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Background: Orenburg Region is located in the South Urals, mostly in the steppe zone and is characterised by various landscapes suitable for many Chenopodiaceae. The species of Chenopodiaceae are present in all major plant communities (saline vegetation, steppes, on limestone, chalk and sand, and as degraded or ruderal communities). In the steppe zone, many native subshrubby species (Atriplex cana, Caroxylon laricinum, Suaeda physophora) playing a crucial role in semi-deserts (known as southern steppes in the recent Russian literature) located southwards of Orenburg Region are locally found, and several annuals (Salicornia perennans, Suaeda spp.) are most common dominants in plant communities. Some typical semi-desert species (Kalidium foliatum, Bassia hyssopifolia, Soda foliosa, Spirobassia hirsuta) are found in the easternmost part of the region. New information: We compiled a checklist of Chenopodiaceae in Orenburg Region, with two new records ( Chenopodium virgatum, Corispermum laxiflorum), based on our critical revision, comprehensive inventory of herbarium specimens and documented observations and field research. In total, we report 76 species in the Region, which is the third-highest number of the Chenopodiaceae species compared with other administrative territories of European Russia, North Caucasus and West Siberia. Alien and native taxa are distinguished. Zonal patterns of species distributions are confirmed. A preliminary conservation status is proposed for each native species. Three species are recommended for exclusion from the Red Data Book of Orenburg Region: Petrosimonia triandra (because of its extensive distribution), Kalidium foliatum and Anabasis salsa (because of the lack of actual threat to their populations). Arthrophytum lehmannianum and Salsola rosacea are considered threatened (Vulnerable) because of their restricted occurrence and population size and because their localities are under anthropogenic pressure. Atriplex hortensis, Atriplex rosea, Chenopodium acuminatum, C. karoi, C. praetericola, C. vulvaria, Climacoptera affinis, C. crassa, Halimocnemis karelinii, Salsola paulsenii and Xylosalsola arbuscula are excluded from the checklist, based on various reasons as discussed in the paper. Point distribution maps are provided for each species. Agriophyllum pungens (Vahl) Link is accepted as the correct authorship instead of "M.Bieb. ex C.A.Mey." [ABSTRACT FROM AUTHOR]

Given the aesthetic, cultural, ecological, and economic value of the date agro-system in Southwestern Tunisia, different management and conservation strategies have been warrantee to optimize land productivity sustainably. However, the inefficiency of the adopted management actions resulted in a continuous loss of soil fertility and decreasing fruit quality. Thus, the present paper attempts to evaluate accurately the evolution of the principal factors influencing date palm production and agricultural activities sustainability in the region. Integrated approaches of various irrigation water quality indices and geostatistical analysis coupled with field investigation and farming survey were applied to evaluate the evolution of key parameters influencing the development of date palm sustainably. The obtained results of the research indicate that the progressive land degradation is due to the effects of poorquality of water used for irrigation (EC between 674.4 and 5450 µs/cm, SAR exceeding locally 20 and about 80% of all the samples waters are of undoubtful quality according to the calculated indices), inappropriate irrigation scheduling (physiologic drought that might reach 3 months), traditional basin irrigation technique (decreasing of yield productivity, locally of 0.23, 0.23 and 0.25 kg m−3), an indigenous knowledge (sandy amendment, biologic compost, gravity improved irrigation.....). Also climate variability has leaded to furthermore degradation of crop quality. The degradation of date palm culture will be a great challenge for environmental conservation, food security and socio-economic values of the region unless a reasonable management take place, a flexible strategy based on indigenous knowledge of landowner, and scientific-based outlines with climate risks evaluation. The present paper might be useful to policy makers as a multi-disciplinary research covering most of the important aspects of date palm production. [ABSTRACT FROM AUTHOR]

Sand and dust storms (SDS) are a natural phenomenon dominantly originating in arid and semi-arid regions. The vastness and changing distribution of the SDS hotspots, their inaccessibility, and financial limitations are the greatest challenges to projects combating SDS. To boost project success, a prioritized site-selection method which incorporates the physical and human variables interacting with SDS is applied in this paper. This ensures that potential economic and health impacts of SDS on human populations are also included. Six variables were selected for analysis: within-region sand and dust hotspots, changing distribution of the hotspots, residential areas, vegetation cover, soil texture, and the maximum drought-inundation of the Hamoun wetland. SDS hotspot sites for possible stabilization were identified and prioritized using the multi criteria evaluation (MCE) method. Such prioritization assists the practical management of hotspots under conditions of resource and budgetary constraints which are especially common in developing countries. This paper thus provides a template for site selection and prioritization of SDS hotspots for remediation. It also highlights the importance of variables other than SDS source areas for selection of rehabilitation sites. The proposed method, using the Sistan region as an example, is applicable to other regions of the world as a means of reducing the negative effects of known dust storm hotspots. [ABSTRACT FROM AUTHOR]

This paper presents the results of an analysis of trends in variation in the mean monthly air temperature in arid lands in the European part of Russia and adjacent areas in summer; the direction of these trends and the rate of temperature changes in the second half of the 20th and early 21st centuries are estimated. The regional features of the thermal regime in the European part of Russia (EPR) have been studied against the background of global climate change. The latitudinal and longitudinal quantitative indicators of changes in the thermal regime, including their spatial distribution in the study area, are estimated. A significant increase in the air temperature has been recorded in the arid lands of Russia, where the trend in the temperature increase (0.066°C over the 10 years) is much higher than the values obtained from assessment reports. [ABSTRACT FROM AUTHOR]

Intact drylands are highly evolved and complex ecosystems, which allow them to be productive despite harsh environmental conditions. However, drylands are particularly susceptible to degradation, even after minor disturbance events. Conditions for natural plant recruitment in dryland systems are spatially and temporally irregular, which can create challenges for restoration. Large-scale restoration and rehabilitation of dryland ecosystems have become a global concern, prompted by ever-increasing anthropogenic pressure and associated degradation of these natural systems worldwide. The success of plant reestablishment programs in these regions is closely linked to both ecological and socioeconomic opportunities and limitations. This special issue brings together papers that discuss the roles which ecological and socioeconomic factors play in influencing dryland ecosystem restoration outcomes. We aim to (1) highlight the current status of recovery efforts taking place across a range of dryland ecosystems, emphasize advances in the region-specific understanding of plant community development, and (2) provide comparisons between the primary drivers and limitations to restoration that exist across dryland systems. [ABSTRACT FROM AUTHOR]

In a companion paper, the agricultural drought economic risk assessment (ADERA) model was described. ADERA studies agricultural drought not only in terms of deficit soil water content and its frequency and severity (as in the traditional approach) but also in terms of net benefit reduction and vulnerability. The relationship between drought index, crop yield, and crop economic net benefit is modeled and three threshold levels are considered: the critical water content; the critical impact in terms of net benefit; and its critical return period (i.e., frequency) above which the soil-climate unit is considered unsuitable for the cultivation of a specific crop. These critical levels are used in long-term action planning as the triggers for different risk classes. The rapidity with which the critical impact is reached is considered indicative of the crop vulnerability, and real-time monitoring of the impact evolution (short-term actions) is also implemented. Initially ADERA was applied at only one point (soil-crop-climate unit), but because agricultural drought is by definition a wide area phenomenon, the model must be validated in other units and then used to evaluate the drought area extension (risk map). In this paper, generalization, demonstration, and guidance on the application of ADERA are given with reference to rainfed sunflower and sorghum crops in six soil-climate units in central Italy for which time series for yield (obtained in experimental plots where the water scarcity was the principal factor limiting the final yield) since 1978 is available. The application of ADERA made it possible to quantify the vulnerability class and the corresponding risk class for the single unit (long-term action planning). The analysis results confirm that typically for the selected crops the critical impact has a low risk and a low vulnerability. In fact sunflower and sorghum are rainfed crops widely cultivated in the area under investigation. Moreover, the results show that each risk class is present only within a specific cost range, in particular the upper and lower limits, and the size of each cost range varies according to the different units; the occurrence of a specific risk class and vulnerability level is highly correlated with the selected triggers, in particular with the critical net benefit (for an increment of which above the corresponding cost range, a given soil-climate unit can become unsuitable for the cultivation of a specific crop); the critical water content is a normal occurrence event for all the units analyzed, with the crop water stress onset date always around 40% of the growing period being a typical characteristic of the specific area, of the two crops and of the selected drought index. The practical usefulness of the impact monitoring procedure was stressed by comparing its progressive evolution in the cases of both a rainfed crop and of a rescue irrigation carried out at a selected and opportune date. In the latter case the impact was reduced below the critical level. [ABSTRACT FROM AUTHOR]

In this paper, unconfined porous medium is considered to drain vertically to an underlying fractured aquifer, which leads groundwater to a variable large diameter well blind to porous medium. Such cases are quite common in arid regions, where the geological layers have top to bottom sequence as quaternary sedimentary layer (porous-unconfined aquifer), weathered and/or fractured underlying layers (fractured-confined aquifer), which are underlain by impervious rock formation. The necessary type curves are provided both for the fractured (pumped) and overlying porous (unpumped) media. Initially, the effect of varying well diameter on the drawdown is explained. The general groundwater movement equation for this configuration yields to well known Theis, Hantush, and Jacob solutions. It is also indicated that at large times, classical Jacob straight line is not valid in every case, because there is a set of other straight lines with different slopes. The application of the methodology is presented for an aquifer test in the Kingdom of Saudi Arabia. [ABSTRACT FROM AUTHOR]

Introduction Analysis of the spatial and temporal trends of precipitation is pertinent for the future sustainable management of water resources. Urbanization and climate change affected local rainfall and intensity. As rainfall characteristics are often used to design urban drainage systems, so watershed modeling, and estimate of the flood properties, updating and reviewing rainfall characteristics is necessary. The Intensity-Duration-Frequency (IDF) curves are a suitable tool to estimate the threshold values of precipitation in different return periods. IDF curves should be prepared based on the long-term rainfall statistics in each region and can change under the influence of climate change. These curves which indicate the frequency and maximum intensity of annual rainfall in the different return periods are suitable tools for planning and managing the water resources. IDF curves are broadly used for different purposes, such as the design of flood control and diversion structures in the cities. The main purpose of this research is to investigate the effect of climate change on temperature, precipitation, and IDF curves in the different return periods in an arid environment. Materials and Methods In this research, the effect of climate change on IDF curves was investigated in Kashan City as a dry region. Kashan city with an area of 9647 km2 is located in the northern part of the Isfahan Province. In this study, RCP8.5, RCP4.5, and RCP2.6 scenarios (which are introduced as optimistic, intermediate, and pessimistic scenarios) reported in the fifth assessment report of the Intergovernmental Panel on Climate Change (IPCC), were used to predict the impacts of climate change on temperature and precipitation changes. Then, IDF curves were calculated evaluated, and compared for the basic (1993-2017) and future periods (2011-2070). To examine the impact of climate change on the rainfall intensity patterns, it is necessary to extract IDF curves in different climate conditions. Bell's method is a usual method for extraction of the IDF curves, which was promoted by Gharehman-Abkhezr in Iran. In this study, the latest promoted relationships developed were for the desert and southern regions (e.g;Nizar-Salfachgan, Kuhpayeh, Herat, and Jiroft basins in the central Provinces, Qom, Isfahan, Kerman, and Yazd) have been presented and used to extract IDF curves. To investigate the effects of climate change on IDF curves, first, the base period curves were extracted via rainfall data measured at the Kashan synoptic station. Then, using the new climate scenarios (RCP8.5, RCP4.5, and RCP2.6) and the output data of the LARS exponential microscale model, the IDF curves were extracted for different climate scenarios in the future (2011-2030), (2031-2050), and (2051-2070). Finally, the results of these curves were compared with the base period. Results and Discussion According to the results, for the base period, the precipitation and temperature data were predicated with an acceptable accuracy by the LARS model. The accuracy of the model has been higher in estimating the minimum and maximum temperature. the Nash and explanation coefficients for the maximum and minimum temperatures were 0.99 and 0.99, respectively. While, the explanatory and Nash coefficients for precipitation data were 0.95 and 0.93, respectively. Based on the results, the rainfall intensity will have fewer changes compared to the base period for long-term duration rainfall compared to short-duration rainfall (less than four hr. The maximum changes are related to rainfalls with a duration of less than one hour, whereas the minimum changes are predicted for 24- hr rainfalls. For all studied scenarios, a significant difference (P<0.05) was predicted between the average rainfall intensity of 0.17 to 24 hr in the region. As in the two-year return period and under the 2.6 scenario, rainfall intensity was increased from 10.75 to 30.54 mm hr-1 for the duration time of 0.17 hr. Conclusion An increase in air temperature, decrease in rainfall, change in the rainfall pattern, decrease in river discharge, and increase in sudden floods, followed by an increase in soil erosion, and a decrease in the amount of agricultural products are the results of climate change. Therefore, the long-term analysis and monitoring of climatic conditions can be very effective for crisis management caused by climate changes such as floods and droughts. Based on the results, the effect of climate change on the intensity of short-term rainfall is greater than long-term duration rainfall, as the intensity of short-term rainfall will increase more than long-term rainfalls. [ABSTRACT FROM AUTHOR]

Wheat is one of the most important cereal crops in Egypt and all over the world. Its productivity is adversely affected by drought due to deficient irrigation to provide nutrients required for plant growth. In a field experiment, silicon foliar applications at concentrations of 0, 200, and 400 mg L−1 were performed at different irrigation rates ranging from 1000 to 4000 m3 ha−1 to assess water irrigation productivity and wheat crop yield in a calcareous soil under arid climate conditions. Increased irrigation rates led to a significant increase in soil nutrient dynamics, as well as in the number and weight of grains per spike, leaf area index, grain yield, straw yield, and biological yield, with the exception of the weight of 1000 grains. Spraying with sodium silicate had a significant impact on grain yield and harvest index but did not significantly impact the other traits. Furthermore, the interaction between irrigation and silicate application rates showed significance only for grain yield, the number of spikes/m2, and the harvest index. Applying three times irrigation could produce the highest nutrient retention, wheat yield, and water irrigation productivity. No significance was observed between 3000 m3 ha−1 and 4000 m3 ha−1 irrigation, indicating a saving of 25% of applied irrigation water. It can be concluded that applying irrigation at 3000 m3 ha−1 could be a supplemental irrigation strategy. High wheat grain yield can be achieved under deficit irrigation (3000 m3 ha−1) on the northwestern coast of Egypt with an arid climate by spraying crops with sodium silicate at a rate of 400 mg L−1. [ABSTRACT FROM AUTHOR]

Orenburg Region is located in the South Urals, mostly in the steppe zone and is characterised by various landscapes suitable for many Chenopodiaceae. The species of Chenopodiaceae are present in all major plant communities (saline vegetation, steppes, on limestone, chalk and sand, and as degraded or ruderal communities). In the steppe zone, many native subshrubby species (Atriplex cana, Caroxylon laricinum, Suaeda physophora) playing a crucial role in semi-deserts (known as southern steppes in the recent Russian literature) located southwards of Orenburg Region are locally found, and several annuals (Salicornia perennans, Suaeda spp.) are most common dominants in plant communities. Some typical semi-desert species (Kalidium foliatum, Bassia hyssopifolia, Soda foliosa, Spirobassia hirsuta) are found in the easternmost part of the region.We compiled a checklist of Chenopodiaceae in Orenburg Region, with two new records (Chenopodium virgatum, Corispermum laxiflorum), based on our critical revision, comprehensive inventory of herbarium specimens and documented observations and field research. In total, we report 76 species in the Region, which is the third-highest number of the Chenopodiaceae species compared with other administrative territories of European Russia, North Caucasus and West Siberia. Alien and native taxa are distinguished. Zonal patterns of species distributions are confirmed. A preliminary conservation status is proposed for each native species. Three species are recommended for exclusion from the Red Data Book of Orenburg Region: Petrosimonia triandra (because of its extensive distribution), Kalidium foliatum and Anabasis salsa (because of the lack of actual threat to their populations). Arthrophytum lehmannianum and Salsola rosacea are considered threatened (Vulnerable) because of their restricted occurrence and population size and because their localities are under anthropogenic pressure. Atriplex hortensis, Atriplex rosea, Chenopodium acuminatum, C. karoi, C. praetericola, C. vulvaria, Climacoptera affinis, C. crassa, Halimocnemis karelinii, Salsola paulsenii and Xylosalsola arbuscula are excluded from the checklist, based on various reasons as discussed in the paper. Point distribution maps are provided for each species. Agriophyllum pungens (Vahl) Link is accepted as the correct authorship instead of "M.Bieb. ex C.A.Mey."

Abstract Given the aesthetic, cultural, ecological, and economic value of the date agro-system in Southwestern Tunisia, different management and conservation strategies have been warrantee to optimize land productivity sustainably. However, the inefficiency of the adopted management actions resulted in a continuous loss of soil fertility and decreasing fruit quality. Thus, the present paper attempts to evaluate accurately the evolution of the principal factors influencing date palm production and agricultural activities sustainability in the region. Integrated approaches of various irrigation water quality indices and geostatistical analysis coupled with field investigation and farming survey were applied to evaluate the evolution of key parameters influencing the development of date palm sustainably. The obtained results of the research indicate that the progressive land degradation is due to the effects of poorquality of water used for irrigation (EC between 674.4 and 5450 µs/cm, SAR exceeding locally 20 and about 80% of all the samples waters are of undoubtful quality according to the calculated indices), inappropriate irrigation scheduling (physiologic drought that might reach 3 months), traditional basin irrigation technique (decreasing of yield productivity, locally of 0.23, 0.23 and 0.25 kg m−3), an indigenous knowledge (sandy amendment, biologic compost, gravity improved irrigation…..). Also climate variability has leaded to furthermore degradation of crop quality. The degradation of date palm culture will be a great challenge for environmental conservation, food security and socio-economic values of the region unless a reasonable management take place, a flexible strategy based on indigenous knowledge of landowner, and scientific-based outlines with climate risks evaluation. The present paper might be useful to policy makers as a multi-disciplinary research covering most of the important aspects of date palm production.

In this paper we argue that historians of the eastern Arab lands (Ar. at-mashriq al-'arabi) should turn their attention to the Bedouins for two main reasons. First, the societies in the Arab East cannot be adequately understood without a full evaluation of their Bedouin component, especially outside urban areas. Second, studying the Bedouins can open new perspectives on important debates in Middle Eastern historiography. The paper further contends that the arid lands of the Arab East still need to be explored as a historical region with its own distinct patterns of regional connectivity and political organisation. Finally, we highlight environmental history and the study of emic categories as promising avenues for future research on this region. [ABSTRACT FROM AUTHOR]

Addressing land subsidence requires the identification of root causes, modeling its initiation failure modes, and managing this risk in a cost-effective manner. This paper presents a methodology for quantifying and managing the risk of land subsidence resulting from underground cavities and illustrates this methodology using a case study of a site that was exposed to such a phenomenon in Kuwait. The methodology produces the hazard and risk profiles by computing the probability of sinkhole formation over a selected geographic area based on field data and examining spatial characteristics of the cavities. Developing the methodology required reviewing project plans and relevant reports, defining decision processes relating to land subsidence resulting from underground cavities, examining the spatial characteristics of cavities, performing reliability analysis for a selected failure mode, and performing regression analysis for predicting grout volume needed to fill in cavities. Considering for illustration purposes one of the failure modes without the important effects of the water table resulted in a very small failure probability. Future studies should take into consideration the development of performance functions and limit states for other failure modes, including the effects of the water table. The spatial analysis of cavities confirmed their random layout without any spatial trends or characteristics. A regression model for predicting grout volume as a function of cavity height was developed with statistically significant regression coefficients, a small correlation coefficient, and a low reliability level for prediction. [ABSTRACT FROM AUTHOR]

Abstract: Ephemeral and intermittent streams are abundant in the arid and semiarid landscapes of the Western and Southwestern United States (U.S.). Connectivity of ephemeral and intermittent streams to the relatively few perennial reaches through runoff is a major driver of the ecohydrology of the region. These streams supply water, sediment, nutrients, and biota to downstream reaches and rivers. In addition, they provide runoff to recharge alluvial and regional groundwater aquifers that support baseflow in perennial mainstem stream reaches over extended periods when little or no precipitation occurs. Episodic runoff, as well as groundwater inflow to surface water in streams support limited naturally occurring riparian communities. This paper provides an overview and comprehensive examination of factors affecting the hydrologic, chemical, and ecological connectivity of ephemeral and intermittent streams on perennial or intermittent rivers in the arid and semiarid Southwestern U.S. Connectivity as influenced and moderated through the physical landscape, climate, and human impacts to downstream waters or rivers is presented first at the broader Southwestern scale, and secondly drawing on a specific and more detailed example of the San Pedro Basin due to its history of extensive observations and research in the basin. A wide array of evidence clearly illustrates hydrologic, chemical, and ecological connectivity of ephemeral and intermittent streams throughout stream networks. [ABSTRACT FROM AUTHOR]

Lake Urmia, in northwest Iran, is the second most saline lake in the world. During the past two decades, the level of water has markedly decreased. In this paper, climate of the lake region is investigated by using data from four meteorological stations near the lake. The data include climatic parameters such as temperature, precipitation, humidity, wind speed, sunshine hours, number of rain days, and evaporation. Climate around the lake is examined by way of climate classification in the periods before and after the reduction in water level. Rainfall in the lake catchment is also evaluated using both gauge and satellite data. The results show a significant decreasing trend in mean annual precipitation and wind speed and an increasing trend in annual average temperature and sunshine hours at the four stations. Precipitation and wind speed have decreased by 37 mm and 2.7 m/s, respectively, and the mean annual temperature and sunshine hours have increased by 1.4 °C and 41.6 days, respectively, over these six decades. Only the climate of the Tabriz region is seen to have significantly changed, going from semiarid to arid. Gauge records and satellite data show a large-scale decreasing trend in rainfall since 1995. The correlation between rainfall and year-to-year changes in lake level is 0.69 over the period 1965 to 2010. The relationship is particularly strong from the early 1990s to 2005. This suggests that precipitation has played an important role in the documented decline of the lake. [ABSTRACT FROM AUTHOR]

The county (city) located on the northern slope of the Kunlun Mountains is the primary area to solidify and extend the success of Xinjiang Uygur Autonomous Region, China in poverty alleviation. Its Sustainable Development Goals (SDGs) are intertwined with the concerted economic and social development of Xinjiang and the objective of achieving shared prosperity within the region. This study established a sustainable development evaluation framework by selecting 15 SDGs and 20 secondary indicators from the United Nations' SDGs. The aim of this study is to quantitatively assess the progress of SDGs at the county (city) level on the northern slope of the Kunlun Mountains. The results indicate that there are substantial variations in the scores of SDGs among the nine counties and one city located on the northern slope of the Kunlun Mountains. Notable high scores of SDGs are observed in the central and eastern regions, whereas lower scores are prevalent in the western areas. The scores of SDGs, in descending order, are as follows: 62.22 for Minfeng County, 54.22 for Hotan City, 50.21 for Qiemo County, 42.54 for Moyu County, 41.56 for Ruoqiang County, 41.39 for Qira County, 39.86 for Lop County, 38.25 for Yutian County, 38.10 for Pishan County, and 36.87 for Hotan County. The performances of SDGs reveal that Hotan City, Lop County, Minfeng County, and Ruoqiang County have significant sustainable development capacity because they have three or more SDGs ranked as green color. However, Hotan County, Moyu County, Qira County, and Yutian County show the poorest performance, as they lack SDGs with green color. It is important to establish and enhance mechanisms that can ensure sustained income growth among poverty alleviation beneficiaries, sustained improvement in the capacity of rural governance, and the gradual improvement of social security system. These measures will facilitate the effective implementation of SDGs. Finally, this study offers a valuable support for governmental authorities and relevant departments in their decision-making processes. In addition, these results hold significant reference value for assessing SDGs at the county (city) level, particularly in areas characterized by low levels of economic development. [ABSTRACT FROM AUTHOR]

Climate change impact reports by the Intergovernmental Panel on Climate Change (IPCC) are well established throughout the world. By now many local, regional, and central authorities are aware of these impacts and they try to take necessary precautions according to their environmental circumstances. Preliminary decisions cannot be taken unless there is a model for future climate change impacts, especially for rainfall occurrence, amount, and frequency estimations. The main purpose is to combine the general circulation (climate) model (GCM) outputs with the local meteorology station records by a suitable downscaling procedure. In this paper, a statistical quadrangle downscaling model (QDM) is developed for rainfall estimations up to 2100. This model helps to downscale the nearby four scenario rainfall amounts at GCM grids to a desired point. Two main steps in the model structure are the use of a regional dependence function (RDF) for transferring the GCM output data from the four nearest grid points to the location. The second step is to adjust the downscaled scenario monthly rainfalls with the local rainfall records. The GCM monthly rainfall outputs are downloaded from the National Center for Atmospheric Research (NCAR) with special report emission scenario A2. The application of the methodology is presented for Riyadh City, Kingdom of Saudi Arabia (KSA). The RDF is obtained from the most reliable meteorology records at 27 locations that are irregularly scattered all over the country. Then it is used for scenario data transfer from the regular grid points. The adjustment is based on the average statistical properties of concurrent monthly rainfall amounts between 1985 and 1996. The trend component in the GCM remains intact. It has been observed that there is a major increasing trend in the monthly rainfalls after 2050. In the meantime, each decade starting from 2011 gives estimates that indicate steady rainfall increases up to 2050. The QDM indicates a 40% increase in the annual total rainfall amounts, with a 15% standard deviation increase. [ABSTRACT FROM AUTHOR]

The paper proposes a new methodology that studies agricultural drought not only in terms of deficit soil water content, its frequency and severity, as in the traditional approach, but also in terms of net benefit. For this purpose the relationship between drought index, crop yield, and crop economic net benefit is modeled and three threshold levels are considered. The first is the critical water content, below which the crop faces water stress (termed as potential agricultural drought). The second is the critical net benefit, below which there is meager (e.g., zero) profit (termed as actual agricultural drought). The third is the critical return period (or frequency) of the actual agricultural drought, below which there is an agricultural aridity (almost steady phenomenon with high impact, high risk) and above which there is an agricultural drought (occasional phenomenon with high impact, low risk). To pinpoint the time of occurrence of the potential and the actual agricultural drought, real-time monitoring is conducted. The rapidity with which these critical conditions are reached is considered as indicative of the crop vulnerability to the corresponding phenomenon. The evolved methodology therefore is based on an objective definition of agricultural drought and is formulated accounting for its peculiar characteristics. The methodology is called the risk analysis and economic impact assessment of agricultural drought (ADERA). ADERA is applied to the rainfed sunflower crop in the Papiano (central Italy) experimental plots for which the 26-year time series for yield and the corresponding phenological, climatic, and economic data are available. The drought index-crop yield-crop economic net benefit relationship makes it possible to quantify the frequency (return period) of the actual agricultural drought and to show that for the given costs and crop sale price the actual agricultural drought risk for the crop is low. For the case study, the vulnerability of the unit to the agricultural drought is low, as the critical net benefit typically occurs late in the growing season. [ABSTRACT FROM AUTHOR]

This paper presents the area and water allocation model (AWAM), which incorporates deficit irrigation for optimizing the use of water for irrigation. This model was developed for surface irrigation schemes in semiarid regions under rotational water supply. It allocates the land area and water optimally to the different crops grown in different types of soils up to the tertiary level or allocation unit. The model has four phases. In the first phase, all the possible irrigation strategies are generated for each crop-soil-region combination. The second phase prepares the irrigation program for each strategy, taking into account the response of the crop to the water deficit. The third phase selects the optimal and efficient irrigation programs. In the fourth phase of the model, irrigation programs are modified by incorporating the conveyance and the distribution efficiencies. These irrigation programs are then used for allocating the land and water resources and preparing the water release schedule for the canal network. [ABSTRACT FROM AUTHOR]

In this work, applications of the coupled solid set sprinkler irrigation and crop model AdorSim introduced in the companion paper are presented. The sprinkler irrigation model is based on ballistic theory, while the crop model is based on CropWat. AdorSim was used to evaluate the effect of sprinkler spacing on seasonal irrigation water use (WU) and crop yield. The most relevant results were related to the characterization of advanced irrigation scheduling strategies. The differences in crop yield and WU derived from irrigating at different times of the day were estimated for two locations strongly differing in wind speed. Irrigation guidelines were established in these locations to relate gross water use and water stress induced yield reductions. Simulations were also applied to estimate adequate wind speed thresholds for irrigation operation. In the experimental conditions, thresholds of 2.0–2.5 m s-1 proved effective to control yield reductions and to minimize WU. [ABSTRACT FROM AUTHOR]

Beginning in the early twentieth century and progressing rapidly since the 1950s, large-scale water works have created engineered rivers. In dry-land basins they control flooding and provide water and energy to farms, cities and industry. Yet, they face numerous challenges. In 2013 we formed an interdisciplinary team to study future conditions of nine river basins worldwide. This paper presents the methodology and interim results for two of our basins, the Rio Grande and the Euphrates-Tigris. We conclude with a new definition of the sustainability of engineered rivers in arid lands, using dependable reservoir yield under drought conditions as the central indicator. [ABSTRACT FROM PUBLISHER]

This paper analyzes the relationship between virtual water and domestic food-water security in Qatar. The total virtual water traded between 1998 and 2015 was 24,470 Mm3, average of 1,360 Mm3y–1. Green water and blue water account 69 and 31% of total virtual water import. On average, 70% of the total water requirement is from virtual water import and Qatar’s dependence on virtual water for agricultural products increased to 90% in 2015. The paper examines the virtual water flow from the major river basins in India, Pakistan, Australia and groundwater aquifers in Saudi Arabia and policy implications of virtual water on food security of Qatar. [ABSTRACT FROM AUTHOR]

In December 2018, the University of Arizona was awarded a US$3.9 million contract from the Sultanate of Oman to develop research laboratories for the country's "One Million Date Palms for Oman" initiative. This project is only the most recent example of a much longer set of collaborations between actors in the two regions, which began when Omani date palms were imported to the University of Arizona's Agriculture Experiment Station in the 1890s. In tracing this history, I show how establishing state power in the US West was facilitated by the work of scientists and research institutions drawing on materials and knowledge from the Middle East. In the case of Arizona, the colonial project was advanced through the federally funded land‐grant programmes at the University of Arizona, which aimed to entice white settlers to the territory through promoting commercially oriented agriculture. University researchers' efforts to secure date palm imports from abroad illustrate how the settler colonial vision treated the desert Southwest as an analogue to the Middle East, but their personal laboratory for developing modern knowledge about desert farming. The case sheds light on the role of scientific institutions in consolidating state power in desert frontiers – a process that is depoliticised by framing the desert as a laboratory as a site for "modern" science rather than a site to be colonised. [ABSTRACT FROM AUTHOR]

Background and aims -- Endemism may be defined according to the time of origin of taxa. Neo-endemics refer to relatively recent species that have not dispersed outside their ancestral areas. In contrast, paleo-endemics refer to species of ancient origins, which are currently geographically restricted but probably were more widespread in the past. Geographically, endemism areas may also be based on the co-occurrence of more than one species. We aimed to qualitatively identify the neo-endemism and paleo-endemism of endemic Cactaceae of the Tehuacán-Cuicatlán Valley, as well as to quantitatively assess paleo- and neo-endemics areas. Material and methods -- Using a dated molecular phylogeny of endemic Cactaceae, we defined paleo- and neo-endemics using an arbitrary boundary of 2.6 million years ago; we also assessed the significance of concentrations of these species using a categorical analysis of paleo- and neo-endemism. Key results -- Our results showed that most endemic Cactaceae in the Tehuacán-Cuicatlán Valley arose throughout the Pleistocene, while categorical analysis indicated localised mixed- and super-endemism (including both paleo- and neoendemics) areas. Conclusion -- We suggest that paleo- and neo-endemics, as well as localised mixed-endemism areas, may have originated due to a probable high climatic stability in the Tehuacán-Cuicatlán Valley, which in addition to topographically rugged and ecologically complex zones (e.g. ecotones, isolated habitat patches) may have allowed it to function as a refuge throughout Pleistocene climatic changes, mainly promoting the speciation of neo-endemics, as well as the persistence of relatively few paleo-endemics. [ABSTRACT FROM AUTHOR]

The agricultural and environmental functionality of irrigation districts is sometimes controversial, with salinity as a frequent argument in the arid countries. In the 20th century, the Spanish Ministry of Agriculture studied the degree and extent of salinity and other facets of irrigated districts in Spain by conducting soil surveys and land evaluations from the 1940s to the early 1980s. This article presents a--probably partial--list and the available details of these studies for the Ebro Basin. We had access to some of these studies, although for most of them we only have indirect information; we also indicate the existence of these kinds of studies for other regions of mainland Spain. However, updated systematic estimations of the extent and degree of soil salinity are unavailable for most of the irrigated lands in Spain and for many other dry countries. A feasible task, as shown further in the article, is screening the value of the still readable studies and selecting the irrigation districts whose past documentation and present status allow for a new evaluation of soils, or at least measuring their actual salinity for comparison with the previous data. The results will help irrigators, government agencies, and other stakeholders in the appraisal of the effects of agricultural practices--chiefly the application of water--and to re-design them if needed. We advocate for the collection and critical review of the surviving soil studies, and for their rescue through scanning and digitalization. This task is compelling due to the decay of the existing paper documents. [ABSTRACT FROM AUTHOR]

"Dry Matters" describes a dual interest. The phrase reminds designers that drylands are active contributors to our collective futures and advocates for an expanded material palette to design resilient arid landscapes. It is also the conceptual framework of a graduate design studio that I teach at the University of California, Berkeley which is predicated on the assumption that aridity is an intrinsically valuable ecological condition. In this essay, I recount how dryland policies, attitudes, and perceptions manifest materially through design and planning. Grounding this research, I show how engaging the history of place can be a pedagogical framework for students to design speculative dryland futures. [ABSTRACT FROM AUTHOR]

Abstract: The delta of the Colorado River in Mexico supports about a million hectares of riparian, marsh and estuarine habitats of international importance. Some of these habitats depend on flows of fresh and brackish water from the U.S. and Mexico. Up to now, these flows were the incidental result of water management actions taken to provide water for agriculture and municipal use, protect against flooding, and dispose of saline agricultural return flows. This paper briefly describes the wetlands and documents recent bi-national efforts to provide environmental flows to the delta, codified in Minutes 306, 316 and 319 of the water treaty between the U.S. and Mexico for the utilization of Colorado River water. Providing water for environmental uses in this watershed will be a daunting task given the many competing uses for water and expected diminished flows due to climate change. The paper serves as an introduction to a special issue of Ecological Engineering, Wetlands of the Colorado River Delta, which contributes 17 new research articles to the science based on these diverse aquatic habitats. We hope these studies will be useful to those developing management strategies to preserve and enhance these habitats for the future. [Copyright &y& Elsevier]

Monitoring soil salinization has been a difficult process in arid lands due their large spatial and temporal variability. Hyperspectral remote sensing has offered a potential for faster detection of salinization process but mostly from empirical approaches. In this paper, an integrated approach combining model inversion and empirical regressions has been proposed for soil salt content (SSC) estimation from hyperspectral information obtained from controlled laboratory experiments. All soil samples were artificially salinized using \Na2\SO4, NaCl, and \Na2 \CO3 (99% purity) salts to different levels and to different soil-moisture conditions, since soil moisture often jointly affects reflectance spectra with SSC. Hapke model was calibrated and validated for its simulation on soil reflectance and showed good agreements with measured data. The optimal values of single scattering albedo that was inversely retrieved from the Hapke model had good relationships with SSC at 2000–2200 nm for each treatment even under various soil-moisture conditions. Taking usage of these findings, the integrated approach obtained high accuracies on SSC estimations with R^2's of 0.90, 0.86, and 0.72 and slightly dropped R^2's of 0.89, 0.81, and 0.67 for NaCl-, \Na2\SO4-, and \Na2\CO3-type saline soils under respective dry and wet conditions. The R^2 decreased to 0.55 and 0.53 for dry and wet soils when salt types were ignored. The integrated approach provides a novel as well as an efficient way for SSC estimation from reflected spectra, and hence, we foresee its potential applications for large-scale SSC mapping from reflectance measurements. [ABSTRACT FROM PUBLISHER]

The Limarí River basin is one of the most important watersheds in north-central Chile (30°S). Its headwaters lie at the top of the subtropical Andes ( above sea level) and the river flows westward into the Pacific Ocean over a length of approximately 200 km. This basin has a marked snowmelt-driven hydrological regime and, in spite of the arid conditions that characterize this region, holds more than 50,000 ha of highly productive agricultural land thanks to its irrigation infrastructure and three interconnected reservoirs. Like many semiarid regions around the world, north-central Chile is expected to become warmer and drier during the 21st century as a consequence of ongoing anthropogenic climate change. The associated reduction in streamflow, changes in hydrograph timing, and enhanced evapotranspiration will undoubtedly threaten agriculture in the Limarí basin and elsewhere in semiarid Chile. In this paper, the effect of temperature and precipitation on surface hydrology, performance of water infrastructure, and irrigation coverage in the Limarí basin is investigated by using the water evaluation and planning (WEAP) model. WEAP was calibrated by using current climate and agriculture patterns, and then forced with a set of 30-year-long climate scenarios, each of them obtained by adding a temperature and precipitation perturbation to the historical time series. This delta approach allows (1) determination of the sensitivity of selected variables to climate change, and (2) obtaining a projection of the effects in irrigation coverage expected for the near and far future (2010-2040 and 2070-2100, respectively). Both aspects are investigated for agricultural districts with varying access to irrigation infrastructure and groundwater; this exercise highlights the relevance of added storage and innovative conjunctive use of surface and groundwater resources for improving the resilience and adaptability of irrigated agriculture in the face of a changing climate. [ABSTRACT FROM AUTHOR]

Net radiation (Rn) is the main driving force of evapotranspiration (ET) and is a key input variable to the Penman-type combination and energy balance equations. However, Rn is not commonly measured. This paper analyzes the impact of 19 net radiation models that differ in model structure and intricacy on estimated grass and alfalfa-reference ET (ETo and ETr, respectively) and investigates how climate, season and cloud cover influence the impact of the Rn models on ETo and ETr. Datasets from two locations (Clay Center, Nebraska, subhumid; and Davis, California, a Mediterranean-type semiarid climate) were used. Rn values computed from the 19 models were used in the standardized ASCE-EWRI Penman-Monteith equation to estimate ETo and ETr on a daily time step. The influence of seasons on the estimation of Rn and on estimated ETo and ETr was investigated in winter (November-March) and summer (May-September) months. To analyze the influence of clouds on the impact of Rn models, relative shortwave radiation (Rrs) was used as a means to express the cloudiness of the days as: 0≤Rrs≤0.35 for completely cloudy days; 0.35rs≤0.70 for partially cloudy days; and 0.70rs≤1.0 for clear sky days. The performances of Rn models showed variations at the same location and between the locations for the same model based on methods used to calculate various model parameters. The most significant impact of Rn on estimated ETo and ETr was related to the methods used to calculate atmospheric emissivity ([variant_greek_epsilon]) rather than methods used to calculate clear sky solar radiation (Rso) or cloud adjustment factor (f). Rn models that used average air temperature to compute [variant_greek_epsilon] and an estimated f resulted in good performances at both locations. Empirical models that assumed f=1.0 showed poor to average performances at both locations. While model performances varied based on methods used to calculate Rso, f, and [variant_greek_epsilon], there were significant seasonal variations in performances of models that calculated [variant_greek_epsilon] as a function of actual vapor pressure of the air (ea). The seasonal variations in performances of these models were greater under subhumid climate at Clay Center than in semiarid climate at Davis, Calif. The models that calculated [variant_greek_epsilon] as a function of ea performed better under completely cloudy days than on other days, more so at Clay Center. Methods used to calculate [variant_greek_epsilon] have a significant impact on the Rn model performance, especially in unstable climatic conditions such as at Clay Center where there are frequent and rapid changes in climatic variables in a given day and throughout the year. The results of this study can be used as a reference tool to provide practical information on which method to select based on the data availability for reliable estimates of daily Rn relative to the ASCE-EWRI Rn method in subhumid and semiarid climates similar to Clay Center, Neb. and Davis, Calif. [ABSTRACT FROM AUTHOR]

Arid lands are in the need of additional water supply but water transportation from outside of the natural hydrological cycle causes the groundwater to rise within the urban areas. Additional water supply from surrounding areas or through the desalination plants provides comfort in domestic activities but after the usage, its disposition is necessary in an efficient manner. Unfortunately, arid region cities have neither sufficient nor efficient sewage system. Consequently, the water returned to surface cesspools and leakages from insufficient sewage system makes internal groundwater recharge within the urban area. Additionally, water supply system leakages further raise the groundwater level. Deterioration in water quality becomes a potential danger for the infrastructure and foundations. Surface depressions in the city may be flooded due to groundwater level rise and at times bed smells occur at various parts of the city. In this paper, a quantitative method is followed to assess groundwater level rise risks in addition to the few chemical risks associated with sulfate and chloride solids. It is observed that each one of these variables has different probability distribution function and expose risk maps with different features. [ABSTRACT FROM AUTHOR]

In the arid regions of Tunisia, considerable investments are being made to maintain the old water harvesting techniques and introduce new ones to capture the scarce amount of rainwater (100 mm to 230 mm annually) for agricultural and domestic purposes. However, no detailed assessment of the multiple effects and the costs and benefits of these techniques have been made so far. This paper summarizes the results of an in depth investigation of the multiple impacts (runoff mobilization, ground water recharge, agro-socio-economic impacts) of the water harvesting works undertaken in the watershed of oued Oum Zessar (southeastern Tunisia). The importance of interdisciplinary and integrated approaches was revealed through this detailed impact assessment and economic evaluation. In fact, the profitability of the water harvesting works depends largely on the criteria chosen. However, further refinements are needed to better include all possible impacts (positive and negative) that occur as a result of the installation of the water harvesting structures. [ABSTRACT FROM AUTHOR]

This paper examines the mid- to late-Holocene (c. 6850-1160 cal. yr BP) environmental history of Sierra de Gádor in southern Spain. The local vegetation dynamics are reconstructed through the palaeoecological record obtained from a lacustrine deposit situated at 1530 m. Various hypotheses are considered to explain the vegetation dynamics apparent in the palaeoecological evidence, including climatic change, fire occurrence and human activity. Although the vegetation in this region is sensitive to climatic change, threshold events driven by ecological factors are also apparent. Climatic events include a thermo-mesophytic optimum with abundance of deciduous trees and maximum lake water level found from c. 6850 to 5500 cal. yr BP. In contrast, changes in the frequency of major fire episodes appear to have shaped interspecific relationships and vegetation change, especially from c. 4200 cal. yr BP onwards. Biotic properties of the ecosystem such as the inertia of established tree populations, interconnected with competition adjustments, appear also to have played a role. Over the last two millennia, overgrazing, combined with natural and/or human-set fires, appears to have pushed mountain forests over a threshold leading to the spread of grassland, thorny scrub, junipers and nitrophilous communities. [ABSTRACT FROM AUTHOR]

The last decade has seen spirited debates about how resource availability affect the intensity of competition. This paper examines the effect that a dominant introduced species, Carrichtera annua, has upon the winter annual community in the arid chenopod shrublands of South Australia. Manipulative field experiments were conducted to assess plant community response to changing below-ground resource levels and to the manipulation of the density of C. annua. Changes in the density of C. annua had little effect on the abundance of all other species in the guild. Nutrient addition produced an increase in the biomass of the most abundant native species, Crassula colorata. An analysis of the root distribution of the main species suggested that the areas of soil resource capture of C. annua and C. colorata are largely segregated. Our results suggest that intraspecific competition may be stronger than interspecific competition, controlling the species responses to increased resource availability. The results are consistent with a two-phase resource dynamics systems, with pulses of high resource availability triggering growth, followed by pulses of stress. Smaller plants were nutrient limited under natural field conditions, suggesting that stress experienced during long interpulse phases may override competitive effects after short pulse phases. The observed differences in root system structure will determine when plants of a different species are experiencing a pulse or an interpulse phase. We suggest that the limitations to plant recruitment and growth are the product of a complex interplay between the length and intensity of the pulse of resource availability, the duration and severity of the interpulse periods, and biological characters of the species. [ABSTRACT FROM AUTHOR]

With their modest rainfall, arid regions are characterized by relatively fewer species than the better-watered biomes. But this makes it all the more important that the biodiversity that is present in arid environments be given even higher priority; for each species lost from an arid region, the percentage of loss for the region''s biodiversity is much higher than in more species-rich regions. And some species, such as bees and ants, are particularly diverse in arid habitats. Realizing the importance of biodiversity in the arid regions where they live, local people have devised numerous ways of limiting their impact. Historically, such regions have been especially subject to changes in climate, which affect productivity; these changes have often been accompanied by conflicts. The paper will describe these from various parts of the arid world, as a basis for comparison. The paper will also examine economic issues relating to biodiversity in arid lands, focusing especially on the relationship between biodiversity and various kinds of development projects. The major challenges in implementing the Convention on Biological Diversity (CBD) in arid lands lie not so much in the biology of the species concerned, but rather in the social, economic, and political arenas within which people operate. We need to build a broader constituency for conserving biodiversity, extend the responsibility for conserving biodiversity far beyond government, bring local people into the conservation movement, ensure that sufficient information is available to those who need it, restore degraded ecosystems, and stimulate far greater public support for biodiversity. [Copyright &y& Elsevier]

Mammals have been widely recognized as mobile link species that can vectorize resources across the landscape. In this study, we analyze the biodeposition of waste products egested by native herbivorous mammals of the Monte Desert to document for the first time the implications of the restoration of a native forest on this process. We compared a restored native woodland an adjacent grazing field in terms of the spatial distribution of waste products, the biodiversity of trophic items stored in fecal pellets, and the C:N ratio as a predictor of nutrients supplied to the soil. We found that fecal pellets of mammal species were intermingled and spatially distributed throughout the entire landscape, but they were more abundant in the restoration area, indicating the influence of land management types on the distribution process. The two mammal species presented different feeding strategies; however, the plant species consumed in the grazing field indicate decreased food options for native mammals, meaning a smaller amplitude of their trophic niches under this land management. The low C:N ratio and the high nitrogen pool provided by the pellets in the restoration area suggest a potential benefit to plant communities. However, the higher organic C jointly with the lower C:N ratio observed in fecal pellets of grazing field indicate a low decomposability which could promote the conservation of C in the soil. [ABSTRACT FROM AUTHOR]

Clonal species Agave fourcroydes and A. sisalana from ancient crops have become invasive in Mediterranean drylands, posing a severe threat to ecologically valuable native plant communities. However, we barely know the relative contribution of clonal mechanisms underlying their invasive behaviour. Therefore, environmental managers must face this problem without scientific evidence on the most effective methods to eradicate or control these invasions. In this study, we monitored populations of A. fourcroydes and A. sisalana and carried out field and experimental plantings (in situ and under controlled environmental conditions) to assess the efficacy of three clonal mechanisms: shoots from rhizomes, shoots from rosettes, and aerial bulbils from floral scapes). Both species showed very similar performance in their clonal expansion. Shoot production from rhizomes was the primary mechanism for densifying Agave populations, emerging to the soil 1.5 ± 2.1 shoots per individual. Moreover, we did not observe mortality of new shoots from rhizomes. These new clonal individuals seemed to ensure their survival by connecting to the mother plant (clonal integration). In addition, contractile roots, only recorded in shoots from rhizomes, could represent an advantage allowing them to react to harsh environmental conditions. Regarding shoots from rosettes, individuals produced 0.63 ± 1.01 shoots on average, with no mortality recorded, but without guaranteeing the replacement of mother plants. Finally, bulbil production and their rooting under controlled and favourable conditions were very high, although their establishment success under arid conditions proved irrelevant. These results suggest that management actions should focus on the removal of shoots from rhizomes. This approach could be an efficient, feasible, and cost-effective medium- to long-term habitat management strategy to control these Agave invasions, with widespread application worldwide in similar invasion processes. [ABSTRACT FROM AUTHOR]

Blue Diamond cholla (Cylindropuntia multigeniculata (Clokey) Blackb. [Cactaceae]) is a rare cactus of the Mojave Desert. We explored whether cultivation from joint cuttings is a viable method for supporting threatened populations. Terminal joints were collected from adult plants at the type locality and grown in a shade house: We tested whether 2 soil mixes that varied in the ratio of inorganic and organic components (50:50 compared to 85:15) and 2 watering frequencies (250 ml every 5 d compared to 500 ml every 10 d) promote root growth important to outplanting survival. Plants grown from joint cuttings in the 50:50 soil had greater shoot and root biomass, produced more joint segments, and had higher initial and final survivorship over the 5-mo study. Neither soil nor watering treatments shifted biomass allocation to roots as hypothesized, but frequent watering produced longer roots, which may benefit reintroduced plants by assisting root access to deep soil moisture. Despite their vigor during collection, freshly cut joints rapidly declined in condition, resulting in approximately 50% mortality during the first month of the study. Initial mortality was not explained by the identity, condition, or size of the maternal plant. Prior-year weather patterns and collection procedures may influence quality and durability of joint cuttings and require further study. While larger plants were produced from the 50:50 mix, and root length was increased by frequent watering, reintroduction of nursery-grown plants will indicate whether such treatments aid establishment in the dry habitat where this species occurs. [ABSTRACT FROM AUTHOR]

Heavy metal-contaminated soil constitutes many environmental concerns. The toxic nature of heavy metals poses serious threats to human health and the ecosystem. Decontamination of the polluted soil by phytoremediation is of fundamental importance. Vegetation is an appealing and cost-effective green technology for the large-scale phytoremediation of polluted soils. In this paper, a greenhouse experiment was carried out to test the potential of Rhazya stricta as a heavy metal phytoremediator in polluted soil. Plants were grown for three months in pots filled with soils treated with the heavy metals Cd, Pb, Cu, and Zn at rates of 10, 50, and 100 mg/kg. The bioaccumulation factor (BCF) and translocation factor (TF) were calculated to detect the ability of R. stricta to accumulate and transfer heavy metals from soil to plant organs. The results showed that under increasing levels of soil pollution, the bioconcentration of Cd and Zn heavy metals showed the highest values in plant roots followed by leaves, whereas in the case of Pb and Cu, roots showed the highest values followed by stems. Heavy metals accumulation was higher in roots than in stems and leaves. The BCF of Zn reached the highest values in roots and stems for 10 mg/kg soil treatment, followed by the BCFs of Cd, Cu, and Pb. The TF for the different heavy metal pollutants' concentrations was less than unity, suggesting that the plants remediate pollutants by phytostabilization. The TF values ranged from higher to lower were in the order Zn > Cu > Cd > Pb. The rapid growth of R. stricta and its tolerance of heavy metals, as well as its ability to absorb and accumulate metals within the plant, recommends its use in the phytoremediation of slightly polluted soils in arid lands by limiting the heavy metals transport. [ABSTRACT FROM AUTHOR]