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In Monte Desert, one of the most arid regions in Argentina, there is an important hydrocarbon basin and the main shale oil reservoir in South America. An intense oil activity takes place there through rock fractures, where failures and spills can occur. Loss of hydrocarbons due to high pressure conditions, produce emissions into the air in the form of sprays that can be deposited in large areas on the ground (blow outs). In samples of uncontaminated soil and soils affected by a blow out event we evaluated seed germination under laboratory conditions of keystone species: Larrea divaricata Cav. and Pappostipa speciosa (Trin. & Rupr.) Romasch. In uncontaminated controls, germination probabilities varied between 0.55 and 0.66 for L. divaricata and between 0.76 and 0.86 for P. speciosa. In contrast, in contaminated soils, germination probability was significantly lower for both species: 0.01–0.02 for L. divaricata and 0.2–0.25 for P. speciosa. We conclude that the presence of hydrocarbons significantly decreases germination of the studied species. Therefore, natural regeneration in arid regions can be seriously affected by hydrocarbon spills. • Hydrocarbons that are deposited on the ground can severely reduce germination. • Different fractions of hydrocarbons have the same detrimental effect on germination. • The negative effect on germination can affect both perennial shrubs and herbs in arid regions. [ABSTRACT FROM AUTHOR]

Dryland rehabilitation in the central arid region of Argentina is urgently needed to reverse the current high levels of degradation. Neltuma flexuosa var. depressa , adapted to arid environments, gives it the potential to be used in rehabilitation, for extensive livestock grazing and apiculture. When the soil seed bank is exhausted and natural regeneration is impossible, seed-based rehabilitation programmes constitute one of the more promising options. Thornless ecotype selection could improve pods utilization, so studies of the population distribution can be useful as a genetic resource for pre-breeding. Niche occupancy exhibits a large latitudinal extension (32–43°S), mainly in areas of salinity. All populations would have a transient soil seed bank, but seed dormancy release was lower in populations originating in more unpredictable environments, which distributes germination across years and acts as a bet-hedging strategy between seasons. We observed differences between the populations, with greater spinescence being associated with higher isothermality and lower annual precipitation (r > 80***) at the population's place of origin, showing local adaptation. We also found some thornless seedlings (1.67%) in a population with lower spinescence. However, the plastic response of thorns in seedlings, as well as later stages, should be evaluated in stressful environments. • Neltuma flexuosa var. depressa had a transient soil seed bank. • We evaluated the ecological and phenotypic characterization of 26 native populations. • High seed dormancy and plant spinescence were associated with drier environments. • We detected thornless seedlings, a desirable trait for pre-breeding programmes. [ABSTRACT FROM AUTHOR]

Abstract: While numerous studies focus on heterogeneity created by living plants and animal diggings in arid lands, little information exists on the pattern and role of heterogeneity created by large woody debris. We studied soil nutrient content, volumetric water content, and vegetation associated with the presence of logs in sites subject to different grazing intensity in a chenopod shrubland of South Australia. Soil volumetric water content was lower close to logs, and the soil there dried faster after rains. Organic carbon was higher, but available phosphorus was lower in soil associated with logs. We documented greater seedling emergence, species richness and diversity, and greater annual plant biomass next to logs. Our results were similar in the sites with high and low grazing pressure, the latter having higher numbers of seeds and species in the germinable soil seed bank. Logs in this system create patches that differ in properties from other patches in the system (i.e. those created by perennial plants, depressions, or diggings). Logs constitute a unique microenvironment which affects the plant community structure and may enhance the diversity of the system, and should be considered in management schemes. [Copyright &y& Elsevier]

Abstract: We address the idea that donkey''s gut passage and dung could increase seed germination and seedling growth of Prosopis laevigata. This species is a useful plant in a Mexican inter-tropical desert, where land use change and habitat fragmentation are currently affecting P. laevigata shrublands. We conducted greenhouse experiments in which seeds ingested by donkeys and non-ingested seeds were placed in dung pats or soil. Results suggested that gut passage and dung did not have significant effects on seed germination. On the other hand, dung significantly increased the height and dry weight of P. laevigata seedlings. Information about the effects of donkeys on seedling establishment could be used to promote the natural regeneration of this plant species. [Copyright &y& Elsevier]

Abstract: Studies on breeding parameters in peripheral populations have been centred on species with stable or regressive ranges. However, the studies on peripheral expanding populations are few, probably due to the scarcity of suitable models. On the other hand, islands are a sort of peripheral populations with their own rules. By using an arid-land passerine, the Trumpeter Finch, we compare the clutch size between two peripheral populations, one in expansion located in south-eastern Iberian Peninsula, another located in Fuerteventura, Canary Islands, with the clutch size of their presumably source population, Northwest Africa. We did not find differences in clutch size between continental peripheral population nor island one compared with North African one. We also present other breeding parameters including incubation period, hatching rate, nestling period, fledgling rate and productivity in both peripheral populations. [Copyright &y& Elsevier]

Abstract: The complex interactions between human activity and natural processes determine non-linear dynamics in ecosystems that can difficult their management. Human settlements in arid lands contribute to the modification of disturbance regimes, including the introduction of new disturbances and the elimination of others. In consequence, they can alter the functional mechanisms that allow systems to overcome limiting factors, leading to desertification. In this revision, we evaluated the effects of the changes on disturbance regimes produced by the different forms of land transformation on the structure and function of ecosystems of the Monte Biogeographical Province, in Argentinean arid west. Two approaches were used: the analysis of land use history and the analysis of the effects of the main disturbances on the dynamics of different communities. We concluded that throughout the history of the Monte Desert, the joint action of natural and anthropic agents has resulted in complex dynamics that lead most area of the Monte to a moderate to severe status of desertification. The modification of the disturbance regime had strong consequences for several aspects of the dynamics of communities, such as species composition and diversity, water dynamics, soil conditions, trophic structure and productivity of Monte Desert ecosystems. However, disturbance regimes could be managed to promote favorable transitions in ecosystems and, therefore, could be a tool for optimizing productivity of agro-ecosystems, and recovering and conserving natural ecosystems. [Copyright &y& Elsevier]

We analyzed the influence of land use and water physical-chemical characteristics on the trait composition of benthic macroinvertebrates in arid-land streams of North-East Algeria. Macroinvertebrates were sampled in the spring season of 2015, 2017 and 2018 at 36 sampling sites distributed along 5 streams of the Belezma biosphere reserve. Samples were taken from the various substratum types using a Surber net. Most of the variability of the trait-environment relationship was explained by increasing temperature and conductivity along the downstream gradient. Whilst agriculture at higher elevations did not have a great influence on the functional trait composition of macroinvertebrate communities, agriculture and urbanization at lower elevations generated significant deviations from predictable functional structures. Owing to the natural downstream decrease in community diversity in streams of the study region, entire taxa and/or functional groups were more likely to be wiped out in response to anthropogenic perturbations at lower elevations. Despite human activities, climate-related variables in arid lands play a major role on hydrological regimes that effect instream habitats, water chemistry, and macroinvertebrate communities. Given the environmental constraints in arid-land streams of North Africa, even slight increases in anthropogenic pressure can have negative effects on the taxonomic and functional composition of macroinvertebrate communities. • Arid-land streams lack a trait-environment framework to inform management plans. • Functional traits of benthic macroinvertebrates indicate ecosystem health. • Natural temperature and conductivity mostly explained trait-environment relationships. • Even slight anthropogenic pressure generates deviations from predictable communities. [ABSTRACT FROM AUTHOR]

Abstract: The island of Abu Minqar is located near the mouth of the Gulf of Suez of the Red Sea and it is the only island in the area with rich stands of Avicennia marina mangrove. The island is highly vulnerable to damage from pollution associated with coastal activities, massive tourism development and hotel constructions along the coast of Al Ghardaqa. High resolution QuikBird satellite images were used for mapping the mangrove vegetation on the island and to establish a baseline database for future monitoring of the changes of the mangrove habitat on the island. The current total area of the mangrove vegetation on the island is 28.54 hectares (21% of the total area of the island) and is made of a single species of mangrove Avicennia marina. [Copyright &y& Elsevier]

Abstract: With water conservation efforts accelerating in arid environments, industrial wastewater is considered a candidate for reuse. We investigated the possibility of using high-TDS (total dissolved solids) blowdown water from cooling towers to irrigate common landscape plants in a desert, urban environment. Nine species (three desert legume trees, three xeric-adapted shrubs and three groundcovers) were planted in a replicate block design on a 0.2ha site. Each plant was irrigated according to water demand determined by the soil moisture deficit, with one of three water treatments: blowdown water (3.65dSm−1, 2340mgl−1), well water (0.52dSm−1, 335mgl−1) and a 1:1 blend (2.09dSm−1, 1340mgl−1). Water uptake, plant growth rates and soil salinity were monitored over a 27 month period. Irrigation rates were reduced for the final 12 months of the study to more closely match standard landscape practices. All plants grew well over the study and irrigation salinity did not have a significant effect (p>0.05) on growth or water use. Soil salinities were higher in basins irrigated with blowdown water compared to those irrigated with well water, but soil salinities did not increase significantly over time for any treatment. Soil solution salinities on the blowdown treatment were in the range of 6400–15,000mgl−1, showing that these species have considerable tolerance. The overall feasibility of reusing industrial brines to irrigate urban landscapes is discussed in light of the results. [Copyright &y& Elsevier]

Abstract: Environmental factors related to water availability that control the germination and establishment of desert annual plants are fundamental in determining the dynamics of such communities. We carried out a factorial experiment with three levels of simulated rainfall, temperature, and substrate type, and analysed the germination responses of six annual plant species from three different plant associations within the semi-arid Zapotitlán Valley, Mexico. As there is no difference in the rainfall and temperature conditions of these associations, we hypothesized that differences in substrate play an important role in the structure of these communities. Four of the analysed species showed a significant effect of interaction between substrate type and other analysed factors, while the other two species showed no effect. Therefore, observed differences in the spatial–temporal distribution of species in the Zapotitlán Valley cannot be explained solely by differences in substrate type, as substrate type acts in combination with conditions of water availability and temperature depending on the requirements of individual species. The dispersion capacities and biotic interactions of different species should also be considered in such an analysis. Therefore, to determine the structure and dynamics of annual plant communities in such an environment requires monitoring of year-to-year variations in rainfall, and temperature in the context of a heterogeneous micro-topographic framework in which different soil types form a complex mosaic. [Copyright &y& Elsevier]

Field experiments were conducted at the University of Jordan Research Station at Al-Muwaqqar village to develop a simple technique for establishing Atriplex seedlings, and to evaluate the browse production under natural precipitation compared with shrubs receiving additional harvested water. Overall survival of the transplants after three growing seasons averaged 67% under strictly rainfed conditions compared to 95% when additional harvested water of 39 mm was applied. Production of grazable browse of 3-year old shrubs averaged 380 and 1151 kg DM (dry matter) ha-1 without and with additional water, respectively. Rain use efficiency averaged 1.14 and 4.48 kg DM ha-1 year-1 mm-1 for strictly rainfed conditions and additional harvested water, respectively. Intensity of cutting had a highly significant effect on the potential of shrub regrowth. Cutting shrubs at a height of 15 and 30 cm above ground level reduced regrowth substantially, whereas cutting at 45 cm enhanced the amount of regrowth. The different cutting intensities had no significant effect on survival of the severed shrubs, which indicates the high tolerance of saltbushes to cutting or browsing. Water-harvesting contour furrows are reasonable for establishing saltbush plantations in low rainfall areas (100–200 mm). Additional harvested water in small amounts from macro-catchements had a substantial effect on shrub survival, biomass production and water use efficiency. [Copyright &y& Elsevier]

Soil and cladode relations were examined between yield and fruit quality in an 8-year-old planting of Opuntia ficus indica in a traditional farm setting in Santiago del Estero, Argentina. The plantation had a relatively high mean yield and fruit soluble solids concentration of 19.5 Mg ha-1 and 15.0%. Five fertilizer treatments: (1) control, (2) 100 kg N ha-1, (3) 100 kg ha-1 N and 50 kg ha-1 P, (4) 100 kg ha-1 N+50 kg ha-1 P+100 kg ha-1 K and (5) 100 kg ha-1 N+50 kg ha-1 P+100 kg ha-1 K+50 kg ha-1 Mg were applied to the soil of 10 plants per treatment (total of 50 plants but 4 died during the experiment). There were no significant influences of these soil applications on fruit yield or quality. Additionally correlations were examined between yield, quality (Brix, fruit firmness, % pulp) and 11 cladode nutrients and 7 soil nutrients for the 46 individual plants. The only significant positive correlations with yield were for exchangeable soil Ca concentrations and the ratio of cladode Ca/Mn. Yield was very highly significantly negatively correlated with cladode Mn and significantly negatively correlated with cladode Zn concentration. While this was surprising, given the mean Ca/N ratio of 3.95 in Opuntia vs. approximately 0.50 in field and fruit crops, the importance of Ca to Opuntia mineral nutrition seems reasonable. The significant positive Ca/Mn correlation suggests a beneficial role of Ca in mediating a slight toxic Mn effect. Fruit firmness was highly correlated with cladode K concentrations, which is reasonable given that K is the most abundant nutrient in cactus fruits. Although this local variety has excellent firmness, it will be important to examine the role of K in other very high yielding varieties which have low consumer acceptance due to low pulp integrity and firmness. While fruit yield was not correlated with cladode protein, it is nevertheless important to maintain adequate protein for regulatory processes and photosynthesis. The cladode N was highly significantly correlated with cladode Ca, Cu, K and Mn and Zn in that order. Since the N fertilization treatment did not stimulate cladode micronutrient concentrations, the high correlations between cladode N and Cu, Mn and Zn may indicate micronutrient limitations. Given the higher Ca/N and K/N ratios in Opuntia than other crops, and the highly significant correlations we observed between yield and exchangeable soil Ca, it appears that the importance of the basic mineral nutrients Ca and K have been overlooked, and that future Opuntia fruit yield/quality trials should give priority to these nutrients. [Copyright &y& Elsevier]

The objectives of this study were (a) to identify individual plants of Prosopis alba and P. pallida that could grow at near seawater salinities to use directly as clonal propagules and to establish seed orchard and (b) to analyse the population structure to aid in future germplasm collections for salinity tolerance in Prosopis. This hydroponic greenhouse study compared the growth and survival of 27 Prosopis families (seed from single mother trees) as a function of salinity from 10 to 45 dS m−1. Nine P. alba families from one saline area (provenance) near Santiago del Estero, Argentina were compared to 14 P. pallida families from six provenances in Peru and to one family each of P. alba/flexuosa from Chile, P. juliflora from Senegal, P. flexuosa from Argentina and P. ruscifolia from Argentina. The mean of the P. pallida families had a significantly greater survival (61.1% vs. 41.7%) and percentage of seedlings that grew (37.4% vs. 23%) at seawater salinities of 45 dS m−1 than P. alba. Families from P. pallida had the greatest mean growth at the highest salinity but P. alba families were ranked third and sixth from the top in growth. There were little differences in maximum height growth of the individual seedlings from these two species. For P. alba, the percentage of seedlings which survived at the highest salinity level had a lower correlation (r2=0.46) with the number of seedlings which grew at that salinity level than for P. pallida (r2=0.70). The correlation between mean family growth and maximum individual growth was lower for P. alba (r2=0.24) than for P. pallida (r2=0.49) suggesting that within P. alba, with a sufficiently high number of seedlings, it would be possible to find individuals with rapid growth rates in most families. Approximately 50 of the most rapidly growing seedlings at the highest salinity level have been repotted to be multiplied by rooting of cuttings and to serve as seed orchards for salt tolerance. Given the success in identifying rapidly growing P. alba individuals from only one provenance in Argentina, more extensive germplasm collections and testing are warranted to locate individuals with superior growth rates. Due to the previously demonstrated erect form, high biomass productivity and sweet pods in these P. pallida families in Haiti, Cape Verde, India and Peru, extensive recollections and field testing of P. pallida are warranted. [Copyright &y& Elsevier]

Apart from a decrease in total perennial plant cover, degradation of North-African arid lands is not easy to qualify. Yet, simple and comprehensive yardsticks are necessary to assess degradation. We assigned components of competitive ability (C), stress tolerance (S) and ruderality (R) to 15 common perennials of Presaharian Tunisia. We used for that purpose phyto-ecological studies, data about life-form, grazing value and demography and circumstantial data. Assigning CRS-strategies to these species improves understanding of vegetation change under increased anthropic influence, helps to conceive experiments to confirm underlying hypotheses and sheds another light on the controversy about restoring arid lands. [Copyright &y& Elsevier]

With their modest rainfall, arid regions are characterized by relatively fewer species than the better-watered biomes. But this makes it all the more important that the biodiversity that is present in arid environments be given even higher priority; for each species lost from an arid region, the percentage of loss for the region''s biodiversity is much higher than in more species-rich regions. And some species, such as bees and ants, are particularly diverse in arid habitats. Realizing the importance of biodiversity in the arid regions where they live, local people have devised numerous ways of limiting their impact. Historically, such regions have been especially subject to changes in climate, which affect productivity; these changes have often been accompanied by conflicts. The paper will describe these from various parts of the arid world, as a basis for comparison. The paper will also examine economic issues relating to biodiversity in arid lands, focusing especially on the relationship between biodiversity and various kinds of development projects. The major challenges in implementing the Convention on Biological Diversity (CBD) in arid lands lie not so much in the biology of the species concerned, but rather in the social, economic, and political arenas within which people operate. We need to build a broader constituency for conserving biodiversity, extend the responsibility for conserving biodiversity far beyond government, bring local people into the conservation movement, ensure that sufficient information is available to those who need it, restore degraded ecosystems, and stimulate far greater public support for biodiversity. [Copyright &y& Elsevier]

As elsewhere in the world, the loss of biodiversity in the Kingdom of Saudi Arabia is due above all to economic factors. This is especially true where low values are given to biodiversity and ecological functions such as rangeland and watershed protection, nutrient cycling, pollution control, soil formation and photosynthesis. The threats to ecosystem structure and function are basically the same as those which threaten species. In Saudi Arabia emphasis is given to in-situ conservation which aims to maintain and recover viable populations of wild species in nature within their known natural range. This is being achieved through a system of protected areas and captive breeding programmes. [Copyright &y& Elsevier]

Soil pockets in desert mountain habitats are extremely important, as they offer a foothold for seedlings, usually have more plant available water and thus provide a favourable habitat for plant growth in an arid surrounding. This study investigated properties of soil pockets of isolated arid mountains (i.e. inselbergs), asking the following questions:

Carbon storage in grasslands of China was estimated by the carbon density method and based on a nationwide grassland resource survey finished by 1991. The grasslands in China were classified into 18 types, which are distributed mostly in the temperate region and on the Tibetan Plateau, and scattered in the warm-temperate and tropical regions. Based on the median estimate, vegetation, soil and total carbon storage of grasslands in China were 3·06, 41·03 and 44·09 Pg C, respectively. Vegetation had low carbon storage and most carbon was stored in soils. Of the four types of regions that have grasslands, alpine region (54·5%) and temperate region (31·6%) hold more than 85% of the total grassland carbon (in both vegetation and soils) in China. Considering specific types within these two regions, three grassland types, alpine meadow (25·6%), alpine steppe (14·5%) and temperate steppe (11%) constituted more than half of all carbon stored in China''s grasslands. In general and regardless of regional vegetation types, steppes (38·6%) and meadows (38·2%) made up more than 2/3 of total grassland carbon. The carbon storage in alpine grasslands may have a significant and long-lived effect on global C cycles. This study estimated more carbon storage in vegetation and less in soils than previous studies. The differences of grassland carbon between this study and two previous studies were due probably to four reasons, i.e. different estimation methods, different classification systems of grasslands, different areas of grasslands, and different carbon densities. China''s grasslands cover only 6–8% of total world grassland area and have 9–16% of total carbon in the world grasslands. They make a big contribution to the world carbon storage and may have significant effects on carbon cycles, both in global and in arid lands. [Copyright &y& Elsevier]

The matching of breeding with the food peak is one of the most important factors affecting the reproductive success in birds. Weather is known to affect the timing of breeding of many bird species. In arid lands, rainfall is usually the factor that triggers the onset of reproduction, since it commonly anticipates the peak of food through its influence on the vegetation development. In this study we used a granivorous finch (European greenfinch Chloris chloris) as a model to assess the influence of rainfall and temperature on the onset and performance of breeding. The study was carried out in fruit orchards in Guelma state (Northeastern Algeria) in 2013 and 2014. The comparison of breeding parameters between the two years showed that greenfinches delayed their breeding in the year that the rains fell later and were less abundant, produced smaller broods and had lower fledgling rate. Clutch size decreased with the season progress only this year. We discuss our results in the context of the influence of weather on bird reproduction in arid lands, while providing novel data on a farmland species from a region with little ornithological information. [ABSTRACT FROM AUTHOR]