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Speleothem deposits in nowadays arid environments are important climate archives, as they indicate phases of enhanced precipitation and can precisely be dated by uranium-series dating. So far only very few of such archives have been found in the today hyper-arid Saharo-Arabian Desert (SAD). Therefore, the study at hand fills a gap that exists for speleothem climate archives in Northeast Africa. A new record from Saqia Cave (Central Eastern Desert, Egypt) documents for the first-time speleothem growth in Egypt for all sub-stages of MIS 5 and singular phases during MIS 6. Most important growth phases occur during periods of strong increase and maximum orbitally-forced northern hemisphere insolation, but also during phases of low insolation, which are in general attributed to aridity in North Africa. Here, at least semi-arid climate conditions are proposed for periods of low insolation during stadials of MIS 5. This suggests an impact of different possible sources of precipitation, apart from large scale shifts of the African monsoon, such as Red Sea Troughs, tropical plums and a larger spatial extent of the Mediterranean winter-rainfall zone. Concerning the spatial rainfall pattern in Egypt, we propose a considerable east to west rainfall gradient in Egypt for the Last Interglacial and suggest a stronger impact of variable moisture sources in the Eastern Desert near the Mediterranean and Red Sea in comparison to the more continental Western Desert of Egypt. This reveals more favorable pre-conditions for an enhanced land use potential in the past. Therefore, the more sustaining wetter climate in the Eastern Desert point to a recurring feasible dispersal corridor for Homo sapiens from the tropical climate into the temperate climate regime throughout MIS 5. Such a more humid climate provided an ideal basis for long-term, favorable environmental conditions east of the Nile Valley, creating a kind of contiguous landscape corridor that may have been attractive to humans and wildlife alike, linking the East African tropical climate regime with that of the temperate zone in Northeast Africa and Eurasia.

The Azraq oasis in the Eastern Desert of Jordan has produced considerable stone artefacts attributed to the early Palaeolithic, yet relatively few data are available regarding the chronology and palaeoenvironmental contexts of the remains. In this study, we present stratigraphic, sedimentological, and micropalaeontological analyses of the Late Acheulean site SM1 located within the former Shishan Marsh, which we combine with geochronological and sedimentological data from 13 neighbouring geological exposures to reconstruct landscape evolution at the western margin of the Shishan Marsh. We then discuss the Late Quaternary palaeolandscapes of the Greater Azraq Oasis Area over the past c. 350 ka. Our work demonstrates that the central Azraq Basin experienced three local wetting-drying cycles since the late Middle Pleistocene that would have dramatically shifted the quantity and distribution of freshwater resources, ranging from expansive wetland landscapes to desert refugia characterised by isolated spring pools—changes that would have significantly impacted the mobility decisions and settlement patterns of Palaeolithic inhabitants. Our study highlights that developing long-term records of human-environment dynamics in arid environments requires a mosaic approach to palaeoenvironmental reconstruction that is nested within a well-developed understanding of landscape evolution.

This paper presents the first insight into the interpretation of the wood charcoal from the Holocene layers of Wonderwerk Cave. Situated in the Northern Cape Province in the arid interior of South Africa, the site provides a unique and valuable chronological record of past environmental fluctuations and responding human behavioural adaptations spanning the last two million years. The Holocene strata have been dated to cover the last 12.5 ka cal BP years, but exclude the last 100 years because of contamination. A sizeable amount of charcoal was recovered from these strata and remnants have been identified, described and the species composition amongst the strata compared. Most identified species are those that tolerate hot, dry conditions, signalling an arid trend during the Holocene. Comparison with present day species distributions suggests an eastwards shift in modern vegetation. The charcoal data also indicate that during the mid Holocene there was a wetter period from 6.2 to 4.5 ka cal BP, coinciding with stratum 4a.

We have reassessed the palynological record of Equus Cave in the Savanna Biome of the southern Kalahari, one of the longest Late Quaternary pollen records for the semi-arid central interior of South Africa. We combined published pollen results from the cave, derived from hyena coprolites and the rubified deposits in which they occur, into a single sequence. By re-considering the chronology of this sequence, we critically evaluated the palaeoenvironmental record for the site. We compared the pollen evidence from Equus Cave to that from the longer Wonderwerk Cave records (stalagmite, sediments and dung), also located in the Savanna Biome. Then, we contrasted Equus and Wonderwerk records with other previously published pollen sequences derived from a range of sources from several sites in central South Africa. These sites follow a broad northwest to southeast transect of c. 500 km through the Grassland and Nama Karoo Biomes of the Free State and Eastern Cape. Applying Principal Components Analysis to the pollen data, we derived climatic signals at a regional scale to refine reconstructions of Late Quaternary changes for central South Africa., LS was supported by the National Research foundation (South Africa) (NRF Grant no. 85903). The Leakey Foundation (USA) and the National Science Foundation (USA) respectively supported CBB’s work at Baden-Baden and Blydefontein. LS appreciates Juan Ochando Tomas’ collaboration relating to hyena coprolites in Project CGL-PID2019-1049449GB-I00 (FEDER/Ministry of Science and Innovation, Spain).

The Yangtze River is a major component of the ‘Asian Water Tower’ and it provides freshwater resources for hundreds of millions of people in East Asia. Hence, climatic and environmental changes in the source region of the Yangtze River (SRYR) are of major significance for understanding changes in the status of its freshwater resources. However, due to the contradictory results shown by the available paleoclimatic records from the SRYR and neighboring regions, it remains unclear how the regional climate and hydrology have evolved since the middle Holocene. Here, we present records of hydrological variations based on multiple proxies (grain size, scanned micro-scale X-ray fluorescence (XRF) element composition, and loss on ignition (LOI)) of the sediments of alpine lake Saiyong Co, with the aim of reconstructing hydrological changes in the SRYR since 5.8 ka. The first principal component (PC1) of the XRF scanned element record is dominated by Ti, Fe and K, representing terrigenous inputs from the catchment. The LOI profile shows an inverse pattern of variation to that of PC1, suggesting that the sedimentary organic matter is primarily derived from aquatic plants. Since 5.8 ka the overall decrease in sample scores on PC1 and the increasing LOI, together with the grain-size based lake-level record, indicate an overall drying trend in SRYR. Furthermore, several major droughts are recorded, at ∼4.0 ka, ∼2.8 ka and ∼1.8 ka. The hydrological variations at Saiyong Co are supported by multiple records from the SRYR, suggesting that millennial-scale environmental variations were regionally synchronous and were influenced by Northern Hemisphere summer insolation and movement of the intertropical convergence zone.

This work analyze the technological management of raw materials and the mobility strategy of the human groups that occupied during the mid-Holocene (ca. 8000-3000 BP) the eastern Tandilia mountain range, and discuss them inside of settlement systems context for the southeastern Pampean region. The lithic study results of 13 occupations excavated in caves and rockshelters shows that mobility strategies in Tandilia mountain ranges were closer to collector models, where logistical groups moved into mountain range valleys in search of natural resources. We can recognize different strategies for raw material procurement: the immediately available rocks were obtained through direct access on daily foraging trips; the regional rocks were obtained through logistical displacements, residential movements and embedded strategies; and the access to the long distance rocks was through exchange between neighboring populations. Besides, during ca. 7000 to 5000 cal BP an increased use of immediately available raw materials and a high archaeological signal was detected. This scenario can be linked with an increased environmental aridity episode where human groups occupied with most intensity the Tandilia mountain valleys due to the greater availability of the water resources. Finally, this work provides new data suggesting that during this period in the southeastern Pampean region context, the hunter-gatherer groups combined forager and collector strategies to take advantage of the natural resources of the landscape with diverse environments (coastline, grassland plains, dunes field and mountain ranges).

As a common measure for grassland restoration, the fence for prohibition of grazing is usually applied to the steppe in northern China. A study in Hulunbuir grassland showed the average litter mass in the steppes that enclosed for ten years can reach 70-550g/m2. The excessive accumulation of litter caused by long-term grazing prohibition can intercept more precipitation, which will reduce the water available to grassland plants and hinder the further recovery of plant communities. Therefore, the establishment of a reasonable litter interception model can help estimating the interception of steppes with different litter accumulation and provide some theoretical support for the formulation of fencing policies. Based on the model of litter interception rate change, we established a dynamic interception model of litter: I = I m ( 1 − e − k t ) ( t : time; I : dynamic interception; I m : maximum interception; k : exponential coefficient of litter interception). After testing by an indoor simulated rainfall experiment, we found that this model has high accuracy ( R 2 : 0.908 – 0.992). The litter mass (LM) determines the maximum interception, and the rainfall intensity (RI) determines the speed of interception which reaches its maximum value. After the conversion of coefficients, we established a prediction model of litter interception based on LM and RI: I = ( 0.003 L M + 0.44 ) [ 1 − e − ( 0.33 R I + 3.76 ) t ] , R 2 = 0.86 , P 0.001 . The easily obtainable characteristics of LM and RI data make this model easy to apply.

The absence of large archaeological settlements in the Eastern Arabian Peninsula suggests that most of the recent wet periods occurring during climate oscillations in these areas were short-lived. However, a ∼ 2-by-3-km buried rectangular feature was discovered opportunistically in the southeast of the Qatar Peninsula while performing radar subsurface mapping of structural conduits for groundwater characterization. The feature is characterized by its unique contrasting patterns of surface and subsurface roughness as well as its organic-rich mixture of soils, as assessed from high-resolution radar and multispectral observations, respectively, and validated with GPR and EM subsurface probing. The above characteristics could be the only remaining evidence for a large primitive settlement due to the harsh erosive setting. To explore the natural or anthropogenic origin of this anomalous feature, we compare its dimensions, structural setting, roughness, and composition to similar formations in the Qatar Peninsula and other arid karst environments. Findings suggest that the feature is texturally and compositionally unique within the Qatar Peninsula, and is not reproduced in other arid karst terrains nor reproduced by the fracture patterns associated with the Qatar-South Fars Arch. We hypothesize that the feature is a karst depression modified by semi-stationary primitive human settlements ∼ 3640 BP or earlier based on radiocarbon dating of in-situ charcoal samples. Moreover, the organic-rich mixture of soil and the occurrence of several symmetrical features observed inside the perimeter suggest that landscaping, farming and irrigation activities could have occurred within the site, further suggesting that long-lasting wet conditions—with sufficient fresh water resources or reliance on karst aquifers—were able to sustain a relatively large primitive settlement not previously witnessed in the region’s archaeological record. Future improvements in the resolution and coverage of orbital L-band radar observations, as used above, can provide new insights into understanding prehistoric human occupation under fluctuating climatic conditions and groundwater dynamics in these hyper-arid regions.

Temporal and spatial changes of green water (GW) security due to climate and land-use/land-cover (LULC) changes can be used to make the best decisions for sustainable GW management. In this study, simultaneous effects of climate and LULC changes on water resources in Kashafrood Basin were evaluated using the Soil and Water Assessment Tool (SWAT). A land change modeler was set up to monitor LULC, assess changes and make predictions. The MIROC-ESM model derived from Coupled Model Intercomparison Project Phase 5 under two representative concentration pathway (RCP) emission scenarios RCP2.6 and RCP8.5 was applied to evaluate the effects of climate change. Two indices of GW-Scarcity and GW-Vulnerability, representing GW-Security, were quantified using the GW-Footprint concept in Kashafrood Basin. The results show that the annual average of blue water was predicted to increase by 142–350%, and GW storage and the annual averages of GW flow were predicted to decrease by 12–65 and 8–20%, respectively, depending on emission scenarios and time. The GW-Security estimates in the entire basin suggest a better condition in the future by indicating 24–45 and 16–52% decreases in GW-Scarcity and GW-Vulnerability, respectively, depending on emission scenarios and time. HIGHLIGHTS Land change modeler predicts a decline in agricultural area and a growth in urban and pasture areas.; Blue water rises by 142–350% under the effect of climate and land-use changes.; Green water (GW) storage and GW flow decrease by 12–65 and 8–20%, respectively.; The condition of the basin in terms of GW-Security would improve in the future.; GW-Scarcity and GW-Vulnerability escalate in southern and some western subbasins.

The degradation and desertification of grasslands pose a daunting challenge to China's arid and semiarid areas owing to the increasing demand for them in light of the rise of animal husbandry. Monitoring grasslands by using big data has emerged as a popular area of research in recent years. As grassland degradation is a slow and gradual process, the accurate identification of grassland cover is key to monitoring it. Vegetation coverage is currently monitored mainly by combining inversion-based methods with field surveys, which requires significant human effort and other resources and is thus unsuitable for use at a large scale. We proposed to use time series from the enhanced vegetation index (EVI) in capsule network-based methods to identify grasslands. The process classified grassland coverage into four levels, high, medium, low, and other, based on Landsat images from 2019. The accuracy in classifying the grasslands at each level was higher than 90%, with an overall accuracy of 96.32% and a kappa coefficient of 0.9508. The proposed method outperformed the SVM, RF, and LSTM algorithms in terms of classification accuracy.

© 2021 John Wiley & Sons, Ltd.Basins with hydrological modifications pose challenges in hydrological modelling, especially when there are limited data about basin characteristics. Models, however, are vital if we are to identify undisturbed hydrological conditions and evaluate the extent of modifications. In this study, we used SWAT to model the hydrological processes in a semi-arid closed basin, where basin hydrology was heavily modified with reservoirs and irrigation canals and drains. Modelling was also challenging due to limited data about basin characteristics and irrigation management. We modelled the hydrological processes using topographic, land use/cover, soil and climate data. The auto-irrigation tool in SWAT, which determines the timing and amount of irrigation based on the plant water stress factor, was used to represent irrigation. We successfully calibrated/validated the model for streamflow and reservoir storage and confirmed it further by analysing simulated water volumes in wetlands collecting drainage flows. We used the model to simulate the undisturbed hydrologic state and the effects of intensified irrigation. This study showed that SWAT can provide reasonable predictions of hydrological processes in agricultural basins where the natural flow regime is altered by man-made structures. Simulations with the model revealed that the construction of reservoirs followed by land use changes and intensified irrigation have affected streamflows and downstream ecosystems significantly.

En ambientes áridos y semiáridos la disponibilidad de agua es el factor principal que controla los procesos biológicos. En un pastizal de la Estepa Magallánica Seca, sur de Santa Cruz, se instaló un ensayo de intercepción de lluvias con el fin de evaluar los cambios en la disponibilidad hídrica en la superficie del suelo. Se realizaron tres tratamientos: sequía con intercepción del 50% (simula año seco), testigo y un tratamiento con riego (50% más de lluvia en el verano). Cada tratamiento tuvo tres repeticiones y en todos los casos se excluyó el pastoreo. El experimento contó con sensores de potencial hídrico mátrico (MPS-6) y temperatura de suelo (un sensor Decagon ECT por parcela a 10 cm de profundidad), y un pluviómetro (Decagon device ECRN – 100), todos conectados a un logger Decagon EM50 con frecuencia de registro horaria. La hipótesis de este trabajo fue que el riego durante el verano evitaría que el suelo se seque y que la intercepción de lluvia generaría un período seco más intenso y prolongado durante esta estación. En general, el suelo estuvo húmedo en el tratamiento irrigado, aunque se generaron breves períodos secos en los casos de lluvias escasas entre riegos. Las parcelas de intercepción tuvieron un período seco más intenso y más prolongado en el tiempo tal como se supuso, pero esto ocurrió solamente en el otoño. A principios de invierno el suelo alcanzó valores de capacidad de campo y permaneció así durante la primavera. Los períodos secos en la superficie del suelo fueron breves, ocurrieron en la estación cálida y dependieron de las lluvias estivales.

Previous studies on tidal flood mapping are mostly through continental- and/or global-scale approaches. Moreover, the few works on local-scale perception are concentrated in Europe, Asia, and North America. Here, we present a case study approaching a tidal flood risk mapping application in the face of climate change scenarios in a region with a strong environmental and social appeal. The study site is an estuarine cut in the Brazilian semi-arid region, covering part of two state conservation units, which has been suffering severe consequences from tidal flooding in recent years. In this case study, we used high-geodetic-precision data (lidar DEM), together with robust tidal return period statistics and data from current sea level rise scenarios. We found that approximately 327.60 km2 of the estuary is under tidal flood risk and in need of mitigation measures. This case study can serve as a basis for future management actions, as well as a model for applying risk mapping in other coastal areas.

As the third most important greenhouse gas, nitrous oxide (N2O) poses a significant threat to global warming and the ozone layer. However, the effects of precipitation changes on N2O emissions in arid areas remain unclear, particularly in desert steppe environments. Therefore, an in situ control experiment was conducted from July 2018 to July 2020 to examine the N2O emissions with changes in precipitation in the Urat Desert Steppe, northwestern China. The results showed that the N2O emission rate was relatively low in this desert steppe, at −0.04 to +15.0 μg N m−2 hr−1 with an annual flux of 0.20 ± 0.03 kg N ha−1. An increasing trend of N2O emission was observed in the early growing season (February to June 2019) when the precipitation was increased by 40% and 60% of its natural level. In contrast, no significant change in N2O emissions was observed when the precipitation was decreased during the same period. During the middle and late growing season and in the nongrowing season, precipitation changes did not significantly affect N2O emissions. In particular, no significant change in the annual N2O flux was observed during the entire observation period whether the precipitation was increased or decreased. Furthermore, the results of a structural equation model showed that the most important controlling factor for N2O emission is an abundance of key functional ammonia monooxygenase genes of ammonia-oxidizing archaea, which are restricted by the soil NH4+-N content, followed by abundances of key functional NO2− reductase (nirK) and N2O reductase (nosZ) genes. In contrast, the indirect effect of soil moisture on the abundance of nosZ compensated for the direct effect of soil moisture on N2O emissions. These results show that the primary and secondary origins of N2O emissions are soil ammonia oxidation and soil denitrification processes, respectively. In these two processes, N2O emissions are influenced more by the abundance of key functional microorganisms than by soil moisture, which might be limited mainly by the available soil nitrogen. Overall, the N2O emissions in the desert steppe environment were not sensitive to precipitation changes and were regulated mainly by nitrogen-related key functional microorganisms.

Groundwater in arid areas is critical for drinking water supplies, irrigated agriculture, and the preservation of terrestrial ecosystems. In the semi-arid region of Guenfouda, shallow aquifers are vital for human habitation and agriculture. Many settlements acquire their water from wells and springs. However, these wells are particularly susceptible to seasonal fluctuations and may be depleted during dry periods. Therefore, a deeper understanding of the hydrogeology of deep aquifers is required. Using analysis of geologic and hydrogeologic data in a GIS environment, this study examined the efficiency of the gravity model in investigating the structure of deep aquifers. A combination of filtering techniques was applied on the gravity map. The developed model shows the general configuration of the Jurassic aquifer, which gradually dips to the north and northeast to a depth of about 2280 m. Statistical analysis revealed considerable spatial coherence between fractures and compartments of the aquifer. Consequently, the structural model obtained from gravity data can greatly improve our understanding of the aquifer structure in the survey area.

Context Vegetation patterns in hummock grasslands of Australia’s arid interior can be very complex. Additionally, the grasslands are interspersed with variable amounts of trees and shrubs. Objectives To better understand the spatial arrangement of this vegetation structure, and in particular the unvegetated bare-soil gaps, we analyzed the scale-dependent patterns of gaps, trees, and shrubs. Methods We focused on two size categories of grassland gaps, large gaps ≥ 4 m2 known as fairy circles (FCs) and small gaps 1 to 2, and on trees and shrubs. We mapped four 200 m × 200 m study plots located east of the town of Newman in Western Australia, using drone-based aerial images and LiDAR. The RGB images were converted into binary images and the gaps and woody plants were automatically segmented. The spatial patterns of the four vegetation components were analyzed, as well as the shape properties of the vegetation gaps. Results The most striking result was that small gaps appeared consistently at about 5 m distance away from the FCs, which are known as the most water-depleted locations in the grassland. The FCs were also rounder than the small gaps and this symmetry underlines their function as an extra source of water for the surrounding matrix vegetation. Trees and shrubs had spatial patterns that were unrelated to FCs, which likely results from their water uptake in deeper sub-soil layers. Conclusions The consistent distance of small gaps to FCs is further support that the Australian fairy circles are a self-organized vegetation pattern that results from ecohydrological feedbacks.

Proterozoic basement aquifers are the primary source of water supply for the local populations in the Aseer (also spelled “Asir” or “Assir”) province located in the southwest of Saudi Arabia (SA) since high evaporation rates and low rainfall are experienced in the region. Groundwater assets are receiving a lot of attention as a result of the growing need for water due to increased urbanization, population, and agricultural expansion. People have been pushed to seek groundwater from less reliable sources, such as fracture bedrocks. This study is centered on identifying the essential contributing parameters utilizing an integrated multi-criteria analysis and geospatial tools to map groundwater potential zones (GWPZs). The outcome of the GWPZs map was divided into five categories, ranging from very high to negligible potential. The results concluded that 57% of the investigated area (southwestern parts) showed moderate to very high potentials, attributed to Wadi deposits, low topography, good water quality, and presence of porosity and permeability. In contrast, the remaining 43% (northeastern and southeastern parts) showed negligible aquifer potential zones. The computed GWPZs were validated using dug well sites in moderate to very high aquifer potentials. Total dissolved solids (TDS) and nitrate (NO32−) concentrations were highest and lowest in aquifers, mainly in negligible and moderate to very high potential zones, respectively. The results were promising and highlighted that such integrated analysis is decisive and can be implemented in any region facing similar groundwater expectations and management.

Grain production stabilization is one of the main criteria for the development of agriculture in Russia. In this regard, in modern breeding, when developing varieties, considerable attention must be paid to their adaptability, i.e. parameters that ensure stable productivity in various growing conditions. The purpose of the current study was to estimate the spring barley samples according to the trait ‘yield’ for adaptability to the arid conditions of the Stavropol Territory and their further use in breeding work. The material for the study were 86 spring barley samples. In order to determine the stability, there was used a variance coefficient (V%) according to the method of B.A. Dospekhov (2014). The ecological adaptability (bi) and the environment index (Ij) were determined according to the method of S.A. Eberhart and W.A. Russell (1966) as presented by V.Z. Pakudin (1984). Homeostaticity (Hom) was assessed according to the method of V.V. Hangildin (1981). Stress resistance was determined according to the equations of A.A. Rosielle and J. Hamblin as presented by A.A. Goncharenko (2005). There were identified the highly productive samples ‘Mamlyuk’ (389 g/m2) and ‘Stirling’ (378 g/m2), possessing high responsiveness to improving environmental conditions (bi = 1.44–1.21), variability (V = 58.9–51,2%) and low stress resistance (Ymin – Ymax = -538–488). Such genotypes are capable of forming high yields in favorable conditions and may be of interest for breeding high-intensity varieties. The samples weakly responsive to changes in growing conditions were distinguished by high stability and homeostaticity according to the trait ‘yield’, namely ‘Nutans 74840’ (Hom = 2.88; V = 38.4%) and ‘Veles’ (Hom = 2.56; V = 38.5%), as well as the adaptable variety ‘Getman’ (Hom = 2.89; V = 40.6%). These samples are the most adaptive to the arid conditions of the Stavropol Territory and regions with similar cultivation conditions. They are recommended for use in breeding work.

Glaciers in the central Qilian Mountains provide important water resources for the arid Hexi corridor and Qaidam Basin; however, changes in these glaciers interact with climate change. Twenty-four bi-static image pairs of TerraSAR-X add-on for Digital Elevation Measurement (TanDEM-X) data, in addition to a Shuttle Radar Topography Mission-C/X band digital elevation model, and the technology of iterative differential synthetic aperture radar interferometry were used to carry out glacier elevation change analysis in the central Qilian Mountains in China during 2000–2014. Glacier elevation changed with an average rate of (−0.47±0.06) m yr−1, while changes in elevation of (−0.51±0.06) m yr−1 and (−0.44±0.06) m yr−1 were found in the northern (including the Zoulangnan, Tuolai, and Tuolainan mountains) and southern (including the Shulenan and Hark mountains) regions, respectively. Summer mean temperature has risen by 0.51°C (10 yr)−1 in the northern region and 0.48°C (10 yr)−1 in the southern region during 1989–2014; however, the change in amplitude of annual precipitation was 2.69 mm yr−1 in the northern region and 4.77 mm yr−1 in the southern region for the same period. These changes can be ascribed as major driving factors for the differences in the changes in glacial elevation in the northern and southern regions. Four types of glaciers existed in the region when considering the change in elevation of the glacial tongue and variation in the position of the glacial terminus: surging, advancing, intensively retreating, and slightly retreating glaciers. If elevation decreased more than 20 m on the part of glacier tongue, the glacier terminus position had commonly retreated more than 100 m.

As one of the key determinants of water availability in arid regions, groundwater plays an essential role in regulating biodiversity, key ecosystem processes and functioning. Meanwhile, biodiversity is known to modulate ecosystem functions. Numerous studies have focused on the links between aboveground productivity and plant diversity, while the potential influence of root traits on fine root biomass (FRB) has barely been elucidated. Therefore, it remains unclear how groundwater, soil, species diversity, above- and belowground traits jointly regulate FRB. 230 plots were sampled under a broad range of groundwater and soil conditions across a typical arid inland river basin, within which FRB, associated soil properties, species diversity and functional traits were measured. FRB was mainly regulated by the interactions between groundwater and root trait diversity, followed by groundwater, root trait diversity and soil moisture. Although mean and seasonality of groundwater depth had substantial effects on FRB, groundwater affected FRB mainly through indirect pathways mediated by root trait diversity. Furthermore, root trait diversity showed the largest direct effect on FRB, suggesting that it was the main driver of FRB. Species richness and aboveground traits had no significant direct effect on FRB, implying that root traits surpassed species richness and aboveground traits in regulating FRB. Our findings provide robust empirical evidence that groundwater and root trait diversity jointly drive existing belowground carbon storage in arid inland river basin. We emphasize the importance of groundwater and root trait diversity, as well as their interactions in forecasting underground ecological processes and functions under global changes.

Many regions across the globe are shifting to more arid climates. For shallow lakes, decreasing rainfall volume and timing, changing regional wind patterns and increased evaporation rates alter water regimes so that dry periods occur more frequently and for longer. Drier conditions may affect fauna directly and indirectly through altered physicochemical conditions in lakes. Although many studies have predicted negative effects of such changes on aquatic biodiversity, empirical studies demonstrating these effects are rare. Global warming has caused severe climatic drying in southwestern Australia since the 1970s, so we aimed to determine whether lakes in this region showed impacts on lake hydroperiod, water quality, and α, β and γ diversity of lake invertebrates from 1998 to 2011. Seventeen lakes across a range of salinities were sampled biennially in spring in the Wheatbelt and Great Southern regions of Western Australia. Multivariate analyses were used to identify changes in α, β and γ diversity and examine patterns in physicochemical data. Salinity and average rainfall partially explained patterns in invertebrate richness and assemblage composition. Climatic drying was associated with significant declines in lake depth, increased frequency of dry periods, and reduced α and γ diversity (γ declined from ~300 to ~100 taxa from 1998 to 2011 in the 17 wetlands). In contrast, β diversity remained consistently high, because each lake retained a distinct fauna. Mean α diversity per-lake declined both in lakes that dried and lakes that did not dry out, but lakes which retained a greater proportion of their maximum depth retained more α diversity. Accumulated losses in α diversity caused the decline in γ diversity likely through shrinking habitat area, fewer stepping stones for dispersal and loss of specific habitat types. Biodiversity loss is thus likely from lakes in drying regions globally. Management actions will need to sustain water depth in lakes to prevent biodiversity loss.

This editorial introduces the Australian Journal of Botany special issue ‘Vegetation science for decision-making’. Vegetation science and classification are crucial to understanding Australian landscapes. From the mulga shrublands of the arid interior to the monsoon rain forests of northern Australia, we have culturally and scientifically built upon the delineation of vegetation into recognisable and repeatable patterns. As remote sensing and database capacities increase, this improved capability to measure vegetation and share data also prompts collaboration and synthesis of complex, specialised datasets. Although the task faces significant challenges, the growing body of literature demonstrates a strong discipline. In Australia, purpose-driven products describe vegetation at broad scales (e.g. the National Vegetation Information System, the Terrestrial Ecosystem Research Network). At fine scales however (i.e. that of the vegetation community), no uniform framework or agreed protocols exist. Climate and landform dictate vegetation patterns at broad scales, but microtopography, microclimate and biotic processes act as filters at finer scales. This is the scale where climate-change impacts are most likely to be detected and effected; this is the scale at which a deeper understanding of evolutionary ecology will be achieved, and it is the scale at which species need to be protected. A common language and system for understanding Australian communities and impetus for collecting data at this scale is needed. In the face of ongoing climate and development pressures and an increasingly complex set of tools to manage these threats (e.g. offset policies, cumulative impact assessments), a nationally collaborative approach is needed. It is our hope that this special issue will help to achieve this.

Loss and degradation of soil due to water erosion is among the most well-known types of worldwide land disturbance, specifically in arid and semi-arid areas. The complexity of the erosion study breaks the problem of comprehensively understanding all the factors that significantly affect this process. Water erosion is triggered when the retention capacity of soils is less than the amount of rainfall, which promotes surface runoff. The latter, under unfavourable environmental conditions, becomes the principal cause of water erosion. This study aims to use the geographic information system and remote sensing techniques to assesses and evaluate the soil losses under semi-arid climate conditions using the revised universal soil loss equation model (RUSLE) in comparison to a new approach based on surface erosive runoff (RUSLErunoff). The study zone is Wadi Soubella Watershed, NE of Algeria which, extends on 185 km2 in the East part of the Hodna basin. The results show that the Wadi Soubella Watershed is affected by low to moderate and rarely by high soil losses, with various rates between 0 to 100 t km−2 year−1 and rarely reaching 300 t km−2 year−1. The most affected areas with intense erosion pressure occur in the foothills of the mountains (Djbel Mouanich, Ras Tenndar, Kef el Assa and Djebel Soubella) and the bare land degraded areas. The relationship analysis (slope–erosion) using the RUSLErunoff model showed that soils subject to steep slopes and high vegetation cover (forest) are more vulnerable than other land-use classes, showing the effect of the surface erosive runoff. The root mean square error between the observed values according to the two models show that low slope class and the steep slope class show that RMSE is higher than the RMSE in mid-class slope with (54 t km−2 year−1 and 130 t km−2 year−1) and (13.54 t km−2 year−1 and 14.47 km−2 year−1), respectively. The comparison between the two models showed a satisfactory power regression with R2 = 0.49 and r = 0.7. In deduction, the relationship from the integration of surface erosive runoff as a factor for the soil loss estimation in the Wadi Soubella Watershed is exponential. The protective behaviour of forest cover is shown more clearly by the RUSLErunoff model than the RUSLE model.

Bolboschoenus planiculmis is a key wetland plant in the semi-arid regions of Songnen Plain, China, providing food and habitat for the endangered Siberian crane. B. planiculmis wetlands are being degraded by water shortages caused by anthropogenic activities and climate changes. However, the vegetation dynamics under hydrological fluctuations have been rarely reported. We conducted a two-year field investigation in B. planiculmis wetlands to determine the vegetation response to water level changes, and a comparative control experiment to examine the restoration effect of supplemental water on degraded community. We found that the community biomass was positively related with water depth under natural conditions, whereas plant diversity and richness were negatively related. The population density, biomass, and root/shoot ratio of B. planiculmis exhibited quadratic relationships with water depth. The optimum ecological threshold of water depth determining B. planiculmis populations was 11.2–36.1 cm. The control experiment demonstrated that water depth at 0–10 cm during the early growing season and 10–25 cm at later growing stages can enhance the dominance of B. planiculmis and help it outcompete other macrophyte species. Understanding the water requirement cycles of B. planiculmis is valuable for guiding water management plans for the rehabilitation of degraded natural wetlands.

BackgroundThe ecosystem classification of land (ECL) has been studied for a couple of decades, from the beginning of the perfect organism system “top-down” approach to a reversed “bottom-up” approach by defining a micro-ecological unit. After comparing two cases of the ecosystem classification framework implemented in the different continental ecoregions, the processes were carefully examined and justified.ResultsTheoretically, Bailey’s upper levels of ECL (Description of the ecoregions of the United States, 2nd ed. Rev and expanded (1st ed. 1980). Misc. Publ. No. 1391 (Rev). Washington DC USDA Forest Service; 1995) were applied to the United States and world continents. For the first time, a complete ECL study was accomplished in Western Utah of the United States, with eight upper levels of ECOMAP (National hierarchical framework of ecological units. U.S. Department of Agriculture, Forest Service, Washington, DC.https://www.researchgate.net/publication/237419014_National_hierarchical_framework_of_ecological_units; 1993) plus additional ecological site and vegetation stand. China’s Eco-geographic classification was most likely fitted into Bailey’s Ecosystem Classification upper-level regime. With a binary decision tree analysis, it had been validated that the Domains have an empty entity for 500 Plateau Domain between the US and China ecoregion framework. Implementing lower levels of ECL to Qinghai Province of China, based on the biogeoclimatic condition, vegetation distribution, landform, and plant species feature, it had classified the Section HIIC1 into two Subsections (labeled asi,ii), and delineatediiaof QiLian Mountain East Alpine Shrub and Alpine Tundra Ecozone intoiia-1andiia-2Subzones. Coordinately, an Ecological Site was completed at the bottom level.Conclusions(1) It was more experimental processing by implementing a full ECL in the Western Utah of the United States based on the ECOMAP (1993). (2) The empty entity, named as Plateau Domain 500, should be added into the top-level Bailey’s ecoregion framework. Coordinately, it includes the Divisions of HI and HII and the Provinces of humid, sub-humid, semiarid, and arid for China's Eco-Geographic region. (3) Implementing a full ECL in a different continent and integrating the lower level's models was the process that could handle the execution management, interpreting the relationship of ecosystem, dataset conversion, and error correction.

Soil moisture is a limiting factor for vegetation restoration on the Loess Plateau, China. Micro-topography may cause heterogeneities in the distribution of soil moisture, but little is known about its effect on deep soil moisture. Our study aims to explore the distribution and impact of soil moisture within the upper 10 m of soil for different microtopographies. Taking undisturbed slope as the control, five micro-topographies were selected. Soil moisture over a depth of 0–10 m from 2017 to 2019 was investigated, and soil particle size and soil organic matter were measured. Variance analysis and multiple comparisons were used to analyze the difference in soil moisture for different microtopographies and multiple-linear regression was used to analyze the influence of micro-topography on soil moisture. There are significant differences in soil moisture within the different layers underlying the examined micro-topographies, while the inter-annual variation in soil water storage for the selected microtopographies increase with increased rainfall. The depth of influence of micro-topographic vegetation on soil moisture exceeded 1000 cm for a gully (GU), 740 cm for a sink hole (SH), 480 cm for a scarp (SC), 360 cm for an ephemeral gully (EG) and 220 cm for a platform (PL). Micro-topography will cause the heterogeneous distribution of soil moisture in the shallower layers, which changes the vegetation distribution differences between micro-topographies. This may be the survival strategy of herbaceous vegetation in response to climate change in the Loess Plateau. For future vegetation restoration efforts, we need to pay attention to the influence of microtopography on soil moisture.

Intense human activities in arid areas have great impacts on groundwater hydrochemical cycling by causing groundwater salinization. The spatiotemporal distributions of groundwater hydrochemistry are crucial for studying groundwater salt migration, and also vital to understand hydrological and hydrogeochemical processes of groundwater in arid inland oasis areas. However, due to constraints posed by the paucity of observation data and intense human activities, these processes are not well known in the dried-up river oases of arid areas. Here, we examined spatiotemporal variations and evolution of groundwater hydrochemistry using data from 199 water samples collected in the Wei-Ku Oasis, a typical arid inland oasis in Tarim Basin of Central Asia. As findings, groundwater hydrochemistry showed a spatiotemporal dynamic, while its spatial distribution was complex. TDS and δ18O of river water in the upstream increased from west to east, whereas ion concentrations of shallow groundwater increased from northwest to southeast. Higher TDS was detected in spring for shallow groundwater and in summer for middle groundwater. Pronounced spatiotemporal heterogeneity demonstrated the impacts of geogenic, climatic, and anthropogenic conditions. For that, hydrochemical evolution of phreatic groundwater was primarily controlled by rock dominance and evaporation-crystallization process. Agricultural irrigation and drainage, land cover change, and groundwater extraction reshaped the spatiotemporal patterns of groundwater hydrochemistry. Groundwater overexploitation altered the leaking direction between the aquifers, causing the interaction between saltwater and freshwater and the deterioration of groundwater environment. These findings could provide an insight into groundwater salt migration under human activities, and hence be significant in groundwater quality management in arid inland oasis areas.

The study assesses the reliability of the description of hydrothermal conditions in the territory of Kalmykia with the use of quantitative climate indicators based on air-temperature and precipitation data that are available in databases and are widely used in climate models. The present study considers the use of the Selyaninov hydrothermal coefficient, the precipitation-evaporation coefficient, the Thornthwaite aridity index, the Koppen method, and the Holdridge scheme. Quantitative climate indicators were estimated for 1966–2017 based on data on the average monthly air temperature and total monthly precipitation at Yashkul’ weather station located in the Chernye Zemli strict nature reserve, which is the most arid part of the Republic. The estimated values of Selyaninov hydrothermal coefficient for the considered period corresponded to natural zones of deserts in two cases, semideserts in 19, and steppes in 31. With the precipitation-evaporation coefficient, the climate conditions corresponded to semidesert in 45 cases and steppe in seven. The values obtained with Thornthwaite aridity index were inherent for deserts and hyperarid regions. According to the Holdridge scheme, the hydrothermal conditions matched steppe zones in 25 cases and deserts in 27. The reliability is highest for climate assessments produced with the involvement of Selyaninov hydrothermal coefficient, which indicate humid warming in Kalmykia and are supported by material collected via the observation of plant communities that form on the ameliorated lands of Priergeninskaya Plain. The presence of humid warming is also supported by estimates based on the Koppen method, the Holdridge scheme, and, to a lesser degree, the precipitation-evaporation coefficient. The assessment involving the Thornthwaite aridity index points to an intensified climate aridization, which is not in line with the modern dynamics of climate conditions in Kalmykia and is thus not reliable.

Fire is considered a critical process for limiting shrub encroachment and maintaining grassland structure and functions. Fire can be detrimental to grasses in upland settings of arid desert grasslands, but no studies have been performed in more productive swale grasslands. Monitoring of a prescribed fire treatment in a swale grassland in southern New Mexico indicated that perennial grasses had not recovered after 5 years, even with above-average rainfall. Furthermore, indicators of erosion susceptibility increased, and shrubs resprouted rapidly.

We conducted a one-year-long study of solute load measured three times per month in three neighboring subwatersheds (Alashtar, Khorram Abad, and Biranshahr) located in the Karkheh River basin in the Zagros region of southwestern Iran. Research was focused on the chemical composition of water (solute load), karst denudation rate, spatial and temporal variability, as well as comparison of solute load with suspended load. Results show that Ca-Mg-HCO3 is the dominant water type that reflects the lithological characteristics of the catchment areas. Lack of seasonal fluctuation of solute load and absence of dilution during high water levels but evident seasonal course of discharge defines the highest solute flux during the annual maximum of discharge in spring months. The highest solute flux is related to flood events. High annual variation of Na1 concentration compared to conservative Cl2 as well as Chloro-Alkali indexes (CAI and CAI2) suggests that Na1 adsorption and desorption during ion-exchange reactions occur in the regolith. This Na+ variability, to some extent, explains weak Ca21 and Mg21 dilution effect during high water levels. During the measurement period (2014-2015), solute flux calculated per catchment area amounted to 49-69 t km-2 a-1 (tons per km per year). The chemical composition of water and discharge shows by far the highest chemical denudation of limestones and dolomites (87−89 %), while dissolution of gypsum is of minor importance (11−13 %). As a result, the carbonate karst solutional denudation rate is between 0.010 and 0.040 mm a21 , where the higher values are more probable for longer periods due to the relatively low discharge during the spring of 2015. Comparison of dissolved and suspended loads indicates that the transport of suspended load is an order of magnitude less than transport of the dissolved load; the only exception is one flash flood event when suspended load exceeded the dissolved load. Besides a small decrease in solute flux as well as carbonate karst dissolution rates from NW to SE, no large hydrochemical differences between the three subwatersheds were detected.

Relevance . An analysis of the development of feed production in the Stavropol Territory shows that at present, due to the low productivity of natural forage lands, the level of feed production does not meet the requirements for the development of animal husbandry. Illiterate anthropogenic influence in the dry-steppe regions of the region, where about 70% of the number of sheep and 30% of the number of beef cattle are located, led to the fact that up to 300 thousand hectares of hayfields and pastures were subjected to erosion and deflation. However, in recent years, the process of improving forage land has been reduced to a minimum. Therefore, the process of restoring the forage productivity of hayfields and pastures should be given close attention. To this end, in the zone of dry steppes we conducted research on the selection of perennial legumes and grasses of a new generation to create highly productive grassland agrophytocenoses of long-term use. Methods . The experiments were carried out in the conditions of arid and extremely arid zones of the Stavropol Territory. The objects of research were perennial legumes and cereals and their herb mixtures. Restoration of degraded hayfields and pastures was carried out by means of amelioration and superficial improvement. Results . According to our research, by enriching the degenerated grass with valuable legumes and cereals in terms of forage it is possible to significantly increase its productivity and quality. In extremely arid and arid zones the most effective mixtureswere ones involving 4 and 5 components, which yield reached 15.3–23.8 t/ha of green mass, and the yield of feed units per 1 ha was 1.9–2.6 t/ha. The increase in the productivity of the improved herbage had a positive effect on the feed capacity of the land, which increased to 0.83–1.30 conventional heads per 1 ha.

Soil salinization is one of the main problems hindering the agricultural development in the arid and semi-arid regions. However, many previous studies of soil salinization monitoring failed to cons...

Despite the intriguing correlation between continental flood basalt provinces and environmental crises, little is known about how the local/regional sedimentary systems and environment respond to flood basalt volcanism. Active sedimentary systems, and their interaction with volcanism, provide an important rock record to understand palaeoenvironments in volcanic settings. The Paraná–Etendeka Igneous Province is a well-known example of a continental flood basalt emplaced on a dry desert environment, but evidence has also shown the existence of humid conditions during the volcanic episode. This work describes and interprets non-volcanic sedimentary and volcaniclastic rocks interbedded with Paraná–Etendeka Igneous Province lavas in southernmost Brazil to better understand the palaeoenvironmental process and changes during the onset of volcanism. Non-volcanic sedimentary rocks record the existence of ephemeral sheet-like flows and ponds/lakes while volcaniclastic rocks document hydromagmatic activity, supporting a change to more humid conditions. Stratigraphic constraints indicate that this change started with the onset of volcanism and affected the whole province. We suggest that SO 2 degassing from the Paraná–Etendeka province may have caused a net global surface cooling, resulting in precipitation redistribution and a local increase in rainfall. This hypothesis may help explain the cooling and increased humidity observed elsewhere to be closely related to the Paraná–Etendeka emplacement.

Innovative methods are vital to protect groundwater when a nexus of factors is intermixed to control the quality, particularly in the arid industrial urban centers located in intensified agriculture. The research introduces the first insights of the hydrochemical pollution patterns, and their controlling factors focused on combined spatiotemporal statistical, P-spline modeling, and the trends identification of Mann–Kendall and Theil–Sen. Guidelines for the shallow groundwater of the Nile Delta aquifer (Egypt) were exceeded for total alkalinity, Al3+, Pb2+, Fe2+, total dissolved solids, Cd2+, Cr2+, Mn2+, Ni2+, and pH, in decreasing order. Exceedance of the allowable limit of pollutants varied considerably between districts. Among the 55 sites, major degradation patterns were identified TDS, Fe2+, total alkalinity, Al3+, pH, Zn2+, Cu2+, Cr2+, NO−3, Mn2+, Co2+, Ni2+, Cd2+, and Pb2+, in decreasing order. Deteriorations marked the heavily inhabited areas with expansive quantities of organic and inorganic contaminants and elevated heavy metal loads from industrial and domestic untreated wastewater besides the roadside emission and exhaust and from diffuse drainage flow into the dense network of drains and canals serving the agriculture. Density of roads contributed significantly to the elevated rates of Cu2+, Zn2+, Cr2+, Cd2+, Pb2+, and Fe2+, in decreasing order. Irrigation canals density controlled total alkalinity, TDS, Cu2+, and Mn2+. Density of drains strongly affected the rate, mean and maximum contents of Fe2+ and Mn2+, the mean value of Cu2+, and the mean and maximum values of Al3+.

A number of major factors have driven the volume and nature of aeolian geomorphology in the second half of the twentieth century: the growth of process studies; the availability of remote sensing, the development of new dating techniques (e.g. optical dating), the utilization of new technologies (e.g. data loggers and global positioning systems); computer modelling of dune forms, wind action and sediment movement; the recognition of the importance of aeolian forms and processes in extraterrestrial settings (especially Mars); the role of aeolian dust in atmospheric processes; the search for analogues for ancient hydrocarbon-bearing strata; the appreciation of the importance of climatic changes in desert areas; a concern with what may happen to arid environments in a warmer world; and an increasing realization that aeolian phenomena could be hazardous. This chapter does not deal with coastal dunes, but concentrates on those of the major lower-latitude drylands. It discusses the main controls on dune forms, the nature of sand seas, ancient and modern, and the nature of dune sediments. It also shows that during the 1970s there was a burgeoning interest in dust storms. In addition, with the availability of remote sensing imagery, it was possible to see for the first time that wind-furrowed yardangs were striking features with a wide global distribution. The origin of closed depressions (pans) generated a large literature, and hypotheses for their formation were put forward that included wind erosion, solution, excavation by animals, karstic and pseudo-karstic solution, and tectonic subsidence. Remote sensing showed just how important they were in drylands. Other phenomena that attracted attention and some controversy were stone pavements and peri-desert loess. Finally, it is suggested that the nature of aeolian processes and forms will be modified in a warmer world.

The work reflects the analysis of changes in the productivity of crops of crop rotation during the long-term use of fertilizer systems in a stationary experiment for the period from VI to VIII rotation (1999-2001 - 2016-2018). The influence of various doses of nitrogen, phosphorus and nitrogen-phosphorus fertilizers on the change in the content of nitrate nitrogen and mobile phosphorus in the conditions of the southern chernozem for the specified period of research was determined. The responsiveness of crop rotation crops to the application of nitrogen, phosphorus, and nitrogen-phosphorus fertilizers in minimum, medium and high doses has been established.

Net ecosystem gas exchange (NEE), a balance between gross ecosystem primary productivity (GPP) and ecosystem respiration (ER), is an important indicator of terrestrial ecosystem CO2 sink or source. Increasing frequency in droughts during different periods of the growing season may affect terrestrial ecosystem carbon (C) balance. However, detecting how drought timing controls ecosystem C processes is insufficiently explored because it is a challenge to accurately monitor and forecast drought dynamics. In a 5-year (2015–2019) precipitation manipulation experiment in a temperate steppe in northern China, we imposed a 60% decrease in precipitation in the early (April–June, DEP) and late (July–September, DLP) growing seasons in plots under rainout shelters to simulate drought occurrence timing. The responses of GPP, ER and NEE to DEP and DLP were examined to determine how the timing of decreased precipitation affects CO2 fluxes. Both DEP and DLP reduced GPP and ER. Decreased precipitation in the late growing season reduced NEE due to a greater decline in GPP than ER. In contrast, the lack of an effect of DEP on NEE can be attributed to a proportional decline in GPP and ER. Reduced normalized difference vegetation index (NDVI) and GPP induced by decreased precipitation explained the decline in GPP and ER respectively. Drought in the late growing season weakened the ecosystem C sink. The result indicates a low resistance in net C uptake to DLP. However, we did not find evidence that previous precipitation decreases resulted in a lower overall rate of ecosystem C exchange, indicating a high resilience in C processes in this semi-arid grassland. Synthesis and applications. Our study provides solid evidence that drought in the late growing season weakens ecosystem C sink in the semi-arid grassland. The findings suggest that management practices aimed at enhancing water availability during the late growing season should be preferred for increasing C sequestration.

Water use efficiency is a research topic of increasing importance, especially in arid lands. The main objective of this work is to apply parametric evaluation techniques for assessing the most suitable irrigation systems in an area of 36 km2 in the south of Bahariya Oasis of the Western Desert in Egypt using GIS. Twelve soil profiles were made to represent the different landforms of the study area. The soil physicochemical analyses were carried out and input in the Geographic Information System to produce suitability maps for irrigation methods. The results indicated that the application of drip irrigation increased the suitability of the land by 37.9% compared to sprinkler irrigation and 47.2% compared to surface irrigation. On the other hand, the application of surface irrigation reduced land suitability by 9.4% compared to sprinkler irrigation and 47.3% compared to drip irrigation. The main Limitations in using surface, and sprinkler irrigation methods are salinity , coarse texture and slope while limitations in using drip irrigation are salinity and coarse texture. Based on these results, applying the drip irrigation method in the study area is efficient and useful in improving land productivity and conservation.

To better understand the variation in mountainous discharge (MD) in the future, a basin case study was conducted in the upstream Taolai River Basin (UTRB) in arid northwestern China. The Blaney-Criddle (B-C) equation, Budyko framework, and water balance method were coupled for MD calculations. The outputs of 10 global climate models (GCMs) are synthesized to confirm the future changes in air temperature and precipitation under 3 selected Representative Concentration Pathway (RCP) scenarios. The climate elasticity (CE) method was used to determine the variation in MD, and the influence of climate factors on that was quantitatively analyzed. The results reveal that the coupling framework of the three methods is suitable for MD determination in the UTRB. The weight-based synthesis of the 10 GCM outputs shows overall increases in temperature (T) and precipitation (P) under the 3 scenarios during most of the time until 2099. The above climate change leads to an increase in MD. According to CE analysis, the positive effectiveness of precipitation is greater than the negative effectiveness of temperature on MD variation, and the increase in precipitation would induce more MD in the UTRB. Uncertainty analysis reveals that GCM outputs dominate in predicting precipitation, while the RCP scenarios influence temperature more. Overall, under the background of climate change, the risk of extreme floods during wet years might increase, and a water deficit will still occur during normal and dry years. The study provides a case example for better understanding MD responses to climate change in the upper reaches of inland river basins. Findings are helpful for reasonable water resource development and utilization in the middle and lower reaches of these basins in the future. As in the Taolai River Basin, considering the future water demand across the whole basin, the development of water-saving technologies and reasonable industrial structures is crucial for a sustainable future.

In arid and semiarid regions from the southwestern USA and vast areas of northwestern Mexico, Santa Ana wind events modify the environment with high temperatures, very low humidity, and dust storms representing a recurrent phenomenon that triggers asthma and other respiratory diseases. While research has emphasized Santa Ana wind effects on the USA side, northwestern Mexico has been less investigated. Numerical modeling of a severe dust storm in November 2018, applying the Weather Research and Forecasting model coupled with a chemistry module (WRF-Chem), revealed that erosion, transport, and dust storms extend along the peninsula and the Gulf of California. Santa Ana winds eroded large areas, transported desert conditions to urban zones, causing high dust concentrations and reducing the relative humidity below 10%, deteriorating climatic conditions favorable to wellness. In Tijuana, Mexicali, Ensenada, San Diego, and Los Angeles, PM10 and PM2.5 concentrations (particle matter with diameter below 10 µm and 2.5 µm) reached values over 2000 µg/m3 for PM10, with daily mean concentrations well above national standards, leading to poor air quality and representing a health threat even in short-term exposure. This Santa Ana event transported dust particles several hundreds of kilometers over urban areas, the Gulf of California, and the Pacific Ocean. Severe soil deterioration was simulated within the study area, reaching dust emissions above 700,000 t, including croplands from the northern part of Baja California and Sonora's coastal area.

This paper reconstructs the vegetation history of the Lake Pueyrredon area during the Holocene and contextualizes the use of space and resources by hunter-gatherer groups according to palaeoenvironmental evolution. The pollen analysis of the Los Flamencos lake sequence is presented and integrated with local archaeological pollen data. Early Holocene vegetation consisted of a dwarf-shrub-grass steppe associated with cold conditions. From 7,600 cal bp a shrub vegetation with forest patches is inferred, suggesting a high moisture availability and possibly involving an eastwards displacement of the forest-steppe ecotone boundary. Human occupation, previously interrupted by the Hudson volcano eruption, and use of space is evident in this period. Between 6,600 and 5,400 cal bp an environmental change to drier conditions suggests a heterogeneous shrub steppe and the higher availability of floristic resources possibly used by hunter-gatherer groups. The predominance of shrub steppe with dwarf shrubs from 5,400 cal bp indicates more arid than current conditions, which correlates with a higher human-environment interaction related to changes in the lake configuration allowing new north–south circulation roads and vice versa, and major floristic resources availability. A decrease in dwarf-shrubs indicates a slight increase in moisture availability since 3,550 cal bp, suggesting a weakening of the westerly winds. The results indicate local and regional changes in vegetation linked mainly to moisture availability and Southern Westerly Winds fluctuations. The integration of pollen, archaeological and palaeogeographic information available and its comparison with other fossil records studied in Patagonia complement palaeoenvironmental reconstruction and explain the changes in a regional palaeoenvironmental framework.

Continuous landscape components along the lateral riverside are affected by both hydrologic connectivity and disconnectivity. In recent years, anthropogenic activities and climate changes have caused wetland shrinkage and land degradation along the lateral riverside of many arid and semiarid regions. Since microorganisms are major drivers of soil biochemical cycling, it is essential to examine soil microbial communities along the lateral landscape continuum to understand their ecosystem functioning and predict future land changes. Here, we collected samples along a lateral riverbed center-riverbed edge-oxbow lake-floodplain-terrace continuum (i.e., landward distribution) in the Xilin River Basin, Inner Mongolia, China. The floodplain had the highest microbial diversity and heterogeneity, with Bacteroidetes, β- and γ-Proteobacteria being the most abundant taxa. In contrast, the terrace had the lowest microbial diversity and heterogeneity, with Acidobacteria, Actinobacteria, Verrucomicrobia, Gemmatimonadetes, and α-Proteobacteria as the most abundant taxa. Silt particle, salinity, and moisture were the most influential factors for landward variation of bacterial communities along the riverside continuum. Altogether, we demonstrate that dominant bacterial lineages, soil particles, and moisture-related factors are valuable indicators of this continuum, which can be leveraged for the early prediction of drought-induced wetland shrinkage and grassland desertification.

Calcium (Ca) is an essential nutrient for plant growth and Ca concentrations in forage have important implications for ruminant diet and health. It remains an open question whether forage Ca concentration would be decreased by increasing nitrogen (N) deposition. We manipulated the increasing rates of N addition (2008–2015) in a semiarid grassland, northern China. Plant Ca concentrations for all species were examined in each plot under N treatment. The Ca concentrations at functional group and community levels were calculated based on the concentration of each species presented and their relative biomass in each plot. We found that community-level Ca concentration remained stable across a gradient of wide-ranged N addition rates, although Ca concentration at both species and functional group levels showed negative responses to N enrichment. Given that forbs had higher Ca concentration than grasses, the increasing relative biomass of forbs canceled out the negative responses of species-level and functional group-level Ca concentration. Our results further showed that community Ca pool showed a positive but saturating response to N addition, with a threshold at the rate of 10 g N m−2 yr−1. Our findings highlight the role of changes in plant relative biomass in controlling the responses of forage Ca concentration and stock to N enrichment.