Extreme Arid Conditions Research Articles

The Effectiveness of Moringa Oleifera Seed Powder and Mixing Time (Fast-Low Speed) Using Jartest in Reducing Nitrate Levels in River Water

Background:Moringa oleiferais a fast-growing, long-lived plant that blooms throughout the year and can withstand extreme arid conditions. Objective:This study aims to examine the effectiveness of Moringa oleiferaseed powder in reducing nitrate levels in river water. Method:The research method employed in this study involved analysis using the Paired Sample Statistical Test. Result:The statistical test results revealed a significance value of 0.017 (p < 0.05) and a mixing time variation significance of 0.011 (p < 0.05). These values indicate that the null hypothesis (H0: there is no relationship between the independent and dependent variables) is rejected, while the alternative hypothesis (Ha: there is a relationship between the independent and dependent variables) is accepted. This implies a significant difference in the reduction of nitrate levels between the pretest and posttest data, demonstrating that the use of Moringaseed powder is effective in reducing nitrate levels. Conclusion:This study concludes that the administration of Moringaseed powder at a dose of 400 mg/L, with a mixing time of 2 minutes at a fast speed (80 rpm) and 20 minutes at a low speed (40 rpm), is most effective in significantly reducing nitrate levels in river water. Keywords:Moringa oleifera; nitrate levels; river water; Indonesia

Thermal imaging from UAS for estimating crop water status in a Merlot vineyard in semi-arid conditions

AbstractThermal remote sensing indicators of crop water status can help to optimize irrigation across time and space. The Crop Water Stress Index (CWSI), calculated from thermal data, has been widely used in irrigation management as it has a proven association with evapotranspiration ratios. However, different approaches can be used to calculate the CWSI. The aim of this study is to identify the most robust method for estimating the CWSI in a commercial Merlot vineyard using high-resolution thermal imaging from Unoccupied Aerial Systems (UAS). To that end, three different methods were used to estimate the CWSI: Jackson’s model (CWSIj), Wet Artificial Reference Surface (WARS) method (CWSIw), and the Bellvert approach (CWSIb). A simpler indicator calculated as the difference between canopy and air temperature (Tc–Ta) was the benchmark to beat. The water status of a vine cultivar with anisohydric behavior (Merlot) in a vineyard in central Spain was assessed for two years with different agroclimatic conditions. Canopy temperature (Tc) was obtained from UAS flights at 9:00 h and 12:00 h solar hour over eight days during the irrigation period (June–August), and from vines under five different irrigation treatments. Stem water potential (SWP), stomatal conductance (gs), and leaf temperature (TL) were recorded at the time of the flights and compared with the thermal indices (CWSIj, CWSIw, CWSIb) and the benchmark indicator (Tc–Ta). Results show that the simpler indicator of water stress, Tc–Ta, performed better at identifying varying levels of crop hydration than CWSIb or CWSIw at 12:00 h. Under conditions of extreme aridity, the latter indices were less accurate than the physically-based CWSIj at 12:00 h, which had the highest correlation with SWP (r = 0.84), followed by the benchmark index Tc–Ta (r = 0.70 at 12:00). Considering the current climatic trends towards aridification, the CWSIj emerges as a useful operational tool, with robust performance across days and times of day. These results are important for irrigation management and could contribute to improving water use efficiency in agriculture.

A preliminary survey of the cellular responses of the black fungus Cryomyces antarcticus to long and short-term dehydration.

The McMurdo Dry Valleys in Southern Victoria Land, Antarctica, are known for their extreme aridity, cold, and nutrient-poor conditions. These valleys provide a valuable comparison to environments on Mars. The survival of microorganisms in these areas hinges on their ability to withstand dehydration due to the limited availability of liquid water. Some microorganisms have adapted to survive extended periods of metabolic inactivity and dehydration, a physiological response to the harsh conditions in which they exist. This adaptation is significant for astrobiology studies as it allows for testing the resilience of microorganisms under extraterrestrial conditions, exploring the boundaries and potential for life beyond Earth. In this study, we examined the survivability, metabolic activity, cellular membrane integrity, and ultrastructural damage of Cryomyces antarcticus, a eukaryotic organism used for astrobiological studies, following two dehydration processes. We conducted a fast dehydration process, simulating what happens on the surface of Antarctic rocks under typical environmental conditions, and a slow dehydration process, which is commonly used in astrobiological experiments. Our findings revealed a higher percentage of damaged cells following slow dehydration treatments, confirming that rapid dehydration reflects the adaptability of microorganisms to respond to sudden and drastic changes in the Antarctic environment.

Environmental, industrial, and health benefits of Moringa oleifera

AbstractThe rise of air, water, and soil pollution poses a significant threat to global health, leading to widespread disease and premature mortality. Soil health is vital, ensuring the production of safe food, but it is compromised by pollutants such as heavy metals, pesticides, plastics, and excessive fertilization, resulting in the depletion of beneficial microorganisms and subsequently groundwater contamination. Water bodies are polluted due to contamination from industrial effluents, domestic wastewater, agricultural runoff, and oil spillage, further intensifying environmental pollution. On the other hand, atmospheric pollution, characterized by high emissions of gases, volatile compounds, greenhouse gases, not only impacts the climate but also poses serious risks to human health, leading to respiratory diseases, cardiovascular issues, and increased cancer risks. Thus, the strategic utilization of traditional plants emerges as a potent tool for environmental restoration and improving human health. The plants possess natural filtering capabilities, absorbing pollutants from air, soil, and water, thus mitigating their adverse effects. Through phytoremediation, plants can be actively used to extract and remove contaminants, contributing to detoxification and improving water and soil quality. Additionally, plants offer various health benefits. Moringa oleifera or the drumstick plant belonging to the Moringaceae family is one such indigenous plant with wide applications, that can be grown in extreme arid conditions. Since ancient times, this plant has been used for treating skin infections, anaemia, and blood impurities. This plant thrives in diverse climates addressing over 300 different aliments. Rich in phytochemicals and bioactive compounds, M. oleifera serve as a superfood, offering high nutritional values and exhibiting potential for drug development with fewer side effects. Extensive research has elucidated the diverse properties and applications of M. oleifera, however, in-depth research is needed to identify bioactive molecules, phytochemicals, and protein compounds involved, which will aid in understanding of the mechanisms of action of the plant's diverse functions. Although studies have reported several of individual M. oleifera attributes, there is no comprehensive study available addressing its diverse applications. This review covers the findings of past three decades and provides a detailed outline of M. oleifera plant and its various parts, its applications in environmental, industrial, food and health aspects documented to date.

Seasonal water sources and response to precipitation events of Calligonum mongolicum at the oasis margin in the Hexi River Corridor

AbstractCalligonum mongolicum is often planted as a windbreak and for sand stabilization on mobile and semi‐mobile sand dunes in extremely arid regions. However, water availability remains a key limiting factor for its survival and population expansion, and water use strategies and responses to precipitation events of this species are unknown. Here, we determined water use strategy of C. mongolicum under extreme arid conditions by measuring the oxygen stable isotopes (δD and δ18O) in xylem water and in potential water sources (precipitation, soil water, and groundwater). We used the IsoSource model to determine the relative contributions of different water sources to water utilization by C. mongolicum. Our results showed that: (1) water sources used by C. mongolicum exhibited seasonal variability, with shallow soil water accounting for 42% of utilization during early spring (April), and deep soil water and groundwater being predominantly used during the summer and autumn and accounting for 61%–84% of utilization, (2) C. mongolicum did not respond to small precipitation events, but responded significantly to large precipitation events. C. mongolicum maintained the utilization of soil water in all layers at 74%–81% of deep soil water and groundwater before a 5.8 mm precipitation event. A precipitation event of 18.8 mm increased the contribution of surface water from 4% before to 17% after precipitation, indicating that C. mongolicum has a strong capacity for self‐regulation and adaptation; namely, C. mongolicum is capable of developing an optimal phenotype through self‐regulation, thereby maximizing water acquisition.

Long-term rainfall forecasting in arid climates using artificial intelligence and statistical recurrent models

Rainfall is a major component of the hydrologic cycle and thus requires a comprehensive understanding of its dynamics and variability. This study aims to develop and test the applicability of recurrent models for forecasting rainfall in extremely arid regions on a monthly time scale. Specifically, Neural Auto-regressive Networks (NARs) and Auto-regressive Integrated Moving Average (ARIMA) were utilized for modeling a rainfall dataset from Kuwait City from 1958 to 2018. The study site possesses extreme arid conditions with long-term average annual rainfall of less than 120 mm. This harsh condition imposes challenges on modeling efforts. The results of the modeling showed that the NAR model was more efficient in modeling rainfall dynamics over the study period. A notable bias was encountered in models within abnormal wet seasons. The results of the modeling efforts presented in this study were found to be reasonable, and they qualify the NAR model for making objective rainfall forecasts in the study area and other similar climatic zones. The overall Nash–Sutcliffe (NS) coefficient was found to be 0.206 for the NAR model, with the model showing an even better performance within the medium-to-low rainfall intensity months (<30 mm per month). With the outcome of this study, an operational framework for water managers is presented for arid and hyper-arid zones to aid in developing resilient and efficient water management plans to cope with the adverse impacts of climate change.

Divergent Fungal Community Dynamics of Thuja sutchuenensis in Arid Environments.

Thuja sutchuenensis Franch., an endangered species sparsely distributed in the mountainous and arid regions of southwest China, faces the critical challenge of adapting to these harsh conditions. Understanding the plant's strategies for survival and the precise roles played by soil fungal communities in this adaptation remains an area of limited knowledge. Our investigation centers on the fungal communities associated with T. sutchuenensis and their interactions with soil water content. Notably, we identified unique fungal communities in the low soil moisture group, and these communities exhibited lower coverage but higher phylogenetic diversity (PD), Chao1, and Shannon indices compared to other groups. Network analysis revealed a modular structure within the fungal communities, with key hub nodes identified, particularly in the arid group. This group demonstrated higher levels of soil saprotrophs and ectomycorrhizal fungi and a reduced presence of plant pathogens. Linear discriminant analysis highlighted the significance of genera such as Russula, Myxotrichaceae, and Sebacina, emphasizing their roles in supporting the plant in arid environments. Random forest analysis indicated that soil moisture content emerged as the primary driver in determining fungal composition and diversity and contributed to the variables of several fungal genera. Collectively, this study provides valuable insights into the fungal communities associated with T. sutchuenensis, shedding light on their adaptation to extreme arid conditions.

Genomic analysis of Nigerian indigenous chickens reveals their genetic diversity and adaptation to heat-stress

Indigenous poultry breeds from Africa can survive in harsh tropical environments (such as long arid seasons, excessive rain and humidity, and extreme heat) and are resilient to disease challenges, but they are not productive compared to their commercial counterparts. Their adaptive characteristics are in response to natural selection or to artificial selection for production traits that have left selection signatures in the genome. Identifying these signatures of positive selection can provide insight into the genetic bases of tropical adaptations observed in indigenous poultry and thereby help to develop robust and high-performing breeds for extreme tropical climates. Here, we present the first large-scale whole-genome sequencing analysis of Nigerian indigenous chickens from different agro-climatic conditions, investigating their genetic diversity and adaptation to tropical hot climates (extreme arid and extreme humid conditions). The study shows a large extant genetic diversity but low level of population differentiation. Using different selection signature analyses, several candidate genes for adaptation were detected, especially in relation to thermotolerance and immune response (e.g., cytochrome P450 2B4-like, TSHR, HSF1, CDC37, SFTPB, HIF3A, SLC44A2, and ILF3 genes). These results have important implications for conserving valuable genetic resources and breeding improvement of chickens for thermotolerance.

Assessing Water-Saving Technologies and the Impact of Giant Tortoise Herbivory on the Restoration of Opuntia megasperma var. orientalis on Española Island—Galapagos

The prickly pear (Opuntia megasperma var. orientalis), a pivotal species for the ecological balance of Española Island in Galapagos, has witnessed a severe decline in its population due to the enduring presence of introduced feral goats over several decades. Additionally, the inherent slow recovery of this species, requiring several years of development, has contributed to its population decline. Several attempts were carried out to restore this species, but they were not successful due to the island’s extreme arid conditions. Subsequently, innovative water-saving technologies were introduced to ensure the survival and growth of the Opuntia species. Two water-saving technologies, Groasis Waterboxx® and Hydrogel, were applied in two distinct treatments, the first involving Waterboxx solely, and the second combining Waterboxx with Hydrogel, alongside a control group. Planting involved two types of cacti: cladodes and seedlings. To safeguard against potential damage from giant tortoises and local birds, protective mesh fencing was installed around the plants. Each monitoring session recorded plant survival and growth, evaluating the impact of water-saving technologies on cactus survival, maximum plant height reached, age at the time of plant death, and growth achieved since planting. Additionally, the study assessed the influence of climate on plant survival and growth. Unfortunately, the employment of protective mesh fences and Waterboxx containers resulted in the unintended loss of specific bird species. Consequently, a decision was taken to remove these protective measures, resulting in a substantial rise in herbivorous activity, and the subsequent mortality of nearly all plants. Our findings underscore the efficacy of water-saving technologies in Opuntia restoration. However, successful application necessitates a better understanding of these technologies within the unique conditions of the island. Future endeavors should focus on refining these techniques to minimize avian mortality while fostering biodiversity and restoring ecological equilibrium.

Analysis of crack evolution of expansive soil embankment under extreme arid climate

With the increasing impact of global climate change, the frequency of extreme arid climates worldwide is rising. These extreme arid conditions can have adverse effects on expansive soil embankments. In this study, the digital image technology is used to study the crack development characteristics of expansive soil embankments. The findings indicate that the crack development process in expansive soil can be divided into three stages: slow development, rapid development, and stable development. During the drying process, cracks develop differently on the waterward side, the top of the embankment, and the backwater side of the embankment. Initially, cracks appear on the top of the embankment, and their degree of development is the highest in this area. The crack degree on the top of the embankment is approximately 2 to 3 times greater than that on the waterward and backwater sides. Furthermore, longitudinal cracks on the top of the embankment have been analyzed from both macro and micro perspectives. This study is expected to help analyze the underlying formation mechanisms of desiccation cracking-inducing geohazards and access the long-term performance of expansive soil embankments in arid climates.

Leaf Morphological and Epidermal Traits Variability along an Environmental Gradients in Ten Natural Populations of Pistacia lentiscus.

The species belonging to the genus Pistacia possess ecological, economic, and medicinal value. They show a very high ecological plasticity. This research is a contribution to the study of the intraspecific diversity and variability of 10 populations of Pistacia lentiscus in different bioclimates. Nine locations in Algeria and one site in France have been selected in order to understand the strategies developed by this species under extreme conditions, including altitude and aridity, and to identify the adaptive processes that can be observed based on the morphological and ultrastructural features of the leaf. As a result of this research, we have collected a large quantity of important information on morphological and microphytodermal leaf variability for the ten studied populations. The statistical analyses showed a very important difference in the studied characteristics between these populations. It has been demonstrated that environmental factors also have a significant impact on the heterogeneity of most measured leaf features. Moreover, the observations with the scanning electron microscope (SEM) enabled us to highlight new characteristics of the studied species, such as the glandular trichomes on the leaflets and embedded stomata in the epidermis. These criteria could supplement the existing morphological characteristics used in the systematic classification of the Pistacia genus. Overall, the studied species have shown xeromorphy features, which give them the opportunity to be used in desertification mitigation programs, due to their ability to withstand conditions of extreme aridity.

Vertical organization of microbial communities in Salineta hypersaline wetland, Spain.

Microbial communities inhabiting hypersaline wetlands, well adapted to the environmental fluctuations due to flooding and desiccation events, play a key role in the biogeochemical cycles, ensuring ecosystem service. To better understand the ecosystem functioning, we studied soil microbial communities of Salineta wetland (NE Spain) in dry and wet seasons in three different landscape stations representing situations characteristic of ephemeral saline lakes: S1 soil usually submerged, S2 soil intermittently flooded, and S3 soil with halophytes. Microbial community composition was determined according to different redox layers by 16S rRNA gene barcoding. We observed reversed redox gradient, negative at the surface and positive in depth, which was identified by PERMANOVA as the main factor explaining microbial distribution. The Pseudomonadota, Gemmatimonadota, Bacteroidota, Desulfobacterota, and Halobacteriota phyla were dominant in all stations. Linear discriminant analysis effect size (LEfSe) revealed that the upper soil surface layer was characterized by the predominance of operational taxonomic units (OTUs) affiliated to strictly or facultative anaerobic halophilic bacteria and archaea while the subsurface soil layer was dominated by an OTU affiliated to Roseibaca, an aerobic alkali-tolerant bacterium. In addition, the potential functional capabilities, inferred by PICRUSt2 analysis, involved in carbon, nitrogen, and sulfur cycles were similar in all samples, irrespective of the redox stratification, suggesting functional redundancy. Our findings show microbial community changes according to water flooding conditions, which represent useful information for biomonitoring and management of these wetlands whose extreme aridity and salinity conditions are exposed to irreversible changes due to human activities.

Metabolites Facilitating Adaptation of Desert Cyanobacteria to Extremely Arid Environments.

Desert is one of the harshest environments on the planet, characterized by exposure to daily fluctuations of extreme conditions (such as high temperature, low nitrogen, low water, high salt, etc.). However, some cyanobacteria are able to live and flourish in such conditions, form communities, and facilitate survival of other organisms. Therefore, to ensure survival, desert cyanobacteria must develop sophisticated and comprehensive adaptation strategies to enhance their tolerance to multiple simultaneous stresses. In this review, we discuss the metabolic pathways used by desert cyanobacteria to adapt to extreme arid conditions. In particular, we focus on the extracellular polysaccharides and compatible solutes biosynthesis pathways and their evolution and special features. We also discuss the role of desert cyanobacteria in the improvement of soil properties and their ecological and environmental impact on soil communities. Finally, we summarize recent achievements in the application of desert cyanobacteria to prevent soil erosion and desertification.

Extreme arid conditions: Association among soiling characteristics, transmittance loss and climatic conditions

Because of the massive increment in solar plants located in extreme environments, studying the association of climate parameters and soiling in natural conditions has been necessary. In this work, solar glass coupons were exposed to environmental conditions in Salvador solar plant, in the Atacama Desert, during summer and winter campaigns. The soiling was quantified and characterized, and the degradation of optical properties of soiled coupons was also measured. Regarding the reduction of the optical properties of the glass coupons, it was observed that the detrimental effect was higher in summer than in winter. A statical analysis found that this difference in soiling performance is related to the relative humidity and wind speed present in each campaign, mainly due to the daily variations of these parameters. Prolonged periods of relative humidity close to 30% promote the adhesion of particles to the PV glass surface and inhibit their resuspension by the action of the wind, i.e., more dust mass accumulates. Since the effect of soiling is more critical during the summer period, the use of a preventing soiling mitigation system is highly encouraged, and the adjustment of the cleaning schedule according to the seasonality of soiling.

Structural responses of differentially adapted Cenchrus setigerus Vahl ecotypes to water deficit

Two ecotypes of Cenchrus setigerus Vahl (birdwood grass) were collected from dry mountains surrounding hyper-saline Kalar Kahar Lake and Gatwala artificial forest plantation. The ramets of the two ecotypes were established in pots for 15 days and then subjected to 100% FC (control) or 75% and 50% FC (field capacity) levels. Growth attributes such as plant height, tillers per plant, leaves per plant, shoot fresh and dry weights were severely affected while root length was the only attribute that increased in both ecotypes under moisture stress. Root anatomical attributes like cortical and pith parenchyma, and vascular region thickness increased in both ecotypes under water stress. Root radius increased in the Faisalabad ecotype at 75% FC, while increased in Salt Range ecotype only at 50% FC. Stem cellular region, sclerenchymatous cell area, vascular bundle area and metaxylem area increased significantly under moderate and severe water deficit only in the Faisalabad ecotype. The Salt Range ecotype exhibited intensive sclerification and large vascular tissue at 50% FC. Leaf anatomical attributes like epidermal cell area, bundle sheath thickness, sclerenchyma thickness and its cell area, and, vascular bundles area significantly increased in the Salt Range ecotype with increasing water deficit. The Faisalabad ecotype showed significant increase in vascular bundle area, metaxylem area and adaxial stomatal area. These findings indicated that both C. setigerus ecotypes mainly relied on water conservation and survival rather than maintaining growth and biomass production. The anatomical modifications at root, stem and leaf levels ensured survival of C. setigerus ecotypes in extreme arid conditions. • Growth attributes were severely affected while root length increased under stress • Root radius increased in the Faisalabad ecotype at 75% FC, while at 50% FC in Salt Range ecotype • Stem area, sclerification and vascular bundle area increased only in Faisalabad ecotype • The Salt Range ecotype exhibited intensive sclerification in leaves and large vascular tissue at 50% FC • The Faisalabad ecotype showed an increase in vascular bundle area, metaxylem area and adaxial stomatal area

Fungicides and Bacillus subtilis against fungi isolated from commercial seed of Side oats grama (Bouteloua curtipendula)

Banderita (&lt;em&gt;Bouteloua curtipendula&lt;/em&gt;), produces abundant and appetizing forage for cattle under extreme arid conditions. The demand for its seed in Mexico is a direct function of the potential for the establishment of pastures and therefore, the sanitary quality of this is fundamental. Phytopathogenic fungi affect the seed and establishment of prairies. The objective was to evaluate&lt;em&gt; in vitro&lt;/em&gt; the effect of six agrochemicals and one biological against fungi associated with Banderita seed, to reduce losses caused by these. Treatments were carried out in PDA culture medium combined with Captan, Thiophanate-methyl, Mancozeb, Benomil, Prochloraz, Thiabendazole and &lt;em&gt;Bacillus subtilis&lt;/em&gt; at concentrations according to the case of 0 (control), 0.005, 0.001, 0.05, 0.01, 0.5, 0.1, 1.5, 10, 100, 150, 200, 250 and 300 mg L-1, against &lt;em&gt;Alternaria alternata&lt;/em&gt;, &lt;em&gt;Bipolaris cynodontis&lt;/em&gt; and &lt;em&gt;Fusarium incarnatum&lt;/em&gt;. The bi-directional colony diameter was measured every 48 h. The effective concentration of 50% was estimated by a non-linear regression model; in relation to the percentage of inhibition of mycelial growth. &lt;em&gt;Bacillus subtilis&lt;/em&gt; presented higher mycelial inhibition 97% (P &amp;lt;0.05), followed by Thiophanate-methyl (96%), Prochloraz (94%), Captan (93%) and Mancozeb (92%). Benomyl and Thiabendazole showed low inhibition of fungi with 46 and 37%.&lt;em&gt; B. subtilis&lt;/em&gt; and Thiophanate-methyl are the products with the greatest possibility of controlling pathogens associated with Banderita grass seeds.

Arbuscular mycorrhizal fungal abundance in elevation belts of the hyperarid Atacama Desert

Arbuscular mycorrhizal (AM) fungi affect ecosystem processes improving plant tolerance in (hyper)arid/saline environments. However, there are no previous studies on the presence of AM fungi in the Atacama Desert (Northern Chile), the driest desert in the world. Here, we studied the root and rhizosphere in 111 samples of representative plants from three elevation gradients: (i) hyperarid desert (700–2000 m a.s.l.), (ii) pre-Puna (2000–3100 m a.s.l.) and (iii) Puna (3100–4500 m a.s.l.) elevation belts. Soil pH, electrical conductivity (EC), organic matter, cations and the AM colonization and fungal structures were determined. All plants showed colonization and fungal structures. Root colonization ranged from 3.5 to 87%, hyphae showed densities from 0.13 to 204 m g −1 , and spore densities between 20 and 45,500 per 100 g of soil. The highest fungal structure abundances were found in Prosopis tamarugo , Baccharis scandens , Werneria pinnatifida , Deyeuxia curvula and Festuca deserticola rhizospheres. In general, EC and cations showed strong relationship with fungal structure abundance. Here, we reported for the first time the widespread presence of AM symbiosis in all the elevation belts of the Atacama Desert, constituting a first step to understand the ecological role that AM fungi play under extreme aridity and salinity conditions.

Toward an Integrated and Sustainable Water Resources Management in Structurally-Controlled Watersheds in Desert Environments Using Geophysical and Remote Sensing Methods

Sustainable water resources management in desert environment has yet to be reached due to the limited hydrological datasets under such extreme arid conditions. In the Eastern Sahara, the tectonic activity associated with the opening of the Red Sea adds more complexity to developing sustainable water management by creating multiple aquifers within subsided half-grabens along the Red Sea extension. To overcome these difficulties, a two-fold approach is adopted including integrated remote sensing and geoelectrical methods using Wadi Al-Ambagi watershed in the Eastern Desert of Egypt as a test site. First, the total discharge is estimated as 15.7 × 106 m3 following the application of a uniform storm of 10 mm effective precipitation, which exceeds the storage capacity of existing mitigation measures (5.5 × 106 m3), and thus additional dams are required. Second, the subsurface geometry of alluvium and sedimentary aquifers, within subsided blocks in the Arabian–Nubian shield (ANS), is delineated using 1D direct current and 2D electrical-resistivity tomography (ERT). Findings indicate that significant thicknesses of more than 80 m of permeable sedimentary units occur within the subsided blocks. Therefore, the scarce water resources can be managed by controlling the flash floods and suggesting proper dam sites at the location of thick alluvium and sedimentary rocks, where aquifers can be recharged representing a sustainable source for freshwater. The proposed approach is transferable and can be applied in similar arid rift-related watersheds in Saudi Arabia and worldwide.

The Survival of Aboriginal Australians through the Harshest time in Human History: Community Strength

AbstractIntroduction: Aboriginal People have inhabited the Australian continent since the beginning of time, but archaeologists and anthropologist’s state there is evidence for approx. 51,000 to 71,000 years of continual habitation. During this time, the Australian continent has experienced many environmental and climatic changes i.e. fluctuating temperatures, ice ages, fluctuating CO2 levels, extremely high dust levels, high ice volume, high winds, large scale bush fires, glacial movement, low rain fall, extreme arid conditions, limited plant growth, evaporation of fresh water lakes, and dramatic sea level fluctuations, which have contributed to mass animal extinction.Method: The skeletal remains of Aboriginal Australians were examined for evidence of bone spurring at the calcaneus, which may be indicative of fast running which would assist survival. The skull and mandible bones were examined for signs evolutional traits related to survival. Aboriginal culture, knowledge of medical treatment and traditional medicines were also investigated. Discussion: Oral story telling of factual events, past down unchanged for millennia contributed to survival. Aboriginal Australians had to seek refuge, and abandon 80% of the continent. Physical ability and athleticism was paramount to survival. There is evidence of cannibalism by many Aboriginal Australian tribes contributing to survival. The Kaurna People exhibited evolutionary facial features that would have assisted survival. Kaurna People had excellent knowledge of medicine and the capacity to heal their community members.Conclusion: The Australian continent has experienced many environmental and climatic changes over the millennia. Navigating these extremely harsh, rapidly changing conditions is an incredible story of survival of Aboriginal Australians. The findings of this investigation suggest that Aboriginal Australians survival methods were complex and multi-faceted. Although this paper could not examine every survival method, perhaps Aboriginal Peoples knowledge of flora and fauna, for nourishment and medicine, was paramount to their survival.

Impact of spatial patterns on arthropod assemblages following natural dune stabilization under extreme arid conditions

Background: The cessation of anthropogenic activities in mobile sand dune ecosystems under xeric arid conditions has resulted in the gradual stabilization of dunes over the course of five decades. Our objective was to analyze the spatial patterns of arthropod assemblages along a gradient of different stabilization levels, which represents the different stages of dune stabilization - from the shifting crest of the dune to the stabilized crusted interdune. The study was carried out at the sand dunes of the northwestern Negev in Israel. Data was collected using dry pitfall traps over two consecutive years during the spring along northern windward aspects. Four dunes were chosen, characterized by three significant landscape units: shifting crest, semi-stabilized slope and stabilized interdune. Results: We identified three significant assemblages of arthropods along the gradient. The shifting dune crests are populated by psammophilic species found almost exclusively in sandy habitats in Egypt and the western Negev in Israel. The crusted, stabilized inter-dunes are populated mainly by loess-dwelling species, which are common in most of the Negev loess plains and have a wide distribution range, and the semi-stabilized slopes host species of both extreme landscape units but is distinguished by four species that show significant affinity to it. Conclusions: Our results demonstrate functional arthropod heterogeneity and emphasize the risk of regional species homogenization. Heterogeneity is a key property in maintaining sand dune biodiversity. Homogenization, as a result of sand stabilization, may lead to loss of psammophilic species.