True Desert Research Articles

Diet of the Indian fox (Vulpes bengalensis) in dry scrubland of north Gujarat, India

Indian fox Vulpes bengalensis, a mesocarnivore of the Indian subcontinent, is distributed widely in all kinds of habitats in India except the Western Ghats. The Indian fox prefers semi-arid landscapes with low rainfall where it is easy to hunt and dig dens and where the vegetation is mainly short grasslands or scrub, thorn thickets or dry deciduous forests. They mostly avoid dense forests, steep terrain, tall grasslands, and true deserts. The Indian fox is listed as of Least Concern (LC) by the IUCN and legally protected in India under schedule II of the Indian Wildlife Protection Act 1972. An opportunistic and omnivorous feeder, its diet includes insects, scorpions, centipedes, small rodents, monitor lizards and other reptiles, ground nesting birds, their eggs and fruit such as Ziziphus sp. (Rhamnaceae), Citrullus vulgaris (Cucurbitaceae), Azadirachta indica (Meliaceae), Mangifera indica (Anacardiaceae), Syzigium cumini (Myrtaceae), Melia azedarach (Meliaceae), and Ficus bengalensis (Moraceae). Some local shepherds have also reported seeing Indian foxes feed on the freshly voided pellets of sheep. Their presence and density in any area is closely related to the abundance of food.

A true desert falcon with a delayed onset of heat dissipation behaviour

The Grey Falcon (Falco hypoleucos) is a rare Australian endemic bird of prey confined for its entire life to the continent's hot arid and semi-arid zone. The prevention of hyperthermia is therefore a crucial challenge. Birds, in general, rely on a dynamic balance between physiological mechanisms and the behaviours that augment them. Effective heat dissipation behaviours in birds include panting, airing and shade-seeking. These behaviours are readily observable in the field. We observed Grey Falcons, Peregrine Falcons (F. p. peregrinus and F. p. macropus) and Saker Falcons (F. cherrug) in the wild (from continuous webcam video for the latter two species) and compared their heat dissipation behaviours in relation to air temperature, exposure to direct solar radiation, wind speed, and relative humidity. Our results show that the desert-living Grey Falcon has a considerably higher heat dissipation behaviour threshold than the two non-desert Falco species. We show that this leads to the prediction that Grey Falcons should have reduced average activity levels in key aspects of their lives, throughout the year, relative to their congeners.

The Cytotoxic Effect of the Extract of Anchusa strigosa (Him Him) Grown in Jordan Against Different Cancer Cell Lines

Anchusa strigosa - prickly alkanet from Boraginaceae grows in roadsides, and fields of a broad range of habitats from mediterranean woodlands, to steppe vegetation, to true desert. It is commonly known as" him him" or "lisan al thawr". Anchusa can withstand hard weather conditions and hence is widely cultivated. The color of its flowers can range from pure white to deep cobalt blue. Various parts of A. strigosa are used in traditional medicine for treating several diseases or symptoms, such as abdominal pain, bronchitis, cough, and diarrhea. The goal of this study was to examine the cytotoxic effect of the crude extract of A. strigosa roots and leaves and their fractions against various tumor cell lines: adenocarcinoma MCF-7, human breast ductal carcinoma T-47D; human breast carcinoma MDA-MB-231; and colorectal carcinomas Caco-2. In conclusion the antiproliferative effect was assessed by SRB assay where it showed that the phytochemical constituents in the leaf part of the plant (A. strigosa) do have more potential in depressing the proliferation rate of the cell lines than the root part.

Bacterial Communities on the Surface of the Mineral Sandy Soil from the Desert of Maine (USA).

The Desert of Maine, not a real desert, is a 160,000 m2 tourist attraction of glacial silt which resembles a desert, surrounded by a pine forest in the state of Maine located in the northeastern USA. Though not a true desert, the soil of the Desert of Maine has a sandy texture with poor water-holding abilities, nutrient retention capabilities, and a relatively low pH value (pH 5.09). Samples from this site may be of interest to examine the bacterial diversity present on mineral sandy loam soils with an acidic pH, low concentrations of organic materials though surrounded by a pine forest, and compare it with true desert soil microbial populations. Two surface sand samples from the Desert of Maine were obtained, and pyrosequencing of PCR amplified 16S rRNA genes from total extracted DNA was used to assess bacterial diversity, community structure, and the relative abundance of major bacterial taxa. We found that the soil samples from the Desert of Maine displayed high levels of bacterial diversity, with a predominance of members belonging to the Proteobacteria and Actinobacteria phyla. Bacteria from the most abundant genus, Acidiphilium, represent 12.5% of the total 16S rDNA sequences. In total, 1394 OTUs were observed in the two samples, with 668 OTUs being observed in both samples. By comparing Desert of Maine bacterial populations with studies on similar soil environments, we found that the samples contained less Acidobacteria than soils from acid soil forests, and less Firmicutes plus more Proteobacteria than oligotrophic desert soils. Interestingly, our samples were found to be highly similar in their composition to an oak forest soil in France.

Community structure of tenebrionid beetles in the Ulan Buh Desert (Inner Mongolia, China) (Coleoptera: Tenebrionidae)

Tenebrionids are a conspicuous faunal component of Central Asian deserts, but little is known about their community ecology. We investigated how tenebrionid community structure varied along a vegetational gradient in the Ulan Buh Desert (Gobi Desert). Sampling was done with pitfall traps in three sites with different vegetation cover. Species abundance distributions were fitted by the geometric series model, which expresses the “niche pre-emption” hypothesis. Community structure was investigated using different measures of diversity (number of species, Margaleff richness and Shannon-Weaner index), dominance (Simpson and Berger-Parker indexes) and evenness (Pielou’s index). The observed tenebrionid species richness was similar to that known from other Gobi Desert sites. The three investigated sites have similar species-abundance patterns, but the most dominant species varied among them. This suggests that the local environment operates a filtering action on the same basic fauna, allowing different species to dominate under different conditions. Overall, the highest total abundance was observed in the true desert site, however this site had a community structure similar to that observed in the site with more vegetation. By contrast, the investigated site with intermediate conditions showed a higher diversity and evenness, and a lower dominance. Thus, intermediate conditions of plant cover favour tenebrionid diversity, whereas a dense cover or a very sparse cover increases the dominance.

The Cataglyphis Mahrèsienne: 50 years of Cataglyphis research at Mahrès

Every year since 1969, research groups from Zürich have spent the summer months in the barren sandy areas around the Tunisian village Mahrès to study the navigational behaviour of Cataglyphis desert ants, its sensory underpinnings, and ecophysiological settings. From the 1990s onwards, researchers from other countries were invited to join the Zürich group, so that Cataglyphis increasingly advanced to become a model organism for the study of animal navigation. Its cockpit became the focus of a dynamic research system, an 'epistemic thing', as modern parlance in the philosophy of science has it. Investigations aimed at the ants' compasses and odometers, at path integration, view-based landmark guidance, and how information from these various navigational routines is combined in computing the courses to steer. In this multifaceted work, the researchers' familiarity with the site, with Mahrès, and its local geographical and historical conditions, has been essential. The essay briefly retraces the historical development of this research system. After the system had been firmly established at the North African Mahrès site, it was extended to the ecological equivalents of Cataglyphis in other true deserts of the world, to Ocymyrmex in the Namib Desert of southern Africa, and to Melophorus in central Australia.

Flávio Ferreira Pinto de Resende (1907–1967): A portuguese scientist and hero‐botanist, and his forays into systematics

Flávio Ferreira Pinto de Resende (1907–1967): A portuguese scientist and hero‐botanist, and his forays into systematics

Examination of the Bacterial Biodiversity of Coastal Eroded Surface Soils from the Padza de Dapani (Mayotte Island)

ABSTRACTTo better understand microbial populations present in atypical soil environments, and to discern any relations between these environments and their bacterial communities, we examined the “Padza de Dapani” on the island of Mayotte off the east coast of Africa. This area is not a true (hot) desert, but resembles one in many places due to extensive soil erosion. We collected surface soil samples from five different sites of the Padza de Dapani in Mayotte. We examined bacterial biodiversity using pyrosequencing of PCR-amplified 16S V1–V3 rDNA sequences from total extracted DNA. Our results show that in the acidic (pH 4.6–6), oligotrophic (organic carbon; 0.1–0.7 g/kg of soil) and mineralized (Fe: 18 g/100 g; Al: 12 g/100 g) Dapani Padza soil samples, members of the Actinobacteria and Proteobacteria phyla dominated the bacterial communities, as was also observed in samples from Saudi Arabia hot desert sands.Interestingly, members belonging to the genera Acinetobacter, Arthrobacter and Bacillus were also found to be very abundant in our samples. These were also seen in hot Asian deserts sand samples, such as those from the Gobi (Mongolia) and Taklamaken (China) deserts, thus possibly pointing to microbial populations characteristic of denuded soils.

Differential effect of shade, water and soil type on emergence and early survival of three dominant species of the Atacama Desert

AbstractUnderstanding the regeneration niche of species may allow us to gain insight into how communities are structured. In deserts, the regeneration niche is usually related to spaces beneath shrubs where shade cast by shrubs creates microenvironments that benefit seedlings and where even small amounts of rain may favour germination and establishment. Shade and water may also interact with different types of soils. However, species may have different requirements for germination and seedling survival. We could expect that shrub species with different drought tolerances exhibit different responses to the combination of these factors. We ask if responses of dominant species of the Atacama Desert to abiotic factors (shade, water and soil type) are related to their drought tolerance, a topic not exhaustively explored in shrubs growing in true deserts. We conducted two factorial experiments. The first one was designed to evaluate how shade (microhabitat) in combination with water may affect germination (emergence) and early survival. In the second experiment, we assessed the influence of shade in relation to soil type. Each species responded distinctively to the three variables under study, but in general, their emergence responses were more influenced by water (more water, greater emergence) than by microhabitat or soil type. Survival was influenced both by microhabitat and by water and was higher under shade and abundant water. Soil type affected only one of our species in terms of emergence. Species responses in general depended on their tolerance to stress. In one species, there was indication of a seed–seedling conflict. Our results show similar species responses to environmental constraints but also more or less unique responses that are related to their tolerance to drought and which may ultimately permit species coexistence. We found that shade may not be important for germination but may be crucial for survival in dry years.

Genetic analysis shows low levels of hybridization between African wildcats (Felis silvestris lybica) and domestic cats (F.s.catus) in South Africa.

Hybridization between domestic and wild animals is a major concern for biodiversity conservation, and as habitats become increasingly fragmented, conserving biodiversity at all levels, including genetic, becomes increasingly important. Except for tropical forests and true deserts, African wildcats occur across the African continent; however, almost no work has been carried out to assess its genetic status and extent of hybridization with domestic cats. For example, in South Africa it has been argued that the long-term viability of maintaining pure wildcat populations lies in large protected areas only, isolated from human populations. Two of the largest protected areas in Africa, the Kgalagadi Transfrontier and Kruger National Parks, as well as the size of South Africa and range of landscape uses, provide a model situation to assess how habitat fragmentation and heterogeneity influences the genetic purity of African wildcats. Using population genetic and home range data, we examined the genetic purity of African wildcats and their suspected hybrids across South Africa, including areas within and outside of protected areas. Overall, we found African wildcat populations to be genetically relatively pure, but instances of hybridization and a significant relationship between the genetic distinctiveness (purity) of wildcats and human population pressure were evident. The genetically purest African wildcats were found in the Kgalagadi Transfrontier Park, while samples from around Kruger National Park showed cause for concern, especially combined with the substantial human population density along the park's boundary. While African wildcat populations in South Africa generally appear to be genetically pure, with low levels of hybridization, our genetic data do suggest that protected areas may play an important role in maintaining genetic purity by reducing the likelihood of contact with domestic cats. We suggest that approaches such as corridors between protected areas are unlikely to remain effective for wildcat conservation, as the proximity to human settlements around these areas is projected to increase the wild/domestic animal interface. Thus, large, isolated protected areas will become increasingly important for wildcat conservation and efforts need to be made to prevent introduction of domestic cats into these areas.

Deficiencies in the Briske et al. Rebuttal of the Savory Method

Clinging to past viewpoints and techniques based on a lim- ited and small subset of knowledge on the subject of range- land grazing management is not helpful. The knowledge base used by Briske et al. 1 stems from a very poor understanding of Holistic Planned Grazing and poorly executed grazing ex- periments (see the work of Teague et al. ). 2 To make sweeping statements such as “The Savory method cannot green deserts or reverse climate change” is particularly misleading. It ig- nores the fact that many ranchers operating in low rainfall areas from 10 to 15 inches, areas so bare of vegetation that most people would call them deserti ed, have managed to restore vegetation, ecosystem function, and productivity us- ing Holistic Planned Grazing when even complete removal of livestock had failed to achieve any restoration. Only if the comment refers to true deserts receiving almost no rainfall would the statement possibly be true. DOI: 10.2458/azu_rangelands_v35i6_teague

Classification of arid lands, including soil degradation and irrigated areas, based on vegetation and aridity indices

It is preferable to prepare internally consistent maps of arid regions on a global scale in order to understand the present conditions of arid regions, especially deserts and soil degradation areas. We attempted to delimit arid regions at a global scale by combining climate data, i.e. aridity index (AI), and vegetation data, i.e. vegetation index. The annual AI was estimated by the ratio of mean annual precipitation to mean annual potential evapotranspiration, using the Thornthwaite method. The long-term mean of yearly maximum normalized difference vegetation index (NDVIymx) was used as an indicator of the vegetation condition. Arid regions of the world were classified into four categories, namely A, severe deserts, where both aridity and vegetation indices are very small; G, semi-arid regions, where the vegetation index is proportionally related to the AI; I, irrigated areas and oases, where the vegetation is relatively abundant despite severe dryness; and S, soil degradation areas, where the vegetation is poor despite relatively humid conditions. The Sahel from Niger to Chad, the Sahel in Darfur, and the Ordos Plateau in China are within Category S. The standard deviation of NDVIymx is very small/large in severe deserts/semi-arid areas, respectively. Thus, the Sahara desert was clearly distinguished from the Sahel; the latter belongs to Category G and drought occurs frequently here. In Category S zones, the standard deviation of NDVIymx is relatively small compared with that within the Category G zone because the return rainfall does not seem to promptly restore productivity. Category S was divided into three subdivisions according to the degree of degradation, expressed by the ratio of the AI to vegetation index. Category G was also divided into four classes, according to degree of vegetation (or aridity). The distribution of Category S is comparable to the soil degradation areas mapped by Global Assessment of Human-Induced Soil Degradation (GLASOD) data. True deserts, where the standard deviation of NDVIymx is very small, were selected from the ‘severe desert’ group. Desert areas were classified as true deserts, severe deserts, grassland deserts (Category G), and soil degradation deserts (Category S).

Chemo-ecotone’s soil characteristics and their effect on the ionic content and plants distribution

The chemo-ecotone (Kamel 2003) is influenced usually by the chemical characteristic of the soil that causes the environmental gradient. The aim of the current work is to study the plants responses to overcome the high soil sodicity SAR. The impact of soil sodicity on the species distribution across the ecotone. Eleven species were selected for investigation. Soil analysis showed that SAR decreased far away from the sea gradually, causing environmental gradient. To overcome the soil salinity and sodium toxicity, the halophytes and salt resistant plants accumulated Na+ ions more than true xerophytes. All species were dependent on potassium and calcium as compatible solutes to avoid sodium toxicity. The results showed that vegetation diversity at the chemo-ecotone was controlled by soil sodicity and the ability of plants to overcome salinity. The chemo-ecotone width depended upon the ability of true desert species, Lotus hebranicus, to disperse toward the sea, as well as the true halophytes, Limonium pruinosum, toward the desert. It is concluded that the species diversity in the chemo-ecotone depends mainly on the soil sodicity as a limiting factor.

Chorological structure of the range and genetic variation of the midday gerbil (Meriones meridianus Pallas, 1773)

The midday gerbil ( Meriones meridianus Pallas, 1773) range covers a significant portion of the Eurasian arid zone. This species tends to populate sands at different stages of stabilization and is encountered in various landscapes, from steppes to true deserts, as well as hills up to 1600 m above the see level. According to our data, the yearly average air temperature within the entire range of the midday gerbil is 9 ± 5.7°e , and the average annual precipitation is 180 ± 108 mm. A wide spread of a species under diverse natural conditions is usually characterized by a significant geographical variation. Midday gerbils were found to have a great intraspecific chromosomal variation [5]. M. dahli (Transcaucasia) and M. chengi (China), both of which were earlier assigned to M. meridianus , are now considered to be independent species [9]. Modern methods of molecular and genetic analyses make it possible to study gene genealogies and reconstruct the species range history taking into account the geographical data [1, 7]. Using these approaches supplemented with chorological analysis of the midday gerbil range, we demonstrated genetic similarity of the populations from Kalmykia in Russia to Xinjiang in China and their distinctions (reaching the species rank) from the Turkmenistan‐Uzbekistan and Tyva‐Mongolia gerbils. This is a new contribution to the gerbil taxonomy and the history of biota formation in desert landscapes.

Environmental conditions and soils of natural oases in the Alashan Gobi Desert, Mongolia

Environmental conditions and soils of nine natural oases in the Alashan Gobi Desert of Mongolia are characterized. All these oases are allocated to the zones of tectonic faults, where the discharge of slightly saline groundwater takes place. The absolute heights are about 1500 m a.s.l. The oases are found on piedmont plains or in hilly areas occupied by true deserts with fragments of extremely arid deserts. With respect to geomorphological conditions, four types of oases can be distinguished: isolated (isle-type) oases, oases in large mesodepressions, oases formed in naturally ponded areas, and oases within terraced valleys. Each of these types is characterized by specific soil cover patterns controlled by the geomorphological features of the territory, the character of parent materials, and the groundwater depth. At the same time, some common soil properties are typical of all the oases. Hydromorphic soils—peat meadow-swampy soils, dark-colored nonsaline meadow soils, oasis solonchaks that developed in areas with shallow nonsaline groundwater, solonchaks with different degrees of hydromorphism that developed from mottled-colored salt-bearing Cretaceous and Paleogene deposits, and soddy alluvial (floodplain) soils—predominate in the central parts of the oases. Under conditions of deep groundwater, takyric and sandy desert soils are formed. The oases are encircled by desert ecosystems with gray-brown desert and extremely arid soils and with poorly developed stony soils that formed on the low residual mounts. In the period of the study (1991), irrigated farming was only developed within one of the studied oases. The main part of the land was used for pasturing. In some cases, the high grazing pressure led to degradation (desertification) of oasis ecosystems. A comparison of the oases studied in the Alashan Gobi with the Ekhiin-Gol oasis in the Transaltai Gobi attests to the similarity of their nature.

Diffuse vs. contracted vegetation patterns: An objective demarcation between arid and desert vegetations

Diffuse vegetation is made up of dwarf shrubs and/or perennial grasses sparsely but regularly distributed in the landscape. It characterizes Mediterranean and temperate climate steppes. Contracted, i.e., clustered, vegetation, on the other hand, refers to vegetation irregularly distributed over the landscape, concentrating in the lower parts of the topography where some runoff mitigates the overall edaphic aridity, the interfluves remaining devoid of perennials. The distribution of diffuse and contracted vegetations depends on the substrate and on the intensity of land use. But, by and large, it appears around the 100-mm isohyet of mean annual precipitation and below. Whenever there are some exceptions, these are analyzed. This concrete landscape limit occurs in all the true deserts of the world. It could therefore be considered as an objective limit between arid and hyperarid zones.

Airborne particle accumulation and composition at different locations in the northern Negev desert

Atmospheric desert dust was collected over 36 months in ground-level collectors at four stations in the northern Negev desert, Israel. Three stations (Shivta, Sede Boqer and Avdat) are located in the desert itself whereas the fourth station (Sayeret Shaked) is situated at the desert fringe, in the transition zone between the true desert and the more humid area to the north. The dynamics of the dust in the three desert stations is similar and differs from that at the desert fringe station. In the desert, dust accumulation is highest in summer and lowest in winter, whereas the situation is reverse at the desert fringe. Also, the amount of accumulation is much higher in the desert itself. No important differences are observed with respect to the average grain size of the dust, but the temporal evolution in grain size variability at the desert fringe is different from that in the desert. Mineralogical analysis by means of X-ray diffraction shows that quartz and calcite, and to a lesser extent also dolomite, are the major constituents of the Negev dust. There is a good agreement between the quartz and calcite content of the dust samples and that of the outcropping rocks located slightly upwind of the four stations, suggesting that at least an important part of the dust collected is of rather local origin. However, the regular records of dust haze events in the northern Negev show that part of the dust that accumulates in this region is not of local origin, but originates from distant sources. This dust may later mix with the local dust.

Rome without Romanization: Cultural Change in the Pre‐Desert of Tripolitania (First–Third Centuries AD)

The pre‐desert of Roman Tripolitania was one of the most remarkable regions of the empire. From the first to the sixth centuries AD it supported a thriving agricultural community, despite the marginality of the environment. The initial transformation took place at a time when Rome was actively campaigning against the tribes of the true desert. That the settlement of the pre‐desert had something to do with Roman action seems obvious enough, but paradoxically the material culture of the pre‐desert shows little direct Roman influence. This paper resolves this dilemma by arguing that settlement of the pre‐desert came about largely because of the social dynamics of its indigenous nomadic inhabitants. It is argued that Roman military success brought political stability to the pre‐desert and that this inadvertently created the conditions that enabled certain sections of pre‐desert society to abandon a nomadic existence in favour of a more sedentary one, based on agriculture. This paper explores the reasons why this took place and discusses cultural change in the Tripolitanian pre‐desert in light of these conclusions.

Desertification in Russia: Problems and solutions (an example in the Republic of Kalmykia-Khalmg Tangch)

During the second half of the 20th century Kalmykia has undergone severe desertification. Under Soviet rule, rangelands were increasingly devoted to animal production, and pastures were converted to cropland in a campaign to increase crops. Pastures were grazed two to three times their sustainable production, saiga populations and habitat greatly decreased, more than 17 million ha were subjected to wind erosion, 380,000 ha were transformed into moving sands, and 106,000 ha were ruined by secondary salinization and waterlogging. By the 1990s almost 80% of the Republic had undergone desertification, and 13% had been transformed into a true desert. In 1986 the General Scheme of Desertification Control was formulated. The scheme called for rotating pastures, reclaiming blown sand using silviculture, tilling overgrazed pastures and sowing fodder plants, and developing water supplies for pastures. In its early years the scheme has been successful. But the management of restored pastures usually reverts to the same farms responsible for the poor conditions, and there is great apprehension that degradation could reoccur. This case study concludes that the general cattle and agriculture development in Kalmykia is unviable for ecological and economic reasons, that Kalmykia should implement an adaptive policy oriented toward conservation and accommodating the interrelation and variability of land resources, that the desertification problem can be solved only by changing agrarian policy as a whole, and that a desertification control program must become an integral part of economic and social development of the Republic.

Pelagosit - neu für Israel: Seine prinzipielle Verschiedenheit vom echten Wüstenlack

Pelagosit - neu für Israel: Seine prinzipielle Verschiedenheit vom echten Wüstenlack