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There are significant and on-going issues faced by the U.S. Army Corps of Engineers and other federal agencies in regulating and affording protections to arid non-perennial stream resources in western arid regions of the U.S. (i.e., Arid West). The significance of these issues is magnified by the large portion of dryland areas situated within the U.S., as well as worldwide, where non-perennial streams also comprise most of the stream types. It is essential for politicians, decision makers, and those assessing and managing aquatic resources to be aware of the current body of understanding available on these important resources. An in-depth literature and geospatial analysis was conducted on arid non-perennial stream functions as they relate to key climate ecosystem controls, influential environmental parameter controls, and hydrology (e.g., streamflow regime) forcing functions at various landscape scales and settings. Out of the overall stream function categories of Biogeochemical, Habitat, Hydrology, Sediment, Biodiversity, Energy Dissipation, and Connectivity examined within global and U.S. literature, only Biogeochemical, Habitat, Hydrology, Sediment emerged as the primary function categories of study focus. Global and U.S. data followed similar overall trends with generally a higher coverage of Habitat functions above all other function categories, which was unexpected given the higher importance of Hydrology and Sediment within the overall hierarchy of influences among stream function categories. Other similar overall trends within global and U.S. data included higher occurrences within cold steppe subclimes, steppe precipitation areas, and ephemeral streams. Of the three environmental parameters (watershed position, stream planform type, and riverine corridor sampling location type) analyzed, these patterns tended to be more consistent when compared across watershed positions, with generally more deviation when viewed through the lenses of stream planform types

Climate change effects on host–parasite interactions have been poorly studied in arid or semi-arid habitats. Here, we conducted an experiment aimed to increase the temperature inside European roller Coracias garrulus nest boxes located in a semi-arid habitat on different nest-site types to look for effects on different ectoparasite abundances and nestling growth. Average nest temperature was slightly higher in heated nests than in control nests, although differences were not statistically significant. However, relative humidity was significantly lower at night in heated nests as compared to control nests. The abundance of sand flies, mites and carnid flies was significantly higher in heated, less humid, nests while biting midge abundance was significantly lower in heated nests. Other ectoparasites were not significantly affected by treatment. Relative humidity was high even in heated nests, reaching more than 60%. Sand fly abundance was higher in nests located in sandstone walls, while mite abundance was higher in isolated farmhouses. In addition, sand fly prevalence was higher in nests located in isolated farmhouses and sandstone walls. Heat treatment, nest-site type or ectoparasite abundances did not affect the nestling body mass, wing length or their growth at different nestling ages.

Water scarcity is a problem not only in the Tarim river but worldwide. Starting from water scarcity in the upper reaches of the Tarim River, this research focuses on exploring the possible solution for water scarcity and unsustainable livelihood for farmers in this region. By referring to similar cases and literature, principles of water-saving, afforestation, and new circularity were concluded to solve those problems. During the design process, the possibility of the upper reaches of the Tarim River was explored by the method of logical system and mapping. This project brings a new water system, farming method, and forest to this region and by those new elements could formulate a new solid circularity. In this design-based research, solutions for water scarcity and sustainable livelihood are explored, experimented , and achieved in the upper reaches of the Tarim River., Architecture, Urbanism and Building Sciences | Landscape Architecture

The water quality of urban runoff is significant to arid and semiarid regions, such assouthern Arizona, which count urban runoff among the limited renewable resources for a continued water supply. Despite the essential nature of this resource, the hydrochemical evolution of urban runoff over the course of a storm and a rainy season overall is less well understood. Improved understanding would help researchers and resource managers alike in addressing water quality issues. Nitrogen species constitute a high priority water quality concern. This research addresses the evolution and transport of nitrogen during eight individual storm events that occurred over three summer monsoon seasons (2016-2018) in an urban catchment in the semiarid city of Tucson, Arizona. Hysteretic storm behavior was analyzed for the solute concentrations of nitrogen species and a conservative tracer (Cl-) to provide insight into the catchment processes between the upstream and downstream sampling locations. Of the 94 performed analyses, 49 hysteresis analyses display clockwise behavior. Thirty-six analyses result in counterclockwise loops, and 9 are linear (i.e., no hysteresis). All 9 of the linear responses are total organic nitrogen (TON). In general, the upstream site has a more consistent clockwise response, and the downstream site has a more varied response among the measured solutes. The results indicate that solute flushing is the primary response of the gravel lined urban wash during monsoon events, with some complexity in the response resulting from limited biogeochemical processing and/or additional runoff/solute sources resulting from the managed nature of the watershed. The linear TON response of many storms indicates that the nitrogen species moving through the system are inorganic. The downstream site displays more varied hysteresis responses due to the presence of a concrete lined section of the channel under a two- lane residential road, which increases the discharge rate and alt

The water quality of urban runoff is significant to arid and semiarid regions, such assouthern Arizona, which count urban runoff among the limited renewable resources for a continued water supply. Despite the essential nature of this resource, the hydrochemical evolution of urban runoff over the course of a storm and a rainy season overall is less well understood. Improved understanding would help researchers and resource managers alike in addressing water quality issues. Nitrogen species constitute a high priority water quality concern. This research addresses the evolution and transport of nitrogen during eight individual storm events that occurred over three summer monsoon seasons (2016-2018) in an urban catchment in the semiarid city of Tucson, Arizona. Hysteretic storm behavior was analyzed for the solute concentrations of nitrogen species and a conservative tracer (Cl-) to provide insight into the catchment processes between the upstream and downstream sampling locations. Of the 94 performed analyses, 49 hysteresis analyses display clockwise behavior. Thirty-six analyses result in counterclockwise loops, and 9 are linear (i.e., no hysteresis). All 9 of the linear responses are total organic nitrogen (TON). In general, the upstream site has a more consistent clockwise response, and the downstream site has a more varied response among the measured solutes. The results indicate that solute flushing is the primary response of the gravel lined urban wash during monsoon events, with some complexity in the response resulting from limited biogeochemical processing and/or additional runoff/solute sources resulting from the managed nature of the watershed. The linear TON response of many storms indicates that the nitrogen species moving through the system are inorganic. The downstream site displays more varied hysteresis responses due to the presence of a concrete lined section of the channel under a two- lane residential road, which increases the discharge rate and alt

Water scarcity is a problem not only in the Tarim river but worldwide. Starting from water scarcity in the upper reaches of the Tarim River, this research focuses on exploring the possible solution for water scarcity and unsustainable livelihood for farmers in this region. By referring to similar cases and literature, principles of water-saving, afforestation, and new circularity were concluded to solve those problems. During the design process, the possibility of the upper reaches of the Tarim River was explored by the method of logical system and mapping. This project brings a new water system, farming method, and forest to this region and by those new elements could formulate a new solid circularity. In this design-based research, solutions for water scarcity and sustainable livelihood are explored, experimented , and achieved in the upper reaches of the Tarim River., Architecture, Urbanism and Building Sciences | Landscape Architecture

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.

Globally, it is expected that arid and semi-arid areas will face increasing frequency of drought through the 21st century. Drought is normally attributed to climatic factors. However, humans constantly alter hydrologic systems through manipulating and consuming water, which can also cause drought. However, human influence on drought, outside of influences on warming-driven climate change, is rarely studied. Here, the upper Colorado River Basin (Texas) is studied to assess the human influence on drought conditions in a semi-arid basin. An observation-modeling framework is used to simulate naturalized runoff conditions which are compared to observed data in an undisturbed (little human influence) and disturbed (much human influence) period to elucidate human influences on drought. Further, public water storage and supply data are incorporated to analyze how human water management may be specifically affecting downstream hydrologic drought in the upper Colorado River Basin. Results show that according to observed data, drought occurred more often, persisted longer on average, and had a higher maximum duration during the disturbed period. Naturalized model output did not predict such increases, indicating that human influence is responsible. Water deliveries in the study area were found to significantly affect downstream flow and are connected to instances of human-influenced drought. Results suggest that in order to reduce downstream drought conditions, deliveries will likely have to be reduced and that reducing deliveries during periods of low rainfall, or during months in which deliveries constitute a large portion of human influenced drought severity could be especially helpful in alleviating downstream drought.

Land conversion across the Southwestern U.S. for agricultural and livestock use and prolonged drought conditions cascade to reduce ecosystem function, including habitat provision for wildlife. Arroyo restoration efforts aim to improve wildlife habitat by decreasing soil erosion and enhancing water retention. These hydrologic and geomorphic changes increase the likelihood that wildlife use restored corridors by increasing riparian vegetation cover. Rio Mora National Wildlife Refuge (RMNWR) has restored several arroyos by installing a system of one-rock dams throughout the refuge, but the extent to which mammals prefer restored over unrestored riparian corridors and how habitat structure influences mammalian use and density in those corridors is unknown. To test whether arroyo restoration improves habitat for large mammals, we collected data on corridor morphology and vegetation structure in the vicinity of 30 camera traps along 10 corridors within the RMNWR. Habitat variability across camera traps was driven by corridor level differences in water availability, vegetation composition, and morphology, rather than restoration status. A total of fifteen species were recorded using two of the ten canyons. Mean species abundance differed only for three species that were found in one canyon versus another, while mean species occurrence showed a greater difference for nine of the fifteen species. Habitat structure effects tended to relate modestly to visitation rates.

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.

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.

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.

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.

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.

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.

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.

Globally, it is expected that arid and semi-arid areas will face increasing frequency of drought through the 21st century. Drought is normally attributed to climatic factors. However, humans constantly alter hydrologic systems through manipulating and consuming water, which can also cause drought. However, human influence on drought, outside of influences on warming-driven climate change, is rarely studied. Here, the upper Colorado River Basin (Texas) is studied to assess the human influence on drought conditions in a semi-arid basin. An observation-modeling framework is used to simulate naturalized runoff conditions which are compared to observed data in an undisturbed (little human influence) and disturbed (much human influence) period to elucidate human influences on drought. Further, public water storage and supply data are incorporated to analyze how human water management may be specifically affecting downstream hydrologic drought in the upper Colorado River Basin. Results show that according to observed data, drought occurred more often, persisted longer on average, and had a higher maximum duration during the disturbed period. Naturalized model output did not predict such increases, indicating that human influence is responsible. Water deliveries in the study area were found to significantly affect downstream flow and are connected to instances of human-influenced drought. Results suggest that in order to reduce downstream drought conditions, deliveries will likely have to be reduced and that reducing deliveries during periods of low rainfall, or during months in which deliveries constitute a large portion of human influenced drought severity could be especially helpful in alleviating downstream drought.

Arid and semi-arid ecosystems are characterized by patchy vegetation and variable resource availability. The interplant spaces of these ecosystems are very often covered by cyanobacteria-dominated biocrusts, which are the primary colonizers of terrestrial ecosystems and key in facilitating the succession of other biocrust organisms and plants. Cyanobacterial biocrusts regulate the horizontal and vertical fluxes of water, carbon and nutrients into and from the soil and play crucial hydrological, geomorphological and ecological roles in these ecosystems. In this paper, we analyze the influence of cyanobacterial biocrusts on water balance components (infiltration-runoff, evaporation, soil moisture and non-rainfall water inputs (NRWIs)) in representative semiarid ecosystems in southeastern Spain. The influence of cyanobacterial biocrusts, in two stages of their development, on runoff-infiltration was studied by rainfall simulation and in field plots under natural rainfall at different spatial scales. Results showed that cover, exopolysaccharide content, roughness, organic carbon, total nitrogen, available water holding capacity, aggregate stability, and other properties increased with the development of the cyanobacterial biocrust. Due to the effects on these soil properties, runoff generation was lower in well-developed than in incipient-cyanobacterial biocrusts under both simulated and natural rainfall and on different spatial scales. Runoff yield decreased at coarser spatial scales due to re-infiltration along the hillslope, thus decreasing hydrological connectivity. Soil moisture monitoring at 0.03 m depth revealed higher moisture content and slower soil water loss in plots covered by cyanobacterial biocrusts compared to bare soils. Non-rainfall water inputs were also higher under well-developed cyanobacterial biocrusts than in bare soils. Disturbance of cyanobacterial biocrusts seriously affected the water balance by increasing runoff, decreasing soil moisture and

We lack a defined suite of attributes that allow us to universally predict the distribution of bacterial diversity across and within globally distributed biomes. Using data from a global survey, including 237 locations and multiple environmental predictors, we found that only ultraviolet light, forest environments, soil carbon and pH can be considered as significant and globally consistent predictors of soil bacterial diversity, valid within and across biomes (arid, temperate and continental). Bacterial diversity always peaked in grasslands, with moderate-to-low carbon and ultraviolet light levels, and high soil pH. Using these environmental data, we generated the first global predictive map of the distribution of soil bacterial diversity. Our work helps to identify a unique set of environmental attributes for universally predicting the distribution of soil bacterial diversity. This knowledge is key to help predict changes in ecosystem functioning and the provision of essential services under changing environments.

The zodariine spider genus Mallinus Simon, 1893 is redescribed and diagnosed. The type species, M. nitidiventris Simon, 1893 from South Africa, was originally described from subadult specimens. Adults of both sexes of M. nitidiventris are described for the first time, based on recently collected material, and the genus is rediagnosed, redescribed, and its relationships discussed. A single aberrant male specimen from Namibia is here described as a morphospecies, as it is presumed to only be superficially related. A second species, M. defectus Strand, 1906 from Tunisia, is considered a ‘species inquirenda’, as the type specimens could not be traced, but this species is in any case unlikely to be congeneric. The genus is one of 10 cases of a monotypic genus in the Zodariidae. Notes are provided on the biology of M. nitidiventris.

This study investigates the fire regime for the arid Carnarvon Basin region of Western Australia using remotely sensed imagery. A fire history database was constructed from satellite images to characterise the general fire regime and determine any effect of vegetation types and pre-fire weather and climate. The study area was divided into two sections (northern and southern) due to their inherently different vegetation and climate. A total of 23.8% (15,646 km2) of the study area was burnt during the 39-year study period. Heathland vegetation (54%) burnt the most extensively in the southern study area, and hummock grasslands (68%) in the northern. A single, unusually large fire in 2012 followed exceptional rains in the previous 12 months and accounted for 55% of the total burnt area. This fire burnt mainly through Acacia shrublands and woodlands rather than hummock grasslands, as normally experienced in the northern study area. Antecedent rainfall and fire weather were found to be the main meteorological factors driving fire size. Both study areas showed a moderate to strong correlation between fire size and increased pre-fire rainfall in the year preceding the fire. Predicted future changes in climate may lead to more frequent and higher intensity fires.

Studying nomadic animal movement across species and ecosystems is essential for better understanding variability in nomadism. In arid environments, unpredictable changes in water and forage resources are known drivers of nomadic movements. Water resources vary temporally but are often spatially stationary, whereas foraging resources are often both temporally and spatially variable. These differences may lead to different types of nomadic movements: forage‐ vs. water‐driven nomadism. Our study investigates these two different types of nomadism in relation to resource gradients from mesic steppe to xeric desert environments in Mongolia's Gobi‐Steppe Ecosystem. We hypothesized that in the desert, where water is a key resource, animals are more water‐dependent and may show water‐driven nomadism with frequent revisits to spatially fixed resources, while in the steppe, animals are less water‐dependent and may show forage‐driven nomadism, tracking high‐quality foraging patches with infrequent revisits to previously used resources. We utilized GPS movement data from 40 individuals of four ungulate species (Mongolian gazelle, goitered gazelle, saiga antelope, and Asiatic wild ass) in the Gobi‐Steppe Ecosystem. We calculated displacement distances and recursion metrics and subsequently performed a principal component analysis to quantify the variation in movement patterns. The satellite‐derived vegetation greenness served as a proxy for the resource gradient and was associated with variation in movement behaviors described by the first principal component, demonstrating that the variability in movements was closely related to the resource gradient from mesic to xeric habitats. We showed that ungulates in the resource‐rich steppe tended to move long distances with few revisits (forage‐driven nomadism), while ungulates in the resource‐poor desert tended to move shorter distances with more revisits (water‐driven nomadism). Our results suggest that xeric and mesic habitats promot

Studying nomadic animal movement across species and ecosystems is essential for better understanding variability in nomadism. In arid environments, unpredictable changes in water and forage resources are known drivers of nomadic movements. Water resources vary temporally but are often spatially stationary, whereas foraging resources are often both temporally and spatially variable. These differences may lead to different types of nomadic movements: forage‐ vs. water‐driven nomadism. Our study investigates these two different types of nomadism in relation to resource gradients from mesic steppe to xeric desert environments in Mongolia's Gobi‐Steppe Ecosystem. We hypothesized that in the desert, where water is a key resource, animals are more water‐dependent and may show water‐driven nomadism with frequent revisits to spatially fixed resources, while in the steppe, animals are less water‐dependent and may show forage‐driven nomadism, tracking high‐quality foraging patches with infrequent revisits to previously used resources. We utilized GPS movement data from 40 individuals of four ungulate species (Mongolian gazelle, goitered gazelle, saiga antelope, and Asiatic wild ass) in the Gobi‐Steppe Ecosystem. We calculated displacement distances and recursion metrics and subsequently performed a principal component analysis to quantify the variation in movement patterns. The satellite‐derived vegetation greenness served as a proxy for the resource gradient and was associated with variation in movement behaviors described by the first principal component, demonstrating that the variability in movements was closely related to the resource gradient from mesic to xeric habitats. We showed that ungulates in the resource‐rich steppe tended to move long distances with few revisits (forage‐driven nomadism), while ungulates in the resource‐poor desert tended to move shorter distances with more revisits (water‐driven nomadism). Our results suggest that xeric and mesic habitats promot

Studying nomadic animal movement across species and ecosystems is essential for better understanding variability in nomadism. In arid environments, unpredictable changes in water and forage resources are known drivers of nomadic movements. Water resources vary temporally but are often spatially stationary, whereas foraging resources are often both temporally and spatially variable. These differences may lead to different types of nomadic movements: forage‐ vs. water‐driven nomadism. Our study investigates these two different types of nomadism in relation to resource gradients from mesic steppe to xeric desert environments in Mongolia's Gobi‐Steppe Ecosystem. We hypothesized that in the desert, where water is a key resource, animals are more water‐dependent and may show water‐driven nomadism with frequent revisits to spatially fixed resources, while in the steppe, animals are less water‐dependent and may show forage‐driven nomadism, tracking high‐quality foraging patches with infrequent revisits to previously used resources. We utilized GPS movement data from 40 individuals of four ungulate species (Mongolian gazelle, goitered gazelle, saiga antelope, and Asiatic wild ass) in the Gobi‐Steppe Ecosystem. We calculated displacement distances and recursion metrics and subsequently performed a principal component analysis to quantify the variation in movement patterns. The satellite‐derived vegetation greenness served as a proxy for the resource gradient and was associated with variation in movement behaviors described by the first principal component, demonstrating that the variability in movements was closely related to the resource gradient from mesic to xeric habitats. We showed that ungulates in the resource‐rich steppe tended to move long distances with few revisits (forage‐driven nomadism), while ungulates in the resource‐poor desert tended to move shorter distances with more revisits (water‐driven nomadism). Our results suggest that xeric and mesic habitats promot

This study investigates the fire regime for the arid Carnarvon Basin region of Western Australia using remotely sensed imagery. A fire history database was constructed from satellite images to characterise the general fire regime and determine any effect of vegetation types and pre-fire weather and climate. The study area was divided into two sections (northern and southern) due to their inherently different vegetation and climate. A total of 23.8% (15,646 km2) of the study area was burnt during the 39-year study period. Heathland vegetation (54%) burnt the most extensively in the southern study area, and hummock grasslands (68%) in the northern. A single, unusually large fire in 2012 followed exceptional rains in the previous 12 months and accounted for 55% of the total burnt area. This fire burnt mainly through Acacia shrublands and woodlands rather than hummock grasslands, as normally experienced in the northern study area. Antecedent rainfall and fire weather were found to be the main meteorological factors driving fire size. Both study areas showed a moderate to strong correlation between fire size and increased pre-fire rainfall in the year preceding the fire. Predicted future changes in climate may lead to more frequent and higher intensity fires.

Severe drought driven by climate change and water use by humans are causing formerly perennial streams to flow intermittently, presenting an unprecedented level of disturbance. The loss of emerging aquatic insects as potential prey items could negatively impact riparian and terrestrial species, including lizards. Because lizards play important roles in riparian food webs (e.g. predators, nutrient cycling), it is crucial to understand the cascading effects of stream drying on lizard communities. We hypothesized that perennial streams provide aquatic subsidies to riparian lizards, reducing competition and opening niches. We predicted that lizard abundances would be greater, and that individuals within a species would grow larger and faster, along perennial streams compared to ephemeral streams. We studied three paired 100-meter perennial and ephemeral reaches with similar microhabitat but differing water availability in the Chiricahua Mountains of southeastern Arizona. We measured individual growth rates during a 2-month mark-recapture study of Yarrow’s spiny lizards (Sceloporus jarrovii), striped plateau lizards (Sceloporus virgatus), and ornate tree lizards (Urosaurus ornatus). We used emergence traps to quantify the availability of aquatic prey. Aquatic insects were collected in high abundances, suggesting a potential food source for lizards along perennial streams that may be unavailable along ephemeral streams. When considering mass at first capture, we found that S. jarrovii were larger at perennial versus ephemeral reaches. However, this pattern did not hold true for S. virgatus. Additionally, we failed to detect differences in abundances between paired perennial and ephemeral reaches for either S. jarrovii or S. virgatus. Low sample sizes prevented us from performing any statistical analyses for Urosaurus ornatus and on the mark-recapture data for S. jarrovii and S. virgatus. Although more research is needed to confirm these results, they indicate that emergin

Bare soils and grasslands in arid and semi-arid conditions constitute a large portion of the earth surface. Evaporation, which is the main component of the water balance in these conditions, often takes place through a dry soil layer (DSL). There is no scientific agreement yet on the DSL effects on evaporation rates. The implementations of three conceptual models of DSL-evaporation were tested for the simulation of evaporation rates in a semi-arid study area in Central Spain: (i) the daily-average model, based on the assumption that the daily average vapour transport in a DSL can be represented in analogy to isothermal liquid flow; (ii) the numerical model solving the Richards equation, in this case HYDRUS1D was used; and (iii) the pore-scale model, based on soil column experiments in laboratory conditions. The evaporation rates estimated by the three conceptual models for semi-arid field conditions were compared with the evaporation rates measured by an eddy covariance tower in the same area. The results indicate that the daily-average conceptual model assumption, in which the DSL has no effects on evaporation, does not hold in very dry conditions. The numerical model solving the Richards equation was not able to simulate the effects of the DSL on evaporation rates. The evaporation estimates obtained by the pore-scale conceptual model were closest to the eddy covariance measurements during the dry season, however this model was applicable only to the relatively steady evaporation conditions during afternoons and only assuming spatially constant DSL thickness.

Severe drought driven by climate change and water use by humans are causing formerly perennial streams to flow intermittently, presenting an unprecedented level of disturbance. The loss of emerging aquatic insects as potential prey items could negatively impact riparian and terrestrial species, including lizards. Because lizards play important roles in riparian food webs (e.g. predators, nutrient cycling), it is crucial to understand the cascading effects of stream drying on lizard communities. We hypothesized that perennial streams provide aquatic subsidies to riparian lizards, reducing competition and opening niches. We predicted that lizard abundances would be greater, and that individuals within a species would grow larger and faster, along perennial streams compared to ephemeral streams. We studied three paired 100-meter perennial and ephemeral reaches with similar microhabitat but differing water availability in the Chiricahua Mountains of southeastern Arizona. We measured individual growth rates during a 2-month mark-recapture study of Yarrow’s spiny lizards (Sceloporus jarrovii), striped plateau lizards (Sceloporus virgatus), and ornate tree lizards (Urosaurus ornatus). We used emergence traps to quantify the availability of aquatic prey. Aquatic insects were collected in high abundances, suggesting a potential food source for lizards along perennial streams that may be unavailable along ephemeral streams. When considering mass at first capture, we found that S. jarrovii were larger at perennial versus ephemeral reaches. However, this pattern did not hold true for S. virgatus. Additionally, we failed to detect differences in abundances between paired perennial and ephemeral reaches for either S. jarrovii or S. virgatus. Low sample sizes prevented us from performing any statistical analyses for Urosaurus ornatus and on the mark-recapture data for S. jarrovii and S. virgatus. Although more research is needed to confirm these results, they indicate that emergin

Sediment-routing systems continuously transfer information and mass from eroding source areas to depositional sinks. Understanding how these systems alter environmental signals is critical when it comes to inferring source-area properties from the sedimentary record. We measure cosmogenic 10Be and 26Al along three large sediment-routing systems ( ∼ 100 000 km2) in central Australia with the aim of tracking downstream variations in 10Be-26Al inventories and identifying the factors responsible for these variations. By comparing 56 new cosmogenic 10Be and 26Al measurements in stream sediments with matching data (n = 55) from source areas, we show that 10Be-26Al inventories in hillslope bedrock and soils set the benchmark for relative downstream modifications. Lithology is the primary determinant of erosion-rate variations in source areas and despite sediment mixing over hundreds of kilometres downstream, a distinct lithological signal is retained. Post-orogenic ranges yield catchment erosion rates of ∼ 6-11 m Myr−1 and silcrete-dominant areas erode as slow as ∼ 0.2 m Myr−1. 10Be-26Al inventories in stream sediments indicate that cumulative-burial terms increase downstream to mostly ∼ 400-800 kyr and up to ∼ 1.1 Myr. The magnitude of the burial signal correlates with increasing sediment cover downstream and reflects assimilation from storages with long exposure histories, such as alluvial fans, desert pavements, alluvial plains, and aeolian dunes. We propose that the tendency for large alluvial rivers to mask their 10Be-26Al source-area signal differs according to geomorphic setting. Signal preservation is favoured by (i) high sediment supply rates, (ii) high mean runoff, and (iii) a thick sedimentary basin pile. Conversely, signal masking prevails in landscapes of (i) low sediment supply and (ii) juxtaposition of sediment storages with notably different exposure histories.

Wetlands in arid and semi-arid regions are complex fragile ecosystems that are critical in maintaining and controlling environmental quality and biodiversity. These wetlands and specially closed lake systems depend on support processes in upstream parts of the basin or recharge zone, as small changes in river flow regime can cause significant changes in lake level, salinity and productivity. Recent strong alterations in river flow regimes due to climate and land use change have resulted in ecosystem degradation and desiccation of many saline lakes in arid and semi-arid regions. Because of the low economic value of these lakes, their hydrology has not been monitored accurately, making it difficult to determine water balance and assess the role of water use and climate in lake desiccation. Furthermore, available data are usually of coarse resolution on both spatial and temporal scale. New frameworks using all available data and refining existing information on lake basins were developed in this thesis to assess regional differences in water resource availability, impacts of human activities on river flow regime alteration and agricultural land use change. The frameworks were applied to study causes and impacts of desiccation of a major lake, Lake Urmia, one of the largest saltwater lakes on Earth. This highly endangered ecosystem is on the brink of a major environmental disaster resembling that around the Aral Sea. The spatial pattern of precipitation across the Lake Urmia basin was investigated, to shed light on regional differences in water availability. Using large numbers of rainfall records and a wide array of statistical descriptors, precipitation across space and time was evaluated. Another important research component involved examining streamflow records for headwaters and lowland reaches of the Lake Urmia basin, in order to determine whether observed changes are mainly due to climate change or anthropogenic activities (e.g. water withdrawal for domes, Tiivistelmä Kuivilla aridisilla ja semiaridisilla alueilla sijaitsevat kosteikot ovat hauraita ekosysteemejä. Ne ovat myös tavallista tärkeämpiä, koska ne ylläpitävät ja säätelevät ympäristön laatua sekä luonnon monimuotoisuutta. Nämä kosteikot, kuten valtaosa muistakin kosteikoista, ovat riippuvaisia vesistöalueen ylemmillä osilla tehdyistä toimista kuten vesistöjen säännöstelystä. Jopa pienet muutokset jokien virtauksissa voivat aiheuttaa merkittäviä muutoksia järvien vedenpinnan korkeuteen, suolapitoisuuteen ja tuottavuuteen. Viimeaikaiset ilmastonmuutoksen ja maankäytön muutosten aiheuttamat voimakkaat muutokset jokien virtaamiin ovat johtaneet ekosysteemien rappeutumiseen sekä monien suolajärvien kuivumiseen kuivilla ja puolikuivilla alueilla. Kuivilla alueilla sijaitsevien suolajärvien hydrologiaa ei ole tarkkailtu riittävästi niiden alhaisemman taloudellisen arvon vuoksi. Se hankaloittaa vesitaseen määrittämistä. Tarkkojen tietojen puuttuessa on vaikea arvioida myös sitä, miten vedenkäyttö ja ilmasto ovat vaikuttaneet järvien kuivumiseen. Lisäksi saatavilla olevat tiedot ovat yleensä sekä ajallisesti että alueellisesti epätarkkoja. Analysointiin tarvittavien tietojen ja välineiden puute saattaa pahimmillaan johtaa ristiriitaisiin oletuksiin. Väitöstyön päätavoite on tarjota puitteet, joilla parannetaan ymmärrystä vesivarojen alueellisista eroista, ihmisen toiminnan vaikutuksista jokien virtausten muutoksiin ja maatalouden maankäytön muutoksista käyttäen kaikkea saatavilla olevaa dataa sekä täsmentäen samalla vesistöistä jo olemassa olevaa tietoa. Väitöskirja tutkii yhden suuren järven kuivumisen syitä ja seurauksia. Urmiajärvi on yksi maapallon suurimmista suolajärvistä sekä erittäin uhanalainen ekosysteemi. Järvi on samankaltaisen ympäristökatastrofin partaalla, joka aiheutti Araljärven kuivumisen. Väitöskirja antaa tietoa veden saatavuuden alueellisista eroista tutkimalla sademäärien alueellista jakautumista Urmiajärven valuma-alueella. Tutkielmassa arvioid

Sediment-routing systems continuously transfer information and mass from eroding source areas to depositional sinks. Understanding how these systems alter environmental signals is critical when it comes to inferring source-area properties from the sedimentary record. We measure cosmogenic 10Be and 26Al along three large sediment-routing systems ( ∼ 100 000 km2) in central Australia with the aim of tracking downstream variations in 10Be-26Al inventories and identifying the factors responsible for these variations. By comparing 56 new cosmogenic 10Be and 26Al measurements in stream sediments with matching data (n = 55) from source areas, we show that 10Be-26Al inventories in hillslope bedrock and soils set the benchmark for relative downstream modifications. Lithology is the primary determinant of erosion-rate variations in source areas and despite sediment mixing over hundreds of kilometres downstream, a distinct lithological signal is retained. Post-orogenic ranges yield catchment erosion rates of ∼ 6-11 m Myr−1 and silcrete-dominant areas erode as slow as ∼ 0.2 m Myr−1. 10Be-26Al inventories in stream sediments indicate that cumulative-burial terms increase downstream to mostly ∼ 400-800 kyr and up to ∼ 1.1 Myr. The magnitude of the burial signal correlates with increasing sediment cover downstream and reflects assimilation from storages with long exposure histories, such as alluvial fans, desert pavements, alluvial plains, and aeolian dunes. We propose that the tendency for large alluvial rivers to mask their 10Be-26Al source-area signal differs according to geomorphic setting. Signal preservation is favoured by (i) high sediment supply rates, (ii) high mean runoff, and (iii) a thick sedimentary basin pile. Conversely, signal masking prevails in landscapes of (i) low sediment supply and (ii) juxtaposition of sediment storages with notably different exposure histories.

Knowledge about vegetation patterns along disturbance gradients is essential for conservation and management of coastal habitats in arid regions. This study focuses on the floristic diversity and the factors controlling the vegetation structure in the Gulf of Gabès (Tunisia). For this purpose, the floristic diversity of 120 relevés belonging to three coastal sites with different disturbance levels (40 relevés per site) was analyzed in relation with 10 environmental and anthropogenic factors. Therophytes constitute 54% of the 237 plants species belonging to 44 families identified in the present study. The species richness and floristic diversity indices exhibited a similar trend and peaked in the slightly disturbed site (H′ = 3.38; S = 176). The similarity between sites was relatively low and reached its maximum between the little and the highly disturbed sites. Two-way indicator species analysis and detrended correspondence analysis applied on the floristic data resulted in groups mainly determined by disturbance level by explicitly segregating the three sites. Canonical correspondence analysis (CCA) indicated that the spatial pattern of species composition was mainly influenced by anthropogenic variables. Partial CCA revealed that the effect of anthropogenic variables on floristic composition was thrice higher than the effect of environmental variables (57.5% vs. 18.4%, respectively). Overall, this study provides a broad understanding of the floristic diversity and vascular plant richness in the Gulf of Gabès. The obtained results reflected a disturbance–diversity pattern and thus revealed the obvious importance of maintaining the intermediate disturbance for biodiversity conservation and monitoring., SCOPUS: ar.j, info:eu-repo/semantics/published

Sediment-routing systems continuously transfer information and mass from eroding source areas to depositional sinks. Understanding how these systems alter environmental signals is critical when it comes to inferring source-area properties from the sedimentary record. We measure cosmogenic 10Be and 26Al along three large sediment-routing systems ( ∼ 100 000 km2) in central Australia with the aim of tracking downstream variations in 10Be-26Al inventories and identifying the factors responsible for these variations. By comparing 56 new cosmogenic 10Be and 26Al measurements in stream sediments with matching data (n = 55) from source areas, we show that 10Be-26Al inventories in hillslope bedrock and soils set the benchmark for relative downstream modifications. Lithology is the primary determinant of erosion-rate variations in source areas and despite sediment mixing over hundreds of kilometres downstream, a distinct lithological signal is retained. Post-orogenic ranges yield catchment erosion rates of ∼ 6-11 m Myr−1 and silcrete-dominant areas erode as slow as ∼ 0.2 m Myr−1. 10Be-26Al inventories in stream sediments indicate that cumulative-burial terms increase downstream to mostly ∼ 400-800 kyr and up to ∼ 1.1 Myr. The magnitude of the burial signal correlates with increasing sediment cover downstream and reflects assimilation from storages with long exposure histories, such as alluvial fans, desert pavements, alluvial plains, and aeolian dunes. We propose that the tendency for large alluvial rivers to mask their 10Be-26Al source-area signal differs according to geomorphic setting. Signal preservation is favoured by (i) high sediment supply rates, (ii) high mean runoff, and (iii) a thick sedimentary basin pile. Conversely, signal masking prevails in landscapes of (i) low sediment supply and (ii) juxtaposition of sediment storages with notably different exposure histories.

The need to find new sources of water due to the climatic conditions of certain areas of Spain, as well as the increasing urban tourism and agricultural demands, and in addition to the foreseen scenarios as a result of climate change, have led to the use of non-conventional resources, such as desalination. Although the Canary Islands already resorted to desalination plants 40 years ago, it was not until the 1990s that some of these plants began to be introduced to areas of high water deficit within the peninsula of Spain. Nevertheless, their boom occurred in 2005 due to the government’s propulsion of the ‘A.G.U.A.’ program, through which they installed a multitude of plants along the Mediterranean coast, as a result of a change in government and in its water management policy. This source was seen as an almost inexhaustible and suitable alternative in comparison with transfers, because of their regional and political controversies. The water generation capacity of these new plants was calculated based on demand perspectives related to the real estate boom, with demand in volumes that were never reached, due to the bursting of the real estate bubble and the economic crisis. In addition, the high-energy consumption associated with the desalination process (reverse osmosis) substantially increases the price of water, which makes it impossible for some sectors, especially irrigators, to have access to these waters. This communication details all the aspects related to the evolution of desalination in Spain, as well as its current situation, where as a consequence of the above, these plants, which entailed a significant economic investment, are working at very low yields and using their water as a strategic resource, especially during times of drought.

Preterm birth (born before 37 completed weeks of gestation) is one of the leading causes of death among children under 5 years of age. Several recent studies have examined the association between extreme temperature and preterm births, but there have been almost no such studies in arid Australia. In this paper, we explore the potential association between exposures to extreme temperatures during the last 3 weeks of pregnancy in a Central Australian town. An immediate effect of temperature exposure is observed with an increased relative risk of 1%–2% when the maximum temperature exceeded the 90th percentile of the summer season maximum temperature data. Delayed effects are also observed closer to 3 weeks before delivery when the relative risks tend to increase exponentially. Immediate risks to preterm birth are also observed for cold temperature exposures (0 to –6 ◦C), with an increased relative risk of up to 10%. In the future, Central Australia will face more hot days and less cold days due to climate change and hence the risks posed by extreme heat is of particular relevance to the community and health practitioners.

The need to find new sources of water due to the climatic conditions of certain areas of Spain, as well as the increasing urban tourism and agricultural demands, and in addition to the foreseen scenarios as a result of climate change, have led to the use of non-conventional resources, such as desalination. Although the Canary Islands already resorted to desalination plants 40 years ago, it was not until the 1990s that some of these plants began to be introduced to areas of high water deficit within the peninsula of Spain. Nevertheless, their boom occurred in 2005 due to the government’s propulsion of the ‘A.G.U.A.’ program, through which they installed a multitude of plants along the Mediterranean coast, as a result of a change in government and in its water management policy. This source was seen as an almost inexhaustible and suitable alternative in comparison with transfers, because of their regional and political controversies. The water generation capacity of these new plants was calculated based on demand perspectives related to the real estate boom, with demand in volumes that were never reached, due to the bursting of the real estate bubble and the economic crisis. In addition, the high-energy consumption associated with the desalination process (reverse osmosis) substantially increases the price of water, which makes it impossible for some sectors, especially irrigators, to have access to these waters. This communication details all the aspects related to the evolution of desalination in Spain, as well as its current situation, where as a consequence of the above, these plants, which entailed a significant economic investment, are working at very low yields and using their water as a strategic resource, especially during times of drought.

The natural flow regime of rivers has been strongly altered world-wide, resulting in ecosystem degradation and lakes drying up, especially in arid and semi-arid regions. Determining whether this is due mainly to climate change or to water withdrawal for direct human use (e.g. irrigation) is difficult, particularly for saline lake basins where hydrology data are scarce. In this study, we developed an approach for assessing climate and land use change impacts based on river flow records for headwater and lowland reaches of rivers, using the case of Lake Urmia basin, in north-westen Iran. Flow regimes at upstream and downstream stations were studied before and after major dam construction and irrigation projects. Data from 57 stations were used to establish five different time intervals representing 10 different land use development periods (scenarios) for upstream (not impacted) and downstream (impacted) systems. An existing river impact (RI) index was used to assess changes in three main characteristics of flow (magnitude, timing and, intra-annual variability). The results showed that irrigation was by far the main driving force for river flow regime changes in the lake basin. All stations close to the lake and on adjacent plains showed significantly higher impacts of land use change than headwaters. As headwaters are relatively unaffected by agriculture, the non-significant changes observed in headwater flow regimes indicate a minor effect of climate change on river flows in the region. The benefit of the method developed is clear interpretation of results based on river flow records, which is useful in communicating land use and climate change information to decision makers and lake restoration planners.

Groundwater is the principal water resource in semi-arid and arid environments. Therefore, quantitative estimates of its replenishment rate are important for managing groundwater systems. In dry regions, karst outcrops often show enhanced recharge rates compared with other surface and sub-surface conditions. Areas with exposed karst features like sinkholes or open shafts allow point recharge, even from single rainfall events. Using the example of the As Sulb plateau in Saudi Arabia, this study introduces a cost-effective and robust method for recharge monitoring and modelling in karst outcrops. The measurement of discharge of a representative small catchment (4.0 · 104 m2) into a sinkhole, and hence the direct recharge into the aquifer, was carried out with a time-lapse camera. During the monitoring period of two rainy seasons (autumn 2012 to spring 2014), four recharge events were recorded. Afterwards, recharge data as well as proxy data about the drying of the sediment cover are used to set up a conceptual water balance model. The model was run for 17 years (1971 to 1986 and 2012 to 2014). Simulation results show highly variable seasonal recharge–precipitation ratios between 0 and 0.27. In addition to the amount of seasonal precipitation, this ratio is influenced by the interannual distribution of rainfall events. Overall, an average annual groundwater recharge for the doline (sinkhole) catchment on As Sulb plateau of 5.1 mm has estimated for the simulation period.

Related to the characterization of plant parasitic nematodes halófita Salicornia bigelovii (Torr.) In northwestern Mexico, studies are zero, which motivated this research to the isolation and characterization of nematodes associated with Salicornia. Two systematically sampled in ten locations in two areas (Puerto Peñasco and Bahía de Kino, Sonora), which develops naturally in the halophyte study was developed; samplings were made at intervals of two months for 11 months corresponding to the phenology of the plant. Sampling depth levels of 0-50 and 50-100 cm was considered to study the nematode population. The collected samples were processed to homogenize the sample and taking subsamples of 500 g; subsamples were processed by sieving and centrifugation; aliquots for fication and identification were collected. Were collected and identified eight genera of plant parasitic nematodes; including the most abundant were Tylenchus, Helicotylenchus, Merlinius and Criconematidos. Their populations varied in relation to the ecotype, soil type, soil depth and season., Estudios relacionados con la caracterización de nemátodos fitoparásitos de la halófita Salicornia bigelovii (Torr.) en el noroeste de México, son nulos, lo que motivó esta investigación al aislamiento y caracterización de nemátodos asociados a Salicornia. Se desarrollaron dos muestreos sistemáticos en diez localidades de dos áreas (Puerto Peñasco y Bahía de Kino, Sonora), donde se desarrolla en forma natural la halófita en estudio; los muestreos se hicieron con una periodicidad de dos meses durante 11 meses que corresponde a la fenología de la planta. Se consideró una profundidad de muestreo en niveles de 0-50 y 50-100 cm para estudiar la población de nemátodos. Las muestras colectadas se procesaron al homogenizar la muestra y tomándose submuestras de 500 g; las submuestras fueron procesadas mediante un tamizado y centrifugación; se colectaron alícuotas para su cuantificación e identificación. Se colectaron e identificaron ocho géneros de nemátodos fitoparásitos; entre ellos los más abundantes fueron Tylenchus, Helicotylenchus, Merlinius y Criconematidos. Sus poblaciones variaron en relación con el ecotipo, tipo de terreno, profundidad del suelo y época del año.

Large-scale agroforestry in coastal arid and semi-arid regions could provide a geoengineering solution to anthropogenic climate change. Since agroforestry may impact on mesoscale climate in unknown ways, urgent research into potential impacts of large-plantations is needed to fully assess the viability and optimal placement for such schemes. Validated mesoscale simulations provide insights into feedbacks between land surface and atmosphere, particularly with respect to convective processes. Simulations of irrigated Simmondsia chinensis (jojoba) plantations were carried out with the WRF-NOAH atmosphere-land surface model using prescribed land surface and plant parameters. A sub-surface irrigation algorithm was developed based on critical soil moisture stress levels and implemented into the model code. The simulation of desert and plantation land surfaces was validated with field data from two sites in the Negev Desert - an arid desert site and a 400 ha jojoba plantation. For desert and vegetated surfaces, the model output of diurnal meteorological quantities and energy fluxes generally match well with the respective observations. Diurnal 2m-temperatures over the desert and plantation are matched by the model to within ± 0.2 °C and ± 1.5 °C, respectively. Wind speeds for both surfaces match to within 0.5 ms−1 and plantation latent heat is reproduced to within ± 20 Wm−2. Subsequent to validation, larger plantations of 100 km × 100 km were then simulated in two coastal arid regions, Israel and Oman over a period of one month and compared with control runs, without plantations. In Oman, convection and precipitation were triggered or enhanced by the plantation over multiple days whereas in Israel almost no impacts were observed. Two mechanisms were responsible for observed convection initiation: turbulent vertical transport of scalars due to increased surface heating and roughness as well as a low pressure-induced convergence at the canopy leeside. The, Großräumige Agrarforstwirtschaft in küstennahen ariden und semiariden Gebieten stellt eine Möglichkeit dar, mittels Geoengineering anthropogenem Klimawandel zu begegnen.Agrarforstwirtschaft wird das mesoskalige Klima jedoch in bisher unbekannter Weise beeinflussen. Daher ist es dringend notwendig, die möglichen Auswirkungen von großräumigen Plantagen in Bezug auf Durchführbarkeit und optimale Ausführung zu erforschen. Dazu geben validierte, mesoskalige Modellsimulationen Einblicke in die Wechselwirkungen zwischen Landoberfläche und Atmosphäre, insbesondere in Bezug auf konvektive Prozesse. Bewässerte Jojobaplantagen wurden mit dem Atmosphären-Landoberflächenmodell WRFNOAH simuliert. Dazu wurden die Landoberfläche und geeignete Pflanzenparameter fest vorgegeben. Ein neuer Algorithmus für die unterirdische Bewässerung wurde entwickelt und in den Modellcode implementiert. Die Simulation von Wüsten und Plantagenflächen wurde dann mittels Vergleich der Ergebnisse mit Feldmessungen von zwei Stationen in der Wüste Negev getestet. Eine Station befand sich an einem Wüsten-Standort und eine in einer 400 ha großen Jojobaplantage. Über den simulierten Wüsten und bewachsenen Flächen stimmen die Modellergebnisse der meteorologischen Größen und der Energieflüsse im Tagesverlauf im Allgemeinen gut mit den entsprechenden Beobachtungen überein. Der Tagesverlauf der 2m-Temperaturen in der Wüste und der Plantage bewegt sich im Bereich von ± 0,2 °C beziehungsweise ± 1,5 °C verglichen mit der Beobachtung. Die Windgeschwindigkeiten bewegen sich im Bereich von ± 0,5 ms−1 um die beobachteten Werte und der latente Wärmefluss zeigt Abweichungen von ± 20 Wm−2. Im Anschluss an die Validierung wurden größere Plantagen von je 100 km × 100 km in zwei repräsentativen ariden Küstengebieten (Israel und Oman) über einen Zeitraum von einem Monat simuliert und mit einem Kontrollexperiment ohne Plantagen verglichen. Im Oman löste die Plantage über mehrere Tage Feuchtekonvektion und Ni

Large-scale agroforestry in coastal arid and semi-arid regions could provide a geoengineering solution to anthropogenic climate change. Since agroforestry may impact on mesoscale climate in unknown ways, urgent research into potential impacts of large-plantations is needed to fully assess the viability and optimal placement for such schemes. Validated mesoscale simulations provide insights into feedbacks between land surface and atmosphere, particularly with respect to convective processes. Simulations of irrigated Simmondsia chinensis (jojoba) plantations were carried out with the WRF-NOAH atmosphere-land surface model using prescribed land surface and plant parameters. A sub-surface irrigation algorithm was developed based on critical soil moisture stress levels and implemented into the model code. The simulation of desert and plantation land surfaces was validated with field data from two sites in the Negev Desert - an arid desert site and a 400 ha jojoba plantation. For desert and vegetated surfaces, the model output of diurnal meteorological quantities and energy fluxes generally match well with the respective observations. Diurnal 2m-temperatures over the desert and plantation are matched by the model to within ± 0.2 °C and ± 1.5 °C, respectively. Wind speeds for both surfaces match to within 0.5 ms−1 and plantation latent heat is reproduced to within ± 20 Wm−2. Subsequent to validation, larger plantations of 100 km × 100 km were then simulated in two coastal arid regions, Israel and Oman over a period of one month and compared with control runs, without plantations. In Oman, convection and precipitation were triggered or enhanced by the plantation over multiple days whereas in Israel almost no impacts were observed. Two mechanisms were responsible for observed convection initiation: turbulent vertical transport of scalars due to increased surface heating and roughness as well as a low pressure-induced convergence at the canopy leeside. The, Großräumige Agrarforstwirtschaft in küstennahen ariden und semiariden Gebieten stellt eine Möglichkeit dar, mittels Geoengineering anthropogenem Klimawandel zu begegnen.Agrarforstwirtschaft wird das mesoskalige Klima jedoch in bisher unbekannter Weise beeinflussen. Daher ist es dringend notwendig, die möglichen Auswirkungen von großräumigen Plantagen in Bezug auf Durchführbarkeit und optimale Ausführung zu erforschen. Dazu geben validierte, mesoskalige Modellsimulationen Einblicke in die Wechselwirkungen zwischen Landoberfläche und Atmosphäre, insbesondere in Bezug auf konvektive Prozesse. Bewässerte Jojobaplantagen wurden mit dem Atmosphären-Landoberflächenmodell WRFNOAH simuliert. Dazu wurden die Landoberfläche und geeignete Pflanzenparameter fest vorgegeben. Ein neuer Algorithmus für die unterirdische Bewässerung wurde entwickelt und in den Modellcode implementiert. Die Simulation von Wüsten und Plantagenflächen wurde dann mittels Vergleich der Ergebnisse mit Feldmessungen von zwei Stationen in der Wüste Negev getestet. Eine Station befand sich an einem Wüsten-Standort und eine in einer 400 ha großen Jojobaplantage. Über den simulierten Wüsten und bewachsenen Flächen stimmen die Modellergebnisse der meteorologischen Größen und der Energieflüsse im Tagesverlauf im Allgemeinen gut mit den entsprechenden Beobachtungen überein. Der Tagesverlauf der 2m-Temperaturen in der Wüste und der Plantage bewegt sich im Bereich von ± 0,2 °C beziehungsweise ± 1,5 °C verglichen mit der Beobachtung. Die Windgeschwindigkeiten bewegen sich im Bereich von ± 0,5 ms−1 um die beobachteten Werte und der latente Wärmefluss zeigt Abweichungen von ± 20 Wm−2. Im Anschluss an die Validierung wurden größere Plantagen von je 100 km × 100 km in zwei repräsentativen ariden Küstengebieten (Israel und Oman) über einen Zeitraum von einem Monat simuliert und mit einem Kontrollexperiment ohne Plantagen verglichen. Im Oman löste die Plantage über mehrere Tage Feuchtekonvektion und Ni

Related to the characterization of plant parasitic nematodes halófita Salicornia bigelovii (Torr.) In northwestern Mexico, studies are zero, which motivated this research to the isolation and characterization of nematodes associated with Salicornia. Two systematically sampled in ten locations in two areas (Puerto Peñasco and Bahía de Kino, Sonora), which develops naturally in the halophyte study was developed; samplings were made at intervals of two months for 11 months corresponding to the phenology of the plant. Sampling depth levels of 0-50 and 50-100 cm was considered to study the nematode population. The collected samples were processed to homogenize the sample and taking subsamples of 500 g; subsamples were processed by sieving and centrifugation; aliquots for fication and identification were collected. Were collected and identified eight genera of plant parasitic nematodes; including the most abundant were Tylenchus, Helicotylenchus, Merlinius and Criconematidos. Their populations varied in relation to the ecotype, soil type, soil depth and season., Estudios relacionados con la caracterización de nemátodos fitoparásitos de la halófita Salicornia bigelovii (Torr.) en el noroeste de México, son nulos, lo que motivó esta investigación al aislamiento y caracterización de nemátodos asociados a Salicornia. Se desarrollaron dos muestreos sistemáticos en diez localidades de dos áreas (Puerto Peñasco y Bahía de Kino, Sonora), donde se desarrolla en forma natural la halófita en estudio; los muestreos se hicieron con una periodicidad de dos meses durante 11 meses que corresponde a la fenología de la planta. Se consideró una profundidad de muestreo en niveles de 0-50 y 50-100 cm para estudiar la población de nemátodos. Las muestras colectadas se procesaron al homogenizar la muestra y tomándose submuestras de 500 g; las submuestras fueron procesadas mediante un tamizado y centrifugación; se colectaron alícuotas para su cuantificación e identificación. Se colectaron e identificaron ocho géneros de nemátodos fitoparásitos; entre ellos los más abundantes fueron Tylenchus, Helicotylenchus, Merlinius y Criconematidos. Sus poblaciones variaron en relación con el ecotipo, tipo de terreno, profundidad del suelo y época del año.

According to predictions, extreme events such as droughts and heatwaves will increase in frequency and intensity in the near future. Droughts and heatwaves can have negative effect on forests leading to dieback of more sensitive tree species with negative effect on ecosystem stability. The response of trees to stress conditions can vary between species or within one species, and such variation may depend on specific adaptations of trees to their preferred habitat. This study focuses on Australian trees from two common genera – Acacia and Eucalyptus, which have many species distributed across different habitats. Adaptation to various habitats of congeneric species provides a good model for studying responses of defence system to drought and heatwave stresses of ecologically different, but closely related species. Responses of the defence systems under stress conditions can help to understand which species will cope more efficiently under future climate change predictions. This thesis consists of one meta-analytical review on antioxidative and photoprotective defence system responses to drought stress, three experimental studies conducted under controlled conditions and one field study. In the controlled experiments, two Acacia and two Eucalyptus species adapted to contrasting habitats were exposed to drought stress or heatwaves conditions and to a combination of both stress factors. Response of seedlings to the treatments was examined with measurements of antioxidative defence systems, specifically two ubiquitous and abundant low-molecular weight antioxidants glutathione and ascorbic acid, along with gas-exchange, chlorophyll fluorescence and gene-expressions measurements. In the field study, responses of antioxidative defence systems were measured on multiple provenances within one species in a common garden experiment. Provenances were from different sites of origin representing a range of habitats with different annual rainfall. It was hypothesised that responses

Large-scale agroforestry in coastal arid and semi-arid regions could provide a geoengineering solution to anthropogenic climate change. Since agroforestry may impact on mesoscale climate in unknown ways, urgent research into potential impacts of large-plantations is needed to fully assess the viability and optimal placement for such schemes. Validated mesoscale simulations provide insights into feedbacks between land surface and atmosphere, particularly with respect to convective processes. Simulations of irrigated Simmondsia chinensis (jojoba) plantations were carried out with the WRF-NOAH atmosphere-land surface model using prescribed land surface and plant parameters. A sub-surface irrigation algorithm was developed based on critical soil moisture stress levels and implemented into the model code. The simulation of desert and plantation land surfaces was validated with field data from two sites in the Negev Desert - an arid desert site and a 400 ha jojoba plantation. For desert and vegetated surfaces, the model output of diurnal meteorological quantities and energy fluxes generally match well with the respective observations. Diurnal 2m-temperatures over the desert and plantation are matched by the model to within ± 0.2 °C and ± 1.5 °C, respectively. Wind speeds for both surfaces match to within 0.5 ms−1 and plantation latent heat is reproduced to within ± 20 Wm−2. Subsequent to validation, larger plantations of 100 km × 100 km were then simulated in two coastal arid regions, Israel and Oman over a period of one month and compared with control runs, without plantations. In Oman, convection and precipitation were triggered or enhanced by the plantation over multiple days whereas in Israel almost no impacts were observed. Two mechanisms were responsible for observed convection initiation: turbulent vertical transport of scalars due to increased surface heating and roughness as well as a low pressure-induced convergence at the canopy leeside. The, Großräumige Agrarforstwirtschaft in küstennahen ariden und semiariden Gebieten stellt eine Möglichkeit dar, mittels Geoengineering anthropogenem Klimawandel zu begegnen.Agrarforstwirtschaft wird das mesoskalige Klima jedoch in bisher unbekannter Weise beeinflussen. Daher ist es dringend notwendig, die möglichen Auswirkungen von großräumigen Plantagen in Bezug auf Durchführbarkeit und optimale Ausführung zu erforschen. Dazu geben validierte, mesoskalige Modellsimulationen Einblicke in die Wechselwirkungen zwischen Landoberfläche und Atmosphäre, insbesondere in Bezug auf konvektive Prozesse. Bewässerte Jojobaplantagen wurden mit dem Atmosphären-Landoberflächenmodell WRFNOAH simuliert. Dazu wurden die Landoberfläche und geeignete Pflanzenparameter fest vorgegeben. Ein neuer Algorithmus für die unterirdische Bewässerung wurde entwickelt und in den Modellcode implementiert. Die Simulation von Wüsten und Plantagenflächen wurde dann mittels Vergleich der Ergebnisse mit Feldmessungen von zwei Stationen in der Wüste Negev getestet. Eine Station befand sich an einem Wüsten-Standort und eine in einer 400 ha großen Jojobaplantage. Über den simulierten Wüsten und bewachsenen Flächen stimmen die Modellergebnisse der meteorologischen Größen und der Energieflüsse im Tagesverlauf im Allgemeinen gut mit den entsprechenden Beobachtungen überein. Der Tagesverlauf der 2m-Temperaturen in der Wüste und der Plantage bewegt sich im Bereich von ± 0,2 °C beziehungsweise ± 1,5 °C verglichen mit der Beobachtung. Die Windgeschwindigkeiten bewegen sich im Bereich von ± 0,5 ms−1 um die beobachteten Werte und der latente Wärmefluss zeigt Abweichungen von ± 20 Wm−2. Im Anschluss an die Validierung wurden größere Plantagen von je 100 km × 100 km in zwei repräsentativen ariden Küstengebieten (Israel und Oman) über einen Zeitraum von einem Monat simuliert und mit einem Kontrollexperiment ohne Plantagen verglichen. Im Oman löste die Plantage über mehrere Tage Feuchtekonvektion und Ni

The challenges of sampling rare fauna limit efforts to understand and mitigate the factors that restrict their distribution. Camera traps have become a standard technique for sampling large mammals, but their utility for sampling small, rare species remains largely unknown. The central rock-rat (Zyzomys pedunculatus) is critically endangered and restricted to rugged range country in central Australia. Using Z. pedunculatus as a focal species, we sought to evaluate the effectiveness of camera trapping for sampling small mammals in this environment and to better understand the factors driving the occurrence of this species. We installed baited camera traps at 50 sites across 1795 ha of core refuge habitat for Z. pedunculatus. We recorded all six species of small mammals known previously from this area, including the highly detectable Z. pedunculatus at five sites. Occupancy modelling showed that distance to the nearest occupied site was the most important predictor of Z. pedunculatus occurrence, suggesting that this rodent occurs in discrete sub-populations within the matrix of refuge habitat. Fire history and ruggedness may also influence occupancy of Z. pedunculatus at the landscape-scale and could assist in locating additional sub-populations. At the site-scale, occupancy of Z. pedunculatus was high and there was no clear influence of any site-scale variables. Management of Z. pedunculatus will require protection and expansion of known sub-populations. We conclude that camera trapping provided useful and cost-effective insight into the factors limiting rock-rat distribution, and predict that it will become a standard tool for sampling rare small mammals in difficult-to-access environments.

Biological invasions often occur through expansion of satellite populations that become established at 'invasion hubs'. Invasion hubs can result from random dispersal events, but frequently arise when invading individuals actively choose habitats using cues that signify high-quality environments where the fitness consequences are positive. Theoretical studies suggest that targeted control at invasion hubs can effectively suppress the populations and impacts of invaders. In arid Australia, small dams that provide water for livestock function as invasion hubs by providing an invasive vertebrate, the cane toad Rhinella marina, with refuge from extreme aridity during the annual dry season. Toads are attracted to dams and use them as stepping stone habitats from which they disperse during rainy periods. Here, we ask whether sustained control of this invasive vertebrate can be achieved by converting invasion hubs into ecological traps. We did this by manipulating invasion hub habitats to induce a mismatch between toads' habitat preference and the fitness consequences of their habitat choice to cause high mortality. We constructed fences to exclude toads from dams and maintained these fences for 1 year. This period encompassed periods of dry and wet seasonal climatic conditions. Our manipulation did not alter the attractive cues for invading toads which died en masse while attempting to settle at fenced dams that prevented toads from reaching water. Toad populations at the fenced dams were suppressed by 1-2 orders of magnitude compared to unfenced controls and procedural controls. Toad populations remained suppressed for a year after exclusion. By excluding toads from dams, we converted invasion hubs into ecological traps and effectively thwarted the reinvasion of cane toads. Our research suggests that water exclusion devices could be used to prevent toad invasion or to control cane toad populations in arid landscapes colonized by toads. Synthesis and applications. Our stu

Although large areas of semi-arid land are extensively cropped, few studies have investigated the effect of nitrogen (N) fertiliser on nitrous oxide (N2O) emissions in these regions (Galbally et al. 2010). These emissions need to be measured in order to estimate N losses and calculate national greenhouse gas inventories. We examined the effect of different agronomic management practices applied to wheat (Triticum aestivum) grown on an alkaline Vertosol in south-eastern Australia on N2O emissions. In 2007, N2O emissions were measured over 12 months, during which N fertiliser (urea) was applied at sowing or N fertiliser plus supplementary irrigation (50 mm) was applied during the vegetative stage and compared with a treatment of no N fertiliser or irrigation. In a second experiment (2008), the effect of source of N on N2O emissions was examined. Wheat was grown on plots where either a pulse (field peas, Pisum sativum) or pasture legume (barrel medic, Medicago truncatula) crop had been sown in the previous season compared with a non-legume crop (canola, Brassica napus). To account for the N supplied by the legume phase, N fertiliser (50 kg N ha-1 as urea) was applied only to the wheat in the plots previously sown to canola. Fluxes of N2O were measured on a sub-daily basis (up to 16 measurements per chamber) by using automated chamber enclosures and a tuneable diode laser, and treatment differences were evaluated by a linear mixed model including cubic smoothing splines. Fluxes were low and highly variable, ranging from -3 to 28 ng N2O-N m-2 s-1. The application of N fertiliser at sowing increased N2O emissions for ~2 months after the fertiliser was applied. Applying irrigation (50 mm) during the vegetative growth stage produced a temporary (~1-week) but non-significant increase in N2O emissions compared with plots that received N fertiliser at sowing but were not irrigated. Including a legume in the rotation significantly increased soil inorganic N at sowing of the fol

The challenges of sampling rare fauna limit efforts to understand and mitigate the factors that restrict their distribution. Camera traps have become a standard technique for sampling large mammals, but their utility for sampling small, rare species remains largely unknown. The central rock-rat (Zyzomys pedunculatus) is critically endangered and restricted to rugged range country in central Australia. Using Z. pedunculatus as a focal species, we sought to evaluate the effectiveness of camera trapping for sampling small mammals in this environment and to better understand the factors driving the occurrence of this species. We installed baited camera traps at 50 sites across 1795 ha of core refuge habitat for Z. pedunculatus. We recorded all six species of small mammals known previously from this area, including the highly detectable Z. pedunculatus at five sites. Occupancy modelling showed that distance to the nearest occupied site was the most important predictor of Z. pedunculatus occurrence, suggesting that this rodent occurs in discrete sub-populations within the matrix of refuge habitat. Fire history and ruggedness may also influence occupancy of Z. pedunculatus at the landscape-scale and could assist in locating additional sub-populations. At the site-scale, occupancy of Z. pedunculatus was high and there was no clear influence of any site-scale variables. Management of Z. pedunculatus will require protection and expansion of known sub-populations. We conclude that camera trapping provided useful and cost-effective insight into the factors limiting rock-rat distribution, and predict that it will become a standard tool for sampling rare small mammals in difficult-to-access environments.