Progressive Desertification Research Articles

On the applicability of atmospheric water harvesting technologies on building facades: A critical review

The current climate emergency has already impacted life on Earth with increasingly extreme, prolonged, and frequent weather events. One of the most critical consequences is the progressive desertification of lands, leading to a scarcity of safe and sustainably sourced freshwater supplies. Water availability is entwined with regional economic and social benefits, as well as environmental and ecosystem security. Today, about 4.5 billion people have inadequate access to clean water, pushing to find alternative solutions for providing safe water to all. Localized atmospheric water harvesting (AWH) may represent an economical and efficient alternative, and some case studies already demonstrate its small-scale viability. Nonetheless, its large-scale applicability in urban environments and its related impacts and barriers are significantly under-explored.This paper proposes a systematic review of the main AWH technologies from the literature. It evaluates their potential for application on building façade components by identifying the technology readiness level (TRL) and undertaking a Strengths-Weaknesses-Opportunities-Threats (SWOT) analysis. Results indicate that the currently available technologies, despite their infancy on the TRL scale, offer significant potential for application at the building scale. Future research should investigate the boundary conditions necessary for AWH technologies to work in urban environments to identify a roadmap for large-scale uptake from the construction industry.

Climate Change in the Breadbasket of the Roman Empire—Explaining the Decline of the Fayum Villages in the Third Century CE*

The paper focuses on one of the most productive wheat-growing regions in the entire Roman Empire, the Arsinoite nome (modern Fayum) in Egypt. Towards the end of the third century CE, multiple formerly thriving farming villages at the edges of the district went into decline and were eventually abandoned. This paper presents a new perspective on causes of this abandonment by synthesizing existing research. The papyri as well as the archaeological record imply that irrigation problems arising simultaneously from the third century CE lay at the heart of the problem and led to the progressive desertification of formerly agricultural land. The surviving documentation allows us to trace what increasing water stress meant on the ground for the local population and what adaption strategies they undertook to deal with the degradation and desertification of their farmlands. While socio-economic factors certainly played a role in the decline of these settlements, a change in environmental conditions should be considered as well. In fact, natural proxies record a general shift in East African Monsoon patterns at the source areas of the Nile and consecutively lower Nile flood levels from the beginning of the third century on.

Climate as resource and challenge: international cooperation in the UNESCO Arid Zone Programme

ABSTRACT Perceptions of climatic challenges have changed significantly during the twentieth century. In recent decades, the question of global climate change received more attention than regional climatic challenges and the problems of arid regions. Historians have shown that persistent misconceptions and a lack of understanding of arid zones rooted in misguided colonial ideologies were propagated by United Nations (UN) initiatives such as the UNESCO (United Nations Educational, Scientific and Cultural Organization) Arid Zone Programme. Alarmist narratives of progressive desertification proliferated and put the blame on destructive local practices such as deforestation and overgrazing. This article investigates UNESCO’s interests in natural resources (section 1) and takes a closer look at the development and scientific elements of the Arid Zone Programme (sections 2 and 3). It argues that the Arid Zone Programme offered an effective framework that helped develop and spread new interdisciplinary research approaches to improve knowledge about arid zones. The myth of progressing desertification and misguided colonial expertise characterized much of its political rhetoric, but not its scientific work, which reflected balanced and more critical appraisals of out-dated colonial expertise. In its conclusion, the article suggests that broader contexts need to be taken into account to understand a resurgence of alarmist narratives of desertification such as shifting interests in climatology from local climatic issues to the global atmospheric circulation and a neglect of the climatology of arid zones.

The response of the moss Campylopus lamellatus (Leucobryaceae Schimp.) post El Niño: a case study in the Caatinga

Abstract Biological soil crusts (biocrusts) are important biological components in arid and semi-arid regions because they can serve as ecological facilitators for the vascular flora. Biocrusts of rocky outcrops of the Caatinga biome in the semiarid region of Northeast Brazil are comprised mainly of populations of the pioneer moss Campylopus lamellatus. Meanwhile, the Caatinga is undergoing progressive desertification, which is likely to continue for the next 100 years. Therefore, the physiological responses of C. lamellatus to climate change should be included in predictions regarding the future of the flora of these rocky environments. We evaluated a population of C. lamellatus during a prolonged drought brought about by El Niño, and during the first subsequent rainy season. We used biomass (dry mass) and proportion of chlorophyll as measures of tolerance. We identified decreased investment in biomass allocation and the degradation of photosynthetic pigments during the drought event. In contrast, we observed a rapid increase of chlorophyll during the rainy season, which represents biomass investment via chlorophyll regeneration. We conclude that the resilience of C. lamellatus is rapid, even for a photophilic plant, and should ensure its facilitative function under conditions of water saturation of the environment.

Transitions in Palaeoecology and Technology: Hunter-Gatherers and Early Herders in the Gobi Desert

The desert and arid steppes of Mongolia and northern China were geographically central to the spread of pastoralism and the rise of pastoralist states, but research on the organizational strategies of pre-pastoralist hunter-gatherers and the spread of herding has been extremely limited. Until recently, catalogues of sites collected by Westerners in the 1920s and 1930s comprised the body of English-language publications on Gobi Desert prehistory. This article introduces a wealth of new site-specific and interpretive data, drawing on English-language sources as well as Russian- and Mongolian-language publications to create a synthesis for the prehistory of the Gobi Desert from the end of the Last Glacial Maximum to the adoption of herding. Special emphasis is placed on the relationship between a major shift in desert ecosystems, comparable to the ‘greening of the Sahara’, the establishment of an oasis-based broad-spectrum foraging strategy, and progressive desertification and deforestation after 2000 BC. We conclude that an oasis-based adaptation was contemporaneous with the expansion of forests and wetlands and persisted throughout the early stages of herding. A major decline in these economies occurs after 1000 BC, in conjunction with continuing trends towards heightened aridity and major societal changes across Northeast Asia. The persistent co-existence of Bronze Age burials and microblade-based habitation sites around oases, as well as similarities in material culture, suggest that these groups overlapped geographically or were the same entity.

Terra Nova, Tamera, and the Healing of Love: Viable Pathway for a Planetary Tikkun?

Terra Nova, Tamera, and the Healing of Love: Viable Pathway for a Planetary Tikkun?

The problem of utilization the water resources of the Republic of Iraq under progressive desertification conditions

On the basis of a comprehensive analysis of the water resources utilization in the Republic of Iraq under progressive desertification conditions, the conclusion is drawn about the need to undertake measures for rationalization of fresh water usage in view of its shortage in the external sources: rivers, lakes, and bogs. The most important measures include the organization of drip irrigation and irrigated agriculture, the construction of dams intercepting flood waters, and the tapping of subsurface waters in droughty provinces. It is also necessary to restitute the international regulations concerning the equitable distribution of the transboundary waters within the drainage basins of the Tigris and Euphrates rivers.

Evaluation and Modeling of Microbial Population Dynamics of Degraded Sandy Quarry for Their Rehabilitation and Revegetation

Our study was conducted in the sandy quarry of Terga located at the mouth of Wadi EL Malah in the wilaya of Ain Témouchent (northwest coast of Algeria). This region has a major problem of soil degradation which often leads to the abandonment of large farmland areas and a form of progressive desertification of the environment. To rehabilitate soils and landscapes degraded of this area ,our research is proposed to identify and study the activity of microbial population by comparing the results to the soil environment characterization and found that the soil is very poor of nutrients, organic matter (less than 1%) in the presence of an alkaline (pH greater than 9). These adverse conditions hinder the development of microbial flora essential for growth and plant nutrition soil.

Factores, predicción e implicaciones en la asignación de usos de suelo : revisión y reflexiones

The recent researches on the land uses are related to the interest that are receiving in the last years the ecosystems monitoring and ecological processes modelling, specially as a result of the constant urbanization, afforestation and progressive desertification that are affecting many countries, and with the objective to consolidate suitable policies of land management and resource conservation. Land use distribution results from the link between the ecosystems and the human action, which is often unbalanced and unpredictable. Theories and models look for significant indicators that show the landscape conditions, pressures and social claims. This paper is a bibliographical revision of some scientific studies by means of which several excellent aspects are introduced to have them in account in the landscape management and in the efficient allocation of land uses.

Sensitivity of natural vegetation to climate change in the Euro-Mediterranean area

This study explores the sensitivity to future climate change of natural vegetation patterns in the Euro-Mediterranean area under the IPCC-A1B emission scenario, using a dynamic vegetation model forced by fully coupled high resolution regional ocean-atmosphere model simula- tions. Our results indicate that a future warmer climate could not only affect the regional terrestrial carbon cycle, but also significantly impact vegetation dynamics. Specifically, by 2021-2050, temper- ate deciduous vegetation is projected to replace boreal and grass vegetation in parts of northeastern Europe, while in North Africa, simulations show a progressive desertification. The changes in domi- nant vegetation are mainly related to the increased drought stress on vegetation and the enhanced fire frequency. As for the carbon cycle, large increases in net primary production (NPP) are found in northern Europe resulting from higher temperature and precipitation, as well as higher atmospheric CO2 levels. In contrast, smaller NPP increases are found in the Mediterranean region, where reduced precipitation and increased temperature leads to an increase in drought years and, hence, water- stress for vegetation.

Proposed policies for integrated watershed management in order to combat desertification in Euphrates and Tigris basin

Desertification of the arid and semi-arid lands of the world has been proceeding for more than a thousand years.Human-induced degradation in these areas is regularly cited as one of the principal causes of desertification.Euphrates and Tigris Basin as the case study of this research in some aspects is almost unique in the world. But thisbasin has been confronted to progressive desertification. This research was done for proposing appropriate policies interms of main driving forces in order to combat desertification in this basin. So qualitative analyses of data banks ofthe countries involved in this basin have been collected by FAO consultants, showed desertification in Euphrates andTigris Basin is characterized by climate factors and human activities; water scarcity and unequal distribution of waterare major climate factors. The main human activities are overgrazing of rangelands, deforestation, and land usechanges. Because of negative impacts of human activities on climate factors and also deep dependency of livelihoodin this basin, there is an urgent need to plan an integrated watershed management in order to managing people, water,forests, and range lands together for combating this progressive desertification.

Vegetation pattern variation, soil degradation and their relationship along a grassland desertification gradient in Horqin Sandy Land, northern China

The Horqin Sandy Land is one of the most severely desertified regions in northern China. Plant communities and soil conditions at five stages of grassland desertification (potential, light, moderate, severe and very severe) were selected for the study of vegetation pattern variation relating to soil degradation. The results showed that vegetation cover, species richness and diversity, aboveground biomass (AGB), underground biomass, litter, soil organic carbon (C), total nitrogen (N), total phosphorus (P), electrical conductivity, very fine sand (0.1–0.05 mm) content and silt (0.05–0.002 mm) content decreased with the desertification development. Plant community succession presented that the palatable herbaceous plants gave place to the shrub species with asexual reproduction and sand pioneer plants. The decline of vegetation cover and AGB was positively related to the loss of soil organic C and total N with progressive desertification (P < 0.01). The multivariate statistical analysis showed that plant community distribution, species diversity and ecological dominance had the close relationship with the gradient of soil nutrients in the processes of grassland desertification. These results suggest that grassland desertification results in the variation of vegetation pattern which presents the different composition and structure of plant community highly influenced by the soil properties.

Response of vegetation and soils to desertification of alpine meadow in the upper basin of the Yellow River, China

Alpine meadow plays important roles in the animal production and conservation of water resources in the upper basin of Yellow River. In recent decades, desertification of this alpine meadow has resulted in changes in vegetation and soil features, as well as threatening the ecosystem functions and security. A field study was conducted to explain the response of vegetation pattern and soil features to desertification of alpine meadows. Results of vegetation studies indicated that hygrophytes were gradually replaced by mesophytes, xerophytes, and some annual psammophilous plants, and that cover and herbaceous biomass decreased along with the progressive desertification. Vegetation height increased in the slightly desertified stage, and then decreased in the very severe stage. Species diversity decreased, suggesting that desertification of alpine meadow contributedto species loss. This study also indicated that soil features gradually declined with increasing desertification of alpine meadow with soil texture becoming coarser and water content decreasing gradually. Soil bulk density (0–20 cm layer) increased with increasing desertification, but in the deeper soil (20–40 cm layer) decreased from original vegetation to the moderately desertified stage, and then increased after the severely desertified stage. The difference between the topsoil and the deeper soil in both soil bulk density and soil moisture was greatest at the moderately desertified stage. Soil organic matter dramatically reduced with progressive desertification. Soil nutrients (total N, P and K) decreased greatly due to desertification. Soil pH (0–20 cm and 20–40 cm) showed no significant differences among desertification stages. Overall, desertification of alpine meadow decreased plant diversity, reduced dominance of palatable species and changed soil physical and chemical properties. Correlation analysis indicated that vegetation change has been regulated by soil texture, soil organic matter and soil water.

Natural Minerogenic Dust and Human Health

Natural Minerogenic Dust and Human Health

Mobility and kinship in the prehistoric Sahara: Strontium isotope analysis of Holocene human skeletons from the Acacus Mts. (southwestern Libya)

The origins and development of pastoralism in Saharan North Africa involves societies and economies that, subjected to profound climatic changes and progressive desertification, came to be based on the movement of people and resources. The extreme conditions to which these groups were subjected made mobility a ‘resource’ in itself. Through the first analysis of Sr isotopes ( 87Sr/ 86Sr) in dental enamel of human skeletons from prehistoric burials of the Fezzan (southwestern Libya), we begin to investigate how mobility patterns changed with the onset of the desert. In combining our results with the archaeological evidence, we find that, the transformation in the economy of prehistoric groups correlated with a shift in mobility and possibly kinship systems.

Micro-scale spatial heterogeneity and the loss of carbon, nitrogen and phosphorus in degraded grassland in Ordos Plateau, northwestern China

The micro-scale spatial distribution and loss of carbon, nitrogen and phosphorus were examined in degraded grassland near Ordos, in the Mu Us Sand-land, northwestern China. Five communities that represented a series of successionally degraded stages in desertification were chosen for the work. The dominant plant of Community 1 was the steppe grass Stipa bungeana; Community 2 was dominated by a mix of S. bungeana and the shrub Artemisia ordosia; Community 3 was A. ordosia; Community 4 was a mix of A. ordosia and the desert grass Cynanchum komorovii; and Community 5 was C. komorovii. The soils in root-spheres and in the bare openings between plants in five successionally degraded plant communities were analyzed for total organic carbon (TOC), total nitrogen (TN), inorganic nitrogen (IN), total phosphorus (TP), and available phosphorus (AP). The results showed that the heterogeneity process of the soil chemistry was characterized first by TOC heterogeneity and later by TN heterogeneity. The heterogeneity process of TP was only characterized in the community 3. No significant heterogeneity was present for AP in the five community stages. At the beginning of degradation, invasion by the shrub A. ordosia of S. bungeana grassland was found to lead to competition for soil elements between S. bungeana and A. ordosia and made the Community 2 soil environment temporarily homogeneous. In Community 3, however, the soil elements became spatially heterogeneous, and this led to the development of `islands of fertility'. The concentrations of soil elements (TOC, TN and IN) were greatest in the shrub root-spheres. With further desertification (from Community 4 to Community 5), the islands of fertility began to collapse, and the concentrations of the main soil elements declined rapidly. The dynamics of soil phosphorus under progressive desertification were different from those of the other soil elements. TP decreased from form Community 1 to Community 5, while the AP concentration did not change in mid-level desertification (Community 3), but increased with serious desertification (Community 5).

Rock art conservation in Morocco

The state of preservation of archaeological sites in Southern Morocco is discussed, with particular reference to rock art sites. While the archaeological community is aware of the scale of the damage (both natural and anthropic) to archaeological sites in the central Sahara, the deterioration of Moroccan cultural heritage is still largely unreported. In May 2002, a survey of some rock art sites in the pre-Saharan Morocco, in the Jebel Sarhro, revealed the gravity and extent of the destruction, caused mainly by looting, vandalism and re-utilisation of archaeological material. Many of the activities detrimental to the rock art can be understood if read into their socio-economic context. Pre-Saharan Morocco is poor and suffers from progressive desertification; the traffic in cultural objects represents one of the few available revenue sources. As a consequence, rock art and other cultural artefacts are systematically looted and sold to private art collectors and tourists. Apart from the scientific damage, this impoverishes the local population, which will lose a great cultural patrimony upon which they could potentially build a sustainable tourism industry. The suitability of management strategies for archaeological sites will also be re-examined, in the light of the actual needs of the local communities. This means defining the role of archaeologists (and other outsiders) in the decision-making process. The dilemma is whether we should consider certain activities – the addition of new engravings to rock art sites or the reutilization of decorated boulders for the construction of water basins – as harmless or detrimental. Do Western values entitle archaeologists to force their management plans on local communities? In this perspective, the paper reports damage done to several engravings by an archaeological team making moulds. What should archaeologists be allowed to do in the name of science and conservation?

The role of low-quality irrigation water in the desertification of semi-arid zones in Murcia, SE Spain

The reuse of poorly purified and industrial waters in semiarid areas may have a harmful effect on the environment and lead to progressive desertification. We have studied the spatial-temporal variability of the chemical characteristics of the soils in an area recopying approximately 138 km 2, from Southeast Spain (Murcia), which is contaminated using highly saline irrigation water. Soil samples were taken from 18 selected locations and then resampled after an interval of 3 years. The results show that salinisation and, occasionally, alkalinisation increased with increasing salt concentrations of the water used. The study of the water-soluble ions present in the soils allows to determine the main factors influencing these processes. A statistical study proves that changes in the salinity of the waters used for irrigation, agricultural practices, the use of fertilisers, and salts supplied by runoff of the surrounding areas are the essential factors that have led the soils to their actual condition.

The rock varnish in the Messak Settafet (Fezzan, Libyan Sahara), age, archaeological context, and paleo-environmental implication

The manganese-rich rock varnish from the Messak Settafet plateau is a relict feature that developed at the end of the Holocene humid cycle, before the onset of the present-day hyperarid conditions. The Messak Settafet varnish consists of three microlayers of different composition and micromorphological features. The innermost microlayer is composed of illuvial clay. The second, middle microlayer is the classic manganese-rich rock varnish. The outermost microlayer is composed of unaltered aeolian dust. Each microlayer formed under different climatic conditions, and the microstratigraphy records a climatic evolution from a wet environment towards progressive desertification. The relationship between desert varnish, rock engravings, and radiocarbon-dated archaeological evidence and the comparison with the Holocene climatic evolution as from cave deposits suggest that most of the varnish developed since the end of the VI millennium B.P. under a semiarid climate characterized by steppe-type vegetation, up to the onset of desert conditions, during the IV millennium B.P. © 1996 John Wiley & Sons, Inc.

The influence of coastal utilisation by man on the presumed extinction of the Canarian black Oystercatcher Haematopus meadewaldoi Bannerman

There is no material evidence for the survival of the endemic Canarian black oystercatcher Haematopus meadewaldoi of the Canary Islands subsequent to 1913. An expedition to the eastern Canary Islands in 1985 failed to find any trace of the bird, and likely factors contributing to the species' extinction were investigated. There has been a progressive desertification of the eastern Canary Islands in the past few centuries, accelerated more recently by changing land-use practices. This has led in turn to an increased dependence of the islands' inhabitants on marine resources as food, with concomitant modification of intertidal invertebrate communities. Habitat availability was the ultimate factor limiting population size in H. meadewaldoi, but the extinction of the species was probably precipitated by increasing disturbance and competition with man for food.