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The Namib Desert is characterized by a number of abiotic stresses, including high temperature, high salinity, osmotic pressure, alkaline pH, and limited water availability. In such environments, dry soils typically exhibit a low water potential, scarce nutrients, and high concentrations of dissolved ions, collectively creating a challenging habitat for microbial life. In this study, 89 bacterial isolates belonging to 20 genera were identified. Bacteria demonstrated significant osmotolerance, with some strains thriving at polyethylene glycol (PEG) concentrations exceeding 20%. Furthermore, these bacteria demonstrated halotolerance, high pH tolerance, and capacity to produce plant growth-promoting (PGP) traits under conditions of osmotic stress. Osmotolerant bacteria exhibited higher proficiency in siderophore production, potassium solubilization, and phosphorus solubilization, all of which are critical for supporting plant growth in nutrient-scarce and stressful environments, such as deserts. However, alginate production was higher in isolates that were less osmotolerant, indicating the potential for a compensatory mechanism in strains that were more sensitive. These findings highlight the complex strategies employed by desert bacteria to survive and support host plants in extreme environments. The present study not only enhances our understanding of microbial adaptations in arid ecosystems, but also provides important information for the development of potential applications for these bacteria in the reclamation of arid land and agricultural practices aimed at improving crop resilience to abiotic stress. [ABSTRACT FROM AUTHOR]

Inspired by the back of Namib Desert beetle, 1T-MoS 2 -based aerogel beads enabled harvest water from atmospheric humidity and sustainable freshwater generation from soil, which could alleviate the water shortage in harsh environments. [Display omitted] Freshwater scarcity is one of the most critical issues worldwide, particularly in arid regions, stemming from population growth and climate change. Inspired by the hydrophilic bump structures of desert beetles, 1T-MoS 2 -based aerogel beads with porous structures and CaCl 2- crystal loading (termed as MoAB-m@CaCl 2 -n) were prepared for freshwater harvesting. Metallic-phase MoS 2 nanospheres exhibit excellent photothermal conversion abilities, facilitating solar-driven water desorption and evaporation. Owing to the synergistic effect of its localized surface features, hydrophilic groups, and dispersive CaCl 2 particles, MoAB-2@CaCl 2 -2 efficiently harvests water from atmosphere with a superior moisture adsorption capacity (0.18–0.82 g g−1) at a wide range of relative humidity (10 %-70 %). Under one-sun illumination, MoAB-2@CaCl 2 -2 demonstrates an outstanding solar-driven water evaporation rate of 2.25 kg m-2h−1. The water evaporation rate from soil (water content = 20 %) is 1.19 kg m-2h−1, which is sufficient for sustainable freshwater generation from the soil in arid regions. More importantly, the multifunctional MoAB-2@CaCl 2 -2-based homemade freshwater generation prototype delivers a certain amount of water harvesting (0.99 g g−1 day−1) on a rainy day and provides an impressive daily freshwater yield (53.7 kg m−2) under natural sunlight. The integrated device exhibits excellent efficiency and practicality and offers a feasible method for freshwater harvesting in harsh environments. [ABSTRACT FROM AUTHOR]

This document discusses the challenges faced by plants in arid and semi-arid regions due to harsh environmental conditions such as limited rainfall, high temperatures, and poor soil nutrition. The document highlights the importance of understanding plant adaptation strategies to extreme environments in order to protect and manage local vegetation and ecosystems. The document presents research papers that cover various aspects of plant adaptation in arid regions, including water uptake mechanisms, physiological and biochemical adaptations, plant-soil microbial interactions, and ecosystem services. The research findings provide insights into how plants in arid regions adapt to environmental changes and maintain ecological balance. However, further research is needed to fully understand the processes and mechanisms of plant adaptation in extreme environments. [Extracted from the article]

Cyanobacteria inhabit extreme environments, including drylands, providing multiple benefits to the ecosystem. Soil degradation in warm drylands is increasing due to land use intensification. Restoration methods adapted to the extreme stress in drylands are being developed, such as cyanobacteria inoculation to recover biocrusts. For this type of restoration method to be a success, it is crucial to optimize the survival of inoculated cyanobacteria in the field. One strategy is to harden them to be acclimated to stressful conditions after laboratory culturing. Here, we analyzed the genome and ecophysiological response to osmotic desiccation and UVR stresses of an Antarctic cyanobacterium, Stenomitos frigidus ULC029, which is closely related to other cyanobacteria from warm and cold dryland soils. Chlorophyll a concentrations showed that preculturing ULC029 under moderate osmotic stress improved its survival during an assay of desiccation plus rehydration under UVR. Additionally, its sequential exposure to these stress factors increased the production of exopolysaccharides, carotenoids, and scytonemin. Desiccation, but not osmotic stress, increased the concentrations of the osmoprotectants trehalose and sucrose. However, osmotic stress might induce the production of other osmoprotectants, for which the complete pathways were observed in the ULC029 genome. In total, 140 genes known to be involved in stress resistance were annotated. Here, we confirm that the sequential application of moderate osmotic stress and dehydration could improve cyanobacterial hardening for soil restoration by inducing several resistance mechanisms. We provide a high‐quality genome of ULC029 and a description of the main resistance mechanisms (i.e., production of exopolysaccharides, osmoprotectants, chlorophyll, and carotenoids; DNA repair; and oxidative stress protection). [ABSTRACT FROM AUTHOR]

The Saladas de Sástago-Bujaraloz is an endorheic and arheic complex of lagoons located in the Ebro Basin and protected by the Ramsar Convention on Wetlands. Due to the semi-arid climate of the region and the high salinity of their waters, these lagoons constitute an extreme environment. We surveyed the biodiversity of salt-tolerant and halophilic fungi residents of the Laguna de Pito, a lagoon belonging to this complex. Therefore, we collected several samples of water, sediments, and soil of the periphery. Throughout the study, we isolated 21 fungal species, including a strain morphologically related to the family Microascaceae. However, this strain did not morphologically match any of genera within this family. After an in-depth morphological characterization and phylogenetic analysis using a concatenated sequence dataset of four phylogenetically informative molecular markers (the internal transcribed spacer region (ITS) of the nuclear ribosomal DNA (nrDNA); the D1-D2 domains of the 28S gene of the nuclear ribosomal RNA (LSU); and a fragment of the translation elongation factor 1-alpha (EF-1α) and the β-tubulin (tub2) genes), we established the new genus Dactyliodendromyces, with Dactyliodendromyces holomorphus as its species. Additionally, as a result of our taxonomic study, we reclassified the paraphyletic genus Wardomyces into three different genera: Wardomyces sensu stricto, Parawardomyces gen. nov., and Pseudowardomyces gen. nov., with Parawardomyces ovalis (formerly Wardomyces ovalis) and Pseudowardomyces humicola (formerly Wardomyces humicola) as the type species of their respective genera. Furthermore, we propose new combinations, including Parawardomyces giganteus (formerly Wardomyces giganteus) and Pseudowardomyces pulvinatus (formerly Wardomyces pulvinatus). [ABSTRACT FROM AUTHOR]

In drylands, where resources are scarce, wild edible plant (WEP) knowledge is crucial to overcome food scarcity. Understanding the distribution pattern of local ecological knowledge (LEK) about WEP and identifying knowledge holders are key steps to assessing the resilience and vulnerability of knowledge systems. However, little is known about how WEP knowledge is distributed across life stages and gender of people living in arid regions. Here, we study the distribution of WEP knowledge within a small-scale society from southwestern Madagascar, a region known for its dry climate and related food crises. We worked with Tanalana male and female children and adults using semi-structured interviews and free listings. Tanalana people display a sophisticated LEK adapted to the extreme environment in which they live, with a distinct distribution pattern regarding theoretical and practical knowledge across life stages and gender. While women and men cited similar WEP, children and adults cited different sets of WEP, suggesting they hold differentiated bodies of theoretical knowledge, however our results suggest similarity in practical knowledge across life-stage and gender. We argue that resource limitation and food scarcity might be so pervasive in the area that extensive sharing of knowledge on WEP could be an adaptation to the extremely dry environment. [ABSTRACT FROM AUTHOR]

The changes of soil moisture, salinity, and nutrients by halophyte colonization in high-salinity environment profoundly affect the assembly and structure of microbial communities. However, salt marshes in arid region have received little attention. This study was conducted in Lianhuachi Lake, a typical inland salt marsh wetland in China, to determine the physicochemical characteristics of salt crusts in [Kalidium cuspidatum (Ung.-Sternb.) Grub.] colonization areas and bulk soil, respectively, and to analyze the microbial community structure of salt crusts by high-throughput sequencing. Kalidium cuspidatum colonization significantly decreased total salinity, soil water content, and water-soluble ions of salt crusts and increased total carbon, total nitrogen, and total phosphorus content. At the same time, changes in physicochemical properties caused by Kalidium cuspidatum colonization affect the ecological processes of bacterial, fungal, and archaeal community assemblies in salt crusts. In addition, cross-kingdom network analysis showed that Kalidium cuspidatum colonization increased the complexity and stability of microbial networks in salt crust soils. Functional projections further showed that bacterial diversity had a potential driving effect on the nitrogen cycle function of salt crust. Our study further demonstrated the different ecological strategies of microorganisms for halophyte colonization in extreme environments and contributed to the understanding of restoration and management of salt marsh wetlands in arid region. [ABSTRACT FROM AUTHOR]

As arid lands expand across the globe, scholars increasingly turn to the archaeological record for examples of sustainable farming in extreme environments. The arid north coast of Peru was the setting of early and intensive irrigation-based farming; it is also periodically impacted by sudden, heavy rainfall related to the El Niño Southern Oscillation (ENSO) phenomenon. While the sociopolitical effects, technologies, and engineering expertise of these irrigation systems have been thoroughly examined and theorized, little is known about how farmers managed periods of water stress. The aim of this study is to test whether arid zone farming was supported by hybrid, intermittent flood and perennial water source systems in the prehispanic past. An arroyo in the Chicama Valley was selected for preliminary data collection, and these data are presented here: (1) drone photography of the arroyo capturing the aftermath of a recent (2023) rain event; and (2) potassium (K) soil test kit results from samples collected near suspected prehispanic check dam features in the same area. The paper combines these data with comparative examples from the literature to suggest that the prehispanic features functioned as water-harvesting infrastructure. The paper concludes that sustainable, arid zone farming can be supported by hybrid, intermittent flood and perennial water source systems. [ABSTRACT FROM AUTHOR]

Although extreme El Niño events (EENEs) have always impacted hydrological anomalies and sediment transport in South America, their intensification by global warming and their association with changes in human activities and land cover after humid periods may lead to the acceleration of sediment transfers in river systems and dam reservoirs. This situation may threaten soil and water resources in arid and semiarid regions highly dependent on water originating from large dams. In this study, we investigated the sediment sequence accumulated in the Poechos Reservoir (northern Peru) and provided a retrospective reconstruction of the interactions of El Niño–Southern Oscillation (ENSO), agricultural practices and vegetation cover changes with sediment dynamics (1978–2019). To this end, a sediment core was dated and characterized by physical and chemical analyses (e.g., scanner tomography, X-ray fluorescence, particle size analysis) to estimate the evolution of sedimentation rates and changes in sediment sources during the last 5 decades. Sediment tracing results indicated the occurrence of changes in sediment sources associated with positive and negative phases of the Eastern Pacific index with a greater contribution of the lowland dry-forest area in comparison to that of the Andean area to sediment during the El Niño events (mean contribution of 76 %; up to 90 % during the coastal El Niño events (CENEs) of 2016–2017). This source contribution was mostly controlled by the stationary rainfall occurring during the EENEs in the lowland dry-forest area characterized by a low vegetation cover. Overall, after an extreme phase of ENSO, like after the EENE 1982–1983, the normal discharges and persistent sediment supplies from the middle- and upper-catchment parts led to river aggradation and the storage of substantial amounts of sediment in alluvial plains. In the absence of a significant EENE between 1983 and 1997, the large volume of sediment stored in the alluvial plains was exported by the EENE 1997–1998 resulting in an increase in sedimentation rate of 140 % after 1997 with a significant aggradation of the deltaic zone of the reservoir. In addition to the impact of extreme climate events on sediment dynamics, the development of agriculture along the riverine system after an extreme phase of ENSO increased the availability of sediments in the main channel of the rivers, easily transported by the next EENE. This study suggests that intensification of human activities associated with a higher frequency of extreme rainfall events amplified the quantity of sediment transported by the river system, which will significantly decrease the lifespan of the reservoir, which is essential to meeting the freshwater demands of the farmers and the populations living in this arid and semiarid region. [ABSTRACT FROM AUTHOR]

Saline and hypersaline waters are one of the most peculiar ecosystems of our planet, characterized by extreme life conditions. Despite their worldwide distribution, the diversity and abundance of protist communities in these ecosystems remain poorly studied. Here, we analyze planktonic communities of protists sampled across 38 saline and hypersaline water environments (2–390‰) from arid climatic zones of the South Urals and Crimea in light of environmental data using high-throughput 18S rDNA amplicon sequencing. A total of 9 eukaryotic supergroups, 34 phyla, 104 classes, 184 orders, 315 families and 548 genera have been identified. We revealed significant differences in the taxonomic structure of protist communities depending on salinity, geographic location and pH. The protist communities demonstrated linear regression of richness and diversity and growth of the percentage of unclassified Eukaryota (up to 43%) with the increase in salinity. Centrohelids demonstrated the ability to inhabit a broad range of salinities, up to 320‰, which is four times higher than previously reported. Centrohelid species Pinjata ruminata and Yogsothoth sp. are assumed to be specifically adapted to salinity of 3–210‰. The obtained results provide insight into the taxonomy and diversity of protists in saline and hypersaline environments and highlight the great potential for the discovery of new taxa due to the large number of unclassified 18S rDNA sequences. [ABSTRACT FROM AUTHOR]

Rapid learning in the young of most endothermic animals can be expected to be favored by natural selection because early independence reduces the period of vulnerability. Cases of comparatively slow juvenile development continue, therefore, to attract scientific attention. In most species of birds, including raptors, the young depend on their parents for some time after fledging for the provisioning of food and for protection while they learn to become nutritionally and otherwise independent. Among raptors, post-fledging dependence periods that exceed 6 months are exclusive to the largest species and these have reproductive cycles that exceed 12 months. By contrast, young of the medium-sized grey falcon Falco hypoleucos have been reported in close company with their parents up to 12 months after fledging, that is, at a time when the adults are expected to breed again. We investigated the occurrence and characteristics of prolonged adult–juvenile association relative to other falcons and similar-sized raptors. We found that the behavioral development of grey falcon young is extremely delayed, and that they even depend nutritionally on their parents for up to 12 months after fledging. We suggest that these 2 distinctive features are, ultimately, adaptations of the grey falcon to its extreme environment, Australia's arid and semi-arid zone, one of the hottest environments in the world. [ABSTRACT FROM AUTHOR]

Archaea represent a diverse group of microorganisms often associated with extreme environments. However, an integrated understanding of biogeographical patterns of the specialist Haloarchaea and the potential generalist ammonia‐oxidizing archaea (AOA) across large‐scale environmental gradients remains limited. We hypothesize that niche differentiation determines their distinct distributions along environmental gradients. To test the hypothesis, we use a continental‐scale research network including 173 dryland sites across northern China. Our results demonstrate that Haloarchaea and AOA dominate topsoil archaeal communities. As hypothesized, Haloarchaea and AOA show strong niche differentiation associated with two ecosystem types mainly found in China's drylands (i.e. deserts vs. grasslands), and they differ in the degree of habitat specialization. The relative abundance and richness of Haloarchaea are higher in deserts due to specialization to relatively high soil salinity and extreme climates, while those of AOA are greater in grassland soils. Our results further indicate a divergence in ecological processes underlying the segregated distributions of Haloarchaea and AOA. Haloarchaea are governed primarily by environmental‐based processes while the more generalist AOA are assembled mostly via spatial‐based processes. Our findings add to existing knowledge of large‐scale biogeography of topsoil archaea, advancing our predictive understanding on changes in topsoil archaeal communities in a drier world. [ABSTRACT FROM AUTHOR]

The global hydrological cycle is predicted to be intensified under the warming climate, with more extreme precipitation events and longer dry spell in between. Here, we evaluated how extreme precipitation events (EPEs) with antecedent dry (dry-EPEs) and wet (wet-EPEs) water conditions influence carbon exchange along gradient of arid, semi-arid, and sub-humid ecosystems based on eddy covariance datasets. After EPEs, ecosystem respiration and gross primary productivity (GPP) were stimulated by pulses of soil moisture in arid and semi-arid regions, but suppressed by decreased soil temperature in sub-humid region. Antecedent water condition determined asynchronous response of ecosystem respiration and GPP to EPEs, and therefore fluctuations in net carbon balance. Net carbon uptake capacity was enhanced immediately following wet-EPEs because of more rapid and greater response of GPP than respiration. However, after dry-EPEs, net carbon uptake capacity decreased immediately and increased thereafter because the response of GPP to dry-EPEs lagged behind ecosystem respiration. More antecedent precipitation further stimulated accumulative net carbon uptake. In general, the accumulated net carbon uptake within 3 weeks after wet-EPEs was two times and seven times of that after dry-EPEs in arid and semi-arid region, respectively. In sub-humid region, ecosystems acted as a carbon sink after wet-EPEs, but as a carbon source after dry-EPEs. We conclude that antecedent water conditions and local climate regimes need to be considered when interpreting the response of carbon exchange to EPEs in dryland ecosystems. [ABSTRACT FROM AUTHOR]

[Display omitted] • Relative humidity is the dominant climatic factor promoting soiling in arid zones. • The presence of both hygroscopic minerals in dust and humidity favor dust settling. • Wind speed contributes to clean solar glasses only when humidity is below than 20% • The area occupied by dust affects the transmittance loss more than the load of dust. Because of the massive increment in solar plants located in extreme environments, studying the association of climate parameters and soiling in natural conditions has been necessary. In this work, solar glass coupons were exposed to environmental conditions in Salvador solar plant, in the Atacama Desert, during summer and winter campaigns. The soiling was quantified and characterized, and the degradation of optical properties of soiled coupons was also measured. Regarding the reduction of the optical properties of the glass coupons, it was observed that the detrimental effect was higher in summer than in winter. A statical analysis found that this difference in soiling performance is related to the relative humidity and wind speed present in each campaign, mainly due to the daily variations of these parameters. Prolonged periods of relative humidity close to 30% promote the adhesion of particles to the PV glass surface and inhibit their resuspension by the action of the wind, i.e., more dust mass accumulates. Since the effect of soiling is more critical during the summer period, the use of a preventing soiling mitigation system is highly encouraged, and the adjustment of the cleaning schedule according to the seasonality of soiling. [ABSTRACT FROM AUTHOR]

Cyanobacteria are crucial primary producers in soil and soil crusts. However, their biodiversity in these habitats remains poorly understood, especially in the tropical and polar regions. We employed whole genome sequencing, morphology, and ecology to describe a novel cyanobacterial genus Argonema isolated from Antarctica. Extreme environments are renowned for their relatively high number of endemic species, but whether cyanobacteria are endemic or not is open to much current debate. To determine if a cyanobacterial lineage is endemic is a time consuming, elaborate, and expensive global sampling effort. Thus, we propose an approach that will help to overcome the limits of the sampling effort and better understand the global distribution of cyanobacterial clades. We employed a Sequencing Read Archive, which provides a rich source of data from thousands of environmental samples. We developed a framework for a characterization of the global distribution of any microbial species using Sequencing Read Archive. Using this approach, we found that Argonema is actually cosmopolitan in arid regions. It provides further evidence that endemic microbial taxa are likely to be much rarer than expected. [ABSTRACT FROM AUTHOR]

The evolution of Australia's distinctive marsupial fauna has long been linked to the onset of continent-wide aridity. However, how this profound climate change event affected the diversification of extant lineages is still hotly debated. Here, we assemble a DNA sequence dataset of Macropodoidea—the clade comprising kangaroos and their relatives—that incorporates a complete mitogenome for the Desert 'rat-kangaroo', Caloprymnus campestris. This enigmatic species went extinct nearly 90 years ago and is known from a handful of museum specimens. Caloprymnus is significant because it was the only macropodoid restricted to extreme desert environments, and therefore calibrates the group's specialisation for increasingly arid conditions. Our robustly supported phylogenies nest Caloprymnus amongst the bettongs Aepyprymnus and Bettongia. Dated ancestral range estimations further reveal that the Caloprymnus-Bettongia lineage originated in nascent xeric settings during the middle to late Miocene, ~ 12 million years ago (Ma), but subsequently radiated into fragmenting mesic habitats after the Pliocene to mid-Pleistocene. This timeframe parallels the ancestral divergences of kangaroos in woodlands and forests, but predates their adaptive dispersal into proliferating dry shrublands and grasslands from the late Miocene to mid-Pleistocene, after ~ 7 Ma. We thus demonstrate that protracted changes in both climate and vegetation likely staged the emergence of modern arid zone macropodoids. [ABSTRACT FROM AUTHOR]

Luo and Gong [[9]] investigated the diversity of desert shrub communities and evaluated the relationship between species diversity indexes and key climatic variables across 29 sites in Xinjiang, northwestern China. Liu et al. [[11]] explored the scale effects of the biodiversity-ecosystem multifunctionality relationship of representative desert plant communities in the southern margin of the Taklimakan Desert. Arid and semi-arid lands cover more than one-third of the earth's terrestrial area and are typically characterized by rainfall scarcity, higher temperatures and evapotranspiration, salinization, nutrient-poor soil, and a paucity of vegetation cover. [Extracted from the article]

Although sickness behaviour in response to non-lethal parasites has been documented in wild animals, it remains unclear how social and environmental stress might also shape an animal's behavioural response to parasitism, nor do we know whether simultaneous infection with more than one parasite changes the way animals respond. Here, we combine physiological, environmental, behavioural and parasite measures to investigate behavioural responses to infection in wild vervet monkeys (Chlorocebus pygerythrus) living in a semi-arid region of South Africa. We quantified both activity budget and behavioural predictability to investigate the occurrence of sickness behaviour and infection with two non-lethal gastrointestinal parasite genera. Higher parasite load was linked to an increase in the time spent resting. However, the nature of the relationship with other behaviours was contingent on both the parasite genus in question and parasite species interacted, highlighting the importance of considering co-infection. Overall, food availability was the dominant predictor of behavioural change suggesting that, for monkeys living in a more extreme environment, coping with ecological stress may override the ability to modulate behaviour in response to other physiological stressors. Our findings provide insight into how animals living in harsh environments find ways to cope with parasite infection, avoidance and transmission. Significance statement: Sickness behaviour is a suite of behaviours that occur in response to infection that may serve as an adaptive response to cope with infection. For wild animals, the ability to express sickness behaviour will be modulated by the presence of other competing stressors. Hence, the patterns shown are likely to be more complex than under captive conditions, which is where most of our knowledge of sickness behaviour comes from. Using physiological, environmental, behavioural and parasite measures, we demonstrate that although vervet monkeys (Chlorocebus pygerythrus) living in a semi-arid region of South Africa do exhibit sickness behaviours, this is contingent on the parasite genus in question. Further, food availability was the dominant predictor of behavioural change suggesting that, for monkeys living in a more extreme environment, coping with severe ecological stress may override the ability to express sickness behaviour in an adaptive fashion. [ABSTRACT FROM AUTHOR]

Biological soil crusts (BSCs) are found in drylands, cover ∼12% of the Earth's surface in arid and semi-arid lands and their destruction is considered an important promoter of desertification. These crusts are formed by the adhesion of soil particles to polysaccharides excreted mostly by filamentous cyanobacteria, which are the pioneers and main primary producers in BSCs. Desert BSCs survive in one of the harshest environments on Earth, and are exposed to daily fluctuations of extreme conditions. The cyanobacteria inhabiting these habitats must precisely read the changing conditions and predict, for example, the forthcoming desiccation. Moreover, they evolved a comprehensive regulation of multiple adaptation strategies to enhance their stress tolerance. Here, we focus on what distinguishes cyanobacteria able to revive after dehydration from those that cannot. While important progress has been made in our understanding of physiological, biochemical and omics aspects, clarification of the sensing, signal transduction and responses enabling desiccation tolerance are just emerging. We plot the trajectory of current research and open questions ranging from general strategies and regulatory adaptations in the hydration/desiccation cycle, to recent advances in our understanding of photosynthetic adaptation. The acquired knowledge provides new insights to mitigate desertification and improve plant productivity under drought conditions. [ABSTRACT FROM AUTHOR]

Desert locusts are notorious for their widespread distribution and strong destructive power. Their influence extends from the vast arid and semiarid regions of western Africa to northwestern India. Large-scale locust outbreaks can have devastating consequences for food security, and their social impact may be long-lasting. Climate change has increased the uncertainty of desert locust outbreaks, and predicting suitable habitats for this species under climate change scenarios will help humans deal with the potential threat of locust outbreaks. By comprehensively considering climate, soil, and terrain variables, the maximum entropy (MaxEnt) model was used to predict the potential habitats of solitary desert locusts in the 2050s and 2070s under the four shared socioeconomic pathways (SSP126, SSP245, SSP370, and SSP585) in the CMIP6 model. The modeling results show that the average area under the curve (AUC) and true skill statistic (TSS) reached 0.908 ± 0.002 and 0.701, respectively, indicating that the MaxEnt model performed extremely well and provided outstanding prediction results. The prediction results indicate that climate change will have an impact on the distribution of the potential habitat of solitary desert locusts. With the increase in radiative forcing overtime, the suitable areas for desert locusts will continue to contract, especially in the 2070s under the SSP585 scenario, and the moderately and highly suitable areas will decrease by 0.88 × 106 km2 and 1.55 × 106 km2, respectively. Although the potentially suitable area for desert locusts is contracting, the future threat posed by the desert locust to agricultural production and food security cannot be underestimated, given the combination of maintained breeding areas, frequent extreme weather events, pressure from population growth, and volatile sociopolitical environments. In conclusion, methods such as monitoring and early warning, financial support, regional cooperation, and scientific prevention and control of desert locust plagues should be further implemented. [ABSTRACT FROM AUTHOR]

In an era of rapid climate change and expansion of desertification, the extremely harsh conditions of drylands are a true challenge for microbial life. Under drought conditions, where most life forms cannot survive, rocks represent the main refuge for life. Indeed, the endolithic habitat provides thermal buffering, physical stability, and protection against incident ultraviolet (UV) radiation and solar radiation and, to some extent, ensures water retention to microorganisms. The study of these highly specialized extreme-tolerant and extremophiles may provide tools for understanding microbial interactions and processes that allow them to keep their metabolic machinery active under conditions of dryness and oligotrophy that are typically incompatible with active life, up to the dry limits for life. Despite lithobiontic communities being studied all over the world, a comprehensive understanding of their ecology, evolution, and adaptation is still nascent. Herein, we survey the fungal component of these microbial ecosystems. We first provide an overview of the main defined groups (i.e., lichen-forming fungi, black fungi, and yeasts) of the most known and studied Antarctic endolithic communities that are almost the only life forms ensuring ecosystem functionality in the ice-free areas of the continent. For each group, we discuss their main traits and their diversity. Then, we focus on the fungal taxonomy and ecology of other worldwide endolithic communities. Finally, we highlight the utmost importance of a global rock survey in order to have a comprehensive view of the diversity, distribution, and functionality of these fungi in drylands, to obtain tools in desert area management, and as early alarm systems to climate change. [ABSTRACT FROM AUTHOR]

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The Grey Falcon (Falco hypoleucos) is a desert-living species restricted to the dry centre of Australia. These falcons have a number of unique life-history adaptations that may be crucial for their survival in this harsh environment, but these may, conversely, confine them to these arid regions. In this study we investigated what Grey Falcon feather structure can reveal about the ecology of the species. Specifically, we tested UV reflectance and structural waterproofing of Grey Falcon feathers, and compared these properties across other Australian Falco species. Grey Falcon feathers did not reflect unique UV peaks, nor show any significant difference in structural waterproofing when compared with closely-related sympatric falcon species. This suggests that Grey Falcon feathers have no specific adaptations to prevent the impact of UV or water on their plumage, so feather structure evidently does not help explain the persistence of this species in arid Australia. We suggest that an exploration of the physiological and behavioural thermoregulatory capabilities of this species should provide further insights in understanding how these birds cope with their extreme environment and are confined there. [ABSTRACT FROM AUTHOR]

Aims: The survival and distribution of plant species in the extreme environmental conditions of semi-arid regions is strongly dependent on traits associated with drought resistance. Seed weight may be particularly important, since larger seeds are predicted to promote survival in harsh environments, especially those of low soil moisture. Here, we test this hypothesis using data on the seed weight of 277 woody plant species in the semi-arid Caatinga biome of northeast Brazil. Methods: We used Structural Equation Models (SEM) to test for associations between seed weight and biophysical conditions, including temperature, precipitation, climatic seasonality, soil-vegetation interaction and soil compaction. Results: Species occurrence data were geographically biased due to large areas of the biome that remain under-collected. The strongest statistical association was between seed weight and soil compaction, with mean temperature of the driest quarter and aridity directly influencing soil compaction (and indirectly influencing seed weight). Conclusions: We conclude that the larger seeds of woody species in the Caatinga are primarily an adaptation to compacted soil, uneven distribution of rainfall and high temperatures, intrinsic conditions of the Caatinga biome. [ABSTRACT FROM AUTHOR]

The ecological history of rangelands is often presented as a tale of devastation, where fragile drylands are irreversibly degraded through inappropriate land use. However, there is confusion about how to recognize and measure degradation, especially in low-productivity environments characterized by extreme natural variability and where abrupt and comprehensive management upheavals preclude benchmarks. These issues have important consequences for rangeland management programs, which are typically founded on presumptions of substantial and ongoing degradation from former "natural" states. We explore complementary approaches to critically assess degradation: the historical record, long-term grazing exclosures, surveys for potentially rare and sensitive plant species, and assessment of water-remote areas in relation to rare plant occurrence. Employing these approaches in inland Australia, we show that prevailing paradigms have become entrenched despite being inconsistent with empirical evidence. Our methodology can be applied to drylands with abrupt changes in management and contentious ecological narratives. [ABSTRACT FROM AUTHOR]

Extreme environmental conditions that occur in Arctic, Antarctic, high mountains, extremely arid regions, as well as in toxic or nutrient-poor substrates, shallow waters, under intense anthropogenic impact, and in specific atmosphere or its absence in extraterrestrial systems, lead to the formation of soils and soloids (soil-like bodies) that cannot be adequately described, and their genesis and geography cannot be satisfactorily explained within the framework of the traditional Dokuchaev's pedology. A new scientific direction is proposed—extreme pedology (genesis and geography of soils in extreme environments), which requires its own theory, conceptual apparatus, and methodological basis. It is based on the assumption that soils and soloids can develop in extreme conditions under the deficit or surplus of resources. In the first case, soloids are just few millimeters thick; in the second case, they have the profiles of multimeter scale. Various classes of soils and soloids extremeness are specified: factorial, regime-functional, and chorological (extra-areal). The behavior of extreme objects in time and the nature of their pedogenic records can have both specific and common features with normal soils. Morphological and analytical study of soils and soloids of extreme environments requires state-of-the-art methodological approaches and scientific equipment. [ABSTRACT FROM AUTHOR]

Abstract: Aim: Assess climatic risk to vegetation types associated with tropical and temperate ecosystems based on exposure analysis, which models future risk as a function of deviation from current climate variable distributions. Location: Oaxaca State, Mexico. Taxon: Broadly defined vegetation types used in state‐ and national‐level vegetation classification systems. These types can be grouped into series representing dry‐to‐wet conditions for tropical and temperate vegetation. Methods: We used climate exposure analysis to compare current and future climate parameters for the major vegetation types of Oaxaca. This technique integrates a recent vegetation map with historical climate data (1981–2010) to produce a baseline climate layer that is compared to climate projections made with five different global circulation models for near‐future (2015–2039) and end‐century (2075–2099) periods using two emissions scenarios (RCP 4.5 and 8.5). We classified the frequency distribution of the baseline climate into five exposure classes where the closer values are to mean climate conditions, the lower the exposure. Future exposure was estimated by classifying the vegetation pixels into the same exposure classes, now based on future climate values. Increased exposure risk was assessed based on the fraction of pixels that moved into higher exposure classes from one period to another. Results and main conclusions: Our analysis showed four general trends: (a) the higher, current track emissions scenario produced much larger end‐century climate exposure; (b) for the tropical vegetation series, tropical evergreen forests are projected as most exposed by end‐century; (c) for the temperate vegetation series the matorral‐shrubland and conifer forests are the most impacted; and (d) the five GCMs considered showed some convergence in their end‐century climate exposure predictions, with coastal and low‐elevation areas of the State projected to experience the greatest exposure, and the interior mountain slopes and central region projected to experience the least exposure and be the most climatically stable. [ABSTRACT FROM AUTHOR]

The sustainable use of ecosystem services (ES) can contribute to enhancing human well-being. Understanding the effects of land use and climate change on ES can provide scientific and targeted guidance for the sustainable use of ES. The objective of this study was to reveal the way in which land use and climate change influence the spatial and temporal variations of ES in the mountain-oasis-desert system (MODS). In this study, we assessed water yield, soil conservation, crop production, and sand fixation in 1990, 2000, and 2010 in Altay Prefecture, which is representative of the MODS, based on widely used biophysical models. Moreover, we analyzed the effects of different land use and climate change conditions on ES. The results show that the area of forest and bare land decreased in Altay Prefecture. In contrast, the area of grassland with low coverage and cropland increased. The climate of this area presented an overall warming-wetting trend, with warming-drying and cooling-wetting phenomena in some areas. Soil conservation in the mountain zone, water yield in the oasis zone, and sand fixation in the desert zone all decreased under the influence of land use change alone. The warming-drying trend led to decreased water yield in the oasis zone and increased wind erosion in the desert zone. Based on the results, we recommend that local governments achieve sustainable use of ES by planting grasslands with high coverage in the oasis zone, increasing investment in agricultural science and technology, and establishing protected areas in the mountain and desert zones. The methodology in our study can also be applied to other regions with a MODS structure. [ABSTRACT FROM AUTHOR]

In this study, we intercompare seven different PBL schemes in WRF in the United Arab Emirates (UAE) and we assess their impact on the performance of the simulations. The study covered five fog events reported in 2014 at Abu Dhabi International Airport. The analysis of Synoptic conditions indicated that during all examined events, the UAE was under a high geopotential pressure and light wind that does not exceed 7 m/s at 850 hPa (~ 1.5 km). Seven PBL schemes, namely, Yonsei University (YSU), Mellor-Yamada-Janjic (MYJ), Moller-Yamada Nakanishi and Niino (MYNN) level 2.5, Quasi-Normal Scale Elimination (QNSE-EDMF), Asymmetric Convective Model (ACM2), Grenier-Bretherton-McCaa (GBM) and MYNN level 3 were tested. In situ observations used in the model's assessment included radiosonde data from the Abu Dhabi International Airport and surface measurements of relative humidity (RH), dew point temperature, wind speed, and temperature profiles. Overall, all the tested PBL schemes showed comparable skills with relatively higher performance with the QNSE scheme. The average RH Root Mean Square Error (RMSE) and BIAS for all PBLs were 15.75% and − 9.07%, respectively, whereas the obtained RMSE and BIAS when QNSE was used were 14.65% and − 6.3% respectively. Comparable skills were obtained for the rest of the variables. Local PBL schemes showed better performance than non-local schemes. Discrepancies between simulated and observed values were higher at the surface level compared to high altitude values. The sensitivity to lead time showed that best simulation performances were obtained when the lead time varies between 12 and 18 h. In addition, the results of the simulations show that better performance is obtained when the starting condition is dry. [ABSTRACT FROM AUTHOR]

Growth in the publication of scientific articles is occurring at an exponential rate, prompting a growing need to synthesise information in a timely manner to combat urgent environmental problems and guide future research. Here, we undertake a topic analysis of dryland literature over the last 75 years (8218 articles) to identify areas in arid ecology that are well studied and topics that are emerging. Four topics—wetlands, mammal ecology, litter decomposition and spatial modelling, were identified as ‘hot topics’ that showed higher than average growth in publications from 1940 to 2015. Five topics—remote sensing, climate, habitat and spatial, agriculture and soils-microbes, were identified as ‘cold topics’, with lower than average growth over the survey period, but higher than average numbers of publications. Topics in arid ecology clustered into seven broad groups on word-based similarity. These groups ranged from mammal ecology and population genetics, broad-scale management and ecosystem modelling, plant ecology, agriculture and ecophysiology, to populations and paleoclimate. These patterns may reflect trends in the field of ecology more broadly. We also identified two broad research gaps in arid ecology: population genetics, and habitat and spatial research. Collaborations between population genetics and ecologists and investigations of ecological processes across spatial scales would contribute profitably to the advancement of arid ecology and to ecology more broadly. [ABSTRACT FROM AUTHOR]

Drought evolutions in the arid region of northwestern China from 1960 to 2010 were analyzed based on the standardized precipitation index ( SPI), the standardized precipitation-evapotranspiration index ( SPEI), and the self-calibrated Palmer drought severity index ( SC- PDSI). All three forms of drought indices were significantly correlated with each other. No statistically significant differences were found for the severity of drought, as assessed by both the SPI and SPEI. The SC-PDSI was generally an index representing water deficits at a medium period. For the entire geographical area of study, wet conditions dominated during 1987-2010, whereas persistent drought conditions occurred from 1960 to 1986. [ABSTRACT FROM AUTHOR]

Seasonal variations of soil water content over 16 months at three typical sites of the Qilian Mountain were investigated to understand the controlling factors in regulating soil moisture content and dynamics. In this study, we quantified soil moisture response to cumulative rainfall events and freezing and thawing processes. The significant response depth of soil moisture after rainfall was 0-40 cm, and the forms of effective rainfall in this semiarid region: consecutive, with small dry intervals, and a few small rainfall events, with the cumulative amount of no less than 18.5 mm. Not only vegetation but also topography and soil texture were the primary controlling variables for soil moisture dynamics in this mountain ecosystem. The freezing temperature in 0-100-cm soil depth was in the range of −1.66 to 1.73 °C, and the thawing temperature was in the range of −0.54 to 0.84 °C; soil aspect and water content were the main controlling factors in the freezing and thawing points in this mountain region. The results of this study contributed to identifying the major controls on soil moisture content in mountain ecosystems and will provide basis for ecological restoration in arid regions. [ABSTRACT FROM AUTHOR]

During the Early and Middle Holocene, large areas of today's arid regions in North and East Africa were populated by fisherhunter- gatherer communities who heavily relied on aquatic resources. In North Africa, Wavy Line pottery and harpoons are their most salient diagnostic features. Similar finds have also been made at sites in Kenya's Lake Turkana region in East Africa but a clear classification of the pottery was previously not available. In order to elucidate the cultural connections between Lake Turkana's first potters and North African groups, the pottery of the Koobi Fora region that was excavated by John Barthelme in the 1970/80s was re-assessed in detail. It was compared and contrasted - on a regional scale - with pottery from Lowasera and sites near Lothagam (Zu4, Zu6) and - on a supra-regional scale - with the pottery of the Central Nile Valley and eastern Sahara. The analyses reveal some significant points: Firstly, the early fisher pottery of Lake Turkana is clearly typologically affiliated with the Early Khartoum pottery and was thus part of the Wavy Line complex. Secondly, certain typological features of the Turkana assemblages, which include only a few Dotted Wavy Line patterns, tentatively hint to a date at least in the 7th millennium bp or earlier. Thirdly, the pottery features suggest that the East African fisher-hunter-gatherers adopted pottery from Northeast Africa. [ABSTRACT FROM AUTHOR]

[Display omitted] • Rainfall and flood frequency projections are developed for Australia. • Projections of rainfall and flood frequency are regionally consistent. • Frequent rainfalls are projected to increase across Australia. • Frequent floods are projected to decrease, particularly in the extra-tropics. • Rare floods are projected to increase in line with extreme rainfall projections. Flood damages are projected to increase with climate change due to intensification of extreme rainfalls, with water scarcity also projected to increase due to longer periods of drought leading to less runoff from flood events. In order to adapt to climate change, precise and robust projections of flood events are required of a magnitude (or rarity) relevant to engineering design and water resources planning. However, due to the complexity of catchment-specific processes which influence flood response, many studies disagree on the direction and magnitude of the projected change: some studies project increases in flood magnitude, even above projected increases in rainfall maxima, while other studies project decreases. Using a combination of continentally downscaled rainfall projections for Australia and rainfall-runoff models locally calibrated to rare floods using a novel objective function, we show that projected changes in flooding do not follow projected changes in extreme rainfall, with changes in flooding depending on region, runoff mechanism, and event severity. Decreases in frequent flooding up to the 1 in 5 annual exceedance probability are projected across the continent, with increases only projected for frequent flooding in some tropical regions, diverging from the projected increases in rainfall maxima across a majority of the continent. For rare events of annual exceedance probability 1 in 50, the flood magnitude is projected to increase across the northern and eastern coasts by the end of the century – commensurate with the median projected increase of 20% in rainfall maxima. However, decreases in both rainfall maxima and flooding are still projected for south-western Australia, even for the rarest events. The regional coherence of our results suggests the patterns in the projected changes may be applicable to other tropical, temperate, and arid regions around the world. [ABSTRACT FROM AUTHOR]

Hydrodynamic forces produced by breaking waves make the rocky intertidal zone one of the most physically stressful environments on the planet, and for many ecological studies, it is important to quantify intertidal flows. However, hydrodynamic measurements with a response time rapid enough to reliably identify 'impingement events' - large, transient increases in force occurring at wave arrival - have not been made, although impingement events are hypothesized to be the largest hydrodynamic forces in the intertidal zone. We built a custom force transducer to measure short-duration flows in the intertidal zone, and took measurements of force acting on both a drag sphere and a rigid limpet model. Based on our results, we estimate impingement events occur in 7-14% of waves, and when present, they are the dominant force in the wave. The mean ratio of maximum force to the second largest force within a wave was approximately 1.5 for impingement waves, in contrast to 1.2 for non-impingement waves. However, contrary to previous hypotheses, impingement events are not necessarily the largest forces imposed on intertidal organisms. At our site, non-impingement waves recorded on the drag sphere had a mean maximum force 61% greater than the mean maximum force of waves with impingement events. Our results thus suggest that impingement is not necessarily the greatest hydrodynamic danger to organisms. Future studies should use high temporal resolution measurements to identify the largest transient forces regardless of when they occur in a wave, and to assess how such brief forces might affect intertidal organisms. [ABSTRACT FROM AUTHOR]

Urbanization has brought about dramatic changes in the urban environment in China and its associated human population and transportation systems in recent years. However, urbanization in the oases of arid regions of China has been little studied and remains poorly understood. This paper aims to analyze spatiotemporal changes in an urban landscape along major vehicular road transects and compare the relationship between urban growth and transportation in Jiuquan, an oasis city in an arid region of China. We integrated remote sensing images, landscape metrics, and urban-rural gradient analysis to address these questions. The results showed that major vehicular roads stimulated Jiuquan's urban expansion, especially with regard to built-up land containing urban green land areas. Oasis urbanization not only increased landscape fragmentation and structural complexity, but also followed a linear branching, leapfrogging growth pattern characterized by “axial clumps” extending from downtown into rural areas along the road network. The primary source of urban land was not agricultural land, but unused land. These results also indicated that the transect approach implemented along representative roads was effective for studying the urbanization of oasis cities. Such an approach could be applied to master planning in similar oasis cities throughout arid China. [ABSTRACT FROM AUTHOR]

The present study focuses on drought analysis with an aim to understand the drought vulnerability, estimate and map the drought duration and severity in drought prone North Interior Karnataka region, India. A detailed analysis were carried out using rainfall data of more than 178 (with greater than 30 years data) stations to understand the drought characteristics. Rainfall descriptive variability, percentage occurrence of drought incidences and spatial distribution of rainfall were derived. In order to evaluate the drought severity and its extent and to map, method proposed by Ponce et al. () and the Geographic Information System has been used. The method by Ponce et al. () characterize drought based on intensity, duration and recurrence interval using mean annual precipitation of a location. The results obtained for the study area indicate that, the region is mostly semi-arid with drought occur for more than 50 % of the time. The majority of the drought events are of moderate intensity with few extreme intensity events. Further, it is noticed that, in many station, the rainfall show a decreasing trend. Since, rainfall in this region are mostly declining due to climatic change, the area would experience increasing drought severity in the forthcoming years. The outcome of the study would be useful in understanding the drought pattern, severity and extent in the study area which can be used by scientists and water management professionals to plan drought mitigation measures. [ABSTRACT FROM AUTHOR]

Surface hydrological behaviour is important in drylands because it affects the distribution of soil moisture and vegetation and the hydrological functioning of slopes and catchments. Microplot scale run-off can be relatively easily measured, i.e. by rainfall simulations. However, slope or catchment run-off cannot be deduced from microplots, requiring long-time monitoring, because run-off coefficients decrease with increasing drainage area. Therefore, to determine the slope length covered by run-off ( run-off length) is crucial to connect scales. Biological soil crusts (BSCs) are good model systems, and their hydrology at slope scale is insufficiently known. This study provides run-off lengths from BSCs, by field factorial experiments using rainfall simulation, including two BSC types, three rain types, three antecedent soil moistures and four plot lengths. Data were analysed by generalized linear modelling, including vascular plant cover as covariates. Results were the following: (i) the real contributing area is almost always much smaller than the topographical contributing area; (ii) the BSC type is key to controlling run-off; run-off length reached 3 m on cyanobacterial crust, but hardly over 1 m on lichen crust; this pattern remained through rain type or soil moisture; (iii) run-off decreased with BSC development because soil sealing disappears; porosity, biomass and roughness increase and some changes occur in the uppermost soil layer; and (iv) run-off flow increased with both rain type and soil moisture but run-off coefficient only with soil moisture (as larger rains increased both run-off and infiltration); vascular plant cover had a slight effect on run-off because it was low and random. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Researchers and practitioners of ecological restoration from South Africa and Western Australia recently undertook a travelling workshop across several South African biomes to discuss and evaluate the various approaches currently being utilised in the field. Key findings from the workshop highlighted the contrasting nature of ecological restoration undertaken in these two ecologically similar, but socially and politically different regions. [ABSTRACT FROM AUTHOR]

A provenance test was initiated in spring 2002 at the New Mexico State University Agricultural Science Center at Farmington to examine the adaptability of various hybrid poplar ( Populus spp.) crosses to the high elevation, semi-arid conditions of this region of the Southwestern United States. Ten crosses of P. deltoides, P. maximowiczii, P. nigra and P. trichocarpa obtained from nurseries in the Pacific Northwest were grown in replicates (3 plots × 16 trees) under drip irrigation programmed to match tree evapotranspiration (ET) rates. By the end of year 10, six crosses had maintained a 90 % or higher survival rate and had an average wood volume of 246 m ha. The P. deltoides × P. nigra ( P. × canadensis) clone OP-367 surpassed a ten-year commercial target of 25-cm diameter at breast height (DBH) after eight seasons, and by the end of 2011 attained a DBH of 28.0 cm, height of 19.9 m and wood volume of 473 m ha. Results suggest that hybrid poplar production is possible in this type of semi-arid environment using appropriate germplasm and drip irrigation regimes scheduled according to tree ET demand. [ABSTRACT FROM AUTHOR]

Multipurpose small reservoirs are important for livelihoods in rural semi-arid regions. To manage and plan these reservoirs and to assess their hydrological impact at a river basin scale, it is important to monitor their water storage dynamics. This paper introduces a Bayesian approach for monitoring small reservoirs with radar satellite images. The newly developed growing Bayesian classifier has a high degree of automation, can readily be extended with auxiliary information and reduces the confusion error to the land-water boundary pixels. A case study has been performed in the Upper East Region of Ghana, based on Radarsat-2 data from November 2012 until April 2013. Results show that the growing Bayesian classifier can deal with the spatial and temporal variability in synthetic aperture radar (SAR) backscatter intensities from small reservoirs. Due to its ability to incorporate auxiliary information, the algorithm is able to delineate open water from SAR imagery with a low land-water contrast in the case of wind-induced Bragg scattering or limited vegetation on the land surrounding a small reservoir. [ABSTRACT FROM AUTHOR]

Extreme environments, such as deserts and high-elevation ecosystems, are very important from biodiversity and ecological perspectives. However, plant physiology at those sites has been scarcely studied, likely due to logistic difficulties. In the present study, leaf physiological traits in native plants were analyzed from arid zones across an elevational transect in Western China, from Turpan Basin to the Qinghai-Tibet Plateau (QTP) at Delingha. The aim of this study was to use leaf physiological traits to help identifying potentially threatened species and true extremophiles. Physiological measurements in the field, and particularly in situ measurements of gas exchange and chlorophyll fluorescence, have been determined to be useful to determine the current state of plants at a given environment. Using this approach plus a combination of leaf traits, several species performing particularly well at the QTP were identified, e.g. Hedysarum multijugum , as well as at Manas drylands, e.g. Peganum harmala and Setaria viridis. On the other hand, several species showed marked signs of severe stress, in particular a very low photosynthetic rate over its potential maximum, as well as other negative traits, like low water and/or nitrogen-use-efficiency, which should be considered in conservation plans. Interestingly, all C 4 species studied except Setaria viridis were among the most stressed species. Despite their higher water use efficiency and drought-tolerance reputation, they presented a much larger photosynthesis depression than most C 3 species. This is an intriguing and interesting observation that deserves further studies. • Physiological traits were measured in the field from the Turpan Basin to the QTP. • Potential extremophile species were identified, as well as severely stressed species performing. • C 4 species were more affected by the prevalent stress conditions than most C 3 species. [ABSTRACT FROM AUTHOR]

Highlights: [•] The first tree-ring reconstructions of the Klamath River basin hydroclimate. [•] Longest reconstruction reaches 1000 CE. [•] Short and long dry periods were likely more severe from the 11th-to-13th century. [•] The early 20th century likely contains the most severe mid-length dry periods. [ABSTRACT FROM AUTHOR]

We evaluate the modelling of carbon fluxes from eddy covariance (EC) tower observations in different water-limited land-cover/land-use (LCLU) and biome types in semi-arid Inner Mongolia, China. The vegetation photosynthesis model (VPM) and modified VPM (MVPM), driven by the enhanced vegetation index (EVI) and land-surface water index (LSWI), which were derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) surface-reflectance product (MOD09A1), were used to model and validate the temporal changes in gross primary production (GPP) from the EC towers during the 2006 and 2007 growing seasons. The annual GPP predicted by the VPM model (GPPVPM) was predicted reasonably well in 2006 and 2007 at the cropland (coefficient of determination,R2 = 0.67 and 0.71, for 2006 and 2007, respectively) and typical steppe (R2 = 0.80 and 0.73) sites. The predictive power of the VPM model varied in the desert steppe, which includes an irrigated poplar stand (R2 = 0.74 and 0.68) and shrubland (R2 = 0.31 and 0.49) sites. The comparison between GPP obtained from the eddy covariance tower (GPPtower) and GPP obtained from MVPM (GPPMVPM) (predicted GPP) showed good agreement for the typical steppe site of Xilinhaote (R2 = 0.84 and 0.70 in 2006 and 2007, respectively) and for the Duolun steppe site (R2 = 0.63) and cropland site (R2 = 0.63) in 2007. The predictive power of the MVPM model decreased slightly in the desert steppe at the irrigated poplar stand (R2 = 0.56 and 0.47 in 2006 and 2007 respectively) and the shrubland (R2 = 0.20 and 0.41). The results of this study demonstrate the feasibility of modelling GPP from EC towers in semi-arid regions. [ABSTRACT FROM PUBLISHER]

Vertical electrical sounding technique (VES) is used as an alternative approach to pumping test for computing the Quaternary aquifer transmissivity in the Khanasser Valley, Northern Syria. The method is inexpensive, easy and gives faster results with higher special resolution than the traditional pumping technique. The hydraulic conductivity values obtained using VES agree with the pumping test results, which in the Khanasser Valley vary between the order of 0.864 and 8.64 m/day (10 and 10 m/s). The probable location of the Quaternary aquifer in the Khanasser Valley is obtained through the transmissivity map derived from VES. The knowledge of transmissivity is fundamental for modeling and management processes in the Khanasser Valley. Other similar semiarid regions can benefit from the approach successfully applied in the study area. [ABSTRACT FROM AUTHOR]

Abstract: Climate models often predict that more extreme precipitation events will occur in arid and semiarid regions, where C cycling is particularly sensitive to the amount and seasonal distribution of precipitation. Although the effects of precipitation change on soil carbon processes in desert have been studied intensively, how vegetation cover and rain timing co-regulate the responses of soil CO2 efflux to precipitation change is still not well understood. In this study, a field manipulative experiment was conducted with five simulated rain addition treatments (natural rains plus 0%, 25%, 50%, 75%, 100% of local annual mean precipitation) in a desert ecosystem in Northwest China. The rain addition treatments were applied with 16 field rain enrichment systems on the 10th day of each month from May to September, 2009. Soil water content, soil temperature and soil CO2 efflux rates were measured in both bare and vegetated soils before and after the rain addition during a 3-week period for each rain treatment. The response magnitude and duration of soil CO2 efflux to rain addition depended not only on the rain amount but also on the type of vegetation covers and the timing of rain addition treatments. Soil water content responded quickly to the rain addition regardless of rain amount and timing, but soil CO2 efflux increased to rain addition only in May–July but not in late growing season (September). In addition, soil CO2 efflux from the bare and vegetated soils showed similar increase to rain additions in May–July, but they demonstrated distinct responses to rain addition in September. The differences in the responses of soil CO2 efflux to rain addition between the bare and vegetated soils could be explained by the root activities stimulated by added rain water, while the difference in soil CO2 efflux response to rain addition among treatment times could be attributed to soil water condition prior to rain addition and/or soil temperature drop following rain addition. Thus, both vegetation cover and rain timing can co-regulate responses of soil CO2 efflux to future precipitation change in arid desert ecosystems, which should be considered when predicting future carbon balance of desert ecosystems in arid and semiarid regions. [Copyright &y& Elsevier]