δ18O values are poorly correlated with meteorological data from coastal stations (i.e. Iquique); however, there is good agreement between regional groundwater depth and α-cellulose δ18O values. Most notably, average α-cellulose δ18O values increase by >2 ‰ over the past 20 years associated with a ~1.1 m lowering of the local groundwater table throughout the area. The correlation between a-cellulose isotope values and hydrologic conditions in modern times provides a baseline for interpretation of tree-ring isotope chronologies from the past 9.5 kya. A high-resolution Holocene (1.8-9.1 kya) age record of Prosopis sp. tree ring α-cellulose δ18O values provides a proxy for climatic and hydrologic conditions. During the early Holocene δ18O values range from 31 to 35‰ (2σ=0.58‰), while during the late Holocene values are much more variable (27.4 to 41‰; 2σ=2.64‰). Anthropogenic demand on local water sources is the most significant environmental factor affecting the variation in modern α-cellulose δ18O values; however, climate induced changes in regional water availability are the dominant driver of variability

Role of Vasopressin in Rat Models of Salt-Dependent Hypertension.

PubMed

Prager-Khoutorsky, Masha; Choe, Katrina Y; Levi, David I; Bourque, Charles W

2017-05-01

Dietary salt intake increases both plasma sodium and osmolality and therefore increases vasopressin (VP) release from the neurohypophysis. Although this effect could increase blood pressure by inducing fluid reabsorption and vasoconstriction, acute activation of arterial baroreceptors inhibits VP neurons via GABA A receptors to oppose high blood pressure. Here we review recent findings demonstrating that this protective mechanism fails during chronic high salt intake in rats. Two recent studies showed that chronic high sodium intake causes an increase in intracellular chloride concentration in VP neurons. This effect causes GABA A receptors to become excitatory and leads to the emergence of VP-dependent hypertension. One study showed that the increase in intracellular chloride was provoked by a decrease in the expression of the chloride exporter KCC2 mediated by local secretion of brain-derived neurotrophic factor and activation of TrkB receptors. Prolonged high dietary salt intake can cause pathological plasticity in a central homeostatic circuit that controls VP secretion and thereby contribute to peripheral vasoconstriction and hypertension.

Salts in the dry valleys of Antartica

NASA Technical Reports Server (NTRS)

Gibson, E. K., Jr.; Presley, B. J.; Hatfield, J.

1984-01-01

The Dry Valleys of Antarctica are examples of polar deserts which are rare geological features on the Earth. Such deserts typically have high salinities associated with their closed-basin waters and on many surficial materials throughout them. In order to examine the possible sources for the salts observed in association with the soils in the Dry Valleys. The chloride and bromide concentrations of the water leachates from 58 soils and core samples were measured. The Cl/Br ratio for seawater is 289 and ratios measured for most of the 58 soils studied (greater than 85% of the soils studied) was larger than the seawater ratio (ratios typically were greater than 1000 and ranged up to 50,000). The enrichment in Cl relative to Br is strong evidence that the alts present within the soils were derived from seawater during ordinary evaporation processes, and not from the deposition of Cl and Br from aerosols or from rock weathering as has often been suggested.

Effects of desert wildfires on desert tortoise (Gopherus agassizii) and other small vertebrates

USGS Publications Warehouse

Esque, T.C.; Schwalbe, C.R.; DeFalco, L.A.; Duncan, R.B.; Hughes, T.J.

2003-01-01

We report the results of standardized surveys to determine the effects of wildfires on desert tortoises (Gopherus agassizii) and their habitats in the northeastern Mojave Desert and northeastern Sonoran Desert. Portions of 6 burned areas (118 to 1,750 ha) were examined for signs of mortality of vertebrates. Direct effects of fire in desert habitats included animal mortality and loss of vegetation cover. A range of 0 to 7 tortoises was encountered during surveys, and live tortoises were found on all transects. In addition to desert tortoises, only small (<1 kg) mammals and reptiles (11 taxa) were found dead on the study areas. We hypothesize that indirect effects of fire on desert habitats might result in changes in the composition of diets and loss of vegetation cover, resulting in an increase in predation and loss of protection from temperature extremes. These changes in habitat also might cause changes in vertebrate communities in burned areas.

Deficit irrigation of a landscape halophyte for reuse of saline waste water in a desert city

USGS Publications Warehouse

Glenn, E.P.; Mckeon, C.; Gerhart, V.; Nagler, P.L.; Jordan, F.; Artiola, J.

2009-01-01

Saline waste waters from industrial and water treatment processes are an under-utilized resource in desert urban environments. Management practices to safely use these water sources are still in development. We used a deeprooted native halophyte, Atriplex lentiformis (quailbush), to absorb mildly saline effluent (1800 mg l-1 total dissolved solids, mainly sodium sulfate) from a water treatment plant in the desert community of Twentynine Palms, California. We developed a deficit irrigation strategy to avoid discharging water past the root zone to the aquifer. The plants were irrigated at about one-third the rate of reference evapotranspiration (ETo) calculated from meteorological data over five years and soil moisture levels were monitored to a soil depth of 4.7 m at monthly intervals with a neutron hydroprobe. The deficit irrigation schedule maintained the soil below field capacity throughout the study. Water was presented on a more or less constant schedule, so that the application rates were less than ETo in summer and equal to or slightly greater than ETo in winter, but the plants were able to consume water stored in the profile in winter to support summer ET. Sodium salts gradually increased in the soil profile over the study but sulfate levels remained low, due to formation of gypsum in the calcic soil. The high salt tolerance, deep roots, and drought tolerance of desert halophytes such as A. lentiformis lend these plants to use as deficit-irrigated landscape plants for disposal of effluents in urban setting when protection of the aquifer is important. ?? 2008 Elsevier B.V.

AIS spectra of desert shrub canopies

NASA Technical Reports Server (NTRS)

Murray, R.; Isaacson, D. L.; Schrumpf, B. J.; Ripple, W. J.; Lewis, A. J.

1986-01-01

Airborne Imaging Spectrometer (AIS) data were collected 30 August 1985 from a desert shrub community in central Oregon. Spectra from artificial targets placed on the test site and from bare soil, big sagebrush (Artemesia tridentata wyomingensis), silver sagebrush (Artemesia cana bolander), and exposed volcanic rocks were studied. Spectral data from grating position 3 (tree mode) were selected from 25 ground positions for analysis by Principal Factor Analysis (PFA). In this grating position, as many as six factors were identified as significant in contributing to spectral structure. Channels 74 through 84 (tree mode) best characterized between-class differences. Other channels were identified as nondiscriminating and as associated with such errors as excessive atmospheric absorption and grating positin changes. The test site was relatively simple with the two species (A. tridentata and A. cana) representing nearly 95% of biomass and with only two mineral backgrounds, a montmorillonitic soil and volcanic rocks. If, as in this study, six factors of spectral structure can be extracted from a single grating position from data acquired over a simple vegetation community, then AIS data must be considered rich in information-gathering potential.

High-quality permanent draft genome sequence of Ensifer sp. PC2, isolated from a nitrogen-fixing root nodule of the legume tree (Khejri) native to the Thar Desert of India

DOE PAGES

Gehlot, Hukam Singh; Ardley, Julie; Tak, Nisha; ...

2016-06-23

Ensifer sp. PC2 is an aerobic, motile, Gram-negative, non-spore-forming rod that was isolated from a nitrogen-fixing nodule of the tree legume P. cineraria (L.) Druce (Khejri), which is a keystone species that grows in arid and semi-arid regions of the Indian Thar desert. Strain PC2 exists as a dominant saprophyte in alkaline soils of Western Rajasthan. It is fast growing, well-adapted to arid conditions and is able to form an effective symbiosis with several annual crop legumes as well as species of mimosoid trees and shrubs. Here we describe the features of Ensifer sp. PC2, together with genome sequence informationmore » and its annotation. The 8,458,965 bp high-quality permanent draft genome is arranged into 171 scaffolds of 171 contigs containing 8,344 protein-coding genes and 139 RNA-only encoding genes, and is one of the rhizobial genomes sequenced as part of the DOE Joint Genome Institute 2010 Genomic Encyclopedia for Bacteria and Archaea-Root Nodule Bacteria (GEBA-RNB) project proposal.« less

High-quality permanent draft genome sequence of Ensifer sp. PC2, isolated from a nitrogen-fixing root nodule of the legume tree (Khejri) native to the Thar Desert of India

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gehlot, Hukam Singh; Ardley, Julie; Tak, Nisha

Ensifer sp. PC2 is an aerobic, motile, Gram-negative, non-spore-forming rod that was isolated from a nitrogen-fixing nodule of the tree legume P. cineraria (L.) Druce (Khejri), which is a keystone species that grows in arid and semi-arid regions of the Indian Thar desert. Strain PC2 exists as a dominant saprophyte in alkaline soils of Western Rajasthan. It is fast growing, well-adapted to arid conditions and is able to form an effective symbiosis with several annual crop legumes as well as species of mimosoid trees and shrubs. Here we describe the features of Ensifer sp. PC2, together with genome sequence informationmore » and its annotation. The 8,458,965 bp high-quality permanent draft genome is arranged into 171 scaffolds of 171 contigs containing 8,344 protein-coding genes and 139 RNA-only encoding genes, and is one of the rhizobial genomes sequenced as part of the DOE Joint Genome Institute 2010 Genomic Encyclopedia for Bacteria and Archaea-Root Nodule Bacteria (GEBA-RNB) project proposal.« less

Effects of added Zn, Ni and Cd on desert shrubs grown in desert soil

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patel, P.M.; Wallace, A.; Romney, E.M.

1980-01-01

Desert shrubs - Ambrosia dumosa, Lycium andersonii, Larrea tridenata, and Ephedra nevadensis wre grown in a glasshouse in desert (calcarous) soil with different levels of added Zn, Ni, and Cd. The objective was to study effects of the metals on growth and yield and uptake and translocation of metals in desert plant species which are common in the Mojave Desert (areas of Nevada and southeast California). Zinc and Cd considerably decreased yields of all four species. Yields of E. nevadensis were increased by Ni at 250 and 500 mg/kg applied to desert soil. Ephedra nevadensis was more tolerant of Nimore » than were the other three desert shrubs. Some interactions were observed among various elements: manganese concentration was increased in shrubs by Zn. Particularly, application of Ni reduced the concentrations of Zn and Mn over the control.« less

Lut Desert, Iran

NASA Technical Reports Server (NTRS)

1981-01-01

Iran is a large country with several desert regions. In the Dasht-E-Lut (Lut Desert) (30.5N, 58.5E) an area known as Namak-Zar, about 100 miles east of the city of Kerman, is at the center of this photograph. Some of the world's most prominent Yardangs (very long, parallel ridges and depressions) have been wind eroded in these desert dry lake bed sediments. At the left of the photo is a large field of sand dunes at right angles to the wind.

Livestock grazing and the desert tortoise in the Mojave Desert

USGS Publications Warehouse

Oldemeyer, John L.

1994-01-01

A large part of the Mojave Desert is not in pristine condition, and some current conditions can be related to past grazing-management practices. No information could be found on densities of the desert tortoise (Gopherus agassizii) or on vegetative conditions of areas that had not been grazed to allow managers a comparison of range conditions with data on tortoises. Experimental information to assess the effect of livestock grazing on tortoises is lacking, and researchers have not yet examined whether the forage that remains after grazing is sufficient to meet the nutritional needs of desert tortoises.

Selection for salt tolerance in tidal freshwater swamp species: Advances using baldcypress as a model for restoration: Chapter 14

USGS Publications Warehouse

Krauss, Ken W.; Chambers, Jim L.; Creech, David L.

2007-01-01

Worldwide, the intrusion of salinity into irrigated and natural landscapes has major economic and cultural impacts and has resulted in large reductions in crop yields (Epstein et al. 1980; Flowers 2003). Losses have prompted wide-scale programs to improve the salt tolerance of many agronomic species or to identify crop species that can tolerate lands affected by low levels of salinity. Few historic research efforts have considered forest tree species in the United States, especially in nonurban areas. Newer programs have focused on identifying salt tolerance in forest tree species but have mainly limited these efforts to compiling lists of salt tolerant species to be used in afforestation projects (Gogate et al. 1984; Shrivastava et al. 1988; Beckmann 1991; Bell 1999). Gogate et al. (1984), for instance, listed 26 potential species from Australia with silvicultural application to salt affected lands in India. More comprehensive efforts have considered species lists along with specific site requirements (Bell 1999); species tolerant to saline irrigation waters on dry land, for example, will not often be tolerant of salinity increases in wetland settings. Similar ideas have spawned field trials of native and nonnative tree species in India, Pakistan, Thailand, Australia, and the United States (Thomson 1988; Beckmann 1991; Krauss et al. 2000; Conner and Ozalp 2002; Marcar and Crawford 2004; Conner and Inabinette 2005). Concerted attempts at salt tolerance improvement of forest tree species have been limited, owing in part to the diversity of regional issues that such programs must consider. Whereas food, fodder, and pulp yield may be the major improvement goal on salt affected lands in India (Mathur and Sharma 1984), identifying trees that can survive deicing salts (Townsend 1989), oil and gas brine discharges (Auchmoody and Walters 1988), or sea-level rise induced salinity changes (Pezeshki et al. 1987, 1990) are of greater interest to larger industrial nations

Calcium Sulfate in Atacama Desert Basalt: A Possible Analog for Bright Material in Adirondack Basalt, Gusev Crater

NASA Technical Reports Server (NTRS)

Sutter, B.; Golden, D. C.; Amundson, R.; Chong-Diaz, G.; Ming, D. W.

2007-01-01

The Atacama Desert in northern Chile is one of the driest deserts on Earth (< 2mm/y). The hyper-arid conditions allow extraordinary accumulations of sulfates, chlorides, and nitrates in Atacama soils. Examining salt accumulations in the Atacama may assist understanding salt accumulations on Mars. Recent work examining sulfate soils on basalt parent material observed white material in the interior vesicles of surface basalt. This is strikingly similar to the bright-white material present in veins and vesicles of the Adirondack basalt rocks at Gusev Crater which are presumed to consist of S, Cl, and/or Br. The abundance of soil gypsum/anhydrite in the area of the Atacama basalt suggested that the white material consisted of calcium sulfate (Ca-SO4) which was later confirmed by SEM/EDS analysis. This work examines the Ca-SO4 of Atacama basalt in an effort to provide insight into the possible nature of the bright material in the Adirondack basalt of Gusev Crater. The objectives of this work are to (i) discuss variations in Ca-SO4 crystal morphology in the vesicles and (ii) examine the Ca-SO4 interaction(s) with the basalt interior.

Desert Scrublands

USGS Publications Warehouse

Jones, L.L.C.; Halama, K.J.; Lovich, R.E.

2016-01-01

Desert scrublands comprise the lower to mid-elevation portions of four different ecosystems including the Chihuahuan, Great Basin, Mojave and Sonoran Deserts. Together the area inside their outer boundaries includes over 8% of the surface area of the United States. Despite significant differences in the flora and fauna of these bioregions they all share the common trait of being arid shrub-steppe ecosystems, receiving, on average, less than 254 mm of rain per year. The austere nature of these landscapes belies their significant biodiversity, the amazing behavioral and physiological adaptations of the biota, and the fragility of the ecosystems to human disturbances. For example, the Mojave Desert alone has at least 250 species of ephemeral plants, mostly winter annuals, and up to 90% are endemic.

Comparative behavioral and protein study of salivary secretions in Homalodisca spp. sharpshooters (Hemiptera: Cicadellidae: Cicadellinae)

USDA-ARS?s Scientific Manuscript database

A novel brush-induced method to physically stimulate salivation was applied to the glassy-winged and smoke tree sharpshooters. This technique enabled the direct observation of salivary secretion processes, solidification of saliva and for collection of salivary secretions. For both species, brush...

Distribution of desert varnish in Arizona

NASA Technical Reports Server (NTRS)

Elvidge, Christopher D.

1989-01-01

Desert varnish is the dark coat of clay and ferromanganese oxides developed on exposed rock surfaces in arid regions. It forms from the accretion of material from windblown dust. The distribution of desert varnish was mapped in Arizona. It was discovered that desert varnish could be mapped on a regional scale. Well developed desert varnish is common on stable rock surfaces in areas having alkaline soils and less than about 25 cm of annual precipitation. Rock surfaces in areas having more than 40 cm of annual precipitation are generally devoid of desert varnish. An experiment was conducted with varnished desert pavement stone. The stones were broken in half and half was set on a roof in central Illinois from April until October. Removed from the alkaline desert environment, it only took seven months for the varnish to develop an eroded appearance. This experiment graphically illustrates the dependency of desert varnish on alkalinity. In this context, the zones of eroded desert varnish in Arizona indicate that the area of active desert varnish formation has fluctuated, expanding in drier times and contracting/eroding in wetter times.

Carbon stocks in mangroves, salt marshes, and salt barrens in Tampa Bay, Florida, USA: Vegetative and soil characteristics.

NASA Astrophysics Data System (ADS)

Moyer, R. P.; Radabaugh, K.; Chappel, A. R.; Powell, C.; Bociu, I.; Smoak, J. M.

2017-12-01

When compared to other terrestrial environments, coastal "blue carbon" habitats such as salt marshes and mangrove forests sequester disproportionately large amounts of carbon as standing plant biomass and sedimentary peat deposits. This study quantified total carbon stocks in vegetation and soil of 17 salt marshes, salt barrens, and mangrove forests in Tampa Bay, Florida, USA. The sites included natural, restored, and created wetlands of varying ages and degrees of anthropogenic impacts. The average vegetative carbon stock in mangrove forests was 60.1 ± 2.7 Mg ha-1. Mangrove forests frequently consisted of a few large Avicennia germinans trees with smaller, abundant Rhizophora mangle and/or Laguncularia racemosa trees. The average vegetative carbon stock was 11.8 ± 3.7 Mg ha-1 for salt marshes and 2.0 ± 1.2 Mg ha-1 for salt barrens. Vegetative carbon did not significantly differ between natural and newly created salt marsh habitats, indicating that mature restored wetlands can be included with natural wetlands for the calculation of vegetative carbon in coastal blue carbon assessments. Peat deposits were generally less than 50 cm thick and organic content rapidly decreased with depth in all habitats. Soil in this study was analyzed in 1 cm intervals; the accuracy of subsampling or binning soil into depth intervals of 2-5 cm was also assessed. In most cases, carbon stock values obtained from these larger sampling intervals were not statistically different from values obtained from sampling at 1 cm intervals. In the first 15 cm, soil in mangrove forests contained an average of 15.1% organic carbon by weight, salt marshes contained 6.5%, and salt barrens contained 0.8%. Total carbon stock in mangroves was 187.1±17.3 Mg ha-1, with 68% of that carbon stored in soil. Salt marshes contained an average of 65.2±25.3 Mg ha-1 (82% soil carbon) and salt barrens had carbon stocks of 21.4±7.4 Mg ha-1 (89% soil carbon). These values were much lower than global averages for

Time-lapse electric resistivity in a stressed mangrove forest to image the role of the root zone in porewater salt distribution

NASA Astrophysics Data System (ADS)

Downs, C. M.; Krauss, K.; Kruse, S.

2017-12-01

The movement and storage of porewater salts is poorly understood in mangrove forests with limited surface water exchange between the forest and neighboring lagoon. These mangroves are often the most stressed, and have the most unfavorable salinity balance that often transition to mortality during extreme drought. A time-lapse resistivity survey was conducted in a stressed mangrove forest over a diel period. Resistivity is sensitive to the entire soil volume, including fine roots. The objective was to image changes in porewater salinity structures around both mangrove trees, where roots can be a prolific contributor to soil volume, and a salt pan with little or no vegetation. Throughout the diel period, salt pan conductivities remained relatively constant. The most significant temporal changes occur in the root zone around mangrove trees. Particularly interesting is a drop in resistivity (increased conductivity) at sunset when transpiration from individual trees decreases (or even ceases), potentially identifying a cumulative concentration of salts around the mangrove root zone after a full day of transpiration. The resistivity gradient decreases immediately after its peak at sunset, potentially identifying the consequences of hydraulic redistribution in diluting soils surrounding trees immediately after transpiration ceases. This is quicker than expected, and may imply a very strong and rapid eco-hydrological connection in the tree-facilitated salinity balance essential to their survival under the most salinity-stressed environments. At sunrise, resistivity increases, further suggesting dilution of salts via hydraulic redistribution of fresh water from the tree into the upper soil layers, or suggests an accumulation of salts within roots when presumably less water is moving through the trees. Repeated electric resistivity arrays provide spatial and temporal information about these salts and contribute to an overall understanding of how stressed mangrove forests

Estimating Natural Recharge in a Desert Environment Facing Increasing Ground-Water Demands

NASA Astrophysics Data System (ADS)

Nishikawa, T.; Izbicki, J. A.; Hevesi, J. A.; Martin, P.

2004-12-01

Ground water historically has been the sole source of water supply for the community of Joshua Tree in the Joshua Tree ground-water subbasin of the Morongo ground-water basin in the southern Mojave Desert. Joshua Basin Water District (JBWD) supplies water to the community from the underlying Joshua Tree ground-water subbasin, and ground-water withdrawals averaging about 960 acre-ft/yr have resulted in as much as 35 ft of drawdown. As growth continues in the desert, ground-water resources may need to be supplemented using imported water. To help meet future demands, JBWD plans to construct production wells in the adjacent Copper Mountain ground-water subbasin. To manage the ground-water resources and to identify future mitigating measures, a thorough understanding of the ground-water system is needed. To this end, field and numerical techniques were applied to determine the distribution and quantity of natural recharge. Field techniques included the installation of instrumented boreholes in selected washes and at a nearby control site. Numerical techniques included the use of a distributed-parameter watershed model and a ground-water flow model. The results from the field techniques indicated that as much as 70 acre-ft/yr of water infiltrated downward through the two principal washes during the study period (2001-3). The results from the watershed model indicated that the average annual recharge in the ground-water subbasins is about 160 acre-ft/yr. The results from the calibrated ground-water flow model indicated that the average annual recharge for the same area is about 125 acre-ft/yr. Although the field and numerical techniques were applied to different scales (local vs. large), all indicate that natural recharge in the Joshua Tree area is very limited; therefore, careful management of the limited ground-water resources is needed. Moreover, the calibrated model can now be used to estimate the effects of different water-management strategies on the ground

Chapter 22. Rosaceous shrubs

Treesearch

Nancy L. Shaw; Stephen B. Monsen; Richard Stevens

2004-01-01

Important shrubs of the Rose Family (Rosaceae) in the Intermountain region are distributed from blackbrush and salt desert shrub communities through high elevation forests and meadows. Growth habits of this group vary from trailing brambles to upright shrubs and small trees. Some species are evergreen while others are deciduous. Many of these species are highly valued...

Salt and essential hypertension: pathophysiology and implications for treatment.

PubMed

Garfinkle, Michael A

2017-06-01

Essential hypertension is common and is associated with significant morbidity and mortality. However, questions remain as to the exact physiological mechanisms underlying this disease. First, we discuss how essential hypertension may be largely a result of a maladaptation to a high-salt diet and that high blood pressure, rather than being an inactive side effect of high salt intake, may be an adaptive mechanism to improve salt secretion. Next, we explain how any physiological state that reduces urinary sodium concentrating ability may increase an individual's risk for salt-induced hypertension. Finally, we conclude that natriuresis is a crucial criterion for effective long-term pharmacologic treatment of essential hypertension. Copyright © 2017 American Society of Hypertension. Published by Elsevier Inc. All rights reserved.

Global Diversity of Desert Hypolithic Cyanobacteria.

PubMed

Lacap-Bugler, Donnabella C; Lee, Kevin K; Archer, Stephen; Gillman, Len N; Lau, Maggie C Y; Leuzinger, Sebastian; Lee, Charles K; Maki, Teruya; McKay, Christopher P; Perrott, John K; de Los Rios-Murillo, Asunción; Warren-Rhodes, Kimberley A; Hopkins, David W; Pointing, Stephen B

2017-01-01

Global patterns in diversity were estimated for cyanobacteria-dominated hypolithic communities that colonize ventral surfaces of quartz stones and are common in desert environments. A total of 64 hypolithic communities were recovered from deserts on every continent plus a tropical moisture sufficient location. Community diversity was estimated using a combined t-RFLP fingerprinting and high throughput sequencing approach. The t-RFLP analysis revealed desert communities were different from the single non-desert location. A striking pattern also emerged where Antarctic desert communities were clearly distinct from all other deserts. Some overlap in community similarity occurred for hot, cold and tundra deserts. A further observation was that the producer-consumer ratio displayed a significant negative correlation with growing season, such that shorter growing seasons supported communities with greater abundance of producers, and this pattern was independent of macroclimate. High-throughput sequencing of 16S rRNA and nif H genes from four representative samples validated the t-RFLP study and revealed patterns of taxonomic and putative diazotrophic diversity for desert communities from the Taklimakan Desert, Tibetan Plateau, Canadian Arctic and Antarctic. All communities were dominated by cyanobacteria and among these 21 taxa were potentially endemic to any given desert location. Some others occurred in all but the most extreme hot and polar deserts suggesting they were relatively less well adapted to environmental stress. The t-RFLP and sequencing data revealed the two most abundant cyanobacterial taxa were Phormidium in Antarctic and Tibetan deserts and Chroococcidiopsis in hot and cold deserts. The Arctic tundra displayed a more heterogenous cyanobacterial assemblage and this was attributed to the maritime-influenced sampling location. The most abundant heterotrophic taxa were ubiquitous among samples and belonged to the Acidobacteria, Actinobacteria, Bacteroidetes

Global Diversity of Desert Hypolithic Cyanobacteria

PubMed Central

Lacap-Bugler, Donnabella C.; Lee, Kevin K.; Archer, Stephen; Gillman, Len N.; Lau, Maggie C.Y.; Leuzinger, Sebastian; Lee, Charles K.; Maki, Teruya; McKay, Christopher P.; Perrott, John K.; de los Rios-Murillo, Asunción; Warren-Rhodes, Kimberley A.; Hopkins, David W.; Pointing, Stephen B.

2017-01-01

Global patterns in diversity were estimated for cyanobacteria-dominated hypolithic communities that colonize ventral surfaces of quartz stones and are common in desert environments. A total of 64 hypolithic communities were recovered from deserts on every continent plus a tropical moisture sufficient location. Community diversity was estimated using a combined t-RFLP fingerprinting and high throughput sequencing approach. The t-RFLP analysis revealed desert communities were different from the single non-desert location. A striking pattern also emerged where Antarctic desert communities were clearly distinct from all other deserts. Some overlap in community similarity occurred for hot, cold and tundra deserts. A further observation was that the producer-consumer ratio displayed a significant negative correlation with growing season, such that shorter growing seasons supported communities with greater abundance of producers, and this pattern was independent of macroclimate. High-throughput sequencing of 16S rRNA and nifH genes from four representative samples validated the t-RFLP study and revealed patterns of taxonomic and putative diazotrophic diversity for desert communities from the Taklimakan Desert, Tibetan Plateau, Canadian Arctic and Antarctic. All communities were dominated by cyanobacteria and among these 21 taxa were potentially endemic to any given desert location. Some others occurred in all but the most extreme hot and polar deserts suggesting they were relatively less well adapted to environmental stress. The t-RFLP and sequencing data revealed the two most abundant cyanobacterial taxa were Phormidium in Antarctic and Tibetan deserts and Chroococcidiopsis in hot and cold deserts. The Arctic tundra displayed a more heterogenous cyanobacterial assemblage and this was attributed to the maritime-influenced sampling location. The most abundant heterotrophic taxa were ubiquitous among samples and belonged to the Acidobacteria, Actinobacteria, Bacteroidetes

Does protection of desert tortoise habitat generate other ecological benefits in the Mojave Desert?

Treesearch

Matthew L. Brooks

2000-01-01

This paper summarizes the ecological effects of fenced habitat protection for the desert tortoise (Gopherus agassizii) at the Desert Tortoise Research Natural Area in the Mojave Desert. The following were higher inside than outside the natural area: (1) annual and perennial plant biomass, cover, diversity and dominance by natives, (2) soil seed...

Tree Crown Foliage Loss: A Mapping Survey on the Cumbrian Coast.

ERIC Educational Resources Information Center

Gilbertson, D. D.; Pyatt, F. B.

1980-01-01

An undergraduate student mapping survey of tree crown foliage loss is presented. Results suggest that the pattern and intensity of crown foliage loss of certain trees and shrubs in the Whitehaven area are affected by strong, salt-laden winds and air pollution. (CS)

76 FR 66354 - DesertXpress Enterprises, LLC and DesertXpress HSR Corporation-Construction and Operation...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-10-26

... DEPARTMENT OF TRANSPORTATION Surface Transportation Board [Docket No. FD 35544] DesertXpress Enterprises, LLC and DesertXpress HSR Corporation-- Construction and Operation Exemption--in Victorville, CA... requirements of 49 U.S.C. 10901 for DesertXpress Enterprises, LLC and its subsidiary (DXE) to build and operate...

Biogeochemical processes on tree islands in the greater everglades: Initiating a new paradigm

USGS Publications Warehouse

Wetzel, P.R.; Sklar, Fred H.; Coronado, C.A.; Troxler, T.G.; Krupa, S.L.; Sullivan, P.L.; Ewe, S.; Price, R.M.; Newman, S.; Orem, W.H.

2011-01-01

Scientists' understanding of the role of tree islands in the Everglades has evolved from a plant community of minor biogeochemical importance to a plant community recognized as the driving force for localized phosphorus accumulation within the landscape. Results from this review suggest that tree transpiration, nutrient infiltration from the soil surface, and groundwater flow create a soil zone of confluence where nutrients and salts accumulate under the head of a tree island during dry periods. Results also suggest accumulated salts and nutrients are flushed downstream by regional water flows during wet periods. That trees modulate their environment to create biogeochemical hot spots and strong nutrient gradients is a significant ecological paradigm shift in the understanding of the biogeochemical processes in the Everglades. In terms of island sustainability, this new paradigm suggests the need for distinct dry-wet cycles as well as a hydrologic regime that supports tree survival. Restoration of historic tree islands needs further investigation but the creation of functional tree islands is promising. Copyright ?? 2011 Taylor & Francis Group, LLC.

Active tectonics of the northern Mojave Desert: The 2017 Desert Symposium field trip road log

USGS Publications Warehouse

Miller, David; Reynolds, R.E.; Phelps, Geoffrey; Honke, Jeff; Cyr, Andrew J.; Buesch, David C.; Schmidt, Kevin M.; Losson, G.

2017-01-01

The 2017 Desert Symposium field trip will highlight recent work by the U.S. Geological Survey geologists and geophysicists, who have been mapping young sediment and geomorphology associated with active tectonic features in the least well-known part of the eastern California Shear Zone (ECSZ). This area, stretching from Barstow eastward in a giant arc to end near the Granite Mountains on the south and the Avawatz Mountains on the north (Fig. 1-1), encompasses the two major structural components of the ECSZ—east-striking sinistral faults and northwest-striking dextral faults—as well as reverseoblique and normal-oblique faults that are associated with topographic highs and sags, respectively. In addition, folds and stepovers (both restraining stepovers that form pop-up structures and releasing stepovers that create narrow basins) have been identified. The ECSZ is a segment in the ‘soft’ distributed deformation of the North American plate east of the San Andreas fault (Fig. 1-1), where it takes up approximately 20-25% of plate motion in a broad zone of right-lateral shear (Sauber et al., 1994) The ECSZ (sensu strictu) begins in the Joshua Tree area and passes north through the Mojave Desert, past the Owens Valley-to-Death Valley swath and northward, where it is termed the Walker Lane. It has been defined as the locus of active faulting (Dokka and Travis, 1990), but when the full history from about 10 Ma forward is considered, it lies in a broader zone of right shear that passes westward in the Mojave Desert to the San Andreas fault (Mojave strike-slip province of Miller and Yount, 2002) and passes eastward to the Nevada state line or beyond (Miller, this volume).We will visit several accessible highlights for newly studied faults, signs of young deformation, and packages of syntectonic sediments. These pieces of a complex active tectonic puzzle have yielded some answers to longstanding questions such as: How is fault slip transfer in this area accommodated

Ion-solvation structure and battery electrode characteristics of nonflammable organic electrolytes based on tris(trifluoroethyl)phosphate dissolving lithium salts.

PubMed

Todorov, Yanko Marinov; Fujii, Kenta; Yoshimoto, Nobuko; Hirayama, Daisuke; Aoki, Masahiro; Mimura, Hideyuki; Morita, Masayuki

2017-11-29

The structure and properties of lithium salt solutions based on tris(2,2,2-trifluoroethyl)phosphate (TFEP) solvent have been studied to design a safer electrolyte system for large-sized lithium-ion battery applications. Influences of the ionic structure on the polarization behavior of the LiCoO 2 (LCO) positive electrode were investigated. The ionic conductivity and viscosity of the solution consisting of lithium salts dissolved in TFEP, LiX/TFEP (X = PF 6 , BF 4 and TFSA) (TFSA = (CF 3 SO 2 ) 2 N), were measured. The results suggest that the ion-solvation structure greatly depends on the anionic species in the salt. Spectroscopic measurements also support the conclusion that the Li + -solvation structure varies with the lithium salts. The differences in the ionic structure of LiX/TFEP influence the electrochemical oxidation potential of the solution and the polarization behavior of the LCO electrode. The overvoltage for Li-desertion/insertion from/into LCO in LiX/TFEP, being much higher than that observed in conventional LIB electrolyte solutions, shows the order of BF 4 < PF 6 < TFSA. The addition of ethylene carbonate (EC) to LiX/TFEP increases the ionic conductivity, which is probably caused by changes in the Li + -solvation structure in TFEP. The overvoltage for the Li-desertion/insertion of LCO is much lowered by the addition of EC to LiX/TFEP.

Desert bighorn sheep mortality due to presumptive type C botulism in California

USGS Publications Warehouse

Swift, P.K.; Wehausen, J.D.; Ernest, H.B.; Singer, R.S.; Pauli, A.M.; Kinde, H.; Rocke, T.E.; Bleich, V.C.

2000-01-01

During a routine telemetry flight of the Mojave Desert (California, USA) in August 1995, mortality signals were detected from two of 12 radio-collared female desert bighorn sheep (Ovis canadensis) in the vicinity of Old Dad Peak in San Bernardino County (California). A series of field investigations determined that at least 45 bighorn sheep had died near two artificial water catchments (guzzlers), including 13 bighorn sheep which had presumably drowned in a guzzler tank. Samples from water contaminated by decomposing bighorn sheep carcasses and hemolyzed blood from a fresh bighorn sheep carcass were tested for the presence of pesticides, heavy metals, strychnine, blue-green algae, Clostridium botulinum toxin, ethylene glycol, nitrates, nitrites, sodium, and salts. Mouse bioassay and enzyme-linked immunosorbent assay detected type C botulinum toxin in the hemolyzed blood and in fly larvae and pupae. This, coupled with negative results from other analyses, led us to conclude that type C botulinum poisoning was most likely responsible for the mortality of bighorn sheep outside the guzzler tank.

Salt tolerances of some mainland tree species select as through nursery screening.

PubMed

Miah, Md Abdul Quddus

2013-09-15

A study of salt tolerance was carried out on germination, survival and height growth performance of important mesophytic species such as Acacia auriculiformis, Acacia hybrid, Artocarpus heterophyllus, Albizia procera, Albizia lebbeck, Acacia nilotica, Achras sapota, Casuarina equisetifolaia, Emblica officinalis, Leucaena leucocephala, Samania saman, Swetenia macrophylla, Terminalia arjuna, Tamarindus indica, Terminalia bellirica and Thespesia populnea in nursery stage using fresh water and salt (NaCl) solutions of 10, 15 and 20 ppm. Effect of salt on germination, survival performance and height growth performance were examined in this condition. Based on the observation, salt tolerance of these species has been determined Acacia auriculiformis, Acacia hybrid, Achras sapota, Casuarina equisetifolia, Leucaena leucocephala and Tamarindus indica has showed the best capacity to perform in different salinity conditions. Acacia nilotica, Emblica officinalis, Thespesia populnea has performed better. Albizia procera, Samania saman and Terminalia bellirica, germination and height performance showed good but when salinity increases survivability were decreases.

Feasibility of biodiesel production and CO2 emission reduction by Monoraphidium dybowskii LB50 under semi-continuous culture with open raceway ponds in the desert area.

PubMed

Yang, Haijian; He, Qiaoning; Hu, Chunxiang

2018-01-01

Compared with other general energy crops, microalgae are more compatible with desert conditions. In addition, microalgae cultivated in desert regions can be used to develop biodiesel. Therefore, screening oil-rich microalgae, and researching the algae growth, CO 2 fixation and oil yield in desert areas not only effectively utilize the idle desertification lands and other resources, but also reduce CO 2 emission. Monoraphidium dybowskii LB50 can be efficiently cultured in the desert area using light resources, and lipid yield can be effectively improved using two-stage induction and semi-continuous culture modes in open raceway ponds (ORPs). Lipid content (LC) and lipid productivity (LP) were increased by 20% under two-stage industrial salt induction, whereas biomass productivity (BP) increased by 80% to enhance LP under semi-continuous mode in 5 m 2 ORPs. After 3 years of operation, M. dybowskii LB50 was successfully and stably cultivated under semi-continuous mode for a month during five cycles of repeated culture in a 200 m 2 ORP in the desert area. This culture mode reduced the supply of the original species. The BP and CO 2 fixation rate were maintained at 18 and 33 g m -2  day -1 , respectively. Moreover, LC decreased only during the fifth cycle of repeated culture. Evaporation occurred at 0.9-1.8 L m -2  day -1 , which corresponded to 6.5-13% of evaporation loss rate. Semi-continuous and two-stage salt induction culture modes can reduce energy consumption and increase energy balance through the energy consumption analysis of life cycle. This study demonstrates the feasibility of combining biodiesel production and CO 2 fixation using microalgae grown as feedstock under culture modes with ORPs by using the resources in the desert area. The understanding of evaporation loss and the sustainability of semi-continuous culture render this approach practically viable. The novel strategy may be a promising alternative to existing technology for CO 2 emission

Fungal endophytes in aboveground tissues of desert plants: infrequent in culture, but highly diverse and distinctive symbionts.

PubMed

Massimo, Nicholas C; Nandi Devan, M M; Arendt, Kayla R; Wilch, Margaret H; Riddle, Jakob M; Furr, Susan H; Steen, Cole; U'Ren, Jana M; Sandberg, Dustin C; Arnold, A Elizabeth

2015-07-01

In hot deserts, plants cope with aridity, high temperatures, and nutrient-poor soils with morphological and biochemical adaptations that encompass intimate microbial symbioses. Whereas the root microbiomes of arid-land plants have received increasing attention, factors influencing assemblages of symbionts in aboveground tissues have not been evaluated for many woody plants that flourish in desert environments. We evaluated the diversity, host affiliations, and distributions of endophytic fungi associated with photosynthetic tissues of desert trees and shrubs, focusing on nonsucculent woody plants in the species-rich Sonoran Desert. To inform our strength of inference, we evaluated the effects of two different nutrient media, incubation temperatures, and collection seasons on the apparent structure of endophyte assemblages. Analysis of >22,000 tissue segments revealed that endophytes were isolated four times more frequently from photosynthetic stems than leaves. Isolation frequency was lower than expected given the latitude of the study region and varied among species a function of sampling site and abiotic factors. However, endophytes were very species-rich and phylogenetically diverse, consistent with less arid sites of a similar latitudinal position. Community composition differed among host species, but not as a function of tissue type, sampling site, sampling month, or exposure. Estimates of abundance, diversity, and composition were not influenced by isolation medium or incubation temperature. Phylogenetic analyses of the most commonly isolated genus (Preussia) revealed multiple evolutionary origins of desert-plant endophytism and little phylogenetic structure with regard to seasonality, tissue preference, or optimal temperatures and nutrients for growth in vitro. Together, these results provide insight into endophytic symbioses in desert-plant communities and can be used to optimize strategies for capturing endophyte biodiversity at regional scales.

Growth performance of indigenous sheep fed Sporobolus virginicus grass hay grown in saline desert lands and irrigated with high salt content ground water.

PubMed

Alhadrami, G A; Al-Shorepy, S A; Yousef, A M

2010-12-01

Twenty-eight indigenous ewe lambs (6 months of age and 14.4 kg body weight (BW)) were used to evaluate the effect of feeding Sporobolus grass hay (SGH) as the only source of forage on growth, and feed and water intakes. The ewe lambs were randomly and equally allocated to two treatment groups (14 lambs/group). The ewe lambs in group 1 (treatment 1) received SGH, while lambs in group 2 (treatment 2) received Rhodes grass hay (RGH) as the only source of forage. Water was available at all times for both treatment groups. Sporobolus grass was irrigated with brackish water of high salt content (20,000 ppm) and grown in saline desert lands (sabkha) in the United Arab Emirates. The average daily dry matter intake was significantly (P < .05) higher for the animals fed SGH than those fed RGH at all stages. Both water intakes per unit body gain and water intake per unit feed intake were significant (P < .05) between the two treatments group at all stages. Average daily gain did not differ significantly (P > .05) between the two groups at all stages. From these data, we conclude that SGH can replace Rhodes hay in sheep diet without significant effect on sheep performance.

Stable isotope evidence for an atmospheric origin of desert nitrate deposits in northern Chile and southern California, U.S.A.

USGS Publications Warehouse

Böhlke, J.K.; Ericksen, G.E.; Revesz, K.

1997-01-01

Natural surficial accumulations of nitrate-rich salts in the Atacama Desert, northern Chile, and in the Death Valley region of the Mojave Desert, southern California, are well known, but despite many geologic and geochemical studies, the origins of the nitrates have remained controversial. N and O isotopes in nitrate, and S isotopes in coexisting soluble sulfate, were measured to determine if some proposed N sources could be supported or rejected, and to determine if the isotopic signature of these natural deposits could be used to distinguish them from various types of anthropogenic nitrate contamination that might be found in desert groundwaters. High-grade caliche-type nitrate deposits from both localities have ??15N values that range from -5 to +5???, but are mostly near 0???. Values of ??15N near 0??? are consistent with either bulk atmospheric N deposition or microbial N fixation as major sources of the N in the deposits. ??18O values of those desert nitrates with ??15N near 0??? range from about +31 to + 50??? (V-SMOW), significantly higher than that of atmospheric O2 (+ 23.5???). Such high values of ??18O are considered unlikely to result entirely from nitrification of reduced N, but rather resemble those of modern atmospheric nitrate in precipitation from some other localities. Assuming that limited modern atmospheric isotope data are applicable to the deposits, and allowing for nitrification of co-deposited ammonium, it is estimated that the fraction of the nitrate in the deposits that could be accounted for isotopically by atmospheric N deposition may be at least 20% and possibly as much as 100%. ??34S values are less diagnostic but could also be consistent with atmospheric components in some of the soluble sulfates associated with the deposits. The stable isotope data support the hypothesis that some high-grade caliche-type nitrate-rich salt deposits in some of the Earth's hyperarid deserts represent long-term accumulations of atmospheric deposition

Namib Desert edaphic bacterial, fungal and archaeal communities assemble through deterministic processes but are influenced by different abiotic parameters.

PubMed

Johnson, Riegardt M; Ramond, Jean-Baptiste; Gunnigle, Eoin; Seely, Mary; Cowan, Don A

2017-03-01

The central Namib Desert is hyperarid, where limited plant growth ensures that biogeochemical processes are largely driven by microbial populations. Recent research has shown that niche partitioning is critically involved in the assembly of Namib Desert edaphic communities. However, these studies have mainly focussed on the Domain Bacteria. Using microbial community fingerprinting, we compared the assembly of the bacterial, fungal and archaeal populations of microbial communities across nine soil niches from four Namib Desert soil habitats (riverbed, dune, gravel plain and salt pan). Permutational multivariate analysis of variance indicated that the nine soil niches presented significantly different physicochemistries (R 2  = 0.8306, P ≤ 0.0001) and that bacterial, fungal and archaeal populations were soil niche specific (R 2  ≥ 0.64, P ≤ 0.001). However, the abiotic drivers of community structure were Domain-specific (P < 0.05), with P, clay and sand fraction, and NH 4 influencing bacterial, fungal and archaeal communities, respectively. Soil physicochemistry and soil niche explained over 50% of the variation in community structure, and communities displayed strong non-random patterns of co-occurrence. Taken together, these results demonstrate that in central Namib Desert soil microbial communities, assembly is principally driven by deterministic processes.

Practical salinity management for leachate irrigation to poplar trees.

PubMed

Smesrud, Jason K; Duvendack, George D; Obereiner, James M; Jordahl, James L; Madison, Mark F

2012-01-01

Landfill leachate can be beneficially reused for irrigation of fiber crops with appropriate attention to nutrient and salinity management. The Riverbend Landfill in Western Oregon has been effectively practicing irrigation of landfill leachate to poplar trees since 1993. Over that time, the site has been adaptively managed to control salinity impacts to the tree crop while beneficially utilizing the applied water and nutrients during each growing season. Representative leachate irrigation water has ranged in concentration of total dissolved solids from 777 to 6,940 mg/L, chloride from 180 to 1,760 mg/L and boron from 3.2 to 7.3 mg/L. Annual leachate irrigation applications have also ranged between 102 and 812 mm/yr. Important conclusions from this site have included: 1) Appropriate tree clone selection and tree stand spacing, thinning, and harvest rotations are critical to maintaining a productive tree stand that is resilient and resistant to salt stress. The most effective combinations have included clones DN-34, OP-367, 184-411, 49-177, and 15-29 planted at spacing of 3.7-m x 1.8-m to 3.7-m x 3.7-m; 2) Leaf tissue boron levels are closely correlated to soil boron levels and can be managed with leaching. When leaf tissue boron levels exceed 200 to 250 mg/kg, signs of salt stress may emerge and should be monitored closely; 3) Salinity from leachate irrigation can be managed to sustain a healthy tree crop by controlling mass loading rates and providing appropriate irrigation blending if necessary. Providing freshwater irrigation following each leachate irrigation and targeting freshwater irrigation as 30 percent of total irrigation water applied has successfully controlled salt impacts to vegetation; and 4) Drip irrigation generally requires more careful attention to long-term soil salinity management than spray irrigation. Moving drip irrigation tubes periodically to prevent the formation of highly saline zones within the soil profile is important. In this paper, a

Transgenic Overexpression of Abcb11 Enhances Biliary Bile Salt Outputs, But Does Not Affect Cholesterol Cholelithogenesis in Mice

PubMed Central

Wang, Helen H.; Lammert, Frank; Schmitz, Anne; Wang, David Q.-H.

2010-01-01

Background Cholesterol gallstone disease is a complex genetic trait and induced by multiple but as yet unknown genes. A major Lith gene, Lith1 was first identified on chromosome 2 in gallstone-susceptible C57L mice compared with resistant AKR mice. Abcb11, encoding the canalicular bile salt export pump in the hepatocyte, co-localizes with the Lith1 QTL region and its hepatic expression is significantly higher in C57L mice than in AKR mice. Material and methods To investigate whether Abcb11 influences cholesterol gallstone formation, we created an Abcb11 transgenic strain on the AKR genetic background and fed these mice with a lithogenic diet for 56 days. Result We excluded functionally relevant polymorphisms of the Abcb11 gene and its promoter region between C57L and AKR mice. Overexpression of Abcb11 significantly promoted biliary bile salt secretion and increased circulating bile salt pool size and bile salt-dependent bile flow rate. However, biliary cholesterol and phospholipid secretion, as well as gallbladder size and contractility were comparable in transgenic and wild-type mice. At 56 days on the lithogenic diet, cholesterol saturation indexes of gallbladder biles and gallstone prevalence rates were essentially similar in these two groups of mice. Conclusion Overexpression of Abcb11 augments biliary bile salt secretion, but does not affect cholelithogenesis in mice. PMID:20456485

Sugary secretions of wasp galls: a want-to-be extrafloral nectar?

PubMed

Aranda-Rickert, Adriana; Rothen, Carolina; Diez, Patricia; González, Ana María; Marazzi, Brigitte

2017-11-10

The most widespread form of protective mutualisms is represented by plants bearing extrafloral nectaries (EFNs) that attract ants and other arthropods for indirect defence. Another, but less common, form of sugary secretion for indirect defence occurs in galls induced by cynipid wasps. Until now, such galls have been reported only for cynipid wasps that infest oak trees in the northern hemisphere. This study provides the first evidence of galls that exude sugary secretions in the southern hemisphere and asks whether they can be considered as analogues of plants' EFNs. The ecology and anatomy of galls and the chemical composition of the secretion were investigated in north-western Argentina, in natural populations of the host trees Prosopis chilensis and P. flexuosa . To examine whether ants protect the galls from natural enemies, ant exclusion experiments were conducted in the field. The galls produce large amounts of sucrose-rich, nectar-like secretions. No typical nectary and sub-nectary parenchymatic tissues or secretory trichomes can be observed; instead there is a dense vascularization with phloem elements reaching the gall periphery. At least six species of ants, but also vespid wasps, Diptera and Coleoptera, consumed the gall secretions. The ant exclusion experiment showed that when ants tended galls, no differences were found in the rate of successful emergence of gall wasps or in the rate of parasitism and inquiline infestation compared with ant-excluded galls. The gall sugary secretion is not analogous to extrafloral nectar because no nectar-producing structure is associated with it, but is functionally equivalent to arthropod honeydew because it provides indirect defence to the plant parasite. As in other facultative mutualisms mediated by sugary secretions, the gall secretion triggers a complex multispecies interaction, in which the outcome of individual pair-wise interactions depends on the ecological context in which they take place. © The Author

Anastatica hierochuntica, an Arabidopsis Desert Relative, Is Tolerant to Multiple Abiotic Stresses and Exhibits Species-Specific and Common Stress Tolerance Strategies with Its Halophytic Relative, Eutrema (Thellungiella) salsugineum

PubMed Central

Eshel, Gil; Shaked, Ruth; Kazachkova, Yana; Khan, Asif; Eppel, Amir; Cisneros, Aroldo; Acuna, Tania; Gutterman, Yitzhak; Tel-Zur, Noemi; Rachmilevitch, Shimon; Fait, Aaron; Barak, Simon

2017-01-01

The search for novel stress tolerance determinants has led to increasing interest in plants native to extreme environments – so called “extremophytes.” One successful strategy has been comparative studies between Arabidopsis thaliana and extremophyte Brassicaceae relatives such as the halophyte Eutrema salsugineum located in areas including cold, salty coastal regions of China. Here, we investigate stress tolerance in the desert species, Anastatica hierochuntica (True Rose of Jericho), a member of the poorly investigated lineage III Brassicaceae. We show that A. hierochuntica has a genome approximately 4.5-fold larger than Arabidopsis, divided into 22 diploid chromosomes, and demonstrate that A. hierochuntica exhibits tolerance to heat, low N and salt stresses that are characteristic of its habitat. Taking salt tolerance as a case study, we show that A. hierochuntica shares common salt tolerance mechanisms with E. salsugineum such as tight control of shoot Na+ accumulation and resilient photochemistry features. Furthermore, metabolic profiling of E. salsugineum and A. hierochuntica shoots demonstrates that the extremophytes exhibit both species-specific and common metabolic strategies to cope with salt stress including constitutive up-regulation (under control and salt stress conditions) of ascorbate and dehydroascorbate, two metabolites involved in ROS scavenging. Accordingly, A. hierochuntica displays tolerance to methyl viologen-induced oxidative stress suggesting that a highly active antioxidant system is essential to cope with multiple abiotic stresses. We suggest that A. hierochuntica presents an excellent extremophyte Arabidopsis relative model system for understanding plant survival in harsh desert conditions. PMID:28144244

Water Relations and Foliar Isotopic Composition of Prosopis tamarugo Phil., an Endemic Tree of the Atacama Desert Growing at Three Levels of Water Table Depth.

PubMed

Garrido, Marco; Silva, Paola; Acevedo, Edmundo

2016-01-01

Prosopis tamarugo Phil. is a strict phreatophyte tree species endemic to the "Pampa del Tamarugal", Atacama Desert. The extraction of water for various uses has increased the depth of the water table in the Pampa aquifers threatening its conservation. This study aimed to determine the effect of the groundwater table depth on the water relations of P. tamarugo and to present thresholds of groundwater depth (GWD) that can be used in the groundwater management of the P. tamarugo ecosystem. Three levels of GWD, 11.2 ± 0.3 m, 10.3 ± 0.3 m, and 7.1 ± 0.1 m, (the last GWD being our reference) were selected and groups of four individuals per GWD were studied in the months of January and July of the years 2011 through 2014. When the water table depth exceeded 10 m, P. tamarugo had lower pre-dawn and mid-day water potential but no differences were observed in minimum leaf stomatal resistance when compared to the condition of 7.1 m GWD; the leaf tissue increased its δ(13)C and δ(18)O composition. Furthermore, a smaller green canopy fraction of the trees and increased foliage loss in winter with increasing water table depth was observed. The differences observed in the physiological behavior of P. tamarugo trees, attributable to the ground water depth; show that increasing the depth of the water table from 7 to 11 m significantly affects the water status of P. tamarugo. The results indicate that P. tamarugo has an anisohydric stomatal behavior and that given a reduction in water supply it regulates the water demand via foliage loss. The growth and leaf physiological activities are highly sensitive to GWD. The foliage loss appears to prevent the trees from reaching water potentials leading to complete loss of hydraulic functionality by cavitation. The balance achieved between water supply and demand was reflected in the low variation of the water potential and of the variables related to gas exchange over time for a given GWD. This acclimation capacity of P. tamarugo after

Water Relations and Foliar Isotopic Composition of Prosopis tamarugo Phil., an Endemic Tree of the Atacama Desert Growing at Three Levels of Water Table Depth

PubMed Central

Garrido, Marco; Silva, Paola; Acevedo, Edmundo

2016-01-01

Prosopis tamarugo Phil. is a strict phreatophyte tree species endemic to the “Pampa del Tamarugal”, Atacama Desert. The extraction of water for various uses has increased the depth of the water table in the Pampa aquifers threatening its conservation. This study aimed to determine the effect of the groundwater table depth on the water relations of P. tamarugo and to present thresholds of groundwater depth (GWD) that can be used in the groundwater management of the P. tamarugo ecosystem. Three levels of GWD, 11.2 ± 0.3 m, 10.3 ± 0.3 m, and 7.1 ± 0.1 m, (the last GWD being our reference) were selected and groups of four individuals per GWD were studied in the months of January and July of the years 2011 through 2014. When the water table depth exceeded 10 m, P. tamarugo had lower pre-dawn and mid-day water potential but no differences were observed in minimum leaf stomatal resistance when compared to the condition of 7.1 m GWD; the leaf tissue increased its δ13C and δ18O composition. Furthermore, a smaller green canopy fraction of the trees and increased foliage loss in winter with increasing water table depth was observed. The differences observed in the physiological behavior of P. tamarugo trees, attributable to the ground water depth; show that increasing the depth of the water table from 7 to 11 m significantly affects the water status of P. tamarugo. The results indicate that P. tamarugo has an anisohydric stomatal behavior and that given a reduction in water supply it regulates the water demand via foliage loss. The growth and leaf physiological activities are highly sensitive to GWD. The foliage loss appears to prevent the trees from reaching water potentials leading to complete loss of hydraulic functionality by cavitation. The balance achieved between water supply and demand was reflected in the low variation of the water potential and of the variables related to gas exchange over time for a given GWD. This acclimation capacity of P. tamarugo after

Practical water production from desert air

PubMed Central

Kalmutzki, Markus J.; Kapustin, Eugene A.

2018-01-01

Energy-efficient production of water from desert air has not been developed. A proof-of-concept device for harvesting water at low relative humidity was reported; however, it used external cooling and was not desert-tested. We report a laboratory-to-desert experiment where a prototype using up to 1.2 kg of metal-organic framework (MOF)–801 was tested in the laboratory and later in the desert of Arizona, USA. It produced 100 g of water per kilogram of MOF-801 per day-and-night cycle, using only natural cooling and ambient sunlight as a source of energy. We also report an aluminum-based MOF-303, which delivers more than twice the amount of water. The desert experiment uncovered key parameters pertaining to the energy, material, and air requirements for efficient production of water from desert air, even at a subzero dew point. PMID:29888332

Practical water production from desert air.

PubMed

Fathieh, Farhad; Kalmutzki, Markus J; Kapustin, Eugene A; Waller, Peter J; Yang, Jingjing; Yaghi, Omar M

2018-06-01

Energy-efficient production of water from desert air has not been developed. A proof-of-concept device for harvesting water at low relative humidity was reported; however, it used external cooling and was not desert-tested. We report a laboratory-to-desert experiment where a prototype using up to 1.2 kg of metal-organic framework (MOF)-801 was tested in the laboratory and later in the desert of Arizona, USA. It produced 100 g of water per kilogram of MOF-801 per day-and-night cycle, using only natural cooling and ambient sunlight as a source of energy. We also report an aluminum-based MOF-303, which delivers more than twice the amount of water. The desert experiment uncovered key parameters pertaining to the energy, material, and air requirements for efficient production of water from desert air, even at a subzero dew point.

Bacterial Diversity in Microbial Mats and Sediments from the Atacama Desert.

PubMed

Rasuk, Maria Cecilia; Fernández, Ana Beatriz; Kurth, Daniel; Contreras, Manuel; Novoa, Fernando; Poiré, Daniel; Farías, María Eugenia

2016-01-01

The Atacama Desert has extreme environmental conditions that allow the development of unique microbial communities. The present paper reports the bacterial diversity of microbial mats and sediments and its mineralogical components. Some physicochemical conditions of the water surrounding these ecosystems have also been studied trying to determine their influence on the diversity of these communities. In that way, mats and sediments distributed among different hypersaline lakes located in salt flats of the Atacama Desert were subjected to massive parallel sequencing of the V4 region of the 16S rRNA genes of Bacteria. A higher diversity in sediment than in mat samples have been found. Lakes that harbor microbial mats have higher salinity than lakes where mats are absent. Proteobacteria and/or Bacteroidetes are the major phyla represented in all samples. An interesting item is the finding of a low proportion or absence of Cyanobacteria sequences in the ecosystems studied, suggesting the possibility that other groups may be playing an essential role as primary producers in these extreme environments. Additionally, the large proportion of 16S rRNA gene sequences that could not be classified at the level of phylum indicates potential new phyla present in these ecosystems.

Body wiping behaviors associated with cutaneous lipids in hylid tree frogs of Florida.

PubMed

Barbeau, Tamatha R; Lillywhite, Harvey B

2005-06-01

Body wiping behavior, integumentary secretions and rates of evaporative water loss (EWL) were examined in six species of Florida tree frogs (Anura: Hylidae). Additionally, morphology of the integument and dermal glands were compared among these and one other Florida tree frog (Hyla andersonii), an arid-adapted tree frog (Phyllomedusa hypochondrialis), and a highly aquatic frog (Rana utricularia). An extra-epidermal layer of lipid and mucus, presumably secreted from dermal granular glands, was detected on the skin of all Florida hylid frogs examined. Distinct body wiping behaviors were observed in the hylid frogs, but these were less complex than those described previously in phyllomedusine frogs, which occupy arid habitats, secrete lipids onto their skin, and are regarded as relatively 'waterproof'. Florida hylids occupy seasonally arid habitats and appear to have reduced rates of EWL. The suite of traits we observed in these frogs have been previously documented in a rhacophorid tree frog from seasonally arid regions of India and likely represent an evolutionary convergent response to periodic dehydration stress. The presence of lipids that are spread by simple wiping behaviors to form an extra-epidermal water barrier may represent an early stage of the more advanced adaptations described in more waterproof arboreal frogs.

Gopherus agassizii: Desert tortoise

USGS Publications Warehouse

Berry, Kristen H.; Swingland, Ian Richard; Klemens, Michael W.

1989-01-01

The desert tortoise is one of four allopatric North American tortoises. It occurs in the Mojave and Sonoran deserts of the southwestern United States and Mexico.Auffenberg (1976) divided the genus Gopherus (consisting of four species, G. agassizi, G. berlandieri, G.flavomarginatus, and G. polyphemus) in two osteological groups. Bramble (1982), using morphological and palaeontological data, divided the genus Gopherus into two separate complexes, each with two species. He established a new genus, Scaptochelys, for agassizi and berlandieri, retaining Gopherus for polyphemus and flavomarginatus. Bour and Dubois (1984) noted that Xerobates Agassiz had priority over Scaptochelys Bramble. Using mitochondrial DNA (mtDNA), Lamb et al. (1989) evaluated the evolutionary relationships of the North American tortoises, particularly the desert tortoise. They concluded that the mtDNA analysis provides strong support for generic recognition of the two distinct species groups described by Bramble (1982).Until a few decades ago, the desert tortoise was widespread at lower elevations throughout the Mojave and Sonoran deserts of the U.S.A. In the northern and western parts of the geographic range, large and relatively homogeneous populations with densities exceeding 1,000/sq km extended throughout parts of California, and probably into Nevada and Utah. In terms of biomass, the tortoise played an important role in the ecosystems. In most areas, numbers have declined dramatically and the extent of populations has been reduced. Most populations are now isolated and low in numbers. Conservation of the desert tortoise is a highly visible and political issue in the U.S.A., but not in Mexico.

Jeeps Penetrating a Hostile Desert

ERIC Educational Resources Information Center

Bailey, Herb

2009-01-01

Several jeeps are poised at base camp on the edge of a desert aiming to escort one of them as far as possible into the desert, while the others return to camp. They all have full tanks of gas and share their fuel to maximize penetration. In a friendly desert it is best to leave caches of fuel along the way to help returning jeeps. We solve the…

Little Ice Age Wetting of Interior Asian Deserts and the Rise of the Mongol Empire

NASA Astrophysics Data System (ADS)

Putnam, A. E.; Putnam, D.; Andreu-Hayles, L.; Cook, E. R.; Palmer, J. G.; Clark, E. H.; WANG, C.; Chen, F.; Denton, G.; Boyle, D. P.; Bassett, S.; Birkel, S. D.; Martin Fernandez, J.; Hajdas, I.; Southon, J. R.; Garner, C.; Broecker, W. S.

2015-12-01

Documenting hydrological responses to past climate changes may provide insights into how ongoing warming will alter the distribution of Earth's water resources. Here we report evidence suggesting that wetter-than-present conditions persisted during the past millennium in the deserts of the Tarim Basin, western China, located at the heart of Asia - Earth's largest and most populous continent. Our assessment is based on observations of landforms composed of waterlain sediments occurring throughout the Taklamakan and Lop Deserts of the Tarim Basin. These landforms are associated with subfossil phreatophyte trees, reeds, and mollusk shells. We applied 14C and dendrochronological dating techniques to construct a chronology for when the Tarim Basin was wetter than today. We also employed hydrological modeling to estimate plausible climatic conditions under which the observed wet environment could have been sustained. Our results indicate that the core of the Asian desert belt was dominantly wetter than today during the last major cold spell of the Holocene: The Little Ice Age. Wetter conditions in the Tarim Basin deserts accompanied northern cooling, snowline lowering, a strengthened boreal jet, and coeval weakening of south Asian monsoons. Southward migration of grasslands in response to wetter conditions may have aided the spread of the Mongol Empire across Asian drylands. On the other hand, net drying over the 20th century has led to drought that is unprecedented for at least the past ~830 years, and which could intensify with further warming.

Impacts of water and nitrogen addition on nitrogen recovery in Haloxylon ammodendron dominated desert ecosystems.

PubMed

Cui, Xiaoqing; Yue, Ping; Gong, Yanming; Li, Kaihui; Tan, Dunyan; Goulding, Keith; Liu, Xuejun

2017-12-01

Desert ecosystems are likely to change in response to global climate change and nitrogen (N) deposition. The effects of increased precipitation and N deposition on plant growth and the N cycle largely depend on N allocation and N recovery efficiency in the plant-soil ecosystem, but there is limited research on this in desert ecosystems. Here we report results using double-labeled 15 NH 4 15 NO 3 (30 and 60kgNha -1 yr -1 ) as a tracer under ambient (no additional water addition) and enhanced precipitation (60mm water addition) in a Haloxylon ammodendron dominated ecosystem in the Gurbantunggut Desert of Northwest China. Herbaceous plants were a significantly larger sink for added 15 N than the H. ammodendron trees, and N retention varied with water and N addition, relative to growing season precipitation. The retention of added 15 N varied within the components of H. ammodendron, with the stems retaining most, followed by the assimilation branches. Soil was the dominant sink for added 15 N, in which the topsoil and subsoil respond differently to water and N addition over the two-year period. Nitrogen relative recovery percentage in the whole ecosystem ranged from 43% to 61%, lower than average recovery rate in temperate forests; N tracer recovery percentage significantly increased with water addition but decreased with enhanced N deposition. Future N cycling in central Asian deserts will depend on changes in precipitation. Copyright © 2017 Elsevier B.V. All rights reserved.

Nitrogen nutrition of poplar trees.

PubMed

Rennenberg, H; Wildhagen, H; Ehlting, B

2010-03-01

Many forest ecosystems have evolved at sites with growth-limiting nitrogen (N) availability, low N input from external sources and high ecosystem internal cycling of N. By contrast, many poplar species are frequent constituents of floodplain forests where they are exposed to a significant ecosystem external supply of N, mainly nitrate, in the moving water table. Therefore, nitrate is much more important for N nutrition of these poplar species than for many other tree species. We summarise current knowledge of nitrate uptake and its regulation by tree internal signals, as well as acquisition of ammonium and organic N from the soil. Unlike herbaceous plants, N nutrition of trees is sustained by seasonal, tree internal cycling. Recent advances in the understanding of seasonal storage and mobilisation in poplar bark and regulation of these processes by temperature and daylength are addressed. To explore consequences of global climate change on N nutrition of poplar trees, responses of N uptake and metabolism to increased atmospheric CO(2) and O(3) concentrations, increased air and soil temperatures, drought and salt stress are highlighted.

Cadmium hampers salt tolerance of Sesuvium portulacastrum.

PubMed

Wali, Mariem; Martos, Soledad; Pérez-Martín, Laura; Abdelly, Chedly; Ghnaya, Tahar; Poschenrieder, Charlotte; Gunsé, Benet

2017-06-01

It is well known that salinity reduces cadmium toxicity in halophytes. However, the possible interference of Cd with the mechanisms of salt tolerance is poorly explored. The aim of this study was to see whether Cd affects salt tolerance mechanisms in the halophyte Sesuvium portulacastrum. S. portulacastrum plants obtained from cuttings were grown in hydroponics for 3 weeks and then exposed to low (0.09 mM) or moderate (200 mM) NaCl concentrations, alone or in combination with 25 μM CdCl 2 . Microscopy observation revealed two strategies of salt tolerance: euhalophytism and secretion of salt by bladder cells. Cadmium exposure hardly influenced the total leaf Na + concentrations. However, Cd supply delayed the salt-induced upregulation of AHA1 (plasma membrane H + -ATPase 1) and SOS1 (plasma membrane Na + transporter "Salt Overly Sensitive 1"), genes that are essential for salt tolerance. Moreover, Cd induced the activation of BADH, coding for betaine aldehyde dehydrogenase, indicating enhanced osmotic stress due to Cd. Sodium-green fluorescence in protoplasts from plants grown with low or high NaCl, alone or in combination with Cd, revealed higher Na + concentrations in the cytoplasm of Cd-exposed plants. Taken together the results indicate interference of Cd with salt tolerance mechanisms in S. portulacastrum. This may have consequences for the efficient use of halophytes in phytoremediation of Cd-contaminated saline soils. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Salt excretion in Suaeda fruticosa.

PubMed

Labidi, Nehla; Ammari, Manel; Mssedi, Dorsaf; Benzerti, Maali; Snoussi, Sana; Abdelly, C

2010-09-01

Suaeda fruticosa is a perennial "includer" halophyte devoid of glands or trichomes with a strong ability of accumulating and sequestrating Na(+) and Cl(-). We were interested in determining whether leaf cuticle salt excretion could be involved as a further mechanism in salt response of this species after long-term treatment with high salinity levels. Seedlings had been treated for three months with seawater (SW) diluted with tap water (0, 25, 50 and 75% SW). Leaf scanning electron microscopy revealed a convex adaxial side sculpture and a higher accumulation of saline crystals at the lamina margin, with a large variability on repartition and size between treatments. No salt gland or salt bladder was found. Threedimensional wax decorations were the only structures found on leaf surface. Washing the leaf surface with water indicated that sodium and chloride predominated in excreted salts, and that potassium was poorly represented. Optimal growth of whole plant was recorded at 25% SW, correlating with maximum Na(+) and Cl(-) absolute secretion rate. The leaves of plants treated with SW retained more water than those of plants treated with tap water due to lower solute potential, especially at 25% SW. Analysis of compatible solute, such as proline, total soluble carbohydrates and glycinebetaine disclosed strong relationship between glycinebetaine and osmotic potential (r = 0.92) suggesting that tissue hydration was partly maintained by glycinebetaine accumulation. Thus in S. fruticosa , increased solute accumulation associated with water retention, and steady intracellular ion homeostasis confirms the "includer" strategy of salt tolerance previously demonstrated. However, salt excretion at leaf surface also participated in conferring to this species a capacity in high salinity tolerance.

Fungal endophytes in above-ground tissues of desert plants: infrequent in culture, but highly diverse and distinctive symbionts

PubMed Central

Massimo, Nicholas C.; Nandi Devan, MM; Arendt, Kayla R.; Wilch, Margaret H.; Riddle, Jakob M.; Furr, Susan H.; Steen, Cole; U'Ren, Jana M.; Sandberg, Dustin C.; Arnold, A. Elizabeth

2015-01-01

In hot deserts, plants cope with aridity, high temperatures, and nutrient-poor soils with morphological and biochemical adaptations that encompass intimate microbial symbioses. Whereas the root microbiomes of arid-land plants have received increasing attention, factors influencing assemblages of symbionts in above-ground tissues have not been evaluated for many woody plants that flourish in desert environments. We evaluated the diversity, host affiliations, and distributions of endophytic fungi associated with photosynthetic tissues of desert trees and shrubs, focusing on non-succulent woody plants in the species-rich Sonoran Desert. To inform our strength of inference, we evaluated the effects of two different nutrient media, incubation temperatures, and collection seasons on the apparent structure of endophyte assemblages. Analysis of >22,000 tissue segments revealed that endophytes were isolated four times more frequently from photosynthetic stems than leaves. Isolation frequency was lower than expected given the latitude of the study region, and varied among species a function of sampling site and abiotic factors. However, endophytes were very species-rich and phylogenetically diverse, consistent with less-arid sites of a similar latitudinal position. Community composition differed among host species, but not as a function of tissue type, sampling site, sampling month, or exposure. Estimates of abundance, diversity and composition were not influenced by isolation medium or incubation temperature. Phylogenetic analyses of the most commonly isolated genus (Preussia) revealed multiple evolutionary origins of desert-plant endophytism and little phylogenetic structure with regard to seasonality, tissue preference, or optimal temperatures and nutrients for growth in vitro. Together, these results provide insight into endophytic symbioses in desert plant communities, and can be used to optimize strategies for capturing endophyte biodiversity at regional scales. PMID

Salt stress induces differential regulation of the phenylpropanoid pathway in Olea europaea cultivars Frantoio (salt-tolerant) and Leccino (salt-sensitive).

PubMed

Rossi, Lorenzo; Borghi, Monica; Francini, Alessandra; Lin, Xiuli; Xie, De-Yu; Sebastiani, Luca

2016-10-01

Olive tree (Olea europaea L.) is an important crop in the Mediterranean Basin where drought and salinity are two of the main factors affecting plant productivity. Despite several studies have reported different responses of various olive tree cultivars to salt stress, the mechanisms that convey tolerance and sensitivity remain largely unknown. To investigate this issue, potted olive plants of Leccino (salt-sensitive) and Frantoio (salt-tolerant) cultivars were grown in a phytotron chamber and treated with 0, 60 and 120mM NaCl. After forty days of treatment, growth analysis was performed and the concentration of sodium in root, stem and leaves was measured by atomic absorption spectroscopy. Phenolic compounds were extracted using methanol, hydrolyzed with butanol-HCl, and quercetin and kaempferol quantified via high performance liquid-chromatography-electrospray-mass spectrometry (HPLC-ESI-MS) and HPLC-q-Time of Flight-MS analyses. In addition, the transcripts levels of five key genes of the phenylpropanoid pathway were measured by quantitative Real-Time PCR. The results of this study corroborate the previous observations, which showed that Frantoio and Leccino differ in allocating sodium in root and leaves. This study also revealed that phenolic compounds remain stable or are strongly depleted under long-time treatment with sodium in Leccino, despite a strong up-regulation of key genes of the phenylpropanoid pathway was observed. Frantoio instead, showed a less intense up-regulation of the phenylpropanoid genes but overall higher content of phenolic compounds. These data suggest that Frantoio copes with the toxicity imposed by elevated sodium not only with mechanisms of Na + exclusion, but also promptly allocating effective and adequate antioxidant compounds to more sensitive organs. Copyright © 2016 Elsevier GmbH. All rights reserved.

Joshua tree (Yucca brevifolia) seeds are dispersed by seed-caching rodents

USGS Publications Warehouse

Vander Wall, S.B.; Esque, T.; Haines, D.; Garnett, M.; Waitman, B.A.

2006-01-01

Joshua tree (Yucca brevifolia) is a distinctive and charismatic plant of the Mojave Desert. Although floral biology and seed production of Joshua tree and other yuccas are well understood, the fate of Joshua tree seeds has never been studied. We tested the hypothesis that Joshua tree seeds are dispersed by seed-caching rodents. We radioactively labelled Joshua tree seeds and followed their fates at five source plants in Potosi Wash, Clark County, Nevada, USA. Rodents made a mean of 30.6 caches, usually within 30 m of the base of source plants. Caches contained a mean of 5.2 seeds buried 3-30 nun deep. A variety of rodent species appears to have prepared the caches. Three of the 836 Joshua tree seeds (0.4%) cached germinated the following spring. Seed germination using rodent exclosures was nearly 15%. More than 82% of seeds in open plots were removed by granivores, and neither microsite nor supplemental water significantly affected germination. Joshua tree produces seeds in indehiscent pods or capsules, which rodents dismantle to harvest seeds. Because there is no other known means of seed dispersal, it is possible that the Joshua tree-rodent seed dispersal interaction is an obligate mutualism for the plant.

Red tree vole / Arborimus longicaudus.

Treesearch

A.B. Carey

1999-01-01

The secretive nocturnal red tree vole is one of least studied and most specialized voles in North America. It is found only along the coast and in the Western Cascades of Oregon where it spends most of its life in the tops of tall conifers. eating needles of Douglas-fir (Pseudotsuga menziesii) and. Occasionally, other conifers. The voles clip small...

Mojave Desert Ecosystem Program

Science.gov Websites

Toggle navigation logo garis Home About Search Contact About Us History The Mojave Desert Ecosystem providing dynamic, sustainable, land management decision-making at the ecosystem level. Its numerous mission of the Mojave Desert Ecosystem Program is to provide government agencies throughout the Mojave

Deconjugated Bile Salts Produced by Extracellular Bile-Salt Hydrolase-Like Activities from the Probiotic Lactobacillus johnsonii La1 Inhibit Giardia duodenalis In vitro Growth.

PubMed

Travers, Marie-Agnès; Sow, Cissé; Zirah, Séverine; Deregnaucourt, Christiane; Chaouch, Soraya; Queiroz, Rayner M L; Charneau, Sébastien; Allain, Thibault; Florent, Isabelle; Grellier, Philippe

2016-01-01

Giardiasis, currently considered a neglected disease, is caused by the intestinal protozoan parasite Giardia duodenalis and is widely spread in human as well as domestic and wild animals. The lack of appropriate medications and the spread of resistant parasite strains urgently call for the development of novel therapeutic strategies. Host microbiota or certain probiotic strains have the capacity to provide some protection against giardiasis. By combining biological and biochemical approaches, we have been able to decipher a molecular mechanism used by the probiotic strain Lactobacillus johnsonii La1 to prevent Giardia growth in vitro . We provide evidence that the supernatant of this strain contains active principle(s) not directly toxic to Giardia but able to convert non-toxic components of bile into components highly toxic to Giardia . By using bile acid profiling, these components were identified as deconjugated bile-salts. A bacterial bile-salt-hydrolase of commercial origin was able to mimic the properties of the supernatant. Mass spectrometric analysis of the bacterial supernatant identified two of the three bile-salt-hydrolases encoded in the genome of this probiotic strain. These observations document a possible mechanism by which L. johnsonii La1, by secreting, or releasing BSH-like activity(ies) in the vicinity of replicating Giardia in an environment where bile is present and abundant, can fight this parasite. This discovery has both fundamental and applied outcomes to fight giardiasis, based on local delivery of deconjugated bile salts, enzyme deconjugation of bile components, or natural or recombinant probiotic strains that secrete or release such deconjugating activities in a compartment where both bile salts and Giardia are present.

Deconjugated Bile Salts Produced by Extracellular Bile-Salt Hydrolase-Like Activities from the Probiotic Lactobacillus johnsonii La1 Inhibit Giardia duodenalis In vitro Growth

PubMed Central

Travers, Marie-Agnès; Sow, Cissé; Zirah, Séverine; Deregnaucourt, Christiane; Chaouch, Soraya; Queiroz, Rayner M. L.; Charneau, Sébastien; Allain, Thibault; Florent, Isabelle; Grellier, Philippe

2016-01-01

Giardiasis, currently considered a neglected disease, is caused by the intestinal protozoan parasite Giardia duodenalis and is widely spread in human as well as domestic and wild animals. The lack of appropriate medications and the spread of resistant parasite strains urgently call for the development of novel therapeutic strategies. Host microbiota or certain probiotic strains have the capacity to provide some protection against giardiasis. By combining biological and biochemical approaches, we have been able to decipher a molecular mechanism used by the probiotic strain Lactobacillus johnsonii La1 to prevent Giardia growth in vitro. We provide evidence that the supernatant of this strain contains active principle(s) not directly toxic to Giardia but able to convert non-toxic components of bile into components highly toxic to Giardia. By using bile acid profiling, these components were identified as deconjugated bile-salts. A bacterial bile-salt-hydrolase of commercial origin was able to mimic the properties of the supernatant. Mass spectrometric analysis of the bacterial supernatant identified two of the three bile-salt-hydrolases encoded in the genome of this probiotic strain. These observations document a possible mechanism by which L. johnsonii La1, by secreting, or releasing BSH-like activity(ies) in the vicinity of replicating Giardia in an environment where bile is present and abundant, can fight this parasite. This discovery has both fundamental and applied outcomes to fight giardiasis, based on local delivery of deconjugated bile salts, enzyme deconjugation of bile components, or natural or recombinant probiotic strains that secrete or release such deconjugating activities in a compartment where both bile salts and Giardia are present. PMID:27729900

Element uptake, accumulation, and resorption in leaves of mangrove species with different mechanisms of salt regulation

Treesearch

E. Medina; W. Fernandez; F. Barboza

2015-01-01

Element uptake from substrate and resorption capacity of nutrients before leaf shedding are frequently species-specific and difficult to determine in natural settings. We sampled populations of Rhizophora mangle (salt-excluding species) and Laguncularia racemosa (salt-secreting species) in a coastal lagoon in the upper section of the Maracaibo strait in western...

Controls on the chemical composition of saline surface crusts and emitted dust from a wet playa in the Mojave Desert (USA)

USGS Publications Warehouse

Goldstein, Harland L.; Breit, George N.; Reynolds, Richard L.

2017-01-01

Saline-surface crusts and their compositions at ephemeral, dry, and drying lakes are important products of arid-land processes. Detailed understanding is lacking, however, about interactions among locally variable hydrogeologic conditions, compositional control of groundwater on vadose zone and surface salts, and dust composition. Chemical and physical data from groundwater, sediments, and salts reveal compositional controls on saline-surface crusts across a wet playa, Mojave Desert, with bearing on similar settings elsewhere. The compositions of chemically and isotopically distinctive shallow (<3 m) water masses are recorded in the composition of associated salts. In areas with deeper and more saline groundwater, however, not all ions are transported through the vadose zone. Retention of arsenic and other elements in the vadose zone diminishes the concentrations of potentially toxic elements in surface salts, but creates a reservoir of these elements that may be brought to the surface during wetter conditions or by human disturbance. Selective wind-erosion loss of sulfate salts was identified by the compositional contrast between surface salt crusts and underlying groundwater. At the sub-basin scale, compositional links exist among groundwater, salt crusts, and dust from wet playas. Across the study basin, however, lateral variations in groundwater and solid-salt compositions are produced by hydrogeologic heterogeneity.

Magnetic Analysis Techniques Applied to Desert Varnish

NASA Technical Reports Server (NTRS)

Schmidgall, E. R.; Moskowitz, B. M.; Dahlberg, E. D.; Kuhlman, K. R.

2003-01-01

Desert varnish is a black or reddish coating commonly found on rock samples from arid regions. Typically, the coating is very thin, less than half a millimeter thick. Previous research has shown that the primary components of desert varnish are silicon oxide clay minerals (60%), manganese and iron oxides (20-30%), and trace amounts of other compounds [1]. Desert varnish is thought to originate when windborne particles containing iron and manganese oxides are deposited onto rock surfaces where manganese oxidizing bacteria concentrate the manganese and form the varnish [4,5]. If desert varnish is indeed biogenic, then the presence of desert varnish on rock surfaces could serve as a biomarker, indicating the presence of microorganisms. This idea has considerable appeal, especially for Martian exploration [6]. Magnetic analysis techniques have not been extensively applied to desert varnish. The only previous magnetic study reported that based on room temperature demagnetization experiments, there were noticeable differences in magnetic properties between a sample of desert varnish and the substrate sandstone [7]. Based upon the results of the demagnetization experiments, the authors concluded that the primary magnetic component of desert varnish was either magnetite (Fe3O4) or maghemite ( Fe2O3).

Strong Control of Salts on Near Surface Liquid Water Content in a High Polar Desert Indicated by Near Surface Resistivity Mapping with a Helicopter-Borne TEM Sensor, Lower Taylor Valley, Antarctica

NASA Astrophysics Data System (ADS)

Foley, N.; Tulaczyk, S. M.; Auken, E.; Mikucki, J.; Myers, K. F.; Dugan, H.; Doran, P. T.; Virginia, R. A.

2016-12-01

Closed depressions in the Lower Taylor Valley (McMurdo Dry Valleys, Antarctica) have near surface (top 5m) electrical resistivity that is lower by about an order of magnitude than the resistivity of nearby slopes and ridges (100s of ohm-m vs. 1000s). We interpret this spatial pattern as being due to long term concentration of salts carried by liquid water and/or deliquescent vapor fronts. High concentration of salts in the top decimeters to meters beneath the surface may prolong the existence and abundance of liquid water in this otherwise very cold and dry high polar desert. Due to its connections with life and chemical transport, liquid water is a much studied feature in the McMurdo Dry Valleys. This setting can be used as an analogue for similar features on the surface of Mars, where liquid water tracks have been observed and are believed to be controlled by eutectic brines. Our study demonstrates the utility of mapping at a regional scale via helicopter-borne Transient EM. Airborne EM covers more ground and can measure deeper than surface-based measurements, at the expense of resolution. This allows creating valley-scale datasets which could not feasibly be collected on the ground. Our remote measurements complement physical samples that indicate that soluble salts concentrate in certain areas of surface soil where water moves ions and is later removed by evaporation or sublimation. In areas where we measured low resistivity, the integrated liquid water fraction in the top 5m may be a few to several percent by volume, equivalent to a few or several dozens of cm of water layer thickness. This estimate assumes that the interstitial waters have very low resistivity, comparable to seawater or hypersaline brines at freezing (0.2-0.35 ohm-m). If soil water was considerably fresher than this, liquid water content would have to reach dozens of percent throughout the top 5m for bulk resistivities to drop to 100s of ohm-m. We consider the latter case to be unlikely as

Recent trends of desert tortoise populations in the Mojave Desert

USGS Publications Warehouse

Corn, Paul Stephen

1994-01-01

The desert tortoise, Gopherus agassizii (Cooper), was listed as threatened in the Mojave Desert in 1990. Important factors for the listing were severe recent mortality in tortoise populations and a general decline throughout this century. Recent trends in tortoise populations were examined by plotting total captures of adult and juvenile tortoises from 2.6-km2 study plots, rather than by mark-and-recapture population estimates. Changes in relative abundance of tortoises were greatest among large tortoises in the western Mojave Desert, which may reflect high levels of human disturbance, and among small tortoises, which may reflect either lower ability of searches to detect small tortoises or greater mortality of tortoises during drought conditions in 1986-90, or both factors. Further collection of data on population trends is needed, particularly in years with higher-than-average precipitation. Retention of the threatened status of the tortoise is a conservative strategy for the conservation of natural resources but should be reassessed when additional data are available.

Endolithic microbial life in hot and cold deserts

NASA Technical Reports Server (NTRS)

Friedmann, E. I.

1980-01-01

Endolithic microorganisms (those living inside rocks) occur in hot and cold deserts and exist under extreme environmental conditions. These conditions are discussed on a comparative basis. Quantitative estimates of biomass are comparable in hot and cold deserts. Despite the obvious differences between the hot and cold desert environment, survival strategies show some common features. These endolithic organisms are able to 'switch' rapidly their metabolic activities on and off in response to changes in the environment. Conditions in hot deserts impose a more severe environmental stress on the organisms than in the cold Antarctic desert. This is reflected in the composition of the microbial flora which in hot desert rocks consist entirely of prokaryotic microorganisms, while under cold desert conditions eukaryotes predominate.

Endophytic Fungi from Frankincense Tree Improves Host Growth and Produces Extracellular Enzymes and Indole Acetic Acid.

PubMed

Khan, Abdul Latif; Al-Harrasi, Ahmed; Al-Rawahi, Ahmed; Al-Farsi, Zainab; Al-Mamari, Aza; Waqas, Muhammad; Asaf, Sajjad; Elyassi, Ali; Mabood, Fazal; Shin, Jae-Ho; Lee, In-Jung

2016-01-01

Boswellia sacra, an economically important frankincense-producing tree found in the desert woodlands of Oman, is least known for its endophytic fungal diversity and the potential of these fungi to produce extracellular enzymes and auxins. We isolated various fungal endophytes belonging to Eurotiales (11.8%), Chaetomiaceae (17.6%), Incertae sadis (29.5%), Aureobasidiaceae (17.6%), Nectriaceae (5.9%) and Sporomiaceae (17.6%) from the phylloplane (leaf) and caulosphere (stem) of the tree. Endophytes were identified using genomic DNA extraction, PCR amplification and sequencing the internal transcribed spacer regions, whereas a detailed phylogenetic analysis of the same gene fragment was made with homologous sequences. The endophytic colonization rate was significantly higher in the leaf (5.33%) than the stem (0.262%). The Shannon-Weiner diversity index was H' 0.8729, while Simpson index was higher in the leaf (0.583) than in the stem (0.416). Regarding the endophytic fungi's potential for extracellular enzyme production, fluorogenic 4-methylumbelliferone standards and substrates were used to determine the presence of cellulases, phosphatases and glucosidases in the pure culture. Among fungal strains, Penicillum citrinum BSL17 showed significantly higher amounts of glucosidases (62.15±1.8 μM-1min-1mL) and cellulases (62.11±1.6 μM-1min-1mL), whereas Preussia sp. BSL10 showed significantly higher secretion of glucosidases (69.4±0.79 μM-1min-1mL) and phosphatases (3.46±0.31μM-1min-1mL) compared to other strains. Aureobasidium sp. BSS6 and Preussia sp. BSL10 showed significantly higher potential for indole acetic acid production (tryptophan-dependent and independent pathways). Preussia sp. BSL10 was applied to the host B. sacra tree saplings, which exhibited significant improvements in plant growth parameters and accumulation of photosynthetic pigments. The current study concluded that endophytic microbial resources producing extracellular enzymes and auxin could

Endophytic Fungi from Frankincense Tree Improves Host Growth and Produces Extracellular Enzymes and Indole Acetic Acid

PubMed Central

Khan, Abdul Latif; Al-Harrasi, Ahmed; Al-Rawahi, Ahmed; Al-Farsi, Zainab; Al-Mamari, Aza; Waqas, Muhammad; Asaf, Sajjad; Elyassi, Ali; Mabood, Fazal; Shin, Jae-Ho; Lee, In-Jung

2016-01-01

Boswellia sacra, an economically important frankincense-producing tree found in the desert woodlands of Oman, is least known for its endophytic fungal diversity and the potential of these fungi to produce extracellular enzymes and auxins. We isolated various fungal endophytes belonging to Eurotiales (11.8%), Chaetomiaceae (17.6%), Incertae sadis (29.5%), Aureobasidiaceae (17.6%), Nectriaceae (5.9%) and Sporomiaceae (17.6%) from the phylloplane (leaf) and caulosphere (stem) of the tree. Endophytes were identified using genomic DNA extraction, PCR amplification and sequencing the internal transcribed spacer regions, whereas a detailed phylogenetic analysis of the same gene fragment was made with homologous sequences. The endophytic colonization rate was significantly higher in the leaf (5.33%) than the stem (0.262%). The Shannon-Weiner diversity index was H′ 0.8729, while Simpson index was higher in the leaf (0.583) than in the stem (0.416). Regarding the endophytic fungi’s potential for extracellular enzyme production, fluorogenic 4-methylumbelliferone standards and substrates were used to determine the presence of cellulases, phosphatases and glucosidases in the pure culture. Among fungal strains, Penicillum citrinum BSL17 showed significantly higher amounts of glucosidases (62.15±1.8 μM-1min-1mL) and cellulases (62.11±1.6 μM-1min-1mL), whereas Preussia sp. BSL10 showed significantly higher secretion of glucosidases (69.4±0.79 μM-1min-1mL) and phosphatases (3.46±0.31μM-1min-1mL) compared to other strains. Aureobasidium sp. BSS6 and Preussia sp. BSL10 showed significantly higher potential for indole acetic acid production (tryptophan-dependent and independent pathways). Preussia sp. BSL10 was applied to the host B. sacra tree saplings, which exhibited significant improvements in plant growth parameters and accumulation of photosynthetic pigments. The current study concluded that endophytic microbial resources producing extracellular enzymes and auxin

The dynamics of secretion during sea urchin embryonic skeleton formation.

PubMed

Wilt, Fred H; Killian, Christopher E; Hamilton, Patricia; Croker, Lindsay

2008-05-01

Skeleton formation involves secretion of massive amounts of mineral precursor, usually a calcium salt, and matrix proteins, many of which are deposited on, or even occluded within, the mineral. The cell biological underpinnings of this secretion and subsequent assembly of the biomineralized skeletal element is not well understood. We ask here what is the relationship of the trafficking and secretion of the mineral and matrix within the primary mesenchyme cells of the sea urchin embryo, cells that deposit the endoskeletal spicule. Fluorescent labeling of intracellular calcium deposits show mineral precursors are present in granules visible by light microscopy, from whence they are deposited in the endoskeletal spicule, especially at its tip. In contrast, two different matrix proteins tagged with GFP are present in smaller post-Golgi vesicles only seen by electron microscopy, and the secreted protein are only incorporated into the spicule in the vicinity of the cell of origin. The matrix protein, SpSM30B, is post-translationally modified during secretion, and this processing continues after its incorporation into the spicule. Our findings also indicate that the mineral precursor and two well characterized matrix proteins are trafficked by different cellular routes.

The Dynamics of Secretion during Sea Urchin Embryonic Skeleton Formation

PubMed Central

Wilt, Fred H.; Killian, Christopher E.; Hamilton, Patricia; Croker, Lindsay

2008-01-01

Skeleton formation involves secretion of massive amounts of mineral precursor, usually a calcium salt, and matrix proteins, many of which are deposited on, or even occluded within, the mineral. The cell biological underpinnings of this secretion and subsequent assembly of the biomineralized skeletal element is not well understood. We ask here what is the relationship of the trafficking and secretion of the mineral and matrix within the primary mesenchyme cells of the sea urchin embryo, cells that deposit the endoskeletal spicule. Fluorescent labeling of intracellular calcium deposits show mineral precursors are present in granules visible by light microscopy, from whence they are deposited in the endoskeletal spicule, especially at its tip. In contrast, two different matrix proteins tagged with GFP are present in smaller post-Golgi vesicles only seen by electron microscopy, and the secreted protein are only incorporated into the spicule in the vicinity of the cell of origin. The matrix protein, SpSM30B, is post-translationally modified during secretion, and this processing continues after its incorporation into the spicule. Our findings also indicate that the mineral precursor and two well characterized matrix proteins are trafficked by different cellular routes. PMID:18355808

Impacts of atmospheric nitrogen deposition on vegetation and soils in Joshua Tree National Park

Treesearch

E.B. Allen; L. Rao; R.J. Steers; A. Bytnerowicz; M.E. Fenn

2009-01-01

The western Mojave Desert is downwind of nitrogen emissions from coastal and inland urban sources, especially automobiles. The objectives of this research were to measure reactive nitrogen (N) in the atmosphere and soils along a N-deposition gradient at Joshua Tree National Park and to examine its effects on invasive and native plant species. Atmospheric nitric acid (...

Navajo Code Talker Joe Morris, Sr. shared insights from his time as a secret World War Two messenger with his audience at NASA's Dryden Flight Research Center

NASA Image and Video Library

2002-11-26

Navajo Code Talker Joe Morris, Sr. shared insights from his time as a secret World War Two messenger with his audience at NASA's Dryden Flight Research Center on Nov. 26, 2002. NASA Dryden is located on Edwards Air Force Base in California's Mojave Desert.

Soil processes evolved by the establishment of tree plantations on croplands/grasslands - evaluation of afforestation effect on the Great Plain (Hungary)

NASA Astrophysics Data System (ADS)

Balog, Kitti; Szabó, András; Gribovszki, Zoltán; Tóth, Tibor

2016-04-01

In Hungary, there was a great increase in the acreage of forested areas during the last century (1.1 to 1.8 million ha). Most of the plantations were established on non-profitable grasslands/croplands (National Forest Strategy, 2009). The forests affect hydrologic and climatic elements of the physical habitat and induce alterations in the soil properties, as well. Soil and groundwater of 70 plantations (Poplar, Common oak and Black locust) and nearby control plots (grassland/cropland) - representing former land use - were investigated over the Great Hungarian Plain. Sampling sites were located by a gradient of climatic water balance, initial water table depth and salinity, soil layering, tree species and plantation age. Short- and long-term effects in groundwater levels (GWL) were found under the woody vegetation. GWL depression evolved beneath forests (poplar and oak provably) compared to control, in 78.8% of the cases. GWL depression was the most significant in the growing season, then the difference between GWLs decreased. Since evapotranspiration (ET) is the main driving force for water consumption of trees, and the ET of trees can be three times higher than that of the grassy control in the growing season, greater (ground)water uptake could be measured, giving rise to higher GWL depression. Short-term effect of the plantation was the daily fluctuation of GWL in the woods that can be twice as much as that of the control. Water uptake is influenced by the type of the groundwater zone (recharge/discharge), where the sample area is located, and by tree species (diverse water demands). Afforestation raised the salt content of the groundwater slightly. In 52.9 % of the cases, salt content of groundwater was higher under the forest, than under the control. Below the forests, salts concentrated in the soil profile and formed a salt accumulation zone surrounding the root zone. In 52.9 % of the cases, salts accumulated in the profile: in the subsoil under the trees (3

Diversity of ionizing radiation-resistant bacteria obtained from the Taklimakan Desert.

PubMed

Yu, Li Zhi-Han; Luo, Xue-Song; Liu, Ming; Huang, Qiaoyun

2015-01-01

So far, little is known about the diversity of the radiation-resistant microbes of the hyperarid Taklimakan Desert. In this study, ionizing radiation (IR)-resistant bacteria from two sites in Xinjiang were investigated. After exposing the arid (water content of 0.8 ± 0.3%) and non-arid (water content of 21.3 ± 0.9%) sediment samples to IR of 3000 Gy using a (60)Co source, a total of 52 γ-radiation-resistant bacteria were isolated from the desert sample. The 16S rRNA genes of all isolates were sequenced. The phylogenetic tree places these isolates into five groups: Cytophaga-Flavobacterium-Bacteroides, Proteobacteria, Deinococcus-Thermus, Firmicutes, and Actinobacteria. Interestingly, this is the first report of radiation-resistant bacteria belonging to the genera Knoellia, Lysobacter, Nocardioides, Paracoccus, Pontibacter, Rufibacter and Microvirga. The 16s rRNA genes of four isolates showed low sequence similarities to those of the published species. Phenotypic analysis showed that all bacteria in this study are able to produce catalase, suggesting that these bacteria possess reactive oxygen species (ROS)-scavenging enzymes. These radiation-resistant bacteria also displayed diverse metabolic properties. Moreover, their radiation resistances were found to differ. The diversity of the radiation-resistant bacteria in the desert provides further ecological support for the hypothesis that the ionizing-radiation resistance phenotype is a consequence of the evolution of ROS-scavenging systems that protect cells against oxidative damage caused by desiccation. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Severe acute dehydration in a desert rodent elicits a transcriptional response that effectively prevents kidney injury.

PubMed

MacManes, Matthew David

2017-08-01

Animals living in desert environments are forced to survive despite severe heat, intense solar radiation, and both acute and chronic dehydration. These animals have evolved phenotypes that effectively address these environmental stressors. To begin to understand the ways in which the desert-adapted rodent Peromyscus eremicus survives, reproductively mature adults were subjected to 72 h of water deprivation, during which they lost, on average, 23% of their body weight. The animals reacted via a series of changes in the kidney, which included modulating expression of genes responsible for reducing the rate of transcription and maintaining water and salt balance. Extracellular matrix turnover appeared to be decreased, and apoptosis was limited. In contrast to the canonical human response, serum creatinine and other biomarkers of kidney injury were not elevated, suggesting that changes in gene expression related to acute dehydration may effectively prohibit widespread kidney damage in the cactus mouse. Copyright © 2017 the American Physiological Society.

Hot bats: extreme thermal tolerance in a desert heat wave

NASA Astrophysics Data System (ADS)

Bondarenco, Artiom; Körtner, Gerhard; Geiser, Fritz

2014-08-01

Climate change is predicted to increase temperature extremes and thus thermal stress on organisms. Animals living in hot deserts are already exposed to high ambient temperatures ( T a) making them especially vulnerable to further warming. However, little is known about the effect of extreme heat events on small desert mammals, especially tree-roosting microbats that are not strongly protected from environmental temperature fluctuations. During a heat wave with record T as at Sturt National Park, we quantified the thermal physiology and behaviour of a single free-ranging little broad-nosed ( Scotorepens greyii, henceforth Scotorepens) and two inland freetail bats ( Mormopterus species 3, henceforth Mormopterus) using temperature telemetry over 3 days. On 11 and 13 January, maximum T a was ˜45.0 °C, and all monitored bats were thermoconforming. On 12 January 2013, when T a exceeded 48.0 °C, Scotorepens abandoned its poorly insulated roost during the daytime, whereas both Mormopterus remained in their better insulated roosts and were mostly thermoconforming. Maximum skin temperatures ( T skin) ranged from 44.0 to 44.3 °C in Scotorepens and from 40.0 to 45.8 °C in Mormopterus, and these are the highest T skin values reported for any free-ranging bat. Our study provides the first evidence of extensive heat tolerance in free-ranging desert microbats. It shows that these bats can tolerate the most extreme T skin range known for mammals (3.3 to 45.8 °C) and delay regulation of T skin by thermoconforming over a wide temperature range and thus decrease the risks of dehydration and consequently death.

Hot bats: extreme thermal tolerance in a desert heat wave.

PubMed

Bondarenco, Artiom; Körtner, Gerhard; Geiser, Fritz

2014-08-01

Climate change is predicted to increase temperature extremes and thus thermal stress on organisms. Animals living in hot deserts are already exposed to high ambient temperatures (T a) making them especially vulnerable to further warming. However, little is known about the effect of extreme heat events on small desert mammals, especially tree-roosting microbats that are not strongly protected from environmental temperature fluctuations. During a heat wave with record T as at Sturt National Park, we quantified the thermal physiology and behaviour of a single free-ranging little broad-nosed (Scotorepens greyii, henceforth Scotorepens) and two inland freetail bats (Mormopterus species 3, henceforth Mormopterus) using temperature telemetry over 3 days. On 11 and 13 January, maximum T a was ∼45.0 °C, and all monitored bats were thermoconforming. On 12 January 2013, when T a exceeded 48.0 °C, Scotorepens abandoned its poorly insulated roost during the daytime, whereas both Mormopterus remained in their better insulated roosts and were mostly thermoconforming. Maximum skin temperatures (T skin) ranged from 44.0 to 44.3 °C in Scotorepens and from 40.0 to 45.8 °C in Mormopterus, and these are the highest T skin values reported for any free-ranging bat. Our study provides the first evidence of extensive heat tolerance in free-ranging desert microbats. It shows that these bats can tolerate the most extreme T skin range known for mammals (3.3 to 45.8 °C) and delay regulation of T skin by thermoconforming over a wide temperature range and thus decrease the risks of dehydration and consequently death.

Recovery of symbiotic nitrogen fixing acacia rhizobia from Merzouga Desert sand dunes in South East Morocco--Identification of a probable new species of Ensifer adapted to stressed environments.

PubMed

Sakrouhi, Ilham; Belfquih, Meryem; Sbabou, Laïla; Moulin, Patricia; Bena, Gilles; Filali-Maltouf, Abdelkarim; Le Quéré, Antoine

2016-03-01

Bacteria capable of nodulating Acacia tortilis and A. gummifera could be recovered from sand dunes collected in the Moroccan Merzouga desert. The trapping approach enabled the recovery of 17 desert rhizobia that all clustered within the Ensifer (Sinorhizobium) genus. Four isolates of the dominant genotype comprising 15 strains as well as 2 divergent strains were further characterized by MLSA. Phylogenetic analyzes indicated that the dominant genetic type was belonging to a new and yet undefined species within the Ensifer genus. Interestingly, housekeeping gene phylogenies showed that this possibly new species is also present in another desert but in India. Phylogenetic analyses of nifH and nodC sequences showed high sequence conservation among the Moroccan strains belonging to the dominant genotype but high divergence with sequences from Indian isolates suggesting acquisition of symbiotic genes through Horizontal Gene Transfer. These desert rhizobia were capable of growing in media containing high salt concentrations, under high pH and most of the strains showed growth at 45°C. Only recovered from desert type of Biome, yet, this new taxon appears particularly adapted to such harsh environment. Copyright © 2016 Elsevier GmbH. All rights reserved.

A method for assessing the physical recovery of Antarctic desert pavements following human-induced disturbances: a case study in the Ross Sea region of Antarctica.

PubMed

O'Neill, Tanya A; Balks, Megan R; López-Martínez, Jerónimo; McWhirter, Judi L

2012-12-15

With increasing visitor numbers an understanding of the impacts of human activities in Antarctic terrestrial environments has become important. The objective of this study was to develop a means for assessing recovery of the ground surface desert pavement following physical disturbance. A set of 11 criteria were identified to assess desert pavement recovery. Assessed criteria were: embeddedness of surface clasts; impressions of removed clasts; degree of clast surface weathering; % overturned clasts; salt on underside of clasts; development of salt coatings; armouring per m(2); colour contrast; evidence of subsidence/melt out; accumulation of salt on cut surfaces; and evidence of patterned ground development. Recovery criteria were assigned a severity/extent rating on a scale from zero to four, zero being highly disturbed, and four being undisturbed. A relative % recovery for each criteria was calculated for each site by comparison with a nearby undisturbed control area, and an overall Mean Recovery Index (MRI) was assigned to each pavement surface. To test the method, 54 sites in the Ross Sea region of Antarctica were investigated including areas disturbed by: bulldozer scraping for road-fill, contouring for infrastructure, geotechnical investigations, and experimental treading trial sites. Disturbances had occurred at timescales ranging from one week to 50 years prior to assessment. The extent of desert pavement recovery at the sites investigated in this study was higher than anticipated. Fifty of the 54 sites investigated were in an intermediate, or higher, stage of desert pavement recovery, 30 sites were in an advanced stage of recovery, and four sites were indistinguishable from adjacent control sites (MRI = 100%). It was found that active surfaces, such as the gravel beach deposits at the Greenpeace World Park Base site at Cape Evans, the aeolian sand deposits at Bull Pass, and the alluvial fan deposits of the Loop Moraine field campsite, recovered relatively

HIGH FOLIAR NITROGEN IN DESERT SHRUBS: AN IMPORTANT ECOSYSTEM TRAIT OR DEFECTIVE DESERT DOCTRINE?

EPA Science Inventory

Nitrogen concentrations in green and senesced leaves of perennial desert shrubs were compiled from a worldwide literature search to test the validity of the doctrine that desert shrubs produce foliage and leaf litter much richer in nitrogen than that in the foliage of plants from...

Effect of bismuth subcitrate on amphibian gastroduodenal bicarbonate secretion.

PubMed Central

Shorrock, C J; Crampton, J R; Gibbons, L C; Rees, W D

1989-01-01

The ulcer healing and cytoprotective properties of colloidal bismuth (De-Nol) are well established although its mode of action is unclear. We have examined the action of bismuth subcitrate, the active ingredient of De-Nol, on gastroduodenal bicarbonate secretion by isolated amphibian mucosa. Addition of bismuth subcitrate (10(-6) to 10(-4) M) to the luminal solution produced a dose dependent increase in bicarbonate secretion from both gastric and duodenal mucosae without a change in transmucosal potential difference. The magnitude of this stimulation was greater for gastric than duodenal mucosae at all dose ranges. A second bismuth salt, bismuth oxynitrate, produced similar increases in bicarbonate secretion from gastric mucosae. Pretreatment of gastric mucosa with the cyclooxygenase inhibitor, indomethacin (10(-5) and 10(-4) M), did not abolish the secretory response to bismuth subcitrate. Similar treatment with the chloride transport inhibitor, 4-acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic acid (SITS) (10(-3) M) prevented the secretory response to bismuth subcitrate. PMID:2788112

Profile Changes in the Soil Microbial Community When Desert Becomes Oasis

PubMed Central

Li, Chen-hua; Tang, Li-song; Jia, Zhong-jun; Li, Yan

2015-01-01

The conversion of virgin desert into oasis farmland creates two contrasting types of land-cover. During oasis formation with irrigation and fertilizer application, however, the changes in the soil microbial population, which play critical roles in the ecosystem, remain poorly understood. We applied high-throughput pyrosequencing to investigate bacterial and archaeal communities throughout the profile (0–3 m) in an experimental field, where irrigation and fertilization began in 1990 and cropped with winter wheat since then. To assess the effects of cultivation, the following treatments were compared with the virgin desert: CK (no fertilizer), PK, NK, NP, NPK, NPKR, and NPKM (R: straw residue; M: manure fertilizer). Irrigation had a greater impact on the overall microbial community than fertilizer application. The greatest impact occurred in topsoil (0–0.2 m), e.g., Cyanobacteria (25% total abundance) were most abundant in desert soil, while Actinobacteria (26%) were most abundant in oasis soil. The proportions of extremophilic and photosynthetic groups (e.g., Deinococcus-Thermus and Cyanobacteria) decreased, while the proportions of R-strategy (e.g., Gammaproteobacteria including Xanthomonadales), nitrifying (e.g., Nitrospirae), and anaerobic bacteria (e.g., Anaerolineae) increased throughout the oasis profile. Archaea occurred only in oasis soil. The impact of fertilizer application was mainly reflected in the non-dominant communities or finer taxonomic divisions. Oasis formation led to a dramatic shift in microbial community and enhanced soil enzyme activities. The rapidly increased soil moisture and decreased salt caused by irrigation were responsible for this shift. Furthermore, difference in fertilization and crop growth altered the organic carbon contents in the soil, which resulted in differences of microbial communities within oasis. PMID:26426279

Desert tortoise use of burned habitat in the Eastern Mojave desert

USGS Publications Warehouse

Drake, Karla K.; Esque, Todd C.; Nussear, Kenneth E.; DeFalco, Lesley; Scoles, Sara; Modlin, Andrew T.; Medica, Philip A.

2015-01-01

Wildfires burned 24,254 ha of critical habitat designated for the recovery of the threatened Mojave desert tortoise (Gopherus agassizii) in southern Nevada during 2005. The proliferation of non-native annual grasses has increased wildfire frequency and extent in recent decades and continues to accelerate the conversion of tortoise habitat across the Mojave Desert. Immediate changes to vegetation are expected to reduce quality of critical habitat, yet whether tortoises will use burned and recovering habitat differently from intact unburned habitat is unknown. We compared movement patterns, home-range size, behavior, microhabitat use, reproduction, and survival for adult desert tortoises located in, and adjacent to, burned habitat to understand how tortoises respond to recovering burned habitat. Approximately 45% of home ranges in the post-fire environment contained burned habitat, and numerous observations (n = 12,223) corroborated tortoise use of both habitat types (52% unburned, 48% burned). Tortoises moved progressively deeper into burned habitat during the first 5 years following the fire, frequently foraging in burned habitats that had abundant annual plants, and returning to adjacent unburned habitat for cover provided by intact perennial vegetation. However, by years 6 and 7, the live cover of the short-lived herbaceous perennial desert globemallow (Sphaeralcea ambigua) that typically re-colonizes burned areas declined, resulting in a contraction of tortoise movements from the burned areas. Health and egg production were similar between burned and unburned areas indicating that tortoises were able to acquire necessary resources using both areas. This study documents that adult Mojave desert tortoises continue to use habitat burned once by wildfire. Thus, continued management of this burned habitat may contribute toward the recovery of the species in the face of many sources of habitat loss.

Hyperarid Soils in the Atacama Desert: A Terrestrial Guide to Mars Soil Formation

NASA Astrophysics Data System (ADS)

Amundson, R.; Stephanie, E.; Justine, O.; Brad, S.; Nishiizumi, K.; William, D.; Chris, M.

2005-12-01

Hyperarid soils on Earth provide a framework for interpreting the growing Mars regolith database and for developing testable hypotheses for the origin of Mars soils. On Earth, dust and aerosol deposition are strongly coupled with soil formation. Long term atmospheric deposition in the Atacama Desert, coupled with small and highly stochastic rain and fog events, produce a set of soil features diagnostic of pedogenic processes and indicative of the direction of liquid water flow: (1) Extreme hyperaridity results in the retention of nearly all atmospheric inputs within the upper 3 m of the soil profile, but the infrequent rainfall events vertically separate salts by solubility, forming polygonally cracked, sulfate-cemented near-surface crusts which overlie variably concentrated layers of the more soluble chloride, nitrate, and Na-sulfate salts. (2) Pedogenic sulfates in the Atacama desert exhibit unique depth-dependent S, O and Ca isotope trends caused by isotopic fractionation during downward aqueous migration and chemical reaction. (3) Pedogenic sulfates and nitrates contain a distinctive mass independent O isotope signal indicative of a tropospheric origin, and in the case of nitrate, the retention of this signal persists only under near-abiotic conditions. Taken together, the morphology and the depth-dependent chemical and isotopic composition of hyperarid soils provides quantitative information on the origin of solutes, direction of water flow, and degree of biological activity. Depth-dependent measures of these parameters on Mars can therefore be used to test a pedogenic hypothesis for the origin of the widely distributed sulfate layers and can be used to design experiments for future missions that may more fully illuminate the history of Mars surface processes.

Colonization patterns of soil microbial communities in the Atacama Desert.

PubMed

Crits-Christoph, Alexander; Robinson, Courtney K; Barnum, Tyler; Fricke, W Florian; Davila, Alfonso F; Jedynak, Bruno; McKay, Christopher P; Diruggiero, Jocelyne

2013-11-20

The Atacama Desert is one of the driest deserts in the world and its soil, with extremely low moisture, organic carbon content, and oxidizing conditions, is considered to be at the dry limit for life. Analyses of high throughput DNA sequence data revealed that bacterial communities from six geographic locations in the hyper-arid core and along a North-South moisture gradient were structurally and phylogenetically distinct (ANOVA test for observed operating taxonomic units at 97% similarity (OTU0.03), P <0.001) and that communities from locations in the hyper-arid zone displayed the lowest levels of diversity. We found bacterial taxa similar to those found in other arid soil communities with an abundance of Rubrobacterales, Actinomycetales, Acidimicrobiales, and a number of families from the Thermoleophilia. The extremely low abundance of Firmicutes indicated that most bacteria in the soil were in the form of vegetative cells. Integrating molecular data with climate and soil geochemistry, we found that air relative humidity (RH) and soil conductivity significantly correlated with microbial communities' diversity metrics (least squares linear regression for observed OTU0.03 and air RH and soil conductivity, P <0.001; UniFrac PCoA Spearman's correlation for air RH and soil conductivity, P <0.0001), indicating that water availability and salt content are key factors in shaping the Atacama soil microbiome. Mineralization studies showed communities actively metabolizing in all soil samples, with increased rates in soils from the southern locations. Our results suggest that microorganisms in the driest soils of the Atacama Desert are in a state of stasis for most of the time, but can potentially metabolize if presented with liquid water for a sufficient duration. Over geological time, rare rain events and physicochemical factors potentially played a major role in selecting micro-organisms that are most adapted to extreme desiccating conditions.

Colonization patterns of soil microbial communities in the Atacama Desert

PubMed Central

2013-01-01

Background The Atacama Desert is one of the driest deserts in the world and its soil, with extremely low moisture, organic carbon content, and oxidizing conditions, is considered to be at the dry limit for life. Results Analyses of high throughput DNA sequence data revealed that bacterial communities from six geographic locations in the hyper-arid core and along a North-South moisture gradient were structurally and phylogenetically distinct (ANOVA test for observed operating taxonomic units at 97% similarity (OTU0.03), P <0.001) and that communities from locations in the hyper-arid zone displayed the lowest levels of diversity. We found bacterial taxa similar to those found in other arid soil communities with an abundance of Rubrobacterales, Actinomycetales, Acidimicrobiales, and a number of families from the Thermoleophilia. The extremely low abundance of Firmicutes indicated that most bacteria in the soil were in the form of vegetative cells. Integrating molecular data with climate and soil geochemistry, we found that air relative humidity (RH) and soil conductivity significantly correlated with microbial communities’ diversity metrics (least squares linear regression for observed OTU0.03 and air RH and soil conductivity, P <0.001; UniFrac PCoA Spearman’s correlation for air RH and soil conductivity, P <0.0001), indicating that water availability and salt content are key factors in shaping the Atacama soil microbiome. Mineralization studies showed communities actively metabolizing in all soil samples, with increased rates in soils from the southern locations. Conclusions Our results suggest that microorganisms in the driest soils of the Atacama Desert are in a state of stasis for most of the time, but can potentially metabolize if presented with liquid water for a sufficient duration. Over geological time, rare rain events and physicochemical factors potentially played a major role in selecting micro-organisms that are most adapted to extreme desiccating

Inappropriate secretion of antidiuretic hormone treated with frusemide.

PubMed Central

Decaux, G; Waterlot, Y; Genette, F; Hallemans, R; Demanet, J C

1982-01-01

Seven out of nine patients with chronic inappropriate secretion of antidiuretic hormone were successfully treated with 40 mg frusemide daily. One patient needed 80 mg, and the remaining patient achieved only a small increase in diuresis after 40 mg frusemide; this was probably related to his low creatinine clearance. In order to maintain a salt intake high enough to compensate for the loss of urine electrolytes 3 to 6 g sodium chloride was added as tablets to the sodium-free diet in six patients. Hypokalaemia occurred in five patients but was easily corrected with either supplements of potassium chloride or a potassium-sparing diuretic. These findings add further weight to evidence that Frusemide is a good alternative for the treatment of patients with inappropriate secretion of antidiuretic hormone who cannot tolerate water restriction. PMID:6805839

Inappropriate secretion of antidiuretic hormone treated with frusemide.

PubMed

Decaux, G; Waterlot, Y; Genette, F; Hallemans, R; Demanet, J C

1982-07-10

Seven out of nine patients with chronic inappropriate secretion of antidiuretic hormone were successfully treated with 40 mg frusemide daily. One patient needed 80 mg, and the remaining patient achieved only a small increase in diuresis after 40 mg frusemide; this was probably related to his low creatinine clearance. In order to maintain a salt intake high enough to compensate for the loss of urine electrolytes 3 to 6 g sodium chloride was added as tablets to the sodium-free diet in six patients. Hypokalaemia occurred in five patients but was easily corrected with either supplements of potassium chloride or a potassium-sparing diuretic. These findings add further weight to evidence that Frusemide is a good alternative for the treatment of patients with inappropriate secretion of antidiuretic hormone who cannot tolerate water restriction.

Desert Tortoise (Gopherus agassizii)

USGS Publications Warehouse

Boarman, William I.; Boarman, William I.; Beaman, K.

2002-01-01

The desert tortoise is widely distributed throughout major portions of the Mojave and Sonoran deserts of California, Nevada, Utah, Arizona, Sonora, and Sinaloa. Genetic, morphological, ecological, and behavioral features suggest an evolutionary divergence between the tortoises found south and east of the Colorado River (“Sonoran population”), and those found north and west of the river (“Mojave population;” Lamb et al. 1989). The latter is the population Federally and State-listed as threatened. This population will be referred to in the remainder of this account. The majority of animals in the Mojave population occur at variable densities in six distinct population segments (i.e., evolutionarily significant units), each identified in the Recovery Plan for desert tortoises as separate Recovery Units (USFWS 1994).

Stable sulfur isotope hydrogeochemical studies using desert shrubs and tree rings, Death Valley, California, USA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Wenbo; Spencer, R.J.; Krouse, H.R.

1996-08-01

The {delta}{sup 34}S values of two dominant xerophytes, Atriplex hymenehytra and Larrea tridentata, in Death Valley, California, vary similarly from +7 to +18{per_thousand}, corresponding isotopically to sulfate in the water supplies at a given location. Going radially outwards, tree ring data from a phreatophyte tree, Tamarix aphylla, show a distinct time dependence, with {delta}{sup 34}S values increasing from +13.5 to +18{per_thousand} for soluble sulfate and from +12 to +17% for total sulfur. These data are interpreted in terms of sulfur sources, water sources and flow paths, and tree root growth. 32 refs., 3 figs., 3 tabs.

[Effect of shifting sand burial on evaporation reduction and salt restraint under saline water irrigation in extremely arid region].

PubMed

Zhang, Jian-Guo; Zhao, Ying; Xu, Xin-Wen; Lei, Jia-Qiang; Li, Sheng-Yu; Wang, Yong-Dong

2014-05-01

The Taklimakan Desert Highway Shelterbelt is drip-irrigated with high saline groundwater (2.58-29.70 g x L(-1)), and shifting sand burial and water-salt stress are most common and serious problems in this region. So it is of great importance to study the effect of shifting sand burial on soil moisture evaporation, salt accumulation and their distribution for water saving, salinity restraint, and suitable utilization of local land and water resources. In this study, Micro-Lysimeters (MLS) were used to investigate dynamics of soil moisture and salt under different thicknesses of sand burial (1, 2, 3, 4, and 5 cm), and field control experiments of drip-irrigation were also carried out to investigate soil moisture and salt distribution under different thicknesses of shifting sand burial (5, 10, 15, 20, 25, 30, 35, and 40 cm). The soil daily and cumulative evaporation decreased with the increase of sand burial thickness in MLS, cumulative evaporation decreased by 2.5%-13.7% compared with control. And evaporative inhibiting efficiency increased with sand burial thickness, evaporative inhibiting efficiency of 1-5 cm sand burial was 16.7%-79.0%. Final soil moisture content beneath the interface of sand burial increased with sand burial thickness, and it increased by 2.5%-13.7% than control. The topsoil EC of shifting sand in MLS decreased by 1.19-6.00 mS x cm(-1) with the increasing sand burial thickness, whereas soil salt content beneath the interface in MLS increased and amplitude of the topsoil salt content was higher than that of the subsoil. Under drip-irrigation with saline groundwater, average soil moisture beneath the interface of shifting sand burial increased by 0.4% -2.0% compare with control, and the highest value of EC was 7.77 mS x cm(-1) when the sand burial thickness was 10 cm. The trend of salt accumulation content at shifting sand surface increased firstly, and then decreased with the increasing sand burial thickness. Soil salt contents beneath the

Pod mesocarp flour of North and South American species of Leguminous tree (mesquite): Composition and food applications

USDA-ARS?s Scientific Manuscript database

Flour from the mesocarp of pods of the tree legume known as mesquite (Prosopis spp.) in North America or algarrobo in South America was one of the most important food staples for desert people. Contemporary milling techniques produces a similar flour that is about 40% sucrose, 25% dietary fiber, and...

Connexin 40 is dispensable for vascular renin cell recruitment but is indispensable for vascular baroreceptor control of renin secretion.

PubMed

Machura, Katharina; Neubauer, Bjoern; Müller, Hanna; Tauber, Philipp; Kurtz, Armin; Kurtz, Lisa

2015-08-01

Defects of the gap junction protein connexin 40 (Cx40) in renin-secreting cells (RSCs) of the kidney lead to a shift of the localization of RSCs from the media layer of afferent arterioles to the periglomerular interstitium. The dislocation of RSCs goes in parallel with elevated plasma renin levels, impaired pressure control of renin secretion, and hypertension. The reasons for the extravascular shift of RSCs and the blunted pressure regulation of renin secretion caused by the absence of Cx40 are still unclear. We have therefore addressed the question if Cx40 is essential for the metaplastic transformation of preglomerular vascular smooth muscle cells (SMCs) into RSCs and if Cx40 is essential for the pressure control of renin secretion from RSCs located in the media layer of afferent arterioles. For our study, we used mice lacking the angiotensin II type 1A (AT1A) receptors, which display a prominent and reversible salt-sensitive metaplastic transformation of SMCs into RSCs. This mouse line was crossed with Cx40-deficient mice to obtain AT1A and Cx40 double deleted mice. The kidneys of AT1A (-/-)Cx40(-/-) mice kept on normal salt (0.3 %) displayed RSCs both in the inner media layer of preglomerular vessels and in the periglomerular interstitium. In contrast to hypotensive AT1A (-/-) (mean bp syst 112 mmHg) and hypertensive Cx40(-/-) (mean bp syst 160 mmHg) mice AT1A (-/-)Cx40(-/-) mice were normotensive(mean bp syst 130 mmHg). Pressure regulation of renin secretion from isolated kidneys was normal in AT1A (-/-) mice, but was absent in AT1A (-/-)Cx40(-/-) mice alike in Cx40(-/-) mice. Low-salt diet (0.02 %) increased RSC numbers in the media layer, whilst high-salt diet (4 %) caused disappearance of RSCs in the media layer but not in the periglomerular interstitium. Blood pressure was clearly salt sensitive both in AT1A (-/-) and in AT1A (-/-)Cx40(-/-) mice but was shifted to higher pressure values in the latter genotype. Our data indicate that Cx40 is not a

Biogeochemical Heterogeneity in Mars Analog Soils from the Atacama Desert

NASA Astrophysics Data System (ADS)

Claire, M.; Shirey, B.; Brown, M.; Anderson, D.; Van Mourik, M.

2014-12-01

Water is ubiquitous on Earth and plays a fundamental role in all aspects of biogeochemical cycling. Our existence on an aqua planet hampers our ability to interpret a planet like Mars where it may not have rained for a billion years. Soils from the hyperarid core of Chile's Atacama Desert may represent the closest geochemical analog to Martian soils, as this region has the lowest precipitation on Earth. The extreme lack of rainfall (a few mm per decade) limits both weathering and biological activity to the point where soils are effectively sterile. Oxidized end products of atmospheric chemistry such as nitrate and perchlorate build up to values approaching those measured on Mars by NASA's Phoenix Lander. In June 2012, we collected soil samples from 8 locations along an aridity gradient from the hyperarid core of the Atacama (rainfall < 1 mm/yr) towards the arid (5-100 mm/yr) surrounding areas where microbial community activity is sufficient to support the hardiest of desert plant species. Field observations indicate that microbial activity and geochemical heterogeneity are anti-correlated. We will present our quantitative results coupling geochemical heterogeneity (salt concentrations, org C/N, trace metals) and microbial community activity (TRFLP, nitrogen cycling) along this transect, and argue that geochemical heterogeneity (which could be measured by a rover or lander on Mars) may be a proxy for lifeless soils.

Water quality and hydrology of the Lac Vieux Desert watershed, Gogebic County, Michigan, and Vilas County, Wisconsin, 2002-04

USGS Publications Warehouse

Weaver, T.L.; Neff, B.P.; Ellis, J.M.

2005-01-01

Lac Vieux Desert is a prominent 6.6 square-mile lake that straddles the Michigan-Wisconsin border and forms the headwaters of the Wisconsin River. For generations, the Lac Vieux Desert Band of Lake Superior Chippewa Indians have used Lac Vieux Desert and the surrounding area for growing and harvesting wild rice, and hunting and fishing. The Lac Vieux Desert Band is concerned about the impact of lake-stage regulation on hydrology and ecology, and the impact on water quality of development along and near the shore, and recreational watercraft use and sport fishing. In 2005, the U.S. Geological Survey completed a water-resources investigation of the Lac Vieux Desert watershed in cooperation with the Lac Vieux Desert Band of Lake Superior Chippewa Indians.Water quality of Lac Vieux Desert is typical of many lakes in the northern United States. Trophic State Index calculations classify Lac Vieux Desert as a highly productive eutrophic lake. The pH of water in Lac Vieux Desert ranged from 6.5 to 9.5, and specific conductance ranged from 62 to 114 µs/cm. Chloride concentration was less than 1.5 mg/L, indicating little effect from septic-tank or road-salt input. Results indicate that the water can be classified as soft, with hardness concentrations reported as calcium carbonate ranging from 29 to 49 mg/L. Concentrations of calcium, magnesium, chloride, and other dissolved solids ranged from 47 to 77 mg/L. Alkalinity of Lac Vieux Desert ranged from 27 to 38 mg/L.Pervasive aquatic blooms, including a bloom noted during the September 2003 sampling, are apparently common in late summer. Biological productivity at Lac Vieux Desert does not appear to have changed appreciably between 1973 and 2004. In the current study, total phosphorus concentrations ranged from 0.01 to 0.064 mg/L and dissolved nitrite plus nitrate nitrogen concentrations ranged from at, or below detection limit to 0.052 mg/L. Overabundance of nutrients in Lac Vieux Desert, particularly nitrogen and phosphorus

Changes in urine parameters after desert exposure: assessment of stone risk in United States Marines transiently exposed to a desert environment.

PubMed

Masterson, James H; Jourdain, Victor J; Collard, Daniel A; Choe, Chong H; Christman, Matthew S; L'Esperance, James O; Auge, Brian K

2013-01-01

Living in a desert environment has been associated with a higher incidence of kidney stone formation, likely because of concentrated urine output, higher production of vitamin D and genetic predisposition. We determined the changes in urinary parameters after a group of United States Marines temporarily transitioned from a temperate environment to a desert environment. A total of 50 Marines completed a questionnaire and performed 3, 24-hour urine collections before mobilization to the desert, after 30 days in the desert and 2 weeks after returning from the desert. Daily urine output decreased 68% to 0.52 L despite marked increased fluid intake (17 L per day). Total daily urinary excretion of calcium, uric acid, sodium, magnesium and potassium in the desert decreased by 70%, 41%, 53%, 22% and 36%, respectively. Urinary pH decreased from 6.1 to 5.6 while in the desert, and citrate and oxalate had minimal changes. After their return from the desert, apart from a decrease of 22% in oxalate, there were no statistically significant differences from baseline. While in the desert, relative supersaturation risks of uric acid and sodium urate were increased 153% and 56%, respectively. Brushite relative supersaturation decreased 24%. After their return there was no statistical difference from baseline. Our findings suggest that the kidneys preserved water and electrolytes while the Marines were subjected to the desert environment. Despite this conservation, relative saturations indicate increased risk of stones in healthy men exposed to a desert environment with rapid resolution upon return. Copyright © 2013 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

The Badain Jaran desert: remote sensing investigations.

USGS Publications Warehouse

Walker, A.S.; Olsen, J.W.; ,

1987-01-01

Approximately half the Badain Jaran desert in the north-western Alashan Plain of northern China is a sand sea. The remainder is gravel or bedrock. The north-western border of the desert is a playa. The desert has been imaged by both Landsat and the Shuttle Imaging Radar (SIR-A). -from Authors

Use of Tritium Accelerator Mass Spectrometry for Tree Ring Analysis

PubMed Central

LOVE, ADAM H.; HUNT, JAMES R.; ROBERTS, MARK L.; SOUTHON, JOHN R.; CHIARAPPA - ZUCCA, MARINA L.; DINGLEY, KAREN H.

2010-01-01

Public concerns over the health effects associated with low-level and long-term exposure to tritium released from industrial point sources have generated the demand for better methods to evaluate historical tritium exposure levels for these communities. The cellulose of trees accurately reflects the tritium concentration in the source water and may contain the only historical record of tritium exposure. The tritium activity in the annual rings of a tree was measured using accelerator mass spectrometry to reconstruct historical annual averages of tritium exposure. Milligram-sized samples of the annual tree rings from a Tamarix located at the Nevada Test Site are used for validation of this methodology. The salt cedar was chosen since it had a single source of tritiated water that was well-characterized as it varied over time. The decay-corrected tritium activity of the water in which the salt cedar grew closely agrees with the organically bound tritium activity in its annual rings. This demonstrates that the milligram-sized samples used in tritium accelerator mass spectrometry are suited for reconstructing anthropogenic tritium levels in the environment. PMID:12144257

A review on Balanites aegyptiaca Del (desert date): phytochemical constituents, traditional uses, and pharmacological activity

PubMed Central

Chothani, Daya L.; Vaghasiya, H. U.

2011-01-01

Balanites aegyptiaca Del. (Zygophyllaceae), known as ‘desert date,’ is spiny shrub or tree up to l0 m tall, widely distributed in dry land areas of Africa and South Asia. It is traditionally used in treatment of various ailments i.e. jaundice, intestinal worm infection, wounds, malaria, syphilis, epilepsy, dysentery, constipation, diarrhea, hemorrhoid, stomach aches, asthma, and fever. It contains protein, lipid, carbohydrate, alkaloid, saponin, flavonoid, and organic acid. Present review summarizes the traditional claims, phytochemistry, and pharmacology of B. aegyptiaca Del reported in scientific literature. PMID:22096319

Variation of Desert Soil Hydraulic Properties with Pedogenic Maturity

NASA Astrophysics Data System (ADS)

Nimmo, J. R.; Perkins, K. S.; Mirus, B. B.; Schmidt, K. M.; Miller, D. M.; Stock, J. D.; Singha, K.

2006-12-01

Older alluvial desert soils exhibit greater pedogenic maturity, having more distinct desert pavements, vesicular (Av) horizons, and more pronounced stratification from processes such as illuviation and salt accumulation. These and related effects strongly influence the soil hydraulic properties. Older soils have been observed to have lower saturated hydraulic conductivity, and possibly greater capacity to retain water, but the quantitative effect of specific pedogenic features on the soil water retention or unsaturated hydraulic conductivity (K) curves is poorly known. With field infiltration/redistribution experiments on three different-aged soils developed within alluvial wash deposits in the Mojave National Preserve, we evaluated effective hydraulic properties over a scale of several m horizontally and to 1.5 m depth. We then correlated these properties with pedogenic features. The selected soils are (1) recently deposited sediments, (2) a soil of early Holocene age, and (3) a highly developed soil of late Pleistocene age. In each experiment we ponded water in a 1-m-diameter infiltration ring for 2.3 hr. For several weeks we monitored subsurface water content and matric pressure using surface electrical resistance imaging, dielectric-constant probes, heat-dissipation probes, and tensiometers. Analysis of these data using an inverse modeling technique gives the water retention and K properties needed for predictive modeling. Some properties show a consistent trend with soil age. Progressively more developed surface and near-surface features such as desert pavement and Av horizons are the likely cause of an observed consistent decline of infiltration capacity with soil age. Other properties, such as vertical flow retardation by layer contrasts, appear to have a more complicated soil-age dependence. The wash deposits display distinct depositional layering that has a retarding effect on vertical flow, an effect that may be less pronounced in the older Holocene soil

An integrated approach to salt cedar control and rehabilitation

USDA-ARS?s Scientific Manuscript database

Salt cedar (Tamarix spp.), a small tree native to Central Asia has invaded more than 4.7 million acres in the western United States. Planted in the early 1800s as an ornamental and later for windbreaks and soil stabilization, it escaped cultivation, infesting riparian and adjacent communities. Thre...

Molecular Mechanism of Pancreatic and Salivary Glands Fluid and HCO3− Secretion

PubMed Central

Lee, Min Goo; Ohana, Ehud; Park, Hyun Woo; Yang, Dongki; Muallem, Shmuel

2013-01-01

Fluid and HCO3− secretion is a vital function of all epithelia and is required for the survival of the tissue. Aberrant fluid and HCO3− secretion is associated with many epithelial diseases, such as cystic fibrosis, pancreatitis, Sjögren’s syndrome and other epithelial inflammatory and autoimmune diseases. Significant progress has been made over the last 20 years in our understanding of epithelial fluid and HCO3− secretion, in particular by secretory glands. Fluid and HCO3− secretion by secretory glands is a two step process. Acinar cells secrete isotonic fluid in which the major salt is NaCl. Subsequently, the duct modifies the volume and electrolyte composition of the fluid to absorb the Cl− and secrete HCO3−. The relative volume secreted by acinar and duct cells and modification of electrolyte composition of the secreted fluids varies among secretory glands to meet their physiological functions. In the pancreas, acinar cells secrete small amount of NaCl-rich fluid, while the duct absorbs the Cl− and secretes HCO3− and the bulk of the fluid in the pancreatic juice. Fluid secretion appears to be driven by active HCO3− secretion. In the salivary glands, acinar cells secrete the bulk of the fluid in the saliva that contains high concentrations of Na+ and Cl− and fluid secretion is mediated by active Cl− secretion. The salivary glands duct absorbs both the Na+ and Cl− and secretes K+ and HCO3−. In this review, we focus on the molecular mechanism of fluid and HCO3− secretion by the pancreas and salivary glands, to highlight the similarities of the fundamental mechanisms of acinar and duct cell functions, and point the differences to meet glands specific secretions. PMID:22298651

Ethnomycological survey of traditional usage and indigenous knowledge on desert truffles among the native Sahara Desert people of Algeria.

PubMed

Bradai, Lyès; Neffar, Souad; Amrani, Khaled; Bissati, Samia; Chenchouni, Haroun

2015-03-13

Desert truffles are edible hypogeous fungi, highly appreciated by the inhabitants of hot-desert settlements. Native Saharan people use truffles for food, promoting tourism, increasing fertility, and treatment of eye diseases and fatigue. This study consists of a cross-sectional survey focusing on the knowledge, use and ethnomycological practices of desert truffles among the native people of the Algerian Northern Sahara. The study was conducted through direct interviews with 60 truffle-hunters in the regions of Ouargla and Ghardaia. Three species were harvested and consumed by the surveyed subjects: Terfezia claveryi was the most appreciated and most expensive species, followed by Terfezia areanaria moderately preferred, then Tirmania nivea the least appreciated and least expensive. Among the 60 interviewees, 90% rely on the abundance of symbiotic plants (Helianthemum lippii) to harvest truffles, 65% begin harvesting from mid-February to March, after rains of the autumn (38%) and winter (36%), particularly in the Wadi beds (37%) and Daya landscapes (32%). Interviewees harvested truffles mainly for home consumption; however 26.7% sell any harvest surplus, and of those only 15% generate significant revenue from this source, and 73% considered the sale of desert truffles to have low financial value. Desert truffles are used in traditional medicine, especially against eye infections (22%), weakness (19%) and to promote male fertility (19%). In the case of desert truffles for consumption, the surveyed population preferred to prepare the truffles with couscous and meat, or in porridge. Respondents used price as the main criterion for deciding whether to purchase desert truffles. The surveyed trufflers use the knowledge passed from one generation to the next to help ensure a good harvest of truffles during each foray into the desert. Our findings highlight the various uses of truffles in the Sahara Desert, and how these relate to the lifestyle of local people. Copyright �

Thresholds of Detection and Identification of Halite Nodule Habitats in the Atacama Desert Using Remote Imaging

NASA Technical Reports Server (NTRS)

Phillips, M. S.; Moersch, J. E.; Cabrol, N. A.; Davila, A. F.

2018-01-01

The guiding theme of Mars exploration is shifting from global and regional habitability assessment to biosignature detection. To locate features likely to contain biosignatures, it is useful to focus on the reliable identification of specific habitats with high biosignature preservation potential. Proposed chloride deposits on Mars may represent evaporitic environments conducive to the preservation of biosignatures. Analogous chloride- bearing, salt-encrusted playas (salars) are a habitat for life in the driest parts of the Atacama Desert, and are also environments with a taphonomic window. The specific geologic features that harbor and preserve microorganisms in Atacama salars are sub- meter to meter scale salt protuberances, or halite nodules. This study focuses on the ability to recognize and map halite nodules using images acquired from an unmanned aerial vehicle (UAV) at spatial resolutions ranging from mm/pixel to that of the highest resolution orbital images available for Mars.

Microbial biosynthesis and secretion of l-malic acid and its applications.

PubMed

Chi, Zhe; Wang, Zhi-Peng; Wang, Guang-Yuan; Khan, Ibrar; Chi, Zhen-Ming

2016-01-01

l-Malic acid has many uses in food, beverage, pharmaceutical, chemical and medical industries. It can be produced by one-step fermentation, enzymatic transformation of fumaric acid to l-malate and acid hydrolysis of polymalic acid. However, the process for one-step fermentation is preferred as it has many advantages over any other process. The pathways of l-malic acid biosynthesis in microorganisms are partially clear and three metabolic pathways including non-oxidative pathway, oxidative pathway and glyoxylate cycle for the production of l-malic acid from glucose have been identified. Usually, high levels of l-malate are produced under the nitrogen starvation conditions, l-malate, as a calcium salt, is secreted from microbial cells and CaCO3 can play an important role in calcium malate biosynthesis and regulation. However, it is still unclear how it is secreted into the medium. To enhance l-malate biosynthesis and secretion by microbial cells, it is very important to study the mechanisms of l-malic acid biosynthesis and secretion at enzymatic and molecular levels.

Desert dust hazards: A global review

NASA Astrophysics Data System (ADS)

Middleton, N. J.

2017-02-01

Dust storms originate in many of the world's drylands and frequently present hazards to human society, both within the drylands themselves but also outside drylands due to long-range transport of aeolian sediments. Major sources of desert dust include the Sahara, the Middle East, central and eastern Asia, and parts of Australia, but dust-raising occurs all across the global drylands and, on occasion, beyond. Dust storms occur throughout the year and they vary in frequency and intensity over a number of timescales. Long-range transport of desert dust typically takes place along seasonal transport paths. Desert dust hazards are here reviewed according to the three phases of the wind erosion system: where dust is entrained, during the transport phase, and on deposition. This paper presents a synthesis of these hazards. It draws on empirical examples in physical geography, medical geology and geomorphology to discuss case studies from all over the world and in various fields. These include accelerated soil erosion in agricultural zones - where dust storms represent a severe form of accelerated soil erosion - the health effects of air pollution caused by desert aerosols via their physical, chemical and biological properties, transport accidents caused by poor visibility during desert dust events, and impacts on electricity generation and distribution. Given the importance of desert dust as a hazard to human societies, it is surprising to note that there have been relatively few attempts to assess their impact in economic terms. Existing studies in this regard are also reviewed, but the wide range of impacts discussed in this paper indicates that desert dust storms deserve more attention in this respect.

Multi locus sequence analysis and symbiotic characterization of novel Ensifer strains nodulating Tephrosia spp. in the Indian Thar Desert.

PubMed

Tak, Nisha; Awasthi, Esha; Bissa, Garima; Meghwal, Raju Ram; James, Euan K; Sprent, Janet S; Gehlot, Hukam S

2016-12-01

Phylogenetically diverse Ensifer strains associated with five species of Tephrosia growing in alkaline soils of semi-arid regions of the Thar Desert were characterized using multi locus sequence analysis. Based on 16S rRNA and four protein-coding housekeeping gene (recA, atpD, glnII and dnaK) sequences, the Tephrosia-Ensifer strains were genetically different from the type strains of Ensifer saheli, Ensifer kostiensis, Ensifer terangae (African origin) and Ensifer psoraleae (Asiatic origin). One strain, Ensifer sp. TL4, showed maximum similarity (99%) to Ensifer adhaerens LMG 20216 T and formed a separate lineage close to it. Phylogenetic incongruence between sym and housekeeping genes was observed. The monophyletic origin of symbiotic genes from Asia in the Tephrosia-Ensifer strains from the Thar Desert suggests that they might have been acquired from a common ancestor and horizontally transferred. These novel strains are promiscuous, cross-nodulating some papilionoid crop species, mimosoid trees and the caesalpinioid Chamaecrista pumila. This study improves understanding of the distribution of Ensifer in unexplored and threatened alkaline arid regions of the Thar Desert and how this relates to other similar regions in the world. Copyright © 2016 Elsevier GmbH. All rights reserved.

Does salt have a permissive role in the induction of puberty?

PubMed Central

Pitynski, Dori; Flynn, Francis W.; Skinner, Donal C.

2017-01-01

Puberty is starting earlier than ever before and there are serious physiological and sociological implications as a result of this development. Current research has focused on the potential role of high caloric, and commensurate high adiposity, contributions to early puberty. However, girls with normal BMI also appear to be initiating puberty earlier. Westernized diets, in addition to being high in fat and sugar, are also high in salt. To date, no research has investigated a link between elevated salt and the reproductive axis. We hypothesize that a high salt diet can result in an earlier onset of puberty through three mechanisms that are not mutually exclusive. (1) High salt activates neurokinin B, a hormone that is involved in both the reproductive axis and salt regulation, and this induces kisspeptin release and ultimate activation of the reproductive axis. (2) Vasopressin released in response to high salt acts on vasopressin receptors expressed on kisspeptin neurons in the anteroventral periventricular nucleus, thereby stimulating gonadotropin releasing hormone and subsequently luteinizing hormone secretion. (3) Salt induces metabolic changes that affect the reproductive axis. Specifically, salt acts indirectly to modulate adiposity, ties in with the obesity epidemic, and further compounds the pathologic effects of obesity. Our overall hypothesis offers an additional cause behind the induction of puberty and provides testable postulates to determine the mechanism of potential salt-mediated affects on puberty. PMID:26190310

Extensional collapse along the Sevier Desert reflection, northern Sevier Desert basin, western United States

NASA Astrophysics Data System (ADS)

Coogan, James C.; Decelles, Peter G.

1996-10-01

Newly released and previously published seismic reflection data from the northern Sevier Desert basin provide a complete seismic transect between the tilted western margin of the basin and the eastern breakaway zone. When tied to well and surface age data, the transect delineates a continuum of extensional fault and basin fill geometries that developed between late Oligocene and Pleistocene time across the basin. A minimum of 18 km of top-to-the-west normal displacement is estimated across the Sevier Desert from only the most conspicuous growth geometries and offsets across listric normal faults that sole downward into the Sevier Desert reflection (SDR). The SDR clearly marks a normal fault zone beneath the entire basin, where stratal truncations are imaged for 50% of the 39 km length of the reflection east of the Cricket Mountains block. Restoration of extensional displacement along this entire 39 km fault length is necessary to reconstruct the pre-Oligocene configuration and erosion level of Sevier thrust sheets across the Sevier Desert area. The SDR normal fault zone underlies the former topographic crest of the Sevier orogenic belt, where it accommodated extensional collapse after cessation of regional contractile tectonism.

[Water sources of Nitraria sibirica and response to precipitation in two desert habitats].

PubMed

Zhou, Hai; Zhao, Wen Zhi; He, Zhi Bin

2017-07-18

Nitraria sibirica usually exists in a form of nebkhas, and has strong ecological adaptability. The plant species has distinctive function for wind prevention and sand fixation, and resistance drought and salt. However, the water condition is still a limiting factor for the plant survival and development. In order to understand the water use strategy of the plant in different desert habitats, we selected the N. sibirica growing in sandy desert habitat and gravel desert habitat to study the seaso-nal variation of plant water sources and response to precipitation at the edge of the oasis of Linze in the Hexi Corridor. We measured the oxygen stable isotope of the plant stem water and the different potential water sources (precipitation, soil water and ground water), and used the IsoSource model to calculate the proportion of water sources from the potential water. The results showed that there were significant seasonal variation characteristics of δ 18 O value and water source of stem water for the plant in the two habitats. In the sandy habitat, the plant used more ground water in the less precipitation seasons including spring and fall, and more than 50% of the water sources absorbed from ground water. However, under the condition of gravel habitat, the plant could not achieve the ground water level depth of 11.5 m, and its water source was controlled by precipitation, which had large seasonal variability. The water sources of N. sibirica had significant responses to the change of precipitation in the two desert habitats. Following the rapid decrease of soil water content after the precipitation events, the plant in the sandy habitat turned to use the abundant ground water as the main sources of water, while the plant in the gravel habitat only used the less water from precipita-tion infiltration to the deep soil. Therefore, different water use strategies of the plant in the two habitats were the main reason for the difference in growth characteristics, and it had a

Desert Amplification in a Warming Climate

PubMed Central

Zhou, Liming

2016-01-01

Here I analyze the observed and projected surface temperature anomalies over land between 50°S-50°N for the period 1950–2099 by large-scale ecoregion and find strongest warming consistently and persistently seen over driest ecoregions such as the Sahara desert and the Arabian Peninsula during various 30-year periods, pointing to desert amplification in a warming climate. This amplification enhances linearly with the global mean greenhouse gases(GHGs) radiative forcing and is attributable primarily to a stronger GHGs-enhanced downward longwave radiation forcing reaching the surface over drier ecoregions as a consequence of a warmer and thus moister atmosphere in response to increasing GHGs. These results indicate that desert amplification may represent a fundamental pattern of global warming associated with water vapor feedbacks over land in low- and mid- latitudes where surface warming rates depend inversely on ecosystem dryness. It is likely that desert amplification might involve two types of water vapor feedbacks that maximize respectively in the tropical upper troposphere and near the surface over deserts, with both being very dry and thus extremely sensitive to changes of water vapor. PMID:27538725

Genetic transformation of Populus tomentosa to improve salt tolerance

Treesearch

Ningxia Du; Xin Liu; Yun Li; Shouyi Chen; Jinsong Zhang; Da Ha; Wenguang Deng; Chunkui Sun; Yingzhi Zhang; Paula M Pijut

2012-01-01

Soil salinity can be a limiting factor for productivity in agriculture and forestry. In order to fully utilize saline lands productively in plantation forestry for pulp production, the genetic modification of tree species for salt tolerance may be required. The AhDREB1 gene, a DREB-like transcription factor gene, was transferred into ...

Multiple Sulfate Isotopic Evidence on the Formation of Oxide Copper Ore at Spence, Atacama Desert, Northern Chile

NASA Astrophysics Data System (ADS)

Sun, T.; Bao, H.; Reich, M.; Palacios, C.

2007-12-01

In the Atacama Desert of northern Chile, one of the world's richest metallogenic provinces, porphyry copper deposits are characterized by the unique occurrence of atacamite in their oxidized zones. The origin and formation of the oxide zone of these copper deposits is, however, controversial. It was proposed that Cl-rich deep formation water pumping-up events along faults by earthquakes, after onset of the hyperaridity, were required (Cameron et al., 2007). Their model would imply that supplies of saline deep formation water from fractures to the surface should have left behind a homogeneous or fracture-controlled salt profile from surface down to the oxide zone. While no excluding the deep formation water model in other deposit, here we propose that, in our sampling region, the alternative saline source, which is critical for atacamite formation, could be locally evaporated groundwater, Cl-rich salts leached from arid surface by meteoric water, or brines from eastern salar basins at a time when the climate in northern Chile was changing from arid to hyperarid. At this climate transition, arid- requiring minerals such as atacamite in the oxide zone were formed and, more importantly, preserved upon evaporation beneath the surface alluvial deposits. Since salt accumulation at the surface remain active during hyperarid condition, our model would predict that water-soluble salt profile from surface to the oxide zone should have a characteristic pattern: salts with an atmospheric component on the surface gradually transitioning to salts of the oxide ore zone on the bottom and a mixing zone in between. To test these two alternative models, we focus on sulfate salts, one of the common water-soluble salts in arid environments. An added advantage is that sulfate accumulated on desert surface has a secondary atmospheric component that bears a unique triple oxygen isotope signature, easily distinguishable from sulfate formed by the oxidation of sulfide minerals at the oxide

How desert varnish forms?

NASA Astrophysics Data System (ADS)

Perry, Randall S.; Kolb, Vera M.; Lynne, Bridget Y.; Sephton, Mark A.; Mcloughlin, Nicola; Engel, Michael H.; Olendzenski, Lorraine; Brasier, Martin; Staley, James T., Jr.

2005-09-01

Desert varnish is a black, manganese-rich rock coating that is widespread on Earth. The mechanism underlying its formation, however, has remained unresolved. We present here new data and an associated model for how desert varnish forms, which substantively challenges previously accepted models. We tested both inorganic processes (e.g. clays and oxides cementing coatings) and microbial methods of formation. Techniques used in this preliminary study include SEM-EDAX with backscatter, HRTEM of focused ion beam prepared (FIB) wafers and several other methods including XRPD, Raman spectroscopy, XPS and Tof-SIMS. The only hypothesis capable of explaining a high water content, the presence of organic compounds, an amorphous silica phase (opal-A) and lesser quantities of clays than previously reported, is a mechanism involving the mobilization and redistribution of silica. The discovery of silica in desert varnish suggests labile organics are preserved by interaction with condensing silicic acid. Organisms are not needed for desert varnish formation but Bacteria, Archaea, Eukarya, and other organic compounds are passively incorporated and preserved as organominerals. The rock coatings thus provide useful records of past environments on Earth and possibly other planets. Additionally this model also helps to explain the origin of key varnish and rock glaze features, including their hardness, the nature of the "glue" that binds heterogeneous components together, its layered botryoidal morphology, and its slow rate of formation.

Egypt western desert activity hits high gear

DOE Office of Scientific and Technical Information (OSTI.GOV)

Petzet, G.A.

1996-11-04

Exploration in Egypt`s western desert is turning up large oil and gas reserves in several sub-basins. Though not a threat to the Gulf of Suez`s oil production dominance, the western desert`s output is climbing. And gas production is also set to rise as more pipelines are built. The paper describes the geology, Qarun field production, further exploration at Qarun and the Khalda/Obaiyed gas.

Insights into alluvial fan dynamics: Evolution of the Miocene Elephant Trees Formation, Anza Borrego Desert, CA

NASA Astrophysics Data System (ADS)

Steel, E.; Simkins, L. M.; Reynolds, L.; Fidler, M. K.

2017-12-01

The Cenozoic Fish Creek - Vallecito Basin formed through extension and transtention associated with the localization of the Pacific-North American plate boundary in the Salton Trough region of Southern California. The exhumation of this basin along the hanging wall of the West Salton Detachment Fault since 1 Ma exposed a well-preserved sedimentary sequence that records an abrupt shift from the alluvial and fluvial deposits of the Elephant Trees Formation to the marine turbidites of the Latrania Formation. This transition marks the rapid marine incursion into the Gulf of California at 6.3 Ma (Dorsey et al., 2011). The Elephant Trees Formation is, therefore, a key transitional unit for understanding environmental change during the early stages of basin formation and the initial opening of the Gulf of California. Here, we present a detailed investigation of the characteristics of the Elephant Trees Formation, including bed thickness, clast size, paleoflow indicators, sedimentary structures, and sorting to understand the changing depositional environments associated with the onset of relative plate motion in the Gulf of California - Salton Trough corridor. This study aims to answer key questions regarding both regional tectonics and the dynamics of alluvial fan progradation, including 1) Does the Elephant Trees Formation record initiation of rapid basin subsidence and basinward progradation of alluvial fans? And 2) if so, what insights can the Elephant Trees Formation provide regarding the dynamics of debris flows and alluvial fan evolution? Our results improve understanding of proximal to distal facies variations within alluvial fan deposits and further refine the paleogeography during time of deposition of the Elephant Trees Formation ( 6.3 - 8.0 Ma) leading up to the timing of rapid marine incursion.

Lessons from the Desert

DTIC Science & Technology

1993-04-14

involvement in Operations DESERT SHIELD and STORM. The 498th was a unique unit, well-suited for the gamut of operations conducted by the 2AD (FWD) during its...Division (Forward), during that unit’s involvement in Operations DESERT SHIELD and STORM. The 498th was a unique unit, well-suited for the gamut of...well-suited fir the gamut of operations conducted by 2AD (FWD) during its stay in Southwest Asia (SWA) . I commanded the 498th Support Battalion from

Geometeorological data collected by the USGS Desert Winds Project at Gold Spring, Great Basin desert, northeastern Arizona, 1979-1992

USGS Publications Warehouse

Helm, P.J.; Breed, C.S.; Tigges, R.K.; Garcia, P.A.

1995-01-01

The primary purpose of the Desert Winds Project (DWP) is to obtain high-resolution meteorological data and related surface geological and vegetation data for natural (e.g., uncultivated) desert sites where wind is or has been a major erosive or depositional force. The objectives are twofold: (1) to provide the detailed field measurements needed to carry out quantitative studies of wind as an agent of surface geologic change; and (2) to establish a baseline for defining the 'normal' range of climatic conditions that can be expected to occur on a decadal time scale, in areas considered representative of the major American deserts. The Gold Spring locality was selected to represent that part of the Great Basin Desert that extends into northeastern Arizona. The long-term goal for acquiring and analyzing the Desert Winds Project data is to use them to address problems of land resource degradation by wind, whether resulting from climatic variation aridification) or human activities (desertification), or both (see techinfo.doc).

Late Quaternary history of the Atacama Desert

USGS Publications Warehouse

Latorre, Claudio; Betancourt, Julio L.; Rech, Jason A.; Quade, Jay; Holmgren, Camille; Placzek, Christa; Maldonado, Antonio; Vuille, Mathias; Rylander, Kate A.; Smith, Mike; Hesse, Paul

2005-01-01

Of the major subtropical deserts found in the Southern Hemisphere, the Atacama Desert is the driest. Throughout the Quaternary, the most pervasive climatic influence on the desert has been millennial-scale changes in the frequency and seasonality of the scant rainfall, and associated shifts in plant and animal distributions with elevation along the eastern margin of the desert. Over the past six years, we have mapped modern vegetation gradients and developed a number of palaeoenvironmental records, including vegetation histories from fossil rodent middens, groundwater levels from wetland (spring) deposits, and lake levels from shoreline evidence, along a 1200-kilometre transect (16–26°S) in the Atacama Desert. A strength of this palaeoclimate transect has been the ability to apply the same methodologies across broad elevational, latitudinal, climatic, vegetation and hydrological gradients. We are using this transect to reconstruct the histories of key components of the South American tropical (summer) and extratropical (winter) rainfall belts, precisely at those elevations where average annual rainfall wanes to zero. The focus has been on the transition from sparse, shrubby vegetation (known as the prepuna) into absolute desert, an expansive hyperarid terrain that extends from just above the coastal fog zone (approximately 800 metres) to more than 3500 metres in the most arid sectors in the southern Atacama.

High-Salt Diet Has a Certain Impact on Protein Digestion and Gut Microbiota: A Sequencing and Proteome Combined Study.

PubMed

Wang, Chao; Huang, Zixin; Yu, Kequan; Ding, Ruiling; Ye, Keping; Dai, Chen; Xu, Xinglian; Zhou, Guanghong; Li, Chunbao

2017-01-01

High-salt diet has been considered to cause health problems, but it is still less known how high-salt diet affects gut microbiota, protein digestion, and passage in the digestive tract. In this study, C57BL/6J mice were fed low- or high-salt diets (0.25 vs. 3.15% NaCl) for 8 weeks, and then gut contents and feces were collected. Fecal microbiota was identified by sequencing the V4 region of 16S ribosomal RNA gene. Proteins and digested products of duodenal, jejunal, cecal, and colonic contents were identified by LC-MS-MS. The results indicated that the high-salt diet increased Firmicutes/Bacteroidetes ratio, the abundances of genera Lachnospiraceae and Ruminococcus ( P < 0.05), but decreased the abundance of Lactobacillus ( P < 0.05). LC-MS-MS revealed a dynamic change of proteins from the diet, host, and gut microbiota alongside the digestive tract. For dietary proteins, high-salt diet seemed not influence its protein digestion and absorption. For host proteins, 20 proteins of lower abundance were identified in the high-salt diet group in duodenal contents, which were involved in digestive enzymes and pancreatic secretion. However, no significant differentially expressed proteins were detected in jejunal, cecal, and colonic contents. For bacterial proteins, proteins secreted by gut microbiota were involved in energy metabolism, sodium transport, and protein folding. Five proteins (cytidylate kinase, trigger factor, 6-phosphogluconate dehydrogenase, transporter, and undecaprenyl-diphosphatase) had a higher abundance in the high-salt diet group than those in the low-salt group, while two proteins (acetylglutamate kinase and PBSX phage manganese-containing catalase) were over-expressed in the low-salt diet group than in the high-salt group. Consequently, high-salt diet may alter the composition of gut microbiota and has a certain impact on protein digestion.

High-Salt Diet Has a Certain Impact on Protein Digestion and Gut Microbiota: A Sequencing and Proteome Combined Study

PubMed Central

Wang, Chao; Huang, Zixin; Yu, Kequan; Ding, Ruiling; Ye, Keping; Dai, Chen; Xu, Xinglian; Zhou, Guanghong; Li, Chunbao

2017-01-01

High-salt diet has been considered to cause health problems, but it is still less known how high-salt diet affects gut microbiota, protein digestion, and passage in the digestive tract. In this study, C57BL/6J mice were fed low- or high-salt diets (0.25 vs. 3.15% NaCl) for 8 weeks, and then gut contents and feces were collected. Fecal microbiota was identified by sequencing the V4 region of 16S ribosomal RNA gene. Proteins and digested products of duodenal, jejunal, cecal, and colonic contents were identified by LC-MS-MS. The results indicated that the high-salt diet increased Firmicutes/Bacteroidetes ratio, the abundances of genera Lachnospiraceae and Ruminococcus (P < 0.05), but decreased the abundance of Lactobacillus (P < 0.05). LC-MS-MS revealed a dynamic change of proteins from the diet, host, and gut microbiota alongside the digestive tract. For dietary proteins, high-salt diet seemed not influence its protein digestion and absorption. For host proteins, 20 proteins of lower abundance were identified in the high-salt diet group in duodenal contents, which were involved in digestive enzymes and pancreatic secretion. However, no significant differentially expressed proteins were detected in jejunal, cecal, and colonic contents. For bacterial proteins, proteins secreted by gut microbiota were involved in energy metabolism, sodium transport, and protein folding. Five proteins (cytidylate kinase, trigger factor, 6-phosphogluconate dehydrogenase, transporter, and undecaprenyl-diphosphatase) had a higher abundance in the high-salt diet group than those in the low-salt group, while two proteins (acetylglutamate kinase and PBSX phage manganese-containing catalase) were over-expressed in the low-salt diet group than in the high-salt group. Consequently, high-salt diet may alter the composition of gut microbiota and has a certain impact on protein digestion. PMID:29033907

Phytoremediation for Oily Desert Soils

NASA Astrophysics Data System (ADS)

Radwan, Samir

This chapter deals with strategies for cleaning oily desert soils through rhizosphere technology. Bioremediation involves two major approaches; seeding with suitable microorganisms and fertilization with microbial growth enhancing materials. Raising suitable crops in oil-polluted desert soils fulfills both objectives. The rhizosphere of many legume and non-legume plants is richer in oil-utilizing micro-organisms than non-vegetated soils. Furthermore, these rhizospheres also harbour symbiotic and asymbiotic nitrogen-fixing bacteria, and are rich in simple organic compounds exuded by plant roots. Those exudates are excellent nutrients for oil-utilizing microorganisms. Since many rhizospheric bacteria have the combined activities of hydrocarbon-utilization and nitrogen fixation, phytoremediation provides a feasible and environmentally friendly biotechnology for cleaning oil-polluted soils, especially nitrogen-poor desert soils.

Microspatial ecotone dynamics at a shifting range limit: plant-soil variation across salt marsh-mangrove interfaces.

PubMed

Yando, E S; Osland, M J; Hester, M W

2018-05-01

Ecotone dynamics and shifting range limits can be used to advance our understanding of the ecological implications of future range expansions in response to climate change. In the northern Gulf of Mexico, the salt marsh-mangrove ecotone is an area where range limits and ecotone dynamics can be studied in tandem as recent decreases in winter temperature extremes have allowed for mangrove expansion at the expense of salt marsh. In this study, we assessed aboveground and belowground plant-soil dynamics across the salt marsh-mangrove ecotone quantifying micro-spatial patterns in horizontal extent. Specifically, we studied vegetation and rooting dynamics of large and small trees, the impact of salt marshes (e.g. species and structure) on mangroves, and the influence of vegetation on soil properties along transects from underneath the mangrove canopy into the surrounding salt marsh. Vegetation and rooting dynamics differed in horizontal reach, and there was a positive relationship between mangrove tree height and rooting extent. We found that the horizontal expansion of mangrove roots into salt marsh extended up to eight meters beyond the aboveground boundary. Variation in vegetation structure and local hydrology appear to control mangrove seedling dynamics. Finally, soil carbon density and organic matter did not differ within locations across the salt marsh-mangrove interface. By studying aboveground and belowground variation across the ecotone, we can better predict the ecological effects of continued range expansion in response to climate change.

Microspatial ecotone dynamics at a shifting range limit: plant–soil variation across salt marsh–mangrove interfaces

USGS Publications Warehouse

Yando, Erik S.; Osland, Michael J.; Hester, Mark H.

2018-01-01

Ecotone dynamics and shifting range limits can be used to advance our understanding of the ecological implications of future range expansions in response to climate change. In the northern Gulf of Mexico, the salt marsh–mangrove ecotone is an area where range limits and ecotone dynamics can be studied in tandem as recent decreases in winter temperature extremes have allowed for mangrove expansion at the expense of salt marsh. In this study, we assessed aboveground and belowground plant–soil dynamics across the salt marsh–mangrove ecotone quantifying micro-spatial patterns in horizontal extent. Specifically, we studied vegetation and rooting dynamics of large and small trees, the impact of salt marshes (e.g. species and structure) on mangroves, and the influence of vegetation on soil properties along transects from underneath the mangrove canopy into the surrounding salt marsh. Vegetation and rooting dynamics differed in horizontal reach, and there was a positive relationship between mangrove tree height and rooting extent. We found that the horizontal expansion of mangrove roots into salt marsh extended up to eight meters beyond the aboveground boundary. Variation in vegetation structure and local hydrology appear to control mangrove seedling dynamics. Finally, soil carbon density and organic matter did not differ within locations across the salt marsh-mangrove interface. By studying aboveground and belowground variation across the ecotone, we can better predict the ecological effects of continued range expansion in response to climate change.

Roles of saltcedar (Tamarix spp.) and capillary rise in salinizing a non-flooding terrace on a flow-regulated desert river

USGS Publications Warehouse

Glenn, E.P.; Morino, K.; Nagler, P.L.; Murray, R.S.; Pearlstein, S.; Hultine, K.R.

2012-01-01

Tamarix spp. (saltcedar) secretes salts and has been considered to be a major factor contributing to the salinization of river terraces in western US riparian zones. However, salinization can also occur from the capillary rise of salts from the aquifer into the vadose zone. We investigated the roles of saltcedar and physical factors in salinizing the soil profile of a non-flooding terrace at sites on the Cibola National Wildlife Refuge on the Lower Colorado River, USA. We placed salt traps under and between saltcedar shrubs and estimated the annual deposition rate of salts from saltcedar. These were then compared to the quantities and distribution on of salts in the soil profile. Dense stands of saltcedar deposited 0.159kgm -2yr -1 of salts to the soil surface. If this rate was constant since seasonal flooding ceased in 1938 and all of the salts were retained in the soil profile, they could account for 11.4kgm -2 of salt, about 30% of total salts in the profile today. Eliminating saltcedar would not necessarily reduce salts, because vegetation reduces the upward migration of salts in bulk flow from the aquifer. The densest saltcedar stand had the lowest salt levels in the vadose zone in this study. ?? 2011 Elsevier Ltd.

Desert and groundwater dynamics of the Jurassic Navajo Sandstone, southeast Utah

NASA Astrophysics Data System (ADS)

Chan, M. A.; Hasiotis, S. T.; Parrish, J. T.

2017-12-01

The Jurassic Navajo Sandstone of southeastern Utah is a rich archive of a desert complex with an active groundwater system, influenced by climate changes and recharge from the Uncompahgre Uplift of the Ancestral Rocky Mountains. This eastern erg margin was dominated by dune deposits of large (>10 m thick) and small (m-scale) crossbedded sandstone sets. Within these porous deposits, common soft sediment deformation is expressed as contorted and upturned bedding, fluid escape structures, concentrations of clastic pipes with ring faults, and thick intervals of massive sandstone embedded in crossbedded sandstone. Collectively, these deformation features reflect changes and/or overpressure in the groundwater system. Interdune deposits record laterally variable bounding surfaces, resulting from the change in position of and proximity to the water table. Interdune modification by pedogenesis from burrows, roots, and trees suggest stable periods of moisture and water supply, as well as periodic drying expressed as polygonal cracked mud- to sand-cracked layers. Freshwater bedded and platy limestone beds represent lakes of decameter to kilometer extent, common in the upper part of the formation. Some carbonate springs that fed the lakes are preserved as limestone buildups (tufa mounds) with microbial structures. Extradunal deposits of rivers to small ephemeral streams show channelized and lenticular, subhorizontal, cm- to m-scale sandstone bodies with basal scours and rip-up clasts. Proxy records of the active hydrology imply a changing landscape at the Navajo desert's edge, punctuated by periods of significant rainfall, runoff, rivers, lakes, and springs, fed by high water table conditions to sustain periods of flourishing communities of plants, arthropods, reptiles, mammals, and dinosaurs. Strong ground motion perturbations periodically disrupted porous, water-saturated sands with possible surface eruptions, adding to the dynamic activity of the desert regime.

Origin of desert loess from some experimental observations

NASA Technical Reports Server (NTRS)

Whalley, W. B.; Smith, B. J.; Marshall, J. R.

1982-01-01

The aeolian attrition of angular quartz grains previously produced by weathering in deserts has been simulated, yielding abrasion products which show that both coarse and fine silt sizes are produced by this process. These results suggest that desert aeolian processes can produce loess, and it is speculated that while much of this material from many deserts has been deposited in the sea, the Chinese loess could have been produced in the Gobi desert. The finest of the particles produced by such attrition may serve as a source of silica for silcrete formation.

Gopherus agassizii (Desert Tortoise). Non-native seed dispersal

USGS Publications Warehouse

Ennen, J.R.; Loughran, Caleb L.; Lovich, Jeffrey E.

2011-01-01

Sahara Mustard (Brassica tournefortii) is a non-native, highly invasive weed species of southwestern U.S. deserts. Sahara Mustard is a hardy species, which flourishes under many conditions including drought and in both disturbed and undisturbed habitats (West and Nabhan 2002. In B. Tellman [ed.], Invasive Plants: Their Occurrence and Possible Impact on the Central Gulf Coast of Sonora and the Midriff Islands in the Sea of Cortes, pp. 91–111. University of Arizona Press, Tucson). Because of this species’ ability to thrive in these habitats, B. tournefortii has been able to propagate throughout the southwestern United States establishing itself in the Mojave and Sonoran Deserts in Arizona, California, Nevada, and Utah. Unfortunately, naturally disturbed areas created by native species, such as the Desert Tortoise (Gopherus agassizii), within these deserts could have facilitated the propagation of B. tournefortii. (Lovich 1998. In R. G. Westbrooks [ed.], Invasive Plants, Changing the Landscape of America: Fact Book, p. 77. Federal Interagency Committee for the Management of Noxious and Exotic Weeds [FICMNEW], Washington, DC). However, Desert Tortoises have never been directly observed dispersing Sahara Mustard seeds. Here we present observations of two Desert Tortoises dispersing Sahara Mustard seeds at the interface between the Mojave and Sonoran deserts in California.

Food deserts and nutritional risk in Paraguay.

PubMed

Gartin, Meredith

2012-01-01

The purpose of this case study in San Lorenzo, Paraguay is to identify a food desert in a developing context and to test if food deserts shape residential obesity risk. This article reviews some of the debate surrounding whether food deserts really exist; and, if so, what are the dietary implications of living in a food desert. The research is an exploratory/explanatory design. The author mapped the downtown food retail district and the neighborhood food environment to identify what stores/markets. The author assessed each type of food store using an adapted version of the Nutrition Environment Measure Survey for Stores (NEMS-S) for Paraguay. Body mass index and household characteristics were collected with 68 households in a small neighborhood; and, the author matched the NEMS-S scores to the store reported by households as their primary grocery store for regression tests. The results suggest that a tradeoff exists in the local food environment between food stores which negatively impact obesity risk for local residents. Exposure to this tradeoff appears to worsen as people live longer in the food desert. Thus, the results support the location of a food desert finding in Paraguay. The underlying factors of a food desert extend beyond food access to focus on the issues of justice. A way to improve upon future research to build scholarship on the relationship between deprivation and obesity requires that sample sizes are either large or representative of the population and that the research should be based on multiple neighborhood and city sites. Copyright © 2012 Wiley Periodicals, Inc.

Life span and structure of ephemeral root modules of different functional groups from a desert system.

PubMed

Liu, Bo; He, Junxia; Zeng, Fanjiang; Lei, Jiaqiang; Arndt, Stefan K

2016-07-01

The terminal branch orders of plant root systems have been proposed as short-lived 'ephemeral' modules specialized for resource absorption. The occurrence of ephemeral root modules has so far only been reported for a temperate tree species and it is unclear if the concept also applies to other woody (shrub, tree) and herb species. Fine roots of 12 perennial dicotyledonous herb, shrub and tree species were monitored for two growing seasons using a branch-order classification, sequential sampling and rhizotrons in the Taklamakan desert. Two root modules existed in all three plant functional groups. Among the first five branch orders, the first two (perennial herbs, shrubs) or three (trees) root orders were ephemeral and had a primary anatomical structure, high nitrogen (N) concentrations, high respiration rates and very short life spans of 1-4 months, whereas the last two branch orders in all functional groups were perennial, with thicker diameters, no or collapsed cortex, distinct secondary growth, low N concentrations, low respiration rates, but much longer life spans. Ephemeral, short-lived root modules and long-lived, persistent root modules seem to be a general feature across many plant functional groups and could represent a basic root system design. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

Comparative phylogeography reveals deep lineages and regional evolutionary hotspots in the Mojave and Sonoran Deserts

USGS Publications Warehouse

Wood, Dustin A.; Vandergast, Amy G.; Barr, Kelly R.; Inman, Richard D.; Esque, Todd C.; Nussear, Kenneth E.; Fisher, Robert N.

2013-01-01

Aim: We explored lineage diversification within desert-dwelling fauna. Our goals were (1) to determine whether phylogenetic lineages and population expansions were consistent with younger Pleistocene climate fluctuation hypotheses or much older events predicted by pre-Pleistocene vicariance hypotheses, (2) to assess concordance in spatial patterns of genetic divergence and diversity among species and (3) to identify regional evolutionary hotspots of divergence and diversity and assess their conservation status. Location: Mojave, Colorado, and Sonoran Deserts, USA. Methods: We analysed previously published gene sequence data for twelve species. We used Bayesian gene tree methods to estimate lineages and divergence times. Within each lineage, we tested for population expansion and age of expansion using coalescent approaches. We mapped interpopulation genetic divergence and intra-population genetic diversity in a GIS to identify hotspots of highest genetic divergence and diversity and to assess whether protected lands overlapped with evolutionary hotspots. Results: In seven of the 12 species, lineage divergence substantially predated the Pleistocene. Historical population expansion was found in eight species, but expansion events postdated the Last Glacial Maximum (LGM) in only four. For all species assessed, six hotspots of high genetic divergence and diversity were concentrated in the Colorado Desert, along the Colorado River and in the Mojave/Sonoran ecotone. At least some proportion of the land within each recovered hotspot was categorized as protected, yet four of the six also overlapped with major areas of human development. Main conclusions: Most of the species studied here diversified into distinct Mojave and Sonoran lineages prior to the LGM – supporting older diversification hypotheses. Several evolutionary hotspots were recovered but are not strategically paired with areas of protected land. Long-term preservation of species-level biodiversity would

Fog water chemistry in the Namib desert, Namibia

NASA Astrophysics Data System (ADS)

Eckardt, Frank D.; Schemenauer, Robert S.

This study documents the ion concentrations and ion enrichment relative to sea water, in Namib Desert fog water, with the purpose of establishing its suitability for future fogwater collection schemes, while also examining claims that Namib Desert fog water carries exceptionally high concentrations of sulphate, which may be responsible for the formation of gypsum deposits in the desert. The work suggests that Namibian fog water is at least as clean as has been reported from other coastal deserts in South America and Arabia, and provides a source of very clean water for the coastal desert region of south-western Africa. It does not appear that fog is an efficient sulphur source for the formation of the gypsum deposits, unless rare events with high concentrations of marine sulphur compounds occur.

Possible Role of Pectin-containing Mucilage and Dew in Repairing Embryo DNA of Seeds Adapted to Desert Conditions

PubMed Central

Huang, Zhenying; Boubriak, Ivan; Osborne, Daphne J.; Dong, Ming; Gutterman, Yitzchak

2008-01-01

Background and Aims Repair of damage to DNA of seed embryos sustained during long periods of quiescence under dry desert conditions is important for subsequent germination. The possibility that repair of embryo DNA can be facilitated by small amounts of water derived from dew temporarily captured at night by pectinaceous surface pellicles was tested. These pellicles are secreted during early seed development and form mucilage when hydrated. Methods Seeds of Artemisia sphaerocephala and Artemisia ordosica were collected from a sandy desert. Their embryos were damaged by gamma radiation to induce a standard level of DNA damage. The treated seeds were then exposed to nocturnal dew deposition on the surface of soil in the Negev desert highlands. The pellicles were removed from some seeds and left intact on others to test the ability of mucilage to support repair of the damaged DNA when night-time humidity and temperature favoured dew formation. Repair was assessed from fragmentation patterns of extracted DNA on agarose gels. Key Results For A. sphaerocephala, which has thick seed pellicles, DNA repair occurred in seeds with intact pellicles after 50 min of cumulative night dew formation, but not in seeds from which the pellicles had been removed. For A. ordosica, which has thin seed pellicles, DNA repair took at least 510 min of cumulative night dewing to achieve partial recovery of DNA integrity. The mucilage has the ability to rehydrate after daytime dehydration. Conclusions The ability of seeds to develop a mucilaginous layer when wetted by night-time dew, and to repair their DNA under these conditions, appear to be mechanisms that help maintain seed viability under harsh desert conditions. PMID:17495979

Possible role of pectin-containing mucilage and dew in repairing embryo DNA of seeds adapted to desert conditions.

PubMed

Huang, Zhenying; Boubriak, Ivan; Osborne, Daphne J; Dong, Ming; Gutterman, Yitzchak

2008-01-01

Repair of damage to DNA of seed embryos sustained during long periods of quiescence under dry desert conditions is important for subsequent germination. The possibility that repair of embryo DNA can be facilitated by small amounts of water derived from dew temporarily captured at night by pectinaceous surface pellicles was tested. These pellicles are secreted during early seed development and form mucilage when hydrated. Seeds of Artemisia sphaerocephala and Artemisia ordosica were collected from a sandy desert. Their embryos were damaged by gamma radiation to induce a standard level of DNA damage. The treated seeds were then exposed to nocturnal dew deposition on the surface of soil in the Negev desert highlands. The pellicles were removed from some seeds and left intact on others to test the ability of mucilage to support repair of the damaged DNA when night-time humidity and temperature favoured dew formation. Repair was assessed from fragmentation patterns of extracted DNA on agarose gels. For A. sphaerocephala, which has thick seed pellicles, DNA repair occurred in seeds with intact pellicles after 50 min of cumulative night dew formation, but not in seeds from which the pellicles had been removed. For A. ordosica, which has thin seed pellicles, DNA repair took at least 510 min of cumulative night dewing to achieve partial recovery of DNA integrity. The mucilage has the ability to rehydrate after daytime dehydration. The ability of seeds to develop a mucilaginous layer when wetted by night-time dew, and to repair their DNA under these conditions, appear to be mechanisms that help maintain seed viability under harsh desert conditions.

Impact of Photovoltaic Canopy Shade on Outdoor Thermal Comfort in a Hot Desert City

NASA Astrophysics Data System (ADS)

Middel, Ariane; Selover, Nancy; Hagen, Björn; Chhetri, Nalini

2016-04-01

Shade plays an important role in designing pedestrian-friendly outdoor spaces in hot desert cities. This study investigates the impact of photovoltaic canopy shade on thermal comfort through microclimate observations and field surveys at a pedestrian mall on Arizona State University's Tempe campus. Six stationary sensors under solar canopies and in nearby sun-exposed and tree-shaded locations monitored 5-min temperature and humidity for a year. On selected clear calm days representative of each season, we conducted hourly microclimate transects from 7:00AM to 6:00PM and surveyed 1284 people about their thermal perception, comfort, and preferences. Shade lowered thermal sensation votes by approximately 1 point on the Likert scale, increasing thermal comfort in all seasons except winter. The shade type (tree or solar canopy) did not significantly impact perceived comfort, suggesting that artificial and natural shade are equally efficient in semi-arid desert environments. Globe temperature explained 50% of the variance in thermal sensation votes and was the only statistically significant meteorological predictor. Important non-meteorological factors include adaptation level, gender, thermal comfort vote, thermal preference, season, and time of day. A regression of perceived comfort on Physiological Equivalent Temperature yielded a neutral temperature of 28.6°C. The acceptable comfort range was 19.1°C-38.1°C with a preferred temperature of 20.8°C. Respondents exposed to above neutral temperatures felt more comfortable if they had been in air-conditioning 5 minutes prior to the survey, indicating a lagged response to outdoor conditions. Our study highlights the importance of active solar access management in hot urban areas.

Expression of and secretion through the Aeromonas salmonicida type III secretion system.

PubMed

Ebanks, Roger O; Knickle, Leah C; Goguen, Michel; Boyd, Jessica M; Pinto, Devanand M; Reith, Michael; Ross, Neil W

2006-05-01

Aeromonas salmonicida subsp. salmonicida is the aetiological agent of furunculosis, a disease of farmed and wild salmonids. The type III secretion system (TTSS) is one of the primary virulence factors in A. salmonicida. Using a combination of differential proteomic analysis and reverse transcriptase (RT)-PCR, it is shown that A. salmonicida A449 induces the expression of TTSS proteins at 28 degrees C, but not at its more natural growth temperature of 17 degrees C. More modest increases in expression occur at 24 degrees C. This temperature-induced up-regulation of the TTSS in A. salmonicida A449 occurs within 30 min of a growth temperature increase from 16 to 28 degrees C. Growth conditions such as low-iron, low pH, low calcium, growth within the peritoneal cavity of salmon and growth to high cell densities do not induce the expression of the TTSS in A. salmonicida A449. The only other known growth condition that induces expression of the TTSS is growth of the bacterium at 16 degrees C in salt concentrations ranging from 0.19 to 0.38 M NaCl. It is also shown that growth at 28 degrees C followed by exposure to low calcium results in the secretion of one of the TTSS effector proteins. This study presents a simple in vitro model for the expression of TTSS proteins in A. salmonicida.

Sapflow and water use of freshwater wetland trees exposed to saltwater incursion in a tidally influenced South Carolina watershed

USGS Publications Warehouse

Krauss, K.W.; Duberstein, J.A.

2010-01-01

Sea-level rise and anthropogenic activity promote salinity incursion into many tidal freshwater forested wetlands. Interestingly, individual trees can persist for decades after salt impact. To understand why, we documented sapflow (Js), reduction in Js with sapwood depth, and water use (F) of baldcypress (Taxodium distichum (L.) Rich.) trees undergoing exposure to salinity. The mean Js of individual trees was reduced by 2.8 g H2O??m-2??s-1 (or by 18%) in the outer sapwood on a saline site versus a freshwater site; however, the smallest trees, present only on the saline site, also registered the lowest Js. Hence, tree size significantly influenced the overall site effect on Js. Trees undergoing perennial exposure to salt used greater relative amounts of water in outer sapwood than in inner sapwood depths, which identifies a potentially different strategy for baldcypress trees coping with saline site conditions over decades. Overall, individual trees used 100 kg H2O??day-1 on a site that remained relatively fresh versus 23.9 kg H2O??day-1 on the saline site. We surmise that perennial salinization of coastal freshwater forests forces shifts in individual-tree osmotic balance and water-use strategy to extend survival time on suboptimal sites, which further influences growth and morphology.

Off-Road and the Fragile Desert

ERIC Educational Resources Information Center

Stebbins, Robert C.

1974-01-01

Part one of a two-part article sets forth the dimensions and the political-cultural aspects of the use of off-road vehicles in desert areas. Presents arguments for and against off-road vehicle use on national-resource land as exemplified in the California Desert. (Editor/JR)

Desert Experimental Range: Annotated bibliography

Treesearch

E. Durant McArthur; Stanley G. Kitchen

2013-01-01

Entries qualify for inclusion if they were conducted in whole or part at the Desert Experimental Range (DER, also known as the Desert Range Experiment Station) or were based on DER research in whole or part. They do not qualify merely by the author having worked at the DER when the research was performed or prepared. Entries were drawn from the original abstracts or...

Fungal diversity in the Atacama Desert.

PubMed

Santiago, Iara F; Gonçalves, Vívian N; Gómez-Silva, Benito; Galetovic, Alexandra; Rosa, Luiz H

2018-03-07

Fungi are generally easily dispersed, able to colonise a wide variety of substrata and can tolerate diverse environmental conditions. However, despite these abilities, the diversity of fungi in the Atacama Desert is practically unknown. Most of the resident fungi in desert regions are ubiquitous. Some of them, however, seem to display specific adaptations that enable them to survive under the variety of extreme conditions of these regions, such as high temperature, low availability of water, osmotic stress, desiccation, low availability of nutrients, and exposure to high levels of UV radiation. For these reasons, fungal communities living in the Atacama Desert represent an unknown part of global fungal diversity and, consequently, may be source of new species that could be potential sources for new biotechnological products. In this review, we focus on the current knowledge of the diversity, ecology, adaptive strategies, and biotechnological potential of the fungi reported in the different ecosystems of the Atacama Desert.

Nationwide desert highway assessment: a case study in China.

PubMed

Mao, Xuesong; Wang, Fuchun; Wang, Binggang

2011-07-01

The natural environment affects the construction of desert highways. Conversely, highway construction affects the natural environment and puts the ecological environment at a disadvantage. To satisfy the variety and hierarchy of desert highway construction and discover the spatio-temporal distribution of the natural environment and its effect on highway construction engineering, an assessment of the natural regional divisions of desert highways in China is carried out for the first time. Based on the general principles and method for the natural region division, the principles, method and index system for desert highway assessment is put forward by combining the desert highway construction features and the azonal differentiation law. The index system combines the dominant indicator and four auxiliary indicators. The dominant indicator is defined by the desert's comprehensive state index and the auxiliary indicators include the sand dune height, the blown sand strength, the vegetation coverage ratio and the annual average temperature difference. First the region is divided according to the dominant indicator. Then the region boundaries are amended according to the four auxiliary indicators. Finally the natural region division map for desert highway assessment is presented. The Chinese desert highways can be divided into three sections: the east medium effect region, the middle medium-severe effect region, and the west slight-medium effect region. The natural region division map effectively paves the way for the route planning, design, construction, maintenance and ongoing management of desert highways, and further helps environmental protection.

Phenological synchrony of bird migration with tree flowering at desert riparian stopover sites

USGS Publications Warehouse

Kellermann, Jherime L.; van Riper, Charles

2015-01-01

Small-bodied songbirds replenish fat reserves during migration at stopover sites where they continually encounter novel and often unpredictable environmental conditions. The ability to select and utilize high quality habitats is critical to survival and fitness. Vegetation phenology is closely linked with emergence of insect prey and may provide valid cues of food availability for stopover habitat selection. Climate change is disrupting phenological synchrony across trophic levels with negative impacts on bird populations. However, whether synchrony or mismatch indicates historic or disrupted systems remains unclear. Many Neotropical migratory songbirds of western North America must cross arid regions where drought conditions related to climate change and human water use are expected to increase. We studied migrant abundance and the diversity (niche breadth) and proportional use of vegetation species as foraging substrates and their synchrony with vegetation flowering during spring migration along the lower Colorado River in the Sonoran Desert of the U.S. and Mexico.

Negev: Land, Water, and Life in a Desert Environment

NASA Astrophysics Data System (ADS)

Back, William

In view of the continuing increased concern about the extreme fragility of deserts and desert margins, Negev provides a timely discussion of land-use practices compatible with the often conflicting goals of preservation and development. The success o f agricultural and hydrologic experiments in the Negev desert of Israel offers hope to the large percentage of the world's population that lives with an unacceptably low quality of life in desert margins. Deserts are the one remaining type of open space that, with proper use, has the potential for alleviating the misery often associated with expanding population.In addition to the science in the book, the author repeatedly reinforces the concept that “western civilization is inextricably bound to the Negev and its environs, from which it has drawn, via its desert-born religions—Judasium, Christianity, and Islam—many of the mores and concepts, and much of the imagery and love of the desert, including man's relation to nature and to ‘God’.” Deserts often are erroneously perceived to be areas of no water: In reality, these are areas in which a little rainfall occurs sporadically and unpredictably over time. This meager water supply can be meticulously garnered to produce nutritious crops and forage.

Zebra stripes in the Atacama Desert: Fossil evidence of overland flow

NASA Astrophysics Data System (ADS)

Owen, Justine J.; Dietrich, William E.; Nishiizumi, Kuni; Chong, Guillermo; Amundson, Ronald

2013-01-01

Some hillslopes in the hyperarid region of the Atacama Desert in northern Chile have surface clasts organized into distinct, contour-parallel bands separated by bare soil. We call the bands "zebra stripes" due to the contrast between the darkly varnished clasts and the light-colored, salt-rich soil. Gravel that comprises the zebra stripes is sorted such that the coarsest clasts are at the downslope front and fine progressively upslope. How and when the zebra stripes formed are perplexing questions, particularly in a region experiencing prolonged hyperaridity. Using GoogleEarth, satellite imagery, and field observations, we report the first quantitative and qualitative observations of zebra stripes in order to test hypotheses of the mechanisms and timing of their formation. We consider soil shrink-swell, seismic shaking, and overland flow as possible formation mechanisms, and find that overland flow is the most likely. Based on cosmogenic 10Be concentrations in surface clasts, salt deposition rates from the atmosphere, and content in the soils, we propose that the salt-rich soils began accumulating ~ 106 y ago and the zebra stripes formed 103-104 y at the latest. The zebra stripe pattern has been preserved due to the self-stabilization of the clasts within the stripes and the continued absence of life (which would disturb the surface, as seen at a wetter site to the south). We conclude that the occurrence of zebra stripes is diagnostic of a set of distinct characteristics of local and/or regional precipitation, soil, hillslope form, and bedrock type.

Does salt have a permissive role in the induction of puberty?

PubMed

Pitynski, Dori; Flynn, Francis W; Skinner, Donal C

2015-10-01

Puberty is starting earlier than ever before and there are serious physiological and sociological implications as a result of this development. Current research has focused on the potential role of high caloric, and commensurate high adiposity, contributions to early puberty. However, girls with normal BMI also appear to be initiating puberty earlier. Westernized diets, in addition to being high in fat and sugar, are also high in salt. To date, no research has investigated a link between elevated salt and the reproductive axis. We hypothesize that a high salt diet can result in an earlier onset of puberty through three mechanisms that are not mutually exclusive. (1) High salt activates neurokinin B, a hormone that is involved in both the reproductive axis and salt regulation, and this induces kisspeptin release and ultimate activation of the reproductive axis. (2) Vasopressin released in response to high salt acts on vasopressin receptors expressed on kisspeptin neurons in the anteroventral periventricular nucleus, thereby stimulating gonadotropin releasing hormone and subsequently luteinizing hormone secretion. (3) Salt induces metabolic changes that affect the reproductive axis. Specifically, salt acts indirectly to modulate adiposity, ties in with the obesity epidemic, and further compounds the pathologic effects of obesity. Our overall hypothesis offers an additional cause behind the induction of puberty and provides testable postulates to determine the mechanism of potential salt-mediated affects on puberty. Copyright © 2015. Published by Elsevier Ltd.

Characterization of Morphology, Volatile Profiles, and Molecular Markers in Edible Desert Truffles from the Negev Desert.

PubMed

Kamle, Madhu; Bar, Einat; Lewinsohn, Dalia; Shavit, Elinoar; Roth-Bejerano, Nurit; Kagan-Zur, Varda; Barak, Ze'ev; Guy, Ofer; Zaady, Eli; Lewinsohn, Efraim; Sitrit, Yaron

2017-03-28

Desert truffles are mycorrhizal, hypogeous fungi considered a delicacy. On the basis of morphological characters, we identified three desert truffle species that grow in the same habitat in the Negev desert. These include Picoa lefebvrei (Pat.), Tirmania nivea (Desf.) Trappe, and Terfezia boudieri (Chatain), all associated with Helianthemum sessiliflorum. Their taxonomy was confirmed by PCR-RFLP. The main volatiles of fruit bodies of T. boudieri and T. nivea were 1-octen-3-ol and hexanal; however, volatiles of the latter species further included branched-chain amino acid derivatives such as 2-methylbutanal and 3-methylbutanal, phenylalanine derivatives such as benzaldehyde and benzenacetaldehyde, and methionine derivatives such as methional and dimethyl disulfide. The least aromatic truffle, P. lefebvrei, contained low levels of 1-octen-3-ol as the main volatile. Axenic mycelia cultures of T. boudieri displayed a simpler volatile profile compared to its fruit bodies. This work highlights differences in the volatile profiles of desert truffles and could hence be of interest for selecting and cultivating genotypes with the most likable aroma.

The Early Gulf of Mexico as a Subaerial Basin Below Sea Level (SABSEL) Basin. Evidence from Stratigraphy and Facies of Luanne salt, Norphlet sandstone and Smackover Brown Dense Formations.

NASA Astrophysics Data System (ADS)

Cassidy, M. M.

2016-12-01

Many workers recognize that large salt deposits form in post-rift sag basins which were subaerial and susceptible to rapid flooding from adjacent oceansl. I have termed these basins "subaerial basins below sea level" or "SABSEL" basins. A key marker of SABSEL basins are terrestrial sediments immediately overlain by deepwater sediments with no transition. Desert deposits -including Aeolian dunes- are preserved in the adiabatically heated depression. Dunes are not eroded by transgressing seas but are drowned by rising water as in a bath tub. They maintain their shape. Deepwater marine black shales or limestones drape the dunes. The Southern North sea is an example. Above the original marine shale over the dunes are evaporites. Winds descending into the basin were heated by adiabatic compression providing the very hot air need to allow survival of potassium salts. A similar situation was probably active during the Messinian salinity crisis in the Mediterranean basin, and the opening of the South Atlantic. In the Gulf of Mexico (GOM) a desert is on the Louann salt. Here the sea invaded the lows first to deposit the salt overlying tilted fault blocks of the opening basin, as in the Afar Triangle of Africa. In the GOM entry to the west fed in sea water, then closed. The Norphlet desert formed. Streams carried sands to the basin to be spread by winds where they willed, not limited to sand entry areas. Upon deposition their original weight depressed the salt. Seismic shows depressions in the salt but the dunes are high at the top Norphlet, forming distinctive small "eyes" at the top salt. The 600 foot dunes are draped by deep water dolomitic finely laminated organic rich black/ brown shale, the Brown Dense Facies of the Smackover formation. The lack of reworking of the dunes found by detailed seismic is distinctive of deposition in a SABSEL basin. The overlap of terrestrial sediments by deep water deposition is good evidence of sudden flooding. In summary this vertical

Identification of microRNAs in Caragana intermedia by high-throughput sequencing and expression analysis of 12 microRNAs and their targets under salt stress.

PubMed

Zhu, Jianfeng; Li, Wanfeng; Yang, Wenhua; Qi, Liwang; Han, Suying

2013-09-01

142 miRNAs were identified and 38 miRNA targets were predicted, 4 of which were validated, in C. intermedia . The expression of 12 miRNAs in salt-stressed leaves was assessed by qRT-PCR. MicroRNAs (miRNAs) are endogenous small RNAs that play important roles in various biological and metabolic processes in plants. Caragana intermedia is an important ecological and economic tree species prominent in the desert environment of west and northwest China. To date, no investigation into C. intermedia miRNAs has been reported. In this study, high-throughput sequencing of small RNAs and analysis of transcriptome data were performed to identify both conserved and novel miRNAs, and also their target mRNA genes in C. intermedia. Based on sequence similarity and hairpin structure prediction, 132 putative conserved miRNAs (12 of which were confirmed to form hairpin precursors) belonging to 31 known miRNA families were identified. Ten novel miRNAs (including the miRNA* sequences of three novel miRNAs) were also discovered. Furthermore, 36 potential target genes of 17 known miRNA families and 2 potential target genes of 1 novel miRNA were predicted; 4 of these were validated by 5' RACE. The expression of 12 miRNAs was validated in different tissues, and these and five target mRNAs were assessed by qRT-PCR after salt treatment. The expression levels of seven miRNAs (cin-miR157a, cin-miR159a, cin-miR165a, cin-miR167b, cin-miR172b, cin-miR390a and cin-miR396a) were upregulated, while cin-miR398a expression was downregulated after salt treatment. The targets of cin-miR157a, cin-miR165a, cin-miR172b and cin-miR396a were downregulated and showed an approximately negative correlation with their corresponding miRNAs under salt treatment. These results would help further understanding of miRNA regulation in response to abiotic stress in C. intermedia.

Deriving Polarization Properties of Desert-Reflected Solar Spectra with PARASOL Data

NASA Technical Reports Server (NTRS)

Sun, Wenbo; Baize, Rosemary R.; Lukashin, Constantine

2015-01-01

Reflected solar radiation from desert is strongly polarized by sand particles. To date, there is no reliable desert surface reflection model to calculate desert reflection matrix. In this study, the PARASOL data are used to retrieve physical properties of desert. These physical properties are then used in the ADRTM to calculate polarization of desert-reflected light for the whole solar spectra.

Improved highway design methods for desert storms

DOT National Transportation Integrated Search

2007-08-01

This report provides identification of desert hydrologic regions within the arid and semi-arid portions of California, as well as information and direction in choosing appropriate hydrologic and bulking methods specific to each identified desert regi...

X-36 in Flight over Mojave Desert

NASA Image and Video Library

1997-10-30

The unusual lines of the X-36 technology demonstrator contrast sharply with the desert floor as the remotely piloted aircraft scoots across the California desert at low altitude during a research flight on October 30, 1997.

76 FR 50493 - Notice of Availability of the Record of Decision for the Desert Sunlight Holdings, LLC, Desert...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-08-15

... a solar photovoltaic (PV) facility, capable of producing 550 MW of electrical output. Southern... Sunlight Solar Farm (DSSF) and California Desert Conservation Area Plan Amendment, California AGENCY... . SUPPLEMENTARY INFORMATION: Desert Sunlight Holdings, LLC, a wholly owned subsidiary of First Solar, Inc., filed...

High-spatial resolution multispectral and panchromatic satellite imagery for mapping perennial desert plants

NASA Astrophysics Data System (ADS)

Alsharrah, Saad A.; Bruce, David A.; Bouabid, Rachid; Somenahalli, Sekhar; Corcoran, Paul A.

2015-10-01

The use of remote sensing techniques to extract vegetation cover information for the assessment and monitoring of land degradation in arid environments has gained increased interest in recent years. However, such a task can be challenging, especially for medium-spatial resolution satellite sensors, due to soil background effects and the distribution and structure of perennial desert vegetation. In this study, we utilised Pleiades high-spatial resolution, multispectral (2m) and panchromatic (0.5m) imagery and focused on mapping small shrubs and low-lying trees using three classification techniques: 1) vegetation indices (VI) threshold analysis, 2) pre-built object-oriented image analysis (OBIA), and 3) a developed vegetation shadow model (VSM). We evaluated the success of each approach using a root of the sum of the squares (RSS) metric, which incorporated field data as control and three error metrics relating to commission, omission, and percent cover. Results showed that optimum VI performers returned good vegetation cover estimates at certain thresholds, but failed to accurately map the distribution of the desert plants. Using the pre-built IMAGINE Objective OBIA approach, we improved the vegetation distribution mapping accuracy, but this came at the cost of over classification, similar to results of lowering VI thresholds. We further introduced the VSM which takes into account shadow for further refining vegetation cover classification derived from VI. The results showed significant improvements in vegetation cover and distribution accuracy compared to the other techniques. We argue that the VSM approach using high-spatial resolution imagery provides a more accurate representation of desert landscape vegetation and should be considered in assessments of desertification.

The Riparianness of a Desert Herpetofauna

Treesearch

Charles H. Lowe

1989-01-01

Within the Mojave, Sonoran, and Chihuahuan Desert subdivisions of the North American Desert in the U.S., more than half of 143 total amphibian and reptilian species perform as riparian and/or wetland taxa. For the reptiles, but not the amphibians, there is a significant inverse relationship between riparianness (obligate through preferential and facultative to...

Gopherus agassizii (desert tortoise). Burrow collapse

USGS Publications Warehouse

Loughran, Caleb L.; Ennen, Joshua; Lovich, Jeffrey E.

2011-01-01

In the deserts of the southwestern U.S., burrows are utilized by the Desert Tortoise to escape environmental extremes (reviewed by Ernst and Lovich 2009. Turtles of the United States and Canada. 2nd ed. Johns Hopkins Univ. Press, Baltimore, Maryland. 827 pp.). However, the potential for mortality through burrow collapse and entrapment is poorly documented. Nicholson and Humphreys (1981. Proceedings of the Desert Tortoise Council, pp. 163−194) suggested that collapse due to livestock trampling may cause mortality. In addition, Lovich et al. (2011. Chelon. Cons. Biol. 10[1]:124–129) documented a Desert Tortoise that used a steel culvert as a burrow surrogate. The culvert filled completely with sediment following a significant rain event, entombing the animal and ultimately resulting in its death. We note that this mortality was associated with an anthropogenic structure; because tortoises are prodigious diggers, one might hypothesize that they have the ability to dig out of collapsed natural burrows in most situations. Circumstances described here presented us with an opportunity to test this hypothesis.

Microbial ecology of hot desert edaphic systems.

PubMed

Makhalanyane, Thulani P; Valverde, Angel; Gunnigle, Eoin; Frossard, Aline; Ramond, Jean-Baptiste; Cowan, Don A

2015-03-01

A significant proportion of the Earth's surface is desert or in the process of desertification. The extreme environmental conditions that characterize these areas result in a surface that is essentially barren, with a limited range of higher plants and animals. Microbial communities are probably the dominant drivers of these systems, mediating key ecosystem processes. In this review, we examine the microbial communities of hot desert terrestrial biotopes (including soils, cryptic and refuge niches and plant-root-associated microbes) and the processes that govern their assembly. We also assess the possible effects of global climate change on hot desert microbial communities and the resulting feedback mechanisms. We conclude by discussing current gaps in our understanding of the microbiology of hot deserts and suggest fruitful avenues for future research. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Lidar Measurements for Desert Dust Characterization: An Overview

NASA Technical Reports Server (NTRS)

Mona, L.; Liu, Z.; Mueller, D.; Omar, A.; Papayannis, A.; Pappalardo, G.; Sugimoto, N.; Vaughan, M.

2012-01-01

We provide an overview of light detection and ranging (lidar) capability for describing and characterizing desert dust. This paper summarizes lidar techniques, observations, and fallouts of desert dust lidar measurements. The main objective is to provide the scientific community, including non-practitioners of lidar observations with a reference paper on dust lidar measurements. In particular, it will fill the current gap of communication between research-oriented lidar community and potential desert dust data users, such as air quality monitoring agencies and aviation advisory centers. The current capability of the different lidar techniques for the characterization of aerosol in general and desert dust in particular is presented. Technical aspects and required assumptions of these techniques are discussed, providing readers with the pros and cons of each technique. Information about desert dust collected up to date using lidar techniques is reviewed. Lidar techniques for aerosol characterization have a maturity level appropriate for addressing air quality and transportation issues, as demonstrated by some first results reported in this paper

Forecasting climate change impacts to plant community composition in the Sonoran Desert region

USGS Publications Warehouse

Munson, Seth M.; Webb, Robert H.; Belnap, Jayne; Hubbard, J. Andrew; Swann, Don E.; Rutman, Sue

2012-01-01

Hotter and drier conditions projected for the southwestern United States can have a large impact on the abundance and composition of long-lived desert plant species. We used long-term vegetation monitoring results from 39 large plots across four protected sites in the Sonoran Desert region to determine how plant species have responded to past climate variability. This cross-site analysis identified the plant species and functional types susceptible to climate change, the magnitude of their responses, and potential climate thresholds. In the relatively mesic mesquite savanna communities, perennial grasses declined with a decrease in annual precipitation, cacti increased, and there was a reversal of the Prosopis velutina expansion experienced in the 20th century in response to increasing mean annual temperature (MAT). In the more xeric Arizona Upland communities, the dominant leguminous tree, Cercidium microphyllum, declined on hillslopes, and the shrub Fouquieria splendens decreased, especially on south- and west-facing slopes in response to increasing MAT. In the most xeric shrublands, the codominant species Larrea tridentata and its hemiparasite Krameria grayi decreased with a decrease in cool season precipitation and increased aridity, respectively. This regional-scale assessment of plant species response to recent climate variability is critical for forecasting future shifts in plant community composition, structure, and productivity.

Hygroscopic salts and the potential for life on Mars.

PubMed

Davila, Alfonso F; Duport, Luis Gago; Melchiorri, Riccardo; Jänchen, Jochen; Valea, Sergio; de Los Rios, Asunción; Fairén, Alberto G; Möhlmann, Diedrich; McKay, Christopher P; Ascaso, Carmen; Wierzchos, Jacek

2010-01-01

Hygroscopic salts have been detected in soils in the northern latitudes of Mars, and widespread chloride-bearing evaporitic deposits have been detected in the southern highlands. The deliquescence of hygroscopic minerals such as chloride salts could provide a local and transient source of liquid water that would be available for microorganisms on the surface. This is known to occur in the Atacama Desert, where massive halite evaporites have become a habitat for photosynthetic and heterotrophic microorganisms that take advantage of the deliquescence of the salt at certain relative humidity (RH) levels. We modeled the climate conditions (RH and temperature) in a region on Mars with chloride-bearing evaporites, and modeled the evolution of the water activity (a(w)) of the deliquescence solutions of three possible chloride salts (sodium chloride, calcium chloride, and magnesium chloride) as a function of temperature. We also studied the water absorption properties of the same salts as a function of RH. Our climate model results show that the RH in the region with chloride-bearing deposits on Mars often reaches the deliquescence points of all three salts, and the temperature reaches levels above their eutectic points seasonally, in the course of a martian year. The a(w) of the deliquescence solutions increases with decreasing temperature due mainly to the precipitation of unstable phases, which removes ions from the solution. The deliquescence of sodium chloride results in transient solutions with a(w) compatible with growth of terrestrial microorganisms down to 252 K, whereas for calcium chloride and magnesium chloride it results in solutions with a(w) below the known limits for growth at all temperatures. However, taking the limits of a(w) used to define special regions on Mars, the deliquescence of calcium chloride deposits would allow for the propagation of terrestrial microorganisms at temperatures between 265 and 253 K, and for metabolic activity (no growth) at

Extensive gene tree discordance and hemiplasy shaped the genomes of North American columnar cacti.

PubMed

Copetti, Dario; Búrquez, Alberto; Bustamante, Enriquena; Charboneau, Joseph L M; Childs, Kevin L; Eguiarte, Luis E; Lee, Seunghee; Liu, Tiffany L; McMahon, Michelle M; Whiteman, Noah K; Wing, Rod A; Wojciechowski, Martin F; Sanderson, Michael J

2017-11-07

Few clades of plants have proven as difficult to classify as cacti. One explanation may be an unusually high level of convergent and parallel evolution (homoplasy). To evaluate support for this phylogenetic hypothesis at the molecular level, we sequenced the genomes of four cacti in the especially problematic tribe Pachycereeae, which contains most of the large columnar cacti of Mexico and adjacent areas, including the iconic saguaro cactus ( Carnegiea gigantea ) of the Sonoran Desert. We assembled a high-coverage draft genome for saguaro and lower coverage genomes for three other genera of tribe Pachycereeae ( Pachycereus , Lophocereus , and Stenocereus ) and a more distant outgroup cactus, Pereskia We used these to construct 4,436 orthologous gene alignments. Species tree inference consistently returned the same phylogeny, but gene tree discordance was high: 37% of gene trees having at least 90% bootstrap support conflicted with the species tree. Evidently, discordance is a product of long generation times and moderately large effective population sizes, leading to extensive incomplete lineage sorting (ILS). In the best supported gene trees, 58% of apparent homoplasy at amino sites in the species tree is due to gene tree-species tree discordance rather than parallel substitutions in the gene trees themselves, a phenomenon termed "hemiplasy." The high rate of genomic hemiplasy may contribute to apparent parallelisms in phenotypic traits, which could confound understanding of species relationships and character evolution in cacti. Published under the PNAS license.

Extensive gene tree discordance and hemiplasy shaped the genomes of North American columnar cacti

PubMed Central

Búrquez, Alberto; Bustamante, Enriquena; Charboneau, Joseph L. M.; Childs, Kevin L.; Eguiarte, Luis E.; Lee, Seunghee; Liu, Tiffany L.; McMahon, Michelle M.; Whiteman, Noah K.; Wing, Rod A.; Wojciechowski, Martin F.; Sanderson, Michael J.

2017-01-01

Few clades of plants have proven as difficult to classify as cacti. One explanation may be an unusually high level of convergent and parallel evolution (homoplasy). To evaluate support for this phylogenetic hypothesis at the molecular level, we sequenced the genomes of four cacti in the especially problematic tribe Pachycereeae, which contains most of the large columnar cacti of Mexico and adjacent areas, including the iconic saguaro cactus (Carnegiea gigantea) of the Sonoran Desert. We assembled a high-coverage draft genome for saguaro and lower coverage genomes for three other genera of tribe Pachycereeae (Pachycereus, Lophocereus, and Stenocereus) and a more distant outgroup cactus, Pereskia. We used these to construct 4,436 orthologous gene alignments. Species tree inference consistently returned the same phylogeny, but gene tree discordance was high: 37% of gene trees having at least 90% bootstrap support conflicted with the species tree. Evidently, discordance is a product of long generation times and moderately large effective population sizes, leading to extensive incomplete lineage sorting (ILS). In the best supported gene trees, 58% of apparent homoplasy at amino sites in the species tree is due to gene tree-species tree discordance rather than parallel substitutions in the gene trees themselves, a phenomenon termed “hemiplasy.” The high rate of genomic hemiplasy may contribute to apparent parallelisms in phenotypic traits, which could confound understanding of species relationships and character evolution in cacti. PMID:29078296

Nationwide Desert Highway Assessment: A Case Study in China

PubMed Central

Mao, Xuesong; Wang, Fuchun; Wang, Binggang

2011-01-01

The natural environment affects the construction of desert highways. Conversely, highway construction affects the natural environment and puts the ecological environment at a disadvantage. To satisfy the variety and hierarchy of desert highway construction and discover the spatio-temporal distribution of the natural environment and its effect on highway construction engineering, an assessment of the natural regional divisions of desert highways in China is carried out for the first time. Based on the general principles and method for the natural region division, the principles, method and index system for desert highway assessment is put forward by combining the desert highway construction features and the azonal differentiation law. The index system combines the dominant indicator and four auxiliary indicators. The dominant indicator is defined by the desert’s comprehensive state index and the auxiliary indicators include the sand dune height, the blown sand strength, the vegetation coverage ratio and the annual average temperature difference. First the region is divided according to the dominant indicator. Then the region boundaries are amended according to the four auxiliary indicators. Finally the natural region division map for desert highway assessment is presented. The Chinese desert highways can be divided into three sections: the east medium effect region, the middle medium-severe effect region, and the west slight-medium effect region. The natural region division map effectively paves the way for the route planning, design, construction, maintenance and ongoing management of desert highways, and further helps environmental protection. PMID:21845155

A mathematical model on the optimal timing of offspring desertion.

PubMed

Seno, Hiromi; Endo, Hiromi

2007-06-07

We consider the offspring desertion as the optimal strategy for the deserter parent, analyzing a mathematical model for its expected reproductive success. It is shown that the optimality of the offspring desertion significantly depends on the offsprings' birth timing in the mating season, and on the other ecological parameters characterizing the innate nature of considered animals. Especially, the desertion is less likely to occur for the offsprings born in the later period of mating season. It is also implied that the offspring desertion after a partially biparental care would be observable only with a specific condition.

An evaluation of supervised classifiers for indirectly detecting salt-affected areas at irrigation scheme level

NASA Astrophysics Data System (ADS)

Muller, Sybrand Jacobus; van Niekerk, Adriaan

2016-07-01

Soil salinity often leads to reduced crop yield and quality and can render soils barren. Irrigated areas are particularly at risk due to intensive cultivation and secondary salinization caused by waterlogging. Regular monitoring of salt accumulation in irrigation schemes is needed to keep its negative effects under control. The dynamic spatial and temporal characteristics of remote sensing can provide a cost-effective solution for monitoring salt accumulation at irrigation scheme level. This study evaluated a range of pan-fused SPOT-5 derived features (spectral bands, vegetation indices, image textures and image transformations) for classifying salt-affected areas in two distinctly different irrigation schemes in South Africa, namely Vaalharts and Breede River. The relationship between the input features and electro conductivity measurements were investigated using regression modelling (stepwise linear regression, partial least squares regression, curve fit regression modelling) and supervised classification (maximum likelihood, nearest neighbour, decision tree analysis, support vector machine and random forests). Classification and regression trees and random forest were used to select the most important features for differentiating salt-affected and unaffected areas. The results showed that the regression analyses produced weak models (<0.4 R squared). Better results were achieved using the supervised classifiers, but the algorithms tend to over-estimate salt-affected areas. A key finding was that none of the feature sets or classification algorithms stood out as being superior for monitoring salt accumulation at irrigation scheme level. This was attributed to the large variations in the spectral responses of different crops types at different growing stages, coupled with their individual tolerances to saline conditions.

Image-based terrain modeling with thematic mapper applied to resolving the limit of Holocene Lake expansion in the Great Salt Lake Desert, Utah, part 1

NASA Technical Reports Server (NTRS)

Merola, John A.

1989-01-01

The LANDSAT Thematic Mapper (TM) scanner records reflected solar energy from the earth's surface in six wavelength regions, or bands, and one band that records emitted energy in the thermal region, giving a total of seven bands. Useful research was extracted about terrain morphometry from remote sensing measurements and this information is used in an image-based terrain model for selected coastal geomorphic features in the Great Salt Lake Desert (GSLD). Technical developments include the incorporation of Aerial Profiling of Terrain System (APTS) data in satellite image analysis, and the production and use of 3-D surface plots of TM reflectance data. Also included in the technical developments is the analysis of the ground control point spatial distribution and its affects on geometric correction, and the terrain mapping procedure; using satellite data in a way that eliminates the need to degrade the data by resampling. The most common approach for terrain mapping with multispectral scanner data includes the techniques of pattern recognition and image classification, as opposed to direct measurement of radiance for identification of terrain features. The research approach in this investigation was based on an understanding of the characteristics of reflected light resulting from the variations in moisture and geometry related to terrain as described by the physical laws of radiative transfer. The image-based terrain model provides quantitative information about the terrain morphometry based on the physical relationship between TM data, the physical character of the GSLD, and the APTS measurements.

Arbuscular mycorrhizal fungi increase salt tolerance of apple seedlings.

PubMed

Yang, Shou-Jun; Zhang, Zhong-Lan; Xue, Yuan-Xia; Zhang, Zhi-Fen; Shi, Shu-Yi

2014-12-01

Apple trees are often subject to severe salt stress in China as well as in the world that results in significant loss of apple production. Therefore this study was carried out to evaluate the response of apple seedlings inoculated with abuscular mycorrhizal fungi under 0, 2‰, 4‰ and 6‰ salinity stress levels and further to conclude the upper threshold of mycorrhizal salinity tolerance. The results shows that abuscular mycorrhizal fungi significantly increased the root length colonization of mycorrhizal apple plants with exposure time period to 0, 2‰ and 4‰ salinity levels as compared to non-mycorrhizal plants, however, percent root colonization reduced as saline stress increased. Salinity levels were found to negatively correlate with leaf relative turgidity, osmotic potential irrespective of non-mycorrhizal and mycorrhizal apple plants, but the decreased mycorrhizal leaf turgidity maintained relative normal values at 2‰ and 4‰ salt concentrations. Under salt stress condition, Cl - and Na + concentrations clearly increased and K + contents obviously decreased in non-mycorrhizal roots in comparison to mycorrhizal plants, this caused mycorrhizal plants had a relatively higher K + /Na + ratio in root. In contrast to zero salinity level, although ascorbate peroxidase and catalase activities in non-inoculated and inoculated leaf improved under all saline levels, the extent of which these enzymes increased was greater in mycorrhizal than in non-mycorrhizal plants. The numbers of survived tree with non-mycorrhization were 40, 20 and 0 (i.e., 66.7%, 33.3% and 0) on the days of 30, 60 and 90 under 4‰ salinity, similarly in mycorrhization under 6‰ salinity 40, 30 and 0 (i.e., 66.7%, 50% and 0) respectively. These results suggest that 2‰ and 4‰ salt concentrations may be the upper thresholds of salinity tolerance in non-mycorrhizal and mycorrhizal apple plants, respectively.

Tree-ring reconstruction of the level of Great Salt Lake, USA

Treesearch

R. Justin DeRose; Shih-Yu Wang; Brendan M. Buckley; Matthew F. Bekker

2014-01-01

Utah's Great Salt Lake (GSL) is a closed-basin remnant of the larger Pleistocene-age Lake Bonneville. The modern instrumental record of the GSL-level (i.e. elevation) change is strongly modulated by Pacific Ocean coupled ocean/atmospheric oscillations at low frequency, and therefore reflects the decadalscale wet/dry cycles that characterize the region. A within-...

Ultraviolet radiation in the Atacama Desert.

PubMed

Cordero, R R; Damiani, A; Jorquera, J; Sepúlveda, E; Caballero, M; Fernandez, S; Feron, S; Llanillo, P J; Carrasco, J; Laroze, D; Labbe, F

2018-03-31

The world's highest levels of surface ultraviolet (UV) irradiance have been measured in the Atacama Desert. This area is characterized by its high altitude, prevalent cloudless conditions, and a relatively low total ozone column. In this paper, we provide estimates of the surface UV (monthly UV index at noon and annual doses of UV-B and UV-A) for all sky conditions in the Atacama Desert. We found that the UV index at noon during the austral summer is expected to be greater than 11 in the whole desert. The annual UV-B (UV-A) doses were found to range from about 3.5 kWh/m 2 (130 kWh/m 2 ) in coastal areas to 5 kWh/m 2 (160 kWh/m 2 ) on the Andean plateau. Our results confirm significant interhemispherical differences. Typical annual UV-B doses in the Atacama Desert are about 40% greater than typical annual UV-B doses in northern Africa. Mostly due to seasonal changes in the ozone, the differences between the Atacama Desert and northern Africa are expected to be about 60% in the case of peak UV-B levels (i.e. the UV-B irradiances at noon close to the summer solstice in each hemisphere). Interhemispherical differences in the UV-A are significantly lower since the effect of the ozone in this part of the spectrum is minor.

Observational Evidence for Desert Amplification Using Multiple Satellite Datasets.

PubMed

Wei, Nan; Zhou, Liming; Dai, Yongjiu; Xia, Geng; Hua, Wenjian

2017-05-17

Desert amplification identified in recent studies has large uncertainties due to data paucity over remote deserts. Here we present observational evidence using multiple satellite-derived datasets that desert amplification is a real large-scale pattern of warming mode in near surface and low-tropospheric temperatures. Trend analyses of three long-term temperature products consistently confirm that near-surface warming is generally strongest over the driest climate regions and this spatial pattern of warming maximizes near the surface, gradually decays with height, and disappears in the upper troposphere. Short-term anomaly analyses show a strong spatial and temporal coupling of changes in temperatures, water vapor and downward longwave radiation (DLR), indicating that the large increase in DLR drives primarily near surface warming and is tightly associated with increasing water vapor over deserts. Atmospheric soundings of temperature and water vapor anomalies support the results of the long-term temperature trend analysis and suggest that desert amplification is due to comparable warming and moistening effects of the troposphere. Likely, desert amplification results from the strongest water vapor feedbacks near the surface over the driest deserts, where the air is very sensitive to changes in water vapor and thus efficient in enhancing the longwave greenhouse effect in a warming climate.

Modeling Habitat of the Desert Tortoise (Gopherus agassizii) in the Mojave and Parts of the Sonoran Deserts of California, Nevada, Utah, and Arizona

USGS Publications Warehouse

Nussear, Kenneth E.; Esque, Todd C.; Inman, Richard D.; Gass, Leila; Thomas, Kathryn A.; Wallace, Cynthia S.A.; Blainey, Joan B.; Miller, David M.; Webb, Robert H.

2009-01-01

Habitat modeling is an important tool used to simulate the potential distribution of a species for a variety of basic and applied questions. The desert tortoise (Gopherus agassizii) is a federally listed threatened species in the Mojave Desert and parts of the Sonoran Desert of California, Nevada, Utah, and Arizona. Land managers in this region require reliable information about the potential distribution of desert tortoise habitat to plan conservation efforts, guide monitoring activities, monitor changes in the amount and quality of habitat available, minimize and mitigate disturbances, and ultimately to assess the status of the tortoise and its habitat toward recovery of the species. By applying information from the literature and our knowledge or assumptions of environmental variables that could potentially explain variability in the quality of desert tortoise habitat, we developed a quantitative habitat model for the desert tortoise using an extensive set of field-collected presence data. Sixteen environmental data layers were converted into a grid covering the study area and merged with the desert tortoise presence data that we gathered for input into the Maxent habitat-modeling algorithm. This model provides output of the statistical probability of habitat potential that can be used to map potential areas of desert tortoise habitat. This type of analysis, while robust in its predictions of habitat, does not account for anthropogenic changes that may have altered habitat with relatively high potential into areas with lower potential.

Enhancing and restoring habitat for the desert tortoise

USGS Publications Warehouse

Abella, Scott R.; Berry, Kristin H.

2016-01-01

Habitat has changed unfavorably during the past 150 y for the desert tortoise Gopherus agassizii, a federally threatened species with declining populations in the Mojave Desert and western Sonoran Desert. To support recovery efforts, we synthesized published information on relationships of desert tortoises with three habitat features (cover sites, forage, and soil) and candidate management practices for improving these features for tortoises. In addition to their role in soil health and facilitating recruitment of annual forage plants, shrubs are used by desert tortoises for cover and as sites for burrows. Outplanting greenhouse-grown seedlings, protected from herbivory, has successfully restored (>50% survival) a variety of shrubs on disturbed desert soils. Additionally, salvaging and reapplying topsoil using effective techniques is among the more ecologically beneficial ways to initiate plant recovery after severe disturbance. Through differences in biochemical composition and digestibility, some plant species provide better-quality forage than others. Desert tortoises selectively forage on particular annual and herbaceous perennial species (e.g., legumes), and forage selection shifts during the year as different plants grow or mature. Nonnative grasses provide low-quality forage and contribute fuel to spreading wildfires, which damage or kill shrubs that tortoises use for cover. Maintaining a diverse “menu” of native annual forbs and decreasing nonnative grasses are priorities for restoring most desert tortoise habitats. Reducing herbivory by nonnative animals, carefully timing herbicide applications, and strategically augmenting annual forage plants via seeding show promise for improving tortoise forage quality. Roads, another disturbance, negatively affect habitat in numerous ways (e.g., compacting soil, altering hydrology). Techniques such as recontouring road berms to reestablish drainage patterns, vertical mulching (“planting” dead plant material

Identification of debris-flow hazards in warm deserts through analyzing past occurrences: Case study in South Mountain, Sonoran Desert, USA

NASA Astrophysics Data System (ADS)

Dorn, Ronald I.

2016-11-01

After recognition that debris flows co-occur with human activities, the next step in a hazards analysis involves estimating debris-flow probability. Prior research published in this journal in 2010 used varnish microlamination (VML) dating to determine a minimum occurrence of 5 flows per century over the last 8100 years in a small mountain range of South Mountain adjacent to neighborhoods of Phoenix, Arizona. This analysis led to the conclusion that debris flows originating in small mountain ranges in arid regions like the Sonoran Desert could pose a hazard. Two major precipitation events in the summer of 2014 generated 35 debris flows in the same study area of South Mountain-providing support for the importance of probability analysis as a key step in a hazards analysis in warm desert settings. Two distinct mechanisms generated the 2014 debris flows: intense precipitation on steep slopes in the first storm; and a firehose effect whereby runoff from the second storm was funneled rapidly by cleaned-out debris-flow chutes to remobilize Pleistocene debris-flow deposits. When compared to a global database on debris flows, the 2014 storms were among the most intense to generate desert debris flows - indicating that storms of lesser intensity are capable of generating debris flows in warm desert settings. The 87Sr/86Sr analyses of fines and clasts in South Mountain debris flows of different ages reveal that desert dust supplies the fines. Thus, wetter climatic periods of intense rock decay are not needed to resupply desert slopes with fines; instead, a combination of dust deposition supplying fines and dirt cracking generating coarse clasts can re-arm chutes in a warm desert setting with abundant dust.

Oxalate secretion by ectomycorrhizal Paxillus involutus is mineral-specific and controls calcium weathering from minerals

NASA Astrophysics Data System (ADS)

Schmalenberger, A.; Duran, A. L.; Bray, A. W.; Bridge, J.; Bonneville, S.; Benning, L. G.; Romero-Gonzalez, M. E.; Leake, J. R.; Banwart, S. A.

2015-07-01

Trees and their associated rhizosphere organisms play a major role in mineral weathering driving calcium fluxes from the continents to the oceans that ultimately control long-term atmospheric CO2 and climate through the geochemical carbon cycle. Photosynthate allocation to tree roots and their mycorrhizal fungi is hypothesized to fuel the active secretion of protons and organic chelators that enhance calcium dissolution at fungal-mineral interfaces. This was tested using 14CO2 supplied to shoots of Pinus sylvestris ectomycorrhizal with the widespread fungus Paxillus involutus in monoxenic microcosms, revealing preferential allocation by the fungus of plant photoassimilate to weather grains of limestone and silicates each with a combined calcium and magnesium content of over 10 wt.%. Hyphae had acidic surfaces and linear accumulation of weathered calcium with secreted oxalate, increasing significantly in sequence: quartz, granite < basalt, olivine, limestone < gabbro. These findings confirmed the role of mineral-specific oxalate exudation in ectomycorrhizal weathering to dissolve calcium bearing minerals, thus contributing to the geochemical carbon cycle.

An experimental analysis of granivory in desert ecosystems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Davidson, D.W.

1988-01-01

In our studies of desert granivore ecology, we have outlined the network of interaction pathways linking granivore and resource species in a Chihuahuan Desert Ecosystem. Here, a major fraction of the primary productivity takes the form of the seeds of annual plants. These seeds support two major resident taxa of desert granivores, ants and rodents. Population responses to removal of various taxa of granivores or seasonal classes of resource species are described.

Browning in Desert Boundaries in Asia in Recent Decades

NASA Technical Reports Server (NTRS)

Jeong, Su-Jong; Ho, Chang-Hoi; Brown, Molly E.; Kug, Jong-Seong; Piao, Shilong

2011-01-01

In this study, the changes in desert boundaries in Asia (Gobi, Karakum, Lut, Taklimakan, and Thar deserts) during the growing season (April October) in the years 1982 2008 were investigated by analyzing the normalized difference vegetation index (NDVI), precipitation, and temperature. In the desert boundary regions, the domain mean NDVI values increased by 7.2% per decade in 1982 1998 but decreased by 6.8% per decade thereafter. Accordingly, the bare soil areas (or nonvegetated areas) of the inside of the desert boundaries contracted by 9.8% per decade in the 1990s and expanded by 8.7% per decade in the 2000s. It is noted that the five deserts experience nearly simultaneous NDVI changes although they cover a very diverse area of Asia. In contrast, changes in temperature and precipitation in the deserts show rather diverse results. In desert boundaries located along 40 N (Gobi, Taklimakan, and Karakum), the decadal changes in vegetation greenness were mainly related to regional climate during the entire analysis period. Precipitation increased in the 1990s, providing favorable conditions for vegetation growth (i.e., greening), but precipitation reduced (19 mm per decade) and warming intensified (0.7 C per decade) in the 2000s, causing less moisture to be available for vegetation growth (i.e., browning). In desert boundaries below 40 N (Lut and Thar), although an increase in precipitation (8 mm per decade) led to greening in the 1990s, local changes in precipitation and temperature did not necessarily cause browning in the 2000s. Observed multidecadal changes in vegetation greenness in the present study suggest that under significant global and/or regional warming, changes in moisture availability for vegetation growth in desert boundaries are an important factor when understanding decadal changes in areas vulnerable to desertification over Asia.

Growth responses of five desert plants as influenced by biological soil crusts from a temperate desert, China

USGS Publications Warehouse

Zhang, Yuanming; Belnap, Jayne

2015-01-01

In almost all dryland systems, biological soil crusts (biocrusts) coexist alongside herbaceous and woody vegetation, creating landscape mosaics of vegetated and biocrusted patches. Results from past studies on the interaction between biocrusts and vascular plants have been contradictory. In the Gurbantunggut desert, a large temperate desert in northwestern China, well-developed lichen-dominated crusts dominate the areas at the base and between the sand dunes. We examined the influence of these lichen-dominated biocrusts on the germination, growth, biomass accumulation, and elemental content of five common plants in this desert: two shrubs (Haloxylon persicum, Ephedra distachya) and three herbaceous plants (Ceratocarpus arenarius, Malcolmia africana and Lappula semiglabra) under greenhouse conditions. The influence of biocrusts on seed germination was species-specific. Biocrusts did not affect percent germination in plants with smooth seeds, but inhibited germination of seeds with appendages that reduced or eliminated contact with the soil surface or prevented seeds from slipping into soil cracks. Once seeds had germinated, biocrusts had different influences on growth of shrub and herbaceous plants. The presence of biocrusts increased concentrations of nitrogen but did not affect phosphorus or potassium in tissue of all tested species, while the uptake of the other tested nutrients was species-specific. Our study showed that biocrusts can serve as a biological filter during seed germination and also can influence growth and elemental uptake. Therefore, they may be an important trigger for determining desert plant diversity and community composition in deserts.

The Use of Water During the Crew 144, Mars Desert Research Station, Utah Desert

NASA Astrophysics Data System (ADS)

De Morais Mendonca Teles, Antonio

2016-07-01

Well. from November 29th to December 14th, 2014, the author conducted astrobiological and geological surveys, as analog astronaut member of the international Crew 144, at the site of the Mars Society's Mars Desert Research Station, located at a remote location in the Utah desert, United States. The use of water for drinking, bathing, cleaning, etc., in the crew was a major issue for consideration for a human expedition to the planet Mars in the future. The author would like to tell about the factors of the rationalized use of water.

Salt tolerance at single cell level in giant-celled Characeae

PubMed Central

Beilby, Mary J.

2015-01-01

Characean plants provide an excellent experimental system for electrophysiology and physiology due to: (i) very large cell size, (ii) position on phylogenetic tree near the origin of land plants and (iii) continuous spectrum from very salt sensitive to very salt tolerant species. A range of experimental techniques is described, some unique to characean plants. Application of these methods provided electrical characteristics of membrane transporters, which dominate the membrane conductance under different outside conditions. With this considerable background knowledge the electrophysiology of salt sensitive and salt tolerant genera can be compared under salt and/or osmotic stress. Both salt tolerant and salt sensitive Characeae show a rise in membrane conductance and simultaneous increase in Na+ influx upon exposure to saline medium. Salt tolerant Chara longifolia and Lamprothamnium sp. exhibit proton pump stimulation upon both turgor decrease and salinity increase, allowing the membrane PD to remain negative. The turgor is regulated through the inward K+ rectifier and 2H+/Cl- symporter. Lamprothamnium plants can survive in hypersaline media up to twice seawater strength and withstand large sudden changes in salinity. Salt sensitive C. australis succumbs to 50–100 mM NaCl in few days. Cells exhibit no pump stimulation upon turgor decrease and at best transient pump stimulation upon salinity increase. Turgor is not regulated. The membrane PD exhibits characteristic noise upon exposure to salinity. Depolarization of membrane PD to excitation threshold sets off trains of action potentials, leading to further loses of K+ and Cl-. In final stages of salt damage the H+/OH- channels are thought to become the dominant transporter, dissipating the proton gradient and bringing the cell PD close to 0. The differences in transporter electrophysiology and their synergy under osmotic and/or saline stress in salt sensitive and salt tolerant characean cells are discussed in

Pioneer unmanned air vehicle accomplishments during Operation Desert Storm

NASA Astrophysics Data System (ADS)

Christner, James H.

1991-12-01

This paper will describe the accomplishments and lessons learned of the Pioneer Unmanned Air Vehicle (UAV) during Operations Desert Shield and Desert Storm. The Pioneer UAV has been deployed with three branches of the U.S. military (USA, USN, and USMC) for the past four years. Although the system has compiled over 6,000 flight hours, the recent conflict in the Gulf is the first opportunity to demonstrate its true value in a combat scenario. In a relatively short time (42 days), 307 flights and 1,011 flight hours were completed on Operation Desert Storm. This, coupled with the accuracy of various weapons systems that Pioneer observed/cued for, resulted in timely target engagements. This paper will chronicle the Pioneer deployment and accomplishments on Operations Desert Shield and Desert Storm. Various employment methods, tactics, doctrine, and lessons learned will be presented.

Hydrology and surface morphology of the Bonneville Salt Flats and Pilot Valley Playa, Utah

USGS Publications Warehouse

Lines, Gregory C.

1979-01-01

The Bonneville Salt Flats and Pilot Valley are in the western part of the Great Salt Lake Desert in northwest Utah. The areas are separate, though similar, hydrologic basins, and both contain a salt crust. The Bonneville salt crust covered about 40 square miles in the fall of 1976, and the salt crust in Pilot Valley covered 7 square miles. Both areas lack any noticeable surface relief (in 1976, 1.3 feet on the Bonneville salt crust and 0.3 foot on the Pilot Valley salt crust).The salt crust on the Salt Flats has been used for many years for automobile racing, and brines from shallow lacustrine deposits have been used for the production of potash. In recent years, there has been an apparent conflict between these two major uses of the area as the salt crust has diminished in both thickness and extent. Much of the Bonneville Racetrack has become rougher, and there has also been an increase in the amount of sediment on the south end of the racetrack. The Pilot Valley salt crust and surrounding playa have been largely unused.Evaporite minerals on the Salt Flats and the Pilot Valley playa are concentrated in three zones: (1) a carbonate zone composed mainly of authigenic clay-size carbonate minerals, (2) a sulfate zone composed mainly of authigenic gypsum, and (3) a chloride zone composed of crystalline halite (the salt crust). Five major types of salt crust were recognized on the Salt Flats, but only one type was observed in Pilot Valley. Geomorphic differences in the salt crust are caused by differences in their hydrologic environments. The salt crusts are dynamic features that are subject to change because of climatic factors and man's activities.Ground water occurs in three distinct aquifers in much of the western Great Salt Lake Desert: (1) the basin-fill aquifer, which yields water from conglomerate in the lower part of the basin fill, (2) the alluvial-fan aquifer, which yields water from sand and gravel along the western margins of both playas, and (3) the

Desert Survivors!

ERIC Educational Resources Information Center

Horton, Jessica; Friedenstab, Steve

2013-01-01

This article describes a special third-grade classroom unit based on the reality show "Survivor." The goal of this engaging and interactive unit was to teach students about physical and behavioral adaptations that help animals survive in various desert biomes. The activity combines research, argument, and puppet play over one week of…

Notes from the Great American Desert

ERIC Educational Resources Information Center

Grady, Marilyn L.; LaCost, Barbara Y.

2005-01-01

In the good old days, the state that is Nebraska was identified as part of the Great American Desert. In many ways, in climate and terrain, it still bears a resemblance to a desert. As a frontier or a land of pioneers, it deserves recognition. Invisibility may be one of the greatest challenges women face. One of the great flaws in the writing of…

Agreement: Desert Community College District, College of the Desert Faculty Association CTA/NEA, January 13, 1989-June 30, 1989.

ERIC Educational Resources Information Center

Desert Community Coll. District, Palm Desert, CA.

The collective bargaining agreement between the Desert Community College District and the College of the Desert Faculty Association/California Teachers Association/National Education Association is presented. This contract, covering the period from January 13, 1989 through June 30, 1989, deals with the following topics: bargaining agent…

Collective Bargaining Agreement, 1989-1992, between College of the Desert Faculty Association CTA/NEA and Desert Community College District.

ERIC Educational Resources Information Center

Desert Community Coll. District, Palm Desert, CA.

The collective bargaining agreement between Desert Community College District Board of Trustees and the College of the Desert Faculty Association/California Teachers Association/National Education Association is presented. This contract, covering the period from November 17, 1989 through June 30, 1992, deals with the following topics: bargaining…

Evaluating Micrometeorological Estimates of Groundwater Discharge from Great Basin Desert Playas.

PubMed

Jackson, Tracie R; Halford, Keith J; Gardner, Philip M

2018-03-06

Groundwater availability studies in the arid southwestern United States traditionally have assumed that groundwater discharge by evapotranspiration (ET g ) from desert playas is a significant component of the groundwater budget. However, desert playa ET g rates are poorly constrained by Bowen ratio energy budget (BREB) and eddy-covariance (EC) micrometeorological measurement approaches. Best attempts by previous studies to constrain ET g from desert playas have resulted in ET g rates that are within the measurement error of micrometeorological approaches. This study uses numerical models to further constrain desert playa ET g rates that are within the measurement error of BREB and EC approaches, and to evaluate the effect of hydraulic properties and salinity-based groundwater density contrasts on desert playa ET g rates. Numerical models simulated ET g rates from desert playas in Death Valley, California and Dixie Valley, Nevada. Results indicate that actual ET g rates from desert playas are significantly below the uncertainty thresholds of BREB- and EC-based micrometeorological measurements. Discharge from desert playas likely contributes less than 2% of total groundwater discharge from Dixie and Death Valleys, which suggests discharge from desert playas also is negligible in other basins. Simulation results also show that ET g from desert playas primarily is limited by differences in hydraulic properties between alluvial fan and playa sediments and, to a lesser extent, by salinity-based groundwater density contrasts. Published 2018. This article is a U.S. Government work and is in the public domain in the USA.

Evaluating Micrometeorological Estimates of Groundwater Discharge from Great Basin Desert Playas

NASA Astrophysics Data System (ADS)

Jackson, T.; Halford, K. J.; Gardner, P.

2017-12-01

Groundwater availability studies in the arid southwestern United States traditionally have assumed that groundwater discharge by evapotranspiration (ETg) from desert playas is a significant component of the groundwater budget. This result occurs because desert playa ETg rates are poorly constrained by Bowen Ratio energy budget (BREB) and eddy-covariance (EC) micrometeorological measurement approaches. Best attempts by previous studies to constrain ETg from desert playas have resulted in ETg rates that are below the detection limit of micrometeorological approaches. This study uses numerical models to further constrain desert playa ETg rates that are below the detection limit of EC (0.1 mm/d) and BREB (0.3 mm/d) approaches, and to evaluate the effect of hydraulic properties and salinity-based groundwater-density contrasts on desert playa ETg rates. Numerical models simulated ETg rates from desert playas in Death Valley, California and Dixie Valley, Nevada. Results indicate that actual ETg rates from desert playas are significantly below the upper detection limits provided by the BREB- and EC-based micrometeorological measurements. Discharge from desert playas contribute less than 2 percent of total groundwater discharge from Dixie and Death Valleys, which suggests discharge from desert playas is negligible in other basins. Numerical simulation results also show that ETg from desert playas primarily is limited by differences in hydraulic properties between alluvial fan and playa sediments and, to a lesser extent, by salinity-based groundwater density contrasts.

Desert Express: An Analysis on Improved Customer Service

DTIC Science & Technology

1991-09-01

Nt MARQ 3,199 Of. DESERT EXPRESS: AN ANALYSIS ON IMPROVED CUSTOMER SERVICE THESIS Thomas C Thaiheim, Majo-,r USAF AFTT/GLM/LSM,/91S-64 ?Z; W...Astq vt.: tyc a l AFIT/GLM/,LSM/91S-64 DESERT EXPRESS: AN ANALYSIS ON IMPROVED CUSTOMER SERVICE THESIS Thomas C. Thalheim, Major, USAF AFIT/GLM/LSM...91S-64 Approved for public release; distribution unlimited AFIT/GLM/LSM/91S-64 DESERT EXPRESS: AN ANALYSIS ON IMPROVED CUSTOMER SERVICE THESIS

Potentials and problems of sustainable irrigation with water high in salts

NASA Astrophysics Data System (ADS)

Ben-Gal, Alon

2015-04-01

Water scarcity and need to expand agricultural productivity have led to ever growing utilization of poor quality water for irrigation of crops. Almost in all cases, marginal or alternative water sources for irrigation contain relatively high concentrations of dissolved salts. When salts are present, irrigation water management, especially in the dry regions where water requirements are highest, must consider leaching in addition to crop evapotranspiration requirements. Leaching requirements for agronomic success are calculable and functions of climate, soil, and very critically, of crop sensitivity and the actual salinity of the irrigation water. The more sensitive the crop and more saline the water, the higher the agronomic cost and the greater the quantitative need for leaching. Israel is a forerunner in large-scale utilization of poor quality water for irrigation and can be used as a case study looking at long term repercussions of policy alternatively encouraging irrigation with recycled water or brackish groundwater. In cases studied in desert conditions of Israel, as much of half of the water applied to crops including bell peppers in greenhouses and date palms is actually used to leach salts from the root zone. The excess water used to leach salts and maintain agronomic and economic success when irrigating with water containing salts can become an environmental hazard, especially in dry areas where natural drainage is non-existent. The leachate often contains not only salts but also agrochemicals including nutrients, and natural contaminants can be picked up and transported as well. This leachate passes beyond the root zone and eventually reaches ground or surface water resources. This, together with evidence of ongoing increases in sodium content of fresh produce and increased SAR levels of soils, suggest that the current policy and practice in Israel of utilization of high amounts of low quality irrigation water is inherently non- sustainable. Current

75 FR 61467 - Desert Southwest Power, LLC; Notice of Filing

Federal Register 2010, 2011, 2012, 2013, 2014

2010-10-05

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. EL10-54-000] Desert Southwest Power, LLC; Notice of Filing September 27, 2010. Take notice that on September 24, 2010, Desert Southwest Power, LLC (Desert Southwest) supplemented the responses filed on September 10, 2010 with...

75 FR 57761 - Desert Southwest Power, LLC; Notice of Filing

Federal Register 2010, 2011, 2012, 2013, 2014

2010-09-22

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. EL10-54-000] Desert Southwest Power, LLC; Notice of Filing September 14, 2010. Take notice that on September 10, 2010, Desert Southwest Power, LLC (Desert Southwest) filed responses to the Federal Energy Regulatory Commission's...

Use of inpatient psychiatric services on a U.S. Army combat support post during Operations Desert Shield and Desert Storm: the stress of non-deployment.

PubMed

Koshes, R J; Rothberg, J M

1994-06-01

We studied the utilization of inpatient psychiatric services during Operations Desert Shield and Desert Storm (the Persian Gulf War of 1990-1991) on a U.S. Army combat support post. Inpatient psychiatric admissions and dispositions for the post's catchment area were tallied before, during, and after Operations Desert Shield and Desert Storm. Subjects included active duty soldiers (deployed soldiers were not studied while they were away from the post), their families, and retirees. Overall, there was no increase in psychiatric hospitalizations for active duty soldiers, their family members, or retirees. However, coincident with the return of soldiers from Operations Desert Shield and Desert Storm, the psychiatric proportion of all hospitalizations increased in the subpopulation of soldiers not deployed who had served less than 1 year. These soldiers in training may be more susceptible to increased stress levels associated with the return of soldiers from war because of their inadequate group bonding.

Molten Salt Synthesis and High Rate Performance of the ‘‘Desert-Rose’’ form of LiCoO2

DOE Office of Scientific and Technical Information (OSTI.GOV)

H Chen; C Grey

2011-12-31

The synthesis of a novel nanostructure of LiCoO{sub 2}, and its performance as a cathode for a high-rate lithium ion battery, is described. The LiCoO{sub 2} nanostructure resembles the morphology of a known natural mineral: 'desert rose' gypsum. A range of measurement techniques are used to investigate the growth mechanism of this structure and the origin of its high rate charge/discharge properties.

Soil microbial diversity, site conditions, shelter forest land, saline water drip-irrigation, drift desert.

PubMed

Jin, Zhengzhong; Lei, Jiaqiang; Li, Shengyu; Xu, Xinwen

2013-10-01

Soil microbes in forest land are crucial to soil development in extreme areas. In this study, methods of conventional culture, PLFA and PCR-DGGE were utilized to analyze soil microbial quantity, fatty acids and microbial DNA segments of soils subjected to different site conditions in the Tarim Desert Highway forest land. The main results were as follows: the soil microbial amount, diversity indexes of fatty acid and DNA segment differed significantly among sites with different conditions (F < F0.05 ). Specifically, the values were higher in the middle and base of dunes than the top part of dunes and hardened flat sand, but all values for dunes were higher than for drift sand. Bacteria was dominant in the soil microbial community (>84%), followed by actinomycetes and then fungi (<0.05%). Vertical differences in the soil microbial diversity were insignificant at 0-35 cm. Correlation analysis indicated that the forest trees grew better as the soil microbial diversity index increased. Therefore, construction of the Tarim Desert Highway shelter-forest promoted soil biological development; however, for enhancing sand control efficiency and promoting sand development, we should consider the effects of site condition in the construction and regeneration of shelter-forest ecological projects. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Desert tortoise (Gopherus agassizii): Status-of-knowledge outline with references

Treesearch

Mark C. Grover; Lesley A. DeFalco

1995-01-01

Provides an overview of extant desert tortoise literature, summarizing literature on taxonomy, morphology, genetics, and paleontology and paleoecology of the desert tortoise, as well as its general ecology. Literature on desert tortoise ecology encompasses distribution and habitat, burrows and dens, reproduction, growth, physiology, feeding and nutrition, mortality...

Tree rings record 100 years of hydrologic change within a wetland

USGS Publications Warehouse

Yanosky, Thomas M.; Kappel, William M.

1997-01-01

Hydrology and tree growth were investigated within a small wetland in the Tully Valley of central New York, about 20 miles south of Syracuse. In late 1994 it was noted that some wetland trees were dying, and local residents reported that flow of a small stream draining the wetland seemingly increased and became more brackish since the mid to late 1980s. The wetland is about 3 miles north of an extensive salt mining operation known to have degraded local water quality, but no effects of mining had been confirmed previously near the wetland. The oldest wetland trees started to grow before the onset of mining in 1889, and thus tree-ring studies were undertaken not only to investi-gate recent hydrologic change within the wetland, but also to search for evidence of any other changes during the last 100 years.

Leaf conductance and carbon gain under salt-stressed conditions

NASA Astrophysics Data System (ADS)

Volpe, V.; Manzoni, S.; Marani, M.; Katul, G.

2011-12-01

Exposure of plants to salt stress is often accompanied by reductions in leaf photosynthesis and in stomatal and mesophyll conductances. To separate the effects of salt stress on these quantities, a model based on the hypothesis that carbon gain is maximized subject to a water loss cost is proposed. The optimization problem of adjusting stomatal aperture for maximizing carbon gain at a given water loss is solved for both a non-linear and a linear biochemical demand function. A key novel theoretical outcome of the optimality hypothesis is an explicit relationship between the stomatal and mesophyll conductances that can be evaluated against published measurements. The approaches here successfully describe gas-exchange measurements reported for olive trees (Olea europea L.) and spinach (Spinacia oleraceaL.) in fresh water and in salt-stressed conditions. Salt stress affected both stomatal and mesophyll conductances and photosynthetic efficiency of both species. The fresh water/salt water comparisons show that the photosynthetic capacity is directly reduced by 30%-40%, indicating that reductions in photosynthetic rates under increased salt stress are not due only to a limitation of CO2diffusion. An increase in salt stress causes an increase in the cost of water parameter (or marginal water use efficiency) exceeding 100%, analogous in magnitude to findings from extreme drought stress studies. The proposed leaf-level approach can be incorporated into physically based models of the soil-plant-atmosphere system to assess how saline conditions and elevated atmospheric CO2 jointly impact transpiration and photosynthesis.

Status and habitat relationships of northern flying squirrels on Mount Desert Island, Maine

USGS Publications Warehouse

O'Connell, A.F.; Servello, F.; Higgins, J.; Halteman, W.

2001-01-01

Northern (Glaucomys sabrinus) and southern (G. volans) flying squirrels occur in Maine, but there is uncertainty about range overlap in southcentral Maine where the southern flying squirrel reaches its geographic range limit. We surveyed flying squirrels on Mount Desert Island (MDI), located along the central Maine coast, to update the current status and distribution of these species. We captured only northern flying squirrels, and populations (> 2 individuals) were located in two conifer stands and one mixed conifer-hardwood stand. All three stands were located in relatively older forests, outside a large area burned in a 1947 fire. Tree diameters were similar between trap stations with and without captures, under-story density was low overall, and there was a trend of higher seedling density at capture locations. Low understory density may allow squirrels more effective gliding movements between trees, which may enhance predator avoidance. Although the southern flying squirrel was reported from MDI numerous times during the 20th century, no voucher specimens exist, and species identification and localities have been poorly documented. Future surveys on MDI should consider collection of voucher specimens to validate subsequent survey efforts and effectively document changes in local biodiversity.

Hominin Dispersal into the Nefud Desert and Middle Palaeolithic Settlement along the Jubbah Palaeolake, Northern Arabia

PubMed Central

Petraglia, Michael D.; Alsharekh, Abdullah; Breeze, Paul; Clarkson, Chris; Crassard, Rémy; Drake, Nick A.; Groucutt, Huw S.; Jennings, Richard; Parker, Adrian G.; Parton, Ash; Roberts, Richard G.; Shipton, Ceri; Matheson, Carney; al-Omari, Abdulaziz; Veall, Margaret-Ashley

2012-01-01

The Arabian Peninsula is a key region for understanding hominin dispersals and the effect of climate change on prehistoric demography, although little information on these topics is presently available owing to the poor preservation of archaeological sites in this desert environment. Here, we describe the discovery of three stratified and buried archaeological sites in the Nefud Desert, which includes the oldest dated occupation for the region. The stone tool assemblages are identified as a Middle Palaeolithic industry that includes Levallois manufacturing methods and the production of tools on flakes. Hominin occupations correspond with humid periods, particularly Marine Isotope Stages 7 and 5 of the Late Pleistocene. The Middle Palaeolithic occupations were situated along the Jubbah palaeolake-shores, in a grassland setting with some trees. Populations procured different raw materials across the lake region to manufacture stone tools, using the implements to process plants and animals. To reach the Jubbah palaeolake, Middle Palaeolithic populations travelled into the ameliorated Nefud Desert interior, possibly gaining access from multiple directions, either using routes from the north and west (the Levant and the Sinai), the north (the Mesopotamian plains and the Euphrates basin), or the east (the Persian Gulf). The Jubbah stone tool assemblages have their own suite of technological characters, but have types reminiscent of both African Middle Stone Age and Levantine Middle Palaeolithic industries. Comparative inter-regional analysis of core technology indicates morphological similarities with the Levantine Tabun C assemblage, associated with human fossils controversially identified as either Neanderthals or Homo sapiens. PMID:23185454

43 CFR 2524.6 - Desert-land entryman may proceed independently of Government irrigation.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 43 Public Lands: Interior 2 2013-10-01 2013-10-01 false Desert-land entryman may proceed... (2000) DESERT-LAND ENTRIES Desert-Land Entries Within a Reclamation Project § 2524.6 Desert-land... that a desert-land entryman who owns a water right and reclaims the land embraced in his entry must...

43 CFR 2524.6 - Desert-land entryman may proceed independently of Government irrigation.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 43 Public Lands: Interior 2 2012-10-01 2012-10-01 false Desert-land entryman may proceed... (2000) DESERT-LAND ENTRIES Desert-Land Entries Within a Reclamation Project § 2524.6 Desert-land... that a desert-land entryman who owns a water right and reclaims the land embraced in his entry must...

43 CFR 2524.6 - Desert-land entryman may proceed independently of Government irrigation.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 43 Public Lands: Interior 2 2011-10-01 2011-10-01 false Desert-land entryman may proceed... (2000) DESERT-LAND ENTRIES Desert-Land Entries Within a Reclamation Project § 2524.6 Desert-land... that a desert-land entryman who owns a water right and reclaims the land embraced in his entry must...

43 CFR 2524.6 - Desert-land entryman may proceed independently of Government irrigation.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 43 Public Lands: Interior 2 2014-10-01 2014-10-01 false Desert-land entryman may proceed... (2000) DESERT-LAND ENTRIES Desert-Land Entries Within a Reclamation Project § 2524.6 Desert-land... that a desert-land entryman who owns a water right and reclaims the land embraced in his entry must...

Nest desertion and cowbird parasitism: evidence for evolved responses and evolutionary lag.

PubMed

Hosoi; Rothstein

2000-04-01

Nest desertion with subsequent renesting is a frequently cited response to parasitism by the brown-headed cowbird, Molothrus ater, yet the role of desertion as an antiparasite defence is widely debated. To determine whether desertion represents an evolutionary response to brown-headed cowbird parasitism, we searched the primary literature, yielding data on the desertion frequencies of 60 host populations from 35 species. Species were categorized according to three habitat types (forest, intermediate and nonforest). Because cowbirds prefer open habitat and rarely penetrate deeply into forests, nonforest species have long been exposed to widespread cowbird parasitism, whereas forest species have not. However, due to increased forest fragmentation, forest species are being increasingly exposed to extensive parasitism. The frequency of desertion of parasitized nests was significantly higher in nonforest than forest species, suggesting that the latter experience evolutionary lag. We also considered whether desertion is affected by predation frequency, degree of current or recent sympatry with cowbirds, parasitism frequency, length of host laying season, phylogenetic relationships, and potential cost of cowbird parasitism. None of these variables created biases that could account for the observed difference in desertion frequencies of nonforest and forest species. However, species that incur large costs when parasitized had higher desertion rates among nonforest species but not among forest species. These results indicate that increased nest desertion is an evolved response to cowbird parasitism, as one would otherwise expect no relationship between desertion frequency and thezx costs and length of exposure to cowbird parasitism. Although nearly all hosts have eggs easily distinguished from cowbird eggs, few or none desert in response to cowbird eggs. Instead, desertion may be a response to adult cowbirds. The scarcity of species that desert in response to cowbird eggs

Inferences about winter temperatures and summer rains from the late Quaternary record of C4 perennial grasses and C3 desert shrubs in the northern Chihuahuan Desert

USGS Publications Warehouse

Holmgren, Camille A.; Norris, Jodi; Betancourt, Julio L.

2007-01-01

Late Quaternary histories of two North American desert biomes—C4 grasslands and C3 shrublands—are poorly known despite their sensitivity and potential value in reconstructing summer rains and winter temperatures. Plant macrofossil assemblages from packrat midden series in the northern Chihuahuan Desert show that C4 grasses and annuals typical of desert grassland persisted near their present northern limits throughout the last glacial-interglacial cycle. By contrast, key C3 desert shrubs appeared somewhat abruptly after 5000cal.yrBP. Bioclimatic envelopes for select C4 and C3 species are mapped to interpret the glacial-interglacial persistence of desert grassland and the mid-to-late Holocene expansion of desert shrublands. The envelopes suggest relatively warm Pleistocene temperatures with moist summers allowed for persistence of C4 grasses, whereas winters were probably too cold (or too wet) for C3 desert shrubs. Contrary to climate model results, core processes associated with the North American Monsoon and moisture transport to the northern Chihuahuan Desert remained intact throughout the last glacial-interglacial cycle. Mid-latitude effects, however, truncated midsummer (July-August) moisture transport north of 35° N. The sudden expansion of desert shrublands after 5000cal.yrBP may be a threshold response to warmer winters associated with increasing boreal winter insolation, and enhanced El Niño-Southern Oscillation variability.

Desert pavement study at Amboy, California

NASA Technical Reports Server (NTRS)

Williams, S.; Greeley, R.

1984-01-01

Desert pavement is a general term describing a surface that typically consists of a thin layer of cm-sized rock fragments set on top of a layer of finer material in which no fragments are found. An understanding of desert pavement is important to planetary geology because they may play a major role in the formation and visibility of various aeolian features such as wind streaks, which are important on Mars and may be important on Venus. A field study was conducted in Amboy, California to determine the formation mechanism of desert pavements. The probable sequence of events for the formation and evolution of a typical desert pavement surface, based on this experiment and the work of others, is as follows. Starting with a layer of surface material consisting of both fine particles and rock fragments, aeolian deflation will rapidly erode the surface until an armored lag is developed, after which aeolian processes become less important. The concentration of fragments then slowly increases as new fragments are brought to the surface from the subsurface and as fragments move downslope by sheet wash. Sheet wash would be responsible for removing very fine particles from the surface and for moving the fragments relative to one another, forming interlocks.

Oxalosis in wild desert tortoises, Gopherus agassizii

USGS Publications Warehouse

Jacobson, Elliott R.; Berry, Kristin H.; Stacy, Brian; Huzella, Louis M.; Kalasinsky, Victor F.; Fleetwood, Michelle L.; Mense, Mark G.

2009-01-01

We necropsied a moribund, wild adult male desert tortoise (Gopherus agassizii) with clinical signs of respiratory disease and elevated plasma biochemical analytes indicative of renal disease (blood urea nitrogen [415 mg/dl], uric acid [11.8 mg/dl], sodium >180 mmol/l] and chloride [139 mmol/l]). Moderate numbers of birefringent oxalate crystals, based on infrared and electron microscopy, were present within renal tubules; small numbers were seen in colloid within thyroid follicles. A retrospective analysis of 66 additional cases of wild desert tortoises was conducted to determine whether similar crystals were present in thyroid and kidney. The tortoises, from the Mojave and Sonoran deserts, were necropsied between 1992 and 2003 and included juveniles and adults. Tortoises were classified as healthy (those that died due to trauma and where no disease was identified after necropsy and evaluation by standard laboratory tests used for other tortoises) or not healthy (having one or more diseases or lesions). For all 67 necropsied tortoises, small numbers of crystals of similar appearance were present in thyroid glands from 44 of 54 cases (81%) and in kidneys from three of 65 cases (5%). Presence of oxalates did not differ significantly between healthy and unhealthy tortoises, between age classes, or between desert region, and their presence was considered an incidental finding. Small numbers of oxalate crystals seen within the kidney of two additional tortoises also were considered an incidental finding. Although the source of the calcium oxalate could not be determined, desert tortoises are herbivores, and a plant origin seems most likely. Studies are needed to evaluate the oxalate content of plants consumed by desert tortoises, and particularly those in the area where the tortoise in renal failure was found.

The heat is on: Desert tortoises and survival

USGS Publications Warehouse

Wessells, Stephen M.; Schwarzbach, Steven E.

2010-01-01

Purpose: To highlight USGS scientists' research and build support for the work being done to help with desert tortoise recovery. To educate people about desert tortoises, their habitat needs, and what people might do to help. Length: 30 minutes

ZZYZX--The Last Word in Desert Studies

ERIC Educational Resources Information Center

Hill, Martin

1977-01-01

The mineral springs resort of Zzyzx in California is the site of a unique academic research center in high desert studies. It is being developed into a Desert Studies Center for seven southern campuses of the California State University and College System, and will provide field work opportunities for geology, geography, and anthropology students.…

75 FR 19246 - Safety Zone; Desert Storm, Lake Havasu, AZ

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-14

...-AA00 Safety Zone; Desert Storm, Lake Havasu, AZ AGENCY: Coast Guard, DHS. ACTION: Temporary final rule... navigable waters of the Colorado River in Lake Havasu, Lake Havasu City, Arizona in support of the Desert.... Background and Purpose The Lake Racer LLC is sponsoring the Desert Storm Charity Poker Run and Exhibition Run...

Role of Nitric Oxide in the Regulation of Renin and Vasopressin Secretion

NASA Technical Reports Server (NTRS)

Reid, Ian A.

1994-01-01

Research during recent years has established nitric oxide as a unique signaling molecule that plays important roles in the regulation of the cardiovascular, nervous, immune, and other systems. Nitric oxide has also been implicated in the control of the secretion of hormones by the pancreas, hypothalamus, and anterior pituitary gland, and evidence is accumulating that it contributes to the regulation of the secretion of renin and vasopressin, hormones that play key roles in the control of sodium and water balance. Several lines of evidence have implicated nitric oxide in the control of renin secretion. The enzyme nitric oxide synthase is present in vascular and tubular elements of the kidney, particularly in cells of the macula densa, a structure that plays an important role in the control of renin secretion. Guanylyl cyclase, a major target for nitric oxide, is also present in the kidney. Drugs that inhibit nitric oxide synthesis generally suppress renin release in vivo and in vitro, suggesting a stimulatory role for the L-arginine/nitric oxide pathway in the control of renin secretion. Under some conditions, however, blockade of nitric oxide synthesis increases renin secretion. Recent studies indicate that nitric oxide not only contributes to the regulation of basal renin secretion, but also participates in the renin secretory responses to activation of the renal baroreceptor, macula densa, and beta adrenoceptor mechanisms that regulate renin secretion. Histochemical and immunocytochemical studies have revealed the presence of nitric oxide synthase in the supraoptic and paraventricular nuclei of the hypothalamus and in the posterior pituitary gland. Colocalization of nitric oxide synthase and vasopressin has been demonstrated in some hypothalamic neurons. Nitric oxide synthase activity in the hypothalamus and pituitary is increased by maneuvers known to stimulate vasopressin secretion, including salt loading and dehydration, Administration of L-arginine and nitric

Tree mortality in mature riparian forest: Implications for Fremont cottonwood conservation in the American southwest

USGS Publications Warehouse

Andersen, Douglas

2015-01-01

Mature tree mortality rates are poorly documented in desert riparian woodlands. I monitored deaths and calculated annual survivorship probability (Ps) in 2 groups of large (27–114 cm DBH), old (≥40 years old) Fremont cottonwood (Populus fremontii Wats.) in a stand along the free-flowing Yampa River in semiarid northwestern Colorado. Ps = 0.993 year-1 in a group (n = 126) monitored over 2003–2013, whereas Ps = 0.985 year-1 in a group (n = 179) monitored over the same period plus 3 earlier years (2000–2003) that included drought and a defoliating insect outbreak. Assuming Ps was the same for both groups during the 10-year postdrought period, the data indicate that Ps = 0.958 year-1 during the drought. I found no difference in canopy dieback level between male and female survivors. Mortality was equal among size classes, suggesting Ps is independent of age, but published longevity data imply that either Ps eventually declines with age or, as suggested in this study, periods with high Ps are interrupted by episodes of increased mortality. Stochastic population models featuring episodes of low Ps suggest a potential for an abrupt decline in mature tree numbers where recruitment is low. The modeling results have implications for woodland conservation, especially for relictual stands along regulated desert rivers.

Salt-Induced Physical Weathering of Stone

NASA Astrophysics Data System (ADS)

Schiro, M.; Ruiz-Agudo, E.; Rodriguez-Navarro, C.

2010-12-01

Salt weathering is recognized as an important mechanism that contributes to the modeling and shaping of the earth’s surface, in a range of environments spanning from the Sahara desert to Antarctica. It also contributes to the degradation and loss of cultural heritage, particularly carved stone and historic buildings. Soluble salts have recently been suggested to contribute to the shaping of rock outcrops on Mars and are being identified in other planetary bodies such as the moons of Jupiter (Europa and IO)1. Soluble salts such as sulfates, nitrates, chlorides and carbonates of alkali and alkali earth metals can crystallize within the porous system of rocks and building stones, exerting sufficient pressure against the pore walls to fracture the substrate. This physical damage results in increased porosity, thus providing a higher surface area for salt-enhanced chemical weathering. To better understand how salt-induced physical weathering occurs, we have studied the crystallization of the particularly damaging salt, sodium sulfate2, in a model system (a sintered porous glass of controlled porosity and pore size). For this elusive task of studying sub-surface crystallization in pores, we combined a variety of instruments to identify which phases crystallized during evaporation and calculated the supersaturation and associated crystallization pressure that caused damage. The heat of crystallization was measured using differential scanning calorimetry (DSC), providing the timing of crystallization events and phase transitions3, while the evaporation rate was recorded using thermal gravimetry (TG). These methods enabled calculation of the sodium sulfate concentration in solution at every point during evaporation. Two-dimensional X-ray diffraction (2D-XRD) performs synchrotron-like experiments in a normal lab by using a Molybdenum X-ray source (more than 5 times more penetrative than conventional Copper source). Using this method, we determined that the first phase to

43 CFR 2521.1 - Who may make desert-land entry.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 43 Public Lands: Interior 2 2012-10-01 2012-10-01 false Who may make desert-land entry. 2521.1... MANAGEMENT, DEPARTMENT OF THE INTERIOR LAND RESOURCE MANAGEMENT (2000) DESERT-LAND ENTRIES Procedures § 2521.1 Who may make desert-land entry. (a) Citizenship. (1) Any citizen of the United States 21 years of...

43 CFR 2521.1 - Who may make desert-land entry.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 43 Public Lands: Interior 2 2014-10-01 2014-10-01 false Who may make desert-land entry. 2521.1... MANAGEMENT, DEPARTMENT OF THE INTERIOR LAND RESOURCE MANAGEMENT (2000) DESERT-LAND ENTRIES Procedures § 2521.1 Who may make desert-land entry. (a) Citizenship. (1) Any citizen of the United States 21 years of...

43 CFR 2521.1 - Who may make desert-land entry.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 43 Public Lands: Interior 2 2011-10-01 2011-10-01 false Who may make desert-land entry. 2521.1... MANAGEMENT, DEPARTMENT OF THE INTERIOR LAND RESOURCE MANAGEMENT (2000) DESERT-LAND ENTRIES Procedures § 2521.1 Who may make desert-land entry. (a) Citizenship. (1) Any citizen of the United States 21 years of...

43 CFR 2521.1 - Who may make desert-land entry.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 43 Public Lands: Interior 2 2013-10-01 2013-10-01 false Who may make desert-land entry. 2521.1... MANAGEMENT, DEPARTMENT OF THE INTERIOR LAND RESOURCE MANAGEMENT (2000) DESERT-LAND ENTRIES Procedures § 2521.1 Who may make desert-land entry. (a) Citizenship. (1) Any citizen of the United States 21 years of...

Desert dust outbreaks and respiratory morbidity in Athens, Greece.

PubMed

Trianti, Stavroula-Myrto; Samoli, Evangelia; Rodopoulou, Sophia; Katsouyanni, Klea; Papiris, Spyros A; Karakatsani, Anna

2017-07-01

Ambient particulate matter (PM) has an adverse effect on respiratory morbidity. Desert dust outbreaks contribute to increased PM levels but the toxicity of desert dust mixed with anthropogenic pollutants needs clarification. We identified 132 days with desert dust episodes and 177 matched days by day of the week, season, temperature and humidity between 2001 and 2006 in Athens, Greece. We collected data on regulated pollutants and daily emergency outpatient visits and admissions for respiratory causes. We applied Poisson regression models adjusting for confounding effects of seasonality, meteorology, holidays and influenza epidemics. We evaluated the sensitivity of our results to co-pollutant exposures and effect modification by age and sex. A 10 μg/m 3 increase in PM 10 concentration was associated with 1.95% (95% confidence interval (CI): 0.02%, 3.91%) increase in respiratory emergency room visits. No significant interaction with desert dust episodes was observed. Compared with non-dust days, there was a 47% (95% CI: 29%, 68%) increase in visits in dust days not adjusting for PM 10 . Desert dust days were associated with higher numbers of emergency room visits for asthma, chronic obstructive pulmonary disease and respiratory infections with increases of 38%, 57% and 60%, respectively (p < 0.001 for all comparisons). Analyses of respiratory hospital admissions provided similar results. PM 10 effects decreased when adjusting for desert dust days and were further confounded by co-pollutants. Desert dust episode days are associated with higher respiratory emergency room visits and hospital admissions. This effect is insufficiently explained by increased PM 10 levels.

Quaternary climate change on the northern margins of Saharo-Arabian Desert with possible impact on human evolution, evidence from Negev Desert speleothems, Israel

NASA Astrophysics Data System (ADS)

Vaks, A.; Bar-Matthews, M.; Ayalon, A.; Matthews, A.; Halicz, L.; Frumkin, A.

2006-12-01

The Saharo-Arabian Desert belt is the largest and driest desert in the world and its margins are vulnerable to climatic change. The paleoclimate of the northern margins of Saharo-Arabian Desert is not yet fully understood, and it is the subject of our study. The Negev Desert, southern Israel, located in the northern part of the Saharo-Arabian Desert is ideal for paleoclimate research, because of its very steep north-south precipitation gradient and numerous caves rich with carbonate cave deposits (speleothems). Speleothems grow only when precipitation is high enough to enable meteoric water to reach the caves. No present day speleothem deposition occurs in the Negev Desert. The aims of the study were: timing of the humid periods by U-Th dating of the speleothem deposition periods; origin of the rainfall by speleothem δ18O and fluid inclusions δ2H; correlations between local and global climate changes and between the climate changes to out of Africa dispersals of Early Modern Humans (EMH). Speleothems were collected from 7 caves located on the north-south transect of the Negev Desert, between 300 mm to 30 mm isohyets. Whereas in the Mediterranean climate zone (>350 mm) of central and northern Israel the speleothem deposition was continuous, in the Negev Desert periods of speleothem deposition alternated with multiple hiatuses. In the mildly arid transition zone of northern Negev (300 to 150 mm) speleothem deposition occurred most of the time during the last 210 ka, with hiatuses at 150-144 ka, ~140 ka, 117-96 ka, 93-85 ka, 25- 23 ka, and 14-0 ka. In present-day arid and hyper-arid zone of central and southern Negev (150 to 30 mm) no speleothem deposition occurred most of the last 350 ka, with humid intervals at 350-290 ka, 220-190 ka, 137- 110 ka, and ~85 ka. The origin of the precipitation in the Negev Desert during these intervals was from Eastern Mediterranean Sea, i. e. mid-latitude cyclones (as present day). The latter conclusion is based on three evidences

Influence of Acacia trees on soil nutrient levels in arid lands

NASA Astrophysics Data System (ADS)

De Boever, Maarten; Gabriels, Donald; Ouessar, Mohamed; Cornelis, Wim

2014-05-01

The potential of scattered trees as keystone structures in restoring degraded environments is gaining importance. Scattered trees have strong influence on their abiotic environment, mainly causing changes in microclimate, water budget and soil properties. They often function as 'nursing trees', facilitating the recruitment of other plants. Acacia raddiana is such a keystone species which persists on the edge of the Sahara desert. The study was conducted in a forest-steppe ecosystem in central Tunisia where several reforestation campaigns with Acacia took place. To indentify the impact of those trees on soil nutrients, changes in nutrient levels under scattered trees of three age stages were examined for the upper soil layer (0-10 cm) at five microsites with increasing distance from the trunk. In addition, changes in soil nutrient levels with depth underneath and outside the canopy were determined for the 0-30 cm soil layer. Higher concentrations of organic matter (OM) were found along the gradient from underneath to outside the canopy for large trees compared to medium and small trees, especially at microsites close to the trunk. Levels of soluble K, electrical conductivity (EC), available P, OM, total C and N decreased whereas pH and levels of soluble Mg increased with increasing distance from tree. Levels of soluble Ca and Na remained unchanged along the gradient. At the microsite closest to the trunk a significant decrease in levels of soluble K, EC, OM, available P, total C and N, while a significant increase in pH was found with increasing depth. The concentration of other nutrients remained unchanged or declined not differently underneath compared to outside the canopy with increasing depth. Differences in nutrient levels were largely driven by greater inputs of organic matter under trees. Hence, Acacia trees can affect the productivity and reproduction of understory species with the latter in term an important source of organic matter. This positive feedback

An Economic View of Food Deserts in the United States

ERIC Educational Resources Information Center

Bitler, Marianne; Haider, Steven J.

2011-01-01

Considerable policy and academic attention has been focused on the topic of food deserts. We consider this topic from an economic perspective. First, we consider how the components of a standard economic analysis apply to the study of food deserts. Second, using this economic lens, we revisit the empirical literature on food deserts to assess the…

Cerebral salt-wasting syndrome due to hemorrhagic brain infarction: a case report.

PubMed

Tanaka, Tomotaka; Uno, Hisakazu; Miyashita, Kotaro; Nagatsuka, Kazuyuki

2014-07-23

Cerebral salt-wasting syndrome is a condition featuring hyponatremia and dehydration caused by head injury, operation on the brain, subarachnoid hemorrhage, brain tumor and so on. However, there are a few reports of cerebral salt-wasting syndrome caused by cerebral infarction. We describe a patient with cerebral infarction who developed cerebral salt-wasting syndrome in the course of hemorrhagic transformation. A 79-year-old Japanese woman with hypertension and arrhythmia was admitted to our hospital for mild consciousness disturbance, conjugate deviation to right, left unilateral spatial neglect and left hemiparesis. Magnetic resonance imaging revealed a broad ischemic change in right middle cerebral arterial territory. She was diagnosed as cardiogenic cerebral embolism because atrial fibrillation was detected on electrocardiogram on admission. She showed hyponatremia accompanied by polyuria complicated at the same time with the development of hemorrhagic transformation on day 14 after admission. Based on her hypovolemic hyponatremia, she was evaluated as not having syndrome of inappropriate secretion of antidiuretic hormone but cerebral salt-wasting syndrome. She fortunately recovered with proper fluid replacement and electrolyte management. This is a rare case of cerebral infarction and cerebral salt-wasting syndrome in the course of hemorrhagic transformation. It may be difficult to distinguish cerebral salt-wasting syndrome from syndrome of inappropriate antidiuretic hormone, however, an accurate assessment is needed to reveal the diagnosis of cerebral salt-wasting syndrome because the recommended fluid management is opposite in the two conditions.

Oxalate secretion by ectomycorrhizal Paxillus involutus is mineral-specific and controls calcium weathering from minerals

PubMed Central

Schmalenberger, A.; Duran, A. L.; Bray, A. W.; Bridge, J.; Bonneville, S.; Benning, L. G.; Romero-Gonzalez, M. E.; Leake, J. R.; Banwart, S. A.

2015-01-01

Trees and their associated rhizosphere organisms play a major role in mineral weathering driving calcium fluxes from the continents to the oceans that ultimately control long-term atmospheric CO2 and climate through the geochemical carbon cycle. Photosynthate allocation to tree roots and their mycorrhizal fungi is hypothesized to fuel the active secretion of protons and organic chelators that enhance calcium dissolution at fungal-mineral interfaces. This was tested using 14CO2 supplied to shoots of Pinus sylvestris ectomycorrhizal with the widespread fungus Paxillus involutus in monoxenic microcosms, revealing preferential allocation by the fungus of plant photoassimilate to weather grains of limestone and silicates each with a combined calcium and magnesium content of over 10 wt.%. Hyphae had acidic surfaces and linear accumulation of weathered calcium with secreted oxalate, increasing significantly in sequence: quartz, granite < basalt, olivine, limestone < gabbro. These findings confirmed the role of mineral-specific oxalate exudation in ectomycorrhizal weathering to dissolve calcium bearing minerals, thus contributing to the geochemical carbon cycle. PMID:26197714

Stable Ca Isotopes in Tamarix aphylla Tree Rings, Death Valley, California

NASA Astrophysics Data System (ADS)

Yang, W.; Depaolo, D. J.; Ingram, B. L.; Owens, T. L.

2008-12-01

As a dune stabilizer and windbreak, Tamarix aphylla is an exotic perennial and evergreen tree in Death Valley. Its tap roots can reach down to 30 m depth and sub-superficial side roots may reach 50 m horizontally. The species can store large amounts of water in its roots and undergoes high evapotranspiration. Since Tamarix aphylla is a perennial tree growing in desert environments and its roots reach deep to the water table, it could be a proxy for desert ecological and hydrologic systems through time. We measured Ca isotopes in the soluble fraction of 8 tree ring samples from a 50-year-old specimen growing on an alluvial fan in Death Valley near Furnace Creek. Previous studies (Yang et al, GCA 60, 1996) indicate that this tree's rings contain high sulfur concentrations (4-6% expressed as sulfate) with chemical composition of CaSO4 (0.15-0.62 H2O). The δ34S values of soluble sulfate increase from +13.5 to +18 permil VCDT from the core to the bark, which are interpreted as reflecting deeper sulfate sources as the tree grew. The δ13C variations of the tree-ring cellulose (-27.6 to -24.0 permil VPDB) reflect changes in the local precipitation and show that Tamarix aphylla undergoes C3 photosynthesis. The δ44Ca for the soluble sulfate Ca through the tree-ring section, which covers a time period from 1945 to 1993, have an average value -2.52 permil (-3.4 permil relative to seawater). Only small variations are observed, from -2.69 to -2.28; the highest value (for 1990) occurs near the end of an extended drought. These are the first measurements of tree rings, but the low δ44Ca values are consistent with previous measurements of beech roots and stems from a temperate forest (Page et al., Biogeochem. 88, 2008). In our case, the tree has only one Ca source, which is expected to be isotopically uniform and similar to both local rainfall and limestones (δ44Ca ~ -0.6 permil), and with the minimal vegetation and extensive deep root system it is unlikely that there is a

Desert Pavement Process and Form: Modes and Scales of Landscape Stability and Instability in Arid Regions

NASA Astrophysics Data System (ADS)

Wells, Stephen G.; McFadden, Leslie D.; McDonald, Eric V.; Eppes, Martha C.; Young, Michael H.; Wood, Yvonne A.

2014-05-01

Desert pavements are recognized in arid landscapes around the world, developing via diminution of constructional/depositional landform relief and creating a 1-2 stone thick armor over a "stone free" layer. Surface exposure dating demonstrates that clasts forming the desert pavements are maintained at the land surface over hundreds of thousands of years, as aeolian fines are deposited on the land surface, transported into the underlying parent material and incorporated into accretionary soil horizons (e.g., the stone free or vesicular [Av] horizon). This surface armor provides long-term stability over extensive regions of the landscape. Over shorter time periods and at the landform-element scale, dynamic surficial processes (i.e., weathering, runoff) continue to modify the pavement form. Clast size reduction in comparison to underlying parent material, along with armoring and packing of clasts in pavements contribute to their persistence, and studies of crack orientations in pavement clasts indicate physical weathering and diminution of particle size are driven by diurnal solar insolation. Over geologic time, cracks form and propagate from tensile stresses related to temporal and spatial gradients in temperature that evolve and rotate in alignment with the sun's rays. Observed multimodal nature of crack orientations appear related to seasonally varying, latitude-dependent temperature fields resulting from solar angle and weather conditions. Surface properties and their underlying soil profiles vary across pavement surfaces, forming a landscape mosaic and controlling surface hydrology, ecosystem function and the ultimate life-cycle of arid landscapes. In areas of well-developed pavements, surface infiltration and soluble salt concentrations indicate that saturated hydraulic conductivity of Av horizons decline on progressively older alluvial fan surfaces. Field observations and measurements from well-developed desert pavement surfaces landforms also yield

No Substitute for Going to the Field: Correcting Lidar DEMs in Salt Marshes

NASA Astrophysics Data System (ADS)

Renken, K.; Morris, J. T.; Lynch, J.; Bayley, H.; Neil, A.; Rasmussen, S.; Tyrrell, M.; Tanis, M.

2016-12-01

Models that forecast the response of salt marshes to current and future trends in sea level rise increasingly are used to guide management of these vulnerable ecosystems. Lidar-derived DEMs serve as the foundation for modeling landform change. However, caution is advised when using these DEMs as the starting point for models of salt marsh evolution. While broad vegetation class (i.e., young forest, old forest, grasslands, desert, etc.) has proven to be a significant predictor of vertical displacement error in terrestrial environments, differentiating error among different species or community types within the same ecosystem has received less attention. Salt marshes are dominated by monocultures of grass species and thus are an ideal environment to examine the within-species effect on lidar DEM error. We analyzed error of lidar DEMs using elevations from real-time kinematic (RTK) surveys in saltmarshes in multiple national parks and wildlife refuge areas from the mouth of the Chesapeake Bay to Massachusetts. Error of the lidar DEMs was sometimes large, on the order of 0.25 m, and varied significantly between sites because vegetation cover varies seasonally and lidar data was not always collected in the same season for each park. Vegetation cover and composition were used to explain differences between RTK elevations and lidar DEMs. This research underscores the importance of collecting RTK elevation data and vegetation cover data coincident with lidar data to produce correction factors specific to individual salt marsh sites.

A systematic review of food deserts, 1966-2007.

PubMed

Beaulac, Julie; Kristjansson, Elizabeth; Cummins, Steven

2009-07-01

"Food deserts," areas characterized by poor access to healthy and affordable food, may contribute to social and spatial disparities in diet and diet-related health outcomes. However, the extent to which food deserts exist is debated. We review the evidence for the existence of food deserts in socioeconomically disadvantaged areas. We conducted a systematic review of primary, quantitative, observational studies, published in English or French, that used geographic or market-basket approaches in high-income countries. The literature search included electronic and hand searches and peer-reviewed and grey literature from 1966 through 2007. We also contacted key researchers to identify other studies. We analyzed the findings and quality of the studies qualitatively. Forty-nine studies in 5 countries met inclusion criteria; the amount and consistency of the evidence varied by country. These studies were a mix of geographic and market-basket approaches, but the methodologic quality of studies and completeness of reported findings were mixed. We found clear evidence for disparities in food access in the United States by income and race. Findings from other high-income countries were sparse and equivocal. This review suggests that food deserts exist in the United States, where area-level deprivation compounds individual disadvantage. Evidence for the existence of food deserts in other high-income nations is weak.

Geometeorological data collected by the USGS Desert Winds Project at Desert Wells, Sonoran Desert, central-west Arizona, 1981 - 1996

USGS Publications Warehouse

Helm, Paula J.; Breed, Carol S.; Tigges, Richard; Creighton, Shawn

1998-01-01

The data in this report were obtained by instruments deployed on a GOES-satellite data collection station operated by the U.S. Geological Survey Desert Winds Project at Desert Wells (latitude 33° 42' 08" N, longitude 113° 48' 40" W), La Paz County, west-central Arizona. The elevation is 344 m (1,130 ft). From January 9, 1981 through May 31, 1995 the station recorded eight parameters: wind direction, wind speed, peak gust, air temperature, precipitation, humidity, barometric pressure, and soil temperature. On June 1, 1995, the station was upgraded by adding a SENSIT sand-flux sensor, which records grain impacts concurrently with wind speed and wind direction measurements. Included with the data is descriptive text on the geology, soils, climate, vegetation, and land use at the site, as well as text on data format, date retrieval software and instructions, and metadata

Heatstroke model for desert dry-heat environment and observed organ damage.

PubMed

ou Zhou, Ren; Liu, Jiang Wei; Zhang, Dong; Zhang, Qiong

2014-06-01

Heatstroke is one of the most common clinical emergencies. Heatstroke that occurred in a dry-heat environment such as desert is usually more seriously effective and often leads to death. However, the report of the pathophysiologic mechanisms about heatstroke in dry-heat environment of desert has not been seen. Our objectives are to establish a rat model of heatstroke of dry-heat environment of desert, to assess the different degrees of damage of organ, and to preliminarily discuss the mechanism of heatstroke in dry-heat environment of desert. The first step, we have established a rat heatstroke model of dry heat environment of desert. The second step, we have accessed changes in morphology and blood indicators of heatstroke rats in dry-heat environment of desert. The heatstroke rats have expressed the changing characteristics of mean arterial pressure, core temperature, and heart rate. The organ damage changed from mild to serious level, specifically in the morphology and blood enzymology parameters such as alanine aminotransferase, aspartate aminotransferase, creatinine, urea, uric acid, creatine kinase-MB, creatine kinase, and blood gas parameters such as base excess extracellular fluid and bicarbonate ions (HCO3-). We have successfully established the rat heatstroke model of dry-heat environment of desert. We have identified heatstroke rats that presented changing characteristics on physiological indicators and varying degrees of organ damage, which are aggravated by the evolution of heatstroke in dry-heat environment of desert. We have preliminarily discussed the mechanism of heatstroke in dry-heat environment of desert. Copyright © 2014 Elsevier Inc. All rights reserved.

The origin of sulphur in gypsum and dissolved sulphate in the Central Namib Desert, Namibia

NASA Astrophysics Data System (ADS)

Eckardt, F. D.; Spiro, B.

1999-02-01

This study investigates the sulphur source of gypsum sulphate and dissolved groundwater sulphate in the Central Namib Desert, home to one of Africa's most extensive gypsum (CaSO 4·2H 2O) accumulations. It investigates previously suggested sulphate precursors such as bedrock sulphides and decompositional marine biogenic H 2S and studies the importance of other potential sources in order to determine the origin of gypsum and dissolved sulphate in the region. An attempt has been made to sample all possible sulphur sources, pathways and types of gypsum accumulations in the Central Namib Desert. We have subjected those samples to sulphur isotopic analyses and have compiled existing results. In addition, ionic ratios of Cl/SO 4 are used to determine the presence of non-sea-salt (NSS) sulphur in groundwater and to investigate processes affecting groundwater sulphate. In contrast to previous work, this study proposes that the sulphur cycle, and the formation of gypsum, in the Namib Desert appears to be dominated by the deposition of atmospheric sulphates of phytoplanktonic origin, part of the primary marine production of the Benguela upwelling cells. The aerosol sulphates are subjected to terrestrial storage within the gypsum deposits on the hyper-arid gravel plain and are traceable in groundwater including coastal sabkhas. The hypothesis of decompositional marine biogenic H 2S or bedrock sulphide sources, as considered previously for the Namib Desert, cannot account for the widespread accumulation of gypsum in the region. The study area in the Central Namib Desert, between the Kuiseb and Omaruru rivers, features extensive gypsum accumulations in a ca. 50-70 km wide band, parallel to the shore. They consist of surficial or shallow pedogenic gypsum crusts in the desert pavement, hydromorphic playa or sabkha gypsum, as thin isolated pockets on bedrock ridges and as discrete masses of gypsum selenite along some faults. The sulphur isotopic values (δ 34S ‰CDT) of these

Salt

USGS Publications Warehouse

Franson, J.C.; Friend, M.

1999-01-01

Animals become victims of salt poisoning or toxicosis when toxic levels of sodium and chloride accumulate in the blood after they ingest large amounts of salt or, in some species, are deprived of water. For birds, salt sources may include saline water and road salt.Normally, the salt glands of birds (Fig. 47.1) excrete sodium and chloride to maintain the proper physiologic chemical balance. However, when there has been insufficient time for acclimation of the salt gland to the saline environment, or when salt gland function is compromised by exposure to certain pesticides or oil, the electrolyte balance of the blood may be upset by the excess sodium and chloride, resulting in toxicosis. Salt accumulation on the outside of the body, or salt encrustation, is a greater problem for waterbirds that use very saline waters than is salt toxicosis. Salt encrustation can lead to exertion, acute muscle degeneration, and eventual drowning during the struggle to escape entrapment.

40 CFR 81.167 - Southeast Desert Intrastate Air Quality Control Region.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 18 2012-07-01 2012-07-01 false Southeast Desert Intrastate Air... Air Quality Control Regions § 81.167 Southeast Desert Intrastate Air Quality Control Region. The Southeast Desert Intrastate Air Quality Control Region (California) consists of the territorial area...

40 CFR 81.167 - Southeast Desert Intrastate Air Quality Control Region.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 18 2013-07-01 2013-07-01 false Southeast Desert Intrastate Air... Air Quality Control Regions § 81.167 Southeast Desert Intrastate Air Quality Control Region. The Southeast Desert Intrastate Air Quality Control Region (California) consists of the territorial area...

40 CFR 81.167 - Southeast Desert Intrastate Air Quality Control Region.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 18 2014-07-01 2014-07-01 false Southeast Desert Intrastate Air... Air Quality Control Regions § 81.167 Southeast Desert Intrastate Air Quality Control Region. The Southeast Desert Intrastate Air Quality Control Region (California) consists of the territorial area...

Herbicide hardwood crop tree release in central West Virginia

Treesearch

Jeffrey D. Kochenderfer; Shepard M. Zedaker; James E. Johnson; David W. Smith; Gary W. Miller

2001-01-01

Chemical crop tree release treatments were applied to young hardwood stands at three sites in central West Virginia to evaluate the effectiveness of glyphosate as Accord (41.5% SL), imazapyr as Arsenal AC (53.1% SL) and Chopper (27.6% EC), and triclopyr as Garlon 3A (44.4% triethylamine salt SL), and Garlon 4 (61.6% butoxyethyl ester EC) using hack-and-squirt injection...

Southwestern desert resources

USGS Publications Warehouse

Halvorson, William L.; van Riper, Charles; Schwalbe, Cecil R.

2010-01-01

The southwestern deserts stretch from southeastern California to west Texas and then south to central Mexico. The landscape of this region is known as basin and range topography featuring to "sky islands" of forest rising from the desert lowlands which creates a uniquely diverse ecology. The region is further complicated by an international border, where governments have caused difficulties for many animal populations. This book puts a spotlight on individual research projects which are specific examples of work being done in the area and when they are all brought together, to shed a general light of understanding the biological and cultural resources of this vast region so that those same resources can be managed as effectively and efficiently as possible. The intent is to show that collaborative efforts among federal, state agency, university, and private sector researchers working with land managers, provides better science and better management than when scientists and land managers work independently.

Desert Research and Technology Studies 2008 Report

NASA Technical Reports Server (NTRS)

Romig, Barbara; Kosmo, Joseph; Gernhardt, Michael; Abercromby, Andrew

2009-01-01

During the last two weeks of October 2008, the National Aeronautics and Space Administration (NASA) Johnson Space Center (JSC) Advanced Extravehicular Activity (AEVA) team led the field test portion of the 2008 Desert Research and Technology Studies (D-RATS) near Flagstaff, AZ. The Desert RATS field test activity is the year-long culmination of various individual science and advanced engineering discipline areas technology and operations development efforts into a coordinated field test demonstration under representative (analog) planetary surface terrain conditions. The 2008 Desert RATS was the eleventh RATS field test and was the most focused and successful test to date with participants from six NASA field centers, three research organizations, one university, and one other government agency. The main test objective was to collect Unpressurized Rover (UPR) and Lunar Electric Rover (LER) engineering performance and human factors metrics while under extended periods of representative mission-based scenario test operations involving long drive distances, night-time driving, Extravehicular Activity (EVA) operations, and overnight campover periods. The test was extremely successful with all teams meeting the primary test objective. This paper summarizes Desert RATS 2008 test hardware, detailed test objectives, test operations, and test results.

Limited production of sulfate and nitrate on front-associated dust storm particles moving from desert to distant populated areas in northwestern China

NASA Astrophysics Data System (ADS)

Wu, Feng; Zhang, Daizhou; Cao, Junji; Guo, Xiao; Xia, Yao; Zhang, Ting; Lu, Hui; Cheng, Yan

2017-12-01

Sulfate and nitrate compounds can greatly increase the hygroscopicity of mineral particles in the atmosphere and consequently alter the particles' physical and chemical properties. Their uptake on long-distance-transported Asian dust particles within mainland China has been reported to be substantial in previous studies, but the production was very inefficient in other studies. We compared these two salts in particles collected from a synoptic-scale, mid-latitude, cyclone-induced dust storm plume at the Tengger Desert (38.79° N, 105.38° E) and in particles collected in a postfrontal dust plume at an urban site in Xi'an (34.22° N, 108.87° E) when a front-associated dust storm from the Tengger Desert arrived there approximately 700 km downwind. The results showed that the sulfate concentration was not considerably different at the two sites, while the nitrate concentration was slightly larger at the urban site than that at the desert site. The estimated nitrate production rate was 4-5 ng µg-1 of mineral dust per day, which was much less than that in polluted urban air. The adiabatic process of the dust-loading air was suggested to be the reason for the absence of sulfate formation, and the uptake of background HNO3 was suggested to be the reason for the small nitrate production. According to our investigation of the published literature, the significant sulfate and nitrate in dust-storm-associated samples within the continental atmosphere reported in previous studies cannot be confirmed as actually produced on desert dust particles; the contribution from locally emitted and urban mineral particles or from soil-derived sulfate was likely substantial because the weather conditions in those studies indicated that the collection of the samples was started before dust arrival, or the air from which the samples were collected was a mixture of desert dust and locally emitted mineral particles. These results suggest that the production of nitrate and sulfate on dust

Simulation of Tsunami Resistance of a Pinus Thunbergii tree in Coastal Forest in Japan

NASA Astrophysics Data System (ADS)

Nanko, K.; Suzuki, S.; Noguchi, H.; Hagino, H.

2015-12-01

Forests reduce fluid force of tsunami, whereas extreme tsunami sometimes breaks down the forest trees. It is difficult to estimate the interactive relationship between the fluid and the trees because fluid deform tree architecture and deformed tree changes flow field. Dynamic tree deformation and fluid behavior should be clarified by fluid-structure interaction analysis. For the initial step, we have developed dynamic simulation of tree sway and breakage caused by tsunami based on a vibrating system with multiple degrees of freedom. The target specie of the simulation was Japanese black pine (pinus thunbergii), which is major specie in the coastal forest to secure livelihood area from the damage by blown sand and salt in Japanese coastal area. For the simulation, a tree was segmented into 0.2 m long circular truncated cones. Turning moment induced by tsunami and self-weight was calculated at each segment bottom. Tree deformation was computed on multi-degree-of-freedom vibration equation. Tree sway was simulated by iterative calculation of the tree deformation with time step 0.05 second with temporally varied flow velocity of tsunami. From the calculation of bending stress and turning moment at tree base, we estimated resistance of a Pinus thunbergii tree from tsunami against tree breakage.

McGET: A rapid image-based method to determine the morphological characteristics of gravels on the Gobi desert surface

NASA Astrophysics Data System (ADS)

Mu, Yue; Wang, Feng; Zheng, Bangyou; Guo, Wei; Feng, Yiming

2018-03-01

The relationship between morphological characteristics (e.g. gravel size, coverage, angularity and orientation) and local geomorphic features (e.g. slope gradient and aspect) of desert has been used to explore the evolution process of Gobi desert. Conventional quantification methods are time-consuming, inefficient and even prove impossible to determine the characteristics of large numbers of gravels. We propose a rapid image-based method to obtain the morphological characteristics of gravels on the Gobi desert surface, which is called the "morphological characteristics gained effectively technique" (McGET). The image of the Gobi desert surface was classified into gravel clusters and background by a machine-learning "classification and regression tree" (CART) algorithm. Then gravel clusters were segmented into individual gravel clasts by separating objects in images using a "watershed segmentation" algorithm. Thirdly, gravel coverage, diameter, aspect ratio and orientation were calculated based on the basic principles of 2D computer graphics. We validated this method with two independent datasets in which the gravel morphological characteristics were obtained from 2728 gravels measured in the field and 7422 gravels measured by manual digitization. Finally, we applied McGET to derive the spatial variation of gravel morphology on the Gobi desert along an alluvial-proluvial fan located in Hami, Xinjiang, China. The validated results show that the mean gravel diameter measured in the field agreed well with that calculated by McGET for large gravels (R2 = 0.89, P < 0.001). Compared to manual digitization, the McGET accuracies for gravel coverage, gravel diameter and aspect ratio were 97%, 83% and 96%, respectively. The orientation distributions calculated were consistent across two different methods. More importantly, McGET significantly shortens the time cost in obtaining gravel morphological characteristics in the field and laboratory. The spatial variation results

NASA Desert RATS 2011 Education Pilot Project and Classroom Activities

NASA Technical Reports Server (NTRS)

Gruener, J. E.; McGlone, M.; Allen, J.; Tobola, K.; Graff, P.

2012-01-01

The National Aeronautics and Space Administration's (NASA's) Desert Research and Technology Studies (Desert RATS) is a multi-year series of tests of hardware and operations carried out annually in the high desert of Arizona, as an analog to future exploration activities beyond low Earth orbit [1]. For the past several years, these tests have occurred in the San Francisco Volcanic Field, north of Flagstaff. For the 2011 Desert RATS season, the Exploration Systems Mission Directorate (ESMD) at NASA headquarters provided support to develop an education pilot project that would include student activities to parallel the Desert RATS mission planning and exploration activities in the classroom, and educator training sessions. The development of the pilot project was a joint effort between the NASA Johnson Space Center (JSC) Astromaterials Research and Exploration Science (ARES) Directorate and the Aerospace Education Services Project (AESP), managed at Penn State University.

Cryptogamic communities in biological soil crusts in arid deserts of China: Diversity and their relationships to habitats in different scales

NASA Astrophysics Data System (ADS)

Li, X. R.; He, M. Z.; Li, X. J.; Jia, R. L.

2012-04-01

Biological soil crusts (BSCs) are widespread communities of various diminutive organisms, including cryptogams such as cyanobacteria, algae, lichens and mosses, and other invisible organisms that are closely integrated with particles of topsoil. Few studies have considered their diversity and distribution pattern as related to environmental and climatic factors at different scales - in particular, little is known concerning the factors inducing the differences in crustal floral diversity for arid deserts in China. We investigated the distribution and characteristics of crustal communities with a total of 350 soil samplings in the main desert regions of northern China: the Horqin Sandland, Mu Us Sandland-Ordos Plateau, Tengger-Alxa Plateau, Qaidam Desert and Guerbantunggut Desert, which present a precipitation gradient, reducing from 450 mm in eastern to 80-100 mm in western deserts. The maximum cryptogamic species richness in crustal communities was 66, 42, 56, 22 and 54, respectively, in the above deserts. In general, species richness and biomass of crustal mosses were positive related with precipitation, while that of cyanobacteria and algae, as well as lichens were negative at a landscape scale. The results indicated topsoil physiochemical properties largely influenced the distribution pattern of crustal communities at the regional scale. Fine-textured and gypsum soils and soils with higher pH were favorable for various lichens, which were restricted by soils with higher total salt content. Moss species and biomass were closely related with soil water content rather than other properties, whereas there was higher diversity in cyanobacteria and algae at the site with relatively dry topsoil. In addition, the cover and biomass of mosses was positive correlated with the cover of C3 plants such as xerophytic shrubs due to providing shade. However, cover and biomass of lichens, cyanobacteria and algae were closely correlated with C4 plants, especially annuals

Atmospheric transport of mold spores in clouds of desert dust

USGS Publications Warehouse

Shinn, E.A.; Griffin, Dale W.; Seba, D.B.

2003-01-01

Fungal spores can be transported globally in clouds of desert dust. Many species of fungi (commonly known as molds) and bacteria--including some that are human pathogens--have characteristics suited to long-range atmospheric transport. Dust from the African desert can affect air quality in Africa, Europe, the Middle East, and the Americas. Asian desert dust can affect air quality in Asia, the Arctic, North America, and Europe. Atmospheric exposure to mold-carrying desert dust may affect human health directly through allergic induction of respiratory stress. In addition, mold spores within these dust clouds may seed downwind ecosystems in both outdoor and indoor environments.

America's Atomic Army: The Historical Archaeology of Camp Desert Rock

DOE Office of Scientific and Technical Information (OSTI.GOV)

Susan R. Edwards

2007-11-02

Established in 1951, Camp Desert Rock served as the training ground for America's 'Atomic Army'. For the next six years, U.S. ground troops traveled to the Nevada desert to participate in military maneuvers during atmospheric atomic weapons testing. Nearly 60,000 soldiers received physical and psychological training in atomic warfare. Abandoned when atmospheric testing ended, Camp Desert Rock was dismantled and its buildings moved to other locations. Today, the camp appears as a sterile expanse of desert marked by rock-lined tent platforms, concrete foundations, and trash scatters. Although visually unimposing, the site is rich with the history of America's nuclear testingmore » program.« less

Sonoran Desert: Fragile Land of Extremes

USGS Publications Warehouse

Produced and Directed by Wessells, Stephen

2003-01-01

'Sonoran Desert: Fragile Land of Extremes' shows how biologists with the U.S. Geological Survey work with other scientists in an effort to better understand native plants and animals such as desert tortoises, saguaro cacti, and Gila monsters. Much of the program was shot in and around Saguaro National Park near Tucson, Arizona. Genetic detective work, using DNA, focuses on understanding the lives of tortoises. Studies of saguaros over many decades clarify how these amazing plants reproduce and thrive in the desert. Threats from fire, diseases in tortoises, and a growing human population motivate the scientists. Their work to identify how these organisms live and survive is a crucial step for the sound management of biological resources on public lands. This 28-minute program, USGS Open-File Report 03-305, was shot entirely in high definition video and produced by the USGS Western Ecological Research Center and Southwest Biological Science Center; produced and directed by Stephen Wessells, Western Region Office of Communications.

Prolactin stress response does not predict brood desertion in a polyandrous shorebird.

PubMed

Kosztolányi, András; Küpper, Clemens; Chastel, Olivier; Parenteau, Charline; Yılmaz, K Tuluhan; Miklósi, Adám; Székely, Tamás; Lendvai, Adám Z

2012-05-01

One of the fundamental principles of the life-history theory is that parents need to balance their resources between current and future offspring. Deserting the dependent young is a radical life-history decision that saves resources for future reproduction but that may cause the current brood to fail. Despite the importance of desertion for reproductive success, and thus fitness, the neuroendocrine mechanisms of brood desertion are largely unknown. We investigated two candidate hormones that may influence brood desertion in the Kentish plover Charadrius alexandrinus: prolactin ('parental hormone') and corticosterone ('stress hormone'). Kentish plovers exhibit an unusually diverse mating and parental care system: brood desertion occurs naturally since either parent (the male or the female) may desert the brood after the chicks hatch and mate with a new partner shortly after. We measured the hormone levels of parents at hatching using the standard capture and restraint protocol. We subsequently followed the broods to determine whether a parent deserted the chicks. We found no evidence that either baseline or stress-induced prolactin levels of male or female parents predicted brood desertion. Although stress-induced corticosterone levels were generally higher in females compared with males, individual corticosterone levels did not explain the probability of brood desertion. We suggest that, in this species, low prolactin levels do not trigger brood desertion. In general, we propose that the prolactin stress response does not reflect overall parental investment in a species where different parts of the breeding cycle are characterized by contrasting individual investment strategies. Copyright © 2012 Elsevier Inc. All rights reserved.

78 FR 47409 - Meeting of the California Desert District Advisory Council

Federal Register 2010, 2011, 2012, 2013, 2014

2013-08-05

... California Desert District Advisory Council SUMMARY: Notice is hereby given, in accordance with Public Laws 92-463 and 94-579, that the California Desert District Advisory Council (DAC) to the Bureau of Land... Desert District Advisory Council, c/o Bureau of Land Management, External Affairs, 22835 Calle San Juan...

Moderately haloalkaliphilic actinomycetes in salt-affected soils

NASA Astrophysics Data System (ADS)

Zvyagintsev, D. G.; Zenova, G. M.; Oborotov, G. V.

2009-12-01

It was found that the population density of actinomycetes in solonchaks and saline desert soils varied from hundreds to tens of thousands of colony-forming units (CFUs) per 1 g of soil depending on soil type and was by 1-3 orders of magnitude lower than the number of mycelial bacteria in main soil types. Actinomycetes grow actively in saline soils, and the length of their mycelium reaches 140 m per 1 g of soil. Domination of moderately halophilic, alkaliphilic, and haloalkaliphilic actinomycetes, which grow well under 5% NaCl and pH 8-9, is a specific feature of actinomycetal complexes in saline soils. Representatives of Streptomyces and Micromonospora genera were found among the haloalkaliphilic actinomycetes. Micromonospores demonstrated lower (than streptomycetes) adaptability to high salt concentrations. Investigation of the phylogenetic position of isolated dominant haloalkaliphilic strains of streptomycetes performed on the basis of sequencing of the gene 16S rRNA enabled identifying these strains as Streptomyces pluricolorescens and S. prunicolor.

Food Deserts and Overweight Schoolchildren: Evidence from Pennsylvania

ERIC Educational Resources Information Center

Schafft, Kai A.; Jensen, Eric B.; Hinrichs, C. Clare

2009-01-01

The concept of the "food desert", an area with limited access to retail food stores, has increasingly been used within social scientific and public health research to explore the dimensions of spatial inequality and community well-being. While research has demonstrated that food deserts are frequently characterized by higher levels of…

Fog Bank, Namib Desert, Namibia, Africa

NASA Technical Reports Server (NTRS)

1991-01-01

Fog is the only source of moisture for desert dwelling animals and plants living in the Namib Desert sand dune field, Namibia (23.5N, 15.0E). Coastal stratus clouds provide most of the life supporting moisture as fog droplets in this arid land where the usual annual rainfall is less than a quarter of an inch for decades at a time. In this view, the stratus clouds over the coast conform to the dune pattern proving that the fog is in ground contact.

Fog Bank, Namib Desert, Namibia, Africa

NASA Image and Video Library

1991-12-01

Fog is the only source of moisture for desert dwelling animals and plants living in the Namib Desert sand dune field, Namibia (23.5N, 15.0E). Coastal stratus clouds provide most of the life supporting moisture as fog droplets in this arid land where the usual annual rainfall is less than a quarter of an inch for decades at a time. In this view, the stratus clouds over the coast conform to the dune pattern proving that the fog is in ground contact.

An Integrated Multi-Sensor Approach to Monitor Desert Environments by UAV and Satellite Sensors: Case Study Kubuqi Desert, China

NASA Astrophysics Data System (ADS)

Kim, J.; Lin, C. W.; vanGasselt, S.; Lin, S.; Lan, C. W.

2017-12-01

Expanding deserts have been causing significant socio-economical threats by, e.g., hampering anthropogenic activities or causing decline of agricultural productivity. Countries in the Asian-Pacific regions in particular have been suffering from dust storms originating in the arid deserts of China, Mongolia and central Asia. In order to mitigate such environmental interferences by means of, e.g. combat desertification activities and early warning systems, the establishment of reliable desert monitoring schemes is needed. In this study, we report on a remote sensing data fusion approach to constantly and precisely monitor desert environments. We have applied this approach over a test site located in the Kubuqi desert located in Northeast China and which is considered to be a major contributor of dust storms today. In order to understand spatial and temporal trends of desertification, the planimetric distribution and 3D shape and size of sand dunes were reconstructed using Digital Terrain Models (DTM) derived from stereo observations made by Unmanned Aerial Vehicles (UAV). Based on this, the volumetric change of sand dunes was directly estimated through co-registered DTMs. We furthermore derived and investigated topographic parameters, such as the aerodynamic roughness length, the protrusion coefficient, the Normalized Difference Angular Index, and the phase coherence derived from spaceborne optical/synthetic aperture radar (SAR) remote sensing assets with the calibration index from UAV observation. Throughout such a multi-data approach, temporal changes of a target's environmental parameters can be traced, analyzed and correlated with weather conditions. An improved understanding of aeolian processes in sand deserts will be a valuable contribution for desertification combat activities and early warning systems for dust storm generation. Future research needs to be conducted over more extensive spatial and temporal domains, also by combining investigations on the

Reference intervals and physiologic alterations in hematologic and biochemical values of free-ranging desert tortoises in the Mojave Desert

USGS Publications Warehouse

Christopher, Mary M.; Berry, Kristin H.; Wallis, I.R.; Nagy, K.A.; Henen, B.T.; Peterson, C.C.

1999-01-01

Desert tortoise (Gopherus agassizii) populations have experienced precipitous declines resulting from the cumulative impact of habitat loss, and human and disease-related mortality. Evaluation of hematologic and biochemical responses of desert tortoises to physiologic and environmental factors can facilitate the assessment of stress and disease in tortoises and contribute to management decisions and population recovery. The goal of this study was to obtain and analyze clinical laboratory data from free-ranging desert tortoises at three sites in the Mojave Desert (California, USA) between October 1990 and October 1995, to establish reference intervals, and to develop guidelines for the interpretation of laboratory data under a variety of environmental and physiologic conditions. Body weight, carapace length, and venous blood samples for a complete blood count and clinical chemistry profile were obtained from 98 clinically healthy adult desert tortoises of both sexes at the Desert Tortoise Research Natural area (western Mojave), Goffs (eastern Mojave) and Ivanpah Valley (northeastern Mojave). Samples were obtained four times per year, in winter (February/March), spring (May/June), summer (July/August), and fall (October). Years of near-, above- and below-average rainfall were represented in the 5 yr period. Minimum, maximum and median values, and central 95 percentiles were used as reference intervals and measures of central tendency for tortoises at each site and/or season. Data were analyzed using repeated measures analysis of variance for significant (P < 0.01) variation on the basis of sex, site, season, and interactions between these variables. Significant sex differences were observed for packed cell volume, hemoglobin concentration, aspartate transaminase activity, and cholesterol, triglyceride, calcium, and phosphorus concentrations. Marked seasonal variation was observed in most parameters in conjunction with reproductive cycle, hibernation, or seasonal

High-frequency rock temperature data from hyper-arid desert environments in the Atacama and the Antarctic Dry Valleys and implications for rock weathering

NASA Astrophysics Data System (ADS)

McKay, Christopher P.; Molaro, Jamie L.; Marinova, Margarita M.

2009-09-01

In desert environments with low water and salt contents, rapid thermal variations may be an important source of rock weathering. We have obtained temperature measurements of the surface of rocks in hyper-arid hot and cold desert environments at a rate of 1/s over several days. The values of temperature change over 1-second intervals were similar in hot and cold deserts despite a 30 °C difference in absolute rock surface temperature. The average percentage of the time dT/dt > 2 °C/min was ~ 8 ± 3%, > 4 °C/min was 1 ± 0.9%, and > 8 °C/min was 0.02 ± 0.03%. The maximum change over a 1-second interval was ~ 10 °C/min. When sampled to simulate data taken over intervals longer than 1 s, we found a reduction in time spent above the 2 °C/min temperature gradient threshold. For 1-minute samples, the time spent above any given threshold was about two orders of magnitude lower than the corresponding value for 1-second sampling. We suggest that a rough measure of efficacy of weathering as a function of frequency is the product of the percentage of time spent above a given threshold value multiplied by the damping depth for the corresponding frequency. This product has a broad maximum for periods between 3 and 10 s.

HK2 Proximal Tubule Epithelial Cells Synthesize and Secrete Plasma Proteins Predominantly Through the Apical Surface.

PubMed

Zhao, Ke-Wei; Murray, Elsa J Brochmann; Murray, Samuel S

2017-04-01

Renal proximal tubule epithelial cells (PTECs) are known to reabsorb salts and small plasma proteins filtered through Bowman's capsule. Following acute kidney injury, PTECs assume some characteristics of hepatocytes in producing various plasma proteins. We now demonstrate that even at a resting state, a PTEC cell line, HK2 expresses mRNAs for and synthesizes and secretes plasma proteins in a complex with complement C3, an α 2 -macroglobulin family chaperone, including albumin, transferrin, α 1 -antitrypsin, α 1 -antichymotrypsin, α 2 -HS-glycoprotein, ceruloplasmin, haptoglobin, C1-inhibitor, secreted phosphoprotein-24, and insulin-like growth factor-1. When grown on transwell inserts, HK2 cells predominantly secrete (∼90%) plasma proteins into the apical side and a smaller fraction into the basolateral side as determined by ELISA assays. When cultured in the presence of exogenous cytokines such as IL1β, IL6, TNFα, BMP2, or TGFβ1, HK2 cell mRNA expressions for plasma proteins were variably affected whereas basolateral secretions were elevated to or in excess of those of the apical level. In addition, HK2 cells produce proTGFβ1 with its intact N-terminal latency associated peptide and latent-TGF-β-binding proteins. The complex cannot be dissociated under conditions of SDS, heating, and electrophoresis. Moreover, HK2 cells maintain their ability to quickly uptake exogenously added serum proteins from the culture medium, as if they are recognized differently by the endocytic receptors. These results provide new insight into the hepatization of PTECs. In addition to their unique uptake of plasma proteins and salts from the filtrate, they are a source of urinary proteins under normal conditions as wells as in chronic and acute kidney diseases. J. Cell. Biochem. 118: 924-933, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Effects of altered temperature and precipitation on desert protozoa associated with biological soil crusts

USGS Publications Warehouse

Darby, B.J.; Housman, D.C.; Zaki, A.M.; Shamout, Y.; Adl, S.M.; Belnap, J.; Neher, D.A.

2006-01-01

Biological soil crusts are diverse assemblages of bacteria, cyanobacteria, algae, fungi, lichens, and mosses that cover much of arid land soils. The objective of this study was to quantify protozoa associated with biological soil crusts and test the response of protozoa to increased temperature and precipitation as is predicted by some global climate models. Protozoa were more abundant when associated with cyanobacteria/lichen crusts than with cyanobacteria crusts alone. Amoebae, flagellates, and ciliates originating from the Colorado Plateau desert (cool desert, primarily winter precipitation) declined 50-, 10-, and 100-fold, respectively, when moved in field mesocosms to the Chihuahuan Desert (hot desert, primarily summer rain). However, this was not observed in protozoa collected from the Chihuahuan Desert and moved to the Sonoran desert (hot desert, also summer rain, but warmer than Chihuahuan Desert). Protozoa in culture began to encyst at 37??C. Cysts survived the upper end of daily temperatures (37-55??C), and could be stimulated to excyst if temperatures were reduced to 15??C or lower. Results from this study suggest that cool desert protozoa are influenced negatively by increased summer precipitation during excessive summer temperatures, and that desert protozoa may be adapted to a specific desert's temperature and precipitation regime. ?? 2006 by the International Society of Protistologists.

Water use sources of desert riparian Populus euphratica forests.

PubMed

Si, Jianhua; Feng, Qi; Cao, Shengkui; Yu, Tengfei; Zhao, Chunyan

2014-09-01

Desert riparian forests are the main body of natural oases in the lower reaches of inland rivers; its growth and distribution are closely related to water use sources. However, how does the desert riparian forest obtains a stable water source and which water sources it uses to effectively avoid or overcome water stress to survive? This paper describes an analysis of the water sources, using the stable oxygen isotope technique and the linear mixed model of the isotopic values and of desert riparian Populus euphratica forests growing at sites with different groundwater depths and conditions. The results showed that the main water source of Populus euphratica changes from water in a single soil layer or groundwater to deep subsoil water and groundwater as the depth of groundwater increases. This appears to be an adaptive selection to arid and water-deficient conditions and is a primary reason for the long-term survival of P. euphratica in the desert riparian forest of an extremely arid region. Water contributions from the various soil layers and from groundwater differed and the desert riparian P. euphratica forests in different habitats had dissimilar water use strategies.

Community adaptations to an impending food desert in rural Appalachia, USA.

PubMed

Miller, Wayne C; Rogalla, Denver; Spencer, Dustin; Zia, Nida; Griffith, Brian N; Heinsberg, Haylee B

2016-01-01

The United States Department of Agriculture (USDA) describes a food desert as an urban neighborhood or rural town without ready access to fresh, healthy, and affordable food. An estimated 2.3 million rural Americans live in food deserts. One goal of the USDA is to eliminate food deserts. However, at a time when some food deserts are being eliminated, hundreds of grocery stores are closing, causing other food deserts to arise. The literature is scarce on how a community adapts to an impending food desert. Alderson, West Virginia, USA (population 1184) rallied to face an impending food desert when the only grocery store in town closed in December 2014. This study investigated how this small rural community adapted to its oncoming food desert. A community member survey was administered to 155 Alderson families (49%) to determine how the new food desert affected family food acquisition and storage behaviors. A restaurant survey was given to the town's four restaurants to determine how the food desert affected their businesses. Sales data for a new food hub (Green Grocer) was obtained to see if this new initiative offset the negative effects of the food desert. ANOVA and t-tests were used to compare group numerical data. Two group response rates were compared by testing the equality of two proportions. Categorical data were analyzed with the χ2 or frequency distribution analysis. Group averages are reported as mean ± standard error of the mean. Significance for all analyses was set at p<0.05. Even though 86% of the population shopped at the new Green Grocer, 77% did most of their shopping at a store at least 17.7 km (11 miles) from home. The number of long-distance monthly shopping trips made after the food desert (3.3±0.4) did not change significantly (p=0.16) from the number before the food desert (2.8±0.3). Price comparisons among the Green Grocer and three distant supermarkets showed a 30% savings by traveling to distant supermarkets

Role of remote sensing in desert locust early warning

NASA Astrophysics Data System (ADS)

Cressman, Keith

2013-01-01

Desert locust (Schistocerca gregaria, Forskål) plagues have historically had devastating consequences on food security in Africa and Asia. The current strategy to reduce the frequency of plagues and manage desert locust infestations is early warning and preventive control. To achieve this, the Food and Agriculture Organization of the United Nations operates one of the oldest, largest, and best-known migratory pest monitoring systems in the world. Within this system, remote sensing plays an important role in detecting rainfall and green vegetation. Despite recent technological advances in data management and analysis, communications, and remote sensing, monitoring desert locusts and preventing plagues in the years ahead will continue to be a challenge from a geopolitical and financial standpoint for affected countries and the international donor community. We present an overview of the use of remote sensing in desert locust early warning.

Reset Tree-Based Optical Fault Detection

PubMed Central

Lee, Dong-Geon; Choi, Dooho; Seo, Jungtaek; Kim, Howon

2013-01-01

In this paper, we present a new reset tree-based scheme to protect cryptographic hardware against optical fault injection attacks. As one of the most powerful invasive attacks on cryptographic hardware, optical fault attacks cause semiconductors to misbehave by injecting high-energy light into a decapped integrated circuit. The contaminated result from the affected chip is then used to reveal secret information, such as a key, from the cryptographic hardware. Since the advent of such attacks, various countermeasures have been proposed. Although most of these countermeasures are strong, there is still the possibility of attack. In this paper, we present a novel optical fault detection scheme that utilizes the buffers on a circuit's reset signal tree as a fault detection sensor. To evaluate our proposal, we model radiation-induced currents into circuit components and perform a SPICE simulation. The proposed scheme is expected to be used as a supplemental security tool. PMID:23698267

Role of pioneer species in revegetation of disturbed desert areas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wallace, A.; Romney, E.M.

1980-01-01

The northern Mojave Desert, as are many deserts, is characterized in part by small fertile islands in which exist individual shrub clumps each containing two or more plants. These fertile sites promote characteristic organization of both plant and animal activity in the desert. Destruction of these fertile sites make revegetation extremely difficult because most seedlings germinate in these sites. Some pioneer species do, however, germinate and survive in the bare areas between the fertile sites. Four such species in the northern Mojave Desert are Acamptopappus shockleyi Gray, Lepidium fremontii Wats., Sphaeralcea ambigua Gray, and Atriplex confertifolia (Torr. and Frem.) Wats.more » These four-species may have a role in starting new fertile islands.« less

Biotic interactions mediate the expansion of black mangrove (Avicennia germinans) into salt marshes under climate change.

PubMed

Guo, Hongyu; Zhang, Yihui; Lan, Zhenjiang; Pennings, Steven C

2013-09-01

Many species are expanding their distributions to higher latitudes due to global warming. Understanding the mechanisms underlying these distribution shifts is critical for better understanding the impacts of climate changes. The climate envelope approach is widely used to model and predict species distribution shifts with changing climates. Biotic interactions between species, however, may also influence species distributions, and a better understanding of biotic interactions could improve predictions based solely on climate envelope models. Along the northern Gulf of Mexico coast, USA, subtropical black mangrove (Avicennia germinans) at the northern limit of its distribution grows sympatrically with temperate salt marsh plants in Florida, Louisiana, and Texas. In recent decades, freeze-free winters have led to an expansion of black mangrove into salt marshes. We examined how biotic interactions between black mangrove and salt marsh vegetation along the Texas coast varied across (i) a latitudinal gradient (associated with a winter-temperature gradient); (ii) the elevational gradient within each marsh (which creates different marsh habitats); and (iii) different life history stages of black mangroves (seedlings vs. juvenile trees). Each of these variables affected the strength or nature of biotic interactions between black mangrove and salt marsh vegetation: (i) Salt marsh vegetation facilitated black mangrove seedlings at their high-latitude distribution limit, but inhibited black mangrove seedlings at lower latitudes; (ii) mangroves performed well at intermediate elevations, but grew and survived poorly in high- and low-marsh habitats; and (iii) the effect of salt marsh vegetation on black mangroves switched from negative to neutral as black mangroves grew from seedlings into juvenile trees. These results indicate that the expansion of black mangroves is mediated by complex biotic interactions. A better understanding of the impacts of climate change on ecological

Drought stress, growth, and nonstructural carbohydrate dynamics of pine trees in a semi-arid forest

NASA Astrophysics Data System (ADS)

Klein, Tamir; Yakir, Dan; Hoch, Günter

2014-05-01

• In trees under prolonged drought, both carbon uptake (C source) and growth (C sink) typically decrease. This correlation raises two important questions: (1) to what degree is tree growth limited by C availability; and (2) Is growth limited by concurrent C storage (e.g. as nonstructural carbohydrates, NSC). • To test the relationships between drought, growth, and C reserves, we monitored the changes in NSC levels and constructed stem growth chronologies of Pinus halepensis trees of three drought stress levels growing in Yatir forest, Israel, at the dry limit of forest existence. • Moderately stressed and stressed trees showed 37% and 21% of the stem growth of healthy trees in 2012; 71% and 31% of the sap flux density; and 79% and 66% of the final needle length. In spite of these large reductions, both starch and soluble sugars concentrations in branches of these trees were similar in all trees throughout the dry season (2-4% dry mass). At the same time the root starch concentrations of moderately stressed and stressed trees were 47% and 58% of that of healthy trees, but never below 2% d.m. • Our results suggest that the drought-induced growth reduction is associated with a general C shortage, rather than competition with concurrent C storage. The relatively small effect of drought stress level on NSC dynamics, the maintenance of a 2% d.m. starch, and the continued sap flow indicate that a whole-tree C starvation is not likely to occur in these trees growing at the edge of the desert. Special request: If the abstract is not accepted for presentation in this session, please consider for presentation in session BG2.11 Plant traits and biogeochemical cycles. Thank you.

Water balance in desert Drosophila: lessons from non-charismatic microfauna.

PubMed

Gibbs, Allen G

2002-11-01

Water stress is a particularly important problem for insects and other small organisms in arid environments. Cactophilic fruit flies in the genus Drosophila have invaded deserts on numerous occasions, including multiple independent invasions of North American deserts. Because the evolutionary history of this genus is so well studied, we can investigate the mechanisms of adaptation in a rigorous phylogenetic context. As expected, desert fruit flies lose water less rapidly than their mesic congeners. They are also able to tolerate the loss of a greater percentage of body water, but this difference is mainly due to phylogenetic history, and does not represent an adaptation specifically to desert habitats. A laboratory analogue of desert Drosophila is provided by populations of D. melanogaster that have been subjected to selection for desiccation resistance. Selected populations resemble desert species in that they lose water slowly, relative to control populations, and are not more tolerant of dehydration stress. They differ, however, in having much higher water contents and different behavioral responses to desiccating conditions. Our comparisons of laboratory and natural populations reveal that not all possible adaptive mechanisms evolve in stressful environments. Different physiological and behavioral strategies may evolve depending upon the particular options available in the environment.

Habitat selection by juvenile Mojave Desert tortoises

USGS Publications Warehouse

Todd, Brian D; Halstead, Brian J.; Chiquoine, Lindsay P.; Peaden, J. Mark; Buhlmann, Kurt A.; Tuberville, Tracey D.; Nafus, Melia G.

2016-01-01

Growing pressure to develop public lands for renewable energy production places several protected species at increased risk of habitat loss. One example is the Mojave desert tortoise (Gopherus agassizii), a species often at the center of conflicts over public land development. For this species and others on public lands, a better understanding of their habitat needs can help minimize negative impacts and facilitate protection or restoration of habitat. We used radio-telemetry to track 46 neonate and juvenile tortoises in the Eastern Mojave Desert, California, USA, to quantify habitat at tortoise locations and paired random points to assess habitat selection. Tortoise locations near burrows were more likely to be under canopy cover and had greater coverage of perennial plants (especially creosote [Larrea tridentata]), more coverage by washes, a greater number of small-mammal burrows, and fewer white bursage (Ambrosia dumosa) than random points. Active tortoise locations away from burrows were closer to washes and perennial plants than were random points. Our results can help planners locate juvenile tortoises and avoid impacts to habitat critical for this life stage. Additionally, our results provide targets for habitat protection and restoration and suggest that diverse and abundant small-mammal populations and the availability of creosote bush are vital for juvenile desert tortoises in the Eastern Mojave Desert.

Liquid Water Restricts Habitability in Extreme Deserts.

PubMed

Cockell, Charles S; Brown, Sarah; Landenmark, Hanna; Samuels, Toby; Siddall, Rebecca; Wadsworth, Jennifer

2017-04-01

Liquid water is a requirement for biochemistry, yet under some circumstances it is deleterious to life. Here, we show that liquid water reduces the upper temperature survival limit for two extremophilic photosynthetic microorganisms (Gloeocapsa and Chroococcidiopsis spp.) by greater than 40°C under hydrated conditions compared to desiccated conditions. Under hydrated conditions, thermal stress causes protein inactivation as shown by the fluorescein diacetate assay. The presence of water was also found to enhance the deleterious effects of freeze-thaw in Chroococcidiopsis sp. In the presence of water, short-wavelength UV radiation more effectively kills Gloeocapsa sp. colonies, which we hypothesize is caused by factors including the greater penetration of UV radiation into hydrated colonies compared to desiccated colonies. The data predict that deserts where maximum thermal stress or irradiation occurs in conjunction with the presence of liquid water may be less habitable to some organisms than more extreme arid deserts where organisms can dehydrate prior to being exposed to these extremes, thus minimizing thermal and radiation damage. Life in extreme deserts is poised between the deleterious effects of the presence and the lack of liquid water. Key Words: Deserts-Extremophiles-Stress-High temperatures-UV radiation-Desiccation. Astrobiology 17, 309-318.

Hydrologic influences on soil properties along ephemeral rivers in the Namib Desert

USGS Publications Warehouse

Jacobson, P.J.; Jacobson, K.M.; Angermeier, P.L.; Cherry, D.S.

2000-01-01

Soils were examined along three ephemeral rivers in the Namib Desert to assess the influence of their hydrologic characteristics on soil properties. Soils consisted of layers of fluvially deposited, organic-rich silts, interstratified with fluvial and aeolian sands. The most significant influence of the ephemeral hydrologic regime upon soils was related to the downstream alluviation associated with hydrologic decay. This alluviation increased the silt proportion of soils in the lower reaches of the rivers. Organic carbon, nitrogen and phosphorous were correlated with silt content, and silt deposition patterns influenced patterns of moisture availability and plant rooting, creating and maintaining micro-habitats for various organisms. Localized salinization occurred in association with wetland sites and soluble salt content tended to increase downstream. Because of the covariance between silt and macronutrients, and the influence of silt upon moisture availability and habitat suitability, alluviation patterns associated with the hydrologic regime strongly influence the structure, productivity, and spatial distribution of biotic communities in ephemeral river ecosystems. (C) 2000 Academic Press.

The provenance of Taklamakan desert sand

NASA Astrophysics Data System (ADS)

Rittner, Martin; Vermeesch, Pieter; Carter, Andrew; Bird, Anna; Stevens, Thomas; Garzanti, Eduardo; Andò, Sergio; Vezzoli, Giovanni; Dutt, Ripul; Xu, Zhiwei; Lu, Huayu

2016-03-01

Sand migration in the vast Taklamakan desert within the Tarim Basin (Xinjiang Uyghur Autonomous region, PR China) is governed by two competing transport agents: wind and water, which work in diametrically opposed directions. Net aeolian transport is from northeast to south, while fluvial transport occurs from the south to the north and then west to east at the northern rim, due to a gradual northward slope of the underlying topography. We here present the first comprehensive provenance study of Taklamakan desert sand with the aim to characterise the interplay of these two transport mechanisms and their roles in the formation of the sand sea, and to consider the potential of the Tarim Basin as a contributing source to the Chinese Loess Plateau (CLP). Our dataset comprises 39 aeolian and fluvial samples, which were characterised by detrital-zircon U-Pb geochronology, heavy-mineral, and bulk-petrography analyses. Although the inter-sample differences of all three datasets are subtle, a multivariate statistical analysis using multidimensional scaling (MDS) clearly shows that Tarim desert sand is most similar in composition to rivers draining the Kunlun Shan (south) and the Pamirs (west), and is distinctly different from sediment sources in the Tian Shan (north). A small set of samples from the Junggar Basin (north of the Tian Shan) yields different detrital compositions and age spectra than anywhere in the Tarim Basin, indicating that aeolian sediment exchange between the two basins is minimal. Although river transport dominates delivery of sand into the Tarim Basin, wind remobilises and reworks the sediment in the central sand sea. Characteristic signatures of main rivers can be traced from entrance into the basin to the terminus of the Tarim River, and those crossing the desert from the south to north can seasonally bypass sediment through the sand sea. Smaller ephemeral rivers from the Kunlun Shan end in the desert and discharge their sediment there. Both river run

From Fireproof Desert to Flammable Grassland: Buffelgrass Invasion in the Sonoran Desert

NASA Astrophysics Data System (ADS)

Betancourt, J. L.

2007-12-01

Only a few decades ago, the Sonoran Desert of northwestern Mexico and southern Arizona was considered mostly fireproof, a case of not enough fine fuel to connect the dominant shrubs and cacti. This has changed with invasions by non-native, winter annual and summer-flower perennial grasses that are rapidly transforming fireproof desert into flammable grassland. Of particular concern is buffelgrass, Pennisetum ciliare, a fire-prone and invasive African perennial grass that has already converted millions of hectares across Sonora since the mid-1960s and has made quick headway in southern and central Arizona beginning in the 1980s. Near Tucson and Phoenix, AZ, buffelgrass invasion is proceeding exponentially, with population expansion (and the costs of mitigation) more than doubling every year. As this conversion progresses, there will be increased fire risks, lost tourist revenue, diminished property values, insurmountable setbacks to conservation efforts, and the threat of large ignition fronts in desert valleys routinely spreading into the mountains. Although somewhat belated, an integrated, multi-jurisdictional effort is being organized to reduce ecological and economic impacts. My presentation will summarize the history and context of buffelgrass introduction and invasion, the disconnect in attitudes and policies across state and international boundaries, ongoing management efforts, the role of science and responsibilities of scientists, accelerated spread with changing climate, and impacts to regional ecosystems and economies. This narrative may serve as a template for other semi-arid lands where buffelgrass and similar grasses have become invasive, including Australia, South America, and many islands in the Pacific Ocean (including Hawaii), Indian Ocean, and Caribbean Sea.

A survey of the microbial community in the rhizosphere of two dominant shrubs of the Negev Desert highlands, Zygophyllum dumosum (Zygophyllaceae) and Atriplex halimus (Amaranthaceae), using cultivation-dependent and cultivation-independent methods.

PubMed

Kaplan, Drora; Maymon, Maskit; Agapakis, Christina M; Lee, Andrew; Wang, Andrew; Prigge, Barry A; Volkogon, Mykola; Hirsch, Ann M

2013-09-01

Plant roots comprise more than 50% of the plant's biomass. Part of that biomass includes the root microbiome, the assemblage of bacteria and fungi living in the 1-3 mm region adjacent to the external surface of the root, the rhizosphere. We hypothesized that the microorganisms living in the rhizosphere and in bulk soils of the harsh environment of the Negev Desert of Israel had potential for use as plant-growth-promoting bacteria (PGPB) to improve plant productivity in nutrient-poor, arid soils that are likely to become more common as the climate changes. • We used cultivation-dependent methods including trap experiments with legumes to find nitrogen-fixing rhizobia, specialized culture media to determine iron chelation via siderophores and phosphate-solubilizing and cellulase activities; cultivation-independent methods, namely 16S rDNA cloning and sequencing; and also community-level physiological profiling to discover soil microbes associated with the Negev desert perennials Zygophyllum dumosum and Atriplex halimus during the years 2009-2010. • We identified a number of PGPB, both epiphytes and endophytes, which fix nitrogen, chelate iron, solubilize phosphate, and secrete cellulase, as well as many other bacteria and some fungi, thereby providing a profile of the microbiomes that support the growth of two desert perennials. • We generated a snapshot of the microbial communities in the Negev Desert, giving us an insight in its natural state. This desert, like many arid environments, is vulnerable to exploitation for other purposes, including solar energy production and dry land farming.

Detecting Leaf Pulvinar Movements on NDVI Time Series of Desert Trees: A New Approach for Water Stress Detection

PubMed Central

Chávez, Roberto O.; Clevers, Jan G. P. W.; Verbesselt, Jan; Naulin, Paulette I.; Herold, Martin

2014-01-01

Heliotropic leaf movement or leaf ‘solar tracking’ occurs for a wide variety of plants, including many desert species and some crops. This has an important effect on the canopy spectral reflectance as measured from satellites. For this reason, monitoring systems based on spectral vegetation indices, such as the normalized difference vegetation index (NDVI), should account for heliotropic movements when evaluating the health condition of such species. In the hyper-arid Atacama Desert, Northern Chile, we studied seasonal and diurnal variations of MODIS and Landsat NDVI time series of plantation stands of the endemic species Prosopis tamarugo Phil., subject to different levels of groundwater depletion. As solar irradiation increased during the day and also during the summer, the paraheliotropic leaves of Tamarugo moved to an erectophile position (parallel to the sun rays) making the NDVI signal to drop. This way, Tamarugo stands with no water stress showed a positive NDVI difference between morning and midday (ΔNDVImo-mi) and between winter and summer (ΔNDVIW-S). In this paper, we showed that the ΔNDVImo-mi of Tamarugo stands can be detected using MODIS Terra and Aqua images, and the ΔNDVIW-S using Landsat or MODIS Terra images. Because pulvinar movement is triggered by changes in cell turgor, the effects of water stress caused by groundwater depletion can be assessed and monitored using ΔNDVImo-mi and ΔNDVIW-S. For an 11-year time series without rainfall events, Landsat ΔNDVIW-S of Tamarugo stands showed a positive linear relationship with cumulative groundwater depletion. We conclude that both ΔNDVImo-mi and ΔNDVIW-S have potential to detect early water stress of paraheliotropic vegetation. PMID:25188305

Summer Monsoon, Kalahari Desert, Africa

NASA Image and Video Library

1992-11-01

STS052-152-047 (22 Oct- 1 Nov 1992) --- The Kalahari Desert had not seen any significant rainfall for months before the launch of STS-52. Here, Shuttle astronauts have captured the onset of the (Southern Hemisphere) summer monsoon over the Kalahari Desert, as illustrated by the large thunderstorm towers poking up through the sun's terminator. The summer monsoon, with its associated thunderstorms, generally lasts from November through March. Scientist observers of this area report that the summer monsoon contributes most of the annual rainfall to this environmentally sensitive area. Shuttle nadir position: 28.0 degrees south, 25.1 degrees east. The center of the scene is 22.0 degrees south, 25.0 degrees east, 16:20:04 GMT.

Evidence for photochemical production of reactive oxygen species in desert soils.

PubMed

Georgiou, Christos D; Sun, Henry J; McKay, Christopher P; Grintzalis, Konstantinos; Papapostolou, Ioannis; Zisimopoulos, Dimitrios; Panagiotidis, Konstantinos; Zhang, Gaosen; Koutsopoulou, Eleni; Christidis, George E; Margiolaki, Irene

2015-05-11

The combination of intense solar radiation and soil desiccation creates a short circuit in the biogeochemical carbon cycle, where soils release significant amounts of CO2 and reactive nitrogen oxides by abiotic oxidation. Here we show that desert soils accumulate metal superoxides and peroxides at higher levels than non-desert soils. We also show the photogeneration of equimolar superoxide and hydroxyl radical in desiccated and aqueous soils, respectively, by a photo-induced electron transfer mechanism supported by their mineralogical composition. Reactivity of desert soils is further supported by the generation of hydroxyl radical via aqueous extracts in the dark. Our findings extend to desert soils the photogeneration of reactive oxygen species by certain mineral oxides and also explain previous studies on desert soil organic oxidant chemistry and microbiology. Similar processes driven by ultraviolet radiation may be operating in the surface soils on Mars.

Mojave Desert Diary

ERIC Educational Resources Information Center

Breed, Allen F.

1974-01-01

This is an account of a trip to the Mojave Desert sponsored by the California Youth Authority's Community Parole Center for wards who are selected on the basis of their potential for growth and their ability to make a connection between what they do in the wilderness and what they do on the streets. (PD)

Desert Tortoise Head-start Program at Twentynine Palms Marine Base

DTIC Science & Technology

2013-04-02

Hillard. Shell hardness measurement in juvenile desert tortoises, Gopherus agassizii, Herpetological Review, (09 2011): 0. doi: 07/23/2012 2.00...yearlings released to the open desert. Herpetological Conservation and Biology.

Individual based, long term monitoring of acacia trees in hyper arid zone: Integration of a field survey and a remote sensing approach

NASA Astrophysics Data System (ADS)

Isaacson, Sivan; Blumberg, Dan G.; Ginat, Hanan; Shalmon, Benny

2013-04-01

Vegetation in hyper arid zones is very sparse as is. Monitoring vegetation changes in hyper arid zones is important because any reduction in the vegetation cover in these areas can lead to a considerable reduction in the carrying capacity of the ecological system. This study focuses on the impact of climate fluctuations on the acacia population in the southern Arava valley, Israel. The period of this survey includes a sequence of dry years with no flashfloods in most of the plots that ended in two years with vast floods. Arid zone acacia trees play a significant role in the desert ecosystem by moderating the extreme environmental conditions including radiation, temperature, humidity and precipitation. The trees also provide nutrients for the desert dwellers. Therefore, acacia trees in arid zones are considered to be `keystone species', because they have major influence over both plants and animal species, i.e., biodiversity. Long term monitoring of the acacia tree population in this area can provide insights into long term impacts of climate fluctuations on ecosystems in arid zones. Since 2000, a continuous yearly based survey on the three species of acacia population in seven different plots is conducted in the southern Arava (established by Shalmon, ecologist of the Israel nature and parks authority). The seven plots representing different ecosystems and hydrological regimes. A yearly based population monitoring enabled us to determine the mortality and recruitment rate of the acacia populations as well as growing rates of individual trees. This survey provides a unique database of the acacia population dynamics during a sequence of dry years that ended in a vast flood event during the winter of 2010. A lack of quantitative, nondestructive methods to estimate and monitor stress status of the acacia trees, led us to integrate remote sensing tools (ground and air-based) along with conventional field measurements in order to develop a long term monitoring of acacia

Interaction of ACE genotype and salt intake on hypertension among Chinese Kazakhs: results from a population-based cross-sectional study.

PubMed

Wang, Yuyan; Zhang, Biao; Hou, Lei; Han, Wei; Xue, Fang; Wang, Yanhong; Tang, Yong; Liang, Shaohua; Wang, Weizhi; Asaiti, Kuliqian; Wang, Zixing; Hu, Yaoda; Wang, Lei; Qiu, Changchun; Zhang, Mingtao; Jiang, Jingmei

2017-05-17

To explore the effect of interaction between ACE genotype and salt intake on hypertension among Chinese Kazakhs, and to compare applications of interactions between logistic model and generalised partially linear tree-based regression (GPLTR) model. Population-based cross-sectional study. Hong Dun, North Xinjiang, China. Non-consanguineous Chinese Kazakh participants (n=916, 342 men and 574 women) aged ≥30 years. Association between ACE genotype and hypertension, association between salt intake and hypertension, and interaction of ACE genotype and salt intake on hypertension in two models. Associations between salt intake and hypertension were different in ACE genotype of II and ID+DD. Under the logistic models, main and interaction effects were not observed for men, but effects were present in opposite directions for women (main effect of ACE: OR=0.20, p=0.003; interaction effect: OR=1.07, p=0.027). Under the GPLTR model, Bayesian information criterion trees included both salt intake and ACE genotype as split variables. Individuals with a salt intake ≥19.5 g/day and ID+DD genotypes had a 3.99-fold (p=0.004) higher risk of hypertension compared with the II genotype for men, whereas salt intake <20.1 g/day and ID+DD genotypes had an OR=0.55 (p=0.014) compared with the II genotype for women. An interaction of ACE genotype and salt intake on hypertension was observed among Chinese Kazakhs but in different ways according to sex. The GPLTR model appears to be more suitable for an exploration of interactions in complex diseases. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Nitrogen Cycling and Bacterial Diversity in Hot and Cold Desert Stream Margins

NASA Astrophysics Data System (ADS)

Zeglin, L. H.; Vesbach, C. D.; Dahm, C. N.; Barrett, J. E.; Gooseff, M. N.

2006-12-01

Desert environments offer harsh conditions for life. By definition, water is an extremely limiting resource in any desert. Also, the range of temperatures with which desert life must cope is extreme. Finally, essential nutrients like nitrogen (N) are available in very low amounts relative to temperate environments. Thus, desert organisms are subject to severe stresses like desiccation, temperature stress and starvation. Here, we review the N biogeochemistry of two desert stream systems: the Onyx River, Wright Valley, Victoria Land, Antarctica and the Rio Salado, Sevilleta National Wildlife Refuge, New Mexico, USA. Annually, the Antarctic system receives <100 mm precipitation and is subject to mean temperature ranges of -30 to -15 C. The Rio Salado, in the northern Chihuahuan desert, receives an average of 250 mm precipitation per year and experiences average temperatures from 1.5 to 25 C. The most important sources and sinks of the major forms of N at these sites are contrasted and biogeochemical processes controlling these pools discussed. Nutrient gradients and bacterial diversity patterns in the parafluvial zone of these streams are used to illustrate relationships between biological diversity, environmental stress and N biogeochemistry in the hot and cold desert systems.