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Mountains play a crucial role in shaping the climate of an area and subsequently, the environments and species that are suited to those particular conditions. Understanding the relationships between environmental conditions and their influence on the occurrence of a species is necessary to make informed decisions when conserving relevant habitats. This study evaluated and compared the potential for different interactions between climatic variables to describe the environmental preferences and the range of the Ladakh urial, a narrowly distributed sub‐species of Ovis vignei, in the arid Himalayas. Species distribution models were created from spatially thinned presence‐only occurrence data of 50 locations using a Maximum Entropy (Maxent) model. For this, we subdivided the modeled distribution into environmental categories with varying degrees of suitability. We identified a high cold precipitation to annual precipitation ratio typical of cold desert climates well suited to describe the highest quality environments for urial. The inverse, low warm precipitation to annual precipitation ratio was found to better describe the urial's range at the lower end of potential habitat. In this comparison, we observed that with the exclusion of unsuitable cold steppe habitat with a higher warm precipitation to annual precipitation ratio, we were able to refine the extent of this species range but at a trade‐off to the accurate description of high‐quality environments. This study demonstrated the strong potential of cold arid climatic conditions to describe the distribution of urial in India, which have implications for identifying important areas for the conservation and management of the species in the high altitude rangelands of Ladakh. [ABSTRACT FROM AUTHOR]

In nature, microbes do not thrive in seclusion but are involved in complex interactions within- and between-microbial kingdoms. Among these, symbiotic associations with mycorrhizal fungi and nitrogen-fixing bacteria are namely known to improve plant health, while providing resources to benefit other microbial members. Yet, it is not clear how these microbial symbionts interact with each other or how they impact the microbiota network architecture. We used an extensive co-occurrence network analysis, including rhizosphere and roots samples from six plant species in a natural desert in AlUla region (Kingdom of Saudi Arabia) and described how these symbionts were structured within the plant microbiota network. We found that the plant species was a significant driver of its microbiota composition and also of the specificity of its interactions in networks at the microbial taxa level. Despite this specificity, a motif was conserved across all networks, i.e., mycorrhizal fungi highly covaried with other mycorrhizal fungi, especially in plant roots—this pattern is known as assortativity. This structural property might reflect their ecological niche preference or their ability to opportunistically colonize roots of plant species considered non symbiotic e.g., H. salicornicum, an Amaranthaceae. Furthermore, these results are consistent with previous findings regarding the architecture of the gut microbiome network, where a high level of assortativity at the level of bacterial and fungal orders was also identified, suggesting the existence of general rules of microbiome assembly. Otherwise, the bacterial symbionts Rhizobiales and Frankiales covaried with other bacterial and fungal members, and were highly structural to the intra- and inter-kingdom networks. Our extensive co-occurrence network analysis of plant microbiota and study of symbiont assortativity, provided further evidence on the importance of bacterial and fungal symbionts in structuring the global plant microbiota network. [ABSTRACT FROM AUTHOR]

In this study, prominent dust source areas are identified along with their plume extent using high temporal frequency satellite observations. Hourly dust plume observations of the Dust Belt from geostationary‐orbit satellites are analyzed for the 2017‐12–2022‐11 period. To identify dust source areas and their extents, we back‐track plumes to their source, assessing source areas in terms of emission frequency, contribution, and plume extent patterns. This method advances over traditional source allocation techniques that rely on polar‐orbiting satellites based on a few daily passes and meteorological wind fields for backtracking. Our findings indicate that Boreal summer is the most intense season for most sources, except in the Southern Sahara, which experiences winterly winds. Our analysis also reveals significant contributions from regions within the Sahara that experience expansive but infrequent dust storms, highlighting the importance of considering both frequency and magnitude in understanding dust emissions. Plain Language Summary: This study focuses on the role of mineral dust, a significant climate constituent originating mainly from arid regions. Identifying where dust comes from and where it goes is essential for understanding how it affects the climate. To do so, we employ high temporal frequency satellite data to backtrack dust plumes to their sources, revealing key dust‐emitting regions and their seasonal variations. We also quantify each source area's frequency and magnitude of emissions and the spatial distribution of emanating dust plumes. Our findings show that summer is the peak season for most areas, except for the strongest dust sources, located in Southern Sahara, which peak in winter driven by seasonal winds. Additionally, some Saharan source areas exhibit severe storms but have been under‐emphasized because they were measured by the frequency of their storms. Key Points: High‐temporal‐resolution images from geostationary‐orbit satellites enable precise back‐tracking of dust source areasDust source areas are analyzed in terms of their emission frequency, contribution to the regional atmosphere, and corresponding plume extentSummer is the peak dust emission season for most sources in West Asia and Sahara and ephemeral lake beds are active during the dry season [ABSTRACT FROM AUTHOR]

A distinct coal break occurs widely in the late Early Jurassic in Central Asia, the cause of which, however, is still debated largely due to the uncertainty of its age constraint. In the Junggar Basin of northwestern China, this coal break coincides with the Sangonghe Formation, which is well exposed along the basin margins, and is mainly composed of lacustrine deposits rich in a variety of fossils, including plants, pollens and spores, bivalves, clam shrimps, insects and some vertebrates. Here we name them as the Sangonghe biota and review their biostratigraphic framework. The Sangonghe biota constrains the Sangonghe Formation to the late Pliensbachian to the early Aalenian. Abundant thermophilous plants and Classopollis, together with frequent occurrences of red beds and carbonate nodules in the middle part of the Sangonghe Formation, are indicative of an arid climate in Central Asia at that time. This arid interlude should be responsible for the coal break, which may be related to the global warming in the early Toarcian. However, more precise dating evidence is needed to substantiate this. [ABSTRACT FROM AUTHOR]

In the context of climate change, studying changes in rainfall patterns is a crucial area of research, remarkably so in arid and semi-arid regions due to the susceptibility of human activities to extreme events such as droughts. Employing predictive models to calculate drought indices can be a useful method for the effective characterization of drought conditions. This study applies two type of machine learning methods—long short-term memory (LSTM) and Neural Hierarchical Interpolation for Time Series Forecasting (N-HiTS)—to develop and deploy artificial neural network models with the aim of predicting the regional standardized precipitation index (SPI) in four regions of Zacatecas, Mexico. The predictor variables were a set of climatological time series data spanning from 1964 to 2020. The results suggest that the N-HiTS model outperforms the LSTM model in the prediction and forecasting of SPI time series for all regions in terms of performance metrics: the Mean Squared Error, Mean Absolute Error, Coefficient of Determination and ξ correlation coefficient range from 0.0455 to 0.5472, from 0.1696 to 0.6661, from 0.9162 to 0.9684 and from 0.9222 to 0.9368, respectively, for the regions under study. Consequently, the outcomes revealed the successful performance of the N-HiTS models in accurately predicting the SPI across the four examined regions. [ABSTRACT FROM AUTHOR]

This study proposes an innovative and sustainable solution for road repair using a variant of cold asphalt concrete obtained by combining petroleum sludges, serpentinites, and vitrified clay shales from the Moa region. This proposal aims to manage industrial waste more efficiently and reduce dependence on conventional construction material resources, thereby promoting sustainability in road repair. [ABSTRACT FROM AUTHOR]

Landscape productivity and resource dispersion are key drivers of the movement patterns of many species. In less productive environments, home ranges are generally larger as individuals travel further to access resources. The greater bilby (Macrotis lagotis) has been reintroduced to several feral predator exclosures to reduce their extinction risk. Understanding how landscape productivity and resource dispersion influence bilby space use is critical to enable effective management of populations in exclosures. At two exclosures, we tested three hypotheses: 1. Bilbies would preferentially utilize habitats with sandy substrates (<20% clay content), as they are suitable for digging burrows and foraging pits; 2. Home ranges would be larger at the arid site compared to the semi‐arid site due to lower productivity and patchier distribution of preferred habitats; and 3. Bilbies would travel further each night at the arid site to access preferred habitats. Rainfall was used as an indicator of productivity, and dispersion of preferred habitats as an indicator of resource dispersion. The study was undertaken during average rainfall conditions and under similar bilby population densities at both sites. GPS loggers recorded home ranges and movements of 10 bilbies at the arid site, and 11 bilbies at the semi‐arid site. Seventeen of the 21 bilbies preferentially utilized habitats with sandy substrates, which were less abundant at the arid site. There were no significant differences in home range size or nightly movements between the sites for either sex. We suggest the average rainfall conditions at both sites, and the dietary flexibility of bilbies, supported the maintenance of relatively small and stable home ranges (particularly for females). The effects of landscape productivity and resource dispersion on bilby space use are more likely to be evident during extended periods of below average rainfall. Bilby home range studies during low rainfall conditions (e.g. drought) are required for the effective, long‐term management of exclosure populations. [ABSTRACT FROM AUTHOR]

Drylands are characterized by high spatial variability in resource availability due to sporadic rainfall, topography of the landscape and important effects of animals. Resource availability gradients may trigger patterns in decomposer population abundances and activity, which could affect ecosystem functions such as decomposition. Here, we examined the influence of resource availability gradients on the importance of termites in the decomposition of wood and grass litter. We placed wood blocks and grass litter baits in bags accessible and inaccessible to termites across wood and grass resource gradients as determined by the presence or absence of a top mammalian predator and across topographic gradients during a 9‐month period in arid Australia. We hypothesized that grass‐eating termite activity would track grass abundance and wood‐eating termite activity would track wood abundance. Termites were the predominant decomposition agent at these sites. Termites contributed to 99.5% of wood decomposition and 83.9% of grass decomposition during our study period. For wood, the termite effect was spatially variable and increased with habitat wood availability, which was greatest on dunes and where top predators were absent. However, the contribution of termites to grass litter decomposition did not track grass availability or termite abundance. The highest effects of termites on grass decomposition rates were found in habitats where the absence of top predators led to low grass availability. Our findings highlight how spatial variability in resources in addition to other factors that we do not document but are known to be influenced by the presence of top predators, such as insectivore predation rates, across the landscape could affect ecosystem functions such as decomposition. [ABSTRACT FROM AUTHOR]

A near-global framework for automated training data generation and land cover classification using shallow machine learning with low-density time series imagery does not exist. This study presents a methodology to map nine-class, six-class, and five-class land cover using two dates (winter and non-winter) of a Sentinel-2 granule across seven international sites. The approach uses a series of spectral, textural, and distance decision functions combined with modified ancillary layers (such as global impervious surface and global tree cover) to create binary masks from which to generate a balanced set of training data applied to a random forest classifier. For the land cover masks, stepwise threshold adjustments were applied to reflectance, spectral index values, and Euclidean distance layers, with 62 combinations evaluated. Global (all seven scenes) and regional (arid, tropics, and temperate) adaptive thresholds were computed. An annual 95th and 5th percentile NDVI composite was used to provide temporal corrections to the decision functions, and these corrections were compared against the original model. The accuracy assessment found that the regional adaptive thresholds for both the two-date land cover and the temporally corrected land cover could accurately map land cover type within nine-class (68.4% vs. 73.1%), six-class (79.8% vs. 82.8%), and five-class (80.1% vs. 85.1%) schemes. Lastly, the five-class and six-class models were compared with a manually labeled deep learning model (Esri), where they performed with similar accuracies (five classes: Esri 80.0 ± 3.4%, region corrected 85.1 ± 2.9%). The results highlight not only performance in line with an intensive deep learning approach, but also that reasonably accurate models can be created without a full annual time series of imagery. [ABSTRACT FROM AUTHOR]

Considering several logistical limitations associated with live trapping in arid environments, owl pellet analysis provides a potentially useful alternative to estimate small mammal diversity. Owl pellet analysis has been used to estimate local small mammal diversity under the assumption that the method can reliably reflect the composition of local small mammal assemblages. However, the validity of owl pellet contents for use in ecological assessments has not been established. Thus, the present study aimed to determine the potential for eastern barn owl (Tyto delicatula) pellet analysis to improve the monitoring of small mammals in arid Australia. We analysed two ecological datasets from Pilungah Reserve on the northern boundary of the Simpson Desert in central Australia to assess their effectiveness for detecting expected small mammal species: 250 owl pellets collected from a known roosting site and 5 years of small mammal records from historical, long‐term trapping surveys. Species composition and detection probability of mammals varied depending on the method used. Owl pellet analysis returned higher species richness overall, while traditional trapping methods indicated a higher probability of detecting certain mammal species (e.g., the wongai ningaui Ningaui ridei, brush‐tailed mulgara Dasycercus blythi and the hairy‐footed dunnart Sminthopsis hirtipes). Importantly, analysis of owl pellets revealed two mammal species that had never been detected at the study site (dusky hopping mouse Notomys fuscus and Carpentarian false antechinus Pseudantechinus cf. mimulus). We suggest that owl pellet analysis could be particularly valuable when used as a precursor or in concert with traditional trapping to monitor and assist in the conservation of small mammal species in arid environments. [ABSTRACT FROM AUTHOR]

The objective was to determine a mathematical model to calculate the deposition velocity of the mud resulting from the washing of aggregates from the Jobo Base Business Unit of Sagua de Tánamo, which is transported by pipelines. Sampling, granulometric and densimetric analyzes were carried out and a complete factorial experiment design with four tests and two replications each was used. The input variable, percentage of solids, was studied at four levels (4%, 12%, 20% and 28%). It was determined that the clay contained in the mud, due to its predominant granulometry of less than 40 µm, classifies as silt. It was also revealed that the density of the solid is 1,901 kg/m3. The results of the deposition velocity determined by indirect measurement and those predicted by calculations using the Durand model were compared, with the aim of improving its precision and reliability, obtaining a relative coincidence error of less than 5%. A correction function is determined that quantifies the relationship between gravitational sedimentation velocity and deposition velocity. [ABSTRACT FROM AUTHOR]

Populations inhabiting several biomes may experience different abiotic and biotic conditions, exerting local selection pressures. Temperature and water regimes are interconnected variables, that may differ between biomes, and greatly influence ecophysiological traits, such as metabolic and evaporative water loss rates. We hypothesized that Ptyodactylus guttatus (Sinai Fan‐fingered Gecko) individuals, which occupy the Mediterranean and desert biomes across Israel, would follow the "metabolic cold adaptation" hypothesis and be adapted to the microclimate in the biome they inhabit. We thus predicted that desert individuals would prefer lower temperatures, and have lower resting metabolic rates and evaporative water loss rates at higher ambient temperatures than Mediterranean individuals. We also predicted that Mediterranean individuals would have a better body condition than individuals from the desert, because of higher primary productivity in the Mediterranean biome, and would therefore have higher mite loads. We further predicted that geckos from the desert would have longer limbs, enabling them to lose more heat to the environment, according to Allen's rule. To test these hypotheses, we measured the temperature preferences, field body temperatures, resting metabolic rates, evaporative water loss rates, body conditions, mite loads, and limb lengths of 82 P. guttatus individuals collected from four localities two from the desert biome and two from the Mediterranean biome. There were no significant differences in any of the tested traits when comparing between biomes. However, we found some differences in the evaporative water loss rates, body temperatures, body condition, and forelimb lengths between the northernmost and southernmost, and driest and wettest localities, supporting some of our predictions. Our results highlight the importance of the resolution of the analysis. Although some ecophysiological traits of P. guttatus seem to be conserved across localities and biomes, thermal plasticity in these traits may have helped this species reach its current distribution and occupy two biomes. [ABSTRACT FROM AUTHOR]

Litter decomposition is a key ecosystem process that determines rates of carbon and nutrient cycling. Photodegradation and soil-litter mixing have emerged as important drivers of dryland litter decomposition, but how these processes interact with decomposing microorganisms has received less attention. In this study, we examined the effects of ultraviolet-B radiation (UV-B; 280–315 nm) and soil-litter mixing on the decomposition of litter and its associated microbial community in an arid shrubland. We performed a full factorial litter decomposition experiment using leaf litter from a dominant shrub (Prosopis velutina) and a dominant grass (Eragrostis lehmanniana) that were exposed to solar radiation with near-ambient or attenuated UV-B, and were either soil-free or soil-covered; we then quantified litter decomposition and microbial community composition over a 12 month period. In general, shrub litter decomposed more rapidly than grass litter regardless of soil coverage, likely due to its lower C:N. Attenuation of UV-B had modest effects on decomposition but UV-B exposure did increase fungal biomass, perhaps reflecting facilitative aspects of photodegradation. Both bacteria and fungi emerged as important regulators of decomposition, and microbial decomposition was indirectly mediated by litter C:N, soil coverage, and UV-B effects on the microbial community. Bacterial colonization was inhibited in soil-free treatments, but was facilitated when litter was soil-covered. These findings suggest that UV-B may play an important role in facilitating fungal decomposition of litter, while soil-litter mixing is fundamental for promoting bacterial decomposition of litter. Highlights: Soil-litter mixing enhanced bacterial colonization of litter. Fungi are present on dryland litter regardless of soil and UV-B conditions. Soil-litter mixing initially accelerated litter decomposition but subsequently reduced it. [ABSTRACT FROM AUTHOR]

Premise of research. Woody plant expansion is a global problem in which trees and/or shrubs replace herbaceous species. Often the woody plants are native species, and the expansion may be attributable either to natural stochasticity or to changes in management of grazing or fire. In other cases, woody plant species are expanding their historic range, and changes in management may be insufficient to explain observed changes in range. One possible mechanism is adaptation of populations at the range edge to the local environment. Methodology. We investigated drought responses of plants sourced from three populations of the widespread, grassland-encroaching Juniperus virginiana and one population of the more drought-resistant Juniperus scopulorum. Seedlings of the four different populations were grown in a common garden in northeast Ohio, part of the native range of J. virginiana. We exposed plants to either an acute or chronic drought and determined water potential at 50% loss of function (P 50) for shoots. Pivotal results. The most resistant shoot P 50 measured ranged from 2.7 to 4.7 MPa less negative than P 50 reported in the literature for woody tissues. Juniperus virginiana plants sourced from the most arid site maintained high stomatal conductance when water was available and retained hydraulic conductance at lower water potentials compared to J. virginiana from wetter locations. Juniperus virginiana from the most arid site exhibited the largest hydraulic safety margin, with shoot P 50 as much as 3.25 MPa less negative than minimum shoot water potentials measured. Conclusions. Our data show that estimates of Juniperus spp. drought tolerance based on woody tissues misrepresent actual plant drought response. Juniperus virginiana plants from more arid sites exhibit a more exploitative water use strategy, which could promote expansion by facilitating rapid water uptake in pulse-driven systems, while a decrease in hydraulic conductance in shoots could promote survival by preventing hydraulic failure of more costly woody tissue. [ABSTRACT FROM AUTHOR]

Sand dunes cover more than half a million hectares of Khuzestan Province in Iran. These areas are a serious threat to agricultural lands, buildings, and industrial facilities. Knowing the characteristics of these lands helps a lot to manage and control this threat. This research was done to determine the characteristics of sand dunes of Khuzestan Province and their management. The results showed that the dynamic characteristics of sand dunes, such as salinity, are different depending on the location and direction of the prevailing wind. However, the organic carbon, cation exchange capacity, and acidity (pH) were similar in all regions. Soluble K was inversely related to salinity. In the western regions, carbonates (lime and dolomite) along with quartz, kaolinite, chlorite, and illite were the dominant minerals, and smectite, palygorskite, and vermiculite were in the next order. The southeastern parts had a similar composition, but the proportion of minerals was different based on the location, especially for polygorskite. The proportion of smectite, polygorskite, and sepiolite minerals was high in the direction of prevailing winds, but their amount decreased in the inner parts. Sepiolite was observed only in the southeastern regions, which was related to the origin of gypsum soils in the neighborhood areas. A similar composition of these minerals and their proportion was also seen in the deeper parts. The similarity of the sand dunes minerals shows that they have the same origin and their similarity with the composition of soil minerals in the plains of Khuzestan indicating that these sands were formed from the wind erosion of the plain during different dry periods. [ABSTRACT FROM AUTHOR]

Precipitation variability and heatwaves are expected to intensify over much of inland Australia under most projected climate change scenarios. This will undoubtedly have impacts on the biota of Australian dryland systems. However, accurate modelling of these impacts is presently impeded by a lack of empirical research on drought/heatwave effects on native arid flora and fauna. During the 2018–2021 Australian drought, many parts of the continent's inland experienced their hottest, driest period on record. Here, we present the results of a field survey in 2021 involving indigenous rangers, scientists and national parks staff who assessed plant dieback during this drought at Uluru‐Kata Tjuta National Park (UKTNP), central Australia. Spatially randomized quadrat sampling of eight common and culturally important plants indicated the following plant death rates across UKTNP (in order of drought susceptibility): desert myrtle (Aluta maisonneuvei subsp. maisonneuvei) (91%), yellow flame grevillea (Grevillea eriostachya) (79%), Maitland's wattle (Acacia maitlandii) (67%), waxy wattle (A. melleodora) (65%), soft spinifex grass (Triodia pungens) (53%), mulga (A. aneura) (42%), desert oak (Allocasuarina decaisneana) (22%) and quandong (Santalum acuminatum) (0%). The sampling also detected that seedling recruitment was absent or minimal for all plants except soft spinifex, while a generalized linear mixed model (GLMM) indicated two‐way interactions among species, plant size and stand density as important predictors of drought survival of adult plants. A substantial loss of biodiversity has occurred at UKTNP during the recent drought, with likely drivers of widespread plant mortality being extreme multi‐year rainfall deficit (2019 recorded the lowest‐ever annual rainfall at UKTNP [27 mm]) and record high summer temperatures (December 2019 recorded the highest‐ever temperature [47.1°C]). Our findings indicate that widespread plant death and extensive vegetation restructuring will occur across arid Australia if the severity and frequency of droughts increase under climate change. [ABSTRACT FROM AUTHOR]

Many rail species' distribution and habitat requirements are poorly known. We conducted a survey of the distribution of the Water Rail Rallus aquaticus across Algeria and investigated its possible nesting in the Sahara. Between 2002 and 2008, water rails were recorded in nine sites across Algeria and were found to breed in Lake Fetzara. In 2022, the species was recorded at yet another site, El Ménia, where two nests were found to contain clutches of three and seven eggs, respectively. This is the first unequivocal record of the Water Rail breeding in the Sahara. [ABSTRACT FROM AUTHOR]

Irruption of herbivore populations due to the extirpation of predators has led to dramatic changes in ecosystem functioning worldwide. Herbivores compete with other species for their primary source of nutrition, plant biomass. Such competition is typically considered to occur between species in closely related clades and functional groups but could also occur with detritivores that consume senescent plant biomass. In this study, we tested predictions that in ecosystems where herbivores are not regulated by predators, their indirect impacts on dead vegetation increase with primary productivity and extend to termites that feed on senescent vegetation. We compared dead vegetation cover and termite activity in herbivore exclosures and associated grazed plots at three locations situated along a rainfall gradient in arid Australia where kangaroo populations have irrupted. Dead vegetation cover and termite activity increased with rainfall in ungrazed plots but showed a negligible response to rainfall in grazed plots. Our results suggest that grazing can disrupt the flow of energy to detritivores and decouple the relationship between termite activity and primary productivity. Such disruption could have far‐reaching impacts on arid ecosystems because many organisms sit within "brown food webs" that are sustained by energy derived from the decomposition of senescent plant tissues. [ABSTRACT FROM AUTHOR]

A previous study on the feeding habits of Moorish tortoises in west-central Morocco suggests that these animals are selective herbivores, but the nutritional consequences have not been examined. Because of the potassium excretion load, which requires water and/or nitrogen loss, we predicted that tortoises do not have salt glands. Moorish tortoises prefer plants rich in water and protein but low in potassium (PEP index). To this end, we studied the spring diet of adult tortoises in an arid steppe in west-central Morocco during two seasons of relatively dry years (2011-2012) using feces analyses. We also estimated the relative abundance of potential food plants by stratified sampling under the canopy of jujube bushes Ziziphus lotus. We statistically compared diet to plant abundance. Finally, we assessed plant species' nutritional composition (water, crude protein, and potassium) available to tortoises. Results showed that species assemblages differed significantly between the two plant communities in both years. Nevertheless, tortoises consumed only about 5-6 and nearly the same species at the study site in 2011 and 2012, respectively. The plants consumed by the tortoises had the highest positive PEP index values indicating that there was more water and nitrogen in the food than is needed to excrete potassium. [ABSTRACT FROM AUTHOR]

We used the mark-recapture method to gather fundamental information on the population dynamics of Ischnura elegans (Vander Linden, 1820) in an arid region of central Iran. Ischnura elegans expresses female-limited colour polymorphism. We investigated sex and female morphs differences in survival and capture probabilities, space use patterns and spatial density. We used Cormack–Jolly–Seber and spatial capture-recapture models. The estimated capture probability for males was lower than females. The survival probability was not different between either males and females or gynomorphs and andromorphs. We found support for sex differences in density and detection probability, and female morphs differences in density, space use and detection probability. Based on our results the extreme conditions of arid regions can lead to a male-biased dispersal. Our findings also confirm the existence of behavioural differences between andromorph and gynomorph females and suggest a within species spatial habitat partitioning. [ABSTRACT FROM AUTHOR]

Landscape‐scale conservation that considers metapopulation dynamics will be essential for preventing declines of species facing multiple threats to their survival. Toward this end, we developed a novel approach that combines occurrence records, spatial–environmental data, and genetic information to model habitat, connectivity, and patterns of genetic structure and link spatial attributes to underlying ecological mechanisms. Using the threatened northern quoll (Dasyurus hallucatus) as a case study, we applied this approach to address the need for conservation decision‐making tools that promote resilient metapopulations of this threatened species in the Pilbara, Western Australia, a multiuse landscape that is a hotspot for biodiversity and mining. Habitat and connectivity were predicted by different landscape characteristics. Whereas habitat suitability was overwhelmingly driven by terrain ruggedness, dispersal was facilitated by proximity to watercourses. Although there is limited evidence for major physical barriers in the Pilbara, areas with high silt and clay content (i.e., alluvial and hardpan plains) showed high resistance to dispersal. Climate subtlety shaped distributions and patterns of genetic turnover, suggesting the potential for local adaptation. By understanding these spatial–environmental associations and linking them to life‐history and metapopulation dynamics, we highlight opportunities to provide targeted species management. To support this, we have created habitat, connectivity, and genetic uniqueness maps for conservation decision‐making in the region. These tools have the potential to provide a more holistic approach to conservation in multiuse landscapes globally. [ABSTRACT FROM AUTHOR]

The influence of resource availability on ecosystem function varies spatially and temporally, among and within ecosystems. Dramatic shifts in moisture‐driven resources can drive bottom‐up effects on animal behaviours and distributions. Further, complexity arises when landscapes are influenced by large mammalian grazers and predator‐induced trophic cascades, such as those mediated by the dingo (Canis familiaris (Dingo)) in the eastern arid Strzelecki Desert in Australia. During the driest two‐year period on record for this region, we investigated the persistence of avian communities associated with structurally distinct dunes and swale habitats, and across two different land management regimes (pastoral land with livestock and dingoes, and Sturt National Park managed for conservation without these animals). We grouped all birds into dietary functional groups to infer patterns of habitat use associated with available resources. We also compared incidental observations of the 'winter' bird community in part of the study region between the extended dry period of 2018/2019 and wet period of 2020/2021. Despite habitat partitioning, the avian community did not differ between land management regimes except in species richness during the dry period, likely driven by the low numbers of birds present during the surveys. Incidental observations indicated that insectivorous and omnivorous species dominated the bird community in the dry period, with granivorous species forming a greater proportion of the bird community during wet times. Birds with completely or partially insectivorous diets dominated avian species composition on surveys in the dry period, but there were distinct structural vegetation associations among functional groups, indicating that heterogeneity in vegetation structure was likely important for the conservation of refuges, which enable the persistence of avifauna during extended dry periods. Distinct habitat type, structure and available resources shaped avian communities in this landscape, during the extremely resource‐limited extended dry period, with implications for conservation and management, particularly given the increasing drying effects of climate change. [ABSTRACT FROM AUTHOR]

Background and Aims Understanding how genetic diversity is distributed and maintained within species is a central tenet of evolutionary and conservation biology, yet is understudied in arid regions of the globe. In temperate, glaciated environments, high genetic diversity in plant species is frequently found in refugial areas, which are often associated with southern non-glaciated landscapes. In arid, unglaciated environments, landscape features providing mesic conditions are likely to be refugia, although our understanding needs more refinement in these biomes. We test whether refugia and nuclear diversity hotspots occur in high-elevation, topographically complex areas for co-distributed shrubs (Petalostylis labicheoides and Indigofera monophylla ; Fabaceae) in the ancient, arid Pilbara bioregion of north-western Australia. Methods We conducted extensive sampling of the Pilbara (>1400 individuals from 62 widespread populations) to detect patterns in nuclear diversity and structure based on 13–16 microsatellite loci. Evidence of historical refugia was investigated based on patterns of diversity in three non-coding chloroplast (cp) sequence regions for approx. 240 individuals per species. Haplotype relationships were defined with median-joining networks and maximum likelihood phylogenetic trees. Key Results We found cpDNA evidence for a high-elevation refugium in P. labicheoides but not for I. monophylla that instead exhibited extraordinary haplotype diversity and evidence for persistence across a widespread area. Nuclear diversity hotspots occurred in, but were not exclusive to, high-elevation locations and extended to adjacent, low-elevation riparian areas in both species. Conclusions Phylogeographic refugia in arid environments may occur in high-elevation areas for some species but not all, and may be influenced by species-specific traits: a mesic montane refugium in P. labicheoides could be related to its preference for growth in water-gaining areas, while a lack of such evidence in I. monophylla could be related to maintenance of cpDNA diversity in a large soil seed bank and dynamic evolutionary history. Mesic environments created by the intersection of topographically complex landscapes with riparian zones can be contemporary reservoirs of genetic diversity in arid landscapes. [ABSTRACT FROM AUTHOR]

Simple Summary: Aedes aegypti is a mosquito that is responsible for spreading viral diseases including dengue fever, Zika, and chikungunya. Disease spread can be reduced by releasing mosquitoes containing bacteria known as Wolbachia, which inhibit transmission. Before such releases, it is important to collect data about where Ae. aegypti occur in urban landscapes and how populations vary over space and time. In this study, we present a pre-release analysis of mosquito populations using ovitraps (traps that provide a substrate for female mosquitoes to lay eggs), in Jeddah, Saudi Arabia. Our study contains a number of important findings. Firstly, we showed that there was no difference in the numbers of eggs laid between basement and non-basement locations. Secondly, we showed that, for some study sites, there was significant spatial structure to populations, meaning that where numbers of eggs were high (or low) they tended to remain high (or low) on average for many hundreds of meters. We also found that when mosquitoes are present in an area during the dry season, they tend to remain into the wet season; however, regions of high egg production could change between seasons. This suggests that in Jeddah's arid environment, the quality of breeding environments is inconsistent over time. Releases of Aedes aegypti carrying Wolbachia bacteria are known to suppress arbovirus transmission and reduce the incidence of vector-borne diseases. In planning for Wolbachia releases in the arid environment of Jeddah, Saudi Arabia, we collected entomological data with ovitraps across a 7-month period in four locations. Herein, we show that mosquito presence in basements does not differ from that of non-basement areas of buildings. In modelling mosquito presence across the study sites, we found the spatial structure to be statistically significant in one of the four sites, while a significant spatial structure was found for egg production data across three of the four sites. The length scales of the spatial covariance functions fitted to the egg production data ranged from 143 m to 574 m, indicating that high productivity regions can be extensive in size. Rank-correlation analyses indicated that mosquito presence tended to persist from the dry to wet season, but that egg production ranks at locations could reverse. The data suggest that, in Jeddah, the quality of the local environment for breeding can vary over time. The data support the feasibility of dry season releases but with release numbers needing to be flexible depending on local rates of invasion. [ABSTRACT FROM AUTHOR]

Prickly pear is a species that shows great capability to grow in harsh environments with potential for being used as an energy resource. The aim of this paper was to characterize prickly-pear mature cladodes in terms of chemical, proximal, and fuel properties, as well as to study the drying kinetics of this biomass after pretreatments destined to expose the internal tissues of mature cladodes to different temperatures. The results show that prickly-pear biomass was a poor-quality solid biofuel due to a low calorific value (12.9 MJ/kg d.m.b.) and a high ash content (25.8 wt.%). When drying prickly-pear biomass, cutting the cladodes to expose the internal tissues significantly increased the drying rate, especially when temperatures of 60 °C and above were employed. Double exponential (three parameters) and Midilli were the models that best fitted the experimental curves of prickly-pear cladodes cut into straps and cubes when dried at 50–70 °C. Finally, the bulk density of the prickly-pear biomass was similar to the one obtained for herbaceous biomasses, thus suggesting that further densification will enhance the usability of this feedstock. [ABSTRACT FROM AUTHOR]

Lichens are significant components of the biological soil crust communities in gypsum ecosystems and are involved in several processes related to ecosystem functioning, such as water and nutrient cycles or protection against soil erosion. Although numerous studies centered on lichen taxonomy and ecology have been performed in these habitats, global information about lichen species from gypsum substrates or their distributional ranges at a global scale is lacking. Thus, we compiled a global data set of recorded lichen species growing on gypsum. This review is based on systematic searches in two bibliographic databases (Web of Science and the more specialized database Mattick's Literature Index) using various keywords related to the substrate or ecology (i.e., gypsum, gypsiferous, semiarid, saxicolous, terricolous). In addition, we revised lichen literature from countries with gypsum soils using Mattick's, Hamburg University's Worldwide checklist, and different national lichen checklists. Ultimately the review includes a total of 321 studies. This data set included 6114 specimen records belonging to 336 recorded lichen species from 26 countries throughout the world. The results showed large differences in the number of species recorded among countries, reflecting differences in the sampling effort. We provide a table with the number of studies and species in relation to gypsum surface in order to account for the bias produced by sampling effort. The number of studies carried out per country was not related to the gypsum surface but probably to other factors, such as accessibility to field sampling, economic or political factors, or the presence of a wider community of lichenologists. Thus, Spain and Germany hosted the highest number of recorded species (160 and 114 species, respectively). Outside the European continent, only a few countries had a large number of species: Morocco (46), United States (42), and Iran (37). Remarkably, countries from the southern hemisphere (i.e., Australia, Chile, Namibia, and South Africa) showed a low number of studies from gypsum lands, supporting the stated biases observed in sampling efforts among countries. Considering the most studied countries, the results show that Teloschistaceae was the most represented family in gypsum ecosystems followed by Verrucariaceae and Cladoniaceae. Regarding particular species, Psora decipiens and Squamarina lentigera were some of the most widespread and abundant species in these habitats. This data set constitutes a basic and first step toward a much more comprehensive database, to be periodically updated in future releases, which also serves to identify countries or territories where future studies should be accomplished. There are no copyright restrictions on the data; please cite this data paper if the data are used in publications and teaching events. [ABSTRACT FROM AUTHOR]

Species richness is a fundamental component of ecological research including restoration. Managing for enhanced native species richness in restoration is a powerful goal and outcome; nonetheless, local species richness can also be used as a proximate mechanism to decide on the lands to acquire, protect, and restore. Here, a meta‐analysis was used to test the hypothesis that local species richness is a viable consideration in predicting varied restoration outcomes as identified by the primary researchers for drylands. In all dryland contexts, the most effective restoration outcomes across varied restoration interventions were at mid‐to‐relatively lower species rich sites. Consequently, restoration of degraded or low diversity arid grasslands is an important strategic opportunity during the UN Decade on Ecosystem Restoration, and plant species richness is an excellent starting point to inform decisions. [ABSTRACT FROM AUTHOR]

Litter decomposition plays a central role in carbon cycling in terrestrial ecosystems worldwide. In drylands, which cover 40% of the Earth's land surface, photodegradation and biotic decomposition driven by non‐rainfall moisture are important mechanisms of litter decay, though studies have only recently begun examining interactions between these two processes. We describe a novel priming mechanism in which photodegradation and biotic decay of the cuticle of plant litter increase litter absorption of non‐rainfall moisture (fog, dew and water vapor), supporting greater microbial decomposition.We used several field experiments in a coastal fog desert and a series of in situ observations to demonstrate a relationship between solar radiation, cuticle integrity, water absorption rates and mass loss.Experimentally attenuating solar radiation for 36 months slowed mass loss, reduced cuticle degradation and decreased litter moisture uptake relative to litter under ambient sunlight controls. In a separate field experiment, removing the cuticle of recently senesced grass tillers increased mass loss fourfold over 6 months relative to controls. Tillers with degraded cuticles also absorbed 3.8 times more water following an overnight dew event than did those with intact cuticles. Finally, fungal growth was consistently greater on the sun‐facing side of in situ tillers than on the shaded side, coincident with greater cuticle degradation.We present a conceptual model where the cuticle of plant litter acts as a water‐resistant barrier that is first degraded by solar radiation and surficial microbes, increasing litter's ability to absorb enough water during non‐rainfall moisture events to support substantial biotic decomposition inside the tissue. Considering how photodegradation and non‐rainfall moisture are both substantial drivers of litter decomposition in drylands, understanding how they interact under realistic field conditions will help us better predict how these systems are responding to changing climate regimes. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Where they occur at high densities, herbivores are likely to impact ecosystems by functioning as nutrient vectors that shift nutrients from areas where they graze to other locations. Such lateral shifts in nutrients are important to understand as they can alter the balance of species interactions and composition of ecological communities. In arid Australia, kangaroo (Macropus spp.) populations have irrupted due to suppression of their chief predator and their presence can have marked impacts on vegetation and soils in areas where they graze. Kangaroos are hypothesised to facilitate the transport of nutrients by ingesting organic material and depositing it in the form of faecal matter and urine under the shade of trees where they rest during the day. Here, we investigate the role that kangaroos and shade play as nutrient vectors and nutrient sinks, respectively. We compared kangaroo visitation and soil nutrients under experimental shades with unshaded areas in an arid landscape with little natural shade. Kangaroo visitation was greatest at shaded plots. Dung accumulation was greater at shaded plots than unshaded plots. Total carbon (TC) was greater in soils within shaded plots than control plots; however, there was no difference in TC between shaded plots and procedural control plots. There was no difference in total nitrogen and plant available phosphorus between shaded, control and procedural control plots. Our findings demonstrate that the presence of shade in an arid landscape influences the microhabitat choice of kangaroos, but only partially supports the hypothesis that nutrients concentrate within the soil under shade. • Accumulation of kangaroo dung was greater in shaded plots than unshaded plots. • Kangaroos frequented shaded plots more than unshaded plots. • A significant difference in total carbon was found between shade and control plots. [ABSTRACT FROM AUTHOR]

Food resources in arid habitats are important for the survival of native fauna, especially where resources provide water or key nutrients during dry periods. However, food resource plants can be susceptible to grazing species or may not be suitable for revegetating arid areas. Pimelea microcephala subsp. microcephala (P.m.microcephala) is an Australian dioecious shrub bearing bright fruit that are likely to attract birds. The plant is also noted for its production of simplexin, a compound toxic to mammals. The aims of our study were 1) to assess the nutrient and simplexin content of P.m.microcephala fruits, and 2) to confirm the identity of native avian species that consume the fruits. With both pieces of information, we could then determine the conservation utility of P.m.microcephala. Combining chemical analysis of fruit nutrients with field observations, we found that ripe fruits contain 60.5% water, 2.8% sugar, and potent antioxidants, which would likely be of nutritional benefit to consuming frugivores. The fruits also contain high levels of the toxin simplexin, which comprised 3.6% of ripe fruits by weight. We identified eight bird species interacting with P.m.microcephala, with at least five of these consuming ripe fruits. Our study demonstrates the potential for P.m.microcephala to contribute to revegetation and provide a food resource for arid zone birds, whilst being protected from grazing by the presence of simplexin. Further studies are needed to establish the species' absolute significance in terms of fruits as a source of water and nutrients to arid zone bird diets. [ABSTRACT FROM AUTHOR]

The predator satiation (PS) hypothesis of masting holds that seeding periodicity among plant populations enhances seed survival by starving granivores during low‐output periods and satiating reduced consumer populations during mast (high‐output) years. Although well‐studied in the northern hemisphere and in New Zealand, the PS hypothesis has received scant research attention in Australia. This is despite vegetation communities across nearly half the continent being dominated by masting species subject to high levels of seed predation (e.g. mulga [Acacia aneura] shrublands and spinifex [Triodia spp.] grasslands). Here, phenological monitoring and experimental testing of the PS hypothesis in the desert masting grass Triodia pungens (soft spinifex) occurred over 10 years at Deep Well station, central Australia. Field evidence supported the hypothesis that masting enhances seed escape from predators, as mean proportion seed survival at experimental bait stations was significantly greater during mast years (0.38 in 2012 and 0.33 in 2017) than during inter‐mast years (0.01 in 2016 and 2018). The possibility that seed decay as opposed to consumption affected results was controlled for by a deterioration experiment that indicated no significant loss of seed viability after 6‐months burial. The results support the hypothesis that masting in T. pungens is an adaptive trait related to the satiation of seed predators. However, whether masting enhances seed escape because predators are satiated at higher seed densities (i.e. masting causes a predator functional response) and/or because frequent low‐output periods reduce predator populations and make satiation more likely (i.e. a numerical predator masting response), remains unresolved. Aside from T. pungens, there are numerous other plants of the Australian arid zone that experience high levels of granivory and display masting. Seed predation may be a more important selective force acting on arid Australian plant reproduction than previously thought. [ABSTRACT FROM AUTHOR]

The olive tree is well known for being adapted to the arid conditions of the Mediterranean basin. However, prolonged drought periods which are expected to become more frequent because of climate change could result in severe water stress. In order to map the spatial distribution of drought stress in the olive groves in the arid regions of southeastern Tunisia (governorate of Médenine), we made recourse to the HidroMORE model (based mainly on FAO56 ET, NDVI from Sentinel 2 images and other physical parameters) to compute the water balance in a GIS environment. The outputs were compared to in situ soil water content measurements in four selected sites representing the various agro-ecological zones (mountains, piedmont, inner plain and coast) of the study site during the observation period from January 2016 to December 2019. The model outputs performed relatively well (the overall correlation coefficient R2=0.72; index of agreement IA=0.76). The simulation results show that during normal years or average droughts, the water stress is least in the mountain and piedmont zones because of the additional runoff water supplied by the traditional water harvesting structures (Jessour and Tabias) and in the coastal zone, thanks to the higher air humidity and rainfall. In contrast, the olives in the inner plains are the most affected. Nevertheless, in case of severe droughts, the stress is generalised. Thus, the model could be used as a decision tool for prioritizing areas of intervention for drought control and mitigation (supplemental irrigation for trees safeguard, etc.) [ABSTRACT FROM AUTHOR]

It is critical to identify the assembly processes and determinants of soil microbial communities to better predict soil microbial responses to environmental change in arid and semiarid areas. Here, soils from 16 grassland-only, 9 paired grassland and farmland, and 16 farmland-only sites were collected across the central Inner Mongolia Plateau, covering a steep environmental gradient. Through analyzing the paired samples, we discovered that land uses had strong effects on soil microbial communities but weak effects on their assembly processes. For all samples, although no environmental variables were significantly correlated with the net relatedness index (NRI), both the nearest taxon index (NTI) and the β-nearest taxon index (bNTI) were most related to mean annual precipitation (MAP). With the increase of MAP, soil microbial taxa at the tips of the phylogenetic tree were more clustered, and the contribution of determinism increased. Determinism (48.6%), especially variable selection (46.3%), and stochasticity (51.4%) were almost equal in farmland, while stochasticity (75.0%) was dominant in grassland. Additionally, Mantel tests and redundancy analyses (RDA) revealed that the main determinants of soil microbial community structure were MAP in grassland but mean annual temperature (MAT) in farmland. MAP and MAT were also good predictors of the community composition (the top 200 dominant operational taxonomic units) in grassland and farmland, respectively. Collectively, in arid and semiarid areas, soil microbial communities were more sensitive to environmental change in farmland than in grassland, and unlike the major impact of MAP on grassland microbial communities, MAT was the primary driver of farmland microbial communities. [ABSTRACT FROM AUTHOR]

In arid environments, shade provided by vegetation forms the crux of many facilitation pathways by providing other organisms with relief from high levels of solar radiation and extreme temperatures. Shade is an important determinant that structures arid ecosystem processes and functioning. While shade is considered an essential refuge for many organisms in arid environments, few studies have assessed how parasitic plants such as aerial mistletoes can influence the quality of shade provided by its host, and how this can subsequently influence species interactions. Here, we investigate how mistletoe influences the microclimate and daytime use of sub-canopy habitat by a large herbivore that seeks out shady micro-habitats to avoid daytime heat in Australia's Strzelecki Desert. We experimentally removed the pale-leaved mistletoe (Amyema maidenii) from mulga trees (Acacia aneura) and monitored sub-canopy ambient temperatures and the daytime use of sub-canopy habitat by red kangaroos (Osphranter rufus). Results showed that average hourly temperature during the daytime and daily maximum temperature were cooler and that kangaroos were approximately three times more likely to shelter beneath trees where mistletoe was present (control) compared to where mistletoes had been removed (treatment). By showing that mistletoe can improve the quality of shade provided by their host trees, our study offers a novel insight into how mistletoes can facilitate the surrounding biota through modifying the abiotic environment beyond its physical structure. More broadly, the results of our study emphasise the prevalence of positive interactions within ecological communities and how they can occur in unexpected ways and indirectly between organisms that never come into direct contact. [ABSTRACT FROM AUTHOR]

Considering three sites under different climate conditions (arid, semi-arid, and subhumid), this study aims to use the vadose-zone water stable isotope profiles to estimate the groundwater recharge rate. High-resolution vertical subsurface soil sampling along the vadose zone of the investigated sites was conducted. The collected samples were analysed to determine their stable isotope ratios (δ2H and δ18O) that were used along with the piston displacement method to estimate recharge. Annual recharge rates of 0.2% (± 0.1%), 2.5%, and 18% of the total annual precipitation were obtained for the arid, semi-arid, and subhumid sites, respectively. Recharge rates at the semi-arid and subhumid sites are comparable to those previously estimated using water balance-based methods. The recharge rate at the arid site is lower than that previously estimated for that site using the water budget-based method, revealing difficulties in applying the piston displacement method under an arid regime. [ABSTRACT FROM AUTHOR]

Considering water scarcity in Saudi Arabia, flied experiment was performed to assess the growth, grain yield and grain elements content of locally cultivated barley (Hordeum vulgare L.). Ten landraces were irrigated with three irrigation water sources, tap water (TW), underground water (UW) and treated municipal wastewater (TMW). Significant increase of: growth such as height, tillers and spike length, and number and yield traits, 1000 grain weight and maximum yield per individual plant were recorded in plants treated with TMW compared to the other two irrigation treatments. Further, interaction of irrigation treatments and landraces significantly improved growth and plant yield of LR3 (Ad-Dilam local barley), LR5 (Buraidah local barley) and LR6 (Asir barley) treated with TMW (had the highest height, maximum tiller number, spikes length cm), and grain per spike and plant. Macro and microelement accumulation increased in the grain of barley landraces irrigated with TMW. However, trace elements levels did not exceed safe limits, with exception of Cd in all barley landraces grain was higher > 0.2 mg kg-1. Nevertheless, landraces LR6 (Asir barley) LR7 (Buraydah barley) and LR8 (Hail barley) accumulated Cd within safe limit. TMW is a viable choice for some barley cultivation sustainability to safe drinking and ground water. [ABSTRACT FROM AUTHOR]

Animals that live in hot environments must deal with extreme temperatures and overcome the constraints imposed by overheating. Some species exhibit remarkable adaptations to control body temperature, usually in the form of structures that act as thermal windows to cool down the body by dissipating heat. Here, we describe the case of the dragonfly Zenithoptera lanei , which inhabits open areas in the Neotropical Savannah and the Amazon. Males have striking and unique adaptations on the wings, not known in any other insect. The wings are covered with wax nanocrystals that reflect ultraviolet light and infrared radiation. Furthermore, the wing membrane is permeated by an intricate system of tracheae, another unique trait in Insecta. We hypothesized that these adaptations might be important not only for intraspecific communication, but also for thermoregulation. We analysed male body and wing temperatures and compared them with another dragonfly with common translucent wings. The results suggest that the dorsal wing surface acts as a cooling system, whereas the ventral surface might serve to elevate body temperature. Therefore, we conclude that Z. lanei possesses adaptations that are unique in nature; a complex system of thermoregulation with the dual function of cooling down or elevating body temperature, depending on wing position. [ABSTRACT FROM AUTHOR]

The biodiversity–ecosystem function literature provides a useful framework to examine many processes associated with species diversity in ecology. One such context is the maintenance of biodiversity by facilitation in arid ecosystems.Here, we examined the complex interactions between local plant species richness and the intensity of shrub facilitation for maintaining biodiversity in arid plant communities.A synthesis including a meta‐analysis was used to compile nearly 600 papers on positive interactions mediated by shrubs in dryland plant communities (search terms: shrub, positive, facilitat*) to examine whether interactions in these studies changed with reported local species richness. A total of 19 studies and 141 independent instances directly examined and reported facilitation of diversity measures in naturally assembled plant communities and provided estimates of local species richness.Synthesis. The net effect of increasing local plant species richness was negative and shifted the relative frequency of interactions with shrubs from positive to negative with increasing local species richness. This relationship suggests that increases in richness do not always enhance functions that maintain diversity in plants communities likely due to concurrent increases in the indirect negative interactions between species under shrubs or in changes in the local species pool. [ABSTRACT FROM AUTHOR]

To chalk-out suitable management strategy for fluke infestation in sheep flocks, their prevalence was studied in two different agro-climatic regions of Rajasthan. From April, 2004 to March, 2018, a total of 89112 faecal samples were examined for flukes by sedimentation technique. An overall prevalence was maximum (6.08%) for Paramphistomum spp. followed by 0.19% for Schistosoma indicum and minimum (0.03%) for Fasciola gigantica. Prevalence of Paramphistomum spp. and S. indicum was significantly higher in semi-arid region (8.66 and 0.22%) compared to arid region (1.51 and 0.12%). The overall annual prevalence rates varied significantly from 1.69 to 9.70% for Paramphistomum spp, from 0.02 to 1.73% for S. indicum and from nil to 0.12% for F. gigantica. The prevalence of all the three flukes was found to be influenced significantly by month and season. For Paramphistomum spp, the overall monthly prevalence varied from 0.15% (Nov) to 16.60% (Jul). The seasonal prevalence was maximum during monsoon and minimum during winter. The occurrence of F. gigantica was sporadic in arid region as compared to regularity in semi-arid region. The monthly profile of S. indicum exhibited significantly higher prevalence (>0.20%) from May to August in arid region and from July to October in semi-arid region. A significant effect of agro-climatic region on prevalence of S. indicum was noticed only during monsoon season with higher incidence in semi-arid region (0.59%) as compared to arid region (0.25%). The study suggested that the fluke infections are present in endemic pattern in sheep flocks of Rajasthan (particularly in semi-arid region) and deserves serious attention. Therefore, it is important to obtain detail information on host parasite relationship and snail species which will aid for developing suitable control strategies. [ABSTRACT FROM AUTHOR]

Gaseous phase hydration properties for thalli of Niebla tigrina from Atacama Desert, and for Umbilicaria antarctica from Isla Robert, maritime Antarctica, were analyzed using 1H-NMR relaxometry, spectroscopy, and sorption isotherm analysis. The molecular dynamics of residual water was monitored to distinguish the sequential binding very tightly, tightly, and loosely bound water fractions. These two species differ in hydration kinetics faster for Desert N. tigrina [A1 = 0.51(4); t1 = 0.51(5) h, t2 = 15.0(1.9) h; total 0.7 for p/p0 = 100%], compared to Antarctic U. antarctica [A1 = 0.082(6), t1 = 2.4(2) h, t2 = [26.9(2.7)] h, total 0.6 for p/p0 = 100%] from humid polar area. The 1H-NMR measurements distinguish signal from tightly bound water, and two signals from loosely bound water, with different chemical shifts higher for U. antarctica than for N. tigrina. Both lichen species contain different amounts of water-soluble solid fraction. For U. antarctica, the saturation concentration of water soluble solid fraction, cs = 0.55(9), and the dissolution effect is detected at least up to Δm/m0 = 0.7, whereas for N. tigrina with the similar saturation concentration, cs = 053(4), this fraction is detected up to the threshold hydration level equal to ΔM/m0 = 0.3 only. [ABSTRACT FROM AUTHOR]

Positive interactions between shrubs and animals are frequent in desert ecosystems. Shrub canopies can provide refuge to some animal species from predators and shelter from stressful environmental conditions by ameliorating high temperatures through lowering the amplitude of variation. Consequently, there have been many contrasts of shrub versus open effects; however, we extend this approach further by testing these effects on a gradient of shrub densities in the Carrizo National Monument, California. We tested the hypothesis that shrub density is a landscape-level predictor of vertebrate community composition and structure. We used camera traps, transects and focal observations to estimate animal density and composition, alongside the deployment of temperature sensors. Plots were established within shrub patches ranging from 0 to 12 shrubs per 10 m radius. Plots with relatively higher shrub densities had increased abundance and richness of vertebrate animal species. Temperature and residual dry matter were also important mediators of animal density and richness. Shrub cover was also an important driver of animal communities but we propose that shrub density is a more rapid proxy for vegetation effects in deserts relevant to wildlife conservationists, and managers. [ABSTRACT FROM AUTHOR]

Positive interactions between shrubs and animals are frequent in desert ecosystems. Shrub canopies can provide refuge to some animal species from predators and shelter from stressful environmental conditions by ameliorating high temperatures through lowering the amplitude of variation. Consequently, there have been many contrasts of shrub versus open effects; however, we extend this approach further by testing these effects on a gradient of shrub densities in the Carrizo National Monument, California. We tested the hypothesis that shrub density is a landscape-level predictor of vertebrate community composition and structure. We used camera traps, transects and focal observations to estimate animal density and composition, alongside the deployment of temperature sensors. Plots were established within shrub patches ranging from 0 to 12 shrubs per 10 m radius. Plots with relatively higher shrub densities had increased abundance and richness of vertebrate animal species. Temperature and residual dry matter were also important mediators of animal density and richness. Shrub cover was also an important driver of animal communities but we propose that shrub density is a more rapid proxy for vegetation effects in deserts relevant to wildlife conservationists, and managers. [ABSTRACT FROM AUTHOR]

Aim: Non‐native invasive plants impact ecosystems globally, and the distributions of many species are expanding. The current and potential distributions of many invaders have not been characterized at the broad scales needed for effective management. We modelled the distributions of 15 non‐native invasive grass and forb species of concern in western North America to define their environmental niches and predict potential invasion risk. Location: Arid and semi‐arid western United States. Methods: We modelled species distribution using presence/absence data from > 148,000 vegetation survey plots to predict the probability of presence of each species based on associated climate, soil, topography and disturbance records. Boosted regression tree models were trained and tested within a buffer distance from presence observations of each species. Buffers were optimized by adding absence observations from increasingly large areas until prediction of presence was maximized, as defined by the area under the precision‐recall curve (AUPRC). We evaluated model AUPRC and other metrics by cross‐validation within training areas, then projected final models within focal EPA level III ecoregions. Results: Focal species were present in 2.7% to 21% of plots within model training areas of 40 to 340 km radius. Models conservatively estimated potential species presence, with typically low false positive rates and moderate sensitivity. The most influential predictors of presence included minimum temperature (especially for grasses), climatic water deficit, precipitation seasonality and fire history. Cold desert ecoregions were impacted by the most species, with predicted range expansion into the prairie ecoregions and infilling for Warm Desert species. Main conclusions: Invasive forb and grass species are likely to expand their ranges and continued increases in temperature, aridity and area burned will increase invasion risk. Monitoring species presence and absence and mapping known and potential ranges with a focus on presence detection, as in our methodology, will aid in identifying new invasions and prioritizing prevention and control. [ABSTRACT FROM AUTHOR]

In the ancient rock record, early replacement of metastable marine calcium carbonate deposits by dolomite has long been associated with evidence of arid depositional environments. Such associations led to the development of the seepage reflux dolomitization model, whereby magnesium‐rich marine waters concentrated by evaporation descend into underlying sediments, replacing primary aragonite and calcite deposits with dolomite through rock–water interaction. In the modern arid coastal systems of Qatar, where marine waters concentrate to halite saturation, both aqueous geochemical measurements and mineralogical investigations show that replacement of calcium carbonate deposits by dolomite is not occurring to any consequential degree. At best dolomite formation is minor and localized. Instead, modern and mid‐Holocene coastal deposits retain their original mineralogy, showing little evidence of carbonate precipitation reactions with the notable exception of beachrock formation. Pleistocene coastal deposits are mostly absent in comparison with both Qatar Holocene coastal deposits, and Pleistocene coastal deposits from more humid settings. The lack of onshore Pleistocene‐aged carbonate outcrops in Qatar, as well as regionally, is interpreted to reflect coastal sediment denudation during emergence due to: (i) the absence of coastal marine lithification; and (ii) the absence of meteoric cementation and root stabilization in the highly‐arid realm. In contrast, marine Palaeogene and Miocene carbonate deposits are preserved in outcrop in Qatar, having suffered marine lithification by dolomite, thus promoting retention of carbonate strata through subsequent lowstands. These older deposits formed during times of ocean acidification, which, based on natural system and laboratory investigations, is interpreted to promote metastable carbonate dissolution and dolomite formation. The highly‐arid Holocene and Pleistocene coastal systems of Qatar represent limestone factories, but these deposits are not being retained to the rock record. Based on these observations, the association between the occurrence of dolomite and arid depositional settings may be to some degree a preservation bias. [ABSTRACT FROM AUTHOR]

Positive interactions between shrubs and animals are frequent in desert ecosystems. Shrub canopies can provide refuge to some animal species from predators and shelter from stressful environmental conditions by ameliorating high temperatures through lowering the amplitude of variation. Consequently, there have been many contrasts of shrub versus open effects; however, we extend this approach further by testing these effects on a gradient of shrub densities in the Carrizo National Monument, California. We tested the hypothesis that shrub density is a landscape-level predictor of vertebrate community composition and structure. We used camera traps, transects and focal observations to estimate animal density and composition, alongside the deployment of temperature sensors. Plots were established within shrub patches ranging from 0 to 12 shrubs per 10 m radius. Plots with relatively higher shrub densities had increased abundance and richness of vertebrate animal species. Temperature and residual dry matter were also important mediators of animal density and richness. Shrub cover was also an important driver of animal communities but we propose that shrub density is a more rapid proxy for vegetation effects in deserts relevant to wildlife conservationists, and managers. [ABSTRACT FROM AUTHOR]

Woody plants in arid and semi-arid environments may enhance soil nutrient status, the so-called 'fertile island' effect, but this mechanism has never been tested in the drylands of New Zealand. In this study I investigated effects of Kunzea serotina, Discaria toumatou, Rosa rubiginosa, and Coprosma propinqua on soil properties in the drylands of central Otago, New Zealand. Soils had significantly higher organic matter under C. propinqua and significantly higher nitrate and phosphorus concentrations under K. serotina than soils in the adjacent open grassland. A bioassay using oat (Avena sativa) growth indicated higher fertility in soils from under K. serotina than from under grassland. A review of 28 other studies revealed that fertile island effects of woody plant species on soil nitrogen and phosphorus concentrations decreased significantly with increases in annual precipitation. The occurrence of fertile islands under only two of the four shrub species in the current study in a dry sub-humid environment is consistent with this trend of decreased fertile island effect with increased annual precipitation. The higher concentration of nitrogen in soils under woody plants such as C. propinqua may be explained by the plants depositing organic matter on the surface, but some species such as K. serotina, D. toumatou, R. rubiginosa and C. propinqua, may also preferentially establish in areas of high soil phosphorus availability. I conclude that the occurrence of fertile islands under woody plants may be due to both effects of the woody plant canopy, and the plants preferentially establishing in areas of high soil fertility. [ABSTRACT FROM AUTHOR]

Many terrestrial endotherm food webs constitute three trophic level cascades. Others have two trophic level dynamics (food limited herbivores; plants adapted to tackle intense herbivory) or one trophic level dynamic (herbivorous endotherms absent, thus plants compete for the few places where they can survive and grow). According to the Exploitation Ecosystems Hypothesis (EEH), these contrasting dynamics are consequences of differences in primary productivity. The productivity thresholds for changing food web dynamics were assumed to be global constants. We challenged this assumption and found that several model parameters are sensitive to the contrast between persistently warm and seasonally cold climates. In persistently warm environments, three trophic level dynamics can be expected to prevail almost everywhere, save the most extreme deserts. We revised EEH accordingly and tested it by compiling direct evidence of three and two trophic level dynamics and by studying the global distribution of felids. In seasonally cold environments, we found evidence for three trophic level dynamics only in productive ecosystems, while evidence for two trophic level dynamics appeared in ecosystems with low primary productivity. In persistently warm environments, we found evidence for three trophic level dynamics in all types of ecosystems. The distribution of felids corroborated these results. The empirical evidence thus indicates that two trophic level dynamics, as defined by EEH, are restricted to seasonally cold biomes with low primary productivity, such as the artic–alpine tundra and the temperate steppe. [ABSTRACT FROM AUTHOR]

Biological soil crusts (biocrusts) and arbuscular mycorrhizal (AM) fungi are communities of soil organisms often targeted to assist in the achievement of multiple ecological restoration goals. In drylands, benefits conferred from biocrust and AM fungal inoculation, such as improved native plant establishment and soil stabilization, have primarily been studied separately. However, comparisons between these two types of soil inoculants and investigations into potential synergies between them, particularly at the plant community scale, are needed to inform on‐the‐ground management practices in drylands. We conducted two full‐factorial experiments—one in greenhouse mesocosms and one in field plots—to test the effects of AM fungal inoculation, biocrust inoculation, and their interaction on multiple measures of dryland restoration success. Biocrust inoculation promoted soil stabilization and plant drought tolerance, but had mixed effects on native plant diversity (positive in greenhouse, neutral in field) and productivity (negative in greenhouse, neutral in field). In greenhouse mesocosms, biocrust inoculation reduced plant biomass, which was antagonistic to % root length colonized by AM fungi. Inoculation with native or commercial AM fungi did not influence plant establishment, drought tolerance, or soil stabilization in either study, and few synergistic effects of simultaneous inoculation of AM fungi and biocrusts were observed. These results suggest that, depending on the condition of existing soil communities, inoculation with AM fungi may not be necessary to promote dryland restoration goals, while inoculation with salvaged biocrust inoculation may be beneficial in some contexts. [ABSTRACT FROM AUTHOR]

Aims: Soil respiration (Rs) is a major pathway for carbon release to the atmosphere. We explored variability in dryland Rs response to rainfall pulses at multiple levels of spatial heterogeneity: 1) along a hyper-arid to arid rainfall gradient, 2) across soil surfaces that differ in stability and composition, and 3) among different geomorphic and vegetation patch types. Methods: We measured in situ Rs responses for 48 h following simulated rainfall pulses in the Namib Desert. Working across the rainfall gradient, we compared Rs responses on two soil surfaces. Each soil surface had two vegetation/geomorphic patch types that differed in organic matter sources and transport processes, with one characterized by depositional inputs and one characterized by erosional losses. Results: Soil respiration was highly responsive to rainfall pulses, although soil surfaces and patch types often exerted more control on Rs than did rainfall pulses. Rainfall generally had proportionally greater influence on Rs with higher annual rainfall. Greater Rs occurred on stable than unstable soil surfaces and in depositional than erosional patch types. Conclusions: Large differences in Rs among rainfall zones, soil surfaces, and patch types point to the need to carefully consider multiple scales of spatial heterogeneity when interpreting dryland biogeochemical fluxes. [ABSTRACT FROM AUTHOR]