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This study highlights drought forecasting for understanding the semi-arid area in India, where drought phenomena play vital role in the irrigation, drinking water supplies, and sustaining the ecological with economic balance for every nation. Therefore, drought forecasting is important for the future drought planning based on the machine learning (ML) models. Hence, The Standardized Precipitation Index (SPI) at 3- and 6-month periods have been selected and used for future drought forecasting scenarios in area. The combinations of ten inputs SPI-1- and SPI-10 were used for predicting modeling for SPI-3 and SPI-6 timescales, that modeling developed based on the historical SPI datasets from 1989 to 2019 years. The SPI-3 and SPI-6 maximum and minimum values are shown SPI-3 (2.03 and -5.522) and SPI-6 (1.94 and -6.93). The SPI is a popular method for estimating the drought analysis and has been used everywhere at global level. The developed models have been compared with each other, with the best combination of input variables selected using subset regression models and sensitivity studies. After that, the active input parameters were used for forecasting of SPI-3 and SPI-6 values to understanding of drought in semi-arid area. The finest input variables combination have been used in the Ml models and established the novel five models such as robust linear regression, bagged trees, boosted trees, support vector regression (SVM-Linear), and Matern Gaussian Process Regression (Matern GPR) models. Such kind of models first time has been applied for the forecasting of future drought conditions. Whole models were fine and improved modeling by using hyperparameters tuning, bagging, and boosting models. Entire ML models' accuracy was compared using different statistical metrics. Compared with five ML models accuracy, we have found that the Matern GPR model better accuracy than other ML models. The best model accuracy is R2 = 0.95 and 0.93, RMSE, MSE, MAE, MARE, and NSE values, respectively, for predicting SPI-3 and SPI-6 values in the area. Therefore, the Matern GPR model was identified as the finest ML algorithm for predicting SPI-3 and SPI-6 associated with other algorithms. This research demonstrates the Matern GPR model's efficacy in predicting multiscale SPI-3 and SPI-6 under climate variations. It can be helpful in soil and water resource conservation planning and management and understanding droughts in the entire basin areas of the country India. [ABSTRACT FROM AUTHOR]

Climate change is leading to global increases in extreme events, such as drought, that threaten the persistence of freshwater biodiversity. Identification and management of drought refuges, areas that promote resistance and resilience to drought, will be critical for preserving and recovering aquatic biodiversity in the face of climate change and increasing human water use. Although several reviews have addressed the effects of droughts and highlighted the role of refuges, a need remains on how to identify functional refuges that can be used in a drought management framework to support fish assemblages. We synthesize literature on drought refuges and propose a framework to identify and manage functional refuges that incorporate species physiological tolerances, behaviours and life‐history strategies. Stream pools, perennial reaches and off‐channel habitat were identified as important drought refuges for fish. The ability of refuges to improve species resistance and resilience to drought requires careful consideration of the biology of the target species and targeted management to promote persistence, quality and connectivity of refuges. Case studies illustrate that management of drought refuges can be challenging because of competing demands for water, incomplete knowledge of ecological requirements for target species and the increasing occurrence of multi‐year droughts. Climate adaptation is increasingly important, and drought refuges can increase fish resistance and resilience to climate‐related drought across the riverscape. [ABSTRACT FROM AUTHOR]

The prevalence of drought events worldwide emphasizes the importance of screening and cultivating drought-adapted crops. In this study, 206 germplasm resources were used as materials, dry weight as target trait, and two genotyping methods as criteria to evaluate drought adaptability at the seedling establishment stage. The results showed a significant decrease in average dry weight of the tested germplasm resources (from 746.90 mg to 285.40 mg) and rich variation in the responses of dry weight among each genotype to drought (CV=61.14%). In traditional evaluation method, drought resistance coefficient (DC), geometric mean productivity index (GMP), mean productivity index (MP), stress susceptibility index (SSI), stress tolerance index (STI), and tolerance index (TOL) also exhibited diversity in tested genotypes (CV>30%). However, these indices showed varying degrees of explanation for dry weight under stress and nonstress environments and failed to differentiate drought adaptability among genotypes clearly. In new evaluation method, four stress indices were developed to quantify barley seedling production and stability capacities. Compared to traditional stress indices, the stress production index (SI) explained dry weight more comprehensively under stress conditions (R² = 0.98), while the ideal production index (II) explained dry weight better under non-stress conditions (R² = 0.89). Furthermore, the potential index (PI) and elasticity index (EI) eliminated disparities in traditional stress indices and comprehensively clarified the contribution of elasticity and potential to production capacity under drought stress. Ultimately, through grading evaluation and cluster analysis, the tested germplasm resources were effectively categorized, and 11 genotypes were identified as suitable for cultivation in arid areas. Overall, the comprehensive evaluation method based on the newly developed stress indices surpasses the traditional method in screening drought adaptability of crops and serves as a vital tool for identifying high-stability and high-production capacities genotypes in various environments, which is expected to provide practical guidance for barley planting and breeding in arid areas. [ABSTRACT FROM AUTHOR]

Drought is a major global challenge causing significant socio-economic and environmental impacts. A paradigm shift from crisis to risk management is advocated to reduce the impacts of droughts, and to build the resilience of societies, and water and environmental systems against drought. A number of drought policy and planning guidelines are developed and used to support the transition from crisis to risk management and enhancing resilience. However, research is lacking on critical reflection, evaluation and update of the available drought guidelines. For example, there is no study on assessing the correspondence of the available guidelines to the contemporary disaster risk reduction agenda. Therefore, this study evaluates twelve drought policy and planning guidelines for their alignment with the four priority areas of the SENDAI framework for disaster risk reduction 2015–2030. A qualitative evaluation matrix was developed and used in the assessment. The examined priorities and associated thematic elements were scored in the range 0–100, and classified under Very Low (0–10), Low (11–30), Medium-Low (31–50), Medium-High (51–70), High (71–90), and Very High (91–100) categories. Most guidelines achieved (medium) high to very high scores on data and information, risk assessment, and communication and dissemination elements associated with priority 1 (understanding disaster risk). Whereas, mostly very low to low coverage was found for science-policy-practice dialogue, local knowledge and practices, and research and development. Strengthening disaster risk governance to manage disaster risk (priority 2) earned high scores on most elements, notably for strategies and plans, coordination mechanisms, community representation, and policy and governance. In contrast, most elements under priority 3 (investing in disaster risk reduction) were classified under low to medium categories, which include financial allocation, risk transfer, and mainstreaming drought risk reduction into land use and rural development planning, business resilience and protection of livelihoods, and health and safety. Most elements under priority 4 (enhancing disaster preparedness) scored under medium low to medium high ranges, as sufficient information was lacking on multi-hazard early warning systems, post-disaster recovery, rehabilitation, and reconstruction, and resilience of critical infrastructure. Furthermore, the study outlined several strengths, weaknesses, opportunities and threats pertaining to the examined guidelines. In general, the study reveals an urgent need to better align drought policy and planning guidelines with the contemporary disaster risk reduction agenda outlined in the SENDAI Framework. The findings of this study can be instructive in designing the next generation of drought guidelines in support of an accelerated transition towards drought risk management, and building resilient societies and ecosystems under a changing climate and increasing anthropogenic pressures. [ABSTRACT FROM AUTHOR]

This study examines the spatiotemporal variability of drought and associated physical processes over the Arabian Peninsula (AP). For this purpose, we computed the standardized precipitation evapotranspiration index (SPEI) for the period 1951–2020 using the Climate Research Unit and fifth generation ECMWF atmospheric reanalysis datasets. By applying rotated empirical orthogonal function analysis on the SPEI data, we identified four homogeneous and coherent drought regions. The droughts in the northern regions follow a relatively similar temporal evolution as compared to those in the southern region. All four sub-regions of the AP exhibit a significant drying trend (p < 0.01) with an abrupt acceleration in drought frequency and intensity over the last two decades. The increase in droughts is associated with the reduction of synoptic activity and an increase in the high pressure over the AP. Seasonally, potential evapotranspiration is the dominant driver of summer droughts in the AP, whereas both precipitation and temperature are important for driving winter droughts. The summer droughts, mainly over the northern AP, are due to the occurrence of an anomalous equivalent barotropic high associated with anomalous dry and hot conditions. However, anomalous dry conditions in winter are a result of an anomalous paucity of winter storms caused by the weakening of the sub-tropical jets. [ABSTRACT FROM AUTHOR]

ABSTRACT Drought poses significant challenges to agricultural production, ecological stability and global food security. While wild pear trees exhibit strong drought resistance, cultivated varieties show weaker drought tolerance. This study aims to elucidate the molecular mechanisms underlying pear trees' response to drought stress. We identified a drought resistance‐related transcription factor, PbbZIP88, which binds to and activates the expression of the drought‐responsive gene PbATL18. Overexpression of PbbZIP88 in Arabidopsis and pear seedlings resulted in enhanced drought resistance and significantly improved physiological parameters under drought stress. We discovered that PbbZIP88 interacts with the key protein PbSRK2E in the ABA signalling pathway. This interaction enhances PbbZIP88's ability to activate PbATL18 expression, leading to higher levels of PbATL18. Furthermore, the PbbZIP88 and PbSRK2E interaction accelerates the regulation of stomatal closure under ABA treatment conditions, reducing water loss more effectively. Experimental evidence showed that silencing PbbZIP88 and PbSRK2E genes significantly decreased drought resistance in pear seedlings. In conclusion, this study reveals the synergistic role of PbbZIP88 and PbSRK2E in enhancing drought resistance in pear trees, particularly in the upregulation of PbATL18 expression, and the accelerated promotion of stomatal closure. These findings provide new candidate genes for breeding drought‐resistant varieties and offer a theoretical foundation and technical support for achieving sustainable agriculture. [ABSTRACT FROM AUTHOR]

An exponential rise in the atmospheric vapour pressure deficit (VPD) is among the most consequential impacts of climate change in terrestrial ecosystems. Rising VPD has negative and cascading effects on nearly all aspects of plant function including photosynthesis, water status, growth and survival. These responses are exacerbated by land–atmosphere interactions that couple VPD to soil water and govern the evolution of drought, affecting a range of ecosystem services including carbon uptake, biodiversity, the provisioning of water resources and crop yields. However, despite the global nature of this phenomenon, research on how to incorporate these impacts into resilient management regimes is largely in its infancy, due in part to the entanglement of VPD trends with those of other co‐evolving climate drivers. Here, we review the mechanistic bases of VPD impacts at a range of spatial scales, paying particular attention to the independent and interactive influence of VPD in the context of other environmental changes. We then evaluate the consequences of these impacts within key management contexts, including water resources, croplands, wildfire risk mitigation and management of natural grasslands and forests. We conclude with recommendations describing how management regimes could be altered to mitigate the otherwise highly deleterious consequences of rising VPD. Summary statement: Rising atmospheric vapour pressure deficit (or VPD) is one of the most widespread and significant consequences of climate warming for terrestrial ecosystems. This article reviews the mechanistic bases of these usually deleterious impacts and synthesises that information into a set of management recommendations to mitigate them. [ABSTRACT FROM AUTHOR]

Indicators are important tools for tracking the socio‐environmental impacts of droughts and building resilience to climate change. We begin with an overview of metrics used for water planning and drought management, with particular emphasis on the UK. We explain how considerations of cost, immediacy, access, consistency, relevance, reliability and others denote the suitability of information for developing new indicators. We then demonstrate the potential of Google Trends (GT) online search data as drought indicators for England and Ireland. We show that search terms such as 'drought', 'water butt' and 'hosepipe ban' correlate significantly with conventional hydroclimatic data as well as with newspaper reports of various drought impacts during the period 2011–2022. GT data also show evidence of rising interest in water saving technologies, especially for outdoor water use. Meanwhile, online searches for 'Defra' and 'Environment Agency' have declined and are more often associated with flood episodes than droughts. Interest in water companies in England is more likely around hosepipe bans than water leakage (although this varies by company). We discuss the implications of these findings for targeting information campaigns, plus prospects for monitoring drought impacts and public sentiment in near real‐time. [ABSTRACT FROM AUTHOR]

Drought poses a serious threat to the productivity of hop, an important perennial crop. However, the precise physiological mechanisms that make it highly susceptible to drought are not yet fully understood. In this study, we investigated stomatal regulation and xylem vulnerability to embolism, which are important traits closely associated with plant drought resistance. In a glasshouse cultivation experiment, we monitored changes in leaf water potential, stem elongation rates, and leaf gas exchange, including net photosynthetic rates, stomatal conductance, and intrinsic water use efficiency, on relatively young hop plants (traditional Saaz - Osvald's clone 31) exposed to declining soil water availability. The transpiration rate and stem elongation of plants decreased significantly with a small decline in substrate water potential (ΨSUB), indicating a highly sensitive stomata response during early phases of soil dehydration. The stem elongation was completely halted, and the transpiration rate dropped to less than 50% of its maximum at ΨSUB levels below − 0.8 MPa. In well-watered hop plants, xylem in stems operates near the initial point of embolization and is highly vulnerable to embolism, with a water potential corresponding to a 50% loss of xylem conductivity at -1.6 MPa. The sensitive stomatal response to declining ΨSUB likely helps to mitigate the risk of hydraulic failure, albeit at the cost of impaired growth. Scheduled irrigation, particularly during the sensitive stem elongation stage, may be a promising approach to mitigate the detrimental effects of reduced soil water availability on hop growth and yield while also conserving water resources. [ABSTRACT FROM AUTHOR]

• Identified the severity and frequency of drought in Singbhum Protocontinent, India. • Meteorological and remote sensing indices are used to identify drought dynamics. • 1.67 to 1.05 percent extreme drought frequency shows in the western part. • Poor aquifer properties and extreme climate are the main reason for droughts. • Sustainable watershed management is highly required. Drought is an extremely hazardous situation that predominantly affects ecosystems, hydrological systems, and agricultural mechanisms in different pockets of the world. Management of water resources in dry and semi-arid environments has become a critical challenge in the last few decades. The principal objectives of this study are (i) to categorize the severity and frequency of drought events using the Reconnaissance Drought Index and Rainfall Deviation Index and ii) to evaluate the spatial extension of drought in particular drought times of severe and extreme droughts through Remote Sensing Drought Indices (RSDIs). This drought monitoring index is commonly used index for its high degree of resilience and sensitivity to droughts. The result shows that severe to extreme drought occurred in Bero, Tulin, Sirkabad, Manbazar and Bundwan which are 22, 28, 23, 14 and 25 months correspondingly based on RDI3 whereas RDI12 values indicated 26, 47, 42, 22 and 38 months in the study period (1981 to 2021). Bundwan area faced the most extreme drought occurrence in May month of 1996 with −3.58 values followed by Sirkabad, Bero, Manbazar and Tulin. Manbazar is going through severe to extreme drought months (for short time) whereas 'extreme drought' frequency (1.67 % to 1.05 %) is higher in the western part mainly in Jhalda I, Jhalda II, Bagmundi, and Arsha blocks of Purulia district (part of Manbhum Singhbhum Plateau). Additionally, the recurrence of 'moderate drought' is much greater in Balarampur along with some portions of Purulia I block. The whole study can be summarized as the northeastern portion being challenged with moderate or severe drought conditions while mild or severe drought is a considerable recurrence in the northern section. The outcome of this study will be helpful for local planners and management officials during implementation strategies related to water resource management. [ABSTRACT FROM AUTHOR]

Background: As fire regimes continue to evolve in response to climate change, understanding how fire characteristics have responded to changes in the recent past is vital to inform predictions of future fire events. Aims and methods: Using Fourier Transform Infrared (FTIR) spectroscopy, we assessed how fire intensity has changed in two fire-prone landscapes in south-eastern Australia: (1) the Blue Mountains; and (2) Namadgi National Park during the past 3000 years. Key results: Higher aromatic/aliphatic ratios suggest increased high-intensity fire frequency in sediments at the surface of both cores. Increases in the frequency of extreme drought periods, coupled with the change in vegetation and anthropogenic ignitions following colonisation, could have increased the frequency of high-intensity fires in the past ~200 years. Conclusions: FTIR spectroscopy can be used in sediment deposits to infer that the frequency of high-intensity fire events has increased in the past 200 years compared to the previous ~3000 years. Implications: These results are important for understanding how past fire regimes have responded to climate, people and vegetation shifts in the past ~3000 years and can be used to inform models for future predictions and management strategies. Fourier Transform Infrared (FTIR) spectroscopy was applied to sediment deposits in southeastern Australia. The aromatic/aliphatic ratio was used as a proxy for high-intensity fires. The increased frequency of high-intensity fire events could result from interactions between climate, people, and vegetation. The existing fire record was extended by centuries to millennia. [ABSTRACT FROM AUTHOR]

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Water deficiency has become a serious ecological problem facing all mankind, and drought has become a key factor constraining the development of agricultural production. Gaining insights into drought response mechanisms is vital for crop adaptation. We present, here, a multifactorial study from germination to vegetative drought stages in the model plant Brachypodium hybridum. A total of 200 genotypes representing 10 natural populations (Fayedh, Enfidha, Jbel Zaghouan, Haouaria, Raouad, Sejnen, Ain Drahem, El Kef, Daouar El Hej Wniss and Djerba) which represent almost all the bioclimatic regions in Tunisia were used. High variation in germination capacity under drought stress was found between studied populations. It reaches 100% at 250 mV for Djerba population and decrease up to 40% at 100 mV. Drought caused significant increase in oxidative stress. Interestingly, genotype 8/14 originated from El Kef exhibited the highest leaf H2O2 content, resulting in higher leaf MDA accumulation. Consistently, no significant changes were observed in-SOD, CAT and GPX activities in both leaves and roots, relatively to unstressed state. Different profile was recorded in 6/9 originated from Raoued in which the most pronounced levels of H2O2 and MDA were observed in drought stressed roots. Concurrently, root CAT activity increased by 22-fold relatively to unstressed plants. Drought stress resulted in a decrease in H2O2 content, mitigation of lipid peroxidation in both leaves and roots of 6/5 genotype originated from Raoued, with a simultaneous increase in leaf and root SOD activity. This was associated with enhanced GPX activity where 75 and 40% of increase were recorded in genotype 6/5 in leaves and roots. [ABSTRACT FROM AUTHOR]

The Journal of Experimental Botany has published guidelines for designing and interpreting drought experiments in controlled conditions. The guidelines aim to address flaws in research on drought tolerance and plant responses to water deficit, such as flawed experimental designs and inconsistent terminology. The recommendations include using precise terminology, accounting for genotype-environment interactions, considering whole-plant transpiration, and measuring soil and plant water status. The article discusses the challenges and pitfalls of designing and conducting plant stress experiments, specifically focusing on drought and heat stress. The authors emphasize the importance of considering factors such as spatial and temporal variations, feedback mechanisms, and the pot effect in experimental design. They recommend researchers to recognize and report the limitations of their experiments, assess complex environmental interactions, and account for genotype-by-environment interactions when interpreting data. The article also highlights the need for accurate measurement of plant stress levels and the selection of appropriate variables and time points for measurement. The authors aim to provide guidance for researchers in designing rigorous and reproducible stress experiments. [Extracted from the article]

Drought is deemed a major natural disaster that can lead to severe economic and social implications. Drought indices are utilized worldwide for drought management and monitoring. However, as a result of the inherent complexity of drought phenomena and hydroclimatic condition differences, no universal drought index is available for effectively monitoring drought across the world. Therefore, this study aimed to develop a new meteorological drought index to describe and forecast drought based on various artificial intelligence (AI) models: decision tree (DT), generalized linear model (GLM), support vector machine, artificial neural network, deep learning, and random forest. A comparative assessment was conducted between the developed AI-based indices and nine conventional drought indices based on their correlations with multiple drought indicators. Historical records of five drought indicators, namely runoff, along with deep, lower, root, and upper soil moisture, were utilized to evaluate the models' performance. Different combinations of climatic datasets from Alice Springs, Australia, were utilized to develop and train the AI models. The results demonstrated that the rainfall anomaly drought index was the best conventional drought index, scoring the highest correlation (0.718) with the upper soil moisture. The highest correlation between the new and conventional indices was found between the DT-based index and the rainfall anomaly index at a value of 0.97, whereas the lowest correlation was 0.57 between the GLM and the Palmer drought severity index. The GLM-based index achieved the best performance according to its high correlations with conventional drought indicators, e.g., a correlation coefficient of 0.78 with the upper soil moisture. Overall, the developed AI-based drought indices outperformed the conventional indices, hence contributing effectively to more accurate drought forecasting and monitoring. The findings emphasized that AI can be a promising and reliable prediction approach for achieving better drought assessment and mitigation. [ABSTRACT FROM AUTHOR]

Drought is a complex natural hazard that occurs when a region experiences a prolonged period of dry conditions, leading to water scarcity and negative impacts on the environment. This study analyzed the recurrence of drought and wet spells in Baluchistan province, Pakistan. Reconnaissance Drought Index (RDI), Standardized Precipitation Evapotranspiration Index (SPEI), and Vegetation Condition Index (VCI) were used to analyze droughts in Baluchistan during 1986–2021. Statistical analysis i.e. run theory, linear regression, and correlation coefficient were used to quantify the trend and relationship between meteorological (RDI, SPEI) and agricultural (VCI) droughts. The meteorological drought indices (1, 3, 6, and 12-month RDI and SPEI) identified severe to extreme drought spells during 1986, 1988, 1998, 2000–2002, 2004, 2006, 2010, 2018–2019, and 2021 in most meteorological stations (met-stations). The Lasbella met-station experienced the most frequent extreme to severe droughts according to both the 12-month RDI (8.82%) and SPEI (15.38%) indices. The Dalbandin met-station (8.34%) follows closely behind for RDI, while Khuzdar (5.88%) comes in second for the 12-month SPEI. VCI data showed that Baluchistan experienced severe to extreme drought in 2000, 2001, 2006, and 2010. The most severe drought occurred in 2000 and 2001, affecting 69% of the study region. A positive correlation was indicated between meteorological (RDI, SPEI) and agricultural drought index (VCI). The multivariate indices can provide valuable knowledge about drought episodes and preparedness to mitigate drought impacts. [ABSTRACT FROM AUTHOR]

According to the written records and scores of grain harvest in the official historical documents of the Qing Dynasty in China, the spatial-temporal distribution and the impact caused by the 1759 AD drought in Northwest China were reconstructed, and the response of Chinese society to the drought at that time was summarized. In the spring and summer of 1759, vast areas of northern China suffered from drought, of which that experienced in the northwest region was the most serious. Starting from 27 April 1759, droughts covered Zhili, Shanxi, Shaanxi, and Gansu provinces, and the droughts in Gansu and northern Shaanxi provinces lasted until 23 July 1759. This severe drought caused the worst crop failure in Northwest China during the period 1730–1900. By implementing a series of disaster relief measures, the Qing government managed to ease the adverse societal impact of the drought in the summer of 1760. Among the relief measures, tax reduction and exemption in disaster-stricken areas, grain storage in the northwest region, and bumper agricultural harvests in Henan, Shandong, Jiangsu, and Anhui provinces in 1759 were the main reasons for the rapid recovery from the drought impacts. With better climatic conditions in the 18th century, China had higher agricultural harvest levels in the 18th century than in the 19th century. Favorable financial conditions increased drought relief efforts, which was the background for the greater societal adaptability to the climate disaster of 1759. [ABSTRACT FROM AUTHOR]

Trunk injection applies more nutrients in the correct volume and composition, delivering ideal results with fewer fertilizer treatments under drought-stress conditions. We used a completely randomized block design to examine the effects of trunk injection therapy on the development of drought stress tolerance in olive trees in arid climates. Treatments included seaweed extract (SWE), potassium amino acid chelate (PAC), calcium silicate (CS), and potassium silicate (PS) at five different concentrations: 0.25, 0.5, 1, 2, and 4% for each treatment. Each treatment consisted of four replications – four dry replications for each treatment and four irrigation controls – each receiving weekly irrigation. The findings showed that, in comparison to drought control, trunk injection of PAC at a concentration of 2% enhances the relative water content of leaf and proline and decreases electrolyte leakage (EL) and malondialdehyde (MDA) content. Chlorophyll a, carotenoids, and proline content are all significantly higher in the trunk after CS injection at a 4% concentration than in the control treatment. MDA and EL were also reduced. Injecting PS leads to an increase in proline and photosynthetic pigments. The SWE treatment improved the proline, relative leaf water content, and photosynthetic pigments. To sum up, trunk injection treatments under drought conditions improved plant photosynthetic pigments, increased proline content, prevented relative water content reduction, and prevented an increase in MDA and EL. In conclusion, among the several treatments, the use of 2% PS was the most effective at reducing the adverse effects of drought stress on olive plants. [ABSTRACT FROM AUTHOR]

Summary: Recent droughts have strongly impacted forest ecosystems and are projected to increase in frequency, intensity, and duration in the future together with continued warming. While evidence suggests that tree diversity can regulate drought impacts in natural forests, few studies examine whether mixed tree plantations are more resistant to the impacts of severe droughts.Using natural variations in leaf carbon (C) and nitrogen (N) isotopic ratios, that is δ13C and δ15N, as proxies for drought response, we analyzed the effects of tree species richness on the functional responses of tree plantations to the pan‐European 2018 summer drought in seven European tree diversity experiments.We found that leaf δ13C decreased with increasing tree species richness, indicating less drought stress. This effect was not related to drought intensity, nor desiccation tolerance of the tree species. Leaf δ15N increased with drought intensity, indicating a shift toward more open N cycling as water availability diminishes. Additionally, drought intensity was observed to alter the influence of tree species richness on leaf δ15N from weakly negative under low drought intensity to weakly positive under high drought intensity.Overall, our findings suggest that dual leaf isotope analysis helps understand the interaction between drought, nutrients, and species richness. [ABSTRACT FROM AUTHOR]

Accurately evaluating drought and its effects on the natural environment is difficult in regions with limited climate monitoring stations, particularly in the hyper-arid region of the Sultanate of Oman. Rising global temperatures and increasing incidences of insufficient precipitation have turned drought into a major natural disaster worldwide. In Oman, drought constitutes a major threat to food security. In this study, drought indices (DIs), such as temperature condition index (TCI), vegetation condition index (VCI), and vegetation health index (VHI), which integrate data on drought streamflow, were applied using moderate resolution imaging spectroradiometer (MODIS) data and the Google Earth Engine (GEE) platform to monitor agricultural drought and assess the drought risks using the drought hazard index (DHI) during the period of 2001–2023. This approach allowed us to explore the spatial and temporal complexities of drought patterns in the Najd region. As a result, the detailed analysis of the TCI values exhibited temporal variations over the study period, with notable minimum values observed in specific years (2001, 2005, 2009, 2010, 2014, 2015, 2016, 2017, 2019, 2020, and 2021), and there was a discernible trend of increasing temperatures from 2014 to 2023 compared to earlier years. According to the VCI index, several years, including 2001, 2003, 2006, 2008, 2009, 2013, 2015, 2016, 2017, 2018, 2020, 2021, 2022, and 2023, were characterized by mild drought conditions. Except for 2005 and 2007, all studied years were classified as moderate drought years based on the VHI index. The Pearson correlation coefficient analysis (PCA) was utilized to observe the correlation between DIs, and a high positive correlation between VHI and VCI (0.829, p < 0.01) was found. Based on DHI index spatial analysis, the northern regions of the study area faced the most severe drought hazards, with severity gradually diminishing towards the south and east, and approximately 44% of the total area fell under moderate drought risk, while the remaining 56% was classified as facing very severe drought risk. This study emphasizes the importance of continued monitoring, proactive measures, and effective adaptation strategies to address the heightened risk of drought and its impacts on local ecosystems and communities. [ABSTRACT FROM AUTHOR]

In 2022, a severe drought and heatwave occurred in the middle and lower reaches of the Yangtze River Basin. Previous studies have highlighted the severity of this event, yet the relevance of soil moisture (SM), as well as vapor pressure deficit (VPD) and vegetation damage, remained unclear. Here, we utilized solar-induced chlorophyll fluorescence (SIF) and various flux data to monitor the impact of drought on vegetation and analyze the influence of different environmental factors. The results indicated a severe situation of drought and heatwave in the Yangtze River Basin in 2022 that significantly affected vegetation growth and the ecosystem carbon balance. SIF and NDVI have respective advantages in reflecting damage to vegetation under drought and heatwave conditions; SIF is more capable of capturing the weakening of vegetation photosynthesis, while NDVI can more rapidly indicate vegetation damage. Additionally, the correlation of SM and SIF are comparable to that of VPD and SIF. By contrast, the differentiation in the severity of vegetation damage among different types of vegetation is evident; cropland is more vulnerable compared to forest ecosystems and is more severely affected by drought and heatwave. These findings provided important insights for assessing the impact of compound drought and heatwave events on vegetation growth. [ABSTRACT FROM AUTHOR]

Drought events have been linked with the enhancements of organic aerosols (OAs), but the mechanisms have not been comprehensively understood. This study investigates the relationships between the monthly standardized precipitation–evapotranspiration index (SPEI) and surface OA in the contiguous United States (CONUS) during the summertime from 1998 to 2018. OA under severe drought conditions shows a significant increase in mass concentrations across most of the CONUS relative to non-drought periods, with the Pacific Northwest (PNW) and Southeast United States (SEUS) experiencing the highest average enhancement of 1.79 µgm-3 (112 %) and 0.92 µgm-3 (33 %), respectively. In the SEUS, a linear regression approach between OA and sulfate was used to estimate the epoxydiol-derived secondary organic aerosol (IEPOX SOA), which is the primary driver of the OA enhancements under droughts due to the simultaneous increase in emissions of biogenic volatile organic compounds (VOCs; such as isoprene and monoterpene) and sulfate. The rise in sulfate is mainly caused by the reduced wet deposition because of the up to 62 % lower precipitation amount. In the PNW, OA enhancements are closely linked to intensified wildfire emissions, which raise OA mass concentrations to be 4–8 times higher relative to non-fire conditions. All 10 Earth system models participating in the sixth phase of the Coupled Model Intercomparison Project (CMIP6) can capture the slopes between SPEI and OA in the PNW, with CESM2-WACCM and GFDL-ESM4 performing the best and worst in predicting the OA enhancement under severe droughts. However, all models significantly underestimate the OA increase in the SEUS, with Nor-ESM2-LM and MIRCO6 showing relatively better performance. This study reveals the key drivers of the elevated OA levels under droughts in the CONUS and underscores the deficiencies of current climate models in their predictive capacity for assessing the impact of future droughts on air quality. [ABSTRACT FROM AUTHOR]

Drought may facilitate the invasion process of invasive plants, mainly because invasive plants can obtain a stronger growth competitiveness than native plants under drought. It is therefore imperative to illuminate the mechanisms underlying the successful invasion of invasive plants under drought, with a particular focus on the differences in the resistance of invasive and native plants to drought. This study aimed to elucidate the differences in the resistance between the invasive plant Amaranthus spinosus L. and the native plant A. tricolor L. to drought under a gradient of drought. The resistance of co-cultivated A. spinosus to drought was significantly higher than that of co-cultivated A. tricolor under light drought. Hence, A. spinosus may obtain a stronger competitive advantage than A. spinosus under co-cultivation conditions when treated with light drought. The resistance of the two plants to drought may be predominantly influenced by their height and biomass. This present study also defines a method for evaluating the stress resistance of a given plant species to stress by calculating the stress resistance index. This present study offers a robust theoretical foundation for determining the stress resistance of a given plant species and the environmental management of A. spinosus under drought. [ABSTRACT FROM AUTHOR]

Drought stress has serious effects on the growth and yield of wheat in both productivity and quality and is an abiotic factor. Traditional methods of crop drought stress monitoring have some deficits. This work has been conducted in order to enhance these conventional methods by proposing a new deep learning approach. This paper has presented a deep learning-based model customized for monitoring drought stress in winter wheat during the critical growth stages. Drought-afflicted winter wheat images were captured at three crucial phases: rising–jointing, heading–flowering, and flowering–maturity. These images are correlated against soil moisture data to construct a comprehensive dataset. DenseNet121 was chosen as the network model since it extracts features from images relating to phenotypes. Several factors, like training methods, learning rate adjustment, and addition of the attention mechanism, are optimized in eight sets of experiments. This provided the final DenseNet-121 model with an average recognition accuracy of 94.67% on the test set, which means that monitoring drought stress during wheat growth's key periods is feasible and effective. [ABSTRACT FROM AUTHOR]

Armed conflicts can lead to environmental degradation, thereby threatening the basis of people's livelihoods and wellbeing. Identifying areas where conflicts drive environmental degradation is important for designing effective recovery strategies, but this is inherently challenging in insecure contexts. We use a case study in Tigray, Ethiopia to illustrate how open-source satellite data can be used to support the identification of woody vegetation loss during armed conflicts in situations where ground-based assessments are difficult or impossible. Areas of potential woody vegetation loss extend across 930 km2 (approximately 4% of the area occupied by forest and other woody vegetation in Tigray) and appear to be concentrated mostly along major roads; however, vegetation recovery has continued during the war across a significantly larger area (approximately 2600 km2). Spatial patterns of woody vegetation loss appear to be unrelated to drought conditions and large-scale wildfires. Based on these observations and anecdotal evidence of deforestation, we propose that it may be conflict-driven deforestation, caused by increases in fuel wood demands, that are driving the woody vegetation losses in some areas of Tigray. Eventual recovery efforts will have to consider the loss in landscape health during the war in areas where woody vegetation has declined, and include efforts to restore this vegetation to ensure both food security and livelihoods. Open access satellite data, together with ground-based data collection, could inform such post-war restoration efforts by helping identify degraded areas at a regional scale. [ABSTRACT FROM AUTHOR]

Rhizobacteria play a crucial role in plant growth and yield, stimulating primary production and improving stress resistance. Climate change has several consequences worldwide that affect arable land and agriculture. Studies on plant–soil–microorganism interactions to enhance plant productivity and/or resistance to abiotic stress may open new perspectives. This strategy aims to make agricultural‐relevant plant species able to complete their biological cycle in extreme soils with the help of inoculated or primed plant growth‐promoting rhizobacteria (PGPR).We provide an overview of the evolution of interest in PGPR research in the last 30 years through: (i) a quantitative search on the Scopus database; (ii) keyword frequencies and clustering analysis, and (iii) a keyword network and time‐gradient analysis.The review of scientific literature on PGPR highlighted an increase in publications in the last 15 years, and a specific time gradient on subtopics, such as abiotic stresses. The rise in PGPR as a keyword co‐occurring with salinity and drought stresses aligns with the growing number of papers from countries directly or partly affected by climate change.The study of PGPR, its features, and related applications will be a key challenge in the next decades, considering climate change effects on agriculture. The increased interest in PGPR leads to deeper knowledge focused specifically on researching agriculturally sustainable solutions for soils affected by salinity and drought. [ABSTRACT FROM AUTHOR]

Enhancing forest drought resilience is important for preserving ecosystem services in the face of climate change, but operational management methods for boreal forests aiming to preserve ecosystem services under drought are still largely missing. This study explores the use of satellite remote sensing to monitor vegetation stress phases related to drought progression and to quantify both short- and long-term impacts on forest growth. Data from the Sentinel-2 satellite mission were used to calculate the response of vegetation indices across six forest types, using the time period from 2015 to 2017 as a reference dataset. The percentual difference between the drought year of 2018 and the reference period was used to represent disturbance intensity and the system's capability to resist it. Additionally, the recovery time was taken into consideration. Breakpoint detection with daily temporal resolution was used to quantify the response time of each forest type in relation to the onset date of meteorological drought. Results indicate that Sentinel-2 data can be used to monitor vegetation stress associated with drought progression and estimate the characteristics of forest resilience. High temporal resolution observations should be prioritized over annual maximum vegetation index values to determine the intensity of disturbance. Consistent severe impacts were observed in areas with limited soil moisture availability. The recovery time of forests took up to 4 years. Drought exposure during consecutive years could be especially damaging for species requiring a longer recovery time than a single growing season. Sentinel-2-based monitoring approach could benefit decision-support systems for forest management aiming to enhance drought resilience. [ABSTRACT FROM AUTHOR]

Accurately and reliably predicting droughts under multiple models of Global Climate Models (GCMs) is a challenging task. To address this challenge, the Multimodel Ensemble (MME) method has become a valuable tool for merging multiple models and producing more accurate forecasts. This paper aims to enhance drought monitoring modules for the twenty-first century using multiple GCMs. To achieve this goal, the research introduces a new weighing paradigm called the Multimodel Homo-min Pertinence-max Hybrid Weighted Average (MHmPmHWAR) for the accurate aggregation of multiple GCMs. Secondly, the research proposes a new drought index called the Condensed Multimodal Multi-Scalar Standardized Drought Index (CMMSDI). To assess the effectiveness of MHmPmHWAR, the research compared its findings with the Simple Model Average (SMA). In the application, eighteen different GCM models of the Coupled Model Intercomparison Project Phase 6 (CMIP6) were considered at thirty-two grid points of the Tibet Plateau region. Mann–Kendall (MK) test statistics and Steady States Probabilities (SSPs) of Markov chain were used to assess the long-term trend in drought and its classes. The analysis of trends indicated that the number of grid points demonstrating an upward trend was significantly greater than those displaying a downward trend in terms of spatial coverage, at a significance level of 0.05. When examining scenario SSP1-2.6, the probability of moderate wet and normal drought was greater in nearly all temporal scales than other categories. The outcomes of SSP2-4.5 demonstrated that the likelihoods of moderate drought and normal drought were higher than other classifications. Additionally, the results of SSP5-8.5 were comparable to those of SSP2-4.5, underscoring the importance of taking effective actions to alleviate drought impacts in the future. The results demonstrate the effectiveness of the MHmPmHWAR and CMMSDI approaches in predicting droughts under multiple GCMs, which can contribute to effective drought monitoring and management. [ABSTRACT FROM AUTHOR]

The root microbiota plays a crucial role in assisting the plant host in combating various biotic and abiotic stresses, notably drought, which poses a significant threat to global food security. Despite extensive efforts to understand the shifts in rhizosphere and endosphere bacteriomes, there remains a gap in comprehending how drought stress influences the co-occurring network patterns within these compartments and their ecological functional potentials. To address this gap, a pot experiment was conducted with two treatments: continuous flooding as a control and drought treatment. Bulk soil, rhizosphere, and endosphere samples were collected and subjected to high-throughput sequencing and bioinformatics analysis. The results revealed that drought stress significantly reduced the rice biomass but increased the Shannon diversity index in both the rhizosphere and endosphere bacterial communities with no observable effect on richness across compartments. Additionally, drought treatment markedly altered the community structure and bacterial assemblages in these compartments, resulting in the specific enrichment of Actinobacteriota, Gemmatimonadetes, and Patescibacteria, while Bacteroidetes and Firmicutes were depleted in the rhizosphere and endosphere. Furthermore, drought heightened the complexity of the co-occurring networks and the proportions of positive links across all sampling compartments; this effect was accompanied by an increase in the number of connectors in the bulk soil and rhizosphere, as well as module hubs in the rhizosphere. Functional potential prediction indicated that drought stress significantly altered multiple potential ecological functions across all sampling compartments, particularly enriching functions related to the oxidation of sulfur, manganese, and hydrogen in the bulk soil, while functions associated with iron oxidation were significantly depleted in the rhizosphere. Overall, our results demonstrate that under drought stress, rice may specifically enrich certain bacterial taxa and enhance their positive interactions within its root system to improve adaptation. [ABSTRACT FROM AUTHOR]

ROOTHAIRLESS (RHL) is a typical type of basic helix‐loop‐helix (bHLH) transcription factor (TF), which has been reported to participate in various aspects of plant growth and in response to stress. However, the functions of RHL subfamily members in moso bamboo (Phyllostachys edulis) remain unknown. In this study, we identified 14 bHLH genes (PeRHL1–PeRHL14) in moso bamboo. Phylogenetic tree and conserved motif analyses showed that PeRHLs were clustered into three clades. The expression analysis suggested that PeRHL4 was co‐expressed with PeTIP1‐1 and PePHT1‐1 in moso bamboo. Moreover, these three genes were all up‐regulated in moso bamboo under drought stress and phosphate starvation. Y1H, DLR and EMSA assays demonstrated that PeRHL4 could activate the expression of PeTIP1‐1 and PePHT1‐1. Furthermore, overexpression of PeRHL4 could increase both drought and phosphate starvation tolerance in transgenic rice, in which the expression of OsTIPs and OsPHT1s was significantly improved, respectively. Overall, our results indicated that drought stress and phosphate starvation could induce the expression of PeRHL4, which in turn activated downstream genes involved in water and phosphate transport. Collectively, our findings reveal that PeRHL4 acting as a positive regulator contributes to enhancing the tolerance of moso bamboo under drought stress and phosphate starvation. Summary statement: Drought stress and phosphate starvation trigger intricate signalling networks that impact plant growth. This study presents PeRHL4 as a regulatory factor to activate downstream genes for water and phosphate transport, potentially bolstering the tolerance of moso bamboo under stresses. [ABSTRACT FROM AUTHOR]

The climatic conditions in Hunan province are complex and the probability of drought occurrence is high. To reveal the probability characteristics of drought events in various climatic regions of Hunan province (central Hunan, northeast Hunan, northwest Hunan, western Hunan, and southern Hunan), based on meteorological data from 97 meteorological stations in Hunan province during 1961-2020, standardized precipitation evapotranspiration index (SPEI) and Copula function were used to extract the duration and severity of drought events, and to study the co-occurrence recurrence periods of drought duration and severity were studied in each climatic region of Hunan province. The results showed that: (1) along the direction of southern Hunan, central Hunan, northeast Hunan, northwest Hunan, and western Hunan, the number of drought events in the climatic region was from more to less, and the value range of drought events duration and severity was from small to large. (2) When fitting the optimal marginal distribution function of drought duration and severity respectively, the number of stations fitted by GEV function exceeds 60%, and the fitting effect of the optimal marginal distribution function of drought severity was better than that of drought duration. When the joint function of drought duration and the optimal marginal distribution of severity was established, the Frank Copula function was applied to more than 50% of the sites. (3) Southern Hunan was prone to shorter duration and greater severity of drought events, while western Hunan, northwest Hunan, and some areas of northeast Hunan were prone to longer duration and greater severity of drought events. Central Hunan was not only prone to drought events with long duration and high severity but also to drought events with short duration and high severity in the southern part of central Hunan. There were differences in the probability characteristics of drought events in different climatic regions in Hunan province, and measures can be taken to reduce the harm of drought. [ABSTRACT FROM AUTHOR]

The Mediterranean region contains some of the areas with the highest urban density in the world, and these areas keep expanding, making this region a "hotspot" of climate change. Life in the Mediterranean unfolds predominantly outdoors throughout the year, exposing its inhabitants to an evolving climate that is progressively harsher and punctuated by increasingly frequent extreme weather events. More and more people are going to be exposed to severe heat waves, droughts, water shortage, dust storms, forest fires and poor air quality on the one hand, and torrential rains and floods on the other hand. The urban heat island further increases thermal stress of city dwellers and plays a key role in citizens' health and well‐being. In this exhaustive review, based on state‐of‐the‐art studies we delve into the realm of climate change and extreme weather phenomena as they intersect with urban populations in Mediterranean cities, both in the present and in the foreseeable future. Our focus lies on identifying knowledge gaps, inconsistencies in observed climatic hazards and shortcomings in assessing the associated risks and their societal and environmental ramifications. Moreover, we undertake a comprehensive survey of future predictions exploring the variables thermal stress, air pollution, air quality and characteristics of the hydro‐climatic systems, that is, droughts, fires and floods. Yet, critical knowledge gaps persist in understanding the science, the coping mechanisms, the strategies for preparedness and adaptation and the intricate interplay between these facets and societal dynamics. The developing countries in the Mediterranean region stand exceptionally vulnerable. It is imperative for more affluent nations to share their expertise and extend assistance to less developed counterparts, aiding them in navigating climate‐related challenges, devising adaptive strategies and facilitating their implementation. [ABSTRACT FROM AUTHOR]

Drought occurs when there is a sustained decrease in rainfall over an extended period, impacting the socio‐cultural and environmental aspects of humans and other living beings. The geographic distribution and timing of droughts play a crucial role in drought management and mitigation strategies. Identifying and predicting the onset of droughts in specific regions, especially in watershed areas, is a primary concern in the field of hydrology. This study focuses on how the spatiotemporal patterns of drought are developing in Turkish Basins using detailed data on Terrestrial Water Storage (TWS), precipitation, and temperature at the pixel level. GRACE (Gravity Recovery and Climate Experiment), PERSIANN (Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks), and WorldClim (World Climate) data sets are employed to assess long‐term changes of drought on a basin‐scale. Spatial analyses are conducted in a Geographic Information System (GIS) environment for the derivation of basinal monthly mean, minimum, and maximum statistics of TWS, precipitation, and temperature anomalies within Turkish Basins. Time series analyses are implemented to investigate the temporal evolution of droughts in these basins, for the basinal monthly mean, minimum, and maximum statistics obtained. The Mann–Kendall trend test and Pettitt change point detection tests are used to assess the statistical significance of the calculated trends and to expose the existence of any change point therein, respectively. The findings of the study indicate that Turkiye faces a significant risk of drought development in nearly all its basins, particularly after 2016. The GRACE dataset provides realistic insights into the temporal behaviour of hydrological droughts. PERSIANN is effective in identifying years with extreme meteorological conditions, and the standardized precipitation index (SPI) shows similar effectiveness, while they are ineffective in exposing significant trends due to the nature of the precipitation data. WorldClim data proves insufficient for modelling the temporal behaviour of droughts in these basins. [ABSTRACT FROM AUTHOR]

Awareness of the potential threat posed by drought necessitates the implementation of appropriate procedures to enable effective and systematic actions aimed at mitigating, or at least partially limiting, the impacts of drought events. This paper seeks to analyze the spatial and temporal changes of atmospheric drought in the period 1961–2020 and assesses drought hazards in southwest Bulgaria, which is a region susceptible to periodic water shortages. In this study, the standardized precipitation evaporation index (SPEI), accounting for both precipitation and temperature changes, was used to analyze drought characteristics. The analysis reveals significant temporal changes and spatial differences in drought patterns across southwest Bulgaria. The northeastern part of the region, including the Sofia district, exhibits the lowest risk of drought, while the central part of the region shows a tendency toward moderate and occasional low drought events. Some stations, particularly in the southern part of the region, consistently experienced more severe drought conditions (Blagoevgrad and Sandanski), as indicated by negative SPEI values in different time scales (3, 6, and 12 months). Results indicate an increased frequency of droughts during 1990–2020 compared to 1961–1990, which was driven by climate change and human activities. Across all stations and in both SPEI time scales, the period from the early to mid-1990s was characterized by significant droughts. The study of drought hazards using short-term and long-term SPEI analysis reveals different levels of drought risk and increased hazard from the northern to southern parts of the study area. The share of areas with a high drought hazard exceeds 40% of the territory in the areas with a transitional and continental-Mediterranean climate. Based on the results, the paper highlights the need to integrate drought risk assessments with regional planning to improve agricultural resilience and water resource management in response to anticipated droughts, especially in drought-prone areas such as southwest Bulgaria. [ABSTRACT FROM AUTHOR]

Drought is an extreme phenomenon which occurs due to a prolonged duration of peculiarly low precipitation in a region. This can affect various sectors like agriculture, livestock, and human health among others. Countries like Pakistan which have agriculture-based economy can have severe consequences due to drought. In this study, Standardized Precipitation Index (SPI) and Standardized Precipitation Evapotranspiration Index (SPEI) are applied to examine drought features at different time scales over Punjab Province which is the food basket for Pakistan. The drought occurrence was examined through drought frequency, concentrating on spatial and temporal scales and considering different geomorphologies. A modified Mann-Kendall test and multiple linear regression are used to examine monthly data from 12 weather stations collected between 1980 and 2020. Stations at high elevations have very variable precipitation, which can lead to periodic droughts. Surprisingly, SPEI shows more drought sensitivity than SPI. The severity of the drought has decreased recently, especially after the 1998–2002 peak period. Correlation analysis demonstrates a substantial link between SPI and SPEI at high elevation stations, with Murree displaying the strongest correlation (0.9334) on a one-month time frame, and Bahawalpur exhibiting a comparably lower correlation (0.6824). Positive trends in SPI and SPEI values are revealed by Mann-Kendall trend tests, which are most prominent at higher elevations and on the northern Punjab. On a one-month time scale, the Mianwali station has the strongest trend in SPEI (0.1497), whereas Bahawalnagar has negligible trends in both SPI (0.0214) and SPEI (0.0459). At high elevation sites, the frequency of drought is constantly high, and SPEI routinely detects greater drought at low elevations. Similar drought frequencies are shown by both indices for the northern region of Punjab. The results of a multiple linear regression model demonstrate the significant impact of meteorological variables on monthly mean precipitation, which advances our knowledge of Punjab's spatiotemporal drought dynamics and provides important information for planning for resilience and water resource management. [ABSTRACT FROM AUTHOR]

Drought is a natural disaster that negatively impacts agricultural crops. Understanding the mechanisms of water deficit response is key to improving drought-tolerant crops. This study focused on comprehending the drought-tolerant mechanisms of a mutant chili, CaWDT-2, by investigating its physiological phenotypes and gene expression under PEG-induced drought condition compared to Tavee 60 as the original cultivar. Chili physiological status was monitored by shoot height, root length, leaf number, leaf area, shoot mass and root mass at 10 d after drought initiation. Relative water content (RWC), malondialdehyde (MDA), proline, soluble sugar and sucrose were measured during drought and after recovery. Transcriptome analysis using sequencing of RNA (RNA-seq) was employed to examine gene expression profiling under drought for 24 h. Results revealed diverse changes in physiological mechanism in response to drought between CaWDT-2 and Tavee 60 cultivars. Comparative transcriptomic analysis is helpful in understanding the differences in drought tolerance mechanisms between 2 crop varieties. Major differences that emerged from the physiological and transcriptomic analyses included drought-stressed injury level, proline accumulation, root cell wall adaptation, ABA biosynthesis, stress detoxification, heat shock proteins and transcription factors. Our data will contribute to further research in developing droughttolerant crops. An improved understanding of drought tolerance mechanisms will enhance agricultural resilience and mitigate the impact of drought on crop yield. [ABSTRACT FROM AUTHOR]

Context: Quenda (bandicoots , Isoodon fusciventer) have shown a major decline in range since European settlement, contracting to the more mesic coastal and forest zones in south-west Western Australia. Key actions to recover this species include broad-scale fox control, cat control and reintroductions. Most reintroductions have been to coastal and forest habitats. Aims: To monitor the reintroduction of quenda to fox-free habitat of Wadderin Sanctuary in the wheatbelt of Western Australia, close to the eastern and drier margin of the species' former range. Methods: Relative abundance of the population was monitored over a 12-year period by regular standardised trapping throughout the sanctuary. Key results: Quenda were reintroduced in 2010 and have persisted for >12 years. They were protected from fox predation by an exclusion fence, but were subject to a low level of cat predation for the first 8 years. Quenda showed both a ~20% drop in mean body condition over time and a trend of decreasing number of pouch young per female over time, likely a result of a succession of dry years and intra-and inter-specific competition for food resources. However, despite this, the index of abundance suggests that quenda numbers substantially increased, aided by high annual recruitment, in years following removal of the feral cat. Conclusions: Quenda appear resilient at this site despite consecutive years of very low rainfall and apparent competition for food resources. Implications: Quenda seem able to persist on the drier margin of their former range when protected from high levels of predation. Reintroduction is a key strategy for re-establishing threatened species. Quenda (bandicoots, Isoodon fusciventer) were returned to the geographic and climatic margin of their former range after an absence of >40 years, persisting for more than 12 years despite drought and likely inter-and intra-specific competition for food resources. Minimising predation from foxes and feral cats was critical to the success. [ABSTRACT FROM AUTHOR]

Faced with pollinator declines, cities could serve as refuges for biodiversity conservation by managing floral resources in public green spaces. Ornamental plants could play an important role in attracting pollinators because they form part of urban floral management. However, knowledge of how their floral traits respond to drought is lacking, and it is unknown whether they will be suitable for pollinators under future climates. The main objective of this study was to determine the covariation of floral traits of ornamental plant species and effects of drought on them. To this end, in a city greenhouse we measured floral traits of eight ornamental species commonly used in urban green spaces in France. We subjected the plants to a control treatment or a drought treatment, reducing the volume and frequency of watering. We observed interspecific variability in floral traits among these species and a change in covariation between the traits pollen quantity and nectar quantity in the drought treatment. Drought influenced morphological traits related to floral display more than other floral traits, with mean decreases of 28 % in floral height, 35 % in floral area and 58 % in the number of floral units. Ornamental plants seemed attractive to different morphotypes of pollinators depending on their floral unit number, nectar sugar concentration or nectar tube depth, with most visits made by Hymenoptera. These results are expected to encourage green-space managers to select urban plants according to their functional characteristics and adapt their choice of plants to climate change. [ABSTRACT FROM AUTHOR]

Genes in the glycogen synthase kinase 3 (GSK3) family are essential in regulating plant response to stressful conditions. This study employed bioinformatics to uncover the GSK3 gene family from the sunflower genome database. The expressions of GSK3 genes in different tissues and stress treatments, such as salt, drought, and cold, were assessed using transcriptome sequencing and quantitative real-time PCR (qRT-PCR). The study results revealed that the 12 GSK3 genes of sunflower, belonging to four classes (Classes I–IV), contained the GSK3 kinase domain and 11–13 exons. The majority of GSK3 genes were highly expressed in the leaf axil and flower, while their expression levels were relatively lower in the leaf. As a result of salt stress, six of the GSK3 genes (HaSK11 , HaSK22 , HaSK23 , HaSK32 , HaSK33 , and HaSK41) displayed a notable increase in expression, while HaSK14 and HaSK21 experienced a significant decrease. With regard to drought stress, five of the GSK3 genes (HaSK11 , HaSK13 , HaSK21 , HaSK22 , and HaSK33) experienced a remarkable rise in expression. When exposed to cold stress, seven of the GSK3 genes (HaSK11 , HaSK12 , HaSK13 , HaSK32 , HaSK33 , HaSK41 , and HaSK42) showed a substantial increase, whereas HaSK21 and HaSK23 had a sharp decline. This research is of great importance in understanding the abiotic resistance mechanism of sunflowers and developing new varieties with improved stress resistance. Supplementary Material Supplementary Material File [ABSTRACT FROM AUTHOR]

Extreme climatic events such as droughts, floods, cyclones, and landslides have adversely affected a homegarden that consists of its inherited characteristics as a secondary forest along with alterations made by human. Households, as the major beneficiary of homegardens, have the responsibility to maintain the homegarden incorporating its structure and composition with functions of the household to make the homegarden resilient to adverse effects. To assess the current climate resilience level of a homegarden, data were collected through an in-depth survey from 435 homegardens in Hambantota, Jaffna, Matale, and Ratnapura districts in Sri Lanka. Climate Resilience Index (CRI) of homegarden was constructed based on absorptive and adaptive capacities using the 13 variables. The mean value of the CRI was 0.375 (± 0.005) which ranged from 0.019 to 0.616. As per the multiple regression analysis performed taking the CRI as the dependent variable, the constructed models were complex, and all the variables were required to determine the level of resilience of a homegarden. Based on the CRI values five categories of homegardens were identified as very low, low, moderate, high and very high resilient. Accordingly, key variables affecting the level of resilience of a homegarden were; application of soil and water conservation methods, requirement of soil conservation, presence of woody trees, above-ground biomass, number of canopy strata, experience in farming and technical knowledge on farming, species richness of tree were selected as resilient variables that indicate absorptive and adaptive capacities. The resilience level of a homegarden can be changed, by altering these variables together. [ABSTRACT FROM AUTHOR]

This study uses Multifractal Detrended Fluctuation Analysis to examine the scaling behavior and spatiotemporal variability of drought indicators. We employ two hybrid drought indicators—the GRACE Root Zone Soil Moisture Percentile (SMI) and Evaporative Demand Drought Index (EDDI)—to elucidate agricultural drought characteristics, and we quantify meteorological drought using the Standardized Precipitation Index (SPI). Our investigation was carried out in the United States in the California and Mississippi watersheds, each characterized by distinct agricultural climate conditions and planting systems. The changes in drought indicators exhibit multifractality primarily derived from the long-term memory embedded within the time series. Spatially, the increment sequence of SPI displays pronounced dependence in almost all areas. Specifically, the changes in SPI demonstrate persistence, as the Hurst exponents changed from 0.53 to 0.58 in California, revealing the possibility of a degree of trend continuation (albeit, not very strong) in the future. A regular summary cannot be obtained for Mississippi, since the Hurst exponent ranges from 0.46 to 0.51 for the increment sequence of SPI in that watershed. However, the increment sequences for the agricultural drought indicators exhibit obvious short-term persistence (anti-persistence), indicating that future drought trends may be discontinuous. The variations in the strength of anti-persistence among agricultural drought indicators can be attributed to geographical differences, diverse irrigation strategies, and varying cropping systems. No significant evolution pattern is evident for the scaling structure of drought processes due to minor variations in external controlling factors, such as rainfall and temperature, within the drought process. [ABSTRACT FROM AUTHOR]

Pastoral communities in Ethiopia's Bale Zone face a constant threat: drought. The Bale lowlands are Particularly vulnerable due to unpredictable rainfall patterns. A 4-year drought cycle had gripped the region, as reported by the pastoralists themselves. Rising temperatures and declining rainfall painted a concerning picture, leading to a cascade of problems: crop failures, food insecurity, outbreaks of diseases, and increased child school dropout rates. This in-depth study aimed to shed light on the impact of drought on these communities and their remarkable capacity to adapt. By bridging the knowledge gap on drought's influence and local coping mechanisms, the study hoped to inform future interventions. The objectives were to identify the impact of drought on Bale's pastoral communities and to identify the coping mechanisms employed by these communities. The study utilized a mixed-methods approach to capture both qualitative and quantitative data. Data collection techniques included: Engaging with knowledgeable community leaders provided valuable insights into historical trends, community perceptions, and local decision-making processes, Facilitating group discussions allowed community members to share their experiences, concerns, and coping mechanisms in a collaborative setting and administering standardized surveys to a representative sample of households allowed for the quantification of drought's impact and the prevalence of various adaptation strategies. The Results shows all study locations experienced drought for four consecutive years (100%), Pastoralists reported rising temperatures and declining rainfall. The drought resulted in, Crop failures, Food insecurity, Livestock deaths, increased human and livestock diseases increased child school dropout rates. The study concluded that despite the challenges, the study revealed a heartening story of resilience. Bale's pastoral communities have not succumbed to despair. Instead, they have developed a multifaceted approach to cope with drought, including: Utilizing existing water sources and creating communal grazing areas for better water conservation, Splitting herds to reduce grazing pressure, implementing early morning grazing to capitalize on dew, diversifying livestock breeds, and strategically destocking herds before droughts to ensure long-term herd sustainability, Diversifying income through trade, transportation services, and petty trade to reduce dependence on livestock production during droughts. Leveraging the enduring strength of traditional social safety nets ("hirpa," "dare," and "hameessa") for crucial support and assistance during hardships. The study underscores the importance of supporting these existing strategies. Policymakers and NGOs can play a vital role by strengthening social safety nets, promoting the adoption of droughtresistant agricultural practices, investing in research on improved water management techniques and drought-resistant crop varieties. [ABSTRACT FROM AUTHOR]

Drought stress severely restricts crop yields. Changes in root morphology and function are critical to rice performance under drought conditions, affecting water uptake efficiency, hormone regulation, and nutrient absorption. This study explores the responses of two rice lines, IZ036 with a small root system and IZ144 with a large root system, to drought stress (soil water potential of – 30 ± 5 kPa). The results showed that drought stress significantly inhibited the growth and yield of both rice lines by 35.6–58.1%. Under drought stress, the root-to-shoot ratio of IZ144 increased by 17.8–68.0%, while IZ036 decreased by 10.2–59.1%. While IZ036 experienced a significant reduction in leaf water potential under drought stress, no such impact was observed in IZ144. Both varieties exhibited altered tissue anatomy under drought stress, including, reduced leaf vascular size, increased proportion of vascular bundles in root cross-section, and changes in root thickness. Notably, IZ036 displayed cell and vessel shrinkage and leaf deformation. In response to drought stress, both rice lines exhibited elevated concentrations of auxin, salicylic acid and abscisic acid (ABA) in leaves and increased ethylene and gibberellin (GA) in roots. Notably, IZ144 had significantly higher ABA, cytokinin (CTK), GA, and auxin levels in leaves and CTK in roots than IZ036. Overall, our findings highlight the superior drought tolerance of IZ144 over IZ036, as evidenced by enhanced physiological and anatomical performances and more effective hormone distribution in leaves and roots, indicating the importance of root size in determining drought stress resilience in rice. [ABSTRACT FROM AUTHOR]

Background: Autumn and winter Santa Ana Winds (SAW) are responsible for the largest and most destructive wildfires in southern California. Aims: (1) To contrast fires ignited on SAW days vs non-SAW days, (2) evaluate the predictive ability of the Canadian Fire Weather Index (CFWI) for these two fire types, and (3) determine climate and weather factors responsible for the largest wildfires. Methods: CAL FIRE (California Department of Forestry and Fire Protection) FRAP (Fire and Resource Assessment Program) fire data were coupled with hourly climate data from four stations, and with regional indices of SAW wind speed, and with seasonal drought data from the Palmer Drought Severity Index. Key results: Fires on non-SAW days were more numerous and burned more area, and were substantial from May to October. CFWI indices were tied to fire occurrence and size for both non-SAW and SAW days, and in the days following ignition. Multiple regression models for months with the greatest area burned explained up to a quarter of variation in area burned. Conclusions: The drivers of fire size differ between non-SAW and SAW fires. The best predictor of fire size for non-SAW fires was drought during the prior 5 years, followed by a current year vapour pressure deficit. For SAW fires, wind speed followed by drought were most important. Fires ignited on Santa Ana Wind days are the largest and most destructive fires but other fires are more numerous and account for greater area burned. Fire indices on days after ignition are important predictors of fire size, but drought and wind speed are most closely tied to fire size. [ABSTRACT FROM AUTHOR]

The Madeira River, a major tributary of the Amazon River, often undergoes severe flood and drought conditions. This study seeks to investigate the climate processes associated with the opposing extreme precipitation events in the Madeira River basin and to relate them to river discharge variability based on a flood awareness dataset. Despite the uncertainty in the observational datasets, the annual precipitation cycle exhibits a rainy season from November to March. A significant result is the high correlation between the rainy season variability in the Madeira River basin and the sea surface temperature (SST) anomalies in the tropical North Atlantic Ocean and the southwestern South Atlantic Ocean. This result indicates that improving the Atlantic SST representation in climate modeling allows for capturing extreme precipitation events in the region. In addition to this impact, certain Madeira River tributaries present significant climate trends. The river discharge variability reveals an increase in hydrological extremes in recent years in the upper sector, but more significantly, in the lower basin, where it has reduced by more than 400 m3/s per decade. These findings highlight the need to improve in situ data and climate and hydrological modeling, with a focus on describing the intense climate variability and trends in river discharges. [ABSTRACT FROM AUTHOR]

This study addresses the critical issue of drought zoning in Canada using advanced deep learning techniques. Drought, exacerbated by climate change, significantly affects ecosystems, agriculture, and water resources. Canadian Drought Monitor (CDM) data provided by the Canadian government and ERA5-Land daily data were utilized to generate a comprehensive time series of mean monthly precipitation and air temperature for 199 sample locations in Canada from 1979 to 2023. These data were processed in the Google Earth Engine (GEE) environment and used to develop a Convolutional Neural Network (CNN) model to estimate CDM values, thereby filling gaps in historical drought data. The CanESM5 climate model, as assessed in the IPCC Sixth Assessment Report, was employed under four climate change scenarios to predict future drought conditions. Our CNN model forecasts CDM values up to 2100, enabling accurate drought zoning. The results reveal significant trends in temperature changes, indicating areas most vulnerable to future droughts, while precipitation shows a slow increasing trend. Our analysis indicates that under extreme climate scenarios, certain regions may experience a significant increase in the frequency and severity of droughts, necessitating proactive planning and mitigation strategies. These findings are critical for policymakers and stakeholders in designing effective drought management and adaptation programs. [ABSTRACT FROM AUTHOR]

During the large-scale vegetation restoration on the Loess Plateau, the introduction of exotic species with high water consumption, such as Robinia pseudoacacia L., led to widespread soil desiccation, and resulted in severe drought stress and increasing risk of forest degradation and mortality. Accurate assessment of drought-induced mortality risk in plantation forests is essential for evaluating and enhancing the sustainability of ecological restoration, yet quantitative research at the regional scale on the Loess Plateau is lacking. With a focus on Robinia pseudoacacia L. plantations, we utilized a coupled model of the Biome BioGeochemical Cycles model and plant supply–demand hydraulic model (BBGC-SPERRY model) to simulate the dynamics of the annual average percentage loss of whole-plant hydraulic conductance (APLK) at 124 meteorological stations over an extended period (1961–2020) to examine changes in plant hydraulic safety in Robinia pseudoacacia L. plantations. Based on the probability distribution of APLK at each site, the drought-induced mortality risk probability (DMRP) in Robinia pseudoacacia L. was determined. The results indicate the BBGC-SPERRY model could effectively simulate the spatiotemporal variations in transpiration and evapotranspiration in Robinia pseudoacacia L. stands on the Loess Plateau. The mean APLK and DMRP exhibited increasing trends from southeast to northwest along a precipitation gradient, with their spatial patterns on the Loess Plateau mainly driven by mean annual precipitation and also significantly influenced by other climatic and soil factors. The low-risk (DMRP < 2%), moderate-risk (2% ≤ DMRP ≤ 5%), and high-risk (DMRP > 5%) zones for drought-induced mortality in Robinia pseudoacacia L. accounted for 60.0%, 30.7%, and 9.3% of the study area, respectively. These quantitative findings can provide an important basis for rational forestation and sustainable vegetation management on the Loess Plateau. [ABSTRACT FROM AUTHOR]