Arid Zone Research Articles

Phylogenetic diversity drives soil multifunctionality in arid montane forest-grassland transition zone.

Exploring plant diversity and ecosystem functioning in different dimensions is crucial to preserve ecological balance and advance ecosystem conservation efforts. Ecosystem transition zones serve as vital connectors linking two distinct ecosystems, yet the impact of various aspects of plant diversity (including taxonomic, functional, and phylogenetic diversity) on soil multifunctionality in these zones remains to be clarified. This study focuses on the forest-grassland transition zone in the mountains on the northern slopes of the Tianshan Mountains, and investigates vegetation and soil characteristics from forest ecosystems to grassland ecosystems to characterize plant diversity and soil functioning, as well as the driving role of plant diversity in different dimensions. In the montane forest-grassland transition zone, urease (URE) and total nitrogen (TN) play a major role in regulating plant diversity by affecting the soil nutrient cycle. Phylogenetic diversity was found to be the strongest driver of soil multifunctionality, followed by functional diversity, while taxonomic diversity was the least important driver. Diverse species were shown to play an important role in maintaining soil multifunctionality in the transition zone, especially distantly related species with high phylogeny. The study of multidimensional plant diversity and soil multifunctionality in the montane forest-grassland transition zone can help to balance the relationship between these two elements, which is crucial in areas where the ecosystem overlaps, and the application of the findings can support sustainable development in these regions.

Evaluating Spatiotemporal Patterns and Integrated Driving Forces of Habitat Quality in the Northern Sand-Prevention Belt of China

Understanding habitat quality patterns and their drivers in arid zones is of fundamental importance to the sustainability maintenance of terrestrial ecosystems, but remains elusive. Here, we applied the InVEST model to investigate the spatiotemporal patterns of habitat quality in the northern sand-prevention belt (NSPB) across five time periods (2000, 2005, 2010, 2015, 2018), coupled with the structural equation model (SEM) and boosted regression tree (BRT) model to identify their integrated driving forces. The results exhibited that habitat quality in high-level zones expanded gradually from 2000 to 2018, while the middle- and low-level zones shrank. Climate, soil, topography, and human activities were significantly correlated with habitat quality, with mean annual temperature (MAT) and human activities being key contributing factors in the high-level and low-level zones, respectively, whereas the contribution of factors varied considerably in the middle-level zones. The interactions among climate, soil, topography, and human activities jointly drive habitat quality changes. Climate intensified the positive effects of soil on habitat quality, while the topographic and human activities mainly affected habitat quality indirectly through climate and soil. Our findings offer a scientific guidance for the restoration and sustainable management of desertification ecosystems in northern China.

Spatial and temporal groundwater dynamics in extreme arid basins

AbstractTo accurately obtain the spatial distribution characteristics of groundwater level in an extremely arid zone and its dynamic change patterns under the influence of human activities, based on the data of 55 groundwater observation wells in the middle and lower reaches of the Kriya River, spatial interpolation of regional groundwater level data were performed using the inverse distance weight, spline function, trend surface, and the ordinary kriging methods. The optimal interpolation method was selected by its accuracy to spatially interpolate the groundwater level data in the study area from 2019 to 2021. The results show that: (1) the ordinary kriging method has the highest interpolation accuracy (MAE = 7.1393, MRE = 0.0058, RMSE = 9.4314) and reflects the spatial and temporal variability and distribution characteristics of groundwater levels with great accuracy. (2)The relationship between surface water–groundwater recharge and discharge in different areas of the river channel in the desert section varies depending on geological structure, surface water seepage, and other elements. (3) Groundwater in the Taklamakan Desert has little effect on groundwater recharge in the Dariyabui Oasis, and changes in groundwater dynamics in the oasis are predominantly influenced by surface runoff. (4) Monthly changes in groundwater levels in the Yutian Oasis are continuous, with ‘V’ shaped fluctuations, a declining trend in the southern part, no significant change in the central part, and a slight increase in the northern part. These results contribute to the sustainable management of water resources in the Kriya River Basin, provide a basis for groundwater prediction, and offer a reference for studies of other, similar extreme desert area basins.

Heat stress conditions affect the social network structure of free-ranging sheep.

Extreme weather conditions, like heatwave events, are becoming more frequent with climate change. Animals often modify their behaviour to cope with environmental changes and extremes. During heat stress conditions, individuals change their spatial behaviour and increase the use of shaded areas to assist with thermoregulation. Here, we suggest that for social species, these behavioural changes and ambient conditions have the potential to influence an individual's position in its social network, and the social network structure as a whole. We investigated whether heat stress conditions (quantified through the temperature humidity index) and the resulting use of shaded areas, influence the social network structure and an individual's connectivity in it. We studied this in free-ranging sheep in the arid zone of Australia, GPS-tracking all 48 individuals in a flock. When heat stress conditions worsened, individuals spent more time in the shade and the network was more connected (higher density) and less structured (lower modularity). Furthermore, we then identified the behavioural change that drove the altered network structure and showed that an individual's shade use behaviour affected its social connectivity. Interestingly, individuals with intermediate shade use were most strongly connected (degree, strength, betweenness), indicating their importance for the connectivity of the social network during heat stress conditions. Heat stress conditions, which are predicted to increase in severity and frequency due to climate change, influence resource use within the ecological environment. Importantly, our study shows that these heat stress conditions also affect the animal's social environment through the changed social network structure. Ultimately, this could have further flow on effects for social foraging and individual health since social structure drives information and disease transmission.

Functional interactions between coat structure and colour in the determination of solar heat load on arid living kangaroos in summer: balancing crypsis and thermoregulation

Interactions of solar radiation with mammal fur are complex. Reflection of radiation in the visible spectrum provides colour that has various roles, including sexual display and crypsis, i.e., camouflage. Radiation that is absorbed by a fur coat is converted to heat, a proportion of which impacts on the skin. Not all absorption occurs at the coat surface, and some radiation penetrates the coat before being absorbed, particularly in lighter coats. In studies on this phenomenon in kangaroos, we found that two arid zone species with the thinnest coats had similar effective heat load, despite markedly different solar reflectances. These kangaroos were Red Kangaroos (Osphranter rufus) and Western Grey Kangaroos (Macropus fuliginosus).Here we examine the connections between heat flow patterns associated with solar radiation, and the physical structure of these coats. Also noted are the impacts of changing wind speed. The modulation of solar radiation and resultant heat flows in these coats were measured at wind speeds from 1 to 10 m s−1 by mounting them on a heat flux transducer/temperature-controlled plate apparatus in a wind tunnel. A lamp with a spectrum like solar radiation was used as a proxy for the sun. The integrated reflectance across the solar spectrum was higher in the red kangaroos (40 ± 2%) than in the grey kangaroos (28 ± 1%). Fur depth and insulation were not different between the two species, but differences occurred in fibre structure, notably in fibre length, fibre density and fibre shape. Patterns of heat flux within the species’ coats occurred despite no overall difference in effective solar heat load. We consider that an overarching need for crypsis, particularly for the more open desert-adapted red kangaroo, has led to the complex adaptations that retard the penetrance of solar radiation into its more reflective fur.

Microhabitat characterization in the home range of the Mule deer (Odocoileus hemionus) in arid zones

Knowing the home range of a species helps to identify the resources it needs to survive and reproduce and how this behavior is expressed spatially. Within home ranges, core areas are the sites where the main resources are abundant. The microhabitat is a spatial area composed of variables that can affect individual behavior. In this sense, the characterization of this inner part of the home range can contribute significantly to understanding the elements that these areas offer compared to the rest of the habitat of a population. This work characterized the home range and areas outside it, as well as the core areas of female mule deer on a microhabitat scale in the Chihuahuan Desert, México. The structure and composition of the vegetation were characterized according to three habitat use hierarchies: interior of the core areas and zones within and outside the home ranges of seven female mule deer. A Principal Component Analysis (PCA) was performed, and a hierarchical clustering was used to relate the variables. The variation in structure and composition in each hierarchy was evaluated by performing multivariate permutation tests. Twenty-five plant species were recorded in the transects. The PCA showed the most similar use hierarchies are the core and home range inner areas. The core area presents higher density and cover-dominance values, and the zone outside the home range showed high values of distance to the individual closest to the central point and greater variation in this parameter. The MANOVA indicated a significant variation in vegetation structure and composition in relation to use hierarchies. Significant differences in vegetation structure and composition were found at the microhabitat level between the core area of activity and the zones within and outside the home range. The core area has a greater structural complexity of vegetation, with greater plant coverage-abundance and density; this suggests that the core area is located in a more competitive and saturated environment. Outside the home range, the microhabitat has greater spatial heterogeneity of vegetation, with greater distance and variation of plant cover. Future research could address the spatial (micro-macro) and temporal scales to better understand the ecological dynamics of the species in different habitat use hierarchies.

Spatiotemporal Analysis of the Interactions between Ecosystem Services in Arid Areas and Their Responses to Urbanization and Various Driving Factors

In recent years, rapid urban expansion and increasing ecological sensitivity in arid zones have led to extreme imbalances in ecosystem development. Therefore, there is an urgent need to balance the dual goals of synergistic development of ecosystem services (ESs) and increased urbanization. Previous studies have analyzed the impacts of urbanization on ESs but have selected a limited number of indicators and have not focused on the impacts of urbanization on ES pair interactions. In this study, six key ESs (water yield, habitat quality, soil conservation, carbon storage, carbon sequestration and oxygen production, and food production) and total ecosystem services (TESs) were selected, and trends in the temporal and spatial relationship between trade-offs and synergies were analyzed over 20 years. This study refined the living standards urbanization indicator and evaluated the impact of urbanization and multiple drivers on ESs and ES pair interrelationships based on geo-detectors and segmented linear regression. The results show that there is heterogeneity in the overall and regional ES trade-offs and synergistic relationships, and water yield (WY)-related ES pairs generally exhibit synergistic relationships at the overall level. Spatially, however, the trade-off ratio exceeds the synergy ratio. Segmented linear regression results show that the relationship between all the urbanization indicators and TESs demonstrates an upward trend followed by a downward trend. Measures such as the increase in man-made oases in the early stages of urbanization did have some positive effects on TESs. However, as urbanization increased, these positive effects were quickly offset by the negative effects of overdevelopment and environmental degradation, leading to an overall decline in TESs. Urbanization of construction land (CL) had the most direct impact on ecosystem services. In summary, due to special climatic constraints, arid zones are more sensitive than other ecosystems, and urban development is strictly limited by oasis capacity. As cities expand, attention needs to be focused on protecting ecological land and limiting the expansion of CL to promote the synergistic development of urbanization and ecosystem services in arid zones.

Variation of the chemical and biochemical responses to salinity during germination and early growth of seedlings of two populations of Agave durangensis Gentry

Agave durangensis (Asparagaceae) sustains a mescal industry in Mexico. The main reproductive strategy of the species is by seeds. The increased demand for agave-based beverages encourages producers to seek new cultivation areas. However, more than half of the territory of the country includes arid and semiarid zones, which are highly affected by salinity. The aim of the current study was to determine if salinity triggers different seed germination potential and variable biochemical and chemical responses in seedlings of two populations of A. durangensis, that might confer different tolerance to salinity. Seeds from each population were irrigated with four salinity treatments. Germination potential, as well as growth parameters and biochemical and chemical attributes of seedlings, were determined. Although with reduced germinability and germination speed, seeds of the two populations were able to germinate even under the strongest NaCl concentration (100 mM) evaluated. Effects in the growth parameters were registered; however, the seedlings of both populations survived throughout the experiments, increasing chlorophyll content and cell viability in most saline treatments. The enzymatic defense mechanism and the accumulation of proline were activated in a salt-dependent manner, which did not occur with the phenolic compounds; however, monomeric anthocyanin accumulation was outstanding under the two strongest NaCl concentrations evaluated. Important interpopulation differences were registered in each type of response, which were differently regulated under variable NaCl concentrations, some of them being more important than others under a particular saline condition. Seeds from the population Durango were more sensitive to salinity.

An Evaluation of the Effects of the Herbal Supplements of Amla (Emblica officinalis) and Giloy (Tinospora cordifolia) on the Liver Function Parameters of Magra lambs Living in the Extensive System in Western Rajasthan's Arid Zone

The aim of this study was to determine the effect of herbal feed additives amla (Emblica officinalis) and giloy (Tinospora cordifolia) on Liver Function Test parameters of Magra lambs in the extensive management system. The experiment was performed on twenty eight magra lambs of three to four months of age under the extensive system, which were randomly distributed into four experimental groups of seven lambs in each group in a randomized block design (RBD). Herbal feed additive amla (Emblica officinalis) fruit powder with seed and giloy (Tinospora cordifolia) stem powder were supplemented at level of 1.5g/kg body weight with concentrate as oral/feed supplemented in T1 and T2 group, respectively except control group (C) and T3 in extensive management system. Group T3 were supplemented with the combination of amla (Emblica officinalis) fruit powder and giloy (Tinospora cordifolia) stem powder at the level of 0.75g/kg body weight with concentrate as oral/feed. At the end of experiment it appears that supplementation of herbal feed additives amla and giloy do not effect liver activity during the experimental period. Therefore, it can be concluded that the experiment was safe and did not cause any damage to the liver.

Effect of Herbal Additives Amla (Emblica officinalis) and Giloy (Tinospora cordifolia) on Carcass Traits of Magra Lambs in the Semi Intensive Management System under the Arid Zone of Western Rajasthan

Aim: It was the objective of this study to determine whether the highly nutritious herbal feed additives Amla (Emblica officinalis) and Giloy (Tinospora cordifolia) impacted carcass traits of Magra lambs in the semi intensive system of management.
 Study and Design: The experiment involved 28 lean lambs between the ages of three and four months under a semi intensive system, distributed at random into four experimental groups of seven lambs each, according to the randomized block design.
 Place and Duration of Study: The campus is located at 236 meters above mean sea level in the heart of the Thar Desert at 28° 18' 0" N (28.3° N) latitude, 73° 30' 0" E (73.5° E) longitude and 28° 18' 0" N (28.3° N) latitude. The duration of experimental study was thirteen weeks.
 Methodology: In a semi-intensive management system, groups T1 and T2 received an oral/feed supplement consisting of 1.5g/kg body weight of Amla (Emblica officinalis) fruit powder with seed and Giloy (Tinospora cordifolia) stem powder, respectively, along with concentrate, excluding the control group and T3. Group T3 group received an oral/feed supplement comprising a combination of Amla (Emblica officinalis) fruit powder and Giloy (Tinospora cordifolia) stem powder at a dosage of 0.75g/kg body weight, along with concentrate.
 Results: At the end of experiment, no significant changes were found in carcass traits except hot and cold carcass weight though; they were within normal range.
 Conclusion: At the end of experiment it appears that incorporation of 1.5g/kg body weight Giloy stem powder can be used as a part of the strategy as it is effective to alleviate stress in lambs in the semi-intensive system of arid zone of Rajasthan.

The Impact of Climate Change on Aeromedical Retrieval Services in Remote Northern Australia: Planning for a Hotter Future.

It is known that environmental heat is associated with increased morbidity manifesting as increasing demand on acute care health services including pre-hospital transport and emergency departments. These services play a vital role in emergency care, and in rural and remote locations, where resource capacity is limited, aeromedical and other retrieval services are a vital part of healthcare delivery. There is no research examining how heat impacts remote retrieval service delivery. The Northern Territory (NT) of Australia is characterised by very remote communities with limited acute healthcare capacities and is a region subject to regular extreme tropical heat. In this study, we examine the relationship between aeromedical retrievals and hot weather for all NT retrievals between February 2018 and December 2019. A regression analysis was performed on the number of retrievals by clinical reason for retrieval matched to the temperature on the day of retrieval. There was a statistically significant exposure response relationship with increasing retrievals of obstetric emergencies in hotter weather in the humid climate zone and surgical retrievals in the arid zone. Retrieval services appeared to be at capacity at all times of the year. Given that there are no obstetric services in remote communities and that obstetric emergencies are a higher triage category than other emergencies (i.e., more urgent), such an increase will impede overall retrieval service delivery in hot weather. Increasing surgical retrievals in the arid zone may reflect an increase in soft tissue infections occurring in overcrowded houses in the hotter months of the year. Given that retrieval services are at capacity throughout the year, any increase in demand caused by increasing environmental heat will have broad implications for service delivery as the climate warms. Planning for a hotter future must include building resilient communities by optimising local healthcare capacity and addressing housing and other socioeconomic inequities that amplify heat-related illness.

Mapping of groundwater availability in dry areas of rural and urban regions in India using IOT assisted deep learning classification model

Groundwater is a crucial resource for fulfilling the water requirements of India's rural and urban areas. The heterogeneous nature of geological, hydrological, and climatic factors results in substantial variability in the accessibility of groundwater across disparate regions. The present investigation centers on the cartography of groundwater accessibility in arid zones of rural and urban Indian areas using a Deep Learning Classification Model (DL-GWCM) supported by the Internet of Things (IoT). The introductory section underscores the importance of groundwater in India, where groundwater sources cater to around 80% of rural and 50% of urban water demands. The text highlights statistical data derived from surveys that indicate a notable decrease in groundwater levels. This underscores the pressing necessity for implementing effective monitoring and management strategies. The DL-GWCM is a proposed solution that aims to enhance the precision and effectiveness of groundwater availability mapping by incorporating IoT technology and Deep Learning Classification. The DL-GWCM comprises multiple constituent elements, such as Groundwater Prediction, Water Quality Index, and Conventional Neural Network- Bidirectional Long Short-Term Memory (CNN–Bi LSTM) classification. The process of Groundwater Prediction involves the utilization of past data and environmental factors to make precise forecasts of groundwater levels. The Water Quality Index evaluates the quality of subsurface water resources, guaranteeing their secure and enduring utilization. The Deep Learning Classification Model with IoT technology was implemented for groundwater accessibility mapping in Indian arid zones. It integrates Groundwater Prediction, Water Quality Index, and CNN–Bi LSTM classification. The model makes precise forecasts using past data and environmental factors, ensuring secure water quality. Using the CNN–Bi LSTM classification model improves the precision of groundwater availability mapping due to its resilient classification capabilities. These findings suggest that the DL-GWCM outperforms conventional approaches. The mean values of all five metrics for the proposed method are presented as follows: The performance metrics of the model are as follows: Root Mean Square Error (RMSE) of 0.77%, Mean Absolute Error (MAE) of 2.13%, Relative Absolute Error (RAE) of 8.72%, Root Relative Squared Error (RRSE) of 0.92%, and Correlation Coefficient (CC) of 0.92. The results of the proposed methodology facilitate the discernment of regions with abundant or scarce groundwater accessibility, thereby supporting the sustainable management and planning of groundwater resources.

A Growing Prosperity of Okra Cultivation (Abelmoschus esculentus L.) under Mahaneem (Ailanthus excelsa) Based Agro-Silviculture System in a Semi-Arid Region of India

Production of food to feed the rapidly growing population of India is the current challenge. To overcome such global issues of food security and climate change, there is a need to develop a good economically feasible agroforestry system in the tropics. Besides that, Indian farmers also facing the effect of climate change on the monocropping system and lack of optimum land utilization for their economic sustainability. Hence, the economic feasibility of okra cultivation in the agri-silviculture system of mahaneem (Alianthus excelsa) in the arid zone was conducted at the Regional Research Station in Bawal, Haryana, India during two consecutive rainy seasons from July 2020 to October 2020 and July 2021 to October 2021. To create an economically prosperous agro-forestry system, okra varieties Varsha Uphar and Hisar Naveen were planted under various planting densities of Mahaneem in an agri-silvicultural system. Nevertheless, agroforestry is a compelling alternative that encourages social, economic, ecological and agricultural sustainability in response to these challenges. The ratio of net return to cultivation cost was used to compute the benefit-cost ratio for the test of the economic feasibility of the proposed agroforestry system in the semi-arid zone climate of India. The present study revealed that 10 x 10 m planting spacing with the Hisar Naveen okra variety calculated the highest net return (108528 Rs./ha & 123884 Rs./ha in the consecutive years) and benefit-cost ratio (1.90 & 1.86 in the consecutive years) which was highest profitable for farmers to get economic and ecological security. Hence, it is recommended that the Mahaneem-based agro-silviculture system, specifically incorporating the Hisar Naveen variety, proves to be economically more feasible compared to sole cropping which offers practical guidance for farmers and policymakers seeking effective strategies to enhance agricultural productivity amidst evolving environmental conditions.

Agronanotechnology in the arid zones of northern Mexico: Research, challenges, and new trends

The agri-food systems in arid zones face challenges related to climate change, desertification, and soil contamination from agrochemicals' actions, among others. The agronanotechnology can generate alternatives to these problems, but it is necessary to monitor its development to have elements to apply policies that are oriented to the attention of these regions with a social perspective. This scientific paper aims to present provide a study of the situation of agronanotechnology in the arid zones of northern Mexico. Using bibliometric tools, the academic output in the field and map the public research agenda, focusing on providing the set of crops to which the local research is directed was analyzed. Furthermore, the literature associated with the risks to human health and the environment derived from some nanomaterials of agri-food interest and clarify the areas of opportunity and trends was reviewed. The results show a total of 224 research articles authored by 1029 scholars in 161 journals published from 2004 to 2022; that research on this topic reached its highest value in 2018 and then levels off at a value around of ~37%. The findings show a research agenda related to crops of economic interest for the export market like tequila, tomato, avocado, chili, watermelon. In México, agronanotechnology is an emerging field that deals with some crops of economic interest, but its development needs to be intertwined with the needs of rural producers.

Dynamics of Cotton Development in the Conditions of the Salyan Steppe of Azerbaijan

The arid climatic conditions of Azerbaijan belong to the arid zone, where the development of agriculture is entirely based on irrigation farming. Therefore, research on the irrigation of any agricultural plants cultivated in regions of Azerbaijan with different soil and climatic characteristics, and the application of their results in irrigated agriculture are of great importance. This article discusses the results of observations of the dynamics of cotton development, plant density, the weight of raw cotton in 1 boll and the biological productivity of the Logos variety of cotton. The geographical location of the Salyan Plain, geological and soil-climatic conditions of the area are described.

The V-shaped desert kites and their contribution to the Timnian economy

Desert kites are communal game traps that were used to harvest herds of ungulates, and there are more than 6000 in the arid zones of southwestern Asia. The oldest were dated to the 9th millennium cal B.C. and some were reused until the beginning of the 20th century. A wide range of types and dimensions is found throughout the region, but only the small V-shaped type is found in the cultural landscape of the Timnian, a Mid-Holocene culture in the southern Levantine deserts. The Timnian economy was based on nomadic pastoralism, rearing small herds of goats/sheep. In the southern Levantine deserts, pastoralism had to be augmented by other carbohydrate sources. It is apparent that the Timnians invested much effort and resources in kite construction to hunt ungulates; however, faunal assemblages from habitation camps, burial fields and ceremonial complexes show very few bones of hunted game. Here we test two competing hypotheses: the use of kites to augment food supply, versus the use of kites for social or ceremonial purposes. We review the Timnian culture, the local kites, and cost-benefits considerations, as well as issues regarding desert pastoralism. We conclude that the kites were mostly used in social and ceremonial contexts.

How will drought evolve in global arid zones under different future emission scenarios?

Study regionGlobal aridity zones. Study focusEvaluating drought under the impact of climate change is crucial for ensuring sustainable development and ecological security, especially in global arid zones where the environment is vulnerable to global warming. However, there are large uncertainties in evaluating the future drought risk of arid zones due to uncertainties within climate projections and the use drought-related indices that may not be appropriate for all assessments. Therefore, under the precondition of bias correction applied to CMIP6 data, the drought detection capability of drought indices calculated from multimodel ensemble was evaluated. Based on the drought index with the strongest detection capability and the Reliability-Resilience-Vulnerability (RRV) framework, the future drought risk in global arid zones were predicted. New hydrological insights for the regionAmong the drought indices calculated from CMIP6 historical simulations, SPEI offered the best representation of drought patterns. According to the CMIP6 future projections, SSP1–2.6 can effectively mitigate the impact of future drought risk compared with the historical period. In scenarios with higher emissions, the equatorial to northern latitude 30° region will experience more severe drought. For SSP5–8.5, the areas in the arid zones where drought risk deteriorates significantly are several times larger than in other scenarios. To mitigate drought risks, most nations should support a greener, low-emission approach in line with sustainable development goals, reducing the risk of drought-related damage.

Spatiotemporal evolution of agricultural drought and its attribution under different climate zones and vegetation types in the Yellow River Basin of China

Ecological protection and high-quality development of the Yellow River Basin (YRB) are major national strategies in China. Agricultural drought (AD) is one of the most important stress factors of the ecological security of the YRB. Currently, there is a lack of exploration of the spatiotemporal evolution of AD in the YRB under different climatic zones and vegetation types, and the mechanisms by the driving factors influence AD remain unclear. The Temperature Vegetation Dryness Index (TVDI) for the YRB in China during 2000–2020 was calculated using Land Surface Temperature (LST) and the Normalized Difference Vegetation Index (NDVI). We analyzed the spatiotemporal evolution of AD from the perspective of upstream of the YRB (UYRB), midstream of the YRB (MYRB), and downstream of the YRB (DYRB), as well as different climate zones and vegetation types. The driving factors were selected based on the Pearson correlation analysis, Geographical detector, and Mantel test. Structural equation modeling (SEM) was employed to quantify the direct and indirect effects of the driving factors on AD in the YRB. We found a slowing trend of AD in the YRB, mainly in the Loess Plateau, which is distributed in UYRB and MYRB, but an increasing trend for AD in DYRB. Temperature, which is the most direct influential factor, has exacerbated AD in UYRB and MYRB. However, surface solar radiation (SSR) has the greatest constraining effect on DYRB. AD increased in arid and desert zones, while a decreasing trend is observed for other climatic zones and vegetation types. In arid and semiarid zones, human activities and SSR were the largest indirect factors exacerbating AD. In humid and subhumid zones, the largest indirect factor exacerbating AD was potential evapotranspiration (PET). Temperature is the most direct factor exacerbating AD in cropland and forest, while PET is the largest indirect factor exacerbating AD in grassland. This study elucidates the driving factors and mechanisms of AD in the YRB to provide scientific decision support for mitigating regional drought and promoting regional sustainable development.

Seed priming with selenium improves growth and yield of quinoa plants suffering drought

Drought stress is a worldwide threat to the productivity of crops, especially in arid and semi-arid zones of the world. In the present study, the effect of selenium (Se) seed priming on the yield of quinoa under normal and drought conditions was investigated. A pot trial was executed to enhance the drought tolerance in quinoa by Se seed priming (0, 3, 6, and 9 mg Se L−1). The plants were exposed to water stress at three different growth stages of quinoa, viz. multiple leaf, flowering, and seed filling. It was noticed that drought significantly affected the yield components of quinoa, however, Se priming improved the drought tolerance potential and yield of quinoa by maintaining the plant water status. Se priming significantly increased main panicle length (20.29%), main panicle weight (26.43%), and thousand grain weight (15.41%) as well as the gas exchange parameters (transpiration rate (29.74%), stomatal conductance (35.29%), and photosynthetic rate (28.79%), total phenolics (29.36%), leaf chlorophyll contents (35.97%), water relations (leaf relative water contents (14.55%), osmotic potential (10.32%), water potential (38.35%), and turgor potential (31.37%), and economic yield (35.99%) under drought stress. Moreover, Se priming markedly improved grain quality parameters i.e., phosphorus, potassium, and protein contents by 21.28%, 18.92%, and 15.04%, respectively. The principal component analysis connected the various study scales and showed the ability of physio-biochemical factors to describe yield fluctuations in response to Se seed priming under drought conditions. In conclusion, a drought at the seed-filling stage has a far more deleterious impact among other critical growth stages and seed priming with Se (6 mg L−1) was found more effective in alleviating the detrimental effects of drought on the grain yield of quinoa.

Seasonally extreme temperature events accelerate in arid northwestern China during 1979–2018

The arid northwestern China is the most vulnerable region to climate change, where the variability of seasonally extreme temperature events has profound implications for both its hydrological, ecological, and human systems. In this study, we applied 15 indicators of extreme temperature to analyze the spatial and temporal variation of its occurrence in arid northwestern China for a recent 40-year period (1979 to 2018). These extreme temperature event dynamics were then combined with atmospheric and oceanic circulation to explore their response mechanisms. Our results revealed the following: (1) Over the 40-year period, the annual average temperature in this arid zone increased at a rate of 0.4 °C/decade (p = 0.09), exceeding the national average rate (0.28 °C/decade). Apart from a few indicators, extreme temperature events (TXx, TNx, TXn and TNn) generally increased at least twice as fast as average temperature during the four seasons, especially in spring, when TNn (0.98 °C/decade) rose five times faster than did the average temperature (0.2 °C/decade). (2) Spatially, except for the Kunlun Mountains and Tarim Basin, seasonal warming occurred in most parts of the studied arid zone, being most prominent in the summer. In this season, the average number of warm nights increased (3.23 days/decade), while the average number of cold nights decreased (2.69 days/decade). (3) After the 1990s, extreme temperature events accelerated significantly. The Cold Spell Duration Indicator decreased 42% in spring and the Warm Spell Duration Indicator increased 300% in summer, from 1979 –1998 to 1999–2018, which may hasten the formation of snow and glacier melt flooding events in the spring and summer. Spatiotemporal variability in seasonally extreme temperature events was closely related to atmospheric and oceanic circulation, particularly for the AMO (r = 0.8). Altogether, these findings enhance our understanding of how to better assess shifts in extreme temperature events in response to a changing climate in arid zones.