Journal of Arid Environments最新文献

Cacti usually grow in areas with severe resource limitations, making them vulnerable to local extinction. To ensure their survival, cacti have evolved a differential allocation of resources that is reflected in trade-offs among vital rates. In this study, we assess the effect of interannual climatic variation on resource allocation to vital rates in a cactus with biogeographical rarity (Thelocactus leucacanthus ssp. schmollii). Eight-year observations were used to relate vital rates to climatic data using population projection matrix models and Spearman correlations. The finite rate of population growth (λ) indicates, on average, a population in equilibrium. The transition from seeds to seedlings and the growth of seedlings, juveniles, and adults are the stages of the lifecycle with the highest selection pressure, with adults and juveniles being the categories with the greatest contribution to λ. This species allocates more resources to survival than to growth or reproduction during its lifecycle. The trade-off between the survival of adult individuals and fertility seems more marked in years with higher rainfall and minimum temperature turned out to be a key factor for population maintenance. This research provides new insights into the strategies used by rare globose cacti to avoid extinction in these limiting environments.

We investigated for the first time, the seasonal patterns of iono- and osmotic responses of the Souss Valley tortoises, Testudo graeca graeca, in an arid steppe-land of west-central Morocco, a year-round (2011–2012). The mean body mass condition index varied significantly over time, with significantly higher values in males in summer and autumn 2011. All the plasma variables (osmolality and sodium, potassium, chloride, and urea concentrations) varied significantly among seasons, increasing during the summer dry period and decreasing after rainstorms. Osmolality and solute concentrations in voided urine were more variable than in plasma, with more pronounced decreases related to rainfall events. Soluble potassium was the major cation in voided urine. Potassium concentration decreased markedly following rainfall events, and rapidly increased in late summer and autumn 2011, when some green plants were available. As spring progressed and tortoises gained body mass while feeding on hydrated vegetation, urine osmolalities decreased, and then re-increased during the dry summer period, becoming essentially iso-osmotic with plasma. When summer thundershowers dropped rain, tortoises drank water, voided concentrated bladder urine, and stored dilute urine; body mass, plasma and urine concentrations returned to hydrated levels. Tortoises exhibited a tolerance to osmotic stressors that allowed them to osmoregulate opportunistically in their arid environments via allostasis, a process that allows maintaining homeostasis through change. When bladder urine becomes iso-osmotic to plasma, tortoises tolerate increases in osmolality and concentrations of plasma solutes. The success of facultative osmoregulation and variable ‘allostasis’ would depend on the occurrence of summer rain events as a source of drinking in osmotically stressed tortoises.

The Blanford's fox (Vulpes cana) is a small canid species classified as Least Concern by the IUCN Red List. They predominantly inhabit mountainous regions in arid ecosystems across the Arabian Peninsula, Central Asia and North Africa. In the Kingdom of Saudi Arabia (KSA), the species has been recorded only in limited localities and its population is believed to be in decline. We present data from camera trapping surveys conducted between March 2020 and December 2022 to update and confirm the species' known distribution in KSA. We captured 470 independent captures of Blanford's fox at 21 survey sites, representing 191 spatially independent locations. We used ensemble species distribution modelling to predict areas of suitable habitat within their IUCN Red List distribution range. Our results suggest that the most favourable habitats for theBlanford's fox in KSA are in the rugged, mountainous areas along the southwestern Asir range. These findings provide insights into the species' distribution and may support future conservation efforts to maintain viable populations of Blanford's fox in KSA.

The Levant is a climatically sensitive region that suffers from prolonged heat waves contributing to societal crisis and massive population displacements. At least since 2010 and the so-called Arab Spring, the region has experienced recurring socio-political turmoil and the Syrian civil war, which amplified economic and ecological pressure on the neighbouring countries. Particularly in Jordan, the strong population growth in addition to the immigration of hundreds of thousands Syrian refugees has led to massive changes in land-use and built-up infrastructure, resulting in an over-exploitation of the landscape through irrigated crop plantations and unregulated construction activities. Currently, the situation is further socio-politically fuelled by the so-called Palestinian-Israeli Conflict. The interplay of climate variability, built-up change, landcover transformation, and population development, however, is not yet fully understood. In this article, a multicomponent trend analysis from climate variables, satellite imagery, and landcover datasets is presented that highlights the strong increase in building activity over the past decades and emphasizes the interconnection of climate change prediction models and current socio-political development in the Levant. Groundwater exploitation for domestic use, crop production, and industrial purposes will further enhance social inequality, the pressure on the local ecological functionalities, and risks severe and irreversible land degradation.

The study was conducted in the Dry Chaco of central Argentina, assessing the seed dispersal role of Black-legged seriemas (Chunga burmeisteri). We collected 42 faeces of C. burmeisteri and found that all of them contained seeds from at least three woody plant species: algarrobo dulce (Neltuma flexuosa), tintitaco (Strombocarpa torquata) and mistol (Sarcomphalus mistol). We were able to compare the germination rates of seeds found in the faeces of C. burmeisteri with control seeds that did not undergo endozoochory only for N. flexuosa. The percentage of germinated seeds was slightly higher in the seeds that were ingested by C. burmeisteri compared to the control group. This study provides the first evidence of C. burmeisteri ‘s role as a seed disperser for dominant trees in the Dry Chaco forest. The discovery is surprising because C. burmeisteri was previously known only for its predatory behaviour. These findings highlight the need for further research on tree dispersal by vertebrates in the Chaco region, considering that dry forests, like the Chaco, are among the most threatened ecosystems worldwide.

Climate change is a major threat to ecosystems and global biodiversity, directly impacting spatial species distribution. Using a species distribution modeling approach to predict present and future spatial distributions, we estimated the effects of future global warming on the wild tropical forages Stylosanthes capitata and Stylosanthes macrocephala. We modeled these species distributions, considering four representative concentration pathway (RCP) scenarios spanning years 2080–2100. Our findings suggest both Stylosanthes species will undergo severe spatial displacement and a reduction of high-suitability areas across all temporal scenarios. Albeit some noticeable expansion into new areas, their suitability is notably low, especially under the RCP 6.0 and RCP 8.5 scenarios. Particularly, S. capitata exhibits a relatively higher resilience to climate changes projected in the RCP 2.6 scenario. However, these changes rate surpasses initial predictions, placing these species at an elevated risk of extinction in the near future. Our main highlight emphasizes the conservation urgency and management strategies to mitigate climate change impacts on these tropical forage species.

In (semi-)arid regions, harvesting fog and dew can become a complementary solution to traditional water supply. In the Atacama region, a territory of key and water-dependent economic activities, both fog and dew are driven by the advection of marine moisture from the Pacific. Still, little is described regarding the dynamics and water potential of these events. In this study, we analyze the spatiotemporal variability of fog and dew in the Atacama Desert to assess the potential of non-rainfall atmospheric water harvesting. Our research strategy combines three methods to achieve a comprehensive understanding of these phenomena: a satellite-spatial analysis of fog and low cloud frequencies; a thermodynamic characterization of the fog cloud vertical structure; and an observational analysis of fog and dew water collection. Our findings reveal that fog is a regular phenomenon in the area, occurring from 3% to 20% of the year. We estimate that fog cloud reaches 50 km inland and up to ∼1100 m ASL, covering a vast territory where it can be harvested. Fog and dew represent 72% and 28% of the total collected atmospheric water (∼0.2 L m⁻² day⁻¹). Both fog and dew represent a complementary natural water source with multiple uses for local industries.

Desert kites are communal game traps that were used to harvest herds of ungulates, and there are more than 6000 in the arid zones of southwestern Asia. The oldest were dated to the 9th millennium cal B.C. and some were reused until the beginning of the 20th century. A wide range of types and dimensions is found throughout the region, but only the small V-shaped type is found in the cultural landscape of the Timnian, a Mid-Holocene culture in the southern Levantine deserts. The Timnian economy was based on nomadic pastoralism, rearing small herds of goats/sheep. In the southern Levantine deserts, pastoralism had to be augmented by other carbohydrate sources. It is apparent that the Timnians invested much effort and resources in kite construction to hunt ungulates; however, faunal assemblages from habitation camps, burial fields and ceremonial complexes show very few bones of hunted game. Here we test two competing hypotheses: the use of kites to augment food supply, versus the use of kites for social or ceremonial purposes. We review the Timnian culture, the local kites, and cost-benefits considerations, as well as issues regarding desert pastoralism. We conclude that the kites were mostly used in social and ceremonial contexts.

The study aimed to determine the optimal ratio for the mixture of forage cactus and corn stover silage, emphasizing the evaluation of fermentative profile, microbial populations, dry matter losses, chemical composition, and aerobic stability. A completely randomized design with four treatments and five replications was employed in this study. Treatments included varying proportions of forage cactus in corn stover at ensiling (0%, 10%, 20%, and 40% of fresh matter). After a 100-day fermentation period, the assayed variables underwent regression analysis. Forage cactus inclusion led to linear dry matter and ether extract reductions, with crude protein showing a negative quadratic effect (p < 0.05). The pH and water-soluble carbohydrates exhibited negative quadratic effects with the increasing proportion of forage cactus (p < 0.05). Lactic and acetic acids exhibited quadratic effects, reaching their peaks at approximately 20% forage cactus (p < 0.05). Lactic acid bacteria demonstrated a linear decrease, while yeasts/molds displayed a negative quadratic effect (p < 0.05). Dry matter losses followed a quadratic pattern, with the minimum values observed at 20% forage cactus (p < 0.05). Additionally, the inclusion of forage cactus significantly enhanced aerobic stability (p < 0.05). The incorporation of 20% forage cactus into corn stover silage markedly improved its quality.

In this work, a new approach to using NDVI as a predictor of water quality parameters in arid environments is proposed. Our focus was the Araçuaí river basin, which has a predominance of native cerrado vegetation and is subject to seasonal variations in rainfall and vegetation cover. MODIS images (MOD13Q1) from 2000 to 2018 were used to calculate the NDVI of the contributing areas of the water quality monitoring stations and to analyze its relationship with fourteen water quality parameters. The NDVI showed significant seasonality, with high values in the rainy season, and temporal trends of increase in stretches related to the main river. A strong and new relationship was observed between NDVI and six water quality parameters: color, total dissolved solids, total suspended solids, total solids, nitrate and turbidity, this being stronger at the local scale, with better performance at from models that use incremental NDVI, capturing local variations in vegetation cover, instead of regional NDVI, which reflects the general state of vegetation. The results demonstrate the potential of using these indices to develop and improve prediction models of water quality parameters in river basins and to expand the spatial and temporal coverage of water quality monitoring.