Arid Conditions Research Articles

The role of climatic variables on nest evolution in tanagers.

Avian nests are fundamental structures in avian reproduction and face strong selective forces. Climatic conditions are likely to have shaped the evolution of specific nest traits, but evidence is scarce at a macroevolutionary level. The Thraupidae family (commonly known as tanagers) is an ideal clade to understand the link between nest architecture and climate because it presents wide variation in nest traits. To understand whether climatic variables have played a role in the diversification of nest traits among species in this family, we measured nests from 49 species using museum collections. We observed that dome-nesting species are present in dryer and hotter environments, in line with previous findings suggesting that domed nests are a specialisation for arid conditions. We also found evidence that nests with thicker walls are present in locations with lower precipitation and that solar radiation can influence the shape of domed nests; birds tend to build shorter and narrower domes in areas with high levels of solar radiation. Open nest architecture is also potentially influenced by wind speed, with longer and deeper nests in areas characterised by strong winds. Our results support the hypothesis that different climatic variables can drive the evolution of specific aspects of nest architecture and contribute to the diversity of nest shapes we currently observe. However, climatic variables account only for a small fraction of the observed structural variation, leaving a significant portion still unexplained.

Development of yield prediction model for wheat by using AquaCrop model with different nitrogen dose applications in Central Anatolia Region (semi arid) conditions

In this study, yield prediction was made for Tosunbey and Bayraktar bread wheat varieties under rainfall conditions and 4 different fertilizer ratios with AquaCrop model, one of the plant growth models. In this experiment conducted at Haymana Ikizce Research Farm, actual field observations and model predicted grain yield, biomass, and green area coverage ratio were evaluated. Mean deviation (α), standard error (RMSE), and model efficiency coefficient (E) tests were used to determine the performance of the model. The AquaCrop model was calibrated in the first year and validated based on observational data collected in the first and second years of the experiment, respectively. Based on the results obtained, it was observed that the AquaCrop model simulated grain yield at different levels of nitrogen fertilizer applications with higher precision for Bayraktar variety. For Bayraktar variety, grain yield E = 0.93 in the first year and 0.99 in the second year for grain yield, and E = 0.83 in the first year and 0.98 in the second year for biomass, indicating excellent agreement between model and observation was found. In Tosunbey variety, first-year grain yield E=0.66 and 2nd year grain yield 0.76 were found. The 2nd year RMSE value for grain yield of Bayraktar variety was 0.266, and the 2nd year RMSE value for the grain yield of Tosunbey variety was 0.664 and found to be statistically compatible. Grain yield, biomass, and percent cover (CC) values obtained from the model were found to be highly consistent with field observations.

Opposite Hydrological Conditions between the Younger Dryas and the 8.2 ka Event Revealed by Stalagmite from Northwest Madagascar in East Africa

As prominent abrupt climatic events during the last deglaciation and the early Holocene, the Younger Dryas (YD) and the 8.2 ka events have been intensely discussed to reveal the relationship between their phases and intensities, and their underlying mechanisms based on massive marine and terrestrial archives. However, the related paleoclimate records with sufficient resolution and/or precise age constraints from the Southern Hemisphere, especially East Africa, are relatively sparse, hindering our comprehensive understanding about the phases of these two events. Here, we provide a precisely dated record of an aragonite-calcite stalagmite covering 11.3–13.5 ka BP from northwest Madagascar to unravel the arid conditions during the YD, in contrast to the pluvial conditions in the 8.2 ka event that has been evidenced before. Changes in austral summer precipitation related to the Intertropical Convergence Zone (ITCZ) have always been interpreted to be the primary means of controlling regional rainfall amounts and thus the δ18O variations in stalagmite. However, ITCZ’s meridional migration alone is not enough to interpret the opposite hydroclimatic conditions during the YD and the 8.2 ka events in northwest Madagascar. The variation in convection intensity within the ITCZ combined with the rainfall dipole mode in East Africa, and the redistribution of the duration of the ITCZ’s presence at different latitudes might be responsible for this phenomenon. In addition, sea surface temperature could play a nonnegligible role.

Оценка исходного материала и идеатип чины посевной в засушливых условиях нижнего Поволжья РФ

The results of screening of a model population of the Grass pea (Lathyrus sativus) are presented. The results of the study made it possible to establish the manifestations of the parameters of selection traits and their variability in the model population in the arid conditions of the Lower Volga region of the Russian Federation. The magnitude of the influence of factors on the manifestation of traits (genotype, growing conditions, interaction of factors) and their contribution to the overall variability has been established. Forms with high values of crop structure elements were identified: by the number of beans per plant, by the number of seeds per plant, by the mass of 1000 seeds, by seed yield (1,80-2,27 t/ha), by green mass yield (14,29 -21,77 t/ha). The parameters of the ideal type of grasspea variety adapted for cultivation in regions with arid climates are presented. Keywords: GRASSPEA, FACTOR, CONTENT, PARAMETER, YIELD

Impact of Cereal–Legume Intercropping on Changes in Soil Nutrients Contents under Semi–Arid Conditions

Cereal–legume intercropping systems are not well studied under the semi–arid conditions of Southern Tunisia. Therefore, the present study aimed to investigate the effect of intercropping durum wheat (Triticum turgidum ssp. durum L.) with chickpea (Cicer arietinum L.) on crop grain yield and soil physicochemical proprieties such as carbon (C) and nitrogen (N) availability, microbial biomass nutrients (C and N) and plant nutrient content (N) in comparison to their monocultures. Field experiments were conducted during the 2020–2021 (EXP–A) and 2021–2022 (EXP–B) seasons in Medenine, Tunisia. The results revealed a significant augmentation (p < 0.05) in the total nitrogen proportions (Ntot) within the soil of intercropped durum wheat (DuWh–IR) compared to its monoculture (DuWh–MC). The observed variations amounted to 32% and 29% during the two growing seasons, identified as EXP–A and EXP–B. Additionally, the soil of intercropped durum wheat (DuWh–IR) significantly (p < 0.05) accumulated more total carbon (Ctot) than the monocrop (DuWh–MC) for both experiments, showing an increase of 27% in EXP–A and 24% in EXP–B. Simultaneously, the N− uptake of durum wheat significantly increased under the effect of intercropping, showing a rise of 26% in the EXP–A season and 21% in the EXP–B season. Similarly, the yield of durum wheat crops was comparatively greater in the intercropped plots as opposed to the monoculture crops, with variances of 23% in EXP–A and 20% in EXP–B. Intercropping cereals and legumes has the potential to enhance the soil fertility and crop production in the semi–arid regions of Southern Tunisia and contribute to environmental sustainability by reducing reliance on nitrogen fertilizers.

Draft genome and SSR data mining of a Peruvian landrace of Capsicum chinense, the arnaucho chili pepper

AbstractThe Arnaucho chili pepper (ACP) is a traditional vegetable used in Peru because of its gastronomic properties. Due to its importance in the Peruvian diet and economy, this species is a resource that can be a candidate to plant breeding programs. In this study, the complete genome nucleotide sequence of this chili pepper was generated using the Illumina Hiseq 2500 sequencing technology. We sequenced the whole genome of the ACP using a paired-end 150 strategy, obtaining 330.46 GB of sequencing data. The genome size of the ACP was 2.98 Gb with a contig N50 of 237 Mb and 95.39% complete BUSCOs. Also, we identified 71.96% of repetitive DNA of the genome assembly, of which retroelements occupy 37.95% of the total genome. We downloaded genomes of the Solanoideae subfamily and conducted a comparative analysis of simple sequence repeats (SSRs) with our draft genome, and we identified lower number of SSRs in the ACP genome compared to other pepper species. This first ACP genome is expected to contribute to a better understanding of its genetics to adapt to the arid conditions of the Peruvian coastal ecosystem and evolution.

Paleoclimate changes across the Cenomanian–Santonian transition at the southern Neo-Tethys margin (SW Iran): An integrated approach

The Cenomanian–Santonian (C–S) carbonate successions include valuable petroleum reservoirs in the Zagros Basin. They also provide important information on the paleogeographic setting, paleoclimatic conditions, and tectonic evolution of the southern Neo-Tethys margin. This study focuses on the paleoclimatic changes across the C–S transition using the petrographical, petrophysical, paleontological, major and trace element and isotope geochemical data from three subsurface sections selected from the southern Dezful Embayment and northwestern part of the Persian Gulf. Remarkable differences in allochemical (skeletal and non-skeletal) elements indicate dissimilar paleoclimatic conditions during the Cenomanian–Turonian and Santonian. Paleoexposure events are related to diagenetic processes such as extensive meteoric dissolution (karstification) and the development of bauxitic–lateritic paleosols with high Fe, Al, and kaolinite concentrations indicating warm and humid (tropical) conditions. Increased values of Fe, Al, Rb, and 87Sr/86Sr isotopic ratios and depletion of Ca, Sr, δ18O, and δ13C considered together indicate meteoric diagenetic effects under this paleoclimatic condition. Spectral gamma measurements are used to investigate paleoclimatic conditions. Low content of Uranium (U) throughout the transgressive systems tract (TST) and high concentration in the regressive systems tract (RST) along with low contents of kaolinite within the Santonian sequence denote the predominance of arid conditions. The major fall in U concentrations at the Cenomanian–Turonian interface (CT-Exposure Surface) could be regarded as an outcome of the fall in the relative sea-level and a proxy of oxidizing conditions (Th/U > 7) that could be the consequence of a change in paleoclimate from humid/semi-humid to humid. Evidence for a 3–4 °C decrease in paleo-temperature and increase in aridity are recorded during the Cenomanian–Santonian transition in the Zagros Basin, which is in close agreement with global trends. This cooling pattern is attributed to a decline in atmospheric CO2 levels and alterations in oceanic circulation, specifically an increase in meridional circulation.

Quantitative facies analysis of a fluvio-aeolian system: Lower Triassic Buntsandstein Group, eastern France

Understanding the factors that control the temporal and spatial evolution of the Lower Triassic Buntsandstein Group, eastern France, is important not just for palaeoenvironmental reconstruction but also because it is an important reservoir for the lithium-rich geothermal brines in the Upper Rhine Graben region. The interval of interest in this study, the Lower Grès Vosgien Formation (LGV), is made up of c. 200 m of clastic deposits of mixed fluvial and aeolian origin. Given the proximity between the outcrops and the areas of mineral and heat exploration, this region offers a unique opportunity for quantitative analysis and correlation between outcrops and reservoirs. The LGV is the thickest Formation in the Buntsandstein Group. However, hitherto, no detailed architectural analysis has been published to reveal the controlling factors of its depositional elements. In this study, high-resolution facies analysis was applied to thirteen outcrops, and a core, to quantify fluvial and aeolian depositional architectures, and to comprehend palaeoenvironmental conditions during their deposition. Two facies associations were identified. The fluvial channel facies association, composed mainly of sandstones deposited in poorly confined, occasionally ephemeral channels, corresponds to 93 % of the total thickness. The analysis of >800 sets of strata characterised by lower-, transitional-, and upper-flow regime sedimentary structures, distributed within different architectural elements, enabled the distinction of temporal and spatial variabilities, and an estimate of fluvial palaeohydraulic characteristics. The wind- and water-laid facies association, which accounts for 7 % of the total thickness, records an architecture controlled by a fluctuating water-table level, and ephemeral floods. Results revealed that aeolian dunes and sand sheets accumulated in distinct temporal moments. The vertical trends, recorded in the core, indicate an upward increase in the frequency of intercalations between the two facies associations, and a decrease in the occurrences of thicker cross-bedded sandstone sets of fluvial origin, which, associated with the overall retrogradational stacking pattern of the LGV, is interpreted as the preserved record of a large distributive fluvial system (DFS). The occurrence of laterally extensive aeolian deposits, overlying fluvial deposits, is often associated by authors with periods of relatively more arid conditions at a regional scale. However, evidence indicates channel belt avulsion as an alternative interpretation for the establishment of the two facies associations. The findings enhance the knowledge about the depositional controlling factors in braided fluvial and aeolian systems, and improve predictive models that account for reservoir heterogeneity in accumulated successions of this type.

Ice? Salt? Pressure? Sediment deformation structures as evidence of late-stage shallow groundwater in Gale crater, Mars

Persistence of near-surface water during the late evolution of Gale crater, Mars, would have been fundamental for maintaining a habitable environment. Sedimentation in aqueous conditions is evident during the early stages of crater infilling, where accumulation of lower Mount Sharp group strata is characterized by fluviolacustrine sedimentary rocks. The basal unit of the Siccar Point group—the Stimson formation—which unconformably overlies the Mount Sharp group and represents conditions postdating the exhumation of Aeolis Mons, is characterized by accumulation of aeolian strata under arid conditions. Water was largely absent near the surface during its deposition. At the Feòrachas outcrop, discovery of soft sediment deformation structures in aeolian Stimson strata challenges the notion that Gale crater was devoid of water during its later depositional phase. We identified deformed wind-rippled and vertically laminated sandstones, hosted within erosion-resistant ridges forming boxwork patterns. Broadly, these structures are diagnostic of water (as liquid or as ice) in the shallow subsurface. Comparison with Earth analogues suggests formation by subsurface fluid escape, freeze-thaw processes, or evaporite deformation. Regardless of the mechanism, these structures signify the presence of water at or near the surface much later than previously documented and may extend the habitability window in Gale crater.

An assessment of pearl millet hybrids for drought tolerance under hyper arid conditions

An assessment of pearl millet hybrids for drought tolerance under hyper arid conditions

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.

Sedimentological evolution of the Quibas site: High-resolution glacial/interglacial dynamics in a terrestrial pre-Jaramillo to post-Jaramillo sequence from southern Iberian Peninsula

The sedimentary infill of the Quibas karstic site (Early Pleistocene, southern Spain) represents the only continuous succession with remains of continental vertebrates in Europe from pre-Jaramillo to post-Jaramillo age. The Quibas site, with a significant paleontological record, is dated between 1.1 and 0.9 Ma and offers a unique opportunity to carry out a paleoclimatic reconstruction of the time period immediately after the arrival of the first humans to western Europe. For this reason, defining the dominant sedimentary processes in the different stratigraphic units and the associated paleoenvironment is essential. The Quibas site is made up of two karstic features with two stratigraphic sequences: Quibas-Cueva, containing six lithostratigraphic units, and Quibas-Sima, which contains seven lithostratigraphic units. The detailed description and analyses of the stratigraphic sections have allowed the characterization of various autochthonous and allochthonous facies of cave deposits. Paleoclimatic proxies, inferred from sedimentological analyses, reveal a record of several alternating humid and arid phases resulting from the Early Pleistocene glacial-interglacial cycles, allowing correlation to the marine oxygen isotope record. The lowermost units (pre-Jaramillo) were deposited during a long-lasting interglacial, correlated to MIS 33–31. It was followed by an increase in aridity in the intermediate units of Quibas-Sima and uppermost unit of Quibas-Cueva (Jaramillo), revealing the beginning of a glacial period at the start of the Jaramillo subchron (1 Ma), which can be correlated to MIS 30. The upper Jaramillo and post-Jaramillo units suggest these were deposited in alternating periods of aridity and humid conditions, although less humid than the pre-Jaramillo period, probably representing the MIS 29 interglacial, the MIS 28 glacial and the MIS 27 interglacial.

Seasonal and isotopic precipitation patterns in the semi-arid and high mountain areas

Precipitation plays a crucial role in the natural hydrological cycle. Understanding the spatial and temporal variations of precipitation isotopes is essential for identifying hydrological, meteorological, and ecological processes. In high mountain areas with arid and semi-arid conditions, especially in regions with endorheic basins, the portion of precipitation that infiltrates the groundwater as the primary source of water recharge. However, estimating this recharge is challenging and prone to high uncertainty.The main objective of this study was to implement a robust and detailed methodology to analyze the influence of meteorological variables and the origin of moisture sources on the stable isotopic composition (δ18O and δ2H) of precipitation. As an illustrative case, we focused on the Los Pozuelos Basin, an endorheic basin in the Altiplano-Puna region of the Andes. The analysis incorporated precipitation samples collected over a 3-year period (January 2020 to April 2023) along with comprehensive monitoring of local atmospheric variables, satellite imagery, and HYSPLIT backward trajectory models.The examination involved a multivariate analysis of meteorological and stable isotope data and atmospheric transport pattern. Precipitation characteristics exhibited seasonal variability, with summer precipitation being depleted in heavy isotopes due to its extended continental journey and the recycling it undergoes while crossing the Amazon basin with convective activity. Another moisture path from the Atlantic Ocean, via the Río de la Plata or Gran Chaco basin, represented an intermediate isotopic stage. La Niña events intensified westerly winds, drawing moist air masses from the Pacific Ocean and causing rainfall in the study area. In winter, precipitation comes from the Pacific Ocean and isotopically enriched due to the low amount of precipitation and lower convective activity.By employing a meticulous methodology and multivariate statistical analysis, the study contributes positively to the broader discourse on water resource management and conservation in arid and semi-arid environments.

Land-surface quantitative analysis for mapping and deciphering the construction processes of piedmont alluvial fans in the Anti-Lebanon Mountains

Land-surface quantitative analysis based on digital elevation model (DEM) has been applied for improving the geomorphological mapping of piedmont alluvial fans. Indeed, these fans are frequently along a mountain front, where a series of coalescing fans may eventually occur. The margins of adjacent fans are rather difficult to map, thus preventing accurate and meaningful quantification of fan morphometric properties such as fan area, length, and slope. These morphometric properties are essential for informing on the influence of climatic conditions and tectonic factors on the fan-building processes. Therefore, in this paper, we propose a quantitative digital mapping approach along a stretch of about 50 km in the southern front of the Anti-Lebanon Mountains. Here, the Geomorphological Map of Syria at 1:1,000,000 scale (1963) reported at least nine piedmont alluvial fans, but these were poorly characterized in terms of geomorphometric characteristics and construction processes. Adopting the 1-arcsec SRTMv3 DEM, we propose a four-step workflow to analyse the feeding catchments morphology and fan morphometry. In this manner, the identification and geomorphological mapping of coalescent piedmont fans as well as the recognition of the main construction process have been improved. The proposed approach can support geomorphological investigations of wide and inaccessible areas—especially where arid and semi-arid climate conditions prevail—as well as where socio-political issues may prevent effective field work.

New record of conifer wood Agathoxylon from the Upper Jurassic in the Sichuan Basin, southern China, and its palaeobiodiversity and palaeoclimatic significance

ABSTRACT Although abundant and diverse foliage fossils are well recorded in the Upper Triassic and Lower–Middle Jurassic of the Sichuan Basin in South China, the Upper Jurassic plant fossils are rarely documented due to extensively developed red beds in this basin. Decades ago, abundant fossil wood specimens were discovered from the Upper Jurassic Penglaizhen Formation in the Sichuan Basin. However, detailed investigations on the systematic palaeobotany of these wood fossils are very limited, which hinders further understanding of the terrestrial ecosystem and biota. Here, we describe anatomically well-preserved fossil wood specimens from the Penglaizhen Formation at Wangjiagou Village of Shehong City in the central Sichuan Province. These wood fossils exhibit Agathoxylon anatomy with usually uniseriate contiguous radial tracheid pitting and araucarioid cross-field pitting, representing a new record of Agathoxylon in the Sichuan Basin, and contribute to further understanding of the vegetation composition of the southern phytoprovince in China during the Late Jurassic. Independent palaeoclimatic evidence from leaf, pollen and sediments indicates that the Agathoxylon trees from Shehong area have grown under generally hot and semi-arid or arid environmental conditions, probably in habitats at the banks of rivers and lakes with locally abundant water supply, as indicated by the indistinct growth rings.

Formation of the photoassimilation apparatus of pea (Pisum sativum L.) crops under biostimulants in arid conditions of the Southern Steppe of Ukraine

The Southern Steppe of Ukraine is characterised by a range of unfavourable agro-climatic conditions, which leads to inhibition of growth processes, disruption of physiological processes and loss of crop yields. The use of environmentally safe bioregulators stimulates growth processes, optimises nitrogen nutrition, increases the adaptability of legumes to adverse conditions and increases yields. The purpose of this study was to find out the specific features of the influence of biostimulants on the formation of the photoassimilation apparatus of pea of the Oplot variety in the Southern Steppe of Ukraine. A 3-year small-plot study was conducted to determine the leaf area index, total chlorophyll content, and net photosynthetic productivity in pea crops. The biostimulants were used for pre-sowing and foliar treatment of pea crops in the budding phase at concentrations described in the methodology. It was found that Stimpo (25 ml/t + 20 ml/ha) increased the leaf surface index in different stages of vegetation of pea variety Oplot by 1.12-1.54 times and Regoplant (250 ml/t + 50 ml/ha) increased the leaf surface index by 1.18-1.38 times compared to the control. A significant increase in the chlorophyll content in pea stipules was recorded after foliar treatment of crops with biostimulants and exceeded the value of control plants by 9.0-10.4% in the BBCH stages 61(65) – 75(79). Based on 3-year results, the positive impact of biostimulants on net photosynthetic productivity was proven. Thus, Stimpo and Regoplant increased the net photosynthetic productivity of pea crops by 35% and 22%, respectively, in the budding (BBCH 51-61) and flowering (BBCH 55-65) phases. The obtained scientific results contribute to the widespread use of the studied biostimulants in the technology of pea cultivation in the Southern Steppe zone of Ukraine to increase crop productivity and obtain a high-quality crop

Microbial survival strategies in biological soil crusts of polymetallic tailing wetlands

The role of biological soil crusts (biocrusts) in ecological restoration is dominated by microbiota. This has been extensively studied in arid ecosystems characterized by nutrient deficiencies and poor soil substrates, including metal(loid)-rich mining regions. However, in the prior study areas, water constraints obscured the toxicity and restriction of succession by heavy metals, which were essential for soil remediation in mining regions using biocrusts. Accordingly, in the current study, we characterized biocrusts from a typical polymetallic tailing wetland and performed pot incubation to evaluate microbial community succession and microbial co-occurrence patterns. Results showed that adequate water and heavy-metal stress produced thicker and more hydrophobic biocrusts than did arid conditions, promoting stronger microbial activity in tailing wetlands. Moreover, the bioinformatic analyses during pot incubation suggest three potential survival strategies. (1) Cyanobacteria variation improved the succession level of cyanobacterial crusts. Even under heavy-metal stress, succession from light to dark cyanobacterial crusts still occurred, with Coleofasciculaceae decreasing 63% and Scytonema increasing 59% compared with the control groups. (2) Keystone taxa variation maintained high inorganic nitrogen turnover. Organisms potentially capable of inorganic nitrogen turnover, including Chloroflexi A4b and SBR1031, maintained a high relative abundance accounting for 42% (15/36) of the keystone taxa. (3) Variations in the interactions among microbiota created closer-knit microbial networks. Compared with the control groups, fewer nodes (15.2%) maintained higher average clustering coefficient values (1.8%) through 14% more positive interactions in the groups exposed to heavy-metal stress at the end of the incubation experiment. This study provides insights into the distinctive survival strategies of biocrusts in metal-rich extreme environments, offering theoretical support for biocrust-mediated ecological restoration in humid metal-contaminated regions.

Changes in climate, vegetation cover and vegetation composition affect runoff generation in the Gulf of Guinea Basin

AbstractAlthough considerable effort has been deployed to understand the impact of climate variability and vegetation change on runoff in major basins across Africa, such studies are scarce in the Gulf of Guinea Basin (GGB). This study combines the Budyko framework and elasticity concept along with geospatial data to fill this research gap in 44 nested sub‐basins in the GGB. Annual rainfall from 1982 to 2021 show significant decreasing and increasing trends in the northern and southern parts of the GGB, respectively. Annual potential evapotranspiration (PET) also shows significant increasing trends with higher magnitudes observed in the northern parts of the GGB. Changing trends in climate variables corroborates with shift to arid and wetter conditions in the north and south, respectively. From 2000 to 2020 vegetation cover estimated using enhanced vegetation index (EVI) shows significant increasing trends in all sub‐basins including those experiencing a decline in annual rainfall. Vegetation composition measured using vegetation continuous fields (VCFs) from 2000 to 2020 show an increase in tree canopy cover (TC), a decline in short vegetation cover and marginal changes in bare ground cover (BG). Elasticity coefficients show that a 10% increase in annual rainfall and PET may lead to a 33% increase and 24% decline in runoff, respectively. On the other hand, a 10% increase in EVI may lead to a 4% decline in runoff while a 10% increase in TC, SV and BG may reduce runoff by 4% and increase runoff by 3% and 2%, respectively. Even though changes are marginal, decomposing vegetation into different parameters using EVI and VCFs may lead to different hydrological effects on runoff which is one of the novelties of this study that may be used for implementing nature‐based solutions. The study also demonstrates that freely available geospatial data together with analytical methods are a promising approach for understanding the impact of climate variability and vegetation change on hydrology in data‐scarce regions.

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.

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.