Southern Desert Research Articles

Dust storms in Central Asia: Spatial and temporal variations

Dust/sand storms are common events in the arid and semi-arid regions of Central Asia. The region is characterized by strong winds, scarcity of vegetation cover, continental climate with long and dry summers, frequent soil and atmospheric droughts. Central Asian drylands, covered by a great variety of desert types, represent a powerful source of mineral and salt aerosols.The main objectives of this study are to monitor and assess the spatial and temporal distribution of dust storms over the Central Asian region during the last seven decades. The identified active source areas of dust storms are located mainly in the sandy deserts and other types of deserts where the sensitive ecosystems suffered from human impact. The main persistent sources of dust storms are located in the large “dust belt” that extends from west to east over the southern deserts, north of Caspian Sea deserts, south of Balkhash Lake, and Aral Sea region. The results of the analysis show a significant decrease in dust/sand storm frequency during the last decades and considerable changes in the active source areas.

Effects of some seed-coat dormancy breaking treatments on germination of three Calligonum species occurring in Southern desert of Tunisia

The germination response of three Calligonum species (C. azel Maire, C. arich Le Houérou et C. comosum L’Hérit.) to mechanical, physical and chemical scarifications, applied for overcoming dormancy, has been studied under controlled conditions. The above-mentionned speceis are three dominant and economically important species widely distributed in active sand dunes in the Eastern Great Erg of Tunisia. In all three Calligonum species, the germination of the untreated (control) seeds was relatively low, indicating the presence of coat-imposed dormancy in a fraction of the studied seeds. Chemical scarification with sulphuric acid (96%) was effective in breaking seed dormancy and consequently in increasing the rate and the final percentage of germination. However, treatments with sulphuric acid above 20 min significantly decreased the amount of dead seeds. Compared to other pretreatments, the 20-30 min acid treatments for C. azel and C. arich and boiling water or 30 min acid treatment for C. comosum decreased the number of days to first germination by 2-6 days. Overall, this study demonstrated that physical dormancy caused by impermeable seed-coat appeared to be the main reason of the low germination level of the untreated seeds. The 30-min sulphuric acid (96%) treatment was the most suitable in breaking the seed dormancy and enhancing the germination of Calligonum species.

Impacts on Ambient Air Quality Due to Flaring Activities in One of Oman's Oilfields

ABSTRACT This work was conducted to assess the impacts on workplace and ambient air quality due to release of sulfur dioxide (SO2) into the atmosphere at Al-Noor production station, located in southern desert of Sultanate of Oman. The SO2 is released because of oxidation of H2S to SO2 on flaring of H2S rich off gas at the Al-Noor. In the first phase of the study, CALPUFF modeling system was used to predict the ground level concentrations of SO2 emissions from the flare stacks. The evaluation of the modeling system was carried out by comparing the predicted results with that of the measured. In the second stage of the study, the estimated results were compared with the air quality standards/guidelines set by Omani regulatory authorities as well as by World Health Organization (WHO). It was concluded on the basis of current study that the sensitive individuals in the workplace of the Al-Noor could experience adverse health effects due to short-term exposure of SO2.

Occurrence and characteristics of Quaternary calcareous microbialitic crust in the southern desert of Kuwait, Arabian Gulf

Calcareous microbialitic laminated thin crust coated calcareous sandstone rocks occurs within depressions in the southern desert of Kuwait. It is few millimeters thick and consists of alternating dark colored calcareous laminae and light colored detritus-rich clayey laminae. Both types of laminae include calcified cyanobacteria and their extracellular polysaccharides (EPS). Authigenic calcite spicules and platelets of micron size agglutinated on EPS are the main constituents of the calcareous laminae. Calcareous and clayey laminae include detrital silt size quartz, feldspars and calcite grains. Alternation of calcareous and detrital-rich laminae, organosedimentary structures, and mineralogy of this crust may suggest that it has been developed as a result of the interaction between micro-organisms (cyanobacteria) and physiochemical conditions during successive wet and dry periods.

The identification of distinct patterns in California temperature trends

Regional changes in California surface temperatures over the last 80 years are analyzed using station data from the US Historical Climate Network and the National Weather Service Cooperative Network. Statistical analyses using annual and seasonal temperature data over the last 80 years show distinctly different spatial and temporal patterns in trends of maximum temperature (Tmax) compared to trends of minimum temperature (Tmin). For trends computed between 1918 and 2006, the rate of warming in Tmin is greater than that of Tmax. Trends computed since 1970 show an amplified warming rate compared to trends computed from 1918, and the rate of warming is comparable between Tmin and Tmax. This is especially true in the southern deserts, where warming trends during spring (March–May) are exceptionally large. While observations show coherent statewide positive trends in Tmin, trends in Tmax vary on finer spatial and temporal scales. Accompanying the observed statewide warming from 1970 to 2006, regional cooling trends in Tmax are observed during winter and summer. These signatures of regional temperature change suggest that a collection of different forcing mechanisms or feedback processes must be present to produce these responses.

Assessing the invasive potential of the Mediterranean fruit fly in California and Italy

The polyphagous tropical Mediterranean fruit fly (Ceratitis capitata Weid. (medfly)) was detected in California in 1975, and a large-scale detection/eradication campaign was begun in the absence of sound knowledge of the fly’s potential invasiveness and geographic distribution. Persistent measurable populations of the fly have not been found in California, but a scientific explanation for this has not developed. A physiologically based demographic system model (CASAS) was developed to examine the effects of temperature on medfly’s potential distribution across the ecological zones of Arizona–California (AZ–CA), and in Italy where the fly is established. The system model simulates the daily age-mass structured dynamics of a tree host composed of sub-unit populations of leaves, stem, roots and fruit, as well as the age-structured dynamics of medfly life stages. Total pupae tree−1 year−1 was used as the metric of favorability for medfly at 151 locations in AZ–CA during 1995–2006, and at 84 locations in Italy during 1999–2005. The results were mapped using GRASS GIS. AZ and the southern desert areas of CA are unfavorable for medfly because of high summer temperatures, while much of CA, including many frost-free areas, is too cold. Only the area of south coastal CA (San Diego, Orange and Los Angeles Counties) is potentially favorable for medfly, but in the absence of measurable populations, we cannot say whether it is established there. The majority of medfly discoveries over the past 35 years have occurred in south coastal CA, but discoveries also occurred in Santa Clara County in northern CA, mostly during 1975 and 1980–1981. Santa Clara County, just south of San Francisco Bay, is generally marginal for medfly, but favorability increased approximately 10% during the period 1979–1981. Medfly has been established in Italy for decades, and our model predicts its wide distribution in the southern and western regions of the country. The fly is restricted in northern areas and at higher elevations of Italy by winter temperatures. Temperature is expected to increase in CA and the Mediterranean Basin. We used two scenarios consisting of increasing observed daily temperatures +2 and +3°C to examine the effects on the potential distribution of the fly in CA and Italy. Increasing temperatures expand the favorable range for medfly northward along the coast of CA, but decrease it in the southern reaches of current favorability. A similar but greater increase in geographic range is predicted for Italy. We examine critically some ongoing eradication programs in CA, and question the scientific basis for them. We also review some climate matching approaches used to assess the potential geographic distribution of invasive species.

Research on the Hydrochemical Characteristics of Groundwater at the Southern Edge of Taklimakan Desert and along the Southern Desert Highway, China

In this paper, the characteristics of chemical components of groundwater were analyzed by means of investigating and collecting groundwater samples and hydrochemical analyses in the lower reaches of Niya river, Yatonggusi river and Andier river, the south edge of Taklimakan desert and along the southern desert highway in Tarim basin. It indicates that the total dissolved solids (TDS) in shallow groundwater are respectively 2.14-4.97g•L-1, 5.79-7.71g•L- 1 and 1.21-38.85g•L-1 in Niya river, Yatonggusi river and Andier river. The partial correlationships of groundwater TDS with HCO3-, SO42-, Cl-, and Na+ ions are extremely obvious, the relative coefficients ranging from 0.9598 to 0.9874, and quite obvious to Mg2+, Ca2+ ions with the coefficients of 0.8508 and 0.7771 in the lower reaches of Andier river. For the groundwater TDS along the southern desert highway, its partial correlationships to SO42-, HCO3- and Cl- ions are extremely obvious, with the relative coefficients ranging from 0.9171 to 0.9686, and quite obvious to Na+ and Ca2+ ions with the coefficients of 0.7873 and 0.6322. In the lower reaches of Andier river, there are some spatial correlations on the aspects of K+ and HCO3- contents in groundwater, and the spatial correlation distances in latitude and longitude are 0.03° and 0.21°. Based on the established semivariogram models, isograms of the distribution of ion contents in groundwater were plotted by using Kriging and IDW methods. The results show that the spatial distribution characteristics of chemical components in groundwater are consistent with that of ions contents changing along the latitude from south to north.

Drought analysis in Jordan under current and future climates

Droughts have adverse socioeconomic, agricultural, and environmental impacts that can be reduced by assessing and forecasting drought behavior. The paper presents detailed analyses of both meteorological and vegetative droughts over the period from 1970 to 2005. Standardized Precipitation Index (SPI) and Normalized Difference Vegetation Index (NDVI) have been used to quantify drought according to severity, magnitude and spatial distribution at the Hashemite Kingdom of Jordan. Results suggest that the country faced during the past 35 years frequent non-uniform drought periods in an irregular repetitive manner. Drought severity, magnitudes and life span increased with time from normal to extreme levels especially at last decade reaching magnitudes of more than 4. Generated NDVI maps spatial analyses estimate crop-area percentage damage due to severe and extremely severe drought events occurred during October, December, and February of 2000 to be about 10%, 45%, and 30%, respectively. In response to drought spatial extent, the paper suggest the presence of two drought types, local drought acting on one or more geographical climatic parts and national drought, of less common but more severe, that extend over the whole country. Droughts in Jordan act intensively during January, February and March and tend to shift position with time by alternative migrations from southern desert parts to northern desert parts and from the eastern desert parts to highlands and Jordan Rift Valley (JRV) at the west. The paper also investigates the potential use of Global Climate Model’s (GCM) to forecast future drought events from 2010 till 2040. Tukey HSD test indicates that ECHAM5OM GCM is capable to predicted rainfall variation at the country and suggests future droughts to become more intensive at the northern and southern desserts with 15% rainfall reduction factor, followed by 10% reduction at the JRV, and 5% at the highlands.

Seasonal and spatial trends in the sources of fine particle organic carbon in Israel, Jordan, and Palestine

A study of carbonaceous particulate matter (PM) was conducted in the Middle East at sites in Israel, Jordan, and Palestine. The sources and seasonal variation of organic carbon, as well as the contribution to fine aerosol (PM 2.5) mass, were determined. Of the 11 sites studied, Nablus had the highest contribution of organic carbon (OC), 29%, and elemental carbon (EC), 19%, to total PM 2.5 mass. The lowest concentrations of PM 2.5 mass, OC, and EC were measured at southern desert sites, located in Aqaba, Eilat, and Rachma. The OC contribution to PM 2.5 mass at these sites ranged between 9.4% and 16%, with mean annual PM 2.5 mass concentrations ranging from 21 to 25 ug m −3. These sites were also observed to have the highest OC to EC ratios (4.1–5.0), indicative of smaller contributions from primary combustion sources and/or a higher contribution of secondary organic aerosol. Biomass burning and vehicular emissions were found to be important sources of carbonaceous PM in this region at the non-southern desert sites, which together accounted for 30%–55% of the fine particle organic carbon at these sites. The fraction of measured OC unapportioned to primary sources (1.4 μgC m −3 to 4.9 μgC m −3; 30%–74%), which has been shown to be largely from secondary organic aerosol, is relatively constant at the sites examined in this study. This suggests that secondary organic aerosol is important in the Middle East during all seasons of the year.

Seed germination at different temperatures and water stress levels, and seedling emergence from different depths of Ziziphus lotus

Ziziphus lotus (L.) Lam. is a deciduous shrub with intricately branched stems in the Rhamnaceae family. It's a dominant and economically important species widely distributed in active sand dunes in the southern desert of Tunisia. To provide basic information for its conservation and reintroduction, we studied the influence of environmental factors on seed germination patterns. The germination responses of seeds were determined over a wide range of constant temperatures (10–50 °C), polyethylene glycol (PEG)-6000 solutions of different osmotic potentials (0 to − 1 MPa) and burial depths (1–10 cm). Temperatures between 15 and 45 °C seem to be favorable for the germination of this species. Germination was inhibited by either an increase or decrease in temperature from the most suitable temperature found (35 °C). The highest germination percentages (100%) were obtained under control conditions without PEG, and increasing moisture stress progressively inhibited seed germination, which was less than 5% at − 1 MPa. When tested for germination in distilled water, after PEG treatments, seeds germinated to the same extent as when fresh. When seeds buried deeply, there was a significant decrease in seedling emergence percentage and rate. Seedlings of Z. lotus emerged well at depths of 1–2 cm and could not emerge when sand burial depth was > 4 cm.

California Indians and their environment: an introduction

Preface Acknowledgments RETHINKING CALIFORNIA INDIANS Why California Indians Matter The Central Role of Fire Waves of Migrations A Landscape of Unparalleled Diversity The Uniqueness of California The First Fire Managers They Are Not Farmers Where We Go from Here VISUAL GUIDE TO NATURAL RESOURCES A GUIDE TO CALIFORNIA INDIAN USES OF NATURAL RESOURCES Introduction Northwest Coast Province Central Coast Province South Coast Province Northwest Coast Province Great Central Valley/Sierra Nevada Province Southern Deserts Province Notes Bibliography Art Credits Index

Archaeal populations in biological soil crusts from arid lands in North America

Archaea are common and abundant members of biological soil crust communities across large-scale biogeographic provinces of arid North America. Regardless of microbial community development, archaeal populations averaged 2 × 10 7 16S rRNA gene copies per gram of soil, representing around 5% of the prokaryotic (total calculated bacterial and archaeal) numbers assessed by quantitative-PCR. In contrast, archaeal diversity, determined by denaturing gradient gel electrophoresis fingerprinting and clone libraries of 16S rRNA genes, was very restricted. Only six different phylotypes (all Crenarchaea) were detected, three of which were very dominant. Some phylotypes were widespread, while others were typical of Southern desert areas.

Effects of climate warming on Olive and olive fly (Bactrocera oleae (Gmelin)) in California and Italy

Climate change is expected to alter the geographic distribution and abundance of many species. Here we examine the potential effects of climate warming on olive (Olea europaea) and olive fly (Bactrocera oleae) across the ecological zones of Arizona–California (AZ–CA) and Italy. A weather-driven physiologically-based demographic model was developed from the extensive literature and used to simulate the phenology, growth and population dynamics of both species. Observed weather for several years from 151 sites in AZ–CA and 84 sites in Italy were used in the study. Three climate-warming scenarios were developed by increasing observed average daily temperature 1°, 2° and 3°C. Predictions of bloom dates, yield, total fly pupae and percent infestation were mapped using GRASS GIS. Linear multiple-regression was used to estimate the effects of weather on yield and fly abundance. Olive has a much wider temperature range of favorability than olive fly. The model predicted the present distributions of both species and gave important insights on the potential effects of climate warming on them. In AZ–CA, climate warming is expected to contract the range of olive in southern desert areas, and expand it northward and along coastal areas. Olive fly is currently limited by high temperature in the southern part of its range and by cold weather in northern areas. Climate warming is expected to increase the range of olive fly northward and in coastal areas, but decrease it in southern areas. In Italy, the range of olive is expected to increase into currently unfavorable cold areas in higher elevations in the Apennine Mountains in central Italy, and in the Po Valley in the north. Climate warming is expected to increase the range of olive fly northward throughout most of Italy.

Comparative phenological and water potential patterns of three Calligonum species in the eastern great Erg of Tunisia

Calligonum azel, C. comosum and C. arich (Polygonaceae) are three dominant and economically important species widely distributed in active sand dunes in the southern desert of Tunisia, which differ in growth form and may co-occur under the same climatic constraints. The aims of this work were to compare their phenological and water potential patterns, as well as branch, flower and fruit production during three years at monthly intervals. Predawn ( Ψ pd) and midday ( Ψ md) water potentials followed similar trends with a few exceptions. For all species, Ψ md reached values more negative than −2.5 MPa during the hot and dry summer, with extremes in July. Ψ pd differed between the species, and C. comosum attained the most negative values (−1.71 MPa). Seasonal differences in Ψ pd were less pronounced for Calligonum species established in dunes as compared to C. comosum from interdunes. Spatial and temporal variations in soil water content provoked changes in water potentials of these species. Diurnal amplitudes resulting from the difference between Ψ md and Ψ pd were more pronounced during the dry season compared to the wet months. The phenological pattern of the three species showed a similar sequence of phenophases with growth activity occurring mostly between spring and summer. We found a species-dependent response to summer drought, as C. comosum ended all phenophases in June, while C. azel and C. arich extended their vegetative growth into the summer period of low precipitation. Water availability for the plants was better on the dune slopes. Differences were statistically significant among species, concerning green branch production and numbers of initially formed flowers and mature fruits. Our data suggest that changes in the studied parameters may depend on the rooting depth of the species.

A conservation auction for landscape linkage in the southern Desert Uplands, Queensland

Conservation auctions are a type of market-based instrument (MBI) that can achieve a more cost-efficient allocation of public funds than approaches such as devolved grants. In this paper, the conduct of a multiple round conservation auction to improve biodiversity management in a rangelands area is outlined. The auction was designed to develop a wildlife corridor across the southern Desert Uplands bioregion in Queensland and to improve management of rangelands areas. The conservation auction incorporated two important new design features. First, there was a need to promote landholder cooperation so that proposed areas for better land management were aligned and connected across the region. The second innovative design feature was to hold multiple bidding (three) rounds, which differs from the standard application of a single bidding round. The auction outcomes resulted in conservation contracts covering 85 000 ha of remnant vegetation awarded at an average cost of $2* per hectare per annum. Although complete landscape connectivity across the Desert Uplands was not achieved, over 70% of the successful bids, accounting for over 62 000 ha (77% of the total bid area), were part of a group that formed a distinct corridor or landscape linkage with only single or part-property gaps. The results also indicate that multiple bidding rounds improved auction efficiency (for the government), although there was little improvement in connectivity. Sixty-six percent more environmental benefit units could be purchased for the given budget of $350 000 between rounds one and three.

Mycoflora associated withHyoscyamus muticusgrowing under an extremely arid desert environment (Aswan region, Egypt)

Hyoscyamus muticus L. (Egyptian henbane) is one of the desert medicinal plants of family Solanaceae. The plant produces pharmaceutically important compounds (tropane alkaloids) as secondary metabolites. In the present study, we describe mycoflora of H. muticus grown in four different locations in Egyptian southern desert (Aswan region): Aswan university campus, Wadi Allaqi down stream part, Aswan airport road, and Sahari city. Eighty-one species and two varieties belonging to 31 genera were isolated from soils surrounding H. muticus plants, the surface of the plants, and inside the plants as endophytic fungi. Aspergillus was the most common genus in all study areas. The highest number of genera and species of fungi were recorded in Aswan university campus followed by Aswan airport road. Fungal diversity analysis revealed that these two locations have higher fungal diversity compared to other two locations. A higher number of fungal species were isolated from rhizosphere soil and rhizoplane than from non-rhizosphere and other plant organs. Endophytic fungi were isolated from all plant parts of H. muticus. Communications between H. muticus plants and fungi under desert conditions both in rhizosphere and inside the plant are deduced.

Decline Of Anopheles sergentii and Aedes caspius Populations Following Presentation Of Attractive Toxic (Spinosad) Sugar Bait Stations In An Oasis

The effect of attractive sugar bait stations, including sucrose, juice of nectarine, slow-release substances, preservatives, red food-dye marker, and the oral insecticide spinosad, on Anopheles sergentii and Aedes caspius populations was studied in a small oasis in a southern desert of Israel. Feeding on similar baits without an insecticide was monitored as a control in a similar neighboring oasis. The insecticide caused a drastic decrease in the number of mosquitoes. Compared to the control site, the An. sergentii population was reduced to less than a tenth and that of Ae. caspius declined to a third. The majority of the mosquitoes, 76.0% of An. sergentii females and 74.8% of Ae. caspius females, were marked by the food dye in the control site.

Views on Libyan national plan (LNP) to resolve water shortage problem (WSP). Part Ib: Great Man-Made River (GMMR) project — capital cost with interest rates

Libyan national plan (LNP) to resolve the water shortage problem will be illustrated through a quartet of a series of papers. The first series of papers (I) will deal with Great Man-Made River (GMMR) supplied from rich ground water reservoirs located in the southern desert regions. This paper (Ib) will conduct the cost analysis study by considering the influence of interest rates on capital costs, as compared to the first paper (Ia) which neglected the effect of interest rates and treated capital costs as sunk value. This will improve the ability to analyze the viability and feasibility of this mean in comparison with other means to resolve the water shortage problem.

A new species of Lucasium (Squamata: Diplodactylidae) from the southern deserts of Western Australia and South Australia

– Discoveries of new species of Australian squamaks continue following explorations of remote regions, examination of large series of taxa that differ subtly and through genetic techniques. Here we describe a new species of Lucasium from the southern deserts of Western Australia and South Australia. Lucasium bungabinna sp. nov.

The ion chemistry of surface and ground waters in the Taklimakan Desert of Tarim Basin, western China

The physio-chemical and chemical features of water in natural conditions are controlled by the weathering of bedrocks, local climate, landforms and other geo-environmental parameters. In order to understand the characteristics of water and the origins of the dissolved loads in the rivers and in the ground waters of the Taklimakan Desert, western China, we studied the ions in the water samples collected from rivers and wells. We collected water samples from four rivers (Keriya River, Cele River, Tumiya River and Yulongkashi River) in the southern desert and ground water samples from many parts of the desert. Major cations and anions were measured using ion-chromatograph and titration with HCI. The total dissolved solids (TDS), pH and conductivity were examined on site by a portable multi-parameter analyzer. The data show that the water in the rivers of southern Taklimakan is still of fresh water quality and slight alkalinity, although the TDS is comparatively higher than that of many other rivers of the world. The ground water is fresh to slightly saline, with TDS a little higher than that of river water in the study area. The concentration of ions is slightly different between the four rivers in the southern Taklimakan. However, the chemistries of ground water in all samples are to a large degree controlled by sodium and chloride. The ions in the ground water are concluded to be mainly from dissolving of evaporites, consistent with the dry climate in the region, whereas the ions in the rivers are mainly from rock weathering. Low-level human imprints are recognized in the ground water samples also.