Search

Arid and semi-arid lands throughout the world suffer from problems like low and erratic rainfall, high temperature, low amount of nutrients and salinity/alkalinity of soil and water. In addition to that, some other factors like composition of bedrock and sea water intrusion exaggerate the problem. The paper gives information about various remediation processes like green remediation, phytoremediation, biochar application, herbal treatment for improvement in soil and water quality. In addition to these methods, some management techniques are also highlighted like water harvesting by tankas, khadin system, watershed management, check dams, the implication of Bhungroo and Zai technology, dew and rain ridge collection system, drip and sprinkler method of irrigation and soil moisture conservation practices. Due to intense heat in the region, the agriculture and farming also get affected. The plant growth-promoting bacteria (PGPR) in the rhizosphere get affected due to insufficient moisture. These PGPR help in root growth, prevention of plant disease and increase availability of nutrients. It has been found that some of the PGPR strains in the arid lands involve in the metabolism and growth of plants by withstanding the unfavorable condition. Integrated farming system and new land use technologies like agroforestry approach are used for better benefits. These techniques will result in the overall uses of resources and restoration of ecological diversity. This paper enumerates various arid regions in India, their adverse soil conditions, water management practices and possible solutions for ecorestoration of the region. [ABSTRACT FROM AUTHOR]

The aim of the study is to present some specific climatic conditions on the territory of the Republic of Serbia based on the analysis of four climate indices, which can help in understanding contemporary climate changes. Temperature and precipitation data from 31 meteorological stations for the period 1951-2010 were used. The relative homogeneity of the data series was done using the MASH v3.02 method. The indices used are: Johansson Continentality Index, Kerner Oceanity Index, De Martonne Aridity Index, and Pinna Combinative Index. Geospatial analysis of the distribution of the values of the four mentioned indices was done using the QGIS package 2.8.1. The results of the research show that the continentality effect is present in most of Serbia, while oceanity is observed locally, mainly in the western and southwestern parts of the country. The further analysis showed that there is no dry and semi-dry Mediterranean climate in Serbia. Considering that it is dry in the warmest part of the year (July-September), when the need for water is increased, which is clearly shown by the Walter climate diagram, as well as the fact that an increase in temperature and a decrease in precipitation during the vegetation period were observed in the second 30-year period (1981-2010), it can be concluded that in Serbia there is a tendency towards arid climate. The results presented in this paper can help decision makers to plan certain climate change adaptation measures. [ABSTRACT FROM AUTHOR]

This paper reflects on the themes illustrated in the 11 case studies on the archaeology of drylands. The papers emphasise the diversity of dryland forms, and of the landscapes within them, the implications of this diversity for the societies living in them, and the need to integrate palaeoenvironmental and archaeological approaches in their study. These studies recognise that how past dryland societies recognised risks and opportunities in drylands, including at times of ecological change (whether climatic and/or anthropogenic) may have been very different from our own notions of post-Enlightenment rationality. They provide examples of very different responses to aridification including: abandoning places and lifeways; specialising in alternative rhythms of life and resources; diversifying and broadening the subsistence base to spread risk; and applying new technological and social solutions to make drylands easier to live in. Whilst emphasising the challenges in both theoretical frameworks and methodologies if we are to better understand the interplay between ecological and social drivers of dryland histories, importantly they demonstrates the capacity of dryland peoples to take both wise and foolish decisions in relation to their own survival and to the sustainability of the natural resource, often with implications for their neighbours. These are lessons that resonate with the pressures on drylands and dryland peoples today. [ABSTRACT FROM AUTHOR]

Gaps in drought monitoring result in insufficient preparation measures for vulnerable areas. This paper employed the standardized precipitation index (SPI) to identify meteorological drought years and the Thornthwaite aridity index (TAI) to evaluate aridity in three provinces of northeast Thailand growing cassava and sugarcane at massive scales. Precipitation and temperature data were sourced from Global Land Data Assimilation System-2 (GLDAS-2) Noah Model products at 0.25 degree resolution and used for calculating the drought indices. This study was conducted for the period of 2004 to 2015. The SPI was computed for 1, 3 and 6 months scales to measure short- to medium-term moisture. The results indicated major meteorological drought years as 2004, 2005, 2010, 2012, 2014 and 2015. A range of 1 to 3 months of extreme rainfall shortage was experienced during each of these years, including the growing season of 2004, 2012 and 2015. TAI-based results indicated that the area experiences an average of 7 to 8 months of aridity during drought periods, compared to the historical overall average of 6 months. The spatial TAI for the major drought years indicated delayed onset, intermittency or early cut-off of the rainy season. The year 2004 was the most intense in terms of aridity. The longest duration of aridness for some areas was between 9 and 10 months in 2012 and 2014, respectively. In terms of spatial coverage, all meteorological drought years had out-of-season aridity. Based on the region's historical records, this highlighted an increase in the frequency of droughts and duration of aridity. A disturbance in the growing season has the potential to affect crop yields, hence, the need to improve and strengthen existing adaptive measures for agriculture as the main source of food and income in the northeast. [ABSTRACT FROM AUTHOR]

The objective of the paper is to analyze: a) the forest site factors, that have an impact over the plain areas within the Vrancea county, which influences the natural forest vegetation and the afforestation solutions that are to be implemented, b) and the concrete possibilities towards environmental protection and to improve the environmental conditions for agricultural lands, through establishing placement of a shelterbelt system. A selection of 33 administrative units has been considered as the working area for this study and the operations carried out were: (i) analysis of the existing forest site conditions; (ii) choosing of the most suitable forestry system; (iii) describing the forestry system’s characteristics; (iv) placement possibilities analysis; (v) building up the GIS database to a functional level; (vi) establishing the forest network of shelterbelts for field protection. The area of agricultural land for which urgent protection measures are required is of approximatively 94.958 ha (53% of the total plain area of the Vrancea county). These areas are located exclusively in the forest-steppe area and it is sparsely covered with forests, which requires the inclusion of this area in the first priority list for application of the environmental protection measures through the use of forest vegetation. Calculated forest network of shelterbelts consists of a total of 2.607 hectares (2.75% of the protected area), being distributed amongst the two identified land use categories in the following manner: 2.419 ha (93%) on arable land and 188 ha (7%) on pasture land. [ABSTRACT FROM AUTHOR]

Climate‐vegetation interaction assessments often focus on vegetation response to concurrent climatic perturbations, seldom on the time‐lag effect of climate. Here we employ global satellite observations, climate data records and CO2 flux measurements to calculate the time‐lag of vegetation response to climate. We analyze the time‐lags of various climate variables under distinct environmental conditions to gain insight into how the long‐term climatic regimes and tree cover influence the time‐lag effects. Our findings reveal that terrestrial ecosystems characterized by arid and cold climates show more concurrent climate‐vegetation interactions than other ecosystems. Whereas areas with higher tree cover and humid ecosystems with both high mean annual temperature and precipitation show substantial time‐lag response of vegetation to climate by up to 6 months. Since the global climate‐vegetation interaction is dominated by time‐lag effects, incorporating these effects is paramount to improve our understanding of vegetation dynamics under a changing climate. Plain Language Summary: When studying how climate affects vegetation, many studies usually focus on immediate plant responses, without considering the long‐term effects of climate. In our study, we used satellite data to look at how plant photosynthesis and growth changed over time in response to concurrent and past climates. We found that in dry and cold areas, plants respond quickly to changes in climate. But in regions with high tree cover and humid climate, plant responses to climate can take up to 6 months. Understanding these delays is crucial for predicting how vegetation will respond as the climate changes around the world. Key Points: Terrestrial ecosystems with higher tree cover respond to climate perturbation more slowly than grasslands and croplandsTemperature consistently has more significant impacts on vegetation in the longer term than VPD and soil moistureArid and cold ecosystems show shorter time‐lag responses of vegetation to climate [ABSTRACT FROM AUTHOR]

Improved understanding of mosquito–plant feeding interactions can reveal insights into the ecological dynamics of pathogen transmission. In wild malaria vectors Anopheles gambiae s.l. and An. funestus group surveyed in selected dryland ecosystems of Kenya, we found a low level of plant feeding (2.8%) using biochemical cold anthrone test but uncovered 14-fold (41%) higher rate via DNA barcoding targeting the chloroplast rbcL gene. Plasmodium falciparum positivity was associated with either reduced or increased total sugar levels and varied by mosquito species. Gut analysis revealed the mosquitoes to frequently feed on acacia plants (~ 89%) (mainly Vachellia tortilis) in the family Fabaceae. Chemical analysis revealed 1-octen-3-ol (29.9%) as the dominant mosquito attractant, and the sugars glucose, sucrose, fructose, talose and inositol enriched in the vegetative parts, of acacia plants. Nutritional analysis of An. longipalpis C with high plant feeding rates detected fewer sugars (glucose, talose, fructose) compared to acacia plants. These results demonstrate (i) the sensitivity of DNA barcoding to detect plant feeding in malaria vectors, (ii) Plasmodium infection status affects energetic reserves of wild anopheline vectors and (iii) nutrient content and olfactory cues likely represent potent correlates of acacia preferred as a host plant by diverse malaria vectors. The results have relevance in the development of odor-bait control strategies including attractive targeted sugar-baits. [ABSTRACT FROM AUTHOR]

Simple Summary: Climate change will cause a reduction in the provision of goods and services of Mediterranean forests, including those of stone pine (Pinus pinea), an economically important species. We used a dendrochronological approach to address climate impact on the growth of stone pine natural stands and plantations. Our results indicate that increasingly arid conditions will affect both natural stands and plantations in native and exotic countries. Adaptive management will be essential to ensure the maintenance of the stands and their multifunctionality. Pinus pinea is an important Mediterranean species due to its adaptability and tolerance to aridity and its high-quality pine nuts. Different forest types located in Mediterranean native and non-native environments provide the opportunity to perform comparative studies on the species' response to climate change. The aims of this study were to elucidate growth patterns of the species growing in native and exotic habitats and to analyze its response to climatic fluctuations, particularly drought, in both geographical contexts. Understanding stone pine (Pinus pinea) growth responses to climate variability in native and exotic habitats by comparing natural stands and plantations may provide useful information to plan adequate management under climate change. By doing so, we enhance the understanding of P. pinea's adaptability and provide practical approaches to its sustainable management. In this study, we reconstructed and compared the stem radial growth of seven stone pine stands, two in southern Spain and five in central–southern Chile, growing under different climatic conditions. We quantified the relationships between growth variability and climate variables (total rainfall, mean temperature, and SPEI drought index). Growth was positively correlated with autumn rainfall in plantations and with autumn–winter rainfall in natural stands. Growth was also enhanced by high autumn-to-spring rainfall in the driest Chilean plantation, whereas in the wettest and coolest plantation, such correlation was found in winter and summer. A negative impact of summer temperature was found only in one of the five Chilean plantations and in a Spanish site. The correlation between SPEI and tree-ring width indices showed different patterns between and within countries. Overall, exotic plantations showed lower sensitivity to climate variability than native stands. Therefore, stone pine plantations may be useful to assist in mitigating climate change. [ABSTRACT FROM AUTHOR]

Our dataset contains the scans of 278 paper prints of contacts from a photogrammetric flight of 1972, plus a diagram for the relative location of each of the photograms. The paper prints served three years later, i.e. in 1975, for studying the soils of an irrigated district. The entire flight covered about 705 km2, in the semiarid Central Ebro Basin, at the province of Huesca, Spain. The flight encompasses the 359 km2-irrigated district fed by the sections 2nd and 3rd of the first part of the Canal of Monegros, plus the westward conterminous non-irrigated lands until the border with the province of Zaragoza (Fig. 1). The Spanish Ministry of Agriculture throughout its now extinct branch Institute for Agrarian Reform and Development, i.e. IRYDA by its Spanish acronym, contracted a consulting company to produce a report [1] about the location of saline and non-saline soils of the district in 1975. The soil surveyors used the paper prints for preparing the report and marked some of the prints with color wax-pencil. Most of these marks locate the sampled sites but also appear geographical names, schematic highlights of some terrain features, and mentions to ongoing land levelling or similar works.

Downed woody debris is important for biodiversity, forest regeneration, and carbon, nutrient, and water cycling, and past studies have examined how the coarse fraction is affected by climate or harvesting. In a field study in Douglas-fir dominated forests, we expand existing knowledge by investigating the interacting effects of climate and harvesting on downed woody debris of all sizes. Across a 900-km long latitudinal gradient in British Columbia, we found that coarse woody debris (CWD, >7.5 cm diameter) in humid climates contained 700% greater carbon stocks, had 500% greater volume, and was more diverse than in arid climates. Pre- and post-harvest, small and fine woody debris comprised a higher proportion of total woody debris carbon stocks in arid than moist climates, especially after clearcutting and seed tree treatments. Harvesting generally decreased total CWD volume, but it was not depleted on any site. Harvesting substantially reduced the volume of large, highly decomposed CWD except at the two most arid sites, and losses of large CWD increased with increasing tree removal. These losses were accompanied by a pulse of fresh, small diameter CWD and SWD which are short-term organic nutrient sources but have less habitat value than larger pieces and contribute to fuel loads. Because CWD was less abundant in arid than humid mature forests, care must be taken on arid sites to avoid its depletion during harvesting, especially clearcutting, where future woody debris inputs will not occur for decades. [ABSTRACT FROM AUTHOR]

Three Cenchrus species (C. biflorus, C. ciliaris, and C. orientalis) were collected from different ecological regions in the Punjab and Khyber Pakhtoonkhwa during July to September 2020 to evaluate tolerance to multiple abiotic stresses (aridity, salinity, and cold). Growth and biomass production was the maximum in C. biflorus, C. ciliaris, and C. orientalis under aridity stress. Aerenchyma formation and vascular tissue increased significantly in roots under aridity. In C. ciliaris, aerenchyma formation was recorded under cold stress. Root vascular tissue was higher under normal conditions (26.7%) and aridity (30.4%) stress in C. ciliaris. Stem parenchyma (29.1%) and vascular tissues (35.5%) showed an increase in C. biflorus under aridity, while mechanical tissue (33.6%) increased significantly under salinity stress. In C. biflorus and C. ciliaris, extensive sclerification was recorded in the stelar region under aridity stress. The stem radius of C. orientalis was greatest under salinity (27.0%) and cold (29.1%) stress, while parenchyma tissue was smaller (12.1%) under cold stress. Leaf thickness generally increased under abiotic stresses, and the maximum (43.0%) thickness was recorded in C. biflorus under aridity stress. Cenchrus biflorus, C. ciliaris, and C. orientalis showed strong association among morphological and leaf anatomical traits under aridity stress. Cenchrus orientalis showed high sclerification outside the vascular bundles of the leaf sheath. In saline conditions, vascular bundles were sclerified and enlarged. In and outside the vascular bundles of leaf blades, extensive sclerification was observed under cold stress conditions. Modifications in structural and functional traits were critical for the ecological success of Cenchrus species for survival in multiple environmental stresses. [ABSTRACT FROM AUTHOR]

In this study, the aridity index (AI) based on gridded climate data was validated for defining aridity and classifying aridity zones in Iraq through comparison with the results obtained by the station-based aridity index. Gauge-based gridded climate data taken from Climatic Research Unit Timeseries (CRU TS) were used to determine the annual value of four aridity indices (Lang, De Martonne, Ernic and UNEP AI) over the period 1998-2011. The results showed that the aridity distribution maps derived using grid-based aridity indices were reasonably close to those found using station-based ones. The four aridity indices properly identified similar aridity (dryness) classifications in both the station-based and grid-based aridity maps. The area percentage of each aridity class predicted by grid-based AIs was also compared with that obtained by the station-based AIs. The results showed that the variances between the area percentages predicted by grid-based AIs and those estimated using station-based AIs are fairly slight. The Lang AI exhibited the least variance (0.4%) while the De Martonne AI had the biggest variance (-4.8%). Despite these minor variances, it is however possible to conclude that the grid-based aridity index classified the aridity zones of Iraq as properly as the station-based aridity index did. [ABSTRACT FROM AUTHOR]

This review presents a comprehensive examination of recent advancements in utilizing multi-date satellite data to analyze spatial and temporal variations in seasonal and inter-annual surface water dynamics within arid environments of Africa. Remote sensing offers continuous, precise, and long-term datasets for surface water research. Various sensors with differing spatial resolutions are discussed, with high-resolution multispectral sensors providing superior spatial resolution but at higher costs. Conversely, dualsensor approaches, incuding optical sensors (Sentinel-2 and Landsat), radar satellites (Sentinel-1 and RADARSAT) and UAVs were investigated. The review further examines the efficiency and applicability of traditional algorithms such as the modified normalized difference water index (MNDWI), normalized difference water index (NDWI), and automated water extraction index (AWEI) in detecting and delineating surface water resources. Additionally, machine learning (ML) algorithms, including support vector machines (SVM), Random Forest (RF), deep learning and emerging methodologies like recurrent tranformer networks, have been explored. Therefore, we recommend that future research endeavours focus on leveraging high-resolution satellite imagery and integrating physical models with deep learning techniques, artificial intelligence, and online big data processing platforms to improve surface water mapping capabilities. [ABSTRACT FROM AUTHOR]

Two formerly broadly distributed woody Atriplex species now occur as fragmented populations across a range of microhabitats in the San Joaquin Valley Desert, southern California. We hypothesized that A. lentiformis and A. polycarpa exhibit inter- and intra-specific differences in their leaf and stem structural and functional traits corresponding with differences in soil salinity and aridity. Water potential, xylem structure and function and leaf traits were compared between three populations of A. lentiformis and four populations of A. polycarpa. The two species significantly differed in their xylem traits, with A. lentiformis displaying lower xylem density, wider mean and maximum vessel diameters and higher hydraulic conductivity (K s). They also differed in their leaf traits, such that A. lentiformis had larger leaves with higher specific leaf area (SLA) than A. polycarpa. Significant intra-specific differences occurred among leaf traits (leaf area, SLA) in A. lentiformis populations. In contrast, populations varied in their stem xylem structural traits (mean vessel wall thickness, mean vessel diameter, maximum vessel length) among A. polycarpa populations. Many of these differences were associated with soil salinity in A. lentiformis , and with minimum seasonal water potential in A. polycarpa. Overall, both saltbush species showed high intra- and inter-specific trait variation. This could be a critical consideration in understanding the evolution of these native species and has important implications for their conservation and restoration. [ABSTRACT FROM AUTHOR]

Archeological evidence from loess sediments from Shangchen on the southeastern Chinese Loess Plateau indicates a suspension of hominin occupation around the time of the early mid‐Pleistocene climate transition, prompting a re‐assessment of climate‐vegetation‐hominin interactions. Loess deposits with in situ lithic records cover the period of hominin occupation and reveal four distinct climate‐vegetation periods (2.1–1.8, 1.8–1.26, 1.26–0.9, and 0.9–0.6 Ma). Major oscillations in climate superimposed upon an aridification trend and an expansion of C4 herbaceous vegetation from about 1.26 Ma may have driven early humans to move to more hospitable locations in the region. Comparison with the record at Nihewan indicates that large‐scale climate oscillations induced disparate hominin responses due to distinctive local environmental conditions. Plain Language Summary: A combination of several lines of evidence suggests that changes in climate and their impacts on the availability of food and shelter from around 1.26 million years ago may have driven the dispersal of early humans from the southeastern Chinese Loess Plateau to more hospitable environments elsewhere in the region. Key Points: Pleistocene temperature, rainfall, and C4 plants ratios are quantitatively reconstructed from the Shangchen loess deposits with artifactsHigh climate variability, C4 plants expansion and aridification suspended hominin occupation at Shangchen during the early mid‐Pleistocene climate transitionHominins responded differently to large‐scale climate oscillations depending on distinctive local environmental conditions [ABSTRACT FROM AUTHOR]

The scientific grasp of the distribution and dynamics of land use and land cover (LULC) changes in South America is still limited. This is especially true for the continent’s hyperarid, arid, semiarid, and dry subhumid zones, collectively known as drylands, which are under-represented ecosystems that are highly threatened by climate change and human activity. Maps of LULC in drylands are, thus, essential in order to investigate their vulnerability to both natural and anthropogenic impacts. This paper comprehensively reviewed existing mapping initiatives of South America’s drylands to discuss the main knowledge gaps, as well as central methodological trends and challenges, for advancing our understanding of LULC dynamics in these fragile ecosystems. Our review centered on five essential aspects of remote-sensing-based LULC mapping: scale, datasets, classification techniques, number of classes (legends), and validation protocols. The results indicated that the Landsat sensor dataset was the most frequently used, followed by AVHRR and MODIS, and no studies used recently available high-resolution satellite sensors. Machine learning algorithms emerged as a broadly employed methodology for land cover classification in South America. Still, such advancement in classification methods did not yet reflect in the upsurge of detailed mapping of dryland vegetation types and functional groups. Among the 23 mapping initiatives, the number of LULC classes in their respective legends varied from 6 to 39, with 1 to 14 classes representing drylands. Validation protocols included fieldwork and automatic processes with sampling strategies ranging from solely random to stratified approaches. Finally, we discussed the opportunities and challenges for advancing research on desertification, climate change, fire mapping, and the resilience of dryland populations. By and large, multi-level studies for dryland vegetation mapping are still lacking.

This article presents and reviews the soil salinity data provided by a rescued vintage agronomic report on an irrigated area of 35,875 ha located in the center of the Ebro River basin, in the NE of mainland Spain. These data come from a soil sampling campaign conducted from May to the first half of July 1975 for the purpose of delineating saline and non-saline soils. The agronomic report was produced in response to demands from farmers to combat soil salinity, and represents the state of the art in those years for salinity studies. Our paper presents the scrubbed soil salinity data for this year, checking their consistency and locating the study sites. The main finding is the unearthing of this heritage report and the discussion of its soil salinity data. We show that the report supplies an assessment and a baseline for further soil salinity tracking by conducting new measurements either by direct soil sampling or by nondestructive techniques, providing an estimate of soil salinity at different locations. This task is feasible, as shown in our previously published articles involving nearby areas. A comparison of the salt amount in the soil over the years would provide a means to evaluate irrigation methods for sustainable land management. This comparison can be conducted simultaneously with analysis of other agricultural features described in the report for the irrigation district in 1975. [ABSTRACT FROM AUTHOR]

• Based on the principles of SPEI, we develop a GDAI. • The relationship between GDAI and AI is closer. • The correlation between GDAI and SPEI is also better. Climate change has increased the risk of drought in both arid and non-arid regions of the globe. Therefore, in order to monitor and evaluate global drought and aridity, based on the principle of standardized precipitation evapotranspiration index (SPEI), this paper selected precipitation and potential evapotranspiration data and used a frequency calculation method to develop a multi-scale global drought aridity index (GDAI) that concurrently considers spatial and temporal variation characteristics: the spatiotemporal standardized precipitation evapotranspiration index. The index was compared with the aridity index (AI) and SPEI. The results showed that the correlation coefficients between GDAI and AI were greater than 0.8 in most areas, and the relationship was closer and could reveal the global aridity and wetness zoning. In addition, the correlation between GDAI and SPEI was also better, which could capture the temporal change characteristics of drought. Moreover, this study also compared the grades of GDAI and SPEI with the actual drought grades in Yunnan from September 2009 to August 2010, and found that GDAI was better than SPEI, and GDAI was the most accurately evaluated at the 3 month time scale, with an accuracy rate of 86.11%. Therefore, this index is more helpful for the assessment and monitoring of global drought and aridity. [ABSTRACT FROM AUTHOR]

The agroclimatic indicators for the territory of the Central Chernozem region are analyzed. The features of their spatial and temporal distribution are investigated. The tendencies of the indicators of thermal and moistening regimes are studied. An assumption is made about the future development of the agroclimatic potential on the territory of the Central Chernozem region. [ABSTRACT FROM AUTHOR]

This article analyzes a set of species of allergenic plants in the lowland biomes of Russia. Their species diversity was revealed, a statistical analysis of the relationships between the number of allergenic plant species in regional biomes and climatic indicators was carried out, and the corresponding maps were built and their analysis was given. It is shown that the distribution of the number of allergenic plant species in the spring reflects their clear predominance in broad-leaved forest and forest-steppe biomes, while in the summer allergenic plants predominate in forest-steppe and steppe biomes. The closest positive relationship has been established between the number of allergenic plant species that bloom in the summer and the average annual air temperature, as well as between all allergenic plant species and the average annual air temperature. However, the relationship between the number of allergenic plant species in the biome and the aridity index turned out to be low. [ABSTRACT FROM AUTHOR]

Local homogeneity, in ecology, is the often undisclosed assumption that variability within populations is negligible or mostly distributed evenly. In large areas, this can lead to the aggregation of different populations without regard for their unique needs and characteristics, such as drought sensitivity and functional trait distributions. Here, we discuss whether this assumption can be justified, and we hypothesize that discerning the source of variation between plasticity and adaptation could be a feasible approach to formulate an informed decision. We test this hypothesis on plants, resorting to a common garden experiment to determine the source of variation of several plant functional traits at a local scale (~60 km) of three wild species: Quercus ilex, Pistacia lentiscus, and Cistus salviifolius. Individuals of each species were sourced from three key sites chosen along a local aridity gradient. Our approach led to the rejection of the local homogeneity assumption for Q. ilex and C. salviifolius at this scale due to the adaptive divergence observed among neighboring populations. This case study provides evidence that addressing local homogeneity can highlight diverging populations in a relatively simple way. We conclude that gathering empirical evidence on intraspecific variability is a feasible approach that can provide researchers with solid bases to decide whether to adopt the local homogeneity assumption or not. [ABSTRACT FROM AUTHOR]

Cenchrus ciliaris L. is a perennial grass that can grow in a diverse range of habitats including challenging deserts. The purpose of the study was to investigate the impact of aridity on morpho-anatomical and physiological traits in C. ciliaris populations collected from arid and semi-arid areas of Punjab, Pakistan. The populations growing in extremely arid conditions displayed a range of structural and physiological adaptations. Under extremely dry conditions, root epidermal thickness (90.29 µm), cortical cell area (7677.78 µm2), and metaxylem cell area (11,884.79 µm2) increased while root pith cell area (2681.96 µm2) decreased in tolerant populations. The populations under extremely aridity maximized leaf lamina (184.21 µm) and midrib thickness (316.46 µm). Additionally, highly tolerant populations were characterized by the accumulation of organic osmolytes such as glycinebetaine (132.60 µmol g−1 FW) was increased in QN poulations, proline (118.01 µmol g−1 F.W) was maximum in DF populations, and total amino acids (69.90 mg g−1 FW) under extreme water deficit conditions. In arid conditions, abaxial stomatal density (2630.21 µm) and stomatal area (8 per mm2) were also reduced in DF populations to check water loss through transpiration. These findings suggest that various parameters are crucial for the survival of C. ciliaris in arid environments. The main strategies used by C. ciliaris was intensive sclerification, effective retention of ions, and osmotic adjustment through proline and glycinebetaine under arid conditions. [ABSTRACT FROM AUTHOR]

Climate change has increased the risk of drought in both arid and non-arid regions of the globe. Therefore, in order to monitor and evaluate global drought and aridity, based on the principle of standardized precipitation evapotranspiration index (SPEI), this paper selected precipitation and potential evapotranspiration data and used a frequency calculation method to develop a multi-scale global drought aridity index (GDAI) that concurrently considers spatial and temporal variation characteristics: the spatiotemporal standardized precipitation evapotranspiration index. The index was compared with the aridity index (AI) and SPEI. The results showed that the correlation coefficients between GDAI and AI were greater than 0.8 in most areas, and the relationship was closer and could reveal the global aridity and wetness zoning. In addition, the correlation between GDAI and SPEI was also better, which could capture the temporal change characteristics of drought. Moreover, this study also compared the grades of GDAI and SPEI with the actual drought grades in Yunnan from September 2009 to August 2010, and found that GDAI was better than SPEI, and GDAI was the most accurately evaluated at the 3 month time scale, with an accuracy rate of 86.11%. Therefore, this index is more helpful for the assessment and monitoring of global drought and aridity.

The article discusses research which analyzed prospects of floriculture in arid and semi-arid regions in India. The study examined the impact of climate change on the floriculture sector, as well as the aridity degree of dryness during Kharif season. It outlines constraints in floriculture production in India and proposes a cut and loose approach to flower production and commercial seed production in arid and semi arid regions.

The species belonging to the genus Pistacia possess ecological, economic, and medicinal value. They show a very high ecological plasticity. This research is a contribution to the study of the intraspecific diversity and variability of 10 populations of Pistacia lentiscus in different bioclimates. Nine locations in Algeria and one site in France have been selected in order to understand the strategies developed by this species under extreme conditions, including altitude and aridity, and to identify the adaptive processes that can be observed based on the morphological and ultrastructural features of the leaf. As a result of this research, we have collected a large quantity of important information on morphological and microphytodermal leaf variability for the ten studied populations. The statistical analyses showed a very important difference in the studied characteristics between these populations. It has been demonstrated that environmental factors also have a significant impact on the heterogeneity of most measured leaf features. Moreover, the observations with the scanning electron microscope (SEM) enabled us to highlight new characteristics of the studied species, such as the glandular trichomes on the leaflets and embedded stomata in the epidermis. These criteria could supplement the existing morphological characteristics used in the systematic classification of the Pistacia genus. Overall, the studied species have shown xeromorphy features, which give them the opportunity to be used in desertification mitigation programs, due to their ability to withstand conditions of extreme aridity. [ABSTRACT FROM AUTHOR]

We explored the influence of habitat structure on bird density and species richness in the poorly known bird communities in the steppes of Eastern Morocco, along a 200 km long N–S gradient of increasing aridity. The birds were surveyed, and habitat structure was measured in 44 transects regularly distributed along the gradient and during the winter and spring seasons in two consecutive years. After applying a principal component analysis (PCA), five axes were identified, including one related to the latitude–altitude–soil-type gradient and another describing the development of herbaceous vegetation. Generalized linear models were used to explore the relations between bird density and species richness with PCA axes in each season, considering both the entire community and groups of granivorous, insectivorous, and mixed-diet species. More than 90% of the birds were year-round residents, with larks dominating the community in both seasons. We conclude that a distinct multifactorial response can be identified for each functional group of species. In the winter, the community is mainly affected by the structure of the habitat, while aridity (and its assumed relation to primary production) is less influential. In the spring, habitat structure continues to have the greatest explanatory power, but location along the aridity gradient becomes more relevant. These findings reveal the interaction of the negative effects of climatic and anthropogenic changes in the habitat available to these bird communities, with a greater impact expected on birds with diets that include seeds, as well as a general shift of optimal breeding conditions toward more northerly latitudes. [ABSTRACT FROM AUTHOR]

Ecosystem responses to environmental change are usually studied solely using aboveground (usually leaf) traits. However, belowground plant traits, such as fine roots and coarse belowground organs, likely play a crucial role in ecosystem response, especially under aridifcation. We conducted a literature survey on belowground plant traits along aridity gradients in temperate grasslands to propose which effect traits might be connected with abrupt vegetation changes that would occur with aridification due to environmental change. With increasing aridity, seasonal regeneration decreasingly relies on recruitment from the belowground bud bank and increasingly relies on regeneration from seeds. This leads to greater inter-annual variability in biomass production. Other belowground traits, such as bud bearing organs and fine root distribution in the soil, also shifts along the aridity gradient. As aridifcation begins, we propose that plants would become more conservative in their belowground traits producing lower amounts of belowground litter. Increasing aridifcation would lead to the loss of rhizomatous plants from the community and a prevalence of deep rooting plants leading to changes in soil resource utilization and increasing susceptibility to soil erosion. Under extreme aridification, perennial plants, except those with bulbs, would be lost from the community and replaced by annuals which produce low amounts of litter and use only ephemeral water resources in the upper soil layers. Belowground plant traits, such as belowground clonal growth organs, bud banks, and fine root distributions, may provide a more mechanistic understanding behind shifts in ecosystem functioning due to environmental change. [ABSTRACT FROM AUTHOR]

Arid environments are suitable for researching the resilience of landscapes, since their ecological conditions pose continuous water stress to plants, animals, and humans living there. It is not only water, but also soil that is a limited resource. The arid landscape of the Eastern Marmarica (NW-Egypt) serves as an example for studying the resilience in and of a past landscape and its inhabitants from the 2nd millennium BCE to the 1st millennium CE, which is conceptualised as a 'social arid landscape'. The adapted life strategies and resilient practices to make a living in the arid environment are reconstructed from (geo-) archaeological evidence, discussing the applicability of the concept of resilience for ancient (landscape) studies. Resilience is an etic concept, depending on the perspective on and scale of a system. With the categories of 'event', 'practice' and 'knowledge', however, various scales can be bridged; life strategies can be defined as communities of practice and dichotomies be solved. Niche dwellings in the ancient Marmarica, where exposure to stress was normal, functioned because of an elaborate water management and the mobility of the people living there. The resilience of the arid social landscape is based on mixed life strategies, where only a multi-factored crisis (economic and climatic) or a series of smaller shocks (many dry years) could have destructive impacts. [ABSTRACT FROM AUTHOR]

Freshwater resources are uncertain in Palestine and their uncertainty is expected to intensify due to climate change and the political situation. Yet, in this region, a stable freshwater supply is vital for domestic and agricultural uses. Rainwater harvesting could help to increase freshwater availability. This study investigates the economic feasibility of two rainwater harvesting applications in the West Bank, with eyebrow terracing in olive groves in rural areas and domestic rooftop harvesting in urban areas. Cost-effectiveness is estimated using a spatially explicit cost–benefit analysis. Three land zones varying in suitability for the implementation of eyebrow terracing in olive groves are analyzed. The potential increase in olive yield is estimated with a crop–water balance model. The potential amount of rainfall that can be harvested with domestic rooftop harvesting is calculated based on the average rooftop area for each of the 11 governorates individually. Costs and benefits are considered at the household level to calculate the economic feasibility of these two applications. Although eyebrow terracing enlarges soil moisture availability for olive trees and thereby increases olive yield by about 10–14%, construction costs are too high to make implementation cost-effective. Similarly, rooftop harvesting can harvest about 30% on average of the annual domestic water demand and is worthwhile in the northern and southern governorates. Yet, in this case, construction costs are generally too high to be cost-effective. This obstructs more widespread adoption of rainwater harvesting in the West Bank, which is urgently needed given the large impacts of climate change. Providing subsidies for rainwater harvesting could help to make adoption more attractive for households. [ABSTRACT FROM AUTHOR]

The summer monsoon transition zone (SMTZ) in China represents an unusual land type with an agro-pasture ecotone, and it is a climate-sensitive region. Changes in climate aridity and changes in meteorological drought are mutually related yet fundamentally different. In this study, potential evapotranspiration (ETO) is calculated using Penman–Monteith, based on China's national meteorological stations data from 1961 to 2013. An ETO-based climate aridity index (IAI) and ETO-based standardized precipitation evapotranspiration index (SPEI) are used as the metrics for climate aridity and meteorological drought, respectively. The result shows a significant difference between climate aridity and meteorological drought in the SMTZ, compared with the monsoon and non-monsoon zone. This difference varies on different time scales (1–48 months), and the greatest differences between IAI and SPEI are on seasonal and monthly scales (1–12 months), but lower at longer time scales (>12 months). The first reason for the difference is the desynchronicity of meteorological drought and the background climate. After the background climate becomes a relatively arid state (such as 0.96 < IAI < 1) from a semi-arid state (0.50 < IAI < 0.80), the continued arid state with weak IAI fluctuations eventually results in increasingly severe meteorological droughts, or the recurrence of equally severe droughts with drastic reduction. Consequently, the onset of the most severe climate aridity is two to seven months (mostly three to four months) ahead of the onset of the most severe drought events, until the climate returns to a semi-arid state. Second, climate aridity represents the average state of the background climate over a long time period and changes gently, while meteorological droughts are stochastic climate events and change drastically. These findings indicate that IAI can serve as a predictor of the onset of meteorological drought events, especially in the SMTZ, but it fails to characterize the progression of meteorological drought events well. Therefore, this result is of great significance for drought prediction and early warning. [ABSTRACT FROM AUTHOR]

Spatial vegetation patterns are associated with ecosystem stability and multifunctionality in drylands. Changes in patch size distributions (PSDs) are generally driven by both environmental and biological factors. However, the relationships between these factors in driving PSDs are not fully understood. We investigated 80 vegetation plots along an aridity gradient in the Alxa plateau, Northwest China. The sizes of vegetation patches were obtained from aerial images, and the heights of patch‐forming species were measured in the field. Soil samples were collected on the bare ground between patches for determination of physiochemical properties. Point pattern analysis was used to infer plant–plant interactions. A model selection procedure was employed to select the best predictors for the shape of PSDs and biological factors (vegetation total cover, community plant height, and plant–plant interactions). We then used structural equation modeling to evaluate the direct and indirect effects of environmental and biological factors on the shape of PSDs. In our study area, two types of PSDs coexisted, namely those that best fit to power law distributions and those that best fit to lognormal distributions. Aridity was the main environmental factor, while community mean height and competition between plants were the main biological factors for the shape of PSDs. As aridity and community mean height increased, power law‐like PSDs were exhibited, whereas competition led to deviations of PSDs from power laws. Aridity affected the shape of PSDs indirectly through changes in community mean height. Community mean height was correlated with competition, thereby indirectly affecting the shape of PSDs. Our results suggest the use of community functional traits as a link between the environment and plant–plant interactions, which may improve the understanding of the underlying mechanisms of PSD dynamics. [ABSTRACT FROM AUTHOR]

Forest management depends on forest condition data and the ability to quantify the impacts of management activities to make informed decisions. Spatially quantifying water yield (WY) from forests across large landscapes enables managers to consider potential WY changes when designing forest management plans. Current forest water yield datasets are either spatially coarse or too restricted to specific sites with in situ monitoring to support some project-level forest management decisions. In this study, we spatially apply a stand-level southern pine WY model over a forested landscape in the Florida panhandle. We informed the WY model with pine leaf area index inputs created from lidar remote sensing and field data, a spatial and temporal aridity index from PRISM and MODIS data, and a custom depth to groundwater dataset. Baseline WY conditions for the study area were created using the Esri and Python tools we developed to automate the WY workflow. Several timber thinning scenarios were then used to quantify water yield increases from forest management activities. The results of this methodology are detailed (10 m spatial resolution) forest WY raster datasets that are currently being integrated with other spatial datasets to inform forest management decisions. [ABSTRACT FROM AUTHOR]

Tenebrionids represent a conspicuous component of the fauna of Mediterranean coastal dunes showing particular adaptations to the extreme climatic conditions of these environments (high temperature and aridity). These adaptations involve, for example, distinct morphological traits (such as long legs and subelytral cavity), finely tuned life cycles, ecological specialization, and diel and seasonal activity patterns that vary in response to temperature changes. Although these species are able to cope with high temperature and water scarcity, the ongoing climatic change may represent a serious threat. Increases in average temperatures and in frequency and severity of extreme events may affect profoundly species that already live close to their upper climatic tolerance limits. Tenebrionids in Mediterranean sand dunes are also flightless: although flightlessness is advantageous in this type of environment, it reduces substantially dispersal capabilities, and hence the possibility of tracking suitable climatic conditions. In fact, because of their adaptations to sand substrates and the limited extension of sandy shores, these animals are strictly confined to environments that are experiencing a dramatically fast increase in average temperature with no possibility to escape. [ABSTRACT FROM AUTHOR]

Climate models project that many terrestrial ecosystems will become drier over the course of this century, leading to a drastic increase in the global extent of arid soils. In order to decrease the effects of climate change on global food security, it is crucial to understand the arid environment and the constraints associated with arid soils. Although the effects of aridity on aboveground organisms have been studied extensively, our understanding of how it affects soil processes and nutrient cycling is lacking. One of the primary agricultural constraints, particularly in arid locations, is water scarcity, due to which arid soils are characterized by sparse vegetation cover, low soil organic carbon, poor soil structure, reduced soil biodiversity, and a high rate of soil erosion via wind. Increased aridity will limit the availability of essential plant nutrients and crop growth, and subsequently pose serious threats to key ecological processes and services. The increasing rate of soil salinization is another major environmental hazard that further limits the agricultural potential of arid soils. These soil constraints can be ameliorated and the crop yields increased through case-specific optimization of irrigation and drainage management, enhancing the native beneficial soil microbes, and combinations of soil amendments, conditioners, and residue management. This review explores technologies to ameliorate soil constraints and increase yields to maintain crop output in arid soils. [ABSTRACT FROM AUTHOR]

Groundwater is an invaluable global resource, but its long‐term viability as a resource for consumption, agriculture, and ecosystems depends on precipitation recharging aquifers. How much precipitation recharges groundwaters varies enormously across Earth's surface, yet recharge rates often remain uncertain. Here we use a global synthesis of field‐estimated recharge across six continents to show that globally recharge first‐order follows a simple function of climatic aridity. We use this relationship to estimate long‐term recharge in energy‐limited systems outside of permafrost regions. Our aridity‐based recharge estimates are consistent with the global field data but, on average, double previous estimates of global models. Our higher recharge estimates are likely caused by preferential groundwater recharge and discharge occurring at grid scales finer than global models. The higher recharge estimates suggest that more groundwater contributes to evapotranspiration and streamflow than previously represented by global hydrological models and global water cycle diagrams. Plain Language Summary: Groundwater is an essential resource for societies and ecosystems. The rate at which rainfall and snow replenish groundwater storage is important as it dictates the upper limit of sustainable groundwater use. Here we use measurements of groundwater recharge to show how climate determines groundwater recharge rates. Measured recharge rates, on average, strongly exceed those of models. This suggests there is more recharge globally than currently acknowledged. Consequently, also more groundwater recharge must get back to Earth's surface via river flow or water use of vegetation. Key Points: A global recharge data set indicates that climate strongly shapes the fraction of precipitation that will recharge groundwatersThis recharge data set indicates more recharge globally than existing global hydrological models suggestThus, more groundwater must contribute to evaporation and streamflow than represented by current global models and water cycle diagrams [ABSTRACT FROM AUTHOR]