Drought Research Articles

Role of Novel Chlorella vulgaris SSAU8 in Improving the Soil Health Under Induced Drought Stress.

The severe climate change has caused a drastic water level disparity around the globe, which eventually has been one of the biggest problems of this era related to land degradation. This has caused the multidimensional impact on ecology, the environment, and their components. Algae, one of the ancient micro-engineers, are involved in the functioning of soil microcosm. Therefore, this study has utilized a novel alga, Chlorella vulgarisSSAU8 to observe the impact of low water potential induced by PEG-6000 (polyethylene glycol). The study has utilized the UV-Vis spectrophotometer to explore the nature of cyanobacteria by examining biomass and pigment concentrations. The assessment also includes the photosystem response, which was recorded by the Dual-modulation kinetic fluorometer FL3500/F (PSI, Brno, Czech Republic, version 3.7.0.1). The effect of PEG-6000-induced drought was seen to inhibit growth and biomass synthesis at > 30gL-1 concentration. It was also observed that the microbe could easily shuffle its photosystem behavior to nullify the effect of high PEG-6000 concentration, which shows the potential of the microbe in the water-deficient area and can be an important aspect to enhance soil fertility. Non-photochemical quenching and heat dissipation play a crucial role in cyanobacteria tolerating drought conditions. So, overall, this study thoroughly explores the behavior of Chlorella vulgarisSSAU8 in artificial drought stress and paves a way to combat one of the major environmental issues of the current era.

Effects of exogenous spraying of melatonin on the growth of Platycrater arguta under drought stress

Platycrater arguta is a rare and endangered deciduous shrub originating from the Tertiary Period. Understanding its drought tolerance is crucial for conservation efforts and enhancing its resilience to environmental stress. This study aimed to assess the effects of varying levels of drought stress on the phenotype and physiological–biochemical characteristics of P. arguta. The study subjected P. arguta to different levels of drought stress using 10%, 20%, and 30% polyethylene glycol-6000 (PEG-6000) over a 10-day period. Additionally, the effects of exogenous melatonin application at various concentrations (including 100 µM) were examined to determine its potential in alleviating drought-induced damage. Key parameters measured included leaf relative water content, net photosynthetic rate (Pn), antioxidant enzyme activity, and soluble sugar content. Drought stress significantly inhibited the growth of P. arguta. As PEG-6000 concentration increased, leaf relative water content and net photosynthetic rate decreased, while leaf wilting severity, membrane damage, antioxidant enzyme activity, and soluble sugar content increased. A 30% PEG-6000 concentration caused irreversible damage, leading to plant death. Exogenous application of 100 µM melatonin alleviated this damage by increasing leaf relative water content, enhancing photosynthetic efficiency, boosting antioxidant enzyme activity, accumulating osmotic regulators, and reducing leaf desiccation. The study demonstrated that P. arguta is sensitive to severe drought conditions, with 30% PEG-6000 causing irreversible damage. However, the application of 100 µM melatonin significantly improved the plant's drought tolerance by upregulating the expression of ABI1 and downregulating genes such as AUX1A-2, IAA2-2, and HP2-1. This finding highlights the potential of melatonin as a protective agent against drought stress, providing valuable insights for the conservation and enhancement of P. arguta's resilience to environmental challenges.

Physiological and transcriptomic analysis of the effect of overexpression of the NTPIP2;4 gene on drought tolerance in tobacco

Aquaporins are widely present in the plant kingdom and play important roles in plant response to abiotic adversity stresses such as water and temperature extremes. In this study, we investigated the regulatory role of NTPIP2;4 on drought tolerance in tobacco at physiological and transcriptional levels. In this experiment, we constructed an NtPIP2;4 overexpression vector and genetically transformed tobacco variety 'K326' to investigate the mechanism of NtPIP2;4 gene in regulating drought tolerance in tobacco at physiological and transcriptomic levels. Physiological analyses showed that overexpression plants showed low wilting under drought conditions compared to wild-type (WT), and NtPIP2;4 overexpression tobacco plants showed enhanced superoxide dismutase (SOD) and catalase (CAT) activities, lower levels of superoxide anion (O2-), malondialdehyde (MDA), and hydrogen peroxide (H2O2) than the control, and significantly higher proline (Pro) content than the control. The leaves of NtPIP2;4 overexpressing plants and wild-type controls after drought were subjected to transcriptome sequencing, and RNA-seq analysis showed that a total of 1752 differentially expressed genes (DEGs) were obtained under drought conditions, with 1005 DEGs of up-regulated and 747 DEGs of down-regulated differentially expressed genes. The DEGs were enriched mainly in the plant MAPK signaling pathway, the plant hormone signal transduction pathway, amino sugar and nucleotide sugar metabolism, starch and sucrose metabolism and plant-pathogen interaction pathways. We also investigated the drought pathway of MAPK pathway and the auxin pathway mechanism of plant hormone signal transduction pathway, and found that the transcript levels of the genes of the relevant pathways changed, and hypothesized that NtPIP2;4 might regulate the drought resistance of plants through the expression of the relevant genes induced by auxin. This study demonstrates that overexpression of NtPIP2;4 gene can enhance the drought resistance of tobacco plants, which will provide a basis for the research on the function of tobacco NtPIP2;4 gene and the creation of new germplasm resources.

Silica-Activated Redox Signaling Confers Rice with Enhanced Drought Resilience and Grain Yield.

Under a changing climate, enhancing the drought resilience of crops is critical to maintaining agricultural production and reducing food insecurity. Here, we demonstrate that seed priming with amorphous silica (SiO2) nanoparticles (NPs) (20 mg/L) accelerated seed germination speed, increased seedlings vigor, and promoted seedling growth of rice under polyethylene glycol (PEG)-mimicking drought conditions. An orthogonal approach was used to uncover the mechanisms of accelerated seed germination and enhanced drought tolerance, including electron paramagnetic resonance, Fourier transform infrared spectroscopy (FTIR), metabolomics, and transcriptomics. It was revealed that the unique surface chemistry of amorphous silica, characterized by an enrichment of silanol and siloxane groups, can catalyze the production of reactive oxygen species. This, in turn, initiates redox signaling and activates downstream drought-responsive genes. In addition, silica-primed seeds exhibited a significant enrichment of 18 amino acids and 6 sugars compared to those undergoing hydropriming, suggesting the accelerated mobilization of stored energy reserves. The drought-tolerance trait was observed in vegetative tissues of 35 day-old plants, where this tolerance was associated with an accelerated catabolism of amino acids and an enhanced anabolism of antioxidants. A separated field trial showed that SiO2NPs seed priming not only increased rice grain yield by 7.77% (p = 0.051) and 6.48% (p = 0.066), respectively, under normal and drought conditions but also increased the grain amino acid content. These results demonstrate that a simple and cost-effective nanoseed-priming approach can convey life cycle-long drought tolerance while simultaneously increasing rice grain yield and nutrition quality, providing an effective and sustainable strategy to cultivate climate-resilient crops.

Dual controls of vapour pressure deficit and soil moisture on photosynthesis in a restored temperate bog.

Despite only covering ~3% of the land mass, peatlands store more carbon (C) per unit area than any other ecosystem. This is due to the discrepancy between C fixed by the plants (Gross primary productivity (GPP)) and decomposition. However, this C is vulnerable to frequent, severe droughts and changes in the peatland microclimate. Plants play a vital role in ecosystem C dynamics under drought by mediating water loss to the atmosphere (surface water vapour conductance) and GPP by the presence/absence of stomatal regulation. This is dependent on soil moisture, air temperature, and vapour pressure deficit (VPD). Although there is ample evidence of the role of VPD on stomatal regulation and GPP, the impact of soil moisture is still debated. We addressed this knowledge gap by investigating the role of bulk surface conductance of water vapour in shifts between climatic (Air temperature (Tair), incoming shortwave radiation (SWR) and VPD) and water limitation of GPP in a peat bog in Canada. A causal analysis process was used to investigate how environmental factors influenced GPP. The results suggested that stomatal regulation in response to increased VPD caused the reduction in GPP in 2016 (~2.5gCm-2day-1 as opposed to ~3gCm-2day-1 in 2018). In contrast, GPP was limited again in 2019 due to the dry surface. This was driven by the relaxed stomatal regulation adopted by the ecosystem following the initial drought to maximise C assimilation. We found the threshold at which surface water decline limited GPP was at about -8cm water table depth (82.5% soil moisture). The causal inference corroborated our findings. The temporal variations of water and energy limitation seen in this study could increasingly restrict GPP due to the projected climate warming.

Influence of drought stress on phosphorus dynamics and maize growth in tropical ecosystems

Drought has a significant impact on ecosystem functions, especially on the biogeochemical cycling of phosphorus (P), which is a crucial nutrient for plant growth and productivity. Despite its importance, the effects of different drought scenarios on soil P cycling and availability remain poorly understood in previous studies. This study simulated drought conditions in tropical soils using maize as a test crop under varying field capacity (FC) levels (100%, 80%, 60%, 40%, and 20%) over a 60-day pot experiment. P uptake and plant biomass decreased significantly lower FC level. P uptake was highest at FC100 (5 g kg−¹) and lowest at FC20 (3.5 g kg−¹). Similarly, biomass was greatest at FC100 (70 g plant−¹) and declined to 35 g plant−¹ at FC20, underscoring the adverse effects of drought on P availability and growth. The results showed a substantial increase in calcium-associated P (HClD-Pi), reaching 45% at FC20. Conversely, labile inorganic P fractions (NaHCO₃-Pi and NaOH-Pi) decreased significantly, from 14.73 to 6.2 mg kg−¹ and 29.4 to 17.7 mg kg−¹, respectively, in FC20 compared to FC100. Organic P fractions (NaHCO₃-Po, NaOH-Po) increased by 6 and 2.4 times, respectively, under lower FC treatments, while HClc-Po was also elevated under drier conditions. These transformations were attributed to changes in soil pH and calcium content, favoring the stabilization of P as HClD-Pi. Drought disrupted the replenishment of inorganic P in the soil solution, reducing bioavailability, though phosphatase activity enhanced organic P release. Pearson’s correlation analysis revealed positive associations between labile and moderately labile P fractions (NaHCO₃-Pi, NaOH-Pi, HClD-Pi) and soil elements (Ca, Al, Fe). RDA highlighted a positive link between phosphatase activity and reduced labile P, while P uptake and biomass were strongly associated with labile and moderately labile P fractions. These findings demonstrate drought’s significant impact on P bioavailability, soil P cycling, and nutrient dynamics.

Axolotls, environmentally conscious mayors and watermills: Didactic proposals for raising awareness on water conservation through pedagogical translation

The present article explores the possibilities of integrating Sustainable Development Goal (SDG) #6 (Clean water and sanitation) in the content of materials designed for Spanish as a second or foreign language (S2/FL) learners in a Mexican context. The idea arose from the recent severe droughts in the country that affected water consumption in certain cities. For immersion students studying S2/FL in Mexico, this became a reality rarely discussed in the classroom. In addition, the use of pedagogical translation is proposed to take advantage of the opportunities offered by the learners’ already existing linguistics skills. Considering the particularities of the context where the project was developed, the material design stage was preceded by two smaller enquiries into the perception of Mexico and Mexican culture abroad as well as the country’s representation in existing S2/FL materials. One specific point of interest was if everyday realities where the lack of water received mention in the foreign press and / or if S2/FL textbooks. The resulting activities propose to cover these rather complex topics through a ludic perspective that can be replicated and adapted to a variety of contexts and any one of the SDG.

Long-term hydrological drought monitoring and trend analysis in Blue Nile River basin.

This research aims to monitor the hydrological drought trends within the geographical confines of Ethiopia, Sudan, and Egypt in the Blue Nile River Basin. Historical drought circumstances in the basin were analyzed through the utilization of the stream flow drought index (SDI). The long-term historical drought trend was investigated via the application of the Mann - Kendall Sen (MK) test. Streamflow data were collected at the border (GERD) (Ethiopia) and Khartoum and Dongola (Sudan) spanning the period from 1900 to 2001. Four distinct temporal scales were examined, including monthly (SDI1), seasonal (SDI3), bi-annual (SDI6), and annual (SDI12) frequency. Notably, SDI1, SDI3, and SDI6 exhibited a higher frequency of drought occurrences, whereas SDI12 demonstrated lower frequencies, accompanied by the longest duration of drought in all gauged stations. For the preceding 102-year period, two extreme drought events were identified across all stations: 1912/1913 and 1913/1914 in the Border and Dongola stations, and 1912/1913 and 1986/1987 in the Khartoum station. Moreover, the SDI12 results revealed that severe drought events manifested three, six, and four times, in the Border, Khartoum, and Dongola stations, respectively. Furthermore, an investigation of historical extreme and severe drought patterns led to the conclusion that extreme hydrological drought does not pose an imminent threat to downstream nations, including Egypt and Sudan. However, the trend analysis revealed that an increasing drought trend was observed in the Autumn season across all stations, while a positive trend characteristic of a wet condition was observed in the remaining seasons. Annual trend analysis did not show any statistically significant findings. Nevertheless, the study highlighted the imperative role of soil and water conservation measures in upstream countries, such as the Ethiopian highlands, in mitigating the prolonged effects of meteorological drought which gradually propagates into severe hydrological drought. Consequently, downstream nations must engage in cooperative efforts with upstream countries to address this issue collectively, rather than bestowing sole responsibility on the latter.

Analysis of the Propagation Characteristics of Meteorological Drought to Hydrological Drought and Their Joint Effects on Low-Flow Drought Variability in the Oum Er Rbia Watershed, Morocco

Analysis of the temporal relationship between meteorological drought and hydrological drought is crucial in monitoring water resource availability. This study examined the linear and lagged relationships of the spread of meteorological drought to hydrological drought and their joint effects on low-flow drought variability in the Oum Er-Rbia (OER) watershed. To this end, random forest (RF) model and statistical methods were used to study the characteristics of the temporal relationships between meteorological and hydrological drought indices at monthly, seasonal, and annual scales. The various analyses revealed that the relationship between hydrological and meteorological drought is mainly a function of the time scale considered, the choice of indices to describe each type of drought and the season considered. The hydrological drought of surface water and snow cover is synchronized with the meteorological drought at the monthly, seasonal, and annual scales. In contrast, the transition from meteorological drought to groundwater drought has a lag time of 1 month and is statistically significant up to t − 5 and t + 5, i.e., 6 months. The linear correlation between the annual rainfall deficit and the monthly groundwater storage index was the lowest (0.15) in December and the highest (0.83) in March. This suggests a seasonal response of groundwater drought to the cumulative effects of precipitation deficits. The RF analysis highlighted the importance of the cumulative characteristics of meteorological drought regarding the severity of low-flow drought. The meteorological drought indices at longer time scales have a greater impact on the severity of low-flow drought, with a contribution of approximately 10% per index. However, the relative contributions of meteorological factors and hydrological indices rarely exceed 5%. Thus, by exploring for the first time the complex interactions among the severity of low-flow regimes, meteorological and hydrological drought indices and meteorological factors, this study provides a new perspective for understanding the characteristics of propagation from meteorological to severe hydrological drought.

The Role of Organic Extracts and Inorganic Compounds as Alleviators of Drought Stress in Plants

Climate changes have exacerbated the progression of drought conditions on a global scalethreating to crop production and heightening concerns over food security. Water scarcity enforces alterations in fundamental morphology, physiology and biochemical traits in crops. Consequently, it is imperative to identify environmentally sustainable alternative solutions to mitigate this problem and enhance overall plant performance. In this sense, biostimulants have emerged as a promising alternative as they improve plant resilience, enhance physiological processes, and mitigate the detrimental consequences of water deficit conditions on crop production. This review compiles the latest research on the application of organic extracts and inorganic compounds in crops subjected to drought conditions, specifically humic acids, protein hydrolysates, seaweed extracts, and silicon. Moreover, it offers a comprehensive overview of the origins and effectiveness of these biostimulants, with a detailed analysis of their application and the associated physiological, biochemical, and genetic modifications induced by these bioactive compounds. This knowledge enhances the understanding of the efficacy and implementation strategies pertinent of these compounds under water stress scenarios in agricultural settings.

Effect of Drought Stress on Morphology and Chlorophyll Content of Sorghum (Sorghum bicolor L. Moench)

Sorghum is a type of cereal plant that easily adapts to stressful environmental conditions. Sorghum has many benefits as it can be used as food, feed, and energy sources, making it a promising crop for development on dry land in Indonesia. Drought impacts plants during their growth process, causing physiological and biological changes. This study aims to determine the effect of drought stress on the morphology and chlorophyll content of sorghum plants. Preliminary research was conducted by planting three varieties of sorghum (Numbu, Super 1, and Super 2). Subsequent planting involved selecting the variety most resistant to drought based on data analysis of several parameters. The basic design used in this experiment was a completely randomized design (CRD) with one factor: the level of drought stress, which had four levels -no drought stress as a day 0 (control) and drought stress for 3, 6 and 9 days by withholding water. The results showed a decrease in the total chlorophyll content of the leaves over time. Drought stress for 6 and 9 days without watering resulted in water content dropping below 25%, indicating severe drought stress and disrupting plant growth. Severe drought stress was characterized by low soil and leaf water content, yellowing and curling of the leaves.

Identifying Key Nodes and Enhancing Resilience in Grain Supply Chains Under Drought Conditions

Grain supply chains remain stable in the face of natural disasters, and the resilience of the grain supply chain plays an important role. In a complex scenario of exposure to shocks, it is significant to identify the critical nodes of the grain supply chain and propose countermeasures accordingly to enhance the resilience of the grain supply chain. In this paper’s study, firstly, a triangular model of contradictory events is used to describe complex scenarios and obtain Bayesian network nodes. Secondly, the fragmentation of the scenario is based on the description of the scene, the scene stream is constructed, the event network is obtained, and the Bayesian network structure is built on the basis. Then, combining expert knowledge and D–S evidence theory, the Bayesian network parameters are determined, and the Bayesian network model is built. Finally, the key nodes of the grain supply chain are identified in the context of the 2022 drought data in the Yangtze River Basin in China, and, accordingly, a strategy for improving the resilience of the grain supply chain is proposed in stages. This study provides a new research perspective on issues related to grain supply-chain resilience and enriches the theoretical foundation of research related to supply-chain resilience.

Recent Advances of Carbon Dots: Synthesis, Plants Applications, Prospects, and Challenges.

Nanomaterials and nanotechnology have garnered significant attention in the realm of agricultural production. Carbon dots (CDs), as a class of nanomaterials, play a crucial role in the field of plant growth due to their excellent properties. This review aims to summarize recent achievements on CDs, focusing on their methods of preparation and applications in plants systems. The effects of CDs on seed germination, growth, photosynthesis, nutritional quality, and stress resistance were studied. It has been demonstrated that CDs can promote seed germination and growth, as well as improve photosynthetic efficiency, ultimately leading to increase plants yield. The nutritional quality of the plants treated with CDs was significantly improved. Specifically, the levels of essential mineral elements, vitamins, amino acids, and other constituents that are beneficial to human health increased notably. Additionally, CDs show positive effects on augmenting plant resistance against environmental stresses, such as drought conditions, heavy metal toxicity, and high salinity. Finally, the prospects and challenges of the application of CDs in plant systems are also discussed, which provide a scientific basis for the future application of CDs in agricultural production.

Response mechanism of water status and photosynthetic characteristics of Cotoneaster multiflorus under drought stress and rehydrated conditions

IntroductionPlant physiology response and adaptation to drought stress has become a hotspot in plant ecology and evolution. Cotoneaster multiflorus possesses high ecological, ornamental and economic benefits. It has large root system and tolerance to cold, drought and poor soil. Therefore, C. multiflorus is considered as one of the most important tree species for ecological restoration in arid and semi-arid areas. However, little is known about the physiological mechanisms, molecular mechanisms and drought strategies of how C. multiflorus responds to drought stress. Therefore, exploring the physiological response mechanisms, molecular mechanisms and adaptive strategies of C. multiflorus in response to drought is important for its growth in arid and semi-arid regions.MethodsWe investigated the response and coupling mechanisms of water status, photosynthetic properties and chloroplast fluorescence parameters in C. multiflorus in response to drought and rehydrated after drought, especially the importance of nocturnal sap flow and nocturnal water refilling to maintain its own water balance in response to drought stress. In addition, we studied the stress response of C. multiflorus transcriptome factors, and we also discussed drought adaptation strategies of C. multiflorus.ResultsC. multiflorus adapted to drought stress by a series of structural and physiological mechanisms, such as promoting closing stomata, increasing nocturnal sap flow. When rehydrated after undergoing severe drought stress, its physiological activities such as photosynthesis, water status, chlorophyll fluorescence parameters and other physiological activities have rapidly resumed. This showed C. multiflorus had strong tolerance to drought. In addition, water status, photosynthetic characteristics, and chloroplast fluorescence parameters of C. multiflorus were highly coupled. Nocturnal sap flow and nocturnal water refilling were very important for C. multiflorus to maintain its own water balance in response to drought stress. Finally, C. multiflorus will strengthen the drought defense mechanism by gene regulation of various metabolisms, such as promoting stomatal closure, reducing transpiration water loss, and vigorously regulating water balance. C. multiflorus responded to drought stress by avoiding or reducing water deficit in plant organs and tissues. Therefore, the shrub C. multiflorus is a drought-tolerant plant.DiscussionWe explored the response mechanisms of water status, photosynthetic characteristics, and chloroplast fluorescence parameters of C. multiflorus in drought and rehydrated after drought stress, especially the response mechanisms of nocturnal sap flow and nocturnal water refilling in response to drought stress, and identified the physiological coupling mechanisms, molecular mechanisms and drought types of C. multiflorus in response to drought.

Green synthesized FeNPs ameliorate drought stress in Spinacia oleracea L. through improved photosynthetic capacity, redox balance, and antioxidant defense

The present study was designed to highlight the ameliorative role of iron nanoparticles (FeNPs) against drought stress in spinach (Spinacia oleracea L.) plants. A pot experiment was performed in two-way completely randomize design with three replicates. For drought stress three levels were used by maintaining field capacity of the soil. This included control (100% field capacity), moderate drought stress (D1; 50% field capacity) and severe drought stress (D2; 25% field capacity). FeNPs synthesized by green method using rice straw were applied along with precursor FeCl3, used as Fe source for the synthesis of FeNPs, through foliar spray (40 mg L− 1 for both). Growth parameters, efficiency of photosynthetic machinery, gas exchange attributes, total soluble proteins, and inorganic ions (Ca2+, K+ & Fe2+) were significantly reduced at both D1 and D2 stress levels, compared to control plants. Fe supplements in the form of FeCl3 and FeNPs improved these attributes in both control and drought conditions. Malondialdehyde, H2O2, relative membrane permeability (stress indicators) and the activities of antioxidants were increased in response to drought stress. Fe supplements further improved the antioxidant defense activities and efficiently lowered the effects of stress indicators. These effects of FeCl3 and FeNPs resulted in improved growth of S. oleracea plants in control and drought conditions. Results showed that FeNPs had more prominent effects on growth of S. oleracea plants compared to FeCl3. These findings suggest that FeNPs could be a helpful tool for lessening the harmful consequences of drought stress and this can be used for abiotic stress alleviation in other crops as well.

High‐throughput phenotyping of stay‐green in a sorghum breeding program using unmanned aerial vehicles and machine learning

AbstractAs climate change continues to influence global weather patterns, the frequency and severity of drought conditions are expected to increase, posing a significant challenge to crop production. In sorghum (Sorghum bicolor L. Moench), a key cereal crop, the stay‐green trait is of particular importance as a measure of how well a genotype can tolerate post‐anthesis drought conditions, which are critical for harvestable yield. Despite its importance, there is a pressing need for a more efficient, accurate, and precise method to phenotype stay‐green in sorghum to enhance breeding efforts. To address this need, this study explores the application of random forest and XGBoost machine learning models for phenotyping the stay‐green trait in sorghum. These models provide quantitative measurements that have the potential to enhance genomic studies and offer additional benefits. Although correlations with vegetation indices were occasionally high, they were not sufficiently reliable to be used exclusively. The machine learning models, in contrast, showed high percentages of genetic variation explained and had high repeatability. The values generated by these algorithms enable plant breeders to efficiently make selections in their stay‐green breeding programs. Further research is needed to assess the robustness of these models across different environments and genetic material. Additionally, comparing these models with other machine learning approaches will help determine if decision tree‐based models are the most effective for this application. Overall, the models presented in this study serve as a promising foundation for improving the efficiency of stay‐green breeding programs in sorghum, but they require further validation and comparison with alternative approaches.

Analysis of future climate variability under CMIP6 scenarios based on a downscaling method considering wet days in the upper Yangtze River basin, China

Abstract According to recent studies, the past decade was the hottest on record, and climate change is accelerating. As part of the Yangtze River Basin, the largest river basin in China, the Upper Yangtze River Basin (UYRB) plays a crucial role as the primary source of hydropower. However, the UYRB is also one of the most climate-sensitive regions within the basin, making the impact of climate change on this area particularly critical. We downscaled CMIP6 GCMs’ outputs of precipitation (including wet/dry spells sequence correction), and temperature projections (2024–2100), under four typical Shared Socioeconomic Pathways (SSPs), and we pursued a trend analysis upon these potential future climate series. We found significant upward trends in temperature across all SSPs in August, but no significant trends in precipitation for the same month. Additionally, for SSP370 and SSP585, there are significant upward trends in temperature in December, while precipitation showed no significant trends during that month. This may result in drier winters than now, increased potential evapotranspiration, and reduced surface (snow) water storage, impacting water resources availability. Consecutive dry/wet days at station, and basin scale show spatial-temporal heterogeneity, but generally wet spells are longer, and dry spells shorten moving from South-East to North-West.

Long-term climate establishes functional legacies by altering microbial traits.

Long-term climate history can influence rates of soil carbon cycling but the microbial traits underlying these legacy effects are not well understood. Legacies may result if historical climate differences alter the traits of soil microbial communities, particularly those associated with carbon cycling and stress tolerance. However, it is also possible that contemporary conditions can overcome the influence of historical climate, particularly under extreme conditions. Using shotgun metagenomics, we assessed the composition of soil microbial functional genes across a mean annual precipitation gradient that previously showed evidence of strong climate legacies in soil carbon flux and extracellular enzyme activity. Sampling coincided with recovery from a regional, multi-year severe drought, allowing us to document how the strength of climate legacies varied with contemporary conditions. We found increased investment in genes associated with resource cycling with historically higher precipitation across the gradient, particularly in traits related to resource transport and complex carbon degradation. This legacy effect was strongest in seasons with the lowest soil moisture, suggesting that contemporary conditions-particularly, resource stress under water limitation-influences the strength of legacy effects. In contrast, investment in stress tolerance did not vary with historical precipitation, likely due to frequent periodic drought throughout the gradient. Differences in the relative abundance of functional genes explained over half of variation in microbial functional capacity-potential enzyme activity-more so than historical precipitation or current moisture conditions. Together, these results suggest that long-term climate can alter the functional potential of soil microbial communities, leading to legacies in carbon cycling.

Data-Driven Decision Support to Guide Sustainable Grazing Management

Data-driven decision support can help guide sustainable grazing management by providing an accurate estimate of grazing capacity, in coproduction with managers. Here, we described the development of a decision support model to estimate grazing capacity and illustrated its application on two sites in the western United States. For the Montgomery Pass Wild Horse Territory in California and Nevada, the upper limit estimated in the capacity assessment was 398 horses and the current population was 654 horses. For the Eagle Creek watershed of the Apache–Sitgreaves National Forest of eastern Arizona, the lower end of capacity was estimated at 1560 cattle annually, compared to the current average of 1090 cattle annually. In addition to being spatio-temporally comprehensive, the model provides a repeatable, cost-effective, and transparent process for establishing and adjusting capacity estimates and associated grazing plans that are supported by scientific information, in order to support livestock numbers at levels that are sustainable over time, including levels that are below average forage production during drought conditions. This modeling process acts as a decision support tool because it enables different assumptions to be used and explored to accommodate multiple viewpoints during the planning process.

Spatiotemporal Dynamics of Drought in the Huai River Basin (2012–2018): Analyzing Patterns Through Hydrological Simulation and Geospatial Methods

As climate change intensifies, extreme drought events have become more frequent, and investigating the mechanisms of watershed drought has become highly significant for basin water resource management. This study utilizes the WRF-Hydro model in conjunction with standardized drought indices, including the standardized precipitation index (SPI), standardized soil moisture index (SSMI), and Standardized Streamflow Index (SSFI), to comprehensively investigate the spatiotemporal characteristics of drought in the Huai River Basin, China, from 2012 to 2018. The simulation performance of the WRF-Hydro model was evaluated by comparing model outputs with reanalysis data at the regional scale and site observational data at the site scale, respectively. Our results demonstrate that the model showed a correlation coefficient of 0.74, a bias of −0.29, and a root mean square error of 2.66% when compared with reanalysis data in the 0–10 cm soil layer. Against the six observational sites, the model achieved a maximum correlation coefficient of 0.81, a minimum bias of −0.54, and a minimum root mean square error of 3.12%. The simulation results at both regional and site scales demonstrate that the model achieves high accuracy in simulating soil moisture in this basin. The analysis of SPI, SSMI, and SSFI from 2012 to 2018 shows that the summer months rarely experience drought, and droughts predominantly occurred in December, January, and February in the Huai River Basin. Moreover, we found that the drought characteristics in this basin have significant seasonal and interannual variability and spatial heterogeneity. On the one hand, the middle and southern parts of the basin experience more frequent and severe agricultural droughts compared to the northern regions. On the other hand, we identified a time–lag relationship among meteorological, agricultural, and hydrological droughts, uncovering interactions and propagation mechanisms across different drought types in this basin. Finally, we concluded that the WRF-Hydro model can provide highly accurate soil moisture simulation results and can be used to assess the spatiotemporal variations in regional drought events and the propagation mechanisms between different types of droughts.