Despite the significant global impact of oil spills on the environment, little is known about the effects of oil spills on animals in terrestrial ecosystems, particularly in desert environments. In contaminated areas, habitat selection can be a crucial behavior determining individuals survival as well as a potential indicator of an ecosystem’s condition. This is especially relevant for ground-dwelling insects, whose close interactions with the soil make them valuable bioindicators of soil quality.

This study aimed to determine the long and short-term effects of oil spills on the microhabitat selection behavior of ground-dwelling insects in a hyper-arid desert. Soil samples were collected from a nature reserve that experienced two oil spills, one in 1975 and another in 2014. We conducted microhabitat selection experiments in laboratory conditions using the ground-dwelling Mesostena angustata beetles and Myrmeleon hyalinus antlion larvae.

When given a choice between clean soil (control) and soil contaminated in 2014, both beetles and antlions selected the clean soil, with antlions exhibiting reduced movements and no pit-trap digging in contaminated soil. Surprisingly, both beetles and antlions selected the soil contaminated in 1975 over other soil types. However, the antlions kept relocating their pit-falls traps in the 1975 polluted soil, which may indicate they perceived this soil as less suitable for pit digging. When given a choice between three types of soil, the beetles clearly preferred dark, oil-contaminated soils and avoided the clean soil.

Our study highlights the complex and varied effects of oil spills on microhabitat selection behavior in ground-dwelling insects, indicating the importance of considering long-term effects in future restoration efforts.

Implications for insect conservation: This study shows that oil contamination impacts ground dwelling insects behavior even more than four decades after an oil spill. The attraction of both insect species to the contaminated soil from 1975 may be an indication of an ecological trap for these species in the field. We conclude in this study that the habitat selection behavior of the antlion larvae may be a good behavioral indicator for habitat restoration purposes.

The forecasted increased frequency and intensity of extreme climatic events may strongly affect ecosystem structure and function in the future. It is unclear how ecosystems will function in the long run over a large spatial scale under a new extreme water cycle. This open question calls for a conceptual framework as a fundamental basis for theoretical and experimental exploration of ecosystem function on a large scale driven by an extreme climate envelope. To assess the problem on a large scale, we investigated hyper-arid ecosystems (HAEs) as natural tangible models that already function under an extreme climatic envelope. Our new assertion is that if extreme climate change drives arid lands to function under alternate extreme conditions, then arid land ecosystems will function like an HAE as an alternative state, rather than progress to desertification. To support our assertion, we developed a conceptual framework of HAEs that includes a geo-hydrological “abiotic engine” that drives HAE function by soil moisture diversity and plant functional groups. Based on this conceptual framework, we suggest incorporating two new hypotheses in climate change studies to advance our understanding of responses of large-scale, water-limited ecosystems: (1) Hydro-climatic extremes in water-limited ecosystems will reduce the degree of resource conservation by slope ecosystems due to reduction in plant cover and soil. The decreased ecosystem function on the slope will be compensated for by increasing the effect of the abiotic engine on the ephemeral stream, thus enhancing meta-ecosystem functioning in the ephemeral stream. (2) In water-limited ecosystems, climate change toward hydro-climatic extremes will rescale the dominant hydro-ecological processes of pulse–reserve, source–sink, and connectivity along the semiarid, arid, and HA gradients in two ways: (i) shrinking of both spatial and temporal dimensions; and (ii) shrinking in the temporal dimension and expanding in the spatial dimensions. The first rescaling trajectory is related to biodiversity–ecosystem function and the second to the abiotic engine processes.

Evaporative cooling due to transpiration of urban trees in two contrasting climates is the subject of this study. Transpiration was studied experimentally on local tree species at ‘tree lab’ sites in Munich, Germany (temperate climate) and in Beer Sheva, Israel (hot arid climate), within various settings (park, street, square) with natural and sealed surface conditions. The comparison was based on linear relationship of midday canopy resistance to atmospheric vapor pressure deficit (VPD), where the slope is proportional to tree hydraulic conductance and midday stem water potential. Sap flux densities in all trees were similar but crown projected area (CPA) was larger in Beer Sheva, resulting in higher hydraulic resistance that limits transpirational cooling (regression slopes of 0.25–0.44 in Beer Sheva vs. 0.10–0.18 in Munich). The contribution of the transpirational cooling, studied as the proportion of latent heat to total available energy was about 40% less significant at noon hours in summer in Beer Sheva than in Munich. Results suggested that shading should be the main consideration in planting local trees in hot dry climates. The linear relationship of midday canopy resistance to VPD is proposed as an operative tool for comparing evaporative cooling between local trees in different climatic regions.

Litter decomposition is a key process for carbon and nutrient cycling in terrestrial ecosystems and is mainly controlled by environmental conditions, substrate quantity and quality as well as microbial community abundance and composition. In particular, the effects of climate and atmospheric nitrogen (N) deposition on litter decomposition and its temporal dynamics are of significant importance, since their effects might change over the course of the decomposition process. Within the TeaComposition initiative, we incubated Green and Rooibos teas at 524 sites across nine biomes. We assessed how macroclimate and atmospheric inorganic N deposition under current and predicted scenarios (RCP 2.6, RCP 8.5) might affect litter mass loss measured after 3 and 12 months. Our study shows that the early to mid-term mass loss at the global scale was affected predominantly by litter quality (explaining 73% and 62% of the total variance after 3 and 12 months, respectively) followed by climate and N deposition. The effects of climate were not litter-specific and became increasingly significant as decomposition progressed, with MAP explaining 2% and MAT 4% of the variation after 12 months of incubation. The effect of N deposition was litter-specific, and significant only for 12-month decomposition of Rooibos tea at the global scale. However, in the temperate biome where atmospheric N deposition rates are relatively high, the 12-month mass loss of Green and Rooibos teas decreased significantly with increasing N deposition, explaining 9.5% and 1.1% of the variance, respectively. The expected changes in macroclimate and N deposition at the global scale by the end of this century are estimated to increase the 12-month mass loss of easily decomposable litter by 1.1–3.5% and of the more stable substrates by 3.8–10.6%, relative to current mass loss. In contrast, expected changes in atmospheric N deposition will decrease the mid-term mass loss of high-quality litter by 1.4–2.2% and that of low-quality litter by 0.9–1.5% in the temperate biome. Our results suggest that projected increases in N deposition may have the capacity to dampen the climate-driven increases in litter decomposition depending on the biome and decomposition stage of substrate.

Substantial evidence now suggests that a positive diversity–stability relationship exists. Yet few studies examine the facets of biodiversity that contribute to this relationship, and empirical research is predominantly conducted on grassland communities under controlled conditions. We investigate the roles of species richness, environmental condition (vegetation cover), asynchrony, and weighted population stability in driving community stability across multiple taxa. We used data from a Long-term Ecological Research project to investigate temporal stability of annual plants, beetles, reptiles, and rodents in Nizzanim Coastal Sand Dune Nature Reserve in Israel. All four taxa had a strong positive relationship between asynchrony and community stability. Only rodents showed a positive richness–stability relationship. Perennial plant cover had a significant relationship with community stability for three taxa, but the direction of the correlation varied. Asynchrony had a stronger relationship with perennial plant cover than it did with richness for both plants and beetles. We suggest that community stability is driven by asynchrony for flora as well as fauna. Stability appears to be determined by species’ interactions and their responses to the environment, and not always by diversity. This has important consequences for understanding the effects of environmental degradation on ecosystem stability and productivity, which have destabilizing consequences beyond biodiversity loss.

The construction of vehicular roads likely affects the distribution of natural resources. Although the effects of roads on different ecosystem aspects have been extensively studied, studies in arid and, particularly, in hyper-arid ecosystems are scarce. In drylands, where water is the main limiting factor, the effect of roads on the redistribution of water may have strong subsequent effects on the ecosystem, especially when roads cross natural water flow paths. To fill this knowledge gap, we studied the effects of a road that runs across a slope on the distribution of plants and animals in a hyper-arid environment. Changes in shrub cover, below and above the road, were quantified by remote sensing and image classification, while plant-associated arthropods were vacuum-sampled from shrub canopies and from open (inter-shrub) areas. We found that the spatial distribution of shrubs, a vital resource facilitating many other organisms, was affected by the road, with an increase in the shrub cover immediately above the road and a decrease below it. Arthropod abundance generally followed shrub cover, but the exact pattern depended on the specific group sampled. While some arthropod groups (e.g., aphids, parasitic wasps and barklice) thrived under the disturbed conditions above the road, other arthropod groups (e.g., mites and true bugs) were less abundant in the disturbed patches. Our results highlight the strong effects of human-made structures on the distribution of flora and fauna in arid ecosystems.

Water availability, which enables plant growth and animal activity, regulates dryland ecosystem function. In hyper-arid ecosystems, rain cannot support vascular plant growth. Therefore, hyper-arid vegetation is restricted to the lower topography, where runoff accumulates. Typically, food resources originating from areas of dense vegetation are dispersed across the desert floor, enabling animal life in areas lacking vascular plant growth. However, certain regions, such as the hyper-arid upper topography, may be devoid of plant-derived food resources. The present study examined arthropod activity in the upper topography of a hyper-arid desert, in comparison with arthropod activity in the lower topography. Pitfall traps were utilized to compare arthropod activity along unvegetated ridges with activity in parallel, vegetated riverbeds. Surprisingly, the study revealed dense arthropod communities in the barren upper topography. Arthropods collected in the upper topography represented 26% of total arthropod abundance. In addition, the overlap between arthropod identity in the ridges and wadis (i.e., riverbeds) was low, and certain arthropods were strongly affiliated with the ridges. The upper topographic communities included high numbers of silverfish (Zygentoma: Lepismatidae), malachite beetles (Psiloderes), and predatory mites (Acari: Anystidae), and these arthropods were present at various life stages. It remains unclear how arthropod communities can persist in the unvegetated upper topography of the hyper-arid study area. These results raise the possibility that other food sources, independent from vascular plants, may play a significant role in the life history of hyper-arid arthropods.

In plant eco-physiology, less negative (enriched) carbon 13 (¹³C) in the leaves indicates conditions of reducing leaf gas exchange through stomata, e.g. under drought. In addition, ¹³C is expected to be less negative in non-photosynthetic tissues as compared with leaves. However, these relationships in δ ¹³C from leaves (photosynthetic organs) to branches, stems and roots (non-photosynthetic organs) are rarely tested across multiple closely related tree species, multiple compartments, or in trees growing under extreme heat and drought.

We measured leaf-to-root ¹³C in three closely related desert acacia species (Acacia tortilis, A. raddiana and A. pachyceras). We measured δ ¹³C in leaf tissues from mature trees in southern Israel. In parallel, a 7-year irrigation experiment with 0.5, 1.0 or 4.0 L day⁻¹ was conducted in an experimental orchard. At the end of the experiment, growth parameters and δ ¹³C were measured in leaves, branches, stems and roots.

The δ ¹³C in leaf tissues sampled from mature trees was ca. −27‰, far more depleted than expected from a desert tree growing in one of the Earth’s driest and hottest environments. Across acacia species and compartments, δ ¹³C was not enriched at all irrigation levels (−28‰ to ca. −27‰), confirming our measurements in the mature trees. Among compartments, leaf δ ¹³C was unexpectedly similar to branch and root δ ¹³C, and surprisingly, even less negative than stem δ ¹³C. The highly depleted leaf δ ¹³C suggests that these trees have high stomatal gas exchange, despite growing in extremely dry habitats. The lack of δ ¹³C enrichment in non-photosynthetic tissues might be related to the seasonal coupling of growth of leaves and heterotrophic tissues.

Background: The cessation of anthropogenic activities in mobile sand dune ecosystems under xeric arid conditions has resulted in the gradual stabilization of dunes over the course of five decades. Our objective was to analyze the spatial patterns of arthropod assemblages along a gradient of different stabilization levels, which represents the different stages of dune stabilization - from the shifting crest of the dune to the stabilized crusted interdune. The study was carried out at the sand dunes of the northwestern Negev in Israel. Data was collected using dry pitfall traps over two consecutive years during the spring along northern windward aspects. Four dunes were chosen, characterized by three significant landscape units: shifting crest, semi-stabilized slope and stabilized interdune. Results: We identified three significant assemblages of arthropods along the gradient. The shifting dune crests are populated by psammophilic species found almost exclusively in sandy habitats in Egypt and the western Negev in Israel. The crusted, stabilized inter-dunes are populated mainly by loess-dwelling species, which are common in most of the Negev loess plains and have a wide distribution range, and the semi-stabilized slopes host species of both extreme landscape units but is distinguished by four species that show significant affinity to it. Conclusions: Our results demonstrate functional arthropod heterogeneity and emphasize the risk of regional species homogenization. Heterogeneity is a key property in maintaining sand dune biodiversity. Homogenization, as a result of sand stabilization, may lead to loss of psammophilic species.

As ecosystems do not follow human-made borders, cross-border environmental cooperation can be highly effective, perhaps even necessary, for both scientific insight and conservation efforts. Several environmental cooperation initiatives between Israel and Jordan emerged since the peace treaty of 1994. These initiatives had the explicit double goal of peacebuilding and enhancing regional environmental protection. However, as political relations between Israel and Jordan have been unstable and often tense during this period, cooperation toward these goals has often proved challenging. The current study investigates one such attempt at regional scientific environmental cooperation, specifically, cooperation between Jordanian and Israeli long-term socioecological research centers. Eleven in-depth interviews with Israeli and Jordanian scientists, who constitute all the participating scientists in this initiative, were conducted in order to identify the benefits and challenges of their cross-border collaboration. A thematic analysis of the interview contents was then performed to compare the results with models and theories pertaining to intergroup relations from the field of social psychology, theories that are particularly relevant to this case study because they see collaboration toward a common goal as especially productive for decreasing intergroup prejudice and hostility. Specifically, Allport’s (1954) “contact theory”, and its derivatives in this context, were discussed, which asserts that personal contact between members of different groups leads to less intergroup prejudice and decreases intergroup hostility. Other social psychologists have developed Allport’s work and argue that de-categorization (seeing people as individuals rather than groups) and recategorization (perceiving people from both groups as belonging to the same metagroup) are 2 additional important processes that are necessary to reduce intergroup tensions and that find support in the current investigation. The study concludes by proposing a model that describes group-identity factors, as well as other factors, contributing to the success and failure of cross-border scientific environmental initiatives in areas of regional conflict.